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  • 51.
    Bai, Sai
    et al.
    Zhejiang University, Peoples R China.
    He, Shasha
    Zhejiang University, Peoples R China.
    Jin, Yizheng
    Zhejiang University, Peoples R China.
    Wu, Zhongwei
    Soochow University, Peoples R China.
    Xia, Zhouhui
    Soochow University, Peoples R China.
    Sun, Baoquan
    Soochow University, Peoples R China.
    Wang, Xin
    Zhejiang University, Peoples R China.
    Ye, Zhizhen
    Zhejiang University, Peoples R China.
    Gao, Feng
    Linköping University, Department of Physics, Chemistry and Biology, Biomolecular and Organic Electronics. Linköping University, The Institute of Technology.
    Shao, Shuyan
    Zhang, Fengling
    Linköping University, Department of Physics, Chemistry and Biology, Biomolecular and Organic Electronics. Linköping University, The Institute of Technology.
    Electrophoretic deposited oxide thin films as charge transporting interlayers for solution-processed optoelectronic devices: the case of ZnO nanocrystals2015In: RSC Advances, ISSN 2046-2069, E-ISSN 2046-2069, Vol. 5, no 11, p. 8216-8222Article in journal (Refereed)
    Abstract [en]

    A promising fabrication method of electron transporting interlayers for solution-processed optoelectronic devices by electrophoretic deposition (EPD) of colloidal zinc oxide (ZnO) nanocrystals was demonstrated. A low voltage of 3-5 V and a short deposition time of 40 s at room temperature were found to be sufficient to generate dense and uniform ZnO thin films. The EPD ZnO nanocrystal films were applied as ETLs for inverted organic solar cell and polymer light emitting diodes (PLEDs). By optimizing the EPD processing of ZnO nanocrystal electron transporting layers (ETLs), inverted organic solar cells based on [3,4-b]-thiophene/benzodithiophene (PTB7): [6-6]-phenyl-C71-butyric acid methyl ester (PC71BM) and poly(3-hexylthiophene) (P3HT): [6-6]-phenyl-C-61-butyric acid methyl ester (PC61BM) with an average PCE of 8.4% and 4.0% were fabricated. In combination with the PLEDs and flexible devices results, we conclude that the EPD processed ZnOnanocrystal thin films can serve as high quality ETLs for solution-processed optoelectronic devices.

  • 52.
    Bai, Sai
    et al.
    Zhejiang University, Peoples R China; Zhejiang University, Peoples R China.
    Jin, Yizheng
    Zhejiang University, Peoples R China; Zhejiang University, Peoples R China.
    Liang, Xiaoyong
    Zhejiang University, Peoples R China; Zhejiang University, Peoples R China.
    Ye, Zhizhen
    Zhejiang University, Peoples R China; Zhejiang University, Peoples R China.
    Wu, Zhongwei
    Soochow University, Peoples R China.
    Sun, Baoquan
    Soochow University, Peoples R China.
    Ma, Zaifei
    Linköping University, Department of Physics, Chemistry and Biology, Biomolecular and Organic Electronics. Linköping University, The Institute of Technology.
    Tang, Zheng
    Linköping University, Department of Physics, Chemistry and Biology, Biomolecular and Organic Electronics. Linköping University, The Institute of Technology.
    Wang, Jianpu
    Nanjing Technical University, Peoples R China.
    Wuerfel, Uli
    Fraunhofer Institute Solar Energy Syst ISE, Germany; University of Freiburg, Germany.
    Gao, Feng
    Linköping University, Department of Physics, Chemistry and Biology, Biomolecular and Organic Electronics. Linköping University, The Institute of Technology.
    Zhang, Fengling
    Linköping University, Department of Physics, Chemistry and Biology, Biomolecular and Organic Electronics. Linköping University, The Institute of Technology.
    Ethanedithiol Treatment of Solution-Processed ZnO Thin Films: Controlling the Intragap States of Electron Transporting Interlayers for Efficient and Stable Inverted Organic Photovoltaics2015In: ADVANCED ENERGY MATERIALS, ISSN 1614-6832, Vol. 5, no 5, p. 1401606-Article in journal (Refereed)
    Abstract [en]

    The surface defects of solution-processed ZnO films lead to various intragap states. When the solution-processed ZnO films are used as electron transport interlayers (ETLs) in inverted organic solar cells, the intragap states act as interfacial recombination centers for photogenerated charges and thereby degrade the device performance. Here, a simple passivation method based on ethanedithiol (EDT) treatment is demonstrated, which effectively removes the surface defects of the ZnO nanocrystal films by forming zinc ethanedithiolates. The passivation by EDT treatment modulates the intragap states of the ZnO films and introduces a new intragap band. When the EDT-treated ZnO nanocrystal films are used as ETLs in inverted organic solar cells, both the power conversion efficiency and stability of the devices are improved. The control studies show that the solar cells with EDT-treated ZnO films exhibit reduced charge recombination rates and enhanced charge extraction properties. These features are consistent with the fact that the modulation of the intragap states results in reduction of interfacial recombination as well as the improved charge selectivity and electron transport properties of the ETLs. It is further demonstrated that the EDT treatment-based passivation method can be extended to ZnO films deposited from sol-gel precursors.

  • 53.
    Bai, Sai
    et al.
    Linköping University, Department of Physics, Chemistry and Biology, Biomolecular and Organic Electronics. Linköping University, Faculty of Science & Engineering. Univ Oxford, England.
    Sakai, Nobuya
    Univ Oxford, England.
    Zhang, Wei
    Univ Oxford, England; Univ Lincoln, England.
    Wang, Zhiping
    Univ Oxford, England.
    Wang, Jacob T.-W.
    Univ Oxford, England.
    Gao, Feng
    Linköping University, Department of Physics, Chemistry and Biology, Biomolecular and Organic Electronics. Linköping University, Faculty of Science & Engineering. Univ Oxford, England.
    Snaith, Henry J.
    Univ Oxford, England.
    Reproducible Planar Heterojunction Solar Cells Based on One-Step Solution-Processed Methylammonium Lead Halide Perovskites2017In: Chemistry of Materials, ISSN 0897-4756, E-ISSN 1520-5002, Vol. 29, no 1, p. 462-473Article in journal (Refereed)
    Abstract [en]

    Metal halide perovskites have been demonstrated as one of the most promising materials for low-cost and high-performance photovoltaic applications. However, due to the susceptible crystallization process of perovskite films on planar substrates and the high sensitivity of the physical and optoelectronic nature of the internal interfaces within the devices, researchers in different laboratories still experience poor reproducibility in fabricating efficient perovskite solar cells with planar heterojunction device structures. In this method paper, we present detailed information on the reagents, equipment, and procedures for the fabrication of planar perovskite solar cells in both "regular" n-i-p and "inverted" p-i-n architectures based on one-step solution-processed methylammonium lead triiodide (MAPbI(3)) perovskite films. We discuss key parameters affecting the crystallization of perovskite and the device interfaces. This method paper will provide a guideline for the reproducible fabrication of planar heterojunction solar cells based on MAPbI3 perovskite films. We believe that the shared experience on MA-based perovskite films and planar solar cells will be also useful for the optimization process of perovskites with varied compositions, and other emerging perovskite-based optoelectronic devices.

  • 54.
    Bai, Sai
    et al.
    Linköping University, Department of Physics, Chemistry and Biology, Biomolecular and Organic Electronics. Linköping University, Faculty of Science & Engineering.
    Yuan, Zhongcheng
    Linköping University, Department of Physics, Chemistry and Biology, Biomolecular and Organic Electronics. Linköping University, Faculty of Science & Engineering.
    Gao, Feng
    Linköping University, Department of Physics, Chemistry and Biology, Biomolecular and Organic Electronics. Linköping University, Faculty of Science & Engineering.
    Colloidal metal halide perovskite nanocrystals: synthesis, characterization, and applications2016In: Journal of Materials Chemistry C, ISSN 2050-7526, E-ISSN 2050-7534, Vol. 4, no 18, p. 3898-3904Article in journal (Refereed)
    Abstract [en]

    Colloidal metal halide perovskite nanocrystals (NCs) have emerged as promising materials for optoelectronic devices and received considerable attention recently. Their superior photoluminescence (PL) properties provide significant advantages for lighting and display applications. In this Highlight, we discuss recent developments in the design and chemical synthesis of colloidal perovskite NCs, including both organic-inorganic hybrid and all inorganic perovskite NCs. We review the excellent PL properties and current optoelectronic applications of these perovskite NCs. In addition, critical challenges that currently limit the applicability of perovskite NCs are discussed, and prospects for future directions are proposed.

  • 55.
    Bakulin, Artem A.
    et al.
    FOM Institute AMOLF, Netherlands; University of Cambridge, England.
    Xia, Yuxin
    Linköping University, Department of Physics, Chemistry and Biology, Biomolecular and Organic Electronics. Linköping University, Faculty of Science & Engineering.
    Bakker, Huib J.
    FOM Institute AMOLF, Netherlands.
    Inganäs, Olle
    Linköping University, Department of Physics, Chemistry and Biology, Biomolecular and Organic Electronics. Linköping University, Faculty of Science & Engineering.
    Gao, Feng
    Linköping University, Department of Physics, Chemistry and Biology, Biomolecular and Organic Electronics. Linköping University, Faculty of Science & Engineering.
    Morphology, Temperature, and Field Dependence Separation in High-Efficiency Solar Cells Based on Polyquinoxaline Copolymer2016In: The Journal of Physical Chemistry C, ISSN 1932-7447, E-ISSN 1932-7455, Vol. 120, no 8, p. 4219-4226Article in journal (Refereed)
    Abstract [en]

    Charge separation and recombination are key processes determining the performance of organic optoelectronic devices. Here we combine photoluminescence and photovoltaic characterization of organic solar cell devices with ultrafast multipulse photocurrent spectroscopy to investigate charge generation mechanisms in the organic photovoltaic devices based on a blend of an alternating polyquinoxaline copolymer with fullerene. The combined use of these techniques enables the determination of the contributions of geminate and bimolecular processes to the solar cell performance. We observe that charge separation is not a temperature-activated process in the studied materials. At the same time, the generation of free charges shows a dear external field and morphology dependence. This indicates that the critical step of charge separation involves the nonequilibrium state that is formed at early times after photoexcitation, when the polaronic localization is not yet complete. This work reveals new aspects of molecular level charge dynamics in the organic light-conversion systems.

  • 56.
    Bao, Chunxiong
    et al.
    Linköping University, Department of Physics, Chemistry and Biology, Biomolecular and Organic Electronics. Linköping University, Faculty of Science & Engineering. Shenzhen Univ, Peoples R China.
    Yang, Jie
    Linköping University, Department of Physics, Chemistry and Biology, Biomolecular and Organic Electronics. Linköping University, Faculty of Science & Engineering. Southeast Univ, Peoples R China.
    Bai, Sai
    Linköping University, Department of Physics, Chemistry and Biology, Biomolecular and Organic Electronics. Linköping University, Faculty of Science & Engineering.
    Xu, Weidong
    Linköping University, Department of Physics, Chemistry and Biology, Biomolecular and Organic Electronics. Linköping University, Faculty of Science & Engineering.
    Yan, Zhibo
    Linköping University, Department of Physics, Chemistry and Biology, Biomolecular and Organic Electronics. Linköping University, Faculty of Science & Engineering. Nanjing Univ, Peoples R China.
    Xu, Qingyu
    Southeast Univ, Peoples R China.
    Liu, Junming
    Nanjing Univ, Peoples R China.
    Zhang, Wenjing
    Shenzhen Univ, Peoples R China.
    Gao, Feng
    Linköping University, Department of Physics, Chemistry and Biology, Biomolecular and Organic Electronics. Linköping University, Faculty of Science & Engineering.
    High Performance and Stable All-Inorganic Metal Halide Perovskite-Based Photodetectors for Optical Communication Applications2018In: Advanced Materials, ISSN 0935-9648, E-ISSN 1521-4095, Vol. 30, no 38, article id 1803422Article in journal (Refereed)
    Abstract [en]

    Photodetectors are critical parts of an optical communication system for achieving efficient photoelectronic conversion of signals, and the response speed directly determines the bandwidth of the whole system. Metal halide perovskites, an emerging class of low-cost solution-processed semiconductors, exhibiting strong optical absorption, low trap states, and high carrier mobility, are widely investigated in photodetection applications. Herein, through optimizing the device engineering and film quality, high-performance photodetectors based on all-inorganic cesium lead halide perovskite (CsPbIxBr3-x), which simultaneously possess high sensitivity and fast response, are demonstrated. The optimized devices processed from CsPbIBr2 perovskite show a practically measured detectable limit of about 21.5 pW cm(-2) and a fast response time of 20 ns, which are both among the highest reported device performance of perovskite-based photodetectors. Moreover, the photodetectors exhibit outstanding long-term environmental stability, with negligible degradation of the photoresponse property after 2000 h under ambient conditions. In addition, the resulting perovskite photodetector is successfully integrated into an optical communication system and its applications as an optical signal receiver on transmitting text and audio signals is demonstrated. The results suggest that all-inorganic metal halide perovskite-based photodetectors have great application potential for optical communication.

  • 57.
    Bao, Qinye
    et al.
    Linköping University, Department of Physics, Chemistry and Biology, Surface Physics and Chemistry. Linköping University, Faculty of Science & Engineering.
    Fabiano, Simone
    Linköping University, Department of Science and Technology, Physics and Electronics. Linköping University, Faculty of Science & Engineering.
    Andersson, Mattias
    Linköping University, Department of Physics, Chemistry and Biology, Biomolecular and Organic Electronics. Linköping University, The Institute of Technology.
    Braun, Slawomir
    Linköping University, Department of Physics, Chemistry and Biology, Surface Physics and Chemistry. Linköping University, Faculty of Science & Engineering.
    Sun, Zhengyi
    Linköping University, Department of Physics, Chemistry and Biology, Surface Physics and Chemistry. Linköping University, The Institute of Technology.
    Crispin, Xavier
    Linköping University, Department of Science and Technology, Physics and Electronics. Linköping University, Faculty of Science & Engineering.
    Berggren, Magnus
    Linköping University, Department of Science and Technology, Physics and Electronics. Linköping University, Faculty of Science & Engineering.
    Liu, Xianjie
    Linköping University, Department of Physics, Chemistry and Biology, Surface Physics and Chemistry. Linköping University, Faculty of Science & Engineering.
    Fahlman, Mats
    Linköping University, Department of Physics, Chemistry and Biology, Surface Physics and Chemistry. Linköping University, Faculty of Science & Engineering.
    Energy Level Bending in Ultrathin Polymer Layers Obtained through Langmuir-Shafer Deposition2016In: Advanced Functional Materials, ISSN 1616-301X, E-ISSN 1616-3028, Vol. 26, no 7, p. 1077-1084Article in journal (Refereed)
    Abstract [en]

    The semiconductor-electrode interface impacts the function and the performance of (opto) electronic devices. For printed organic electronics the electrode surface is not atomically clean leading to weakly interacting interfaces. As a result, solution-processed organic ultrathin films on electrodes typically form islands due to dewetting. It has therefore been utterly difficult to achieve homogenous ultrathin conjugated polymer films. This has made the investigation of the correct energetics of the conjugated polymer-electrode interface impossible. Also, this has hampered the development of devices including ultrathin conjugated polymer layers. Here, LangmuirShafer-manufactured homogenous mono-and multilayers of semiconducting polymers on metal electrodes are reported and the energy level bending using photoelectron spectroscopy is tracked. The amorphous films display an abrupt energy level bending that does not extend beyond the first monolayer. These findings provide new insights of the energetics of the polymer-electrode interface and opens up for new high-performing devices based on ultrathin semiconducting polymers.

  • 58.
    Bao, Qinye
    et al.
    Linköping University, Department of Physics, Chemistry and Biology, Surface Physics and Chemistry. Linköping University, Faculty of Science & Engineering.
    Fabiano, Simone
    Linköping University, Department of Science and Technology, Physics and Electronics. Linköping University, Faculty of Science & Engineering.
    Andersson, Mattias
    Linköping University, Department of Physics, Chemistry and Biology, Biomolecular and Organic Electronics. Linköping University, Faculty of Science & Engineering.
    Braun, Slawomir
    Linköping University, Department of Physics, Chemistry and Biology, Surface Physics and Chemistry. Linköping University, Faculty of Science & Engineering.
    Sun, Zhengyi
    Linköping University, Department of Physics, Chemistry and Biology, Surface Physics and Chemistry. Linköping University, Faculty of Science & Engineering.
    Crispin, Xavier
    Linköping University, Department of Science and Technology, Physics and Electronics. Linköping University, Faculty of Science & Engineering.
    Berggren, Magnus
    Linköping University, Department of Science and Technology, Physics and Electronics. Linköping University, Faculty of Science & Engineering.
    Liu, Xianjie
    Linköping University, Department of Physics, Chemistry and Biology, Surface Physics and Chemistry. Linköping University, Faculty of Science & Engineering.
    Fahlman, Mats
    Linköping University, Department of Physics, Chemistry and Biology, Surface Physics and Chemistry. Linköping University, Faculty of Science & Engineering.
    The energetics of the semiconducting polymer-electrode interface for solution-processed electronicsManuscript (preprint) (Other academic)
    Abstract [en]

    The semiconductor-electrode interface impacts the function and the performance of (opto-)electronic devices. For printed organic electronics the electrode surface is not atomically clean leading to weakly interacting interfaces. As a result, solution-processed organic ultra-thin films on electrodes typically form islands due to de-wetting. It has therefore been utterly difficult to achieve homogenous ultrathin conjugated polymer films. This has made the investigation of the correct energetics of the conjugated polymer-electrode interface impossible. Also, this has hampered the development of devices including ultra-thin conjugated polymer layers. Here, we report Langmuir-Shäfer-manufactured homogenous mono- and multilayers of semiconducting polymers on metal electrodes and track the energy level bending using photoelectron spectroscopy. The amorphous films display an abrupt energy level bending that does not extend beyond the first monolayer. Our findings provide new insights of the energetics of the polymer-electrode interface and opens up for new high-performing devices based on ultra-thin semiconducting polymers.

  • 59.
    Bao, Qinye
    et al.
    Linköping University, Department of Physics, Chemistry and Biology, Surface Physics and Chemistry. Linköping University, The Institute of Technology.
    Liu, Xianjie
    Linköping University, Department of Physics, Chemistry and Biology, Surface Physics and Chemistry. Linköping University, The Institute of Technology.
    Braun, Slawomir
    Linköping University, Department of Physics, Chemistry and Biology, Surface Physics and Chemistry. Linköping University, The Institute of Technology.
    Gao, Feng
    Linköping University, Department of Physics, Chemistry and Biology, Biomolecular and Organic Electronics. Linköping University, The Institute of Technology.
    Fahlman, Mats
    Linköping University, Department of Physics, Chemistry and Biology, Surface Physics and Chemistry. Linköping University, The Institute of Technology.
    Energetics at Doped Conjugated Polymer/Electrode Interfaces2015In: ADVANCED MATERIALS INTERFACES, ISSN 2196-7350, Vol. 2, no 2Article in journal (Refereed)
    Abstract [en]

    n/a

  • 60.
    Bao, Qinye
    et al.
    Linköping University, Department of Physics, Chemistry and Biology, Surface Physics and Chemistry. Linköping University, Faculty of Science & Engineering.
    Liu, Xianjie
    Linköping University, Department of Physics, Chemistry and Biology, Surface Physics and Chemistry. Linköping University, Faculty of Science & Engineering.
    Wang, Ergang
    Department of Chemistry and Chemical Engineering, Chalmers University of Technology, Göteborg, Sweden.
    Fang, Junfeng
    Ningbo Institute of Material Technology and Engineering, Chinese Academy of Science, Ningbo, PR China.
    Gao, Feng
    Linköping University, Department of Physics, Chemistry and Biology, Biomolecular and Organic Electronics. Linköping University, Faculty of Science & Engineering. State Key Laboratory of Luminescent Materials and Devices, South China University of Technology, Guangzhou, P. R. China.
    Braun, Slawomirslama19
    Linköping University, Department of Physics, Chemistry and Biology, Surface Physics and Chemistry. Linköping University, Faculty of Science & Engineering.
    Fahlman, Mats
    Linköping University, Department of Physics, Chemistry and Biology, Surface Physics and Chemistry. Linköping University, Faculty of Science & Engineering.
    Regular Energetics at Conjugated Electrolyte/Electrode Modifier for Organic Electronics and Their Implications of Design Rules2015In: Advanced Materials Interfaces, ISSN 2196-7350, Vol. 2, no 12, p. 1-6, article id 1500204Article in journal (Refereed)
    Abstract [en]

    Regular energetics at a conjugated electrolyte/electrode modifier are found and controlled by equilibration of the Fermi level and an additional interface double dipole step induced by ionic functionality. Based on the results, design rules for conjugated electrolyte/electrode modifiers to achieve the smallest charge injection/exaction barrier and break through the current thickness limitation are proposed.

  • 61.
    Bao, Qinye
    et al.
    Linköping University, Department of Physics, Chemistry and Biology, Surface Physics and Chemistry. Linköping University, The Institute of Technology.
    Liu, Xianjie
    Linköping University, Department of Physics, Chemistry and Biology, Surface Physics and Chemistry. Linköping University, The Institute of Technology.
    Xia, Yuxin
    Linköping University, Department of Physics, Chemistry and Biology, Biomolecular and Organic Electronics. Linköping University, The Institute of Technology.
    Gao, Feng
    Linköping University, Department of Physics, Chemistry and Biology, Biomolecular and Organic Electronics. Linköping University, The Institute of Technology.
    Kauffmann, Louis-Dominique
    GenesInk, France.
    Margeat, Olivier
    Aix Marseille University, France.
    Ackermann, Jorg
    Aix Marseille University, France.
    Fahlman, Mats
    Linköping University, Department of Physics, Chemistry and Biology, Surface Physics and Chemistry. Linköping University, The Institute of Technology.
    Effects of ultraviolet soaking on surface electronic structures of solution processed ZnO nanoparticle films in polymer solar cells2014In: Journal of Materials Chemistry A, ISSN 2050-7488, Vol. 2, no 41, p. 17676-17682Article in journal (Refereed)
    Abstract [en]

    We systematically show the effect of UV-light soaking on surface electronic structures and chemical states of solution processed ZnO nanoparticle (ZnONP) films in UHV, dry air and UV-ozone. UV exposure in UHV induces a slight decrease in work function and surface-desorption of chemisorbed oxygen, whereas UV exposure in the presence of oxygen causes an increase in work function due to oxygen atom vacancy filling in the ZnO matrix. We demonstrate that UV-light soaking in combination with vacuum or oxygen can tune the work function of the ZnONP films over a range exceeding 1 eV. Based on photovoltaic performance and diode measurements, we conclude that the oxygen atom vacancy filling occurs mainly at the surface of the ZnONP films and that the films consequently retain their n-type behavior despite a significant increase in the measured work function.

  • 62.
    Barrau, Sophie
    et al.
    Linköping University, Department of Physics, Chemistry and Biology, Biomolecular and Organic Electronics. Linköping University, Faculty of Science & Engineering.
    Andersson, Viktor
    Linköping University, Department of Physics, Chemistry and Biology, Biomolecular and Organic Electronics. Linköping University, Faculty of Science & Engineering.
    Zhang, Fengling
    Linköping University, Department of Physics, Chemistry and Biology, Biomolecular and Organic Electronics. Linköping University, The Institute of Technology.
    Masich, Sergej
    Karolinska Institutet, Stockholm.
    Bijleveld, Johan
    Chalmers University of Technology, Göteborg.
    Andersson, Mats R
    Chalmers University of Technology, Göteborg.
    Inganäs, Olle
    Linköping University, Department of Physics, Chemistry and Biology, Biomolecular and Organic Electronics. Linköping University, The Institute of Technology.
    Nanomorphology of Bulk Heterojunction Organic Solar Cells in 2D and 3D Correlated to Photovoltaic Performance2009In: Macromolecules, ISSN 0024-9297, E-ISSN 1520-5835, Vol. 42, no 13, p. 4646-4650Article in journal (Refereed)
    Abstract [en]

    Control of the nanoscale morphology of the donor-acceptor material blends inorganic solar Cells is critical for optimizing the photovoltaic performances. The influence of intrinsic (acceptor materials) and extrinsic (donor:acceptor weight ratio, substrate, solvent) parameters was investigated, by atomic force microscopy (AFM) and electron tomography (ET), on the nanoscale phase separation of blends of a low-band-gap alternating polyfluorene copolymers (APFO-Green9) with [6,6]-phenyl-C-71-butyric acid methyl ester ([70]PCBM). The photovoltaic performances display an optimal efficiency for the device elaborated with a 1:3 APFO-Green polymer:[70][PCBM weight ratio and spin-coated from chloroform solution. The associated active layer morphology presents small phase-separated domains which is a good balance between as a large interfacial donor-acceptor area and Continuous paths of the donor and acceptor phases to the electrodes.

  • 63.
    Barrau, Sophie
    et al.
    Linköping University, The Institute of Technology. Linköping University, Department of Physics, Chemistry and Biology.
    Zhang, Fengling
    Linköping University, The Institute of Technology. Linköping University, Department of Physics, Chemistry and Biology, Biomolecular and Organic Electronics .
    Herland, Anna
    Linköping University, The Institute of Technology. Linköping University, Department of Physics, Chemistry and Biology, Biomolecular and Organic Electronics .
    Mammo, W.
    Chalmers University of Technology.
    Andersson, Mats R.
    Chalmers University of Technology.
    Inganäs, Olle
    Linköping University, The Institute of Technology. Linköping University, Department of Physics, Chemistry and Biology, Biomolecular and Organic Electronics .
    Integration of Amyloid Nanowires in Organic Solar Cells2008In: Applied Physics Letters, ISSN 0003-6951, E-ISSN 1077-3118, Vol. 93, p. 23307-Article in journal (Refereed)
    Abstract [en]

      

  • 64.
    Belgardt, Christian
    et al.
    Chemnitz University of Technology, Center for Nanostructured Materials and Analytics (nanoMA), Germany.
    Sowade, Enrico
    Chemnitz University of Technology, Digital Printing and Imaging, Germany .
    Blaudeck, Thomas
    Linköping University, Department of Physics, Chemistry and Biology, Biomolecular and Organic Electronics. Linköping University, The Institute of Technology.
    Baumgärtel, Thomas
    Chemnitz University of Technology, Center for Nanostructured Materials and Analytics (nanoMA), Germany.
    Graaf, Harald
    Chemnitz University of Technology, Center for Nanostructured Materials and Analytics (nanoMA), Germany.
    von Borczyskowski, Christian
    Chemnitz University of Technology, Center for Nanostructured Materials and Analytics (nanoMA), Germany.
    Baumann, Reinhard R
    Chemnitz University of Technology, Digital Printing and Imaging, Germany .
    Inkjet printing as a tool for the patterned deposition of octadecylsiloxane monolayers on silicon oxide surfaces2013In: Physical Chemistry, Chemical Physics - PCCP, ISSN 1463-9076, E-ISSN 1463-9084, Vol. 15, no 20, p. 7494-504Article in journal (Refereed)
    Abstract [en]

    We present a case study about inkjet printing as a tool for molecular patterning of silicon oxide surfaces with hydrophobic functionality, mediated by n-octadecyltrichlorosilane (OTS) molecules. In contrast to state-of-the-art techniques such as micro contact printing or chemical immersion with subsequent lithography processes, piezo drop-on-demand inkjet printing does not depend on physical masters, which allows an effective direct-write patterning of rigid or flexible substrates and enables short run-lengths of the individual pattern. In this paper, we used mesithylene-based OTS inks, jetted them in droplets of 10 pL on a silicon oxide surface, evaluated the water contact angle of the patterned areas and fitted the results with Cassie's law. For inks of 2.0 mM OTS concentration, we found that effective area coverages of 38% can be obtained. Our results hence show that contact times of the order of hundred milliseconds are sufficient to form a pattern of regions with OTS molecules adsorbed to the surface, representing at least a fragmented, inhomogeneous self-assembled OTS monolayer (OTS-SAM).

  • 65.
    Bergqvist, Jonas
    Linköping University, Department of Physics, Chemistry and Biology, Biomolecular and Organic Electronics .
    Microstructure and Temperature Stability of APFO-3:PCBM Organic Photovoltaic Blends2010Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    In this thesis, the microstructure of organic photovoltaic APFO-3:PC61BM bulk-heterojunction blends was examined. Earlier studies have focused on the microstructure after spin coating. This thesis aims to give a better insight into microstructural degradation as the films are annealed above the glass transition temperature, Tg, and the mixture approaches thermodynamic equilibrium. Electro- and photoluminescence studies indicate that the polymer and PC61BM are intermixed on a scale shorter than the exciton diffusion length of 10 nm, even when annealed above Tg. The temperature stability of APFO-3:PC61BM was also investigated with respect to the molecular weight of the polymer. The photovoltaic performance of these blends was found to be stable up to temperatures approaching the glass transition temperature, especially if a high molecular-weight APFO-3 grade was used.

     

    The crystallization of PC61BM was also investigated. Above Tg, PC61BM crystallization was found to commence, albeit slowly at temperatures close to Tg. At elevated temperatures instead, micrometer sized crystals were observed to form. It was also noted that illumination while annealing APFO-3:PC61BM thin films above Tg affected PC61BM crystallization, the origin of which is so far unclear although chemical degradation could be largely excluded.

  • 66.
    Bergqvist, Jonas
    Linköping University, Department of Physics, Chemistry and Biology, Biomolecular and Organic Electronics. Linköping University, Faculty of Science & Engineering.
    Optoelectrical Imaging Methods for Organic Photovoltaic Materials and Moduls2015Doctoral thesis, comprehensive summary (Other academic)
    Abstract [en]

    To achieve a high living standard for all people on Earth access to low cost energy is essential. The massive burning of fossil fuels must be drastically reduced if we are to avoid large changes of our climate. Solar cells are both technologically mature and have the potential to meet the huge demand for renewable energy in many countries. The prices for silicon solar cells have decreased rapidly during the course of this thesis and are now in grid parity in many countries.

    However, the potential for even lower energy costs has driven the research on polymer solar cells, a class of thin film solar cells. Polymer solar cells can be produced by roll to roll printing which potentially enables truly low cost solar cells. However, much research and development remain to reach that target.

    Polymer solar cells consist of a semiconducting composite material sandwiched between two electrodes, of which one is transparent, to let the light energy in to the semiconductor where it is converted to electric energy. The semiconductor comprise an intimate blend of polymer and fullerenes, where the nanostructure of this blend is crucial for the photo current extraction.

    To reach higher solar cell performance the dominating strategy is development and fine tuning of new polymers. To estimate their potential as solar cell materials their optical response have been determined by spectroscopic ellipsometry. Furthermore, optical simulations have been performed where the direction dependency of the optical response of the transparent electrode material PEDOT:PSS have been accounted for. The simulations show reduced electrode losses for light incident at large oblique angles.

    Moreover, we have shown that a gentle annealing of the active layer induces a local conformational changes of an amorphous polymer that is beneficial for solar cell performance. The active layer is deposited from solution where the drying kinetics determine the final nanostructure. We have shown that using in-situ photoluminescence phase separation can be detected during the drying process while a reflectance method have been developed to image lateral variations of solvent evaporation rate.

    Imaging methods are important tools to detect performance variations over the solar cell area. For this purpose an intermodulation based photo current imaging method have been developed to qualitatively differentiate the major photo current loss mechanisms. In addition, a 1D LED-array photo current imaging method have been developed and verified for high speed in-line characterization of printed organic solar modules.

    List of papers
    1. Comparison of selenophene and thienothiophene incorporation into pentacyclic lactam-based conjugated polymers for organic solar cells
    Open this publication in new window or tab >>Comparison of selenophene and thienothiophene incorporation into pentacyclic lactam-based conjugated polymers for organic solar cells
    Show others...
    2015 (English)In: Polymer Chemistry, ISSN 1759-9954, E-ISSN 1759-9962, Vol. 6, no 42, p. 7402-7409Article in journal (Refereed) Published
    Abstract [en]

    In this work, we compare the effect of incorporating selenophene versus thienothiophene spacers into pentacyclic lactam-based conjugated polymers for organic solar cells. The two cyclic lactam-based copolymers were obtained via a new synthetic method for the lactam moiety. Selenophene incorporation results in a broader and red-shifted optical absorption while retaining a deep highest occupied molecular orbital level, whereas thienothienophene incorporation results in a blue-shifted optical absorption. Additionally, grazing-incidence wide angle X-ray scattering data indicates edge- and face-on solid state order for the selenophene-based polymer as compared to the thienothiophene-based polymer, which orders predominantly edge-on with respect to the substrate. In polymer : PC71BM bulk heterojunction solar cells both materials show a similar open-circuit voltage of similar to 0.80-0.84 V, however the selenophene-based polymer displays a higher fill factor of similar to 0.70 vs. similar to 0.65. This is due to the partial face-on backbone orientation of the selenophene-based polymer, leading to a higher hole mobility, as confirmed by single-carrier diode measurements, and a concomitantly higher fill factor. Combined with improved spectral coverage of the selenophene-based polymer, as confirmed by quantum efficiency experiments, it offers a larger short-circuit current density of similar to 12 mA cm(-2). Despite the relatively low molecular weight of both materials, a very robust power conversion efficiency similar to 7% is achieved for the selenophene-based polymer, while the thienothiophene-based polymer demonstrates only a moderate maximum PCE of similar to 5.5%. Hence, the favorable effects of selenophene incorporation on the photovoltaic performance of pentacyclic lactam-based conjugated polymers are clearly demonstrated.

    Place, publisher, year, edition, pages
    ROYAL SOC CHEMISTRY, 2015
    National Category
    Biological Sciences
    Identifiers
    urn:nbn:se:liu:diva-122675 (URN)10.1039/c5py01245g (DOI)000363214600007 ()
    Note

    Funding Agencies|Chalmers Areas of Advance Materials Science, Energy and Nanoscience and Nanotechnology; Swedish Research Council; Knut and Alice Wallenberg foundation; Swedish Energy Agency; South Australian government; NSF; NIH/NIGMS via NSF [DMR-1332208]

    Available from: 2015-11-16 Created: 2015-11-13 Last updated: 2017-12-01
    2. Uniaxial anisotropy in PEDOT:PSS electrodes enhances the photo current at oblique incidence in organic solar cells
    Open this publication in new window or tab >>Uniaxial anisotropy in PEDOT:PSS electrodes enhances the photo current at oblique incidence in organic solar cells
    2015 (English)Manuscript (preprint) (Other academic)
    Abstract [en]

    In this work an uniaxial anisotropic treatment of the transparent conductor PEDOT:PSS is included in the transfer matrix method (TMM), used to calculate the optical power dissipation in organic solar cells. PEDOT:PSS is known to be anisotropic and exhibit a weaker absorption and lower refractive index in the out of plane direction. For p-polarized light at large oblique incidence the inclusion of anisotropy show a gain of over 10% for the maximum photocurrent as compared to an isotropic treatment. Due to the interference in devices with reflecting bottom electrodes, the active layer absorption gain is not always occurring for the wavelengths with highest dichroism. This work show that using PEDOT:PSS as top electrode further strengthens the argument that thin film solar cells perform better than their silicon counterparts under oblique incidence. We also confirm previous studies showing that the optical interference maxima is shifted to slightly thicker films for oblique incidence for solar cells with reflective bottom electrodes.

    National Category
    Physical Sciences Electrical Engineering, Electronic Engineering, Information Engineering
    Identifiers
    urn:nbn:se:liu:diva-123031 (URN)
    Available from: 2015-12-02 Created: 2015-12-02 Last updated: 2015-12-03Bibliographically approved
    3. In situ reflectance imaging of organic thin film formation from solution deposition
    Open this publication in new window or tab >>In situ reflectance imaging of organic thin film formation from solution deposition
    Show others...
    2013 (English)In: Solar Energy Materials and Solar Cells, ISSN 0927-0248, E-ISSN 1879-3398, Vol. 114, p. 89-98Article in journal (Refereed) Published
    Abstract [en]

    In this work we present reflectance imaging as a suitable method for in situ monitoring of the drying process of film formation for organic photovoltaics (OPV) over large areas, as well as for lab-scale spin-coating. The drying wet film is illuminated with a narrow bandwidth LED with the specularly reflected light recorded by a video camera as the film dries and forms the active layer of the OPV cell. The interference fringes generated by the thinning wet film can be used to measure the rate of solvent evaporation and the drying time. Subsequent mapping elucidates variations in drying conditions over the substrate, which lead to variations in morphology formation. The technique is suitable for tracking thickness variations of the dry film, with a sensitivity of 10 nm, by comparing the intensity of the reflected light from the dry film to simulated interference conditions calculated for each thickness. The drying process is furthermore accurately simulated by an optical model considering the changes in refractive index as the amount of solvent decreases with respect to the solid content. This non-invasive in situ method represents an important monitoring tool for future large scale OPV manufacturing where high performing morphologies with uniform thickness have to be formed over very large areas.

    Place, publisher, year, edition, pages
    Elsevier, 2013
    Keywords
    Reflectance imaging, Process control, Blade coating, Spin coating, Evaporation, OPV
    National Category
    Engineering and Technology
    Identifiers
    urn:nbn:se:liu:diva-95498 (URN)10.1016/j.solmat.2013.02.030 (DOI)000319486700013 ()
    Note

    Funding Agencies|Knut and Alice Wallenberg foundation||Swedish Energy Agency||

    Available from: 2013-07-05 Created: 2013-07-05 Last updated: 2017-12-06
    4. Lateral Phase Separation Gradients in Spin-Coated Thin Films of High-Performance Polymer: Fullerene Photovoltaic Blends
    Open this publication in new window or tab >>Lateral Phase Separation Gradients in Spin-Coated Thin Films of High-Performance Polymer: Fullerene Photovoltaic Blends
    Show others...
    2011 (English)In: Advanced Functional Materials, ISSN 1616-301X, E-ISSN 1616-3028, Vol. 21, no 16, p. 3169-3175Article in journal (Refereed) Published
    Abstract [en]

    In this study, it is demonstrated that a finer nanostructure produced under a rapid rate of solvent removal significantly improves charge separation in a high-performance polymer: fullerene bulk-heterojunction blend. During spin-coating, variations in solvent evaporation rate give rise to lateral phase separation gradients with the degree of coarseness decreasing away from the center of rotation. As a result, across spin-coated thin films the photocurrent at the first interference maximum varies as much as 25%, which is much larger than any optical effect. This is investigated by combining information on the surface morphology of the active layer imaged by atomic force microscopy, the 3D nanostructure imaged by electron tomography, film formation during the spin coating process imaged by optical interference and photocurrent generation distribution in devices imaged by a scanning light pulse technique. The observation that the nanostructure of organic photovoltaic blends can strongly vary across spin-coated thin films will aid the design of solvent mixtures suitable for high molecular-weight polymers and of coating techniques amenable to large area processing.

    Place, publisher, year, edition, pages
    Wiley-VCH Verlag Berlin, 2011
    National Category
    Engineering and Technology
    Identifiers
    urn:nbn:se:liu:diva-70526 (URN)10.1002/adfm.201100566 (DOI)000294166200019 ()
    Note

    Funding Agencies|Swedish Energy Agency||Spanish Ministerio de Ciencia e Innovacion||

    Available from: 2011-09-12 Created: 2011-09-12 Last updated: 2017-12-08Bibliographically approved
    5. Time-resolved morphology formation of solution cast polymer: fullerene blends revealed by in-situ photoluminescence spectroscopy
    Open this publication in new window or tab >>Time-resolved morphology formation of solution cast polymer: fullerene blends revealed by in-situ photoluminescence spectroscopy
    Show others...
    2015 (English)Manuscript (preprint) (Other academic)
    Abstract [en]

    The nanoscale morphology of the photo-active layer in organic solar cells is critical for device efficiency. The photoactive layer is cast from solution and during drying both the polymer and the fullerene self-assemble to form a blend. Here, we introduce in-situ spectroscopic photoluminescence (PL) combined with laser reflectometry to monitor the drying process of an amorphous polymer:fullerene blend. When casting only the pristine components (polymer or PCBM only), the strength of PL emission is proportional to the solid content of the drying solution, and both kinetics reveal a rapid aggregation onset at the final stage of film drying. On the contrary, when casting polymer:fullerene blends, the strength of PL emission is proportional to the wet film thickness and reveals polymer/fullerene charge transfer (CT) already at the earliest stages of film drying, i.e. in dilute solutions. The proposed method allows to detect polymer/fullerene phase separation during film casting – from a reduction in the PL quenching rate as the film dries. Poor solvents lead to phase separation already at early stages of film drying (low solid content), resulting in a coarse final morphology as confirmed by atomic force microscopy (AFM). We therefore anticipate that the proposed method will be an important tool in the future development of processing inks, not only for solution-cast polymer:fullerene solar cells but also for organic heterojunctions in general.

    National Category
    Physical Sciences Electrical Engineering, Electronic Engineering, Information Engineering
    Identifiers
    urn:nbn:se:liu:diva-123032 (URN)
    Available from: 2015-12-02 Created: 2015-12-02 Last updated: 2015-12-03
    6. Sub-glass transition annealing enhances polymer solar cell performance
    Open this publication in new window or tab >>Sub-glass transition annealing enhances polymer solar cell performance
    Show others...
    2014 (English)In: Journal of Materials Chemistry A, ISSN 2050-7488, Vol. 2, no 17, p. 6146-6152Article in journal (Refereed) Published
    Abstract [en]

    Thermal annealing of non-crystalline polymer: fullerene blends typically results in a drastic decrease in solar cell performance. In particular aggressive annealing above the glass transition temperature results in a detrimental coarsening of the blend nanostructure. We demonstrate that mild annealing below the glass transition temperature is a viable avenue to control the nanostructure of a non-crystalline thiophene-quinoxaline copolymer: fullerene blend. Direct imaging methods indicate that coarsening of the blend nanostructure can be avoided. However, a combination of absorption and luminescence spectroscopy reveals that local changes in the polymer conformation as well as limited fullerene aggregation are permitted to occur. As a result, we are able to optimise the solar cell performance evenly across different positions of the coated area, which is a necessary criterion for large-scale, high throughput production.

    Place, publisher, year, edition, pages
    Royal Society of Chemistry, 2014
    National Category
    Engineering and Technology
    Identifiers
    urn:nbn:se:liu:diva-106302 (URN)10.1039/c3ta14165a (DOI)000333580700024 ()
    Available from: 2014-05-06 Created: 2014-05-05 Last updated: 2015-12-03Bibliographically approved
    7. New method for lateral mapping of bimolecular recombination in thin film organic solar cells
    Open this publication in new window or tab >>New method for lateral mapping of bimolecular recombination in thin film organic solar cells
    Show others...
    2016 (English)In: Progress in Photovoltaics, ISSN 1062-7995, E-ISSN 1099-159X, Vol. 24, no 8, p. 1096-1108Article in journal (Refereed) Published
    Abstract [en]

    The best organic solar cells are limited by bimolecular recombination. Tools to study these losses are available; however, they are only developed for small area (laboratory-scale) devices and are not yet available for large area (production-scale) devices. Here we introduce the Intermodulation Light Beam-Induced Current (IMLBIC) technique, which allows simultaneous spatial mapping of both the amount of extracted photocurrent and the bimolecular recombination over the active area of a solar cell. We utilize the second-order non-linear dependence on the illumination intensity as a signature for bimolecular recombination. Using two lasers modulated with different frequencies, we record the photocurrent response at each modulation frequency and the bimolecular recombination in the second-order intermodulation response at the sum and difference of the two frequencies. Drift-diffusion simulations predict a unique response for different recombination mechanisms. We successfully verify our approach by studying solar cells known to have mainly bimolecular recombination and thus propose this method as a viable tool for lateral detection and characterization of the dominant recombination mechanisms in organic solar cells. We expect that IMLBIC will be an important future tool for characterization and detection of recombination losses in large area organic solar cells.

    Place, publisher, year, edition, pages
    John Wiley & Sons, 2016
    Keywords
    Organic photovoltaics, imaging, photocurrent, bimolecular recombination, light beam induced current, LBIC, intermodulation
    National Category
    Physical Sciences
    Identifiers
    urn:nbn:se:liu:diva-123033 (URN)10.1002/pip.2770 (DOI)000380164100007 ()
    Note

    Funding agencies|Swedish Research Council; Swedish Energy Agency; the Knut and Alice Wallenberg foundation through a Wallenberg Scholar grant to O.I

    At the time for thesis presentation publication was in status: Manuscript

    Available from: 2015-12-02 Created: 2015-12-02 Last updated: 2017-12-01Bibliographically approved
    8. LED array scanner for inline characterization of thin film photovoltaic modules
    Open this publication in new window or tab >>LED array scanner for inline characterization of thin film photovoltaic modules
    2016 (English)In: Solar Energy Materials and Solar Cells, ISSN 0927-0248, E-ISSN 1879-3398, Vol. 157, no 17, p. 1057-1064Article in journal (Refereed) Published
    Abstract [en]

    Thin film solar cells, and in particular printed organic solar cells, offer a potential route to a low cost power generation from sunlight. However, manufacturing these solar cells rapidly generates large areas that have to be characterized, preferably in-line for a direct feed back in the production process. Here we introduce the LEDimage, a LED array illumination induced photocurrent method suitable for high speed inline characterization and defect detection of organic solar cell modules. The LEDimage enables simultaneous illumination of all connected subcells without additional bias light. Each LED in the array is amplitude modulated at an individual frequency and the photocurrent response is Fourier transformed to generate a photocurrent map. Furthermore, the LEDimage can be used as a hand scanner for fast device characterization. We expect that LEDimage can be an effective research and industry tool for characterization of large area thin film solar cells.

    Place, publisher, year, edition, pages
    Elsevier, 2016
    National Category
    Physical Sciences
    Identifiers
    urn:nbn:se:liu:diva-123034 (URN)10.1016/j.solmat.2016.08.010 (DOI)000384391700127 ()
    Note

    Funding agencies: Swedish Energy Agency [2012-004594, 30032-3]; Knut and Alice Wallenberg foundation [2010.0053]

    Available from: 2015-12-02 Created: 2015-12-02 Last updated: 2017-12-01Bibliographically approved
  • 67.
    Bergqvist, Jonas
    et al.
    Linköping University, Department of Physics, Chemistry and Biology, Biomolecular and Organic Electronics. Linköping University, The Institute of Technology.
    Arwin, Hans
    Linköping University, Department of Physics, Chemistry and Biology, Applied Optics . Linköping University, The Institute of Technology.
    Inganäs, Olle
    Linköping University, Department of Physics, Chemistry and Biology, Biomolecular and Organic Electronics. Linköping University, The Institute of Technology.
    Determination of optical constants and phase transition temperatures in polymer fullerene thin films for polymer solar cells2012Conference paper (Other academic)
    Abstract [en]

    Plastic photovoltaics combining semiconducting polymers with fullerene derivatives have the potentialto become the first cost efficient solar cells able to compete with fossil fuels. The maximum powerconversion efficiency is already 8.3%[1] , and new polymers arrive frequently in the search for efficienciesof 10%. As a first step in the screening of candidate materials, the optical constants of the purepolymer as well as the polymer blend with fullerenes are determined from Variable Angle SpectroscopicEllipsometry (VASE), using Tauc-Lorentz oscillator models, throughout the solar spectrum. Thesemodels are then used to predict the upper limits to photocurrent generation in devices, in transfermatrix simulations of the multilayer thin film photovoltaic devices. This forms an essential step in thechoice of materials for optimization in devices.Materials optics measurements are also used to deduce the phase diagram of polymer and polymerblend films. The glass transition temperature is very important for plastic solar cells and mustbe higher than the 80C a device can reach to avoid degradation during operation. Temperaturedependent ellipsometric measurements has proven to be a feasible way to determine phase transitionsin polymer thin films[2] . These transitions are displayed as a sudden change of the volumetricexpansion coefficient, and are manifested by an abrupt increase of thickness at the phase transitiontemperature. For thickness determination a Cauchy model is applied to the transparent infrared partof the spectra.References1. Z. He, C. Zhong, X. Huang, W-Y. Wong, H. Wu, L. Chen, S. Su, Y Cao, Advanced Materials 23, 4636(2011)2. M. Campoy-Quiles, P.G. Etchegoin, D.D.C. Bradley, Synthetic Metals 155, 279(2005)

  • 68.
    Bergqvist, Jonas
    et al.
    Linköping University, Department of Physics, Chemistry and Biology, Biomolecular and Organic Electronics. Linköping University, The Institute of Technology.
    Arwin, Hans
    Linköping University, Department of Physics, Chemistry and Biology, Applied Optics . Linköping University, The Institute of Technology.
    Inganäs, Olle
    Linköping University, Department of Physics, Chemistry and Biology, Biomolecular and Organic Electronics. Linköping University, The Institute of Technology.
    In situ reflectance imaging of organic thin film formation from solution2012Conference paper (Other academic)
  • 69.
    Bergqvist, Jonas
    et al.
    Linköping University, Department of Physics, Chemistry and Biology, Biomolecular and Organic Electronics. Linköping University, Faculty of Science & Engineering.
    Arwin, Hans
    Linköping University, Department of Physics, Chemistry and Biology, Applied Optics . Linköping University, Faculty of Science & Engineering.
    Inganäs, Olle
    Linköping University, Department of Physics, Chemistry and Biology, Biomolecular and Organic Electronics. Linköping University, Faculty of Science & Engineering.
    Uniaxial anisotropy in PEDOT:PSS electrodes enhances the photo current at oblique incidence in organic solar cells2015Manuscript (preprint) (Other academic)
    Abstract [en]

    In this work an uniaxial anisotropic treatment of the transparent conductor PEDOT:PSS is included in the transfer matrix method (TMM), used to calculate the optical power dissipation in organic solar cells. PEDOT:PSS is known to be anisotropic and exhibit a weaker absorption and lower refractive index in the out of plane direction. For p-polarized light at large oblique incidence the inclusion of anisotropy show a gain of over 10% for the maximum photocurrent as compared to an isotropic treatment. Due to the interference in devices with reflecting bottom electrodes, the active layer absorption gain is not always occurring for the wavelengths with highest dichroism. This work show that using PEDOT:PSS as top electrode further strengthens the argument that thin film solar cells perform better than their silicon counterparts under oblique incidence. We also confirm previous studies showing that the optical interference maxima is shifted to slightly thicker films for oblique incidence for solar cells with reflective bottom electrodes.

  • 70.
    Bergqvist, Jonas
    et al.
    Linköping University, Department of Physics, Chemistry and Biology, Biomolecular and Organic Electronics. Linköping University, Faculty of Science & Engineering.
    Arwin, Hans
    Linköping University, Department of Physics, Chemistry and Biology, Thin Film Physics. Linköping University, Faculty of Science & Engineering.
    Inganäs, Olle
    Linköping University, Department of Physics, Chemistry and Biology, Biomolecular and Organic Electronics. Linköping University, Faculty of Science & Engineering.
    Uniaxial Anisotropy in PEDOT:PSS Electrodes Enhances the Photocurrent at Oblique Incidence in Organic Solar Cells2018In: ACS Photonics, E-ISSN 2330-4022, Vol. 5, no 8, p. 3023-3030Article in journal (Refereed)
    Abstract [en]

    PEDOT:PSS is a well studied organic conductor, commonly used as a transparent electrode material in printed organic devices such as organic solar cells. PEDOT:PSS thin films are known to be uniaxially anisotropic and exhibit a lower extinction coefficient and lower refractive index in the out of plane direction. To determine the maximum attainable photocurrent in thin film solar cells, the optical power dissipation can be calculated by the transfer matrix method. However, until now the anisotropic properties of PEDOT:PSS films have not been included in the model. In this work we have included an uniaxial anisotropic treatment of PEDOT:PSS films. We investigate reversed and semitransparent solar cells, with aluminum and PEDOT:PSS respectively as the second electrode and PEDOT:PSS as the top electrode, as compared to devices with isotropic PEDOT:PSS electrodes. For p-polarized light at large oblique incidence the inclusion of anisotropy shows a gain of over 7% for the maximum photocurrent in reversed solar cells. In semitransparent solar cells the photocurrent enhancement reaches 4-5% for p-polarized light. However, an enhancement of optical power dissipation and thus photocurrent generation of close to 40% is calculated for wavelengths close to the absorber bandgap. This work shows that for correct calculations of optical power dissipation in devices with PEDOT:PSS electrodes anisotropy should be included in the optical model. This will be especially important to determine the daily energy output of organic solar cells as their expected first markets are on building facades and indoor applications with larger fractions of diffuse light at large oblique incidence.

  • 71.
    Bergqvist, Jonas
    et al.
    Linköping University, Department of Physics, Chemistry and Biology, Biomolecular and Organic Electronics. Linköping University, The Institute of Technology.
    Lindqvist, Camilla
    Chalmers, Sweden .
    Backe, Olof
    Chalmers, Sweden .
    Ma, Zaifei
    Linköping University, Department of Physics, Chemistry and Biology, Biomolecular and Organic Electronics. Linköping University, The Institute of Technology.
    Tang, Zheng
    Linköping University, Department of Physics, Chemistry and Biology, Biomolecular and Organic Electronics. Linköping University, The Institute of Technology.
    Tress, Wolfgang
    Linköping University, Department of Physics, Chemistry and Biology, Biomolecular and Organic Electronics. Linköping University, The Institute of Technology.
    Gustafsson, Stefan
    Chalmers, Sweden .
    Wang, Ergang
    Chalmers, Sweden .
    Olsson, Eva
    Chalmers, Sweden .
    Andersson, Mats R.
    Chalmers, Sweden .
    Inganäs, Olle
    Linköping University, Department of Physics, Chemistry and Biology, Biomolecular and Organic Electronics. Linköping University, The Institute of Technology.
    Müller, Christian
    Chalmers, Sweden .
    Sub-glass transition annealing enhances polymer solar cell performance2014In: Journal of Materials Chemistry A, ISSN 2050-7488, Vol. 2, no 17, p. 6146-6152Article in journal (Refereed)
    Abstract [en]

    Thermal annealing of non-crystalline polymer: fullerene blends typically results in a drastic decrease in solar cell performance. In particular aggressive annealing above the glass transition temperature results in a detrimental coarsening of the blend nanostructure. We demonstrate that mild annealing below the glass transition temperature is a viable avenue to control the nanostructure of a non-crystalline thiophene-quinoxaline copolymer: fullerene blend. Direct imaging methods indicate that coarsening of the blend nanostructure can be avoided. However, a combination of absorption and luminescence spectroscopy reveals that local changes in the polymer conformation as well as limited fullerene aggregation are permitted to occur. As a result, we are able to optimise the solar cell performance evenly across different positions of the coated area, which is a necessary criterion for large-scale, high throughput production.

  • 72.
    Bergqvist, Jonas
    et al.
    Linköping University, Department of Physics, Chemistry and Biology, Biomolecular and Organic Electronics. Linköping University, The Institute of Technology.
    Mauger, Scott
    Linköping University, Department of Physics, Chemistry and Biology, Biomolecular and Organic Electronics. Linköping University, The Institute of Technology.
    Tvingstedt, Kristofer
    Linköping University, Department of Physics, Chemistry and Biology, Biomolecular and Organic Electronics. Linköping University, The Institute of Technology.
    Arwin, Hans
    Linköping University, Department of Physics, Chemistry and Biology, Applied Optics . Linköping University, The Institute of Technology.
    Inganäs, Olle
    Linköping University, Department of Physics, Chemistry and Biology, Biomolecular and Organic Electronics. Linköping University, The Institute of Technology.
    In situ reflectance imaging of organic thin film formation from solution deposition2013In: Solar Energy Materials and Solar Cells, ISSN 0927-0248, E-ISSN 1879-3398, Vol. 114, p. 89-98Article in journal (Refereed)
    Abstract [en]

    In this work we present reflectance imaging as a suitable method for in situ monitoring of the drying process of film formation for organic photovoltaics (OPV) over large areas, as well as for lab-scale spin-coating. The drying wet film is illuminated with a narrow bandwidth LED with the specularly reflected light recorded by a video camera as the film dries and forms the active layer of the OPV cell. The interference fringes generated by the thinning wet film can be used to measure the rate of solvent evaporation and the drying time. Subsequent mapping elucidates variations in drying conditions over the substrate, which lead to variations in morphology formation. The technique is suitable for tracking thickness variations of the dry film, with a sensitivity of 10 nm, by comparing the intensity of the reflected light from the dry film to simulated interference conditions calculated for each thickness. The drying process is furthermore accurately simulated by an optical model considering the changes in refractive index as the amount of solvent decreases with respect to the solid content. This non-invasive in situ method represents an important monitoring tool for future large scale OPV manufacturing where high performing morphologies with uniform thickness have to be formed over very large areas.

  • 73.
    Bergqvist, Jonas
    et al.
    Linköping University, Department of Physics, Chemistry and Biology, Biomolecular and Organic Electronics. Linköping University, Faculty of Science & Engineering.
    Melianas, Armantas
    Linköping University, Department of Physics, Chemistry and Biology, Biomolecular and Organic Electronics. Linköping University, Faculty of Science & Engineering.
    Andersson, Olof
    Linköping University, Department of Physics, Chemistry and Biology, Chemical and Optical Sensor Systems. Linköping University, Faculty of Science & Engineering.
    Lindqvist, Camilla
    INTERACT, Department of Engineering and Physics, Karlstad University, Karlstad, Sweden.
    Musumeci, Chiara
    Linköping University, Department of Physics, Chemistry and Biology, Biomolecular and Organic Electronics. Linköping University, Faculty of Science & Engineering.
    Inganäs, Olle
    Linköping University, Department of Physics, Chemistry and Biology, Biomolecular and Organic Electronics. Linköping University, Faculty of Science & Engineering.
    Time-resolved morphology formation of solution cast polymer: fullerene blends revealed by in-situ photoluminescence spectroscopy2015Manuscript (preprint) (Other academic)
    Abstract [en]

    The nanoscale morphology of the photo-active layer in organic solar cells is critical for device efficiency. The photoactive layer is cast from solution and during drying both the polymer and the fullerene self-assemble to form a blend. Here, we introduce in-situ spectroscopic photoluminescence (PL) combined with laser reflectometry to monitor the drying process of an amorphous polymer:fullerene blend. When casting only the pristine components (polymer or PCBM only), the strength of PL emission is proportional to the solid content of the drying solution, and both kinetics reveal a rapid aggregation onset at the final stage of film drying. On the contrary, when casting polymer:fullerene blends, the strength of PL emission is proportional to the wet film thickness and reveals polymer/fullerene charge transfer (CT) already at the earliest stages of film drying, i.e. in dilute solutions. The proposed method allows to detect polymer/fullerene phase separation during film casting – from a reduction in the PL quenching rate as the film dries. Poor solvents lead to phase separation already at early stages of film drying (low solid content), resulting in a coarse final morphology as confirmed by atomic force microscopy (AFM). We therefore anticipate that the proposed method will be an important tool in the future development of processing inks, not only for solution-cast polymer:fullerene solar cells but also for organic heterojunctions in general.

  • 74.
    Bergqvist, Jonas
    et al.
    Linköping University, Department of Physics, Chemistry and Biology, Biomolecular and Organic Electronics. Linköping University, Faculty of Science & Engineering.
    Tholén, Erik A.
    al Institute of Technology (EPFL), Station 6, Lausanne, Switzerland.
    Inganäs, Olle
    Linköping University, Department of Physics, Chemistry and Biology, Biomolecular and Organic Electronics. Linköping University, Faculty of Science & Engineering.
    LED array scanner for inline characterization of thin film photovoltaic modules2016In: Solar Energy Materials and Solar Cells, ISSN 0927-0248, E-ISSN 1879-3398, Vol. 157, no 17, p. 1057-1064Article in journal (Refereed)
    Abstract [en]

    Thin film solar cells, and in particular printed organic solar cells, offer a potential route to a low cost power generation from sunlight. However, manufacturing these solar cells rapidly generates large areas that have to be characterized, preferably in-line for a direct feed back in the production process. Here we introduce the LEDimage, a LED array illumination induced photocurrent method suitable for high speed inline characterization and defect detection of organic solar cell modules. The LEDimage enables simultaneous illumination of all connected subcells without additional bias light. Each LED in the array is amplitude modulated at an individual frequency and the photocurrent response is Fourier transformed to generate a photocurrent map. Furthermore, the LEDimage can be used as a hand scanner for fast device characterization. We expect that LEDimage can be an effective research and industry tool for characterization of large area thin film solar cells.

  • 75.
    Bergqvist, Jonas
    et al.
    Linköping University, Department of Physics, Chemistry and Biology, Biomolecular and Organic Electronics. Linköping University, Faculty of Science & Engineering.
    Tress, Wolfgang
    Laboratory of Photonics and Interfaces, Swiss Federal Institute of Technology (EPFL), Lausanne, Switzerland.
    Forchheimer, Daniel
    Nanostructure Physics, KTH Royal Institute of Technology, Stockholm, Sweden.
    Melianas, Armantas
    Linköping University, Department of Physics, Chemistry and Biology, Biomolecular and Organic Electronics. Linköping University, Faculty of Science & Engineering.
    Tang, Zheng
    Linköping University, Department of Physics, Chemistry and Biology, Biomolecular and Organic Electronics. Linköping University, Faculty of Science & Engineering.
    Haviland, David
    Nanostructure Physics, KTH Royal Institute of Technology, Stockholm, Sweden.
    Inganäs, Olle
    Linköping University, Department of Physics, Chemistry and Biology, Biomolecular and Organic Electronics. Linköping University, Faculty of Science & Engineering.
    New method for lateral mapping of bimolecular recombination in thin film organic solar cells2016In: Progress in Photovoltaics, ISSN 1062-7995, E-ISSN 1099-159X, Vol. 24, no 8, p. 1096-1108Article in journal (Refereed)
    Abstract [en]

    The best organic solar cells are limited by bimolecular recombination. Tools to study these losses are available; however, they are only developed for small area (laboratory-scale) devices and are not yet available for large area (production-scale) devices. Here we introduce the Intermodulation Light Beam-Induced Current (IMLBIC) technique, which allows simultaneous spatial mapping of both the amount of extracted photocurrent and the bimolecular recombination over the active area of a solar cell. We utilize the second-order non-linear dependence on the illumination intensity as a signature for bimolecular recombination. Using two lasers modulated with different frequencies, we record the photocurrent response at each modulation frequency and the bimolecular recombination in the second-order intermodulation response at the sum and difference of the two frequencies. Drift-diffusion simulations predict a unique response for different recombination mechanisms. We successfully verify our approach by studying solar cells known to have mainly bimolecular recombination and thus propose this method as a viable tool for lateral detection and characterization of the dominant recombination mechanisms in organic solar cells. We expect that IMLBIC will be an important future tool for characterization and detection of recombination losses in large area organic solar cells.

  • 76.
    Bergqvist, Jonas
    et al.
    Linköping University, Department of Physics, Chemistry and Biology, Biomolecular and Organic Electronics. Linköping University, The Institute of Technology.
    Tvingstedt, Kristofer
    Linköping University, Department of Physics, Chemistry and Biology, Biomolecular and Organic Electronics. Linköping University, The Institute of Technology.
    Arwin, Hans
    Linköping University, Department of Physics, Chemistry and Biology, Applied Optics . Linköping University, The Institute of Technology.
    Inganäs, Olle
    Linköping University, Department of Physics, Chemistry and Biology, Biomolecular and Organic Electronics. Linköping University, The Institute of Technology.
    In situ reflectance imaging of organic thin film formation from solution2012Conference paper (Other academic)
    Abstract [en]

    The rapid progress of organic photovoltaic devices during the last decade, with power conversion efficiencies now exceeding 8%, has brought the technology close to an industrial breakthrough. For polymer solar cells, roll to roll printing is desired to gain the production advantage. The formation of the photoactive material from solutions needs to be controlled and optimized. Therefore a suitable method to monitor the deposition process is needed as deviations of drying times1 and drying rates2 during the coating process have proven to generate morphology variations causing variations in photocurrent generation.

    Here we demonstrate how reflectance imaging can be used to monitor the drying process, both for spin coating and blade coating deposition. A blue LED is used as light source to generate specular reflections imaged by a CMOS camera. The thinning of the wet film can then be observed by thin film interference, and can be recorded for each pixel. This enables an estimation of the evaporation rate for each pixel mapped over the substrate. For spin coating the evaporation rate is shown to increase with the distance from the rotation center, whereas the air flow is the determining parameter during blade coating. By mapping the times when interference ceases, lateral variations in drying time are visualized. Furthermore the quenching of polymer photoluminescence during the drying process can be visualized, thus creating a possibility to estimate morphological variations. Moreover lateral thickness variations of the dry film can be visualized by scanning ellipsometry. After depositing a top electrode photocurrent images can be generated by a laser scanning method. This allows for a direct comparison of drying conditions and photocurrent generation.  The possibility to monitor the thin film formation as well as lateral variations in thickness in-situ by a non-invasive method, is an important step for future large scale applications where stable high performing generating morphologies have to be formed over large areas.

    1Schmidt-Hansberg, B.; Sanyal, M.; Klein, M.F.G.; Pfaff, M.; Schnabel, N.; Jaiser, S.; Vorobiev, A.; Müller, E.; Colsmann, A.; Scharfer, P.; Gerthsen, D.; Lemmer, U.; Barrena, E.; and Schabel, W., ACS Nano 5 , 2011, 8579-8590

    2 Hou, L.; Wang, E.; Bergqvist, J.; Andersson, V.B.; Wang, Z.; Müller, C.; Campoy-Quiles, M.; Andersson, M.R.; Zhang, F.; Inganäs, O.,Adv. Func. Mat. 21 , 2011, 3169–3175

  • 77.
    Bjorstrom, Cecilia M.
    et al.
    Karlstad University.
    Nilsson, Svante
    Karlstad University.
    Magnusson, Kjell O.
    Karlstad University.
    Moons, Ellen
    Karlstad University.
    Bernasik, Andrzej
    AGH-Univ. of Science and Technology .
    Rysz, Jakub
    Jagiellonian Univ.
    Budkowski, Andrzej
    Jagiellonian Univ.
    Zhang, Fengling
    Linköping University, Department of Physics, Chemistry and Biology, Biomolecular and Organic Electronics. Linköping University, The Institute of Technology.
    Inganäs, Olle
    Linköping University, Department of Physics, Chemistry and Biology, Biomolecular and Organic Electronics. Linköping University, The Institute of Technology.
    Andersson, Mats R.
    Chalmers.
    Influence of solvents and substrates on the morphology and the performance of low-bandgap polyfluorene: PCBM photovoltaic devices - art. no. 61921X2006In: Proceedings of SPIE, the International Society for Optical Engineering, ISSN 0277-786X, E-ISSN 1996-756X, Vol. 6192, p. X1921-X1921Article in journal (Refereed)
    Abstract [en]

    Spin-coated thin films of poly[(9,9-dioctylfluorenyl-2,7-diyl)-co-5,5-(4,7-di-2-thienyl-2,1,3-benzothiadiazole)] (APFO-3) blended with [6,6]-phenyl-C-61-butyric acid methyl ester (PCBM) are used as the active material in polymer photovoltaic cells. Such blends are known for their tendency to phase separate during film formation. Tuning the morphology of the blend in a controlled way is one possible road towards higher efficiency. We studied the effect of adding chlorobenzene to chloroform-based blend solutions before spin-coating on the conversion efficiency of APFO-3:PCBM photodiodes, and related that to the lateral and vertical morphology of thin films of the blend. The lateral morphology is imaged by atomic force microscopy (AFM) and the vertical compositional profile is obtained by dynamic secondary ion mass spectrometry (SIMS). The profiles reveal compositional variations consisting of multilayers of alternating polymer-rich and PCBM-rich domains in the blend film spin-coated from chloroform. The vertical compositional variations are caused by surface-directed spinodal waves and are frozen in during the rapid evaporation of a highly volatile solvent. With addition of the low-vapour pressure solvent chlorobenzene, a more homogeneous vertical composition is found. The conversion efficiency for solar cells of this blend was found to be optimal for chloroform: chlorobenzene mixtures with a volume-ratio of 80:1. We have also investigated the role of the substrate on the morphology. We found that blend films spin-coated from chloroform solutions on PEDOT:PSS-coated ITO show a similar compositional structure as the films on silicon, and that changing the substrate from silicon to gold only affects the vertical phase separation in a region close to the substrate interface.

  • 78.
    Bjorstrom Svanstrom, Cecilia M
    et al.
    Karlstad University, Department Phys and Elect Engn, S-65188 Karlstad, Sweden .
    Rysz, Jakub
    Jagiellonian University, Institute Phys, PL-30059 Krakow, Poland .
    Bernasik, Andrzej
    AGH University Science and Technology, Fac Phys and Appl Comp Science, PL-30059 Krakow, Poland .
    Budkowski, Andrzej
    Jagiellonian University, Institute Phys, PL-30059 Krakow, Poland .
    Zhang, Fengling
    Linköping University, Department of Physics, Chemistry and Biology, Biomolecular and Organic Electronics . Linköping University, The Institute of Technology.
    Inganäs, Olle
    Linköping University, Department of Physics, Chemistry and Biology, Biomolecular and Organic Electronics . Linköping University, The Institute of Technology.
    Andersson, Mats R
    Chalmers, Department Polymer Technology, S-41296 Gothenburg, Sweden .
    O Magnusson, Kjell
    Karlstad University, Department Phys and Elect Engn, S-65188 Karlstad, Sweden .
    J Benson-Smith, Jessica
    University London Imperial Coll Science Technology and Med, Department Phys, London SW7 2BW, England .
    Nelson, Jenny
    University London Imperial Coll Science Technology and Med, Department Phys, London SW7 2BW, England .
    Moons, Ellen
    Karlstad University, Department Phys and Elect Engn, S-65188 Karlstad, Sweden .
    Device Performance of APFO-3/PCBM Solar Cells with Controlled Morphology2009In: ADVANCED MATERIALS, ISSN 0935-9648, Vol. 21, no 43, p. 4398-+Article in journal (Refereed)
    Abstract [en]

    Polymer/fullerene solar cells with three different device structures: A) diffuse bilayer, B) spontaneously formed multilayer and C) vertically homogeneous thin films, are fabricated. The photocurrent/voltage performance is compared and it is found that the self-stratified structure (B) yields the highest energy conversion efficiency.

  • 79.
    Björk, Per
    Linköping University, Department of Physics, Chemistry and Biology, Biomolecular and Organic Electronics . Linköping University, The Institute of Technology.
    Biological Sensing and DNA Templated Electronics Using Conjugated Polymers2007Doctoral thesis, comprehensive summary (Other academic)
    Abstract [en]

    Conjugated polymers have been found useful in a wide range of applications such as solar cells, sensor elements and printed electronics, due to their optical and electronic properties. Functionalization with charged side chains has enabled water solubility, resulting in an enhanced interaction with biomolecules. This thesis focus on the emerging research fields, where these conjugated polyelectrolytes (CPEs) are combined with biomolecules for biological sensing and DNA nanowire assembling.

    CPEs have shown large potential in biomolecular detection where the optical read out is due to the geometrical alternation in the backbone and aggregation state. This thesis focused on transferring the biomolecular detection to a surface of CPEs. The characterization of the CPE layer show that a hydrogel can be formed, and how the layer can undergo geometrical changes upon external stimulus such as pH change. A selective sensor surface can be created by imprinting ssDNA or an antibody in the CPE layer. The discrimination for complementary DNA hybridization and specific antibody interaction can be monitored by surface plasmon resonance or quartz crystal microbalance. We have also taken the step out from the controlled test tube experiments to the complex environment of the cell showing the potential for staining of compartments and structures in live and fixed cell. Depending on the conditions and CPE used, cell nuclei, acidic vesicles and cytoskeleton structure can be visualized. Furthermore, the live staining shows no sign of toxic effect on cultured fibroblasts.

    CPEs can also be a valuable element when assembling electronics in the true nano regime. I have used DNA as building template due to its attractive size features, with a width of around 2 nm and a length scale in the µm regime, and the inbuilt base-paring recognition elements. This thesis shows how DNA can be decorated with CPEs and stretched on surfaces into a model for aligned semiconducting nanowire geometries. Not only making the template structures is of importance, but also how to place them on the correct surface position, i.e. on electrodes. Strategies for positioning DNA nanowires using transfer printing and surface energy patterning methods have therefore been developed in the thesis. The stretched DNA decorated with CPE also offers a way to further study the molecular binding interaction between the two molecules. Single molecular spectroscopy in combination with polarization has given information of the variation of the CPE binding along a DNA chain.

    List of papers
    1. Dynamics of complex formation between biological and luminescent conjugated polyelectrolytes - a surface plasmon resonance study
    Open this publication in new window or tab >>Dynamics of complex formation between biological and luminescent conjugated polyelectrolytes - a surface plasmon resonance study
    Show others...
    2005 (English)In: Biosensors and Bioelectronics, ISSN 0956-5663, Vol. 20, no 9, p. 1764-1771Article in journal (Refereed) Published
    Abstract [en]

    A water-soluble polythiophene, POWT, with zwitterionic peptide like side chains possess good characteristics for biosensor applications. The zwitterionic side chains of the polymer can couple to biomolecules via electrostatic and hydrogen bonding. This creates possibilities to imprint biomolecules to spin-coated polymer films with maintained functionality, and use the resulting matrix as a biosensor. Polymer-biomolecular interaction studies done with surface plasmon resonance (SPR) reveal a well performing sensor matrix with high affinity for DNA hybridizations as well as for protein detection. The responses are distinct and very specific. A directional dependence of antibodies binding to POWT layer has also been observed. The polymer films have also been characterized by optical methods. Emission and absorption measurements in different buffer systems confirm that the polymer matrix can undergo structural and conformational changes on surfaces. The dielectric function in the interval 300–800 nm of POWT is reported, based on variable angle spectroscopic ellipsometry. This modeling reveals that a considerable amount of water is included in the material. The polymer layer possesses the characteristics needed for biochip applications and micro array techniques.

    Keywords
    DNA; Protein; SPR; Sensor; Conjugated polymer; Ellipsometry
    National Category
    Engineering and Technology
    Identifiers
    urn:nbn:se:liu:diva-12725 (URN)10.1016/j.bios.2004.07.001 (DOI)
    Available from: 2007-12-07 Created: 2007-12-07 Last updated: 2014-04-08
    2. Hydrogels from a water-soluble Zwitterionic polythiophene: dynamics under pH change and biomolecular interactions observed using quartz crystal microbalance with dissipation monitoring
    Open this publication in new window or tab >>Hydrogels from a water-soluble Zwitterionic polythiophene: dynamics under pH change and biomolecular interactions observed using quartz crystal microbalance with dissipation monitoring
    2005 (English)In: Langmuir, ISSN 0743-7463, E-ISSN 1520-5827, Vol. 21, no 16, p. 7292-7298Article in journal (Refereed) Published
    Abstract [en]

    The water-soluble zwitterionic polythiophene, poly(3-((S)-5-amino-5- carboxyl-3-oxapentyl)-2,5-thiophene) hydrochloride (POWT), is a conjugated polyelectrolyte (CPE) with properties well suited for biochip applications. CPEs readily form hydrogels when exposed to water-based buffer solutions or biomolecule solutions. In this work, we used in situ quartz crystal microbalance with dissipation (QCM-D) monitoring to collect information on the interaction between POWT films exposed to buffers with different pH and POWT/DNA chains. Our data show that POWT swells significantly when exposed to low-pH buffers, such as pH 4 acetate, this is seen as an increase in thickness and decrease in viscosity obtained via a Voight-based modeling of combined f and D QCM-D measurements. The magnitude of thickness and viscosity change upon changing from a pH 10 carbonate buffer to pH 4 acetate is 100% increase in thickness and 50% decrease in viscosity. The response of the hydrogel under pH change is well correlated with fluorescence data from POWT films on glass. The state of the hydrogel is important during interaction with biomolecules; illustrated by the observation that a swollen CPE hydrogel adsorbs a higher amount of DNA than a compacted one. In agreement with previous results, the QCM-D data confirmed that the POWT/DNA hydrogel sense complementary DNA specifically and with negligible binding of noncomplementary DNA. These results are important for efficient constructions of biochips in water environments using this class of materials.

    National Category
    Engineering and Technology
    Identifiers
    urn:nbn:se:liu:diva-12726 (URN)10.1021/la050479e (DOI)
    Available from: 2007-12-07 Created: 2007-12-07 Last updated: 2017-12-14
    3. Conjugated polythiophene probes target lysosome-related acidic vacuoles in cultured primary cells
    Open this publication in new window or tab >>Conjugated polythiophene probes target lysosome-related acidic vacuoles in cultured primary cells
    Show others...
    2007 (English)In: Molecular and Cellular Probes, ISSN 0890-8508, Vol. 21, no 5-6, p. 329-337Article in journal (Refereed) Published
    Abstract [en]

    Conformation-sensitive optical probes for studying biological processes and structures are of great interest. The present work shows for the first time that conjugated polyelectrolyte (CPE) probes can be used for specific targeting of chromatin, nuclear and cytoplasmatic vesicles, and cytoskeletal components in a complex system of cultured cells. One of the probes could also be used for vital staining of live cells. When bound to different entities, the polythiophene derivative probes emitted light with different colors due to the unique spectral properties of these conformation sensitive probes. The physical pre-requisites for binding could also be exploited for characterization of the target. Unexpectedly, lysosome-related acidic vacuoles were targeted in cultured primary cells by both anionic, cationic, and zwitter-ionic polythiophene derivatives. Pre-treatment with Bafilomycin A1, a specific inhibitor of vacuolar-type H+-ATPase, caused redistribution of the staining. The targeting of lysosome-related acidic vesicles could not be demonstrated in transformed cells (melanoma, neuroblastoma, and prostate cancer cell lines), indicating a difference in the localization, structure, accessibility, or quantity of the target in cultured normal cells as compared with the malignant cell lines. The chemical nature of the conjugated polyelectrolyte complex in the cytoplasmatic vacuoles remains elusive.

    Keywords
    Conjugated polyelectrolyte; Polythiophene; Fibroblast; Lysosome; Cancer
    National Category
    Medical and Health Sciences
    Identifiers
    urn:nbn:se:liu:diva-12727 (URN)10.1016/j.mcp.2007.04.005 (DOI)
    Available from: 2007-12-07 Created: 2007-12-07 Last updated: 2014-04-08
    4. Soft lithographic printing of patterns of stretched DNA and DNA/electronic polymer wires by surface-energy modification and transfer
    Open this publication in new window or tab >>Soft lithographic printing of patterns of stretched DNA and DNA/electronic polymer wires by surface-energy modification and transfer
    2006 (English)In: Small, ISSN 1613-6810, Vol. 2, no 8-9, p. 1068-1074Article in journal (Refereed) Published
    Abstract [en]

    Aligned and stretched λ DNA is directed to specific locations on solid substrates. Surface-energy modification of glass substrates by using patterned polydimethylsiloxane (PDMS) stamps is used to direct DNA onto the surface-energy-modified micrometer-scale pattern through molecular combing. As an alternative, patterned and nonpatterned PDMS stamps modified with polymethylmethacrylate (PMMA) are utilized to direct the stretched DNA to the desired location and the results are compared. The DNA is elongated through molecular combing on the stamp and transfer printed onto the surfaces. PMMA-modified stamps show a more defined length of the stretched DNA, as compared to bare PDMS stamps. A combination of these two methods is also demonstrated. As an application example, transfer printing of DNA decorated with a semiconducting conjugated polyelectrolyte is shown. The resulting patterned localization of stretched DNA can be utilized for functional nanodevice structures, as well as for biological applications.

    Keywords
    conjugation, DNA, lithography, patterning, polymers
    National Category
    Engineering and Technology
    Identifiers
    urn:nbn:se:liu:diva-12728 (URN)10.1002/smll.200600126 (DOI)
    Available from: 2007-12-07 Created: 2007-12-07
    5. Single molecular imaging and spectroscopy of conjugated polyelectrolytes decorated on stretched aligned DNA
    Open this publication in new window or tab >>Single molecular imaging and spectroscopy of conjugated polyelectrolytes decorated on stretched aligned DNA
    2005 (English)In: Nano Letters, ISSN 1530-6984, Vol. 5, no 10, p. 1948-1953Article in journal (Refereed) Published
    Abstract [en]

    DNA is the prototype template for building nanoelectronic devices by self-assembly. The electronic functions are made possible by coordinating electronic polymer chains to DNA. This paper demonstrates two methods for fabrication of aligned and ordered DNA nanowires complexed with conjugated polyelectrolytes (CPEs). The complex can be formed either in solution prior to stretching or after stretching of the bare DNA on a surface. Molecular combing was used to stretch the complexes on surface energy patterned surfaces, and PMMA for the bare DNA. Single molecular spectroscopy, in fluorescence, and microscopy, in atomic force microscopy, give evidence for coordination of the short CPE chains to the aligned DNA.

    National Category
    Engineering and Technology
    Identifiers
    urn:nbn:se:liu:diva-12729 (URN)10.1021/nl051328z (DOI)
    Available from: 2007-12-07 Created: 2007-12-07 Last updated: 2009-02-13
    6. Structural studies of a well defined conjugated polyelectrolyte and its interaction with DNA
    Open this publication in new window or tab >>Structural studies of a well defined conjugated polyelectrolyte and its interaction with DNA
    Show others...
    Manuscript (Other academic)
    Identifiers
    urn:nbn:se:liu:diva-12730 (URN)
    Available from: 2007-12-07 Created: 2007-12-07 Last updated: 2010-01-13
  • 80.
    Björk, Per
    et al.
    Linköping University, Department of Physics, Chemistry and Biology, Biomolecular and Organic Electronics . Linköping University, The Institute of Technology.
    Herland, Anna
    Linköping University, Department of Physics, Chemistry and Biology, Biomolecular and Organic Electronics . Linköping University, The Institute of Technology.
    Hamedi, Mahiar
    Linköping University, Department of Physics, Chemistry and Biology, Biomolecular and Organic Electronics . Linköping University, The Institute of Technology.
    Inganäs, Olle
    Linköping University, Department of Physics, Chemistry and Biology, Biomolecular and Organic Electronics . Linköping University, The Institute of Technology.
    Biomolecular nanowires decorated by organic electronic polymers2010In: JOURNAL OF MATERIALS CHEMISTRY, ISSN 0959-9428, Vol. 20, no 12, p. 2269-2276Article in journal (Refereed)
    Abstract [en]

    We demonstrate the shaping and forming of organic electronic polymers into designer nanostructures using biomacromolecules. In order to create nanowires, nanohelixes and assemblies of these, we coordinate semiconducting or metallic polymers to biomolecular polymers in the form of DNA and misfolded proteins. Optoelectronic and electrochemical devices utilizing these shaped materials are discussed.

  • 81.
    Björk, Per
    et al.
    Linköping University, Department of Physics, Chemistry and Biology, Biomolecular and Organic Electronics . Linköping University, The Institute of Technology.
    Herland, Anna
    Linköping University, Department of Physics, Chemistry and Biology, Biomolecular and Organic Electronics . Linköping University, The Institute of Technology.
    Scheblykin, Ivan
    Department of Chemical.
    Inganäs, Olle
    Linköping University, Department of Physics, Chemistry and Biology, Biomolecular and Organic Electronics . Linköping University, The Institute of Technology.
    Single molecular imaging and spectroscopy of conjugated polyelectrolytes decorated on stretched aligned DNA2005In: Nano Letters, ISSN 1530-6984, Vol. 5, no 10, p. 1948-1953Article in journal (Refereed)
    Abstract [en]

    DNA is the prototype template for building nanoelectronic devices by self-assembly. The electronic functions are made possible by coordinating electronic polymer chains to DNA. This paper demonstrates two methods for fabrication of aligned and ordered DNA nanowires complexed with conjugated polyelectrolytes (CPEs). The complex can be formed either in solution prior to stretching or after stretching of the bare DNA on a surface. Molecular combing was used to stretch the complexes on surface energy patterned surfaces, and PMMA for the bare DNA. Single molecular spectroscopy, in fluorescence, and microscopy, in atomic force microscopy, give evidence for coordination of the short CPE chains to the aligned DNA.

  • 82.
    Björk, Per
    et al.
    Linköping University, Department of Physics, Chemistry and Biology, Biomolecular and Organic Electronics . Linköping University, The Institute of Technology.
    Holmström, Sven
    Inganäs, Olle
    Linköping University, Department of Physics, Chemistry and Biology, Biomolecular and Organic Electronics . Linköping University, The Institute of Technology.
    Soft lithographic printing of patterns of stretched DNA and DNA/electronic polymer wires by surface-energy modification and transfer2006In: Small, ISSN 1613-6810, Vol. 2, no 8-9, p. 1068-1074Article in journal (Refereed)
    Abstract [en]

    Aligned and stretched λ DNA is directed to specific locations on solid substrates. Surface-energy modification of glass substrates by using patterned polydimethylsiloxane (PDMS) stamps is used to direct DNA onto the surface-energy-modified micrometer-scale pattern through molecular combing. As an alternative, patterned and nonpatterned PDMS stamps modified with polymethylmethacrylate (PMMA) are utilized to direct the stretched DNA to the desired location and the results are compared. The DNA is elongated through molecular combing on the stamp and transfer printed onto the surfaces. PMMA-modified stamps show a more defined length of the stretched DNA, as compared to bare PDMS stamps. A combination of these two methods is also demonstrated. As an application example, transfer printing of DNA decorated with a semiconducting conjugated polyelectrolyte is shown. The resulting patterned localization of stretched DNA can be utilized for functional nanodevice structures, as well as for biological applications.

  • 83.
    Björk, Per
    et al.
    Linköping University, Department of Physics, Chemistry and Biology, Biomolecular and Organic Electronics. Linköping University, The Institute of Technology.
    Nilsson, Peter
    Linköping University, Department of Physics, Chemistry and Biology, Organic Chemistry. Linköping University, The Institute of Technology.
    Lenner, Liselotte
    Linköping University, Department of Clinical and Experimental Medicine, Clinical Chemistry. Linköping University, Faculty of Health Sciences.
    Kågedal, Bertil
    Linköping University, Department of Clinical and Experimental Medicine, Clinical Chemistry. Linköping University, Faculty of Health Sciences.
    Persson, Birgitta
    Linköping University, Department of Biomedicine and Surgery. Linköping University, Faculty of Health Sciences.
    Inganäs, Olle
    Linköping University, Department of Physics, Chemistry and Biology, Biomolecular and Organic Electronics. Linköping University, The Institute of Technology.
    Jonasson, Jon
    Linköping University, Department of Clinical and Experimental Medicine, Molecular and Immunological Pathology. Linköping University, Faculty of Health Sciences. Östergötlands Läns Landsting, Centre for Laboratory Medicine, Department of Clinical Pathology and Clinical Genetics.
    Conjugated polythiophene probes target lysosome-related acidic vacuoles in cultured primary cells2007In: Molecular and Cellular Probes, ISSN 0890-8508, Vol. 21, no 5-6, p. 329-337Article in journal (Refereed)
    Abstract [en]

    Conformation-sensitive optical probes for studying biological processes and structures are of great interest. The present work shows for the first time that conjugated polyelectrolyte (CPE) probes can be used for specific targeting of chromatin, nuclear and cytoplasmatic vesicles, and cytoskeletal components in a complex system of cultured cells. One of the probes could also be used for vital staining of live cells. When bound to different entities, the polythiophene derivative probes emitted light with different colors due to the unique spectral properties of these conformation sensitive probes. The physical pre-requisites for binding could also be exploited for characterization of the target. Unexpectedly, lysosome-related acidic vacuoles were targeted in cultured primary cells by both anionic, cationic, and zwitter-ionic polythiophene derivatives. Pre-treatment with Bafilomycin A1, a specific inhibitor of vacuolar-type H+-ATPase, caused redistribution of the staining. The targeting of lysosome-related acidic vesicles could not be demonstrated in transformed cells (melanoma, neuroblastoma, and prostate cancer cell lines), indicating a difference in the localization, structure, accessibility, or quantity of the target in cultured normal cells as compared with the malignant cell lines. The chemical nature of the conjugated polyelectrolyte complex in the cytoplasmatic vacuoles remains elusive.

  • 84.
    Björk, Per
    et al.
    Linköping University, Department of Physics, Chemistry and Biology, Biomolecular and Organic Electronics . Linköping University, The Institute of Technology.
    Persson, Nils-Krister
    Linköping University, Department of Physics, Chemistry and Biology, Biomolecular and Organic Electronics . Linköping University, The Institute of Technology.
    Nilsson, Peter
    Linköping University, Department of Physics, Chemistry and Biology, Biomolecular and Organic Electronics . Linköping University, The Institute of Technology.
    Åsberg, Peter
    Linköping University, Department of Physics, Chemistry and Biology, Biomolecular and Organic Electronics . Linköping University, The Institute of Technology.
    Inganäs, Olle
    Linköping University, Department of Physics, Chemistry and Biology, Biomolecular and Organic Electronics . Linköping University, The Institute of Technology.
    Dynamics of complex formation between biological and luminescent conjugated polyelectrolytes - a surface plasmon resonance study2005In: Biosensors and Bioelectronics, ISSN 0956-5663, Vol. 20, no 9, p. 1764-1771Article in journal (Refereed)
    Abstract [en]

    A water-soluble polythiophene, POWT, with zwitterionic peptide like side chains possess good characteristics for biosensor applications. The zwitterionic side chains of the polymer can couple to biomolecules via electrostatic and hydrogen bonding. This creates possibilities to imprint biomolecules to spin-coated polymer films with maintained functionality, and use the resulting matrix as a biosensor. Polymer-biomolecular interaction studies done with surface plasmon resonance (SPR) reveal a well performing sensor matrix with high affinity for DNA hybridizations as well as for protein detection. The responses are distinct and very specific. A directional dependence of antibodies binding to POWT layer has also been observed. The polymer films have also been characterized by optical methods. Emission and absorption measurements in different buffer systems confirm that the polymer matrix can undergo structural and conformational changes on surfaces. The dielectric function in the interval 300–800 nm of POWT is reported, based on variable angle spectroscopic ellipsometry. This modeling reveals that a considerable amount of water is included in the material. The polymer layer possesses the characteristics needed for biochip applications and micro array techniques.

  • 85.
    Björk, Per
    et al.
    Linköping University, Department of Physics, Chemistry and Biology, Biomolecular and Organic Electronics . Linköping University, The Institute of Technology.
    Thomsson, Daniel
    Lund University.
    Mirzov, Oleg
    Lund University.
    Andersson, Jens
    Linköping University, Department of Physics, Chemistry and Biology, Biomolecular and Organic Electronics . Linköping University, The Institute of Technology.
    Inganäs, Olle
    Linköping University, Department of Physics, Chemistry and Biology, Biomolecular and Organic Electronics . Linköping University, The Institute of Technology.
    Scheblykin , Ivan G
    Lund University.
    Oligothiophene Assemblies Defined by DNA Interaction: From Single Chains to Disordered Clusters2009In: SMALL, ISSN 1613-6810 , Vol. 5, no 1, p. 96-103Article in journal (Refereed)
    Abstract [en]

    The organization of conjugated polyelectrolytes (CPEs) interacting with biomolecules sets conditions for the biodetection of biological processes and identity, through the use of optical emission from the CPE. Herein, a well-defined CPE and its binding to DNA is studied. By using dynamic light scattering and circular dichroism spectroscopy, it is shown that the CPE forms a multimolecule ensemble in aqueous solution that is more than doubled it? size when interacting with a small DNA chain, while single chains are evident in ethanol. The related changes in the fluorescence spectra upon polymer aggregation are assigned to oscillator strength redistribution between vibronic transitions in weakly coupled H-aggregates. An enhanced single-molecule spectroscopy technique that allows full control of excitation and emission light polarization is applied to combed and decorated;,DNA chains. It is found that the organization of combed CPE-lambda DNA complexes (when dry on the surface) allows considerable variation of CPE distances and direction relative to the DNA chain. By analysis of the polarization data. energy transfer between the polymer chains in individual complexes is confirmed and their sizes estimated.

  • 86.
    Bliss, Martin
    et al.
    Loughborough Univ, England.
    Smith, Alex
    Loughborough Univ, England.
    Betts, Thomas R.
    Loughborough Univ, England.
    Baker, Jenny
    Swansea Univ, Wales.
    De Rossi, Francesca
    Swansea Univ, Wales.
    Bai, Sai
    Linköping University, Department of Physics, Chemistry and Biology, Biomolecular and Organic Electronics. Linköping University, Faculty of Science & Engineering. Univ Oxford, England.
    Watson, Trystan
    Swansea Univ, Wales.
    Snaith, Henry
    Univ Oxford, England.
    Gottschalg, Ralph
    Loughborough Univ, England; Fraunhofer Ctr Silicon Photovolta, Germany; Hsch Anhalt, Germany.
    Spectral Response Measurements of Perovskite Solar Cells2019In: IEEE Journal of Photovoltaics, ISSN 2156-3381, E-ISSN 2156-3403, Vol. 9, no 1, p. 220-226Article in journal (Refereed)
    Abstract [en]

    A new spectral response (SR) measurement routine is proposed that is universally applicable for all perovskite devices. It is aimed at improving measurement accuracy and repeatability of SR curves and current-voltage curve spectral mismatch factor (MMF) corrections. Frequency response, effects of preconditioning as well as dependency on incident light intensity and voltage load on SR measurements are characterized on two differently structured perovskite device types. It is shown that device preconditioning affects the SR shape, causing errors in spectral MMF corrections of up to 0.8% when using a reference cell with a good spectral match and a class A solar simulator. Wavelength dependent response to incident light intensity and voltage load is observed on both device types, which highlights the need to measure at short-circuit current and maximum power point to correct spectral mismatch. The method with recommendations given ensures that the correct measurement conditions are applied and measurements are corrected for instability in performance.

  • 87.
    Bolin, Maria
    et al.
    Linköping University, Department of Science and Technology. Linköping University, The Institute of Technology.
    Svennersten, Karl
    Karolinska Institute.
    Wang, Xiangjun
    Linköping University, Department of Physics, Chemistry and Biology, Biomolecular and Organic Electronics. Linköping University, The Institute of Technology.
    Chronakis, Ioannis S
    Industrial Research & Development Corporation.
    Richter-Dahlfors, Agneta
    Karolinska Institute.
    Jager, Edwin
    Linköping University, Department of Science and Technology. Linköping University, The Institute of Technology.
    Berggren, Magnus
    Linköping University, Department of Science and Technology. Linköping University, The Institute of Technology.
    Nano-fiber scaffold electrodes based on PEDOT for cell stimulation2009In: SENSORS AND ACTUATORS B-CHEMICAL, ISSN 0925-4005, Vol. 142, no 2, p. 451-456Article in journal (Refereed)
    Abstract [en]

    Electronically conductive and electrochemically active 3D-scaffolds based on electrospun poly(ethylene terephthalate) (PET) nano-fibers are reported. Vapour phase polymerization was employed to achieve an uniform and conformal coating of poly(3,4-ethylenedioxythiophene) doped with tosylate (PEDOT:tosylate) on the nano-fibers. The PEDOT coatings had a large impact on the wettability, turning the hydrophobic PET fibers super-hydrophilic. SH-SY5Y neuroblastoma cells were grown on the PEDOT coated fibers. The SH-SY5Y cells adhered well and showed healthy morphology. These electrically active scaffolds were used to induce Ca2+ signalling in SH-SY5Y neuroblastoma cells. PEDOT:tosylate coated nano-fibers represent a class of 3D host environments that combines excellent adhesion and proliferation for neuronal cells with the possibility to regulate their signalling.

  • 88.
    Bolognesi, A.
    et al.
    Ist. lo Stud. delle Macromolecole, CNR, Via E. Bassini 15, 20133 Milano, Italy.
    Giacometti, Schieroni A.
    Giacometti Schieroni, A., Ist. lo Stud. delle Macromolecole, CNR, Via E. Bassini 15, 20133 Milano, Italy.
    Botta, C.
    Ist. lo Stud. delle Macromolecole, CNR, Via E. Bassini 15, 20133 Milano, Italy.
    Marinelli, M.
    Ist. lo Stud. delle Macromolecole, CNR, Via E. Bassini 15, 20133 Milano, Italy.
    Mendichi, R.
    Ist. lo Stud. delle Macromolecole, CNR, Via E. Bassini 15, 20133 Milano, Italy.
    Rolandi, R.
    Ist. Naz. per la Fis. della Materiae, Dipartimento di Fisica, Università di Genova, Via Dodecaneso 33, 16146 Genova, Italy.
    Relini, A.
    Ist. Naz. per la Fis. della Materiae, Dipartimento di Fisica, Università di Genova, Via Dodecaneso 33, 16146 Genova, Italy.
    Inganäs, Olle
    Linköping University, The Institute of Technology. Linköping University, Department of Physics, Chemistry and Biology, Biomolecular and Organic Electronics .
    Theandher, M.
    High photoluminescence efficiency in substituted polythiophene aggregates2003In: Synthetic metals, ISSN 0379-6779, E-ISSN 1879-3290, Vol. 139, no 2, p. 303-310Article in journal (Refereed)
    Abstract [en]

    In this paper we discuss the optical (absorption and photoluminescence) and solvatochromic properties of a newly synthesized alternating copolymer based on poly(3-alkylthiophene) structure. In this copolymer an unsubstituted thiophene ring is linked to a 3-alkyl-substituted thiophene, the two repeating units being alternated in the copolymer chains. Moreover, a bulky group, THP, with high steric hindrance has been introduced in the side chain. This copolymer, designed to preserve the backbone planarity of polythiophenes and to prevent a close packing arrangement through the non-regioregular insertion of the bulky substituted monomer, shows high PL quantum yield in the solid state and in solution aggregates. The electroluminescence of this copolymer is reported for a simple single layer device. © 2003 Elsevier Science B.V. All rights reserved.

  • 89.
    Borgani, Riccardo
    et al.
    Royal Institute Technology, Sweden.
    Forchheimer, Daniel
    Royal Institute Technology, Sweden.
    Bergqvist, Jonas
    Linköping University, Department of Physics, Chemistry and Biology, Biomolecular and Organic Electronics. Linköping University, The Institute of Technology.
    Thoren, Per-Anders
    Royal Institute Technology, Sweden.
    Inganäs, Olle
    Linköping University, Department of Physics, Chemistry and Biology, Biomolecular and Organic Electronics. Linköping University, The Institute of Technology.
    Haviland, David B.
    Royal Institute Technology, Sweden.
    Intermodulation electrostatic force microscopy for imaging surface photo-voltage2014In: Applied Physics Letters, ISSN 0003-6951, E-ISSN 1077-3118, Vol. 105, no 14, p. 143113-Article in journal (Refereed)
    Abstract [en]

    We demonstrate an alternative to Kelvin Probe Force Microscopy for imaging surface potential. The open-loop, single-pass technique applies a low-frequency AC voltage to the atomic force microscopy tip while driving the cantilever near its resonance frequency. Frequency mixing due to the nonlinear capacitance gives intermodulation products of the two drive frequencies near the cantilever resonance, where they are measured with high signal to noise ratio. Analysis of this intermodulation response allows for quantitative reconstruction of the contact potential difference. We derive the theory of the method, validate it with numerical simulation and a control experiment, and we demonstrate its utility for fast imaging of the surface photo-voltage on an organic photovoltaic material.

  • 90.
    Bresel, Anders
    et al.
    Linköping University, Department of Physics, Chemistry and Biology, Biomolecular and Organic Electronics . Linköping University, The Institute of Technology.
    Persson, Bengt
    Linköping University, Department of Physics, Chemistry and Biology, Bioinformatics . Linköping University, The Institute of Technology.
    GenomeLKPG: A comprehensive proteome sequencedatabase for taxonomy studies2008Article in journal (Refereed)
    Abstract [en]

    Background: In order to perform taxonomically unbiased analyses of protein relationships, there is a need ofcomplete proteomes rather than databases with bias towards well characterized protein families. However, nocomprehensive resource of completed proteomes is currently available. Instead, the proteomes need to be down-loaded manually from di®erent servers, all using different filename conventions and fasta header formats.

    Results: We have developed a semi-automatic algorithm that retrieves complete proteomes from multiple FTP-servers and maps the species-speci¯c sequence entries to the NCBI taxonomy. The compiled data is provided ina sequence database named genomeLKPG.

    Conclusions: The usefulness of genomeLKPG is proven in several published taxonomical studies.

  • 91.
    Bäcklund, Fredrik
    Linköping University, Department of Physics, Chemistry and Biology, Biomolecular and Organic Electronics. Linköping University, Faculty of Science & Engineering.
    Preparation and Application of Functionalized Protein Fibrils2015Doctoral thesis, comprehensive summary (Other academic)
    Abstract [en]

    Many proteins have an innate ability to self-assemble into fibrous structures known as amyloid fibrils. From a material science perspective, fibrils have several interesting characteristics, including a high stability, a distinct shape and tunable surface properties. Such structures can be given additional properties through functionalization by other compounds such as fluorophores. Combination of fibrils with a function yielding compound can be achieved in several ways. Covalent bond attachment is specific, but cumbersome. External surface adhesion is nonspecific, but simple. However, in addition, internal non-covalent functionalization is possible. In this thesis, particular emphasis is put on internal functionalization of fibrils; by co-grinding fibril forming proteins with a hydrophobic molecule, a protein-hydrophobic compound molecule composite can be created that retains the proteins innate ability to form fibrils. Subsequently formed fibrils will thus have the structural properties of the protein fibril as well as the properties of the incorporated compound. The functionalization procedures used throughout this thesis are applicable for a wide range of chromophores commonly used for organic electronics and photonics. The methods developed and the prepared materials are useful for applications within optoelectronics as well as biomedicine.

    Regardless of the methodology of functionalization, using functionalized fibrils in a controlled fashion for material design requires an intimate understanding of the formation process and knowledge of the tools available to control not only the formation but also any subsequent macroscale assembly of fibrils. The development and application of such tools are described in several of the papers included in this thesis. With the required knowledge in hand, the possible influence of fibrils on the functionalizing agents, and vice versa, can be probed. The characteristic traits of the functionalized fibril can be customized and the resulting material can be organized and steered towards a specific shape and form. This thesis describes how control over the process of formation, functionalization and organization of functionalized fibrils can be utilized to influence the hierarchical assembly of fibrils – ranging from spherical structures to  spirals; the function – fluorescent or conducting; and macroscopic properties – optical birefringence and specific arrangement of functionalized fibrils in the solid state. In conclusion, the use of amyloid fibrils in material science has great potential. Herein is presented a possible route towards a fully bottom up approach ranging from the nanoscale to the macroscale.

    List of papers
    1. Controlling Amyloid Fibril Formation by Partial Stirring
    Open this publication in new window or tab >>Controlling Amyloid Fibril Formation by Partial Stirring
    2016 (English)In: Biopolymers, ISSN 0006-3525, E-ISSN 1097-0282, Vol. 105, no 5, p. 249-259Article in journal (Refereed) Published
    Abstract [en]

    Many proteins undergoes self-assembly into fibrillar structures known as amyloid fibrils. During the self-assembly process related structures, known as spherulites, can be formed. Herein we report a facile method where the balance between amyloid fibrils and spherulites can be controlled by stirring of the reaction mixture during the initial stages of the self-assembly process. Moreover, we report how this methodology can be used to prepare non-covalently functionalized amyloid fibrils. By stirring the reaction mixture continuously or for a limited time during the lag phase the fibril length, and hence the propensity to form liquid crystalline phases, can be influenced. This phenomena is utilized by preparing films consisting of aligned protein fibrils incorporating the laser dye Nile red. The resulting films display polarized Nile red fluorescence.

    Place, publisher, year, edition, pages
    Wiley-Blackwell, 2016
    National Category
    Organic Chemistry Biomaterials Science
    Identifiers
    urn:nbn:se:liu:diva-121017 (URN)10.1002/bip.22803 (DOI)000371690100001 ()
    Note

    Funding agencies:  Swedish Government [2009-00971]; Knut and Alice Wallenberg foundation

    Vid tiden för disputation förelåg publikationen endast som manuskript

    Available from: 2015-09-02 Created: 2015-09-02 Last updated: 2017-12-04Bibliographically approved
    2. Amyloid fibrils as dispersing agents for oligothiophenes: control of photophysical properties through nanoscale templating and flow induced fibril alignment
    Open this publication in new window or tab >>Amyloid fibrils as dispersing agents for oligothiophenes: control of photophysical properties through nanoscale templating and flow induced fibril alignment
    Show others...
    2014 (English)In: Journal of Materials Chemistry C, ISSN 2050-7526, E-ISSN 2050-7534, Vol. 2, no 37, p. 7811-7822Article in journal (Refereed) Published
    Abstract [en]

    Herein we report that protein fibrils formed from aggregated proteins, so called amyloid fibrils, serve as an excellent dispersing agent for hydrophobic oligothiophenes such as alpha-sexithiophene (6T). Furthermore, the protein fibrils are capable of orienting 6T along the fibril long axis, as demonstrated by flow-aligned linear dichroism spectroscopy and polarized fluorescence microscopy. The materials are prepared by solid state mixing of 6T with a protein capable of self-assembly. This results in a water soluble composite material that upon heating in aqueous acid undergoes self-assembly into protein fibrils non-covalently functionalized with 6T, with a typical diameter of 5-10 nm and lengths in the micrometre range. The resulting aqueous fibril dispersions are a readily available source of oligothiophenes that can be processed from aqueous solvent, and we demonstrate the fabrication of macroscopic structures consisting of aligned 6T functionalized protein fibrils. Due to the fibril induced ordering of 6T these structures exhibit polarized light emission.

    Place, publisher, year, edition, pages
    Royal Society of Chemistry, 2014
    National Category
    Biological Sciences
    Identifiers
    urn:nbn:se:liu:diva-111311 (URN)10.1039/c4tc00692e (DOI)000341458000013 ()
    Note

    Funding Agencies|Swedish Research Council [20114324]; Swedish Strategic Research Foundation (SSF); Knut and Alice Wallenberg foundation through a Wallenberg Scholar grant; Chalmers Area of Advance in Nanoscience and Nanotechnology; Swedish Government Strategic Research Area in Materials Science on Functional Materials at Linkoping University (Faculty Grant SFO-Mat-LiU) [2009-00971]

    Available from: 2014-10-14 Created: 2014-10-14 Last updated: 2017-12-05
    3. Development and Application of Methodology for Rapid Screening of Potential Amyloid Probes
    Open this publication in new window or tab >>Development and Application of Methodology for Rapid Screening of Potential Amyloid Probes
    2014 (English)In: ACS COMBINATORIAL SCIENCE, ISSN 2156-8952, Vol. 16, no 12, p. 721-729Article in journal (Refereed) Published
    Abstract [en]

    Herein, we demonstrate that it is possible to rapidly screen hydrophobic fluorescent aromatic molecules with regards to their properties as amyloid probes. By grinding the hydrophobic molecule with the amyloidogenic protein insulin, we obtained a water-soluble composite material. When this material is dissolved and exposed to conditions promoting amyloid formation, the protein aggregates into amyloid fibrils incorporating the hydrophobic molecule. As a result, changes in the fluorescence spectra of the hydrophobic molecule can be correlated to the formation of amyloid fibrils, and the suitability of the hydrophobic molecular skeleton as an amyloid probe can thus be assessed. As a result, we discovered two new amyloid probes, of which one is the well-known laser dye DCM. The grinding method can also be used for rapid preparation of novel composite materials between dyes and proteins, which can be used in materials science applications such as organic electronics and photonics.

    Place, publisher, year, edition, pages
    ACS Publications, 2014
    Keywords
    amyloid probes; rapid screening; fluorescent; aromatic molecules; laser dye DCM
    National Category
    Biological Sciences
    Identifiers
    urn:nbn:se:liu:diva-113169 (URN)10.1021/co5001212 (DOI)000346114600009 ()25383488 (PubMedID)
    Note

    Funding Agencies|Swedish Government Strategic Research Area in Materials Science on Functional Materials at Linkoping University [2009-00971]; Knut and Alice Wallenberg Foundation

    Available from: 2015-01-14 Created: 2015-01-12 Last updated: 2015-09-02
    4. Tuning the aqueous self-assembly process of insulin by a hydrophobic additive
    Open this publication in new window or tab >>Tuning the aqueous self-assembly process of insulin by a hydrophobic additive
    2015 (English)In: RSC ADVANCES, ISSN 2046-2069, Vol. 5, no 112, p. 92254-92262Article in journal (Refereed) Published
    Abstract [en]

    Biomolecular self-assembly is an efficient way of preparing soft-matter based materials. Herein we report a novel method, based on the use of insoluble additives in aqueous media, for influencing the self-assembly process. Due to their low solubility, the use of hydrophobic additives in aqueous media is problematic; however, by mixing the additive with the biomolecule in the solid state, prior to solvation, this problem can be circumvented. In the investigated self-assembly system, where bovine insulin self-assembles into spherical structures, the inclusion of the hydrophobic material α-sexithiophene (6T) results in significant changes in the self-assembly process. Under our reaction conditions, in the case of materials prepared from insulin-only the growth of spherulites typically stops at a diameter of 150μm. However, by adding 2 weight % of hydrophobic material, spherulite growth continues up to diameters in the mm-range. The spherulites incorporate 6T and are thus fluorescent. The method reported herein should be of interest to all scientists working in the field of self-assembly as the flexible materials preparation, based simply on co-grinding of commercially available materials, adds another option to influence the structure and properties of products formed by  self-assembly reactions.

    Place, publisher, year, edition, pages
    Royal Society of Chemistry, 2015
    National Category
    Organic Chemistry Biomaterials Science
    Identifiers
    urn:nbn:se:liu:diva-121018 (URN)10.1039/c5ra16144d (DOI)000364032500040 ()
    Note

    Funding agencies: Swedish Government Strategic Research Area in Materials Science on Functional Materials at Linkoping University (Faculty Grant SFO-Mat-LiU) [2009-00971]; Knut and Alice Wallenberg foundation

    Available from: 2015-09-02 Created: 2015-09-02 Last updated: 2015-12-03
    5. Convection Induced Air-Water Interface Assembly of Amyloid Fibrils
    Open this publication in new window or tab >>Convection Induced Air-Water Interface Assembly of Amyloid Fibrils
    (English)Manuscript (preprint) (Other academic)
    Abstract [en]

    We report that hydrophobically modified amyloid fibrils form macroscopic films at the air-water interface. The hydrophobically modified fibrils are prepared in a two step process. First bovine insulin is ground with a hydrophobic compound. The resulting material is dissolved in acidic water and heated to induce assembly into fibrils incorporating the hydrophobic compounds. Upon dilution followed by asymmetric heating, resulting in convection flow, the fibrills form highly ordered films with thicknesses from 80 nm and up. The thickness of the film can be controlled by the fibril concentration and/or reaction time. The films contain anisotropic domains spanning several square centimeters. In addition, the films contains ordered assemblies of dyes that display emission of polarized light.

    National Category
    Organic Chemistry Biomaterials Science
    Identifiers
    urn:nbn:se:liu:diva-121019 (URN)
    Available from: 2015-09-02 Created: 2015-09-02 Last updated: 2015-09-02
    6. Protein nanowires with conductive properties
    Open this publication in new window or tab >>Protein nanowires with conductive properties
    Show others...
    2015 (English)In: Journal of Materials Chemistry C, ISSN 2050-7526, E-ISSN 2050-7534, Vol. 3, no 25, p. 6499-6504Article in journal (Refereed) Published
    Abstract [en]

    Herein we report on the investigation of self-assembled protein nanofibrils functionalized with metallic organic compounds. We have characterized the electronic behaviour of individual nanowires using conductive atomic force microscopy. In order to follow the self assembly process we have incorporated fluorescent molecules into the protein and used the energy transfer between the internalized dye and the metallic coating to probe the binding of the polyelectrolyte to the fibril.

    Place, publisher, year, edition, pages
    Royal Society of Chemistry, 2015
    National Category
    Biological Sciences
    Identifiers
    urn:nbn:se:liu:diva-120179 (URN)10.1039/c5tc00896d (DOI)000356529100010 ()
    Note

    Funding Agencies|Knut and Alice Wallenberg Foundation through a Wallenberg Scholar grant

    Available from: 2015-07-13 Created: 2015-07-13 Last updated: 2017-12-04
    7. PEDOT-S coated protein fibril microhelices
    Open this publication in new window or tab >>PEDOT-S coated protein fibril microhelices
    Show others...
    (English)Manuscript (preprint) (Other academic)
    Abstract [en]

    We show here the preparation and characterization of micrometer sized conductive helices. We utilize protein fibrils as structural templates to create chiral helices with either right or left handed helicity. The helices are coated with the conductive polymer alkoxysulfonate poly(ethylenedioxythiophene) (PEDOT-S) to create micrometer sized conductive helices. The coating acts as a stabilizer for the template structure, facilitates the preparation of solid state films and shows significant conductivity. The helices have been investigated using Circular Dichroism (CD) and scanning electron microscopy (SEM) and the conductivity have been measured for solid state films.

    National Category
    Biochemistry and Molecular Biology
    Identifiers
    urn:nbn:se:liu:diva-121020 (URN)
    Available from: 2015-09-02 Created: 2015-09-02 Last updated: 2015-09-02Bibliographically approved
  • 92.
    Bäcklund, Fredrik
    et al.
    Linköping University, Department of Physics, Chemistry and Biology, Biomolecular and Organic Electronics. Linköping University, Faculty of Science & Engineering.
    Elfwing, Anders
    Linköping University, Department of Physics, Chemistry and Biology, Biomolecular and Organic Electronics. Linköping University, Faculty of Science & Engineering.
    Ajjan, Fatimá Nadia
    Linköping University, Department of Physics, Chemistry and Biology, Biomolecular and Organic Electronics. Linköping University, Faculty of Science & Engineering.
    Babenko, Viktoria
    Department of Chemistry, Biological and Chemical Research Centre, University of Warsaw, Poland.
    Dzwolak, Wojciech
    Department of Chemistry, Biological and Chemical Research Centre, University of Warsaw, Poland.
    Solin, Niclas
    Linköping University, Department of Physics, Chemistry and Biology, Biomolecular and Organic Electronics. Linköping University, Faculty of Science & Engineering.
    Inganäs, Olle
    Linköping University, Department of Physics, Chemistry and Biology, Biomolecular and Organic Electronics. Linköping University, Faculty of Science & Engineering.
    PEDOT-S coated protein fibril microhelicesManuscript (preprint) (Other academic)
    Abstract [en]

    We show here the preparation and characterization of micrometer sized conductive helices. We utilize protein fibrils as structural templates to create chiral helices with either right or left handed helicity. The helices are coated with the conductive polymer alkoxysulfonate poly(ethylenedioxythiophene) (PEDOT-S) to create micrometer sized conductive helices. The coating acts as a stabilizer for the template structure, facilitates the preparation of solid state films and shows significant conductivity. The helices have been investigated using Circular Dichroism (CD) and scanning electron microscopy (SEM) and the conductivity have been measured for solid state films.

  • 93.
    Bäcklund, Fredrik
    et al.
    Linköping University, Department of Physics, Chemistry and Biology, Biomolecular and Organic Electronics. Linköping University, Faculty of Science & Engineering.
    Elfwing, Anders
    Linköping University, Department of Physics, Chemistry and Biology, Biomolecular and Organic Electronics. Linköping University, Faculty of Science & Engineering.
    Musumeci, Chiara
    Linköping University, Department of Physics, Chemistry and Biology, Biomolecular and Organic Electronics. Linköping University, Faculty of Science & Engineering.
    Ajjan, Fatima
    Linköping University, Department of Physics, Chemistry and Biology, Biomolecular and Organic Electronics. Linköping University, Faculty of Science & Engineering.
    Babenko, Viktoria
    University of Warsaw, Poland.
    Dzwolak, Wojciech
    University of Warsaw, Poland.
    Solin, Niclas
    Linköping University, Department of Physics, Chemistry and Biology, Biomolecular and Organic Electronics. Linköping University, Faculty of Science & Engineering.
    Inganäs, Olle
    Linköping University, Department of Physics, Chemistry and Biology, Biomolecular and Organic Electronics. Linköping University, Faculty of Science & Engineering.
    Conducting microhelices from self-assembly of protein fibrils2017In: Soft Matter, ISSN 1744-683X, E-ISSN 1744-6848, Vol. 13, no 25, p. 4412-4417Article in journal (Refereed)
    Abstract [en]

    Herein we utilize insulin to prepare amyloid based chiral heliceswith either right or left handed helicity. We demonstrate that thehelices can be utilized as structural templates for the conductingpolymer alkoxysulfonate poly(ethylenedioxythiophene) (PEDOT-S).The chirality of the helical assembly is transferred to PEDOT-S asdemonstrated by polarized optical microscopy (POM) and CircularDichroism (CD). Analysis of the helices by conductive atomic force(c-AFM) shows significant conductivity. In addition the morphologyof the template structure is stabilized by PEDOT-S. Theseconductive helical structures represent promising candidates in ourquest for THz resonators.

  • 94.
    Bäcklund, Fredrik G.
    et al.
    Linköping University, Department of Physics, Chemistry and Biology, Biomolecular and Organic Electronics. Linköping University, Faculty of Science & Engineering.
    Pallbo, Jon
    Linköping University, Department of Physics, Chemistry and Biology, Biomolecular and Organic Electronics. Linköping University, Faculty of Science & Engineering.
    Solin, Niclas
    Linköping University, Department of Physics, Chemistry and Biology, Biomolecular and Organic Electronics. Linköping University, Faculty of Science & Engineering.
    Controlling Amyloid Fibril Formation by Partial Stirring2016In: Biopolymers, ISSN 0006-3525, E-ISSN 1097-0282, Vol. 105, no 5, p. 249-259Article in journal (Refereed)
    Abstract [en]

    Many proteins undergoes self-assembly into fibrillar structures known as amyloid fibrils. During the self-assembly process related structures, known as spherulites, can be formed. Herein we report a facile method where the balance between amyloid fibrils and spherulites can be controlled by stirring of the reaction mixture during the initial stages of the self-assembly process. Moreover, we report how this methodology can be used to prepare non-covalently functionalized amyloid fibrils. By stirring the reaction mixture continuously or for a limited time during the lag phase the fibril length, and hence the propensity to form liquid crystalline phases, can be influenced. This phenomena is utilized by preparing films consisting of aligned protein fibrils incorporating the laser dye Nile red. The resulting films display polarized Nile red fluorescence.

  • 95.
    Bäcklund, Fredrik G.
    et al.
    Linköping University, Department of Physics, Chemistry and Biology, Biomolecular and Organic Electronics. Linköping University, Faculty of Science & Engineering.
    Solin, Niclas
    Linköping University, Department of Physics, Chemistry and Biology, Biomolecular and Organic Electronics. Linköping University, Faculty of Science & Engineering.
    Tuning the aqueous self-assembly process of insulin by a hydrophobic additive2015In: RSC ADVANCES, ISSN 2046-2069, Vol. 5, no 112, p. 92254-92262Article in journal (Refereed)
    Abstract [en]

    Biomolecular self-assembly is an efficient way of preparing soft-matter based materials. Herein we report a novel method, based on the use of insoluble additives in aqueous media, for influencing the self-assembly process. Due to their low solubility, the use of hydrophobic additives in aqueous media is problematic; however, by mixing the additive with the biomolecule in the solid state, prior to solvation, this problem can be circumvented. In the investigated self-assembly system, where bovine insulin self-assembles into spherical structures, the inclusion of the hydrophobic material α-sexithiophene (6T) results in significant changes in the self-assembly process. Under our reaction conditions, in the case of materials prepared from insulin-only the growth of spherulites typically stops at a diameter of 150μm. However, by adding 2 weight % of hydrophobic material, spherulite growth continues up to diameters in the mm-range. The spherulites incorporate 6T and are thus fluorescent. The method reported herein should be of interest to all scientists working in the field of self-assembly as the flexible materials preparation, based simply on co-grinding of commercially available materials, adds another option to influence the structure and properties of products formed by  self-assembly reactions.

  • 96.
    Bäcklund, Fredrik Gustaf
    et al.
    Linköping University, Department of Physics, Chemistry and Biology, Biomolecular and Organic Electronics. Linköping University, Faculty of Science & Engineering.
    Ajjan, Fátima Nadia
    Linköping University, Department of Physics, Chemistry and Biology, Biomolecular and Organic Electronics. Linköping University, Faculty of Science & Engineering.
    Solin, Niclas
    Linköping University, Department of Physics, Chemistry and Biology, Biomolecular and Organic Electronics. Linköping University, Faculty of Science & Engineering.
    Convection Induced Air-Water Interface Assembly of Amyloid FibrilsManuscript (preprint) (Other academic)
    Abstract [en]

    We report that hydrophobically modified amyloid fibrils form macroscopic films at the air-water interface. The hydrophobically modified fibrils are prepared in a two step process. First bovine insulin is ground with a hydrophobic compound. The resulting material is dissolved in acidic water and heated to induce assembly into fibrils incorporating the hydrophobic compounds. Upon dilution followed by asymmetric heating, resulting in convection flow, the fibrills form highly ordered films with thicknesses from 80 nm and up. The thickness of the film can be controlled by the fibril concentration and/or reaction time. The films contain anisotropic domains spanning several square centimeters. In addition, the films contains ordered assemblies of dyes that display emission of polarized light.

  • 97.
    Bäcklund, Fredrik
    et al.
    Linköping University, Department of Physics, Chemistry and Biology, Biomolecular and Organic Electronics. Linköping University, The Institute of Technology.
    Solin, Niclas
    Linköping University, Department of Physics, Chemistry and Biology, Biomolecular and Organic Electronics. Linköping University, The Institute of Technology.
    Development and Application of Methodology for Rapid Screening of Potential Amyloid Probes2014In: ACS COMBINATORIAL SCIENCE, ISSN 2156-8952, Vol. 16, no 12, p. 721-729Article in journal (Refereed)
    Abstract [en]

    Herein, we demonstrate that it is possible to rapidly screen hydrophobic fluorescent aromatic molecules with regards to their properties as amyloid probes. By grinding the hydrophobic molecule with the amyloidogenic protein insulin, we obtained a water-soluble composite material. When this material is dissolved and exposed to conditions promoting amyloid formation, the protein aggregates into amyloid fibrils incorporating the hydrophobic molecule. As a result, changes in the fluorescence spectra of the hydrophobic molecule can be correlated to the formation of amyloid fibrils, and the suitability of the hydrophobic molecular skeleton as an amyloid probe can thus be assessed. As a result, we discovered two new amyloid probes, of which one is the well-known laser dye DCM. The grinding method can also be used for rapid preparation of novel composite materials between dyes and proteins, which can be used in materials science applications such as organic electronics and photonics.

  • 98.
    Bäcklund, Fredrik
    et al.
    Linköping University, Department of Physics, Chemistry and Biology, Biomolecular and Organic Electronics. Linköping University, The Institute of Technology.
    Wigenius, Jens
    Chalmers, Sweden.
    Westerlund, Fredrik
    Chalmers, Sweden .
    Inganäs, Olle
    Linköping University, Department of Physics, Chemistry and Biology, Biomolecular and Organic Electronics. Linköping University, The Institute of Technology.
    Solin, Niclas
    Linköping University, Department of Physics, Chemistry and Biology, Biomolecular and Organic Electronics. Linköping University, The Institute of Technology.
    Amyloid fibrils as dispersing agents for oligothiophenes: control of photophysical properties through nanoscale templating and flow induced fibril alignment2014In: Journal of Materials Chemistry C, ISSN 2050-7526, E-ISSN 2050-7534, Vol. 2, no 37, p. 7811-7822Article in journal (Refereed)
    Abstract [en]

    Herein we report that protein fibrils formed from aggregated proteins, so called amyloid fibrils, serve as an excellent dispersing agent for hydrophobic oligothiophenes such as alpha-sexithiophene (6T). Furthermore, the protein fibrils are capable of orienting 6T along the fibril long axis, as demonstrated by flow-aligned linear dichroism spectroscopy and polarized fluorescence microscopy. The materials are prepared by solid state mixing of 6T with a protein capable of self-assembly. This results in a water soluble composite material that upon heating in aqueous acid undergoes self-assembly into protein fibrils non-covalently functionalized with 6T, with a typical diameter of 5-10 nm and lengths in the micrometre range. The resulting aqueous fibril dispersions are a readily available source of oligothiophenes that can be processed from aqueous solvent, and we demonstrate the fabrication of macroscopic structures consisting of aligned 6T functionalized protein fibrils. Due to the fibril induced ordering of 6T these structures exhibit polarized light emission.

  • 99.
    Cai, Tianqi
    et al.
    Chalmers.
    Zhou, Yi
    Linköping University, Department of Physics, Chemistry and Biology, Biomolecular and Organic Electronics. Linköping University, Faculty of Science & Engineering.
    Wang, Ergang
    Chalmers.
    Hellstrom, Stefan
    Chalmers.
    Zhang, Fengling
    Linköping University, Department of Physics, Chemistry and Biology, Biomolecular and Organic Electronics. Linköping University, The Institute of Technology.
    Xu, Shiai
    East China University of Science and Technology.
    Inganäs, Olle
    Linköping University, Department of Physics, Chemistry and Biology, Biomolecular and Organic Electronics. Linköping University, The Institute of Technology.
    Andersson, Mats R
    Chalmers.
    Low bandgap polymers synthesized by FeCol(3) oxidative polymerization2010In: SOLAR ENERGY MATERIALS AND SOLAR CELLS, ISSN 0927-0248, Vol. 94, no 7, p. 1275-1281Article in journal (Refereed)
    Abstract [en]

    Four low bandgap polymers, combining an alkyl thiophene donor with benzo[c][1,2,5]thiadiazole, 2,3-diphenylquinoxaline, 2,3-diphenylthieno[3,4-b]pyrazine and 6,7-diphenyl-[1,2,5]thiadiazolo[3,4-g] quinoxaline acceptors in a donor-acceptor-donor architecture, were synthesized via FeCl3 oxidative polymerization. The molecular weights of the polymers were improved by introducing o-dichlor-obenzene (ODCB) as the reaction solvent instead of the commonly used solvent, chloroform. The photophysical, electrochemical and photovoltaic properties of the resulting polymers were investigated and compared. The optical bandgaps of the polymers vary between 1.0 and 1.9 eV, which is promising for solar cells. The devices spin-coated from an ODCB solution of P1DB:[70]PCBM showed a power conversion efficiency of 1.08% with an open-circuit voltage of 0.91 V and a short-circuit current density of 3.36 mA cm(-2) under irradiation from an AM1.5G solar simulator (100 mW cm(-2)).

  • 100.
    Cai, Wanzhu
    et al.
    Linköping University, Department of Physics, Chemistry and Biology, Biomolecular and Organic Electronics. Linköping University, Faculty of Science & Engineering.
    Musumeci, Chiara
    Linköping University, Department of Physics, Chemistry and Biology, Biomolecular and Organic Electronics. Linköping University, Faculty of Science & Engineering.
    Ajjan, Fátima
    Linköping University, Department of Physics, Chemistry and Biology, Biomolecular and Organic Electronics. Linköping University, Faculty of Science & Engineering.
    Bao, Qinye
    Linköping University, Department of Physics, Chemistry and Biology, Surface Physics and Chemistry. Linköping University, Faculty of Science & Engineering. Key Laboratory of Polar Materials and Devices, Ministry of Education, East China Normal University, Shanghai, China.
    Zaifei, Zaifei
    Linköping University, Department of Physics, Chemistry and Biology, Biomolecular and Organic Electronics. Linköping University, Faculty of Science & Engineering.
    Tang, Zheng
    Linköping University, Department of Physics, Chemistry and Biology, Biomolecular and Organic Electronics. Linköping University, Faculty of Science & Engineering.
    Inganäs, Olle
    Linköping University, Department of Physics, Chemistry and Biology, Biomolecular and Organic Electronics. Linköping University, Faculty of Science & Engineering.
    Self-doped conjugated polyelectrolyte with tuneable work function for effective hole transport in polymer solar cells2016In: Journal of Materials Chemistry A, ISSN 2050-7488, Vol. 4, no 40, p. 15670-15675Article in journal (Refereed)
    Abstract [en]

    A water-soluble conjugated polyelectrolyte (CPE), PEDOT-S (poly(4-(2,3-dihydrothieno[3,4-b][1,4]dioxin-2-yl-methoxy)-1-butanesulfonic acid)), is demonstrated to be an excellent hole transport material in several polymer solar cells with different donor's HOMO (highest occupied molecular orbital). With a P3TI:PC71BM (poly[6,6′-bis(5′-bromo-3,4′-dioctyl-[2,2′-bithiophen]-5-yl)-1,1′-bis(2-hexyldecyl)-[3,3′-biindolinylidene]-2,2′-dione]:[6,6]-phenyl C71 butyric acid methyl ester) active layer, the device using PEDOT-S as a hole transport layer (HTL) outperforms the PEDOT:PSS-based devices due to an increased FF (fill factor). The devices' current density–voltage characteristics (JV) show that a PEDOT-S layer can operate well with a wide range of thicknesses as well, helped by its high conductivity and decent transparency. With UV-ozone treatment, the work function of the PEDOT-S can increase from 4.9 eV to 5.2 eV. In TQ1:PC71BM (poly[[2,3-bis(3-octyloxyphenyl)-5,8-quinoxalinediyl]-2,5-thiophenediyl]:PC71BM) devices, which have a deeper donor HOMO than P3TI, Voc is improved from 0.81 V to 0.92 V by 7 min UV-ozone treatment, along with a suppressed reverse injection current and increased Jsc (short-circuit current density) and FF. Topography study shows the excellent coating ability of PEDOT-S. Conductive atomic force microscopy (C-AFM) shows the out-of-plane current in PEDOT-S film is one thousand times higher than that in PEDOT:PSS PH 4083 film under the same electric field and has much more uniformly distributed current pathways.

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