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  • 1.
    Abdollahi Sani, Negar
    et al.
    Linköping University, Department of Science and Technology, Physics and Electronics. Linköping University, The Institute of Technology.
    Robertsson, Mats
    Linköping University, Department of Science and Technology. Linköping University, The Institute of Technology.
    Cooper, Philip
    De La Rue Plc, Overton, Hampshire, UK .
    Wang, Xin
    Acreo AB, Norrköping, Sweden.
    Svensson, Magnus
    Acreo AB, Norrköping, Sweden.
    Andersson Ersman, Peter
    Acreo AB, Norrköping, Sweden.
    Norberg, Petronella
    Acreo AB, Norrköping, Sweden.
    Nilsson, Marie
    Acreo AB, Norrköping, Sweden.
    Nilsson, David
    Acreo AB, Norrköping, Sweden.
    Liu, Xianjie
    Linköping University, Department of Physics, Chemistry and Biology, Surface Physics and Chemistry. Linköping University, The Institute of Technology.
    Hesselbom, Hjalmar
    Hesselbom Innovation and Development HB, Huddinge, Sweden .
    Akesso, Laurent
    De La Rue Plc, Overton, Hampshire, UK .
    Fahlman, Mats
    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, The Institute of Technology.
    Engquist, Isak
    Linköping University, Department of Science and Technology, Physics and Electronics. Linköping University, The Institute of Technology.
    Berggren, Magnus
    Linköping University, Department of Science and Technology, Physics and Electronics. Linköping University, The Institute of Technology. Acreo AB, Norrköping, Sweden.
    Gustafsson, Goran
    Acreo AB, Norrköping, Sweden.
    All-printed diode operating at 1.6 GHz2014In: Proceedings of the National Academy of Sciences of the United States of America, ISSN 0027-8424, E-ISSN 1091-6490, Vol. 111, no 33, p. 11943-11948Article in journal (Refereed)
    Abstract [en]

    Printed electronics are considered for wireless electronic tags and sensors within the future Internet-of-things (IoT) concept. As a consequence of the low charge carrier mobility of present printable organic and inorganic semiconductors, the operational frequency of printed rectifiers is not high enough to enable direct communication and powering between mobile phones and printed e-tags. Here, we report an all-printed diode operating up to 1.6 GHz. The device, based on two stacked layers of Si and NbSi2 particles, is manufactured on a flexible substrate at low temperature and in ambient atmosphere. The high charge carrier mobility of the Si microparticles allows device operation to occur in the charge injection-limited regime. The asymmetry of the oxide layers in the resulting device stack leads to rectification of tunneling current. Printed diodes were combined with antennas and electrochromic displays to form an all-printed e-tag. The harvested signal from a Global System for Mobile Communications mobile phone was used to update the display. Our findings demonstrate a new communication pathway for printed electronics within IoT applications.

  • 2.
    Ali Abbasi, Mazhar
    et al.
    Linköping University, Department of Science and Technology, Physics and Electronics. Linköping University, The Institute of Technology.
    Hussain Ibupoto, Zafar
    Linköping University, Department of Science and Technology, Physics and Electronics. 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.
    Nur, Omer
    Linköping University, Department of Science and Technology, Physics and Electronics. Linköping University, The Institute of Technology.
    Willander, Magnus
    Linköping University, Department of Science and Technology, Physics and Electronics. Linköping University, The Institute of Technology.
    The determination of valence band offset and the current transport properties of the p-NiO/n-ZnO heterojunction2013Manuscript (preprint) (Other academic)
    Abstract [en]

    The electron transport in the electronic devices has significant influence on the device performance, thus current transport properties determination is highly demanded for a particular device. Herein, we report the facile hydrothermal growth method based fabrication of p-NiO/n-ZnO heterojunction. The material characterization was performed by scanning electron microscopy, X-ray diffraction, transmission electron microscopy and X-ray photo electron spectroscopy. These techniques provided the good crystal quality, pure phase of p-NiO and n-ZnO nanostructures respectively. The measured valance band offset of composite nanostructure is 2.25 eV and conduction band offset was found to be 2.58 eV. The current transport properties of the fabricated p-n junction are governed by three different I-V regions. The impedance spectroscopy was used for the determination of the role of grain boundaries at the interface.

  • 3.
    Alnoor, Hatim
    et al.
    Linköping University, Department of Science and Technology. Linköping University, Faculty of Science & Engineering.
    Chey, Chan Oeurn
    Linköping University, Department of Science and Technology, Physics and Electronics. Linköping University, The Institute of Technology.
    Pozina, Galia
    Linköping University, Department of Physics, Chemistry and Biology, Thin Film Physics. 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.
    Khranovskyy, Volodymyr
    Linköping University, Department of Physics, Chemistry and Biology, Semiconductor Materials. Linköping University, Faculty of Science & Engineering.
    Willander, Magnus
    Linköping University, Department of Science and Technology, Physics and Electronics. Linköping University, Faculty of Science & Engineering.
    Nour, Omer
    Linköping University, Department of Science and Technology, Physics and Electronics. Linköping University, Faculty of Science & Engineering.
    Effect of precursor solutions stirring on deep level defects concentration and spatial distribution in low temperature aqueous chemical synthesis of zinc oxide nanorods2015In: AIP Advances, ISSN 2158-3226, E-ISSN 2158-3226, Vol. 5, no 8, article id 087180Article in journal (Refereed)
    Abstract [en]

    Hexagonal c-axis oriented zinc oxide (ZnO) nanorods (NRs) with 120-300 nm diameters are synthesized via the low temperature aqueous chemical route at 80 degrees C on silver-coated glass substrates. The influence of varying the precursor solutions stirring durations on the concentration and spatial distributions of deep level defects in ZnO NRs is investigated. Room temperature micro-photoluminesnce (mu-PL) spectra were collected for all samples. Cathodoluminescence (CL) spectra of the as-synthesized NRs reveal a significant change in the intensity ratio of the near band edge emission (NBE) to the deep-level emission (DLE) peaks with increasing stirring durations. This is attributed to the variation in the concentration of the oxygen-deficiency with increasing stirring durations as suggested from the X-ray photoelectron spectroscopy analysis. Spatially resolved CL spectra taken along individual NRs revealed that stirring the precursor solutions for relatively short duration (1-3 h), which likely induced high super saturation under thermodynamic equilibrium during the synthesis process, is observed to favor the formation of point defects moving towards the tip of the NRs. In contrary, stirring for longer duration (5-15 h) will induce low super saturation favoring the formation of point defects located at the bottom of the NRs. These findings demonstrate that it is possible to control the concentration and spatial distribution of deep level defects in ZnO NRs by varying the stirring durations of the precursor solutions.

  • 4.
    Alnoor, Hatim
    et al.
    Linköping University, Department of Science and Technology. Linköping University, Faculty of Science & Engineering.
    Pozina, Galia
    Linköping University, Department of Physics, Chemistry and Biology, Thin Film Physics. Linköping University, Faculty of Science & Engineering.
    Khranovskyy, Volodymyr
    Linköping University, Department of Physics, Chemistry and Biology, Semiconductor Materials. 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.
    Iandolo, Donata
    Linköping University, Department of Science and Technology, Physics and Electronics. Linköping University, Faculty of Science & Engineering.
    Willander, Magnus
    Linköping University, Department of Science and Technology, Physics and Electronics. Linköping University, Faculty of Science & Engineering.
    Nur, Omer
    Linköping University, Department of Science and Technology, Physics and Electronics. Linköping University, Faculty of Science & Engineering.
    Influence of ZnO seed layer precursor molar ratio on the density of interface defects in low temperature aqueous chemically synthesized ZnO nanorods/GaN light-emitting diodes2016In: Journal of Applied Physics, ISSN 0021-8979, E-ISSN 1089-7550, Vol. 119, no 16, p. 165702-Article in journal (Refereed)
    Abstract [en]

    Low temperature aqueous chemical synthesis (LT-ACS) of zinc oxide (ZnO) nanorods (NRs) has been attracting considerable research interest due to its great potential in the development of light-emitting diodes (LEDs). The influence of the molar ratio of the zinc acetate (ZnAc): KOH as a ZnO seed layer precursor on the density of interface defects and hence the presence of non-radiative recombination centers in LT-ACS of ZnO NRs/GaN LEDs has been systematically investigated. The material quality of the as-prepared seed layer as quantitatively deduced by the X-ray photoelectron spectroscopy is found to be influenced by the molar ratio. It is revealed by spatially resolved cathodoluminescence that the seed layer molar ratio plays a significant role in the formation and the density of defects at the n-ZnO NRs/p-GaN heterostructure interface. Consequently, LED devices processed using ZnO NRs synthesized with molar ratio of 1:5M exhibit stronger yellow emission (similar to 575 nm) compared to those based on 1:1 and 1:3M ratios as measured by the electroluminescence. Furthermore, seed layer molar ratio shows a quantitative dependence of the non-radiative defect densities as deduced from light-output current characteristics analysis. These results have implications on the development of high-efficiency ZnO-based LEDs and may also be helpful in understanding the effects of the ZnO seed layer on defect-related non-radiative recombination. Published by AIP Publishing.

  • 5.
    Alnoor, Hatim
    et al.
    Linköping University, Department of Science and Technology. Linköping University, Faculty of Science & Engineering.
    Savoyant, Adrien
    Aix Marseille University, France.
    Liu, Xianjie
    Linköping University, Department of Physics, Chemistry and Biology, Surface Physics and Chemistry. Linköping University, Faculty of Science & Engineering.
    Pozina, Galia
    Linköping University, Department of Physics, Chemistry and Biology, Thin Film Physics. Linköping University, Faculty of Science & Engineering.
    Willander, Magnus
    Linköping University, Department of Science and Technology, Physics and Electronics. Linköping University, Faculty of Science & Engineering.
    Nur, Omer
    Linköping University, Department of Science and Technology, Physics and Electronics. Linköping University, Faculty of Science & Engineering.
    An effective low-temperature solution synthesis of Co-doped [0001]-oriented ZnO nanorods2017In: Journal of Applied Physics, ISSN 0021-8979, E-ISSN 1089-7550, Vol. 121, no 21, article id 215102Article in journal (Refereed)
    Abstract [en]

    We demonstrate an efficient possibility to synthesize vertically aligned pure zinc oxide (ZnO) and Co-doped ZnO nanorods (NRs) using the low-temperature aqueous chemical synthesis (90 degrees C). Two different mixing methods of the synthesis solutions were investigated for the Co-doped samples. The synthesized samples were compared to pure ZnO NRs regarding the Co incorporation and crystal quality. Electron paramagnetic resonance (EPR) measurements confirmed the substitution of Co2+ inside the ZnO NRs, giving a highly anisotropic magnetic Co2+ signal. The substitution of Zn2+ by Co2+ was observed to be combined with a drastic reduction in the core-defect (CD) signal (g similar to 1.956) which is seen in pure ZnO NRs. As revealed by the cathodoluminescence (CL), the incorporation of Co causes a slight red-shift of the UV peak position combined with an enhancement in the intensity of the defect-related yellow-orange emission compared to pure ZnO NRs. Furthermore, the EPR and the CL measurements allow a possible model of the defect configuration in the samples. It is proposed that the as-synthesized pure ZnO NRs likely contain Zn interstitial (Zn-i(+)) as CDs and oxygen vacancy (V-O) or oxygen interstitial (O-i) as surface defects. As a result, Co was found to likely occupy the Zn-i(+), leading to the observed CDs reduction and hence enhancing the crystal quality. These results open the possibility of synthesis of highly crystalline quality ZnO NRs-based diluted magnetic semiconductors using the low-temperature aqueous chemical method. Published by AIP Publishing.

  • 6.
    Amin, Sidra
    et al.
    Lulea Univ Technol, Sweden; Shaheed Benazir Bhutto Univ, Pakistan.
    Tahira, Aneela
    Lulea Univ Technol, Sweden.
    Solangi, Amber
    Univ Sindh, Pakistan.
    Beni, Valerio
    Res Inst Sweden, Sweden.
    Morante, J. R.
    Catalonia Inst Energy Res IREC, Spain.
    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.
    Mazzaro, Raffaello
    Lulea Univ Technol, Sweden.
    Ibupoto, Zafar Hussain
    Lulea Univ Technol, Sweden; Univ Sindh, Pakistan.
    Vomiero, Alberto
    Lulea Univ Technol, Sweden.
    A practical non-enzymatic urea sensor based on NiCo2O4 nanoneedles2019In: RSC Advances, ISSN 2046-2069, E-ISSN 2046-2069, Vol. 9, no 25, p. 14443-14451Article in journal (Refereed)
    Abstract [en]

    We propose a new facile electrochemical sensing platform for determination of urea, based on a glassy carbon electrode (GCE) modified with nickel cobalt oxide (NiCo2O4) nanoneedles. These nanoneedles are used for the first time for highly sensitive determination of urea with the lowest detection limit (1 mu M) ever reported for the non-enzymatic approach. The nanoneedles were grown through a simple and low-temperature aqueous chemical method. We characterized the structural and morphological properties of the NiCo2O4 nanoneedles by TEM, SEM, XPS and XRD. The bimetallic nickel cobalt oxide exhibits nanoneedle morphology, which results from the self-assembly of nanoparticles. The NiCo2O4 nanoneedles are exclusively composed of Ni, Co, and O and exhibit a cubic crystalline phase. Cyclic voltammetry was used to study the enhanced electrochemical properties of a NiCo2O4 nanoneedle-modified GCE by overcoming the typical poor conductivity of bare NiO and Co3O4. The GCE-modified electrode is highly sensitive towards urea, with a linear response (R-2 = 0.99) over the concentration range 0.01-5 mM and with a detection limit of 1.0 mu M. The proposed non-enzymatic urea sensor is highly selective even in the presence of common interferents such as glucose, uric acid, and ascorbic acid. This new urea sensor has good viability for urea analysis in urine samples and can represent a significant advancement in the field, owing to the simple and cost-effective fabrication of electrodes, which can be used as a promising analytical tool for urea estimation.

  • 7.
    Atxabal, Ainhoa
    et al.
    CIC NanoGUNE, Spain.
    Braun, Slawomir
    Linköping University, Department of Physics, Chemistry and Biology, Surface Physics and Chemistry. Linköping University, Faculty of Science & Engineering.
    Arnold, Thorsten
    Technical University of Dresden, Germany.
    Sun, Xiangnan
    National Centre Nanosci and Technology, Peoples R China.
    Parui, Subir
    CIC NanoGUNE, Spain.
    Liu, Xianjie
    Linköping University, Department of Physics, Chemistry and Biology, Surface Physics and Chemistry. Linköping University, Faculty of Science & Engineering.
    Gozalvez, Cristian
    University of Basque Country UPV EHU, Spain.
    Llopis, Roger
    CIC NanoGUNE, Spain.
    Mateo-Alonso, Aurelio
    University of Basque Country UPV EHU, Spain; Basque Fdn Science, Spain.
    Casanova, Felix
    CIC NanoGUNE, Spain; Basque Fdn Science, Spain.
    Ortmann, Frank
    Technical University of Dresden, Germany.
    Fahlman, Mats
    Linköping University, Department of Physics, Chemistry and Biology, Surface Physics and Chemistry. Linköping University, Faculty of Science & Engineering.
    Hueso, Luis E.
    CIC NanoGUNE, Spain; Basque Fdn Science, Spain.
    Energy Level Alignment at Metal/Solution-Processed Organic Semiconductor Interfaces2017In: Advanced Materials, ISSN 0935-9648, E-ISSN 1521-4095, Vol. 29, no 19, article id 1606901Article in journal (Refereed)
    Abstract [en]

    Energy barriers between the metal Fermi energy and the molecular levels of organic semiconductor devoted to charge transport play a fundamental role in the performance of organic electronic devices. Typically, techniques such as electron photoemission spectroscopy, Kelvin probe measurements, and in-device hot-electron spectroscopy have been applied to study these interfacial energy barriers. However, so far there has not been any direct method available for the determination of energy barriers at metal interfaces with n-type polymeric semiconductors. This study measures and compares metal/solution-processed electron-transporting polymer interface energy barriers by in-device hot-electron spectroscopy and ultraviolet photoemission spectroscopy. It not only demonstrates in-device hot-electron spectroscopy as a direct and reliable technique for these studies but also brings it closer to technological applications by working ex situ under ambient conditions. Moreover, this study determines that the contamination layer coming from air exposure does not play any significant role on the energy barrier alignment for charge transport. The theoretical model developed for this work confirms all the experimental observations.

  • 8.
    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.
    Da, Peimei
    Univ Oxford, England.
    Li, Cheng
    Univ Bayreuth, Germany; Xiamen Univ, Peoples R China.
    Wang, Zhiping
    Univ Oxford, England.
    Yuan, Zhongcheng
    Linköping University, Department of Physics, Chemistry and Biology, Biomolecular and Organic Electronics. Linköping University, Faculty of Science & Engineering.
    Fu, Fan
    Empa-Swiss Federal Laboratories for Materials Science and Technology, Duebendorf, Switzerland.
    Kawecki, Maciej
    Empa, Switzerland; Univ Basel, Switzerland.
    Liu, Xianjie
    Linköping University, Department of Physics, Chemistry and Biology, Surface Physics and Chemistry. Linköping University, Faculty of Science & Engineering.
    Sakai, Nobuya
    Univ Oxford, England.
    Wang, Jacob Tse-Wei
    CSIRO Energy, Australia.
    Huettner, Sven
    Univ Bayreuth, Germany.
    Buecheler, Stephan
    Empa Swiss Fed Labs Mat Sci and Technol, Switzerland.
    Fahlman, Mats
    Linköping University, Department of Physics, Chemistry and Biology, Surface Physics and Chemistry. 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. Univ Oxford, England.
    Snaith, Henry J.
    Univ Oxford, England.
    Planar perovskite solar cells with long-term stability using ionic liquid additives2019In: Nature, ISSN 0028-0836, E-ISSN 1476-4687, Vol. 571, no 7764, p. 245-250Article in journal (Refereed)
    Abstract [en]

    Solar cells based on metal halide perovskites are one of the most promising photovoltaic technologies(1-4). Over the past few years, the long-term operational stability of such devices has been greatly improved by tuning the composition of the perovskites(5-9), optimizing the interfaces within the device structures(10-13), and using new encapsulation techniques(14,15). However, further improvements are required in order to deliver a longer-lasting technology. Ion migration in the perovskite active layer-especially under illumination and heat-is arguably the most difficult aspect to mitigate(16-18). Here we incorporate ionic liquids into the perovskite film and thence into positive-intrinsic-negative photovoltaic devices, increasing the device efficiency and markedly improving the long-term device stability. Specifically, we observe a degradation in performance of only around five per cent for the most stable encapsulated device under continuous simulated full-spectrum sunlight for more than 1,800 hours at 70 to 75 degrees Celsius, and estimate that the time required for the device to drop to eighty per cent of its peak performance is about 5,200 hours. Our demonstration of long-term operational, stable solar cells under intense conditions is a key step towards a reliable perovskite photovoltaic technology.

  • 9.
    Bao, Qinye
    et al.
    East China Normal Univ, Peoples R China.
    Braun, Slawomir
    Linköping University, Department of Physics, Chemistry and Biology, Surface Physics and Chemistry. Linköping University, Faculty of Science & Engineering.
    Wang, Chuan Fei
    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.
    Fahlman, Mats
    Linköping University, Department of Physics, Chemistry and Biology, Surface Physics and Chemistry. Linköping University, Faculty of Science & Engineering.
    Interfaces of (Ultra)thin Polymer Films in Organic Electronics2019In: Advanced Materials Interfaces, ISSN 2196-7350, Vol. 6, no 1, article id 1800897Article, review/survey (Refereed)
    Abstract [en]

    In this short review the energy level alignment of interfaces involving solution-processed conjugated polymer (and soluble small molecules) films is described. Some general material properties of conjugated polymers and their solution-processed films are introduced, and the basic physics involved in energy level alignment at their interfaces is then discussed. An overview of energy level bending in (ultra)thin conjugated polymer films (often referred to as "band bending") is given and the effects of ion-containing interlayers typically used in organic electronic devices such as polymer light emitting diodes and organic bulk heterojunction solar cells are explored. The review finishes by describing a few of the available computational models useful for predicting and/or modeling energy level alignment at interfaces of solution-processed polymer films and discusses their respective strengths and weaknesses.

    The full text will be freely available from 2019-09-30 13:12
  • 10.
    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.

  • 11.
    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.

  • 12.
    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.
    Fahlman, Mats
    Linköping University, Department of Physics, Chemistry and Biology, Surface Physics and Chemistry. Linköping University, The Institute of Technology.
    Oxygen- and Water-Based Degradation in [6,6]-Phenyl-C-61-Butyric Acid Methyl Ester (PCBM) Films2014In: ADVANCED ENERGY MATERIALS, ISSN 1614-6832, Vol. 4, no 6Article in journal (Refereed)
    Abstract [en]

    Effects of in situ oxygen/water exposure on the energetics of [6,6]-phenyl-C61-butyric acid methyl ester (PCBM) films are presented. For oxygen exposure, the work function is downshifted by ≈0.15 eV compared to the ideal integer charge transfer (ICT) curve for pristine PCBM, which is incompatible with significant introduction of electron trap states or p-doping. Water induces the highest occupied molecular orbital (HOMO) structure to undergo strong, irreversible modifications accompanied by a chemical interaction with PCBM.

  • 13.
    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

  • 14.
    Bao, Qinye
    et al.
    Linköping University, Department of Physics, Chemistry and Biology, Surface Physics and Chemistry. Linköping University, Faculty of Science & Engineering. East China Normal University, Peoples R China.
    Liu, Xianjie
    Linköping University, Department of Physics, Chemistry and Biology, Surface Physics and Chemistry. 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.
    Li, Yanqing
    Soochow University, Peoples R China.
    Tang, Jianxin
    Soochow University, Peoples R China.
    Duan, Chungang
    East China Normal University, Peoples R China.
    Fahlman, Mats
    Linköping University, Department of Physics, Chemistry and Biology, Surface Physics and Chemistry. Linköping University, Faculty of Science & Engineering.
    Energy Level Alignment of N-Doping Fullerenes and Fullerene Derivatives Using Air-Stable Dopant2017In: ACS Applied Materials and Interfaces, ISSN 1944-8244, E-ISSN 1944-8252, Vol. 9, no 40, p. 35476-35482Article in journal (Refereed)
    Abstract [en]

    Doping has been proved to be one of the powerful technologies to achieve significant improvement in the performance of organic electronic devices. Herein, we systematically map out the interface properties of solution-processed air-stable n-type (4(1,3-dimethyl-2,3-dihydro-1H-benzoimidazol-2-yl)phenyl) doping fullerenes and fullerene derivatives and establish a universal energy level alignment scheme for this class of n-doped system. At low doping levels at which the charge-transfer doping induces mainly bound charges, the energy level alignment of the n-doping organic semiconductor can be described by combining integer charger transfer-induced shifts with a so-called double-dipole step. At high doping levels, significant densities of free charges are generated and the charge flows between the organic film and the conducting electrodes equilibrating the Fermi level in a classic "depletion layer" scheme. Moreover, we demonstrate that the model holds for both n- and p-doping of pi-backbone molecules and polymers. With the results, we provide wide guidance for identifying the application of the current organic n-type doping technology in organic electronics.

  • 15.
    Bao, Qinye
    et al.
    Linköping University, Department of Physics, Chemistry and Biology, Surface Physics and Chemistry. Linköping University, Faculty of Science & Engineering. East China Normal Univ, Peoples R China; Soochow Univ, Peoples R China.
    Liu, Xianjie
    Linköping University, Department of Physics, Chemistry and Biology, Surface Physics and Chemistry. 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.
    Yang, Jianming
    East China Normal Univ, Peoples R China.
    Li, Yanqing
    Soochow Univ, Peoples R China.
    Tang, Jianxin
    Soochow Univ, Peoples R China.
    Duan, Chungang
    East China Normal Univ, Peoples R China.
    Fahlman, Mats
    Linköping University, Department of Physics, Chemistry and Biology, Surface Physics and Chemistry. Linköping University, Faculty of Science & Engineering.
    The Effect of Oxygen Uptake on Charge Injection Barriers in Conjugated Polymer Films2018In: ACS Applied Materials and Interfaces, ISSN 1944-8244, E-ISSN 1944-8252, Vol. 10, no 7, p. 6491-6497Article in journal (Refereed)
    Abstract [en]

    The energy offset between the electrode Fermi level and organic semiconductor transport levels is a key parameter controlling the charge injection barrier and hence efficiency of organic electronic devices. Here, we systematically explore the effect of in situ oxygen exposure on energetics in n-type conjugated polymer P(NDI2OD-T2) films. The analysis reveals that an interfacial potential step is introduced for a series of P(NDI2OD-T2) electrode contacts, causing a nearly constant downshift of the vacuum level, while the ionization energies versus vacuum level remain constant. These findings are attributed to the establishment of a so-called double-dipole step via motion of charged molecules and will modify the charge injection barriers at electrode contact. We further demonstrate that the same behavior occurs when oxygen interacts with p-type polymer TQ1 films, indicating it is possible to be a universal effect for organic semiconductOrs.

  • 16.
    Bao, Qinye
    et al.
    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, P.R. China.
    Liu, Xianjie
    Linköping University, Department of Physics, Chemistry and Biology, Surface Physics and Chemistry. 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.
    Yanqing, Li
    Institute of Functional Nano & Soft Materials (FUNSOM), Soochow University, Suzhou, P.R. China.
    Jianxin, Tang
    Institute of Functional Nano & Soft Materials (FUNSOM), Soochow University, Suzhou, P.R. China.
    Chungang, Duan
    Key Laboratory of Polar Materials and Devices, Ministry of Education, East China Normal University, Shanghai, P.R. China.
    Fahlman, Mats
    Linköping University, Department of Physics, Chemistry and Biology, Surface Physics and Chemistry. Linköping University, Faculty of Science & Engineering.
    Intermixing Effect on Electronic Structures of TQ1:PC71BM Bulk Heterojunction in Organic Photovoltaics2017In: Solar RRL, ISSN 2367-198X, Vol. 1, no 10, article id 1700142Article in journal (Refereed)
    Abstract [en]

    The interface energetics and intermixing effects of the donor/acceptor bulk heterojunction (BHJ) blends of poly[2,3‐bis‐(3‐octyloxyphenyl) quinoxaline‐5, 8‐dilyl‐alt‐thiophene‐2, 5‐diyl]: [6,6]‐phenyl C71butyric acid methyl ester (TQ1:PC71BM) have been investigated using ultraviolet photoemission spectroscopy (UPS) in combination with the integer charge transfer model. The TQ1:PC71BM represents the useful model system for BHJ organic photovoltaics featuring effective charge generation and transport. It finds out that the positive integer charge state of TQ1 are equal in energy to the negative integer charge state of PC71BM, leading to a negligible potential step at TQ1:PC71BM interface and thus the vacuum level alignment. It is observed that the TQ1 accumulates on the top of TQ1:PC71BM BHJ and UPS spectra as function of various blend ratios suggest that the TQ1 mixes finely with PC71BM with the little work function modification in a wide range. In addition, no significant influence of the long‐range Coulomb interactions or the intermolecular hybridization on the occupied electronic structures is present for the well‐intermixed TQ1:PC71BM BHJs. These findings provide deep insights into the properties of BHJ blends and are beneficial for the performance optimization in organic photovoltaics.

  • 17.
    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.

  • 18.
    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.

  • 19.
    Bao, Qinye
    et al.
    Linköping University, Department of Physics, Chemistry and Biology, Surface Physics and Chemistry. Linköping University, The Institute of Technology.
    Sandberg, Oskar
    Abo Akad University, Finland.
    Dagnelund, Daniel
    Linköping University, Department of Physics, Chemistry and Biology, Functional Electronic Materials. Linköping University, The Institute of Technology.
    Sanden, Simon
    Abo Akad University, Finland.
    Braun, Slawomir
    Linköping University, Department of Physics, Chemistry and Biology, Surface Physics and Chemistry. Linköping University, The Institute of Technology.
    Aarnio, Harri
    Abo Akad University, Finland.
    Liu, Xianjie
    Linköping University, Department of Physics, Chemistry and Biology, Surface Physics and Chemistry. Linköping University, The Institute of Technology.
    Chen, Weimin
    Linköping University, Department of Physics, Chemistry and Biology, Functional Electronic Materials. Linköping University, The Institute of Technology.
    Osterbacka, Ronald
    Abo Akad University, Finland.
    Fahlman, Mats
    Linköping University, Department of Physics, Chemistry and Biology, Surface Physics and Chemistry. Linköping University, The Institute of Technology.
    Trap-Assisted Recombination via Integer Charge Transfer States in Organic Bulk Heterojunction Photovoltaics2014In: Advanced Functional Materials, ISSN 1616-301X, E-ISSN 1616-3028, Vol. 24, no 40, p. 6309-6316Article in journal (Refereed)
    Abstract [en]

    Organic photovoltaics are under intense development and significant focus has been placed on tuning the donor ionization potential and acceptor electron affinity to optimize open circuit voltage. Here, it is shown that for a series of regioregular-poly(3-hexylthiophene): fullerene bulk heterojunction (BHJ) organic photovoltaic devices with pinned electrodes, integer charge transfer states present in the dark and created as a consequence of Fermi level equilibrium at BHJ have a profound effect on open circuit voltage. The integer charge transfer state formation causes vacuum level misalignment that yields a roughly constant effective donor ionization potential to acceptor electron affinity energy difference at the donor-acceptor interface, even though there is a large variation in electron affinity for the fullerene series. The large variation in open circuit voltage for the corresponding device series instead is found to be a consequence of trap-assisted recombination via integer charge transfer states. Based on the results, novel design rules for optimizing open circuit voltage and performance of organic bulk heterojunction solar cells are proposed.

  • 20.
    Ben Dkhil, Sadok
    et al.
    Aix Marseille University, France.
    Gaceur, Meriem
    Aix Marseille University, France.
    Karim Diallo, Abdou
    Aix Marseille University, France.
    Didane, Yahia
    Aix Marseille University, France.
    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.
    Margeat, Olivier
    Aix Marseille University, France.
    Ackermann, Jorg
    Aix Marseille University, France.
    Videlot-Ackermann, Christine
    Aix Marseille University, France.
    Reduction of Charge-Carrier Recombination at ZnO Polymer Blend Interfaces in PTB7-Based Bulk Heterojunction Solar Cells Using Regular Device Structure: Impact of ZnO Nanoparticle Size and Surfactant2017In: ACS Applied Materials and Interfaces, ISSN 1944-8244, E-ISSN 1944-8252, Vol. 9, no 20, p. 17257-17265Article in journal (Refereed)
    Abstract [en]

    Cathode interfacial layers, also called electron extraction layers (EELs), based on zinc oxide (ZnO) have been studied in polymer-blend solar cells toward optimization of the opto-electric properties. Bulk heterojunction solar cells based on poly( {4, 8-bis [(2- ethylhexyl) oxy]b enzo [1,2- b :4,5-b dithiophene-2,6-diyl}{3-fluoro-2-[(2-ethylhexyl)carbonyl]- thieno[3,4-b]thiophenediy1}) (PTB7) and [6,6]-phenyl-C71-butyric acid methyl ester (PC70BM) were realized in regular structure with all-solution-processed interlayers. A pair of commercially available surfactants, ethanolamine (EA) and ethylene glycol (EG), were used to modify the surface of ZnO nanoparticles (NPs) in alcohol-based dispersion. The influence of ZnO particle size was also studied by preparing dispersions of two NP diameters (6 versus 11 nm). Here, we show that performance improvement can be obtained in polymer solar cells via the use of solution-processed ZnO EELs based on surface-modified nanoparticles. By the optimizing of the ZnO dispersion, surfactant ratio, and the resulting morphology of EELs, PTB7/PC70BM solar cells with a power-conversion efficiency of 8.2% could be obtained using small sized EG-modified ZnO NPs that allow the clear enhancement of the performance of solution processed photovoltaic devices compared to state-of-the-art ZnO-based cathode layers.

  • 21.
    Boerrnert, Felix
    et al.
    Leibniz-Institut für Festkörper- und Werkstoffforschung Dresden e. V., Dresden, Germany.
    Boerrnert, Carina
    Max-Planck-Institut für Chemische Physik fester Stoffe, Dresden, Germany.
    Gorantla, Sandeep
    Leibniz-Institut für Festkörper- und Werkstoffforschung Dresden e. V., Dresden, Germany.
    Liu, Xianjie
    Linköping University, Department of Physics, Chemistry and Biology, Surface Physics and Chemistry. Linköping University, The Institute of Technology.
    Bachmatiuk, Alicja
    Leibniz-Institut für Festkörper- und Werkstoffforschung Dresden e. V., Dresden, Germany.
    Joswig, Jan-Ole
    Technische Universität Dresden, Dresden, Germany.
    Wagner, Frank P
    Max-Planck-Institut für Chemische Physik fester Stoffe, Dresden, Germany.
    Schaeffel, Franziska
    Leibniz-Institut für Festkörper- und Werkstoffforschung Dresden e. V., Dresden, Germany.
    Warner, Jamie H
    University of Oxford, Oxford, United Kingdom.
    Schoenfelder, Ronny
    Leibniz-Institut für Festkörper- und Werkstoffforschung Dresden e. V., Dresden, Germany.
    Rellinghaus, Bernd
    Leibniz-Institut für Festkörper- und Werkstoffforschung Dresden e. V., Dresden, Germany.
    Gemming, Thomas
    Leibniz-Institut für Festkörper- und Werkstoffforschung Dresden e. V., Dresden, Germany.
    Thomas, Juergen
    Leibniz-Institut für Festkörper- und Werkstoffforschung Dresden e. V., Dresden, Germany.
    Knupfer, Martin
    Leibniz-Institut für Festkörper- und Werkstoffforschung Dresden e. V., Dresden, Germany.
    Buechner, Bernd
    Leibniz-Institut für Festkörper- und Werkstoffforschung Dresden e. V., Dresden, Germany.
    Ruemmeli, Mark H
    Leibniz-Institut für Festkörper- und Werkstoffforschung Dresden e. V., Dresden, Germany and Technische Universität Dresden, Dresden, Germany.
    Single-wall-carbon-nanotube/single-carbon-chain molecular junctions2010In: Physical Review B. Condensed Matter and Materials Physics, ISSN 1098-0121, E-ISSN 1550-235X, Vol. 81, no 8, p. 085439-1-085439-5Article in journal (Refereed)
    Abstract [en]

    Stable junctions between a single carbon chain and two single-wall carbon nanotubes were produced via coalescence of functionalized fullerenes filled into a single-wall carbon nanotube and directly imaged by in situ transmission electron microscopy. First principles quantum chemical calculations support the observed stability of such molecular junctions. They also show that short carbon chains bound to other carbon structures are cumulenes and stable semiconductors due to Peierls-like distortion. Junctions like this can be regarded as archetypical building blocks for all-carbon molecular electronics.

  • 22.
    Braun, Slawomir
    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.
    Salaneck, William R
    Linköping University, Department of Physics, Chemistry and Biology, Surface Physics and Chemistry. 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.
    Fermi level equilibrium at donor-acceptor interfaces in multi-layered thin film stack of TTF and TCNQ2010In: Organic electronics, ISSN 1566-1199, E-ISSN 1878-5530, Vol. 11, no 2, p. 212-217Article in journal (Refereed)
    Abstract [en]

    Organic hetero-junctions in multi-layered thin film stacks comprising alternate layers of the molecular donor-tetrathiafulvalene (TTF) and the acceptor - tetracyanoquinodimethane (TCNQ), have been studied by ultraviolet photoelectron spectroscopy ( UPS). We show that the energy level alignment at the organic-organic interfaces in the stacks depends only upon the relative energy structure of the donor and acceptor molecules, in particular, the molecular integer charge transfer (ICT) states. The observed interfacial dipoles, across the multi-layered organic stacks, correspond to the difference in energy between the positive and the negative charge transfer states of the molecules constituting the interface. Consequently, Fermi level across the multi-layer system is pinned to those states, since the energetic conditions for the charge transfer across the interface are fulfilled. Hence the energy level alignment at donor - acceptor interfaces studied can be rationalized on the basis of integer charge transfer model (ICT-model). Moreover, we present the photoelectron spectra where 0.85 eV shift of the highest occupied molecular orbital (HOMO) of TTF during formation of TCNQ over-layer is directly observed. These studies contribute to the understanding of the nature of the offset between the frontier electronic levels of the donor and acceptor components which is of high importance in the engineering of efficient organic solar cells.

  • 23.
    Briones-Leon, Antonio
    et al.
    University of Vienna, Austria.
    Ayala, Paola
    University of Vienna, Austria.
    Liu, Xianjie
    Linköping University, Department of Physics, Chemistry and Biology, Surface Physics and Chemistry. Linköping University, The Institute of Technology.
    Yanagi, Kazuhiro
    Tokyo Metropolitan University, Japan.
    Weschke, Eugen
    Helmholtz Zentrum Berlin Mat and Energie, Germany.
    Eisterer, Michael
    Vienna University of Technology, Austria.
    Jiang, Hua
    Aalto University, Finland.
    Kataura, Hiromichi
    Nat Institute Adv Ind Science and Technology AIST, Japan.
    Pichler, Thomas
    University of Vienna, Austria.
    Shiozawa, Hidetsugu
    University of Vienna, Austria.
    Orbital and spin magnetic moments of transforming one-dimensional iron inside metallic and semiconducting carbon nanotubes2013In: Physical Review B. Condensed Matter and Materials Physics, ISSN 1098-0121, E-ISSN 1550-235X, Vol. 87, no 19Article in journal (Refereed)
    Abstract [en]

    The orbital and spin magnetic properties of iron inside metallic and semiconducting carbon nanotubes are studied by means of local x-ray magnetic circular dichroism (XMCD) and bulk superconducting quantum interference device (SQUID). The iron-nanotube hybrids are initially ferrocene filled single-walled carbon nanotubes (SWCNT) of different metallicities. We show that the ferrocene's molecular orbitals interact differently with the SWCNT of different metallicities with no significant XMCD response. At elevated temperatures the ferrocene molecules react with each other to form cementite nanoclusters. The XMCD at various magnetic fields reveal that the orbital and/or spin magnetic moments of the encapsulated iron are altered drastically as the transformation to the 1D clusters takes place. The orbital and spin magnetic moments are both found to be larger in filled semiconducting nanotubes than in the metallic sample. This could mean that the magnetic polarization of the encapsulated material depends on the metallicity of the tubes. From a comparison between the iron 3d magnetic moments and the bulk magnetism measured by SQUID, we conclude that the delocalized magnetisms dominate the magnetic properties of these 1D hybrid nanostructures.

  • 24.
    Briones-Leon, Antonio
    et al.
    University of Vienna, Austria .
    Liu, Xianjie
    Linköping University, Department of Physics, Chemistry and Biology, Surface Physics and Chemistry. Linköping University, The Institute of Technology.
    Ayala, Paola
    University of Vienna, Austria .
    Kataura, Hiromichi
    National Institute Adv Ind Science and Technology, Japan .
    Yanagi, Kazuhiro
    Tokyo Metropolitan University, Japan .
    Weschke, Eugen
    Helmholtz Zentrum Berlin Fr Mat and Energie, Germany .
    Pichler, Thomas
    University of Vienna, Austria .
    Shiozawa, Hidetsugu
    University of Vienna, Austria .
    Orbital and spin magnetic moments of ferrocene encapsulated in metallicity sorted single-walled carbon nanotubes2012In: Physica status solidi. B, Basic research, ISSN 0370-1972, E-ISSN 1521-3951, Vol. 249, no 12, p. 2424-2427Article in journal (Refereed)
    Abstract [en]

    The nature of the electronic and local magnetic properties of ferrocene (FeCp2) filled single-walled carbon nanotubes (SWCNT) has been investigated by X-ray absorption spectroscopy (XAS) and magnetic circular dichroism (XMCD). Metallic, semiconducting, and unsorted ferrocene-filled tubes have been studied in different conditions of temperature and magnetic field. XMCD signal becomes evident with the application of a magnetic field at low temperature. We find that the molecular states of ferrocene interact with SWCNT of different metallicities. A paramagnetic behavior of encapsulated ferrocene is observed from the magnetic field dependent XMCD measurements which is consistent with theoretical predictions.

  • 25.
    Brooke, Robert
    et al.
    Linköping University, Department of Science and Technology. Linköping University, Faculty of Science & Engineering.
    Franco Gonzalez, Felipe
    Linköping University, Department of Science and Technology, Physics and Electronics. Linköping University, Faculty of Science & Engineering.
    Wijeratne, Kosala
    Linköping University, Department of Science and Technology, Physics and Electronics. Linköping University, Faculty of Science & Engineering.
    Pavlopoulou, Eleni
    Univ Bordeaux, France.
    Galliani, Daniela
    Univ Milano Bicocca, Italy.
    Liu, Xianjie
    Linköping University, Department of Physics, Chemistry and Biology, Surface Physics and Chemistry. Linköping University, Faculty of Science & Engineering.
    Valiollahi Bisheh, Roudabeh
    Linköping University, Department of Science and Technology. Linköping University, Faculty of Science & Engineering.
    Zozoulenko, Igor
    Linköping University, Department of Science and Technology, Physics and Electronics. Linköping University, Faculty of Science & Engineering.
    Crispin, Xavier
    Linköping University, Department of Science and Technology, Physics and Electronics. Linköping University, Faculty of Science & Engineering.
    Vapor phase synthesized poly(3,4-ethylenedioxy-thiophene)-trifluoromethanesulfonate as a transparent conductor material2018In: Journal of Materials Chemistry A, ISSN 2050-7488, Vol. 6, no 43, p. 21304-21312Article in journal (Refereed)
    Abstract [en]

    Inorganic transparent conductive oxides have dominated the market as transparent electrodes due to their high conductivity and transparency. Here, we report the fabrication and optimization of the synthesis of poly(3,4-ethylenedioxythiophene) trifluoromethanesulfonate via vapor phase polymerization for the potential replacement of such inorganic materials. The parameters and conditions of the polymerization were investigated and an electrical conductivity of 3800 S cm(-1) and 4500 S cm(-1) after acid treatment were obtained while maintaining an absorbance similar to that of commercial indium tin oxide. This increase in electrical conductivity was rationalized experimentally and theoretically to an increase in the oxidation level and a higher order of crystallinity which does not disrupt the pi-pi stacking of PEDOT chains.

  • 26.
    Carlegrim, Elin
    et al.
    Linköping University, Department of Physics, Chemistry and Biology, Surface Physics and Chemistry. Linköping University, The Institute of Technology.
    Zhan, Yiqiang
    Linköping University, Department of Physics, Chemistry and Biology, Surface Physics and Chemistry. Linköping University, The Institute of Technology.
    Li, Fenghong
    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.
    Fahlman, Mats
    Linköping University, Department of Physics, Chemistry and Biology, Surface Physics and Chemistry. Linköping University, The Institute of Technology.
    Characterization of the Ni/V(TCNE)x interface for hybrid spintronics applications2010In: Organic electronics, ISSN 1566-1199, E-ISSN 1878-5530, Vol. 11, no 6, p. 1020-1024Article in journal (Refereed)
    Abstract [en]

    Vanadium tetracyanoethylene, V(TCNE)x, is an organic-based magnet with properties suitable for spintronics applications, e.g. spin valves. In this paper we propose a new hybrid organic spin valve design where V(TCNE)x is used as a spin-transporting and spin-filtering layer sandwiched between two ferromagnetic (FM) metal contacts, i.e. FM/V(TCNE)x/FM. As the spin injection and detection of such a device occurs at the interfaces the quality of those are of crucial importance. Therefore, the Ni/V(TCNE)x interface has been investigated by X-ray photoelectron spectroscopy (XPS) and near edge X-ray absorption spectroscopy (NEXAFS) as well as compared with XPS results from a model system, Ni/TCNE. Ni chemically interact with both the vinyl and cyano groups but there is no evidence for significant diffusion of Ni into the V(TCNE)x film. As the chemical interaction affects the spin injection and detection negatively by modifying the lowest unoccupied molecular orbital (LUMO) and destroying the magnetic ordering network at the surface, these results indicate that there is need for a buffer layer between V(TCNE)x and Ni, and in extension most likely between V(TCNE)x and any FM contact.

  • 27.
    Chey, Chan Oeurn
    et al.
    Linköping University, Department of Science and Technology, Physics and Electronics. Linköping University, The Institute of Technology.
    Alnoor, Hatim
    Linköping University, Department of Science and Technology, Physics and Electronics. 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.
    Abbasi, Mazhar Ali
    Linköping University, Department of Science and Technology, Physics and Electronics. Linköping University, The Institute of Technology.
    Nur, Omer
    Linköping University, Department of Science and Technology, Physics and Electronics. Linköping University, The Institute of Technology.
    Willander, Magnus
    Linköping University, Department of Science and Technology, Physics and Electronics. Linköping University, The Institute of Technology.
    ZnO nanorods based piezoresistive sensor synthesized by rapid mixing hydrothermal methodManuscript (preprint) (Other academic)
    Abstract [en]

    We have successfully synthesized well-aligned, shape controlled and uniform size distribution of ZnO nanorods by using a rapid mixing hydrothermal method. The scanning electron microscope (SEM), X-ray photoelectron spectroscopy (XPS) and X-ray diffraction (XRD) characterizations showed that the ZnO nanorods grow along the c-axis with hexagonal wurtzite ZnO structure. The room temperature cathodoluminescence (CL) investigation revealed that the ZnO nanorods have optical emissions in both the UV and visible ranges and the crystal quality of the ZnO nanorods can be improved by increasing the growth duration. The well-aligned and uniform ZnO nanorods were used to fabricate efficient piezoresistive sensor. The piezoresistive sensor has demonstrated a pressure sensitivity of 0.033 KPa-1 with a fast response and recovery times within 0.088 and 0.29 s, respectively. The piezoresistive sensor has potential applications in industrial, civil and transportation fields. Furthermore, the fabricated sensor can be utilized as a very useful human-friendly interactive electronic device for load sensing.

  • 28.
    Chey, Chan Oeurn
    et al.
    Linköping University, Department of Science and Technology, Physics and Electronics. 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.
    Alnoor, Hatim
    Linköping University, Department of Science and Technology, Physics and Electronics. Linköping University, The Institute of Technology.
    Nur, Omer
    Linköping University, Department of Science and Technology, Physics and Electronics. Linköping University, The Institute of Technology.
    Willander, Magnus
    Linköping University, Department of Science and Technology, Physics and Electronics. Linköping University, The Institute of Technology.
    Fast piezoresistive sensor and UV photodetector based on Mn-doped ZnO nanorods2014In: Physica Status Solidi. Rapid Research Letters, ISSN 1862-6254, E-ISSN 1862-6270, Vol. 9, no 1, p. 87-91Article in journal (Refereed)
    Abstract [en]

    A low cost hydrothermal synthesis method to synthesize Mn-doped ZnO nanorods (NRs) with controllable morphology and structure has been developed. Ammonia is used to tailor the ammonium hydroxide concentration, which provides a source of OH– for hydrolysis and precipitation during the growth instead of HMT. The morphological, chemical composition, structural, and electronic structure studies of the Mn-doped ZnO NRs show that the Mn-doped ZnO NRs have a hexagonal wurtzite ZnO structure along the c-axis and the Mn ions replace the Zn sites in the ZnO NRs matrix without any secondary phase of metallic manganese element and manganese oxides observed. The fabricated PEDOT:PSS/Zn0.85Mn0.15O Schottky diode based piezoresistive sensor and UV photodetector shows that the piezoresistive sensor has pressure sensitivity of 0.00617 kPa–1 for the pressure range from 1 kPa to 20 kP and 0.000180 kPa–1for the pressure range from 20 kPa to 320 kPa with relatively fast response time of 0.03 s and the UV photodetector has both relatively high responsivity and fast response time of 0.065 A/W and 2.75 s, respectively. The fabricated Schottky diode can be utilized as a very useful human-friendly interactive electronic device for mass/force sensor or UV photodetector in everyday living life. This developed device is very promising for small-size, low-cost and easy-to-customize application-specific requirements. (© 2014 WILEY-VCH Verlag GmbH &Co. KGaA, Weinheim)

  • 29.
    Chey, Chan Oeurn
    et al.
    Linköping University, Department of Science and Technology, Physics and Electronics. Linköping University, The Institute of Technology.
    Masood, Ansar
    Department of Materials Science, Royal Institute of Technology, Stockholm, Sweden.
    Riazanova, A.
    Department of Materials Science, Royal Institute of Technology, Stockholm, Sweden.
    Liu, Xianjie
    Linköping University, Department of Physics, Chemistry and Biology, Surface Physics and Chemistry. Linköping University, The Institute of Technology.
    Rao, K. V.
    Department of Materials Science, Royal Institute of Technology, Stockholm, Sweden.
    Nur, Omer
    Linköping University, Department of Science and Technology, Physics and Electronics. Linköping University, The Institute of Technology.
    Willander, Magnus
    Linköping University, Department of Science and Technology, Physics and Electronics. Linköping University, The Institute of Technology.
    Synthesis of Fe-Doped ZnO Nanorods by Rapid Mixing Hydrothermal Method and Its Application for High Performance UV Photodetector2014In: Journal of Nanomaterials, ISSN 1687-4110, E-ISSN 1687-4129, Vol. 2014, no 524530, p. 1-9Article in journal (Refereed)
    Abstract [en]

    We have successfully synthesized Fe-doped ZnO nanorods by a new and simple method in which the adopted approach is by using ammonia as a continuous source of OH for hydrolysis instead of hexamethylenetetramine (HMT). The energy dispersive X-ray (EDX) spectra revealed that the Fe peaks were presented in the grown Fe-doped ZnO nanorods samples and the X-ray photoelectron spectroscopy (XPS) results suggested that Fe3+ is incorporated into the ZnO lattice. Structural characterization indicated that the Fe-doped ZnO nanorods grow along the c-axis with a hexagonal wurtzite structure and have single crystalline nature without any secondary phases or clusters of FeO or Fe3O4 observed in the samples. The Fe-doped ZnO nanorods showed room temperature (300 K) ferromagnetic magnetization versus field (M-H) hysteresis and the magnetization increases from 2.5 μemu to 9.1 μemu for Zn0.99Fe0.01O and Zn0.95Fe0.05O, respectively. Moreover, the fabricated Au/Fe-doped ZnO Schottky diode based UV photodetector achieved 2.33 A/W of responsivity and 5 s of time response. Compared to other Au/ZnO nanorods Schottky devices, the presented responsivity is an improvement by a factor of 3.9.

  • 30.
    del Pozo, Freddy G.
    et al.
    Institute Ciencia Mat Barcelona ICMAB CSIC, Spain; Networking Research Centre Bioengn Biomat and Nanomed CIBER, Spain.
    Fabiano, Simone
    Linköping University, Department of Science and Technology, Physics and Electronics. Linköping University, Faculty of Science & Engineering.
    Pfattner, Raphael
    Institute Ciencia Mat Barcelona ICMAB CSIC, Spain; Networking Research Centre Bioengn Biomat and Nanomed CIBER, Spain.
    Georgakopoulos, Stamatis
    Institute Ciencia Mat Barcelona ICMAB CSIC, Spain; Networking Research Centre Bioengn Biomat and Nanomed CIBER, Spain.
    Galindo, Sergi
    Institute Ciencia Mat Barcelona ICMAB CSIC, Spain; Networking Research Centre Bioengn Biomat and Nanomed CIBER, Spain.
    Liu, Xianjie
    Linköping University, Department of Physics, Chemistry and Biology, Surface Physics and Chemistry. 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.
    Fahlman, Mats
    Linköping University, Department of Physics, Chemistry and Biology, Surface Physics and Chemistry. Linköping University, Faculty of Science & Engineering.
    Veciana, Jaume
    Institute Ciencia Mat Barcelona ICMAB CSIC, Spain; Networking Research Centre Bioengn Biomat and Nanomed CIBER, Spain.
    Rovira, Concepcio
    Institute Ciencia Mat Barcelona ICMAB CSIC, Spain; Networking Research Centre Bioengn Biomat and Nanomed CIBER, Spain.
    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.
    Mas-Torrent, Marta
    Institute Ciencia Mat Barcelona ICMAB CSIC, Spain; Networking Research Centre Bioengn Biomat and Nanomed CIBER, Spain.
    Single Crystal-Like Performance in Solution-Coated Thin-Film Organic Field-Effect Transistors2016In: Advanced Functional Materials, ISSN 1616-301X, E-ISSN 1616-3028, Vol. 26, no 14, p. 2379-2386Article in journal (Refereed)
    Abstract [en]

    In electronics, the field-effect transistor (FET) is a crucial cornerstone and successful integration of this semiconductor device into circuit applications requires stable and ideal electrical characteristics over a wide range of temperatures and environments. Solution processing, using printing or coating techniques, has been explored to manufacture organic field-effect transistors (OFET) on flexible carriers, enabling radically novel electronics applications. Ideal electrical characteristics, in organic materials, are typically only found in single crystals. Tiresome growth and manipulation of these hamper practical production of flexible OFETs circuits. To date, neither devices nor any circuits, based on solution-processed OFETs, has exhibited an ideal set of characteristics similar or better than todays FET technology based on amorphous silicon. Here, bar-assisted meniscus shearing of dibenzo-tetrathiafulvalene to coat-process self-organized crystalline organic semiconducting domains with high reproducibility is reported. Including these coatings as the channel in OFETs, electric field and temperature-independent charge carrier mobility and no bias stress effects are observed. Furthermore, record-high gain in OFET inverters and exceptional operational stability in both air and water are measured.

  • 31.
    Edberg, Jesper
    et al.
    Linköping University, Department of Science and Technology, Physics and Electronics. Linköping University, Faculty of Science & Engineering.
    Iandolo, Donata
    Linköping University, Department of Science and Technology, Physics and Electronics. Linköping University, Faculty of Science & Engineering.
    Brooke, Robert
    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.
    Musumeci, Chiara
    Linköping University, Department of Physics, Chemistry and Biology, Biomolecular and Organic Electronics. Linköping University, Faculty of Science & Engineering.
    Wenzel Andreasen, Jens
    Technical University of Denmark, Denmark.
    Simon, Daniel
    Linköping University, Department of Science and Technology, Physics and Electronics. Linköping University, Faculty of Science & Engineering.
    Evans, Drew
    University of South Australia, Australia.
    Engquist, Isak
    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.
    Patterning and Conductivity Modulation of Conductive Polymers by UV Light Exposure2016In: Advanced Functional Materials, ISSN 1616-301X, E-ISSN 1616-3028, Vol. 26, no 38, p. 6950-6960Article in journal (Refereed)
    Abstract [en]

    A novel patterning technique of conductive polymers produced by vapor phase polymerization is demonstrated. The method involves exposing an oxidant film to UV light which changes the local chemical environment of the oxidant and subsequently the polymerization kinetics. This procedure is used to control the conductivity in the conjugated polymer poly(3,4-ethylenedioxythiophene): tosylate by more than six orders of magnitude in addition to producing high-resolution patterns and optical gradients. The mechanism behind the modulation in the polymerization kinetics by UV light irradiation as well as the properties of the resulting polymer are investigated.

  • 32.
    Elfwing, Anders
    et al.
    Linköping University, Department of Physics, Chemistry and Biology, Biomolecular and Organic Electronics. Linköping University, Faculty of Science & Engineering.
    Cai, Wanzhu
    Linköping University, Department of Physics, Chemistry and Biology, Biomolecular and Organic Electronics. Linköping University, Faculty of Science & Engineering.
    Ouyang, Liangqi
    Linköping University, Department of Physics, Chemistry and Biology, Biomolecular and Organic 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.
    Xia, Yuxin
    Linköping University, Department of Physics, Chemistry and Biology, Biomolecular and Organic Electronics. Linköping University, Faculty of Science & Engineering.
    Tang, Zheng
    Tech Univ Dresden, Germany.
    Inganäs, Olle
    Linköping University, Department of Physics, Chemistry and Biology, Biomolecular and Organic Electronics. Linköping University, Faculty of Science & Engineering.
    DNA Based Hybrid Material for Interface Engineering in Polymer Solar Cells2018In: ACS Applied Materials and Interfaces, ISSN 1944-8244, E-ISSN 1944-8252, Vol. 10, no 11, p. 9579-9586Article in journal (Refereed)
    Abstract [en]

    A new solution processable electron transport material (ETM) is introduced for use in photovoltaic devices, which consists of a metallic conjugated polyelectrolyte, poly(4-(2,3-dihydrothieno[3,4-b]-[1,4]dioxin-2-yl-methoxy)-1-butanesulfonic acid (PEDOT-S), and surfactant-functionalized deoxyribonucleic acid (DNA) (named DNA:CTMA:PEDOT-S). This ETM is demonstrated to effectively work for bulk-heterojunction organic photovoltaic devices (OPV) based on different electron acceptor materials. The fill factor, the open circuit voltage, and the overall power conversion efficiency of the solar cells with a DNA:CTMA:PEDOT-S modified cathode are comparable to those of devices with a traditional lithium fluoride/aluminum cathode. The new electron transport layer has high optical transmittance, desired work function and selective electron transport. A dipole effect induced by the use of the surfactant cetyltrimethylammonium chloride (CTMA) is responsible for lowering the electrode work function. The DNA:CTMA complex works as an optical absorption dilutor, while PEDOT-S provides the conducting pathway for electron transport, and allows thicker layer to be used, enabling printing. This materials design opens a new pathway to harness and optimize the electronic and optical properties of printable interface materials.

  • 33.
    Elhadi Adam, Rania
    et al.
    Linköping University, Department of Science and Technology. Linköping University, Faculty of Science & Engineering.
    Pirhashemi, Mahsa
    Linköping University, Department of Science and Technology, Physics and Electronics. Linköping University, Faculty of Science & Engineering. University of Mohaghegh Ardabili, Ardabil, Iran.
    Elhag, Sami
    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.
    Habibi-Yangjeh, Aziz
    University of Mohaghegh Ardabili, Ardabil, Iran.
    Willander, Magnus
    Linköping University, Department of Science and Technology, Physics and Electronics. Linköping University, Faculty of Science & Engineering.
    Nur, Omer
    Linköping University, Department of Science and Technology, Physics and Electronics. Linköping University, Faculty of Science & Engineering.
    ZnO/Ag/Ag2WO4 photo-electrodes with plasmonic behavior for enhanced photoelectrochemical water oxidation2019In: RSC Advances, ISSN 2046-2069, E-ISSN 2046-2069, Vol. 9, no 15, p. 8271-8279Article in journal (Refereed)
    Abstract [en]

    Ag-based compounds are excellent co-catalyst that can enhance harvesting visible light and increase photo-generated charge carrier separation owing to its surface plasmon resonance (SPR) effect in photoelectrochemical (PEC) applications. However, the PEC performance of a ZnO/Ag/Ag2WO4 heterostructure with SPR behavior has not been fully studied so far. Here we report the preparation of a ZnO/Ag/Ag2WO4 photo-electrode with SPR behavior by a low temperature hydrothermal chemical growth method followed by a successive ionic layer adsorption and reaction (SILAR) method. The properties of the prepared samples were investigated by different characterization techniques, which confirm that Ag/Ag2WO4 was deposited on the ZnO NRs. The Ag2WO4/Ag/ZnO photo-electrode showed an enhancement in PEC performance compared to bare ZnO NRs. The observed enhancement is attributed to the red shift of the optical absorption spectrum of the Ag2WO4/Ag/ZnO to the visible region (>400 nm) and to the SPR effect of surface metallic silver (Ag0) particles from the Ag/Ag2WO4 that could generate electron–hole pairs under illumination of low energy visible sun light. Finally, we proposed the PEC mechanism of the Ag2WO4/Ag/ZnO photo-electrode with an energy band structure and possible electron–hole separation and transportation in the ZnO/Ag/Ag2WO4 heterostructure with SPR effect for water oxidation. ER

  • 34.
    Elhag, Sami
    et al.
    Linköping University, Department of Science and Technology. Linköping University, The Institute of Technology.
    Ibupoto, Zafar Hussain
    Linköping University, Department of Science and Technology, Physics and Electronics. 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.
    Nur, Omer
    Linköping University, Department of Science and Technology, Physics and Electronics. Linköping University, The Institute of Technology.
    Willander, Magnus
    Linköping University, Department of Science and Technology, Physics and Electronics. Linköping University, The Institute of Technology.
    Dopamine wide range detection sensor based on modified Co3O4 nanowires electrode2014In: Sensors and actuators. B, Chemical, ISSN 0925-4005, E-ISSN 1873-3077, Vol. 203, p. 543-549Article in journal (Refereed)
    Abstract [en]

    Ultra-thin cobalt oxide (Co3O4) nanowires grown on gold coated glass substrates by the hydrothermal chemical deposition and have been used as a wide range dopamine potentiometric sensor. An anionic surfactant ( sodium dodecylbenzenesulfonate) was used to achieve assisted growth procedure. Moreover, a polymeric membrane containing polyvinyl chloride as plasticized polymer, p-cyclodextrin as ionophore, and potassium tetrakis (4-chlorophenyl) borate as ionic additive were immobilized on the Co3O4 nanostructures through electrostatic adsorption method. X-ray diffraction, X-ray photoelectron spectroscopy, and scanning electron microscopy were used to characterize the electrodes while ultraviolet-visible absorption was used to investigate the band gap of the Co3O4 nanostructures. The structural characterization showed a cubic crystalline, pure phase, and nanowires morphology of the Co3O4. However, the morphology is altered when the surfactant concentration has been changed. The Co3O4 chemical modified electrodes were used in potentiometric measurements for dopamine in a 10(-2) M acetic acid/sodium acetate solution having a pH of 5.45. For dopamine range from 10(-9) M to 10(-2) M, the potential response of the sensor electrode was linear with a slope of 52 mV/decade. The wide range and high sensitivity of the modified Co3O4 nanowires based sensor for dopamine is attributed to the defects on the metal oxide that is dictated by the used surfactant along with the high surface area-to-volume ratio.

  • 35.
    Elhag, Sami
    et al.
    Linköping University, Department of Science and Technology. Linköping University, Faculty of Science & Engineering.
    Khun, Kimleang
    Linköping University, Department of Science and Technology, Physics and Electronics. Linköping University, The Institute of Technology.
    Khranovskyy, Volodymyr
    Linköping University, Department of Physics, Chemistry and Biology, Semiconductor Materials. 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.
    Willander, Magnus
    Linköping University, Department of Science and Technology, Physics and Electronics. Linköping University, Faculty of Science & Engineering.
    Nour, Omer
    Linköping University, Department of Science and Technology, Physics and Electronics. Linköping University, Faculty of Science & Engineering.
    Efficient Donor Impurities in ZnO Nanorods by Polyethylene Glycol for Enhanced Optical and Glutamate Sensing Properties2016In: Sensors, ISSN 1424-8220, E-ISSN 1424-8220, Vol. 16, no 2Article in journal (Refereed)
    Abstract [en]

    In this paper, we show that the possibility of using polyethylene glycol (EG) as a hydrogen source and it is used to assist the hydrothermal synthesis of ZnO nanorods (ZNRs). EG doping in ZNRs has been found to significantly improve their optical and chemical sensing characteristics toward glutamate. The EG was found to have no role on the structural properties of the ZNRs. However, the x-ray photoelectron spectroscopy (XPS) suggests that the EG could induce donor impurities effect in ZnO. Photoluminescence (PL) and UV-Vis. spectra demonstrated this doping effect. Mott-Schottky analysis at the ZNRs/electrolyte interface was used to investigate the charge density for the doped ZNRs and showed comparable dependence on the used amount of EG. Moreover, the doped ZNRs were used in potentiometric measurements for glutamate for a range from 10(-6) M to 10(-3) M and the potential response of the sensor electrode was linear with a slope of 91.15 mV/decade. The wide range and high sensitivity of the modified ZNRs based glutamate biosensor is attributed to the doping effect on the ZNRs that is dictated by the EG along with the high surface area-to-volume ratio. The findings in the present study suggest new avenues to control the growth of n-ZnO nanostructures and enhance the performance of their sensing devices.

  • 36.
    Elhag, Sami
    et al.
    Linköping University, Department of Science and Technology. Linköping University, Faculty of Science & Engineering.
    Tordera, Daniel
    Linköping University, Department of Science and Technology. Linköping University, Faculty of Science & Engineering.
    Deydier, T
    Department of Material Engineering, University of Toulon, FR-83041 Toulon, France .
    Lu, Jun
    Linköping University, Department of Physics, Chemistry and Biology, Thin Film Physics. Linköping University, Faculty of Science & Engineering.
    LiU, Xianjie
    Linköping University, Department of Physics, Chemistry and Biology, Thin Film Physics. Linköping University, Faculty of Science & Engineering.
    Khranovskyy, Volodymyr
    Linköping University, Faculty of Science & Engineering. Linköping University, Department of Physics, Chemistry and Biology, Thin Film Physics.
    Hultman, Lars
    Linköping University, Department of Physics, Chemistry and Biology, Thin Film Physics. Linköping University, Faculty of Science & Engineering.
    Willander, Magnus
    Linköping University, Department of Science and Technology, Physics and Electronics. Linköping University, Faculty of Science & Engineering.
    Jonsson, Magnus
    Linköping University, Department of Science and Technology, Physics and Electronics. Linköping University, Faculty of Science & Engineering.
    Nur, Omer
    Linköping University, Department of Science and Technology, Physics and Electronics. Linköping University, Faculty of Science & Engineering.
    Low-temperature growth of polyethylene glycol-doped BiZn2VO6 nanocompounds with enhanced photoelectrochemical properties2017In: Journal of Materials Chemistry A, ISSN 2050-7488, Vol. 5, no 3, p. 1112-1119Article in journal (Refereed)
    Abstract [en]

    We demonstrate scalable, low-cost and low-temperature (<100 °C) aqueous chemical growth of bismuth–zinc vanadate (BiZn2VO6) nanocompounds by BiVO4 growth on ZnO nanobelts (NBs). The nanocompounds were further doped with polyethylene glycol (PEG) to tune the electronic structure of the materials, as a means to lower the charge carrier recombination rate. The chemical composition, morphology, and detailed nanostructure of the BiZn2VO6 nanocompounds were characterized. They exhibit rice-like morphology, are highly dense on the substrate and possess a good crystalline quality. Photoelectrochemical characterization in 0.1 M lithium perchlorate in carbonate propylene shows that BiZn2VO6 nanocompounds are highly suitable as anodes for solar-driven photoelectrochemical applications, providing significantly better performance than with only ZnO NBs. This performance could be attributed to the heterogeneous catalysis effect at nanocompound and ZnO NB interfaces, which have enhanced the electron transfer process on the electrode surface. Furthermore, the charge collection efficiency could be significantly improved through PEG doping of nanocompounds. The photocurrent density of PEG-doped BiZn2VO6 nanocompounds reached values of 2 mA cm−2 at 1.23 V (vs. Ag/AgCl), over 60% larger than that of undoped BiZn2VO6 nanocompounds. Photoluminescence emission experiments confirmed that PEG plays a crucial role in lowering the charge carrier recombination rate. The presented BiZn2VO6 nanocompounds are shown to provide highly competitive performance compared with other state-of-the art photoelectrodes.

  • 37.
    Fabiano, Simone
    et al.
    Linköping University, Department of Science and Technology, Physics and Electronics. 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.
    Liu, Xianjie
    Linköping University, Department of Physics, Chemistry and Biology, Surface Physics and Chemistry. Linköping University, The Institute of Technology.
    Weverberghs, Eric
    University of Mons-UMONS, Belgium.
    Gerbaux, Pascal
    University of Mons-UMONS, Belgium.
    Fahlman, Mats
    Linköping University, Department of Physics, Chemistry and Biology, Surface Physics and Chemistry. Linköping University, The Institute of Technology.
    Berggren, Magnus
    Linköping University, Department of Science and Technology, Physics and Electronics. Linköping University, The Institute of Technology.
    Crispin, Xavier
    Linköping University, Department of Science and Technology, Physics and Electronics. Linköping University, The Institute of Technology.
    Poly(ethylene imine) impurities induce n-doping reaction in organic (semi)conductors2014In: Advanced Materials, ISSN 0935-9648, E-ISSN 1521-4095, Vol. 26, no 34, p. 6000-6006Article in journal (Refereed)
    Abstract [en]

    Volatile impurities contained in polyethyleneimine (PEI), and identified as ethyleneimine dimers and trimers, are reported. These N-based molecules show a strong reducing character, as demonstrated by the change in electrical conductivity of organic (semi) conductors exposed to the PEI vapor. The results prove that electron transfer rather than a dipole effect at the electrode interface is the origin of the work-function modification by the PEI-based layers.

  • 38.
    Fredj, Donia
    et al.
    Univ Sfax, Tunisia.
    Pourcin, Florent
    Aix Marseille Univ, France.
    Alkarsifi, Riva
    Aix Marseille Univ, France.
    Kilinc, Volkan
    Aix Marseille Univ, France.
    Liu, Xianjie
    Linköping University, Department of Physics, Chemistry and Biology, Surface Physics and Chemistry. Linköping University, Faculty of Science & Engineering.
    Ben Dkhil, Sadok
    Aix Marseille Univ, France.
    Boudjada, Nassira Chniba
    CNRS, France.
    Fahlman, Mats
    Linköping University, Department of Physics, Chemistry and Biology, Surface Physics and Chemistry. Linköping University, Faculty of Science & Engineering.
    Videlot-Ackermann, Christine
    Aix Marseille Univ, France.
    Margeat, Olivier
    Aix Marseille Univ, France.
    Ackermann, Joerg
    Aix Marseille Univ, France.
    Boujelbene, Mohamed
    Univ Sfax, Tunisia.
    Fabrication and Characterization of Hybrid Organic-Inorganic Electron Extraction Layers for Polymer Solar Cells toward Improved Processing Robustness and Air Stability2018In: ACS Applied Materials and Interfaces, ISSN 1944-8244, E-ISSN 1944-8252, Vol. 10, no 20, p. 17309-17317Article in journal (Refereed)
    Abstract [en]

    Organic-inorganic hybrid materials composed of bismuth and diaminopyridine are studied as novel materials for electron extraction layers in polymer solar cells using regular device structures. The hybrid materials are solution processed on top of two different low band gap polymers (PTB7 or PTB7-Th) as donor materials mixed with fullerene PC70BM as the acceptor. The intercalation of the hybrid layer between the photoactive layer and the aluminum cathode leads to solar cells with a power conversion efficiency of 7.8% because of significant improvements in all photovoltaic parameters, that is, short-circuit current density, fill factor, and open-circuit voltage, similar to the reference devices using ZnO as the interfacial layer. However when using thick layers of such hybrid materials for electron extraction, only small losses in photocurrent density are observed in contrast to the reference material ZnO of pronounced losses because of optical spacer effects. Importantly, these hybrid electron extraction layers also strongly improve the device stability in air compared with solar cells processed with ZnO interlayers. Both results underline the high potential of this new class of hybrid materials as electron extraction materials toward robust processing of air stable organic solar cells.

  • 39.
    Gaceur, Meriem
    et al.
    Aix Marseille University, France.
    Ben Dkhil, Sadok
    Aix Marseille University, France.
    Duche, David
    Aix Marseille University, France.
    Bencheikh, Fatima
    Aix Marseille University, France.
    Simon, Jean-Jacques
    Aix Marseille University, France.
    Escoubas, Ludovic
    Aix Marseille University, France.
    Mansour, Mahdi
    University of Jaume 1, Spain.
    Guerrero, Antonio
    University of Jaume 1, Spain.
    Garcia-Belmonte, Germa
    University of Jaume 1, Spain.
    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.
    Dachraoui, Walid
    Aix Marseille University, France.
    Karim Diallo, Abdou
    Aix Marseille University, France.
    Videlot-Ackermann, Christine
    Aix Marseille University, France.
    Margeat, Olivier
    Aix Marseille University, France.
    Ackermann, Joerg
    Aix Marseille University, France.
    Ligand-Free Synthesis of Aluminum-Doped Zinc Oxide Nanocrystals and their Use as Optical Spacers in Color-Tuned Highly Efficient Organic Solar Cells2016In: Advanced Functional Materials, ISSN 1616-301X, E-ISSN 1616-3028, Vol. 26, no 2, p. 243-253Article in journal (Refereed)
    Abstract [en]

    The color of polymer solar cells using an opaque electrode is given by the reflected light, which depends on the composition and thickness of each layer of the device. Metal-oxide-based optical spacers are intensively studied in polymer solar cells aiming to optimize the light absorption. However, the low conductivity of materials such as ZnO and TiO2 limits the thickness of such optical spacers to tenths of nanometers. A novel synthesis route of cluster-free Al-doped ZnO (AZO) nanocrystals (NCs) is presented for solution processing of highly conductive layers without the need of temperature annealing, including thick optical spacers on top of polymer blends. The processing of 80 nm thick optical spacers based on AZO nanocrystal solutions on top of 200 nm thick polymer blend layer is demonstrated leading to improved photocurrent density of 17% compared to solar cells using standard active layers of 90 nm in combination with thin ZnO-based optical spacers. These AZO NCs also open new opportunities for the processing of high-efficiency color tuned solar cells. For the first time, it is shown that applying solution-processed thick optical spacer with polymer blends of different thicknesses can process solar cells of similar efficiency over 7% but of different colors.

  • 40.
    Guo, Xuewen
    et al.
    East China Normal Univ, Peoples R China.
    Zhang, Yuexing
    Soochow Univ, Peoples R China.
    Liu, Xianjie
    Linköping University, Department of Physics, Chemistry and Biology, Surface Physics and Chemistry. 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.
    Wang, Zhiquan
    East China Normal Univ, Peoples R China.
    Li, Bo
    East China Normal Univ, Peoples R China.
    Li, Yanqing
    Soochow Univ, Peoples R China.
    Duan, Chungang
    East China Normal Univ, Peoples R China; Shanxi Univ, Peoples R China.
    Fahlman, Mats
    Linköping University, Department of Physics, Chemistry and Biology, Surface Physics and Chemistry. Linköping University, Faculty of Science & Engineering.
    Tang, Jianxin
    East China Normal Univ, Peoples R China.
    Fang, Junfeng
    Chinese Acad Sci, Peoples R China.
    Bao, Qinye
    Linköping University, Department of Physics, Chemistry and Biology, Surface Physics and Chemistry. Linköping University, Faculty of Science & Engineering. East China Normal Univ, Peoples R China.
    Novel small-molecule zwitterionic electrolyte with ultralow work function as cathode modifier for inverted polymer solar cells2018In: Organic electronics, ISSN 1566-1199, E-ISSN 1878-5530, Vol. 59, p. 15-20Article in journal (Refereed)
    Abstract [en]

    Interfacial compatibility between the electrode and organic semiconductor plays a critical role in controlling the charge transport and hence efficiency of organic solar cell. Here, we introduce a novel small-molecule zwitterionic electrolyte (S1) combined with ZnO as electron transporting interlayer employed for the inverted PTB7:PC71BM bulk heterojunction solar cell. The resulting device with the S1/ZnO stacked interlayer achieves a high PCE of 8.59%, obtaining a 16.2% improvement over the control device performance of 7.4% without the S1 attributed to the significant increased short-circuit current density and fill factor. The interfacial properties are investigated. It is found that the S1/ZnO interlayer possess an ultralow work function of 3.6 eV, which originates from the interfacial double dipole step induced by the zwitterionic side chain electrostatic realignment at interface. The S1/ZnO interlayer exhibits the excellent charge extraction ability, suppresses the charge recombination loss and decreases the series resistance at the active layer/electrode contact.

  • 41.
    Henry, Anne
    et al.
    Linköping University, Department of Physics, Chemistry and Biology, Thin Film Physics. Linköping University, The Institute of Technology.
    Leone, Stefano
    Linköping University, Department of Physics, Chemistry and Biology, Semiconductor Materials. 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.
    Ul-Hassan, Jawad
    Linköping University, Department of Physics, Chemistry and Biology, Semiconductor Materials. Linköping University, The Institute of Technology.
    Kordina, Olle
    Linköping University, Department of Physics, Chemistry and Biology, Semiconductor Materials. Linköping University, The Institute of Technology.
    Bergman, J. Peder
    Linköping University, Department of Physics, Chemistry and Biology, Semiconductor Materials. Linköping University, Faculty of Science & Engineering.
    Janzén, Erik
    Linköping University, Department of Physics, Chemistry and Biology, Semiconductor Materials. Linköping University, The Institute of Technology.
    Epitaxial growth on on-axis substrates2012In: Silicon Carbide Epitaxy / [ed] Francesco La Via, Kerala, India: Research Signpost, 2012, p. 97-119Chapter in book (Refereed)
    Abstract [en]

    SiC epitaxial growth using the Chemical Vapour Deposition (CVD) technique on nominally on-axis substrate is presented. Both standard and chloride-based chemistry have been used with the aim to obtain high quality layers suitable for device fabrication. Both homoepitaxy (4H on 4H) and heteroepitaxy (3C on hexag onal substrate) are addressed.

  • 42.
    Hussain Ibupoto, Zafar
    et al.
    Linköping University, Department of Science and Technology, Physics and Electronics. Linköping University, The Institute of Technology.
    Jamal, N
    Linköping University, Department of Science and Technology, Physics and Electronics. Linköping University, The Institute of Technology.
    Khun, Kimleang
    Linköping University, Department of Science and Technology, Physics and Electronics. 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.
    Willander, Magnus
    Linköping University, Department of Science and Technology, Physics and Electronics. Linköping University, The Institute of Technology.
    A potentiometric immunosensor based on silver nanoparticles decorated ZnO nanotubes, for the selective detection of d-dimer2013In: Sensors and actuators. B, Chemical, ISSN 0925-4005, E-ISSN 1873-3077, Vol. 182, p. 104-111Article in journal (Refereed)
    Abstract [en]

    In this study, a new, simple, fast and highly sensitive potentiometric immunosensor for the selective detection of d-dimer is developed using silver nanoparticles decorated ZnO nanotubes. The d-dimer is a biomarker and found at high levels in the human body when it suffers from deep vein thrombosis (DVT) disorders. ZnO nanotubes were obtained by the chemical etching of nanorods using a hydrothermal method. The silver nanoparticles were deposited on the ZnO nanotubes using an electrodepositing technique. The structure and the composition characterization was measured by scanning electron microscopy (SEM), X-ray diffraction (XRD), transmission electron microscopy (TEM) and X-ray photoelectron spectroscopy (XPS) techniques respectively. The ZnO nanorods are perpendicular to the substrate with uniform distribution. The etching of the nanorods into nanotubes is almost complete and the nanotubes are fully covered with silver nanoparticles. The mouse anti human d-dimer antibody was immobilized on the silver nanoparticles decorated ZnO nanotubes for the selective detection of d-dimer. The potentiometric immunosensor has shown a highly sensitive and linear response for the wide range of 1.00 x 10(-5)-1.00 x 10(0) mu g/ml d-dimer concentrations prepared in the phosphate buffer solution of pH 7.4. The presented d-dimer biosensor exhibited a detection limit of 1.00 x 10(-6) mu g/ml. The antibody immobilized immunosensor presents a fast response time of less than 5 s with acceptable selectivity, reproducibility and storage stability. The observed performance of the developed immunosensor demonstrates the high usability for the selective detection of the d-dimer from clinical and real samples.

  • 43.
    Hussain Ibupoto, Zafar
    et al.
    Linköping University, Department of Science and Technology. Linköping University, The Institute of Technology.
    Khun, K
    Linköping University, Department of Science and Technology. 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.
    Willander, Magnus
    Linköping University, Department of Science and Technology, Physics and Electronics. Linköping University, The Institute of Technology.
    Low temperature synthesis of seed mediated CuO bundle of nanowires, their structural characterisation and cholesterol detection2013In: Materials science & engineering. C, biomimetic materials, sensors and systems, ISSN 0928-4931, E-ISSN 1873-0191, Vol. 33, no 7, p. 3889-3898Article in journal (Refereed)
    Abstract [en]

    In this study, we have successfully synthesised CuO bundle of nanowires using simple, cheap and low temperature hydrothermal growth method. The growth parameters such as precursor concentration and time for duration of growth were optimised. The field emission scanning electron microscopy (FESEM) has demonstrated that the CuO bundles of nanowires are highly dense, uniform and perpendicularly oriented to the substrate. The high resolution transmission electron microscopy (HRTEM) has demonstrated that the CuO nanostructures consist of bundle of nanowires and their growth pattern is along the [010] direction. The X-ray diffraction (XRD) technique described that CuO bundle of nanowires possess the monoclinic crystal phase. The surface and chemical composition analyses were carried out with X-ray photoelectron spectroscopy (XPS) technique and the obtained results suggested the pure crystal state of CuO nanostructures. In addition, the CuO nanowires were used for the cholesterol sensing application by immobilising the cholesterol oxidase through electrostatic attraction. The infrared reflection absorption spectroscopy study has also revealed that CuO nanostructures are consisting of only Cu-O bonding and has also shown the possible interaction of cholesterol oxidase with the sharp edge surface of CuO bundle of nanowires. The proposed cholesterol sensor has demonstrated the wide range of detection of cholesterol with good sensitivity of 33.88 +/- 0.96 mV/decade. Moreover, the CuO bundle of nanowires based sensor electrode has revealed good repeatability, reproducibility, stability, selectivity and a fast response time of less than 10 s. The cholesterol sensor based on the immobilised cholesterol oxidase has good potential applicability for the determination of cholesterol from the human serum and other biological samples.

  • 44.
    Hussain Ibupoto, Zafar
    et al.
    Linköping University, Department of Science and Technology. Linköping University, The Institute of Technology.
    Khun, K
    Linköping University, Department of Science and Technology. Linköping University, The Institute of Technology.
    Lu, Jun
    Linköping University, Department of Physics, Chemistry and Biology, Thin Film Physics. 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.
    AlSalhi, M S.
    King Saud University, Saudi Arabia .
    Atif, M
    King Saud University, Saudi Arabia .
    Ansari, Anees A:
    King Saud University, Saudi Arabia .
    Willander, Magnus
    Linköping University, Department of Science and Technology, Physics and Electronics. Linköping University, The Institute of Technology.
    Well aligned ZnO nanorods growth on the gold coated glass substrate by aqueous chemical growth method using seed layer of Fe3O4 and Co3O4 nanoparticles2013In: Journal of Crystal Growth, ISSN 0022-0248, E-ISSN 1873-5002, Vol. 368, p. 39-46Article in journal (Refereed)
    Abstract [en]

    In this study, Fe3O4 and Co3O4 nanoparticles were prepared by co-precipitation method and sol-gel method respectively. The synthesised nanoparticles were characterised by X-ray diffraction [XRD] and Raman spectroscopy techniques. The obtained results have shown the nanocrystalline phase of obtained Fe3O4 and Co3O4 nanoparticles. Furthermore, the Fe3O4 and Co3O4 nanoparticles were used as seed layer for the fabrication of well-aligned ZnO nanorods on the gold coated glass substrate by aqueous chemical growth method. Scanning electron microscopy (SEM), high resolution transmission electron microscopy [HRTEM], as well as XRD and energy dispersive X-ray techniques were used for the structural characterisation of synthesised ZnO nanorods. This study has explored highly dense, uniform, well-aligned growth pattern along 0001 direction and good crystal quality of the prepared ZnO nanorods. ZnO nanorods are only composed of Zn and O atoms. Moreover, X-ray photoelectron spectroscopy was used for the chemical analysis of fabricated ZnO nanorods. In addition, the structural characterisation and the chemical composition study and the optical investigation were carried out for the fabricated ZnO nanorods and the photoluminescence [PL] spectrum have shown strong ultraviolet (UV) peak at 381 nm for Fe3O4 nanoparticles seeded ZnO nanorods and the PL spectrum for ZnO nanorods grown with the seed layer of Co3O4 nanoparticles has shown a UV peak at 382 nm. The green emission and orange/red peaks were also observed for ZnO nanorods grown with both the seed layers. This study has indicated the fabrication of well aligned ZnO nanorods using the one inorganic nanomaterial on other inorganic nanomaterial due to their similar chemistry.

  • 45.
    Hussain, Mushtaque
    et al.
    Linköping University, Department of Science and Technology, Physics and Electronics. Linköping University, The Institute of Technology.
    Ibupoto, Zafar Hussain
    Linköping University, Department of Science and Technology, Physics and Electronics. Linköping University, The Institute of Technology.
    Abbasi, Mazhar Ali
    Linköping University, Department of Science and Technology, Physics and Electronics. 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.
    Nur, Omer
    Linköping University, Department of Science and Technology, Physics and Electronics. Linköping University, The Institute of Technology.
    Willander, Magnus
    Linköping University, Department of Science and Technology, Physics and Electronics. Linköping University, The Institute of Technology.
    Synthesis of Three Dimensional Nickel Cobalt Oxide Nanoneedles on Nickel Foam, Their Characterization and Glucose Sensing Application2014In: Sensors, ISSN 1424-8220, E-ISSN 1424-8220, Vol. 14, no 3, p. 5415-5425Article in journal (Refereed)
    Abstract [en]

    In the present work, NiCo2O4 nanostructures are fabricated in three dimensions (3D) on nickel foam by the hydrothermal method. The nanomaterial was characterized by scanning electron microscopy (SEM), X-ray diffraction (XRD) and X-ray photoelectron spectroscopy (XPS). The nanostructures exhibit nanoneedle-like morphology grown in 3D with good crystalline quality. The nanomaterial is composed of nickel, cobalt and oxygen atoms. By using the favorable porosity of the nanomaterial and the substrate itself, a sensitive glucose sensor is proposed by immobilizing glucose oxidase. The presented glucose sensor has shown linear response over a wide range of glucose concentrations from 0.005 mM to 15 mM with a sensitivity of 91.34 mV/decade and a fast response time of less than 10 s. The NiCo2O4 nanostructures-based glucose sensor has shown excellent reproducibility, repeatability and stability. The sensor showed negligible response to the normal concentrations of common interferents with glucose sensing, including uric acid, dopamine and ascorbic acid. All these favorable advantages of the fabricated glucose sensor suggest that it may have high potential for the determination of glucose in biological samples, food and other related areas.

  • 46.
    Iandolo, Donata
    et al.
    Linköping University, Department of Science and Technology, Physics and Electronics. Linköping University, Faculty of Science & Engineering.
    Ravichandran, Akhilandeshwari
    School of Chemical and Biomedical Engineering, Nanyang Technological University, Singapore.
    Liu, Xianjie
    Linköping University, Department of Physics, Chemistry and Biology, Surface Physics and Chemistry. Linköping University, Faculty of Science & Engineering.
    Wen, Feng
    School of Chemical and Biomedical Engineering, Nanyang Technological University, Singapore.
    Chan, Jerry K Y
    Department of Obstetrics and Gynaecology, Yong Loo Lin School of Medicine, National University of Singapore, Singapore.
    Berggren, Magnus
    Linköping University, Department of Science and Technology, Physics and Electronics. Linköping University, Faculty of Science & Engineering.
    Teoh, Swee-Hin
    School of Chemical and Biomedical Engineering, Nanyang Technological University, Singapore.
    Simon, Daniel T
    Linköping University, Department of Science and Technology, Physics and Electronics. Linköping University, Faculty of Science & Engineering.
    Development and Characterization of Organic Electronic Scaffolds for Bone Tissue Engineering2016In: Advanced Healthcare Materials, ISSN 2192-2640, E-ISSN 2192-2659, Vol. 5, no 12, p. 1505-1512Article in journal (Refereed)
    Abstract [en]

    Bones have been shown to exhibit piezoelectric properties, generating electrical potential upon mechanical deformation and responding to electrical stimulation with the generation of mechanical stress. Thus, the effects of electrical stimulation on bone tissue engineering have been extensively studied. However, in bone regeneration applications, only few studies have focused on the use of electroactive 3D biodegradable scaffolds at the interphase with stem cells. Here a method is described to combine the bone regeneration capabilities of 3D-printed macroporous medical grade polycaprolactone (PCL) scaffolds with the electrical and electrochemical capabilities of the conducting polymer poly(3,4-ethylenedioxythiophene) (PEDOT). PCL scaffolds have been highly effective in vivo as bone regeneration grafts, and PEDOT is a leading material in the field of organic bioelectronics, due to its stability, conformability, and biocompatibility. A protocol is reported for scaffolds functionalization with PEDOT, using vapor-phase polymerization, resulting in a conformal conducting layer. Scaffolds' porosity and mechanical stability, important for in vivo bone regeneration applications, are retained. Human fetal mesenchymal stem cells proliferation is assessed on the functionalized scaffolds, showing the cytocompatibility of the polymeric coating. Altogether, these results show the feasibility of the proposed approach to obtain electroactive scaffolds for electrical stimulation of stem cells for regenerative medicine.

  • 47.
    Ibupoto, Zafar Hussain
    et al.
    Linköping University, Department of Science and Technology, Physics and Electronics. Linköping University, The Institute of Technology.
    Abbasi, Mazhar Ali
    Linköping University, Department of Science and Technology, Physics and Electronics. 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.
    AlSalhi, M. S.
    King Saud University, Riyadh, Saudi Arabia .
    Willander, Magnus
    Linköping University, Department of Science and Technology, Physics and Electronics. Linköping University, The Institute of Technology.
    The Synthesis of NiO/TiO2 Heterostructures and Their Valence Band Offset Determination2014In: Journal of Nanomaterials, ISSN 1687-4110, E-ISSN 1687-4129, no 928658Article in journal (Refereed)
    Abstract [en]

    In this work, a heterojunction based on p-type NiO/n-type TiO2 nanostructures has been prepared on the fluorine doped tin oxide (FTO) glass substrate by hydrothermal method. Scanning electron microscopy (SEM) and X-Ray diffraction techniques were used for the morphological and crystalline arrays characterization. The X-ray photoelectron spectroscopy was employed to determine the valence-band offset (VBO) of the NiO/TiO2 heterojunction prepared on FTO glass substrate. The core levels of Ni 2p and Ti 2p were utilized to align the valence-band offset of p-type NiO/n-type TiO2 heterojunction. The valence band offset was found to be similar to 0.41 eV and the conduction band was calculated about similar to 0.91 eV. The ratio of conduction band offset and the valence-band offset was found to be 2.21.

  • 48.
    Ibupoto, Zafar Hussain
    et al.
    Linköping University, Department of Science and Technology, Physics and Electronics. Linköping University, The Institute of Technology.
    Khun, Kimleang
    Linköping University, Department of Science and Technology, Physics and Electronics. Linköping University, The Institute of Technology.
    Beni, Valerio
    Linköping University, Department of Physics, Chemistry and Biology, Biosensors and Bioelectronics. 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.
    Willander, Magnus
    Linköping University, Department of Science and Technology, Physics and Electronics. Linköping University, The Institute of Technology.
    Synthesis of Novel CuO Nanosheets and Their Non-Enzymatic Glucose Sensing Applications2013In: Sensors, ISSN 1424-8220, E-ISSN 1424-8220, Vol. 13, no 6, p. 7926-7938Article in journal (Refereed)
    Abstract [en]

    Abstract: In this study, we have developed a sensitive and selective glucose sensor using novel CuO nanosheets which were grown on a gold coated glass substrate by a low temperature growth method. X-ray differaction (XRD) and scanning electron microscopy (SEM) techniques were used for the structural characterization of CuO nanostructures. CuO nanosheets are highly dense, uniform, and exhibited good crystalline array structure. X-ray photoelectron spectroscopy (XPS) technique was applied for the study of chemical composition of CuO nanosheets and the obtained information demonstrated pure phase CuO nanosheets. The novel CuO nanosheets were employed for the development of a sensitive and selective non-enzymatic glucose sensor. The measured sensitivity and a correlation coefficient are in order 5.20 × 102 µA/mMcm2 and 0.998, respectively. The proposed sensor is associated with several advantages such as low cost, simplicity, high stability, reproducibility and selectivity for the quick detection of glucose.

  • 49.
    Ibupoto, Zafar Hussain
    et al.
    Linköping University, Department of Science and Technology, Physics and Electronics. Linköping University, The Institute of Technology.
    Khun, Kimleang
    Linköping University, Department of Science and Technology, Physics and Electronics. 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.
    Willander, Magnus
    Linköping University, Department of Science and Technology, Physics and Electronics. Linköping University, The Institute of Technology.
    A Potentiometric Biosensor for the Detection of Notch 3 Using Functionalized ZnO Nanorods2014In: Journal of Nanoscience and Nanotechnology, ISSN 1533-4880, E-ISSN 1533-4899, Vol. 14, no 9, p. 6704-6710Article in journal (Refereed)
    Abstract [en]

    The notch signalling plays a vital and radical role for the activity of cellular proliferation, differentiation and apoptosis. In this study, for the first time a particular biosensor is developed for the detection of notch 3. ZnO nanorods were fabricated on the gold coated glass substrate by hydrothermal method and afterwards were decorated with the gold nanoparticles by electrodepositing technique. Scanning electron microscopy (SEM) has shown the perpendicular to the substrate growth pattern of ZnO nanorods. X-ray diffraction (XRD) studies showed the c-axis oriented growth direction with wurtzite crystal structure of ZnO nanorods. X-ray Photoelectron Spectroscopy (XPS) and energy dispersive X-ray (EDX) techniques have shown the presence of Zn, O and Au atoms in the prepared functional material. Furthermore, the anti-notch 3 was physically adsorbed on the gold nanoparticles functionalized ZnO nanorods. The developed potentiometric immunosensor has shown response to the wide range of notch 3 molecules. The detected range included 1.00 x 10(-5)-1.50 x 10(0) mu g/mL with a sensitivity of 23.15 +/- 0.31 mV/decade. The analytical parameters including reproducibility, stability, and selectivity were also investigated and the observed results indicate the acceptable performance of the notch 3 biosensor. Moreover, the proposed notch 3 biosensor exhibited a fast response time of 10 s.

  • 50.
    Ibupoto, Zafar Hussain
    et al.
    Division of Material Science, Department of Engineering Sciences and Mathematics, Luleå University of Technology, Luleå, Sweden; Dr. M.A Kazi Institute of Chemistry University of Sindh Jamshoro, Sindh, Pakistan.
    Tahira, Aneela
    Division of Material Science, Department of Engineering Sciences and Mathematics, Luleå University of Technology, Luleå, Sweden.
    Tang, PengYi
    Catalan Institute of Nanoscience and Nanotechnology (ICN2), CSIC and BIST, Campus UAB, Bellaterra, Barcelona, Catalonia, Spain; Catalonia Institute for Energy Research (IREC), Jardins de les Dones de Negre 1, Sant Adrià del Besòs, Barcelona, Catalonia, Spain.
    Liu, Xianjie
    Linköping University, Department of Physics, Chemistry and Biology, Surface Physics and Chemistry. Linköping University, Faculty of Science & Engineering.
    Morante, Joan Ramon
    Catalonia Institute for Energy Research (IREC), Jardins de les Dones de Negre 1, Sant Adrià del Besòs, Barcelona, Catalonia, Spain.
    Fahlman, Mats
    Linköping University, Department of Physics, Chemistry and Biology, Surface Physics and Chemistry. Linköping University, Faculty of Science & Engineering.
    Arbiol, Jordi
    Catalan Institute of Nanoscience and Nanotechnology (ICN2), CSIC and BIST, Campus UAB, Bellaterra, Barcelona, Catalonia, Spain; ICREA, Pg. Lluís Companys 23, Barcelona, Catalonia, Spain.
    Vagin, Mikhail
    Linköping University, Department of Science and Technology, Laboratory of Organic Electronics. Linköping University, Faculty of Science & Engineering.
    Vomiero, Alberto
    Division of Material Science, Department of Engineering Sciences and Mathematics, Luleå University of Technology, Luleå, Sweden.
    MoSx@NiO Composite Nanostructures: An Advanced Nonprecious Catalyst for Hydrogen Evolution Reaction in Alkaline Media2019In: Advanced Functional Materials, ISSN 1616-301X, E-ISSN 1616-3028, Vol. 29, no 7, article id 1807562Article in journal (Refereed)
    Abstract [en]

    The design of the earth-abundant, nonprecious, efficient, and stable electrocatalysts for efficient hydrogen evolution reaction (HER) in alkaline media is a hot research topic in the field of renewable energies. A heterostructured system composed of MoSx deposited on NiO nanostructures (MoSx@NiO) as a robust catalyst for water splitting is proposed here. NiO nanosponges are applied as cocatalyst for MoS2 in alkaline media. Both NiO and MoS2@NiO composites are prepared by a hydrothermal method. The NiO nanostructures exhibit sponge-like morphology and are completely covered by the sheet-like MoS2. The NiO and MoS2 exhibit cubic and hexagonal phases, respectively. In the MoSx@NiO composite, the HER experiment in 1 m KOH electrolyte results in a low overpotential (406 mV) to produce 10 mA cm(-2) current density. The Tafel slope for that case is 43 mV per decade, which is the lowest ever achieved for MoS2-based electrocatalyst in alkaline media. The catalyst is highly stable for at least 13 h, with no decrease in the current density. This simple, cost-effective, and environmentally friendly methodology can pave the way for exploitation of MoSx@NiO composite catalysts not only for water splitting, but also for other applications such as lithium ion batteries, and fuel cells.

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