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  • 1.
    Ail, Ujwala
    et al.
    Linköping University, Department of Science and Technology, Physics and Electronics. Linköping University, Faculty of Science & Engineering.
    Jafari, Mohammad Javad
    Linköping University, Department of Physics, Chemistry and Biology, Molecular Physics. Linköping University, Faculty of Science & Engineering.
    Wang, Hui
    Linköping University, Department of Science and Technology. Linköping University, Faculty of Science & Engineering.
    Ederth, Thomas
    Linköping University, Department of Physics, Chemistry and Biology, Molecular Physics. Linköping University, Faculty of Science & Engineering.
    Berggren, Magnus
    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.
    Thermoelectric Properties of Polymeric Mixed Conductors2016In: Advanced Functional Materials, ISSN 1616-301X, E-ISSN 1616-3028, Vol. 26, no 34, p. 6288-6296Article in journal (Refereed)
    Abstract [en]

    The thermoelectric (TE) phenomena are intensively explored by the scientific community due to the rather inefficient way energy resources are used with a large fraction of energy wasted in the form of heat. Among various materials, mixed ion-electron conductors (MIEC) are recently being explored as potential thermoelectrics, primarily due to their low thermal conductivity. The combination of electronic and ionic charge carriers in those inorganic or organic materials leads to complex evolution of the thermovoltage (Voc) with time, temperature, and/or humidity. One of the most promising organic thermoelectric materials, poly(3,4-ethyelenedioxythiophene)-polystyrene sulfonate (PEDOT-PSS), is an MIEC. A previous study reveals that at high humidity, PEDOT-PSS undergoes an ionic Seebeck effect due to mobile protons. Yet, this phenomenon is not well understood. In this work, the time dependence of the Voc is studied and its behavior from the contribution of both charge carriers (holes and protons) is explained. The presence of a complex reorganization of the charge carriers promoting an internal electrochemical reaction within the polymer film is identified. Interestingly, it is demonstrated that the time dependence behavior of Voc is a way to distinguish between three classes of polymeric materials: electronic conductor, ionic conductor, and mixed ionic–electronic conductor

  • 2.
    Ajjan, Fátima
    et al.
    Linköping University, Department of Physics, Chemistry and Biology, Biomolecular and Organic Electronics. Linköping University, Faculty of Science & Engineering.
    Javad Jafari, Mohammad
    Linköping University, Department of Physics, Chemistry and Biology, Molecular Physics. Linköping University, Faculty of Science & Engineering.
    Rebis, T.
    Poznan University of Tech, Poland.
    Ederth, Thomas
    Linköping University, Department of Physics, Chemistry and Biology, Molecular Physics. Linköping University, Faculty of Science & Engineering.
    Inganäs, Olle
    Linköping University, Department of Physics, Chemistry and Biology, Biomolecular and Organic Electronics. Linköping University, Faculty of Science & Engineering.
    Spectroelectrochemical investigation of redox states in a polypyrrole/lignin composite electrode material2015In: Journal of Materials Chemistry A, ISSN 2050-7488, Vol. 3, no 24, p. 12927-12937Article in journal (Refereed)
    Abstract [en]

    We report spectroelectrochemical studies to investigate the charge storage mechanism of composite polypyrrole/lignin electrodes. Renewable bioorganic electrode materials were produced by electropolymerization of pyrrole in the presence of a water-soluble lignin derivative acting as a dopant. The resulting composite exhibited enhanced charge storage abilities due to a lignin-based faradaic process, which was expressed after repeated electrochemical redox of the material. The in situ FTIR spectroelectrochemistry results show the formation of quinone groups, and reversible oxidation-reduction of these groups during charge-discharge experiments in the electrode materials. The most significant IR bands include carbonyl absorption near 1705 cm(-1), which is attributed to the creation of quinone moieties during oxidation, and absorption at 1045 cm(-1) which is due to hydroquinone moieties.

  • 3.
    Golabi, Mohsen
    et al.
    Linköping University, Department of Physics, Chemistry and Biology, Biosensors and Bioelectronics. Linköping University, Faculty of Science & Engineering.
    Jafari, Mohammad Javad
    Linköping University, Department of Physics, Chemistry and Biology, Molecular Physics. Linköping University, Faculty of Science & Engineering.
    Jager, Edwin
    Linköping University, Department of Physics, Chemistry and Biology, Biosensors and Bioelectronics. Linköping University, Faculty of Science & Engineering.
    Turner, Anthony
    Linköping University, Department of Physics, Chemistry and Biology, Biosensors and Bioelectronics. Linköping University, Faculty of Science & Engineering.
    Ederth, Thomas
    Linköping University, Department of Physics, Chemistry and Biology, Molecular Physics. Linköping University, Faculty of Science & Engineering.
    ATR-FTIR: a simple and rapid tool for bacterial resistance detection2015In: Conference on Advanced Vibrational Spectroscopy - ICAVS, Vienna, Austria, 12- 17 July 2015., 2015Conference paper (Refereed)
  • 4.
    Golabi, Mohsen
    et al.
    Linköping University, Faculty of Science & Engineering. Linköping University, Department of Physics, Chemistry and Biology, Biosensors and Bioelectronics.
    Padiolleau, Laurence
    Linköping University, Department of Physics, Chemistry and Biology, Biosensors and Bioelectronics. Linköping University, Faculty of Science & Engineering. Cranfield University, England.
    Chen, Xi
    Linköping University, Department of Physics, Chemistry and Biology, Biosensors and Bioelectronics. Linköping University, Faculty of Science & Engineering. University of Dundee, Scotland.
    Jafari, Mohammad Javad
    Linköping University, Department of Physics, Chemistry and Biology, Molecular Physics. Linköping University, Faculty of Science & Engineering.
    Sheikhzadeh, Elham
    Linköping University, Department of Physics, Chemistry and Biology, Biosensors and Bioelectronics. Linköping University, Faculty of Science & Engineering. Ferdowsi University of Mashhad, Iran.
    Turner, Anthony
    Linköping University, Department of Physics, Chemistry and Biology, Biosensors and Bioelectronics. Linköping University, Faculty of Science & Engineering.
    Jager, Edwin
    Linköping University, Department of Physics, Chemistry and Biology, Biosensors and Bioelectronics. Linköping University, Faculty of Science & Engineering.
    Beni, Valerio
    Linköping University, Department of Physics, Chemistry and Biology. Linköping University, Faculty of Science & Engineering. Acreo Swedish ICT AB, Sweden.
    Doping Polypyrrole Films with 4-N-Pentylphenylboronic Acid to Enhance Affinity towards Bacteria and Dopamine2016In: PLoS ONE, ISSN 1932-6203, E-ISSN 1932-6203, Vol. 11, no 11, article id e0166548Article in journal (Refereed)
    Abstract [en]

    Here we demonstrate the use of a functional dopant as a fast and simple way to tune the chemical affinity and selectivity of polypyrrole films. More specifically, a boronic-functionalised dopant, 4-N-Pentylphenylboronic Acid (PBA), was used to provide to polypyrrole films with enhanced affinity towards diols. In order to prove the proposed concept, two model systems were explored: (i) the capture and the electrochemical detection of dopamine and (ii) the adhesion of bacteria onto surfaces. The chemisensor, based on overoxidised polypyrrole boronic doped film, was shown to have the ability to capture and retain dopamine, thus improving its detection; furthermore the chemisensor showed better sensitivity in comparison with overoxidised perchlorate doped films. The adhesion of bacteria, Deinococcus proteolyticus, Escherichia coli, Streptococcus pneumoniae and Klebsiella pneumoniae, onto the boric doped polypyrrole film was also tested. The presence of the boronic group in the polypyrrole film was shown to favour the adhesion of sugar-rich bacterial cells when compared with a control film (Dodecyl benzenesulfonate (DBS) doped film) with similar morphological and physical properties. The presented single step synthesis approach is simple and fast, does not require the development and synthesis of functional monomers, and can be easily expanded to the electrochemical, and possibly chemical, fabrication of novel functional surfaces and interfaces with inherent pre-defined sensing and chemical properties.

  • 5.
    Jafari, Mohammad Javad
    Linköping University, Department of Physics, Chemistry and Biology, Molecular Physics. Linköping University, Faculty of Science & Engineering.
    Application of Vibrational Spectroscopy in Organic Electronics2017Doctoral thesis, comprehensive summary (Other academic)
    Abstract [en]

    The rapid technological developments enforce us to live in an increasingly electronic world, and the revolutionary usage of conjugated polymers in electronics in the late 1970s accelerated these developments, based on the unique characteristics of conjugated polymers, such as low cost, easy processing, mechanical flexibility, large-area application and compatibility with a variety of substrates. Organic electronic devices are commercially available in the form of, for example, solar cells, transistors, and organic light-emitting diode (OLED) displays. Scientists work on electroactive polymers to enhance their chemical, electrical and mechanical properties, to improve parameters such as charge carrier mobility and doping capacity, in order to reach acceptable efficiency and stability to fabricate organic electronic devices. A comprehensive understanding of the changes in chemical structure, in response to external factors such as applied potential and temperature gradients, which can disturb the chemical equilibrium of the constituent materials, and of the conduction mechanisms of the operating devices, can help to enhance the performance of organic electronics devices. Vibrational spectroscopy is a powerful analytical method for in-situ monitoring of such chemical or electrochemical reactions and associated structural changes of conjugated polymers in a working device.

    In this thesis, Fourier-transform infrared (FTIR) spectroscopy has been used to study the structural changes in electroactive organic materials, in response to chemical or electrochemical reactions, and to study electrical and thermal conduction mechanisms in different organic electronic devices. FTIR microscopy was used to approach a realistic conduction mechanism by time-resolved chemical imaging of active materials in planar light-emitting electrochemical cells (LECs), investigated as an alternative to organic light emitting diodes (OLEDs). These chemical images are used for in-situ mapping of anion density profiles, polymer doping, and dynamic junction formation in the active layer under an applied bias. Results confirm the electrochemical doping model and help the systematic improvement of function and manufacture of LECs. Mixed ion-electron polymeric conductor materials such as PEDOT-PSS are used as active materials in organic thermoelectric generators (OTEGs), where charge carrier transport through the active layer promotes internal electrochemical reactions under a temperature gradient. FTIR microscopy and FTIR-attenuated total reflection (FTIR-ATR) were used to study thermoelectric and electrical properties of the conducting polymers. Recently, electrochemical supercapacitors have emerged as an alternative to conventional batteries, and polymeric materials are used to design polymer electrodes for renewable energy storage. To understand the charge transfer and structural changes of the polymer during the redox reaction, we have used FTIR-ATR as a tool for the in-situ spectroelectrochemical study of redox states in polypyrrole/lignin composites; we clarified the structural changes in the materials during charging and discharging of the composite. In further work, FTIR-ATR was also used for in-situ spectroelectrochemical studies of PEDOT:Cl, to monitor the effects of dissolved oxygen on PEDOT:Cl films, which are used as electrodes in renewable energy technologies. Further, time-resolved oxygen reduction reactions of PEDOT:Cl have been studied via polarization-modulation infrared reflection-absorption spectroscopy (PM-IRAS) to reveal chemical changes in electrochemically doped PEDOT upon exposure to oxygen.

    Taken together, these studies provide an advancement in the use of infrared spectroscopy as a tool to understand electroactive materials under wet conditions, and have provided detailed chemical and electrochemical information of materials and devices under operation, that is not easily accessible with other methods.

    List of papers
    1. Time-Resolved Chemical Mapping in Light-Emitting Electrochemical Cells
    Open this publication in new window or tab >>Time-Resolved Chemical Mapping in Light-Emitting Electrochemical Cells
    2017 (English)In: ACS Applied Materials and Interfaces, ISSN 1944-8244, E-ISSN 1944-8252, Vol. 9, no 3, p. 2747-2757Article in journal (Refereed) Published
    Abstract [en]

    An understanding of the doping and ion distributions in light-emitting electrochemical cells (LECs) is required to approach a realistic conduction model which can precisely explain the electrochemical reactions, p-n junction formation, and ion dynamics in the active layer and to provide relevant information about LECs for systematic improvement of function and manufacture. Here, Fourier-transform infrared (FTIR) microscopy is used to monitor anion density profile and polymer structure in situ and for time-resolved mapping of electrochemical doping in an LEC under bias. The results are in very good agreement with the electrochemical doping model with respect to ion redistribution and formation of a dynamic p-n junction in the active layer. We also physically slow ions by decreasing the working temperature and study frozen-junction formation and immobilization of ions in a fixed-junction LEC device by FTIR imaging. The obtained results show irreversibility of the ion redistribution and polymer doping in a fixed-junction device. In addition, we demonstrate that infrared microscopy is a useful tool for in situ characterization of electroactive organic materials.

    Place, publisher, year, edition, pages
    AMER CHEMICAL SOC, 2017
    Keywords
    light-emitting electrochemical cell; FTIR spectroscopic imaging electrochemical doping doping profile; ion distribution; dynamic p-n junction; infrared microspectroscopy; principal component analysis
    National Category
    Inorganic Chemistry
    Identifiers
    urn:nbn:se:liu:diva-135398 (URN)10.1021/acsami.6b14162 (DOI)000392909500086 ()28032741 (PubMedID)
    Note

    Funding Agencies|Power Papers project from the Knut and Alice Wallenberg Foundation [2011-0050]; Swedish Government Strategic Research Area in Materials Science on Functional Materials at Linkoping University [SFO-Mat-LiU 2009-00971]

    Available from: 2017-03-14 Created: 2017-03-14 Last updated: 2017-11-29
    2. Thermoelectric Properties of Polymeric Mixed Conductors
    Open this publication in new window or tab >>Thermoelectric Properties of Polymeric Mixed Conductors
    Show others...
    2016 (English)In: Advanced Functional Materials, ISSN 1616-301X, E-ISSN 1616-3028, Vol. 26, no 34, p. 6288-6296Article in journal (Refereed) Published
    Abstract [en]

    The thermoelectric (TE) phenomena are intensively explored by the scientific community due to the rather inefficient way energy resources are used with a large fraction of energy wasted in the form of heat. Among various materials, mixed ion-electron conductors (MIEC) are recently being explored as potential thermoelectrics, primarily due to their low thermal conductivity. The combination of electronic and ionic charge carriers in those inorganic or organic materials leads to complex evolution of the thermovoltage (Voc) with time, temperature, and/or humidity. One of the most promising organic thermoelectric materials, poly(3,4-ethyelenedioxythiophene)-polystyrene sulfonate (PEDOT-PSS), is an MIEC. A previous study reveals that at high humidity, PEDOT-PSS undergoes an ionic Seebeck effect due to mobile protons. Yet, this phenomenon is not well understood. In this work, the time dependence of the Voc is studied and its behavior from the contribution of both charge carriers (holes and protons) is explained. The presence of a complex reorganization of the charge carriers promoting an internal electrochemical reaction within the polymer film is identified. Interestingly, it is demonstrated that the time dependence behavior of Voc is a way to distinguish between three classes of polymeric materials: electronic conductor, ionic conductor, and mixed ionic–electronic conductor

    Place, publisher, year, edition, pages
    Wiley-VCH Verlagsgesellschaft, 2016
    National Category
    Inorganic Chemistry
    Identifiers
    urn:nbn:se:liu:diva-133171 (URN)10.1002/adfm.201601106 (DOI)000383609300015 ()2-s2.0-84978042566 (Scopus ID)
    Funder
    EU, European Research Council, 307596
    Note

    Funding agencies: European Research Council (ERC) [307596]

    Available from: 2016-12-12 Created: 2016-12-12 Last updated: 2018-08-31Bibliographically approved
    3. Acido-basic control of the thermoelectric properties of poly(3,4-ethylenedioxythiophene)tosylate (PEDOT-Tos) thin films
    Open this publication in new window or tab >>Acido-basic control of the thermoelectric properties of poly(3,4-ethylenedioxythiophene)tosylate (PEDOT-Tos) thin films
    Show others...
    2015 (English)In: Journal of Materials Chemistry C, ISSN 2050-7526, E-ISSN 2050-7534, Vol. 3, p. 10616-10623Article in journal (Refereed) Published
    Abstract [en]

    PEDOT-Tos is one of the conducting polymers that displays the most promising thermoelectric properties. Until now, it has been utterly difficult to control all the synthesis parameters and the morphology governing the thermoelectric properties. To improve our understanding of this material, we study the variation in the thermoelectric properties by a simple acido-basic treatment. The emphasis of this study is to elucidate the chemical changes induced by acid (HCl) or base (NaOH) treatment in PEDOT-Tos thin films using various spectroscopic and structural techniques. We could identify changes in the nanoscale morphology due to anion exchange between tosylate and Cl- or OH-. But, we identified that changing the pH leads to a tuning of the oxidation level of the polymer, which can explain the changes in thermoelectric properties. Hence, a simple acid-base treatment allows finding the optimum for the power factor in PEDOT-Tos thin films.

    Place, publisher, year, edition, pages
    Royal Society of Chemistry, 2015
    National Category
    Polymer Chemistry Textile, Rubber and Polymeric Materials
    Identifiers
    urn:nbn:se:liu:diva-121977 (URN)10.1039/C5TC01952D (DOI)000363251600035 ()
    Note

    Funding agencies: European Research Council (ERC) [307596]

    Available from: 2015-10-14 Created: 2015-10-14 Last updated: 2018-08-20Bibliographically approved
    4. Spectroelectrochemical investigation of redox states in a polypyrrole/lignin composite electrode material
    Open this publication in new window or tab >>Spectroelectrochemical investigation of redox states in a polypyrrole/lignin composite electrode material
    Show others...
    2015 (English)In: Journal of Materials Chemistry A, ISSN 2050-7488, Vol. 3, no 24, p. 12927-12937Article in journal (Refereed) Published
    Abstract [en]

    We report spectroelectrochemical studies to investigate the charge storage mechanism of composite polypyrrole/lignin electrodes. Renewable bioorganic electrode materials were produced by electropolymerization of pyrrole in the presence of a water-soluble lignin derivative acting as a dopant. The resulting composite exhibited enhanced charge storage abilities due to a lignin-based faradaic process, which was expressed after repeated electrochemical redox of the material. The in situ FTIR spectroelectrochemistry results show the formation of quinone groups, and reversible oxidation-reduction of these groups during charge-discharge experiments in the electrode materials. The most significant IR bands include carbonyl absorption near 1705 cm(-1), which is attributed to the creation of quinone moieties during oxidation, and absorption at 1045 cm(-1) which is due to hydroquinone moieties.

    Place, publisher, year, edition, pages
    ROYAL SOC CHEMISTRY, 2015
    National Category
    Materials Chemistry
    Identifiers
    urn:nbn:se:liu:diva-120069 (URN)10.1039/c5ta00788g (DOI)000356022800044 ()
    Note

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

    Available from: 2015-07-06 Created: 2015-07-06 Last updated: 2017-12-04
    5. Oxygen-induced doping on reduced PEDOT
    Open this publication in new window or tab >>Oxygen-induced doping on reduced PEDOT
    Show others...
    2017 (English)In: Journal of Materials Chemistry A, ISSN 2050-7488, Vol. 5, no 9, p. 4404-4412Article in journal (Refereed) Published
    Abstract [en]

    The conducting polymer poly(3,4-ethylenedioxythiophene) (PEDOT) has shown promise as air electrode in renewable energy technologies like metal-air batteries and fuel cells. PEDOT is based on atomic elements of high abundance and is synthesized at low temperature from solution. The mechanism of oxygen reduction reaction (ORR) over chemically polymerized PEDOT: Cl still remains controversial with eventual role of transition metal impurities. However, regardless of the mechanistic route, we here demonstrate yet another key active role of PEDOT in the ORR mechanism. Our study demonstrates the decoupling of conductivity (intrinsic property) from electrocatalysis (as an extrinsic phenomenon) yielding the evidence of doping of the polymer by oxygen during ORR. Hence, the PEDOT electrode is electrochemically reduced (undoped) in the voltage range of ORR regime, but O-2 keeps it conducting; ensuring PEDOT to act as an electrode for the ORR. The interaction of oxygen with the polymer electrode is investigated with a battery of spectroscopic techniques.

    Place, publisher, year, edition, pages
    ROYAL SOC CHEMISTRY, 2017
    National Category
    Materials Chemistry
    Identifiers
    urn:nbn:se:liu:diva-136229 (URN)10.1039/c6ta10521a (DOI)000395926100019 ()
    Note

    Funding Agencies|European Research Council (ERC) [307596]; Knut and Alice Wallenberg foundation; Wenner-Gren Foundations; Swedish Research Council; Swedish Foundation for Strategic Research [0-3D]; Swedish Government Strategic Research Area in Materials Science on Functional Materials at Linkoping University [2009 00971]

    Available from: 2017-03-31 Created: 2017-03-31 Last updated: 2018-05-07
  • 6.
    Jafari, Mohammad Javad
    et al.
    Linköping University, Department of Physics, Chemistry and Biology, Molecular Physics. Linköping University, Faculty of Science & Engineering.
    Liu, Jiang
    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, Faculty of Science & Engineering.
    Ederth, Thomas
    Linköping University, Department of Physics, Chemistry and Biology, Molecular Physics. Linköping University, Faculty of Science & Engineering.
    Time-Resolved Chemical Mapping in Light-Emitting Electrochemical Cells2017In: ACS Applied Materials and Interfaces, ISSN 1944-8244, E-ISSN 1944-8252, Vol. 9, no 3, p. 2747-2757Article in journal (Refereed)
    Abstract [en]

    An understanding of the doping and ion distributions in light-emitting electrochemical cells (LECs) is required to approach a realistic conduction model which can precisely explain the electrochemical reactions, p-n junction formation, and ion dynamics in the active layer and to provide relevant information about LECs for systematic improvement of function and manufacture. Here, Fourier-transform infrared (FTIR) microscopy is used to monitor anion density profile and polymer structure in situ and for time-resolved mapping of electrochemical doping in an LEC under bias. The results are in very good agreement with the electrochemical doping model with respect to ion redistribution and formation of a dynamic p-n junction in the active layer. We also physically slow ions by decreasing the working temperature and study frozen-junction formation and immobilization of ions in a fixed-junction LEC device by FTIR imaging. The obtained results show irreversibility of the ion redistribution and polymer doping in a fixed-junction device. In addition, we demonstrate that infrared microscopy is a useful tool for in situ characterization of electroactive organic materials.

  • 7.
    Kaushik, Priya Darshni
    et al.
    Linköping University, Department of Physics, Chemistry and Biology, Semiconductor Materials. Linköping University, Faculty of Science & Engineering. Jamia Millia Islamia, India.
    Aziz, Anver
    Jamia Millia Islamia, India.
    Siddiqui, Azher M.
    Jamia Millia Islamia, India.
    Greczynski, Grzegorz
    Linköping University, Department of Physics, Chemistry and Biology, Thin Film Physics. Linköping University, Faculty of Science & Engineering.
    Jafari, Mohammad Javad
    Linköping University, Department of Physics, Chemistry and Biology, Molecular Physics. Linköping University, Faculty of Science & Engineering.
    Lakshmi, G. B. V. S.
    Interuniv Accelerator Centre, India.
    Avasthi, D. K.
    Interuniv Accelerator Centre, India; Amity Institute Nanotechnol, India.
    Syväjärvi, Mikael
    Linköping University, Department of Physics, Chemistry and Biology, Semiconductor Materials. Linköping University, Faculty of Science & Engineering.
    Yazdi, Gholamreza
    Linköping University, Department of Physics, Chemistry and Biology, Semiconductor Materials. Linköping University, Faculty of Science & Engineering.
    Modifications in structural, optical and electrical properties of epitaxial graphene on SiC due to 100 MeV silver ion irradiation2018In: Materials Science in Semiconductor Processing, ISSN 1369-8001, E-ISSN 1873-4081, Vol. 74, p. 122-128Article in journal (Refereed)
    Abstract [en]

    Epitaxial graphene (EG) on silicon carbide (SiC) is a combination of two robust materials that are excellent candidates for post silicon electronics. In this work, we systematically investigate structural changes in SiC substrate as well as graphene on SiC and explore the potential for controlled applications due to 100 MeV silver swift heavy ion (SHI) irradiation. Raman spectroscopy showed fluence dependent decrease in intensity of first and second order modes of SiC, along with decrease in Relative Raman Intensity upon ion irradiation. Similarly, Fourier-transform infrared (FTIR) showed fluence dependent decrease in Si-C bond intensity with presence of C = O, Si-O-Si, Si-Si and C-H bond showing introduction of vacancy, substitutional and sp(3) defects in both graphene and SiC. C1s spectra in XPS shows decrease in C = C graphitic peak and increase in interfacial layer following ion irradiation. Reduction in monolayer coverage of graphene after ion irradiation was observed by Scanning electron microscopy (SEM). Further, UV-Visible spectroscopy showed increase in absorbance of EG on SiC at increasing fluence. I-V characterization showed fluence dependent increase in resistance from 62.9 O in pristine sample to 480.1 Omega in sample irradiated at 6.6 x 10(12) ions/cm(2) fluence. The current study demonstrates how SHI irradiation can be used to tailor optoelectronic applicability of EG on SiC.

  • 8.
    Mitraka, Evangelia
    et al.
    Linköping University, Department of Science and Technology, Physics and Electronics. Linköping University, Faculty of Science & Engineering.
    Jafari, Mohammad Javad
    Linköping University, Department of Physics, Chemistry and Biology, Molecular Physics. Linköping University, Faculty of Science & Engineering.
    Vagin, Mikhail
    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.
    Ederth, Thomas
    Linköping University, Department of Physics, Chemistry and Biology, Molecular Physics. Linköping University, Faculty of Science & Engineering.
    Berggren, 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.
    Crispin, Xavier
    Linköping University, Department of Science and Technology, Physics and Electronics. Linköping University, Faculty of Science & Engineering.
    Oxygen-induced doping on reduced PEDOT2017In: Journal of Materials Chemistry A, ISSN 2050-7488, Vol. 5, no 9, p. 4404-4412Article in journal (Refereed)
    Abstract [en]

    The conducting polymer poly(3,4-ethylenedioxythiophene) (PEDOT) has shown promise as air electrode in renewable energy technologies like metal-air batteries and fuel cells. PEDOT is based on atomic elements of high abundance and is synthesized at low temperature from solution. The mechanism of oxygen reduction reaction (ORR) over chemically polymerized PEDOT: Cl still remains controversial with eventual role of transition metal impurities. However, regardless of the mechanistic route, we here demonstrate yet another key active role of PEDOT in the ORR mechanism. Our study demonstrates the decoupling of conductivity (intrinsic property) from electrocatalysis (as an extrinsic phenomenon) yielding the evidence of doping of the polymer by oxygen during ORR. Hence, the PEDOT electrode is electrochemically reduced (undoped) in the voltage range of ORR regime, but O-2 keeps it conducting; ensuring PEDOT to act as an electrode for the ORR. The interaction of oxygen with the polymer electrode is investigated with a battery of spectroscopic techniques.

  • 9.
    Ouyang, Liangqi
    et al.
    Linköping University, Department of Physics, Chemistry and Biology, Biomolecular and Organic Electronics. Linköping University, Faculty of Science & Engineering.
    Jafari, Mohammad Javad
    Linköping University, Department of Physics, Chemistry and Biology, Molecular Physics. Linköping University, Faculty of Science & Engineering.
    Wanzhu, Cai
    Linköping University, Department of Physics, Chemistry and Biology, Biomolecular and Organic Electronics. Linköping University, Faculty of Science & Engineering.
    Ever Aguirre, Luis
    Linköping University, Department of Physics, Chemistry and Biology, Biomolecular and Organic Electronics. 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.
    Ederth, Thomas
    Linköping University, Department of Physics, Chemistry and Biology, Molecular Physics. Linköping University, Faculty of Science & Engineering.
    Inganäs, Olle
    Linköping University, Department of Physics, Chemistry and Biology, Biomolecular and Organic Electronics. Linköping University, Faculty of Science & Engineering.
    The contraction of PEDOT films formed on a macromolecular liquid-like surface2018In: Journal of Materials Chemistry C, ISSN 2050-7526, E-ISSN 2050-7534, Vol. 6, no 3, p. 654-660Article in journal (Refereed)
    Abstract [en]

    Vapour phase polymerized (VPP) PEDOT obtained using triblock copolymer PEG-PPG-PEG: Fe(III) tosylate polymeric oxidative layers has shown record-high conductivity and unique thermoelectric properties. These properties are related to the molecular weight, morphology and doping of PEDOT. Here we show that in its unwashed condition, the PEDOT chain adopts a neutral benzenoid conformation. The polymer chain converts into the charged quinoid structure after the removal of oxidizers with solvent washing. X-ray diffraction results suggest that the dopant is also incorporated into the packed polymer after the washing process. The changes in the chain structure and doping lead to the characteristic polaron and bipolaron absorption in the 800 and 1200 nm range. We observed a large contraction of the film after washing that is likely due to these changes, along with the removal of excessive polymer: oxidizer trapped in the PEDOT matrix. The contraction of films can be completely suppressed by mechanical clamping. PEDOT films without contraction show both a higher conductivity and higher optical transparency.

  • 10.
    Ouyang, Liangqi
    et al.
    Linköping University, Department of Physics, Chemistry and Biology, Biomolecular and Organic Electronics. Linköping University, Faculty of Science & Engineering.
    Musumeci, Chiara
    Linköping University, Department of Physics, Chemistry and Biology, Biomolecular and Organic Electronics. Linköping University, Faculty of Science & Engineering.
    Jafari, Mohammad Javad
    Linköping University, Department of Physics, Chemistry and Biology, Molecular Physics. Linköping University, Faculty of Science & Engineering.
    Ederth, Thomas
    Linköping University, Department of Physics, Chemistry and Biology, Molecular Physics. Linköping University, Faculty of Science & Engineering.
    Inganäs, Olle
    Linköping University, Department of Physics, Chemistry and Biology, Biomolecular and Organic Electronics. Linköping University, Faculty of Science & Engineering.
    Imaging the Phase Separation Between PEDOT and Polyelectrolytes During Processing of Highly Conductive PEDOT:PSS Films2015In: ACS Applied Materials and Interfaces, ISSN 1944-8244, E-ISSN 1944-8252, Vol. 7, no 35, p. 19764-19773Article in journal (Refereed)
    Abstract [en]

    Treating PEDOT:PSS (Clevios) with certain additives, such as ethylene glycol (EG), dimethyl sulfoxide (DMSO) and sorbitol, has been shown to increase the conductivity of this material from roughly 1 to nearly 1000 S/cm. Using a slow drying method, we show that the additive induced a separation between free PSS and reorganized PEDOT:PSS complexes in the highly conductive PEDOT:PSS films. Additives (DMSO, DEG, and PEG 400) were included in PEDOT:PSS aqueous dispersions at large volume fractions. The mixtures were slowly dried under room conditions. During drying, the evaporation of water resulted in an additive-rich solvent mixture from which the reorganized PEDOT:PSS complexes aggregated " into a dense film while free PSS remained in the solution. Upon complete drying, PSS formed a transparent rim film around the conducting PEDOT film. The chemical compositions of the two phases were studied using an infrared microscope. This removal of PSS resulted in more compact packing of PEDOT molecules, as confirmed by X-ray diffraction measurements. X-ray photoelectron spectroscopy and atomic force microscope measurements suggested the enrichment of PEDOT on the film surface after PSS separation. Through a simple drying process in an additive-containing dispersion, the conductivity of PEDOT films increased from 0.1 to 200-400 S/cm. Through this method, we confirmed the existence of two phases in additive-treated and highly conductive PEDOT:PSS films. The proper separation between PSS and PEDOT will be of relevance in designing strategies to process high-performance plastic electrodes.

  • 11.
    Parlak, Onur
    et al.
    Linköping University, Department of Physics, Chemistry and Biology, Biosensors and Bioelectronics. Linköping University, Faculty of Science & Engineering.
    Beyazit, Selim
    CNRS Enzyme and Cell Engineering Laboratory, Université de Technologie de Compiègn Rue Roger Couttolenc, Compiègne, Cedex, France.
    Jafari, Mohammed J.
    Linköping University, Department of Physics, Chemistry and Biology, Molecular Physics. Linköping University, Faculty of Science & Engineering.
    Tse Sum Bui, Bernadette
    CNRS Enzyme and Cell Engineering Laboratory, Université de Technologie de Compiègn Rue Roger Couttolenc, Compiègne, Cedex, France.
    Haupt, Karsten
    CNRS Enzyme and Cell Engineering Laboratory, Université de Technologie de Compiègn Rue Roger Couttolenc, Compiègne, Cedex, France.
    Tiwari, Ashutosh
    Linköping University, Department of Physics, Chemistry and Biology, Biosensors and Bioelectronics. Linköping University, Faculty of Science & Engineering. Tekidag AB, UCS, Linköping, Sweden.
    Turner, Anthony
    Linköping University, Department of Physics, Chemistry and Biology, Biosensors and Bioelectronics. Linköping University, Faculty of Science & Engineering.
    Light-triggered switchable graphene-polymer hybrid bioelectronics2016In: Advanced Materials Interfaces, ISSN 2196-7350, Vol. 3, no 2, p. 1500353-1-1500353-7Article in journal (Refereed)
    Abstract [en]

    A light-switchable graphene interface to control and regulate electrobiocatalysis in a nanoconfined space is reported for the first time. The development of switchable and/or tunable interfaces on 2D nanosurfaces endowed with desirable functionalities, and incorporation of these interfaces into remote controlled biodevices, is a rapidly emerging area in bioelectronics.

  • 12.
    Parlak, Onur
    et al.
    Linköping University, Department of Physics, Chemistry and Biology, Biosensors and Bioelectronics. Linköping University, Faculty of Science & Engineering.
    Beyazit, Selim
    Sorbonne Universités, Université de Technologie de Compiègne, CNRS Laboratory for Enzyme and Cell Engineering, France.
    Jafari, Mohammed J.
    Linköping University, Department of Physics, Chemistry and Biology, Molecular Physics. Linköping University, Faculty of Science & Engineering.
    Tse Sum Bui, Bernadette
    Sorbonne Universités, Université de Technologie de Compiègne, CNRS Laboratory for Enzyme and Cell Engineering, France.
    Haupt, Karsten
    Sorbonne Universités, Université de Technologie de Compiègne, CNRS Laboratory for Enzyme and Cell Engineering, France.
    Tiwari, Ashutosh
    Tekidag AB, UCS, Mjärdevi Science Park, Linköping Sweden.
    Turner, Anthony P. F
    Linköping University, Department of Physics, Chemistry and Biology, Biosensors and Bioelectronics. Linköping University, Faculty of Science & Engineering.
    Light-triggered on/off-switchable graphene-based bioelectronicsManuscript (preprint) (Other academic)
  • 13.
    Patra, Hirak Kumar
    et al.
    Linköping University, Department of Clinical and Experimental Medicine, Division of Cell Biology. Linköping University, Faculty of Medicine and Health Sciences. Department of Chemical Engineering and Biotechnology, Cambridge University, Cambridge, UK; Wolfson College, University of Cambridge, Cambridge, UK.
    Azharuddin, Mohammad
    Linköping University, Department of Clinical and Experimental Medicine, Division of Clinical Chemistry. Linköping University, Faculty of Medicine and Health Sciences.
    Islam, Mohammad Mirazul
    Linköping University, Department of Clinical and Experimental Medicine, Division of Cell Biology. Linköping University, Faculty of Medicine and Health Sciences. Massachusetts Eye and Ear and Schepens Eye Research Institute, Department of Ophthalmology, Harvard Medical School, Boston, USA.
    Papapavlou, Georgia
    Linköping University, Department of Clinical and Experimental Medicine, Division of Neuro and Inflammation Science. Linköping University, Faculty of Medicine and Health Sciences.
    Deb, Suryyani
    Linköping University, Department of Clinical and Experimental Medicine, Division of Microbiology and Molecular Medicine. Linköping University, Faculty of Medicine and Health Sciences. Department of Biochemistry, University of Calcutta, Calcutta, India; Department of Biotechnology, Maulana Abul Kalam Azad University of Technology (MAKAUT), West Bengal, India.
    Osterrieth, Johannes
    Department of Chemical Engineering and Biotechnology, Cambridge University, Philippa Fawcett Drive, Cambridge, UK.
    Zhu, Geyunjian Harry
    Department of Chemical Engineering and Biotechnology, Cambridge University, Philippa Fawcett Drive, Cambridge, UK.
    Romu, Thobias
    Linköping University, Faculty of Science & Engineering. Linköping University, Center for Medical Image Science and Visualization (CMIV).
    Dhara, Ashis K.
    Centre for Image Analysis, Uppsala University, Uppsala, Sweden; Department of Electrical Engineering, National Institute of Technology Durgapur, West Bengal, India.
    Jafari, Mohammad Javad
    Linköping University, Department of Physics, Chemistry and Biology, Molecular Physics. Linköping University, Faculty of Science & Engineering.
    Gadheri, Amineh
    Department of Oncology‐Pathology, Karolinska Institute, Stockholm, Sweden.
    Hinkula, Jorma
    Linköping University, Department of Clinical and Experimental Medicine, Division of Hematopoiesis and Developmental Biology. Linköping University, Faculty of Medicine and Health Sciences.
    Rajan, Madhavan S.
    Department of Ophthalmology, Cambridge University Hospitals NHS Trust and Vision and Eye Research Institute (VERI), Anglia Ruskin University, Cambridge, UK.
    Slater, Nigel K. H.
    Department of Chemical Engineering and Biotechnology, Cambridge University, Philippa Fawcett Drive, Cambridge, UK.
    Rational Nanotoolbox with Theranostic Potential for Medicated Pro-Regenerative Corneal Implants2019In: Advanced Functional Materials, ISSN 1616-301X, E-ISSN 1616-3028, article id 1903760Article in journal (Refereed)
    Abstract [en]

    Cornea diseases are a leading cause of blindness and the disease burden is exacerbated by the increasing shortage around the world for cadaveric donor corneas. Despite the advances in the field of regenerative medicine, successful transplantation of laboratory‐made artificial corneas is not fully realized in clinical practice. The causes of failure of such artificial corneal implants are multifactorial and include latent infections from viruses and other microbes, enzyme overexpression, implant degradation, extrusion or delayed epithelial regeneration. Therefore, there is an urgent unmet need for developing customized corneal implants to suit the host environment and counter the effects of inflammation or infection, which are able to track early signs of implant failure in situ. This work reports a nanotoolbox comprising tools for protection from infection, promotion of regeneration, and noninvasive monitoring of the in situ corneal environment. These nanosystems can be incorporated within pro‐regenerative biosynthetic implants, transforming them into theranostic devices, which are able to respond to biological changes following implantation.

    The full text will be freely available from 2020-07-15 00:01
  • 14.
    Patra, Hirak Kumar
    et al.
    Linköping University, Department of Clinical and Experimental Medicine, Division of Cell Biology. Linköping University, Faculty of Medicine and Health Sciences. Linköping University, Department of Physics, Chemistry and Biology, Biosensors and Bioelectronics.
    Sharma, Yashpal
    International Center for Materials Nanoarchitectonics, National Institute for Materials Science (NIMS), Sengen, Tsukuba, Ibaraki, Japan .
    Islam, Mohammad Mirazul
    Swedish Nanoscience Center, Karolinska Institute, Stockholm, Sweden.
    Jafari, Mohammad Javad
    Linköping University, Department of Physics, Chemistry and Biology, Molecular Physics. Linköping University, Faculty of Science & Engineering.
    Arul Murugan, N.
    Virtual Laboratory for Molecular Probes, Division of Theoretical Chemistry and Biology, School of Biotechnology, Royal Institute of Technology (KTH), Stockholm, Sweden .
    Kobayashi, Hisatoshi
    International Center for Materials Nanoarchitectonics, National Institute for Materials Science (NIMS), Sengen, Tsukuba, Ibaraki, Japan .
    Turner, Anthony
    Linköping University, Department of Physics, Chemistry and Biology, Biosensors and Bioelectronics. Linköping University, Faculty of Science & Engineering.
    Tiwari, Ashutosh
    Linköping University, Department of Physics, Chemistry and Biology, Biosensors and Bioelectronics. Linköping University, Faculty of Science & Engineering. International Center for Materials Nanoarchitectonics, National Institute for Materials Science (NIMS), Sengen, Tsukuba, Ibaraki, Japan ; Tekidag AB, UCS, Linköping, Sweden; Vinoba Bhave Research Institute, Saidabad, Allahabad, India .
    Inflammation-sensitive in situ smart scaffolding for regenerative medicine2016In: Nanoscale, ISSN 2040-3364, E-ISSN 2040-3372, Vol. 8, no 39, p. 17213-17222Article in journal (Refereed)
    Abstract [en]

    To cope with the rapid evolution of the tissue engineering field, it is now essential to incorporate the use of on-site responsive scaffolds. Therefore, it is of utmost importance to find new Intelligent biomaterials that can respond to the physicochemical changes in the microenvironment. In this present report, we have developed biocompatible stimuli responsive polyaniline-multiwalled carbon nanotube/poly(N-isopropylacrylamide), (PANI-MWCNT/PNIPAm) composite nanofiber networks and demonstrated the physiological temperature coordinated cell grafting phenomenon on its surface. The composite nanofibers were prepared by a two-step process initiated with an assisted in situ polymerization followed by electro-spinning. To obtain a smooth surface in individual nanofibers with the thinnest diameter, the component ratios and electrospinning conditions were optimized. The temperature-gated rearrangements of the molecular structure are characterized by FTIR spectroscopy with simultaneous macromolecular architecture changes reflected on the surface morphology, average diameter and pore size as determined by scanning electron microscopy. The stimuli responsiveness of the nanofibers has first been optimized with computational modeling of temperature sensitive components (coil-like and globular conformations) to tune the mechanism for temperature dependent interaction during in situ scaffolding with the cell membrane. The nanofiber networks show excellent biocompatibility, tested with fibroblasts and also show excellent sensitivity to inflammation to combat loco-regional acidosis that delay the wound healing process by an in vitro model that has been developed for testing the proposed responsiveness of the composite nanofiber networks. Cellular adhesion and detachment are regulated through physiological temperature and show normal proliferation of the grafted cells on the composite nanofibers. Thus, we report for the first time, the development of physiological temperature gated inflammation-sensitive smart biomaterials for advanced tissue regeneration and regenerative medicine.

  • 15.
    Tang, Zheng
    et al.
    Linköping University, Department of Physics, Chemistry and Biology, Biomolecular and Organic Electronics. Linköping University, The Institute of Technology.
    Tress, Wolfgang
    Linköping University, Department of Physics, Chemistry and Biology, Biomolecular and Organic Electronics. Linköping University, The Institute of Technology.
    Bao, Qinye
    Linköping University, Department of Physics, Chemistry and Biology, Surface Physics and Chemistry. Linköping University, The Institute of Technology.
    Jafari, Mohammad Javad
    Linköping University, Department of Physics, Chemistry and Biology, Molecular Physics. Linköping University, The Institute of Technology.
    Bergqvist, Jonas
    Linköping University, Department of Physics, Chemistry and Biology, Biomolecular and Organic Electronics. Linköping University, The Institute of Technology.
    Ederth, Thomas
    Linköping University, Department of Physics, Chemistry and Biology, Molecular Physics. Linköping University, The Institute of Technology.
    Andersson, Mats R.
    , Chalmers University of Technology, Göteborg, Sweden; University of South Australia, Australia.
    Inganäs, Olle
    Linköping University, Department of Physics, Chemistry and Biology, Biomolecular and Organic Electronics. Linköping University, The Institute of Technology.
    Improving Cathodes with a Polymer Interlayer in Reversed Organic Solar Cells2014In: Advanced Energy Materials, ISSN 1614-6832, Vol. 4, no 15, article id 1400643Article in journal (Refereed)
    Abstract [en]

    The effects of cathode modification by a conjugated polymer interlayer PFPA1 on the performance of reversed organic solar cells (substrate/cathode/active layer/transparent anode) based on different active material systems and different substrate electrodes are systematically investigated. A reduction of the work function irrespective of the substrate cathode used is observed upon the deposition of the PFPA1 interlayer, which is further related to an improved built-in electric field and open-circuit voltage. The amphiphilic character of the PFPA1 interlayer alters the surface energy of the substrate cathode, leading to the formation of a better active layer morphology aiding efficient exciton dissociation and photocurrent extraction in the modified solar cells. Hence, internal quantum efficiency is found to be significantly higher than that of their unmodified counterparts, while optically, the modified and unmodified solar cells are identical. Moreover, the deep highest occupied molecular orbital (HOMO) of the PFPA1 interlayer improves the selectivity for all investigated substrate cathodes, thus enhancing the fill factor.

  • 16.
    Tang, Zheng
    et al.
    Linköping University, Department of Physics, Chemistry and Biology, Biomolecular and Organic Electronics. Linköping University, The Institute of Technology.
    Tress, Wolfgang
    Linköping University, Department of Physics, Chemistry and Biology, Biomolecular and Organic Electronics. Linköping University, The Institute of Technology.
    Bao, Qinye
    Linköping University, Department of Physics, Chemistry and Biology, Surface Physics and Chemistry. Linköping University, The Institute of Technology.
    Jafari, Mohammad Javad
    Linköping University, Department of Physics, Chemistry and Biology, Molecular Physics. Linköping University, Faculty of Science & Engineering.
    Bergqvist, Jonas
    Linköping University, Department of Physics, Chemistry and Biology, Biomolecular and Organic Electronics. Linköping University, The Institute of Technology.
    Ederth, Thomas
    Linköping University, Department of Physics, Chemistry and Biology, Molecular Physics. Linköping University, Faculty of Science & Engineering.
    Andersson, Mats R.
    Polymer Technology, Department of Chemical and Biological Engineering, Chalmers University of Technology, Göteborg, Sweden.
    Inganäs, Olle
    Linköping University, Department of Physics, Chemistry and Biology, Biomolecular and Organic Electronics. Linköping University, The Institute of Technology.
    Universal modification of poor cathodes into good ones by a polymer interlayer for high performance reversed organic solar cells2014Manuscript (preprint) (Other academic)
    Abstract [en]

    In organic bulk-heterojunction solar cells, energy losses at the active layer/electrode interface are often observed. Modification of these interfaces with organic interlayers optimizes charge carrier injection and extraction and thus improves device performance. In this work, the effects of cathode modification by a conjugated polymer interlayer PFPA1 on the performance of reversed organic solar cells (substrate/cathode/active layer/transparent anode) based on different active material systems and different substrate electrodes are systematically investigated. A reduction of the work function irrespective of the substrate cathode used is observed upon the deposition of the PFPA1 interlayer; further related to an improved built-in electric field and open-circuit voltage. The amphiphilic character of the PFPA1 interlayer alters the surface energy of the substrate cathode, leading to the formation of a better active layer morphology aiding efficient exciton dissociation and photocurrent extraction in the modified solar cells. Hence, internal quantum efficiency is found significantly higher than that of their unmodified counterparts, while optically, the modified and unmodified solar cells are identical. Moreover, the deep HOMO of the PFPA1 interlayer improves the selectivity for all investigated substrate cathodes, thus enhancing the fill factor. We demonstrate a possibility of improving photovoltaic performance of reversed solar cells via a simple and universal interface modification and provide the basic guidelines for development and characterization of interface materials for organic solar cells in general.

  • 17.
    Ullah Khan, Zia
    et al.
    Linköping University, Department of Science and Technology, Physics and Electronics. Linköping University, Faculty of Science & Engineering.
    Bubnova, Olga
    Linköping University, Department of Science and Technology, Physics and Electronics. Linköping University, Faculty of Science & Engineering. Optoelectronics Group, Cavendish Laboratory, University of Cambridge, Cambridge, UK.
    Jafari, Mohammad Javad
    Linköping University, Department of Physics, Chemistry and Biology, Molecular Physics. Linköping University, Faculty of Science & Engineering.
    Brooke, Robert
    Linköping University, Faculty of Science & Engineering. Linköping University, Department of Science and Technology, Physics and Electronics. University of South Australia, Mawson Institute, Mawson Lakes 5095, Australia.
    Liu, Xianjie
    Linköping University, Department of Physics, Chemistry and Biology. Linköping University, Faculty of Science & Engineering.
    Gabrielsson, Roger
    Linköping University, Department of Science and Technology, Physics and Electronics. Linköping University, Faculty of Science & Engineering.
    Ederth, Thomas
    Linköping University, Department of Physics, Chemistry and Biology, Molecular Physics. Linköping University, Faculty of Science & Engineering.
    Evans, Drew R.
    University of South Australia, Mawson Institute, Australia.
    Andreasen, Jens W.
    Technical University of Denmark, Department of Energy Conversion and Storage, Roskilde, Denmark.
    Fahlman, Mats
    Linköping University, Department of Physics, Chemistry and Biology. Linköping University, Faculty of Science & Engineering.
    Crispin, Xavier
    Linköping University, Department of Science and Technology, Physics and Electronics. Linköping University, Faculty of Science & Engineering.
    Acido-basic control of the thermoelectric properties of poly(3,4-ethylenedioxythiophene)tosylate (PEDOT-Tos) thin films2015In: Journal of Materials Chemistry C, ISSN 2050-7526, E-ISSN 2050-7534, Vol. 3, p. 10616-10623Article in journal (Refereed)
    Abstract [en]

    PEDOT-Tos is one of the conducting polymers that displays the most promising thermoelectric properties. Until now, it has been utterly difficult to control all the synthesis parameters and the morphology governing the thermoelectric properties. To improve our understanding of this material, we study the variation in the thermoelectric properties by a simple acido-basic treatment. The emphasis of this study is to elucidate the chemical changes induced by acid (HCl) or base (NaOH) treatment in PEDOT-Tos thin films using various spectroscopic and structural techniques. We could identify changes in the nanoscale morphology due to anion exchange between tosylate and Cl- or OH-. But, we identified that changing the pH leads to a tuning of the oxidation level of the polymer, which can explain the changes in thermoelectric properties. Hence, a simple acid-base treatment allows finding the optimum for the power factor in PEDOT-Tos thin films.

  • 18.
    Wang, Suhao
    et al.
    Linköping University, Department of Science and Technology, Laboratory of Organic Electronics. Linköping University, Faculty of Science & Engineering.
    Fazzi, Daniele
    Univ Cologne, Germany.
    Puttisong, Yuttapoom
    Linköping University, Department of Physics, Chemistry and Biology, Biomolecular and Organic Electronics. Linköping University, Faculty of Science & Engineering.
    Jafari, Mohammad Javad
    Linköping University, Department of Physics, Chemistry and Biology, Molecular Physics. Linköping University, Faculty of Science & Engineering.
    Chen, Zhihua
    Flexterra Corp, IL 60077 USA.
    Ederth, Thomas
    Linköping University, Department of Physics, Chemistry and Biology, Molecular Physics. Linköping University, Faculty of Science & Engineering.
    Andreasen, Jens W.
    Tech Univ Denmark, Denmark.
    Chen, Weimin
    Linköping University, Department of Physics, Chemistry and Biology, Biomolecular and Organic Electronics. Linköping University, Faculty of Science & Engineering.
    Facchetti, Antonio
    Flexterra Corp, IL 60077 USA; Northwestern Univ, IL 60208 USA; Northwestern Univ, IL 60208 USA.
    Fabiano, Simone
    Linköping University, Department of Science and Technology, Physics and Electronics. Linköping University, Faculty of Science & Engineering.
    Effect of Backbone Regiochemistry on Conductivity, Charge Density, and Polaron Structure of n-Doped Donor-Acceptor Polymers2019In: Chemistry of Materials, ISSN 0897-4756, E-ISSN 1520-5002, Vol. 31, no 9, p. 3395-3406Article in journal (Refereed)
    Abstract [en]

    We investigated the influence of backbone regiochemistry on the conductivity, charge density, and polaron structure in the widely studied n-doped donor-acceptor polymer poly[N,N-bis(2-octyldodecyl)-1,4,5,8-naphthalenediimide-2,6-diyl]-alt-5,5-(2,2-bithiophene) [P-(NDI2OD-T2)]. In contrast to classic semicrystalline polymers such as poly(3-hexylthiophene) (P3HT), the regioirregular (RI) structure of the naphthalenediimide (NDI)-bithiophene (T2) backbone does not alter the intramolecular steric demand of the chain versus the regioregular (RR) polymer, yielding RI-P(NDI2OD-T2) with similar energetics and optical features as its RR counterpart. By combining the electrical, UV-vis/infrared, X-ray diffraction, and electron paramagnetic resonance data and density functional theory calculations, we quantitatively characterized the conductivity, aggregation, crystallinity, and charge density, and simulated the polaron structures, molecular vibrations, and spin density distribution of RR-/RI-P(NDI2OD-T2). Importantly, we observed that RI-P(NDI2OD-T2) can be doped to a greater extent compared to its RR counterpart. This finding is remarkable and contrasts benchmark P3HT, allowing us to uniquely study the role of regiochemistry on the charge-transport properties of n-doped donor-acceptor polymers.

  • 19.
    Wang, Yuming
    et al.
    Linköping University, Department of Physics, Chemistry and Biology, Biomolecular and Organic Electronics. Linköping University, Faculty of Science & Engineering. Nanjing Tech Univ, Peoples R China.
    Jafari, Mohammad Javad
    Linköping University, Department of Physics, Chemistry and Biology, Molecular Physics. Linköping University, Faculty of Science & Engineering.
    Wang, Nana
    Nanjing Tech Univ, Peoples R China.
    Qian, Deping
    Linköping University, Department of Physics, Chemistry and Biology, Biomolecular and Organic Electronics. Linköping University, Faculty of Science & Engineering.
    Zhang, Fengling
    Linköping University, Department of Physics, Chemistry and Biology, Biomolecular and Organic Electronics. Linköping University, Faculty of Science & Engineering.
    Ederth, Thomas
    Linköping University, Department of Physics, Chemistry and Biology, Molecular Physics. Linköping University, Faculty of Science & Engineering.
    Moons, Ellen
    Karlstad Univ, Sweden.
    Wang, Jianpu
    Nanjing Tech Univ, Peoples R China.
    Inganäs, Olle
    Linköping University, Department of Physics, Chemistry and Biology, Biomolecular and Organic Electronics. Linköping University, Faculty of Science & Engineering.
    Huang, Wei
    Nanjing Tech Univ, Peoples R China.
    Gao, Feng
    Linköping University, Department of Physics, Chemistry and Biology, Biomolecular and Organic Electronics. Linköping University, Faculty of Science & Engineering.
    Light-induced degradation of fullerenes in organic solar cells: a case study on TQ1:PC71BM2018In: Journal of Materials Chemistry A, ISSN 2050-7488, Vol. 6, no 25, p. 11884-11889Article in journal (Refereed)
    Abstract [en]

    The stability of organic solar cells (OSCs) is critical for practical applications of this emerging technology. Unfortunately, in spite of intensive investigations, the degradation mechanisms in OSCs have not been clearly understood yet. In this report, we employ a range of spectroscopic and transport measurements, coupled with drift-diffusion modelling, to investigate the light-induced degradation mechanisms of fullerene-based OSCs. We find that trap states formed in the fullerene phase under illumination play a critical role in the degradation of the open-circuit voltage (V-OC) in OSCs. Our results indicate that the degradation is intrinsic to the fullerenes in OSCs and that alternative acceptor materials are desired for the development of stable OSCs.

  • 20.
    Zhang, Qian
    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.
    Jiao, Fei
    Linköping University, Department of Science and Technology, Physics and 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.
    Jafari, Mohammad Javad
    Linköping University, Department of Physics, Chemistry and Biology, Molecular Physics. Linköping University, Faculty of Science & Engineering.
    Crispin, Xavier
    Linköping University, Department of Science and Technology, Physics and Electronics. Linköping University, Faculty of Science & Engineering.
    Ederth, Thomas
    Linköping University, Department of Physics, Chemistry and Biology, Molecular Physics. 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.
    Ground-state charge transfer for NIR absorption with donor/acceptor molecules: interactions mediated via energetics and orbital symmetries2017In: Journal of Materials Chemistry C, ISSN 2050-7526, E-ISSN 2050-7534, Vol. 5, no 2, p. 275-281Article in journal (Refereed)
    Abstract [en]

    The interactions between electron donors (D) and acceptors (A) of organic semiconducting molecules are of great interest to organic electronics, e.g. electrical doping of organic semiconductors (OSCs), photo-generation of charges in organic solar cells, and light-emitting/detecting devices based on OSCs. A blend of D/A OSC is typically characterized by weak van der Waals interactions or integer charge transfer (ICT) between neighboring D/A molecules. In between these two scenarios of physical blends and ICT complexes, orbital hybridization between adjacent D/A molecules serves as a third alternative, characterized by an in situ formation of a ground state complex featuring partial charge transfer between participating donor and acceptor molecules. In this work is presented a comprehensive experimental study on partial charge-transfer complex (CPX) formed via orbital hybridization. Thiophenes and phthalocyanines are used as electron donors, while acceptor molecules of different geometries and electron affinities are employed with the aim to clarify how orbital symmetry, energy level alignment and steric hindrance affect orbital hybridization and subsequent tuning of the optical band-gap into the near infrared (NIR) region.

1 - 20 of 20
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