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  • 1.
    Andersson Ersman, Peter
    et al.
    Acreo AB, Norrköping, Sweden .
    Kawahara, Jun
    Linköping University, Department of Science and Technology. Linköping University, The Institute of Technology.
    Berggren, Magnus
    Linköping University, Department of Science and Technology, Physics and Electronics. Linköping University, The Institute of Technology.
    Printed passive matrix addressed electrochromic displays2013In: Organic electronics, ISSN 1566-1199, E-ISSN 1878-5530, Vol. 14, no 12, p. 3371-3378Article in journal (Refereed)
    Abstract [en]

    Flexible displays are attracting considerable attention as a visual interface for applications such as in electronic papers and paper electronics. Passive or active matrix-addressing of individual pixels require display elements that include proper signal addressability, which is typically provided by non-linear device characteristics or by incorporating transistors into each pixel, respectively. Including such additional devices into each pixel element make manufacturing of flexible displays using adequate printing techniques very hard or even impossible. Here, we report all-printed passive matrix-addressed electrochromic displays (PMAD) that can be manufactured using standard printing tools. Poly(3,4-ethylenedioxythiophene) doped with poly(styrenesulfonate) (PEDOT:PSS) serves as the conducting and electrochromic pixel electrodes and carbon paste is used as the pixel counter electrodes. These electrodes sandwich self-assembled layers of a polyelectrolyte that are confined to desired pixel areas via surface energy patterning. The particular choice of materials results in a desired current vs. voltage threshold that enables addressability in electronic cross-point matrices. The resulting PMAD, built up from a robust architecture including only few different materials, operates at less than 3 V, exhibits high color switch contrast without any cross-talk promises for high-volume and low-cost production of flexible displays using reel-to-reel printing tools on plastic foils and on paper.

  • 2.
    Andersson Ersman, Peter
    et al.
    Acreo AB, Sweden.
    Nilsson, David
    Acreo AB, Sweden.
    Kawahara, Jun
    Linköping University, Department of Science and Technology. Linköping University, The Institute of Technology. Acreo AB, Sweden .
    Gustafsson, Göran
    Acreo AB, Sweden.
    Berggren, Magnus
    Linköping University, Department of Science and Technology, Physics and Electronics. Linköping University, The Institute of Technology.
    Fast-switching all-printed organic electrochemical transistors2013In: Organic electronics, ISSN 1566-1199, E-ISSN 1878-5530, Vol. 14, no 5, p. 1276-1280Article in journal (Refereed)
    Abstract [en]

    Symmetric and fast (∼5 ms) on-to-off and off-to-on drain current switching characteristics have been obtained in screen printed organic electrochemical transistors (OECTs) including PEDOT:PSS (poly(3,4-ethylenedioxythiophene) doped with poly(styrene sulfonic acid)) as the active transistor channel material. Improvement of the drain current switching characteristics is made possible by including a carbon conductor layer on top of PEDOT:PSS at the drain electrode that is in direct contact with both the channel and the electrolyte of the OECT. This carbon conductor layer suppresses the effects from a reduction front that is generated in these PEDOT:PSS-based OECTs. In the off-state of these devices this reduction front slowly migrate laterally into the PEDOT:PSS drain electrode, which make off-to-on switching slow. The OECT including carbon electrodes was manufactured using only standard printing process steps and may pave the way for fully integrated organic electronic systems that operate at low voltages for applications such as logic circuits, sensors and active matrix addressed displays.

  • 3.
    Andersson, Lars Mattias
    et al.
    Linköping University, Department of Physics, Chemistry and Biology, Biomolecular and Organic Electronics . Linköping University, The Institute of Technology.
    Inganäs, Olle
    Linköping University, Department of Physics, Chemistry and Biology, Biomolecular and Organic Electronics . Linköping University, The Institute of Technology.
    Non-equilibrium effects on electronic transport in organic field effect transistors2007In: Organic electronics, ISSN 1566-1199, E-ISSN 1878-5530, Vol. 8, no 4, p. 423-430Article in journal (Refereed)
    Abstract [en]

    Non-ideal behavior in organic field effect transistors, in particular threshold voltage drift and light sensitivity, is argued to be due to intrinsic carrier dynamics. The discussion is based on the theory for hopping transport within a Gaussian density of states. Carrier concentration is shown to be of fundamental importance, and the time required to reach equilibrium at different bias is responsible for device behavior, with implications for mobility evaluation. Experimental results from various conjugated polymers in a field effect transistor illustrate the theory.

  • 4.
    Andersson, Mattias
    et al.
    Linköping University, Department of Physics, Chemistry and Biology, Biomolecular and Organic Electronics. Linköping University, The Institute of Technology.
    Hsu, Yu-Te
    Linköping University, Department of Physics, Chemistry and Biology. Linköping University, Faculty of Health Sciences.
    Vandewal, Koen
    Linköping University, Department of Physics, Chemistry and Biology, Biomolecular and Organic Electronics. Linköping University, Faculty of Science & Engineering.
    Sieval, Alexander B
    Solenne BV, Groningen, The Netherlands.
    Andersson, Mats R.
    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.
    Mixed C60/C70 based fullerene acceptors in polymer bulk-heterojunction solar cells2012In: Organic electronics, ISSN 1566-1199, E-ISSN 1878-5530, Vol. 13, no 12, p. 2856-2864Article in journal (Refereed)
    Abstract [en]

    Different mixtures of identically substituted C60 and C70 based fullerens have been used as acceptors in three polymer: fullerene systems that strongly express various performance limiting aspects of bulk heterojunction solar cells. Results are correlated with, and discussed in terms of e.g. morphology, charge separation, and charge transport. In these systems, there appears to be no relevant differences in either mobility or energy level positions between the identically substituted C60 and C70 based fullerenes tested. Examples of how fullerene mixtures influence the nano-morphology of the active layer are given. An upper limit to the open circuit voltage that can be obtained with fullerenes is also suggested.

  • 5.
    Andersson, Mattias
    et al.
    Linköping University, The Institute of Technology. Linköping University, Department of Physics, Chemistry and Biology, Biomolecular and Organic Electronics.
    Osikowicz, Wojciech
    Linköping University, The Institute of Technology. Linköping University, Department of Physics, Chemistry and Biology, Surface Physics and Chemistry.
    Jakobsson, Fredrik L.E.
    Linköping University, Department of Science and Technology. Linköping University, The Institute of Technology.
    Berggren, Magnus
    Linköping University, The Institute of Technology. Linköping University, Department of Science and Technology.
    Lindgren, L.
    Polymer Chemistry, Department of Materials and Surface Chemistry, Chalmers University of Technology, SE-412 96 Gothenburg, Sweden.
    Andersson, M.R.
    Polymer Chemistry, Department of Materials and Surface Chemistry, Chalmers University of Technology, SE-412 96 Gothenburg, Sweden.
    Inganäs, Olle
    Linköping University, The Institute of Technology. Linköping University, Department of Physics, Chemistry and Biology, Biomolecular and Organic Electronics.
    Intrinsic and extrinsic influences on the temperature dependence of mobility in conjugated polymers2008In: Organic electronics, ISSN 1566-1199, E-ISSN 1878-5530, Vol. 9, no 5, p. 569-574Article in journal (Refereed)
    Abstract [en]

    The temperature dependence of charge carrier mobility in conjugated polymers and their blends with fullerenes is investigated with different electrical methods, through field effect transistor (FET), space charge limited current (SCLC) and charge extraction (CELIV) measurements. Simple models, such as the Gaussian disorder model (GDM), are shown to accurately predict the temperature behavior, and a good correlation between the different measurement methods is obtained. Inconsistent charge carrier concentrations in the modeling are explained through intrinsic non-equilibrium effects, and are responsible for the limited applicability of existing numerical models. A severe extrinsic influence from water in FETs with a hydrophilic insulator interface is also demonstrated. The presence of water leads to a significant overestimate of the disorder in the materials from measurements close to room temperature and erratic behavior in the 150-350 K range. To circumvent this problem it is shown to be necessary to measure under ultra high vacuum (UHV) conditions. © 2008 Elsevier B.V. All rights reserved.

  • 6.
    Bernard, L.
    et al.
    Empa, Switzerland; Eindhoven University of Technology, Netherlands.
    Khikhlovskyi, V.
    TNO Dutch Org Appl Science Research, Netherlands.
    van Breemen, A.
    TNO Dutch Org Appl Science Research, Netherlands.
    Michels, J. J.
    Max Planck Institute Polymer Research, Germany.
    Janssen, R.
    Eindhoven University of Technology, Netherlands.
    Kemerink, Martijn
    Linköping University, Department of Physics, Chemistry and Biology, Complex Materials and Devices. Linköping University, Faculty of Science & Engineering. Eindhoven University of Technology, Netherlands.
    Gelinck, G.
    Eindhoven University of Technology, Netherlands; TNO Dutch Org Appl Science Research, Netherlands.
    Pilet, N.
    Paul Scherrer Institute, Switzerland.
    Study of the morphology of organic ferroelectric diodes with combined scanning force and scanning transmission X-ray microscopy2018In: Organic electronics, ISSN 1566-1199, E-ISSN 1878-5530, Vol. 53, p. 242-248Article in journal (Refereed)
    Abstract [en]

    Organic ferroelectric diodes attract increasing interest as they combine non-destructive data read-out and low cost fabrication, two requirements in the development of novel non-volatile memory elements. The macroscopic electrical characteristics and performances of such devices strongly depend on their structural properties. Various studies of their global microscopic morphology have already been reported. Here, a multi-technique approach including different scanning force and X-ray microscopies permitted to reveal and locally study nanometer-scale unexpected sub-structures within a P(VDF-TrFE):F8BT ferroelectric diode. The strong impact of these structures on the local polarizability of the ferroelectric is shown. Two alternative fabrication methods are proposed that prevent the formation of these structures and demonstrate improved macroscopic device performances such as endurance and ON/OFF ratio.

    The full text will be freely available from 2019-12-05 16:28
  • 7.
    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.

  • 8.
    Brocks, Geert
    et al.
    University of Twente, Netherlands.
    Cakir, Deniz
    University of Twente, Netherlands.
    Bokdam, Menno
    University of Twente, Netherlands.
    de Jong, Michel P
    University of Twente, Netherlands .
    Fahlman, Mats
    Linköping University, Department of Physics, Chemistry and Biology, Surface Physics and Chemistry. Linköping University, The Institute of Technology.
    Charge equilibration and potential steps in organic semiconductor multilayers2012In: Organic electronics, ISSN 1566-1199, E-ISSN 1878-5530, Vol. 13, no 10, p. 1793-1801Article in journal (Refereed)
    Abstract [en]

    Substantial potential steps similar to 0.5 eV are frequently observed in organic multilayers of donor and acceptor molecules. Often such potential steps depend on the order in which the individual layers are deposited, or on which substrate they are deposited. In this paper we outline a model for these potential steps, based upon integer charge transfer between donors and acceptors, charge equilibration across the multilayer, and simple electrostatics. Each donor, acceptor, or substrate material is characterized by a pinning level, and the potential profile can be deduced from the sequential order of the layers, and the differences between their pinning levels. For particular orderings we predict that intrinsic potential differences lead to electric fields across individual layers, which may falsely be interpreted as band bending.

  • 9.
    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.

  • 10.
    Charrier, D. S. H.
    et al.
    Eindhoven University of Technology, Netherlands.
    de Vries, T.
    Eindhoven University of Technology, Netherlands.
    Mathijssen, S. G. J.
    Eindhoven University of Technology, Netherlands; Philips Research Labs, Netherlands.
    Geluk, E. -J.
    Eindhoven University of Technology, Netherlands.
    Smits, E. C. P.
    Philips Research Labs, Netherlands; University of Groningen, Netherlands.
    Kemerink, M.
    Eindhoven University of Technology, Netherlands.
    Janssen, R. A. J.
    Eindhoven University of Technology, Netherlands.
    Bimolecular recombination in ambipolar organic field effect transistors2009In: Organic electronics, ISSN 1566-1199, E-ISSN 1878-5530, Vol. 10, no 5, p. 994-997Article in journal (Refereed)
    Abstract [en]

    In ambipolar organic field effect transistors (OFET) the shape of the channel potential is intimately related to the recombination zone width W, and hence to the electron-hole recombination strength. Experimentally, the recombination profile can be assessed by scanning Kelvin probe microscopy (SKPM). However, surface potentials as measured by SKPM are distorted due to spurious capacitive couplings. Here, we present a (de)convolution method with an experimentally calibrated transfer function to reconstruct the actual surface potential from a measured SKPM response and vice versa. Using this scheme, we find W = 0.5 mu m for a nickel dithiolene OFET, which translates into a recombination rate that is two orders of magnitude below the value expected for Langevin recombination. (C) 2009 Elsevier B.V. All rights reserved.

  • 11.
    Chen, Zhuoying
    et al.
    University of Cambridge, England.
    Fang, Junfeng
    University of Cambridge, England.
    Gao, Feng
    Linköping University, Department of Physics, Chemistry and Biology, Biomolecular and Organic Electronics. Linköping University, The Institute of Technology.
    Brenner, Thomas J. K.
    University of Cambridge, England.
    Banger, Kulbinder K.
    University of Cambridge, England.
    Wang, Xingzhu
    University of Cambridge, England.
    Huck, Wilhelm T. S.
    Radboud University of Nijmegen, Netherlands; University of Cambridge, England.
    Sirringhaus, Henning
    University of Cambridge, England.
    Enhanced charge transport by incorporating additional thiophene units in the poly(fluorene-thienyl-benzothiadiazole) polymer2011In: Organic electronics, ISSN 1566-1199, E-ISSN 1878-5530, Vol. 12, no 3, p. 461-471Article in journal (Refereed)
    Abstract [en]

    We report a comparative study of optical properties, structure and morphology, field-effect transistor (FET) and solar cell performance between poly(4-(3,4-dihexyl-2,2-bithiophen-5-yl)-7-(5-(9,9-dioctyl-9H-fluoren-2-yl)-3,4-dihexyl-2,2-bithiophen-5-yl)benzo[c][1,2,5]-thiadiazole) (F8TTBTT), and its predecessor poly((9,9-dioctylfluorene)-2,7-diyl-alt[4,7-bis(3-hexylthien-5-yl)-2,1,3-benzothiadiazole]-2,2 -diyl) (F8TBT). Compared to F8TBT, F8TTBTT has two more thiophene units incorporated in its monomer structure. Such a modification leads to a reduced optical band gap, improved charge injection and significantly enhanced ambipolar field-effect mobilities reaching 5 x 10 (2) cm(2) V (1) s (1) for holes and 4 x 10 (3) cm(2) V (1) s (1) for electrons. The enhanced carrier mobilities are most likely a result of an increased backbone planarization and interchain interaction. As a consequence of ambipolar transport, light-emission was observed from the transistor channel during operation. The reduced band gap and improved charge transport make F8TTBTT an interesting candidate also for solar cell applications. Unoptimized solar cells based on F8TTBTT: PCBM blends were found to exhibit power conversion efficiency under AM 1.5 illumination of similar to 1.54%. (C) 2011 Published by Elsevier B.V.

  • 12.
    Cotrone, Serafina
    et al.
    Università di Bari “Aldo Moro”.
    Ambrico, Marianna
    CNR-IMIP.
    Toss, Henrik
    Linköping University, Department of Science and Technology. Linköping University, The Institute of Technology.
    Angione, M. Daniela
    Università di Bari “Aldo Moro”.
    Magliulo, Maria
    Università di Bari “Aldo Moro”.
    Mallardi, Antonia
    CNR-IPCF.
    Berggren, Magnus
    Linköping University, Department of Science and Technology, Physics and Electronics. Linköping University, The Institute of Technology.
    Palazzo, Gerardo
    Università di Bari “Aldo Moro”.
    Horowitz, Gilles
    University Paris Diderot.
    Ligonzo, Teresa
    Università di Bari “Aldo Moro”.
    Torsi, Luisa
    Università di Bari “Aldo Moro”.
    Phospholipid film in electrolyte-gated organic field-effect transistors2012In: Organic electronics, ISSN 1566-1199, E-ISSN 1878-5530, Vol. 13, no 4, p. 638-644Article in journal (Refereed)
    Abstract [en]

    A totally innovative electrolyte-gated field effect transistor, embedding a phospholipid film at the interface between the organic semiconductor and the gating solution, is described. The electronic properties of OFETs including a phospholipid film are studied in both pure water and in an electrolyte solution and compared to those of an OFET with the organic semiconductor directly in contact with the gating solution. In addition, to investigate the role of the lipid layers in the charge polarization process and quantify the field-effect mobility, impedance spectroscopy was employed. The results indicate that the integration of the biological film minimizes the penetration of ions into the organic semiconductor thus leading to a capacitive operational mode as opposed to an electrochemical one. The OFETs operate at low voltages with a field-effect mobility in the 10−3 cm2 V−1 s−1 range and an on/off current ratio of 103. This achievement opens perspectives to the development of FET biosensors potentially capable to operate in direct contact with physiological fluids.

  • 13.
    Felekidis, Nikolaos
    et al.
    Linköping University, Department of Physics, Chemistry and Biology, Complex Materials and Devices. Linköping University, Faculty of Science & Engineering.
    Melianas, Armantas
    Stanford Univ, CA 94305 USA.
    Kemerink, Martijn
    Linköping University, Department of Physics, Chemistry and Biology, Complex Materials and Devices. Linköping University, Faculty of Science & Engineering.
    Automated open-source software for charge transport analysis in single-carrier organic semiconductor diodes2018In: Organic electronics, ISSN 1566-1199, E-ISSN 1878-5530, Vol. 61, p. 318-328Article, review/survey (Refereed)
    Abstract [en]

    Organic electronics is an emerging technology with numerous applications in which the active layer is composed of an organic semiconductor (OSC) or blends of multiple OSC. One of the key performance parameters for such devices is the charge carrier mobility which can be evaluated by different measurement techniques. Here, we review different formalisms for extraction and analysis of hole mobilities from temperature-dependent space-charge limited conductivity (SCLC) measurements for pristine OSC as well as for binary and ternary blends as used in e.g. photovoltaic applications. The model is also applicable to n-type materials. Possible sources of measurement errors, such as the presence of traps and series resistance, are discussed. We show that by a simple method of selecting a proper experimental data range these errors can be avoided. The Murgatroyd-Gill analytical model in combination with the Gaussian Disorder Model is used to extract zero-field hole mobilities as well as estimates of the Gaussian energetic disorder in the HOMO level from experimental data. The resulting mobilities are in excellent agreement with those found from more elaborate fits to a full drift-diffusion model that includes a temperature, field and density dependent charge carrier mobility; the same holds for the Gaussian disorder of pure materials and blends with low fullerene concentration. The zero-field mobilities are also analyzed according to an Arrhenius model that was previously argued to reveal a universal mobility law; for most -but not all- material systems in the present work this framework gave an equally good fit to the experimental data as the other models. An automated fitting freeware, incorporating the different models, is made openly available for download and minimizes error, user input and SCLC data analysis time; e.g. SCLC current-voltage curves at several different temperatures can be globally fitted in a few seconds.

    The full text will be freely available from 2020-06-15 17:03
  • 14.
    Guo, Xuewen
    et al.
    East China Normal Univ, Peoples R China.
    Li, Danqin
    East China Normal Univ, Peoples R China.
    Zhang, Yuexing
    Soochow Univ, Peoples R China.
    Jan, Ming
    Shanghai Jiao Tong Univ, Peoples R China.
    Xu, Jinqiu
    Shanghai Jiao Tong Univ, Peoples R China.
    Wang, Zhiquan
    East China Normal Univ, Peoples R China.
    Li, Bo
    East China Normal Univ, Peoples R China.
    Xiong, Shaobing
    East China Normal Univ, Peoples R China.
    Li, Yanqing
    Soochow Univ, Peoples R China.
    Liu, Feng
    Shanghai Jiao Tong Univ, Peoples R China.
    Tang, Jianxin
    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.
    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; Shanxi Univ, Peoples R China; Soochow Univ, Peoples R China.
    Understanding the effect of N2200 on performance of J71: ITIC bulk heterojunction in ternary non-fullerene solar cells2019In: Organic electronics, ISSN 1566-1199, E-ISSN 1878-5530, Vol. 71, p. 65-71Article in journal (Refereed)
    Abstract [en]

    None-fullerene solar cells with ternary architecture have attracted much attention because it is an effective approach for boosting the device power conversion efficiency. Here, the crystalline polymer N2200 as the third component is integrated into J71: ITIC bulk heterojunction. A series of characterizations indicate that N2200 could increase photo-harvesting, balanced hole and electron mobilities, enhanced exciton dissociation, and suppressed charge recombination, which result in the comprehensive improvement of open circuit voltage, short circuit current and fill factor in the device. Moreover, after introduction of N2200, the morphology of the ternary active layer is optimized, and the film crystallinity is improved. This work demonstrates that adding a small quantity of high crystallization acceptor into non-fullerene donor: acceptor mixture is a promising strategy toward developing high-performance organic solar cells.

  • 15.
    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.

  • 16.
    Isaksson, Joakim
    et al.
    Linköping University, Department of Science and Technology. Linköping University, The Institute of Technology.
    Nilsson, David
    Linköping University, Department of Science and Technology. Linköping University, The Institute of Technology.
    Kjäll, Peter
    Karolinska Institutet.
    Robinson, Nathaniel
    Linköping University, The Institute of Technology. Linköping University, Department of Physics, Chemistry and Biology, Surface Physics and Chemistry.
    Richter-Dahlfors, Agneta
    Karolinska Institutet.
    Berggren, Magnus
    Linköping University, Department of Science and Technology. Linköping University, The Institute of Technology.
    Electronically Controlled pH Gradients and Proton Oscillations2008In: Organic electronics, ISSN 1566-1199, E-ISSN 1878-5530, Vol. 9, no 3, p. 303-309Article in journal (Refereed)
    Abstract [en]

    An organic electronic ion pump, including poly(3,4-ethylenedioxythiophene) as the active material has been used to electronically control the transport of protons between two electrolytes and to change the pH of the target solution from 7 to 3 in a few minutes. The number of transported protons equals the time-integrated current between the two addressing electrodes. If no voltage is applied the leakage due to diffusion is not detectable, which indicates an overall proton delivery on/off ratio exceeding 1000. Locally, the pH drop can be even larger and the relationship between the proton delivery rate of the pump and proton diffusion in the electrolyte forms pH gradients. If the device is instead addressed with short pulses, local pH oscillations are created. The transport of protons presented here can be extended to other small sized ions, which in combination with the biocompatibility of the delivery surface make the device promising for cell communication studies and lab-on-a-chip applications.

  • 17.
    Jakobsson, Fredrik L. E.
    et al.
    Linköping University, Department of Science and Technology. Linköping University, The Institute of Technology.
    Crispin, Xavier
    Linköping University, Department of Science and Technology. Linköping University, The Institute of Technology.
    Berggren, Magnus
    Linköping University, Department of Science and Technology. Linköping University, The Institute of Technology.
    Prediction of the current versus voltage behavior of devices based on organic semiconductor host-guest systems2009In: Organic electronics, ISSN 1566-1199, E-ISSN 1878-5530, Vol. 10, no 1, p. 95-106Article in journal (Refereed)
    Abstract [en]

    Organic semiconductor blends are commonly used in organic based (opto-)electronic devices. They are composed of two types of (macro-) molecules, referredto as the guest and host. To achieve optimum device operation, the chemicalnature, electronic structure, molecular order and the relative concentration of theguests and host are crucial. Here, we present simulation results of the currentdensity versus the voltage (J-V) behavior of a two-terminal device based on avariable-range hopping model in which the electronic states of the guest and hostare represented by two Gaussian distributions. The J-V behavior is investigatedfor various energetic mismatches between guest and host states, widths of thedistribution as well as the guest concentration. Finally, a simple tool enablingeasy prediction of the J-V behavior of organic host-guest diodes is derived.

  • 18.
    Janssen, FJJ
    et al.
    Eindhoven University of Technology, Netherlands.
    Sturm, JM
    Eindhoven University of Technology, Netherlands.
    van der Gon, AWD
    Eindhoven University of Technology, Netherlands.
    van IJzendoorn, LJ
    Eindhoven University of Technology, Netherlands.
    Kemerink, Martijn
    Eindhoven University of Technology, Netherlands.
    Schoo, HFM
    Eindhoven University of Technology, Netherlands.
    de Voigt, MJA
    Eindhoven University of Technology, Netherlands.
    Brongersma, HH
    Eindhoven University of Technology, Netherlands.
    Interface instabilities in polymer light emitting diodes due to annealing2003In: Organic electronics, ISSN 1566-1199, E-ISSN 1878-5530, Vol. 4, no 4, p. 209-218Article in journal (Refereed)
    Abstract [en]

    In polymer light emitting diodes (PLEDS) with an (ITO/PPV/Ca) structure we observed a significant reduction of both the current and the light output at constant voltage after heat treatment for only 30 min at 65 degreesC. Electroluminescence spectroscopy experiments showed that the shape as well as the amplitude of the spectra were changed. The reduction of current and light output was investigated by measuring I-V and E-V (current-voltage and brightness-voltage) characteristics of PLEDs, I-V characteristics of single carrier devices, and by performing low energy ion scattering and X-ray photoelectron spectroscopy experiments on the Ca/PPV interface. It was concluded that the current and light output reduction could be ascribed to the degradation of the Ca/PPV and the ITO/PPV interfaces. The degradation of the ITO/PPV interface resulted in a reduction of the zero field hole mobility and a small increase of the field dependence of the mobility. The degradation of the Ca/PPV interface, probably by diffusion of calcium into the PPV, resulted in carrier traps and quenching sites, which influenced the field dependent electron mobility. (C) 2003 Elsevier B.V. All rights reserved.

  • 19.
    Jespersen, Kim G
    et al.
    Chemical Physics Kemicentrum.
    Zhang, Fengling
    Linköping University, Department of Physics, Chemistry and Biology, Biomolecular and Organic Electronics . Linköping University, The Institute of Technology.
    Gadisa, Abay
    Linköping University, Department of Physics, Chemistry and Biology.
    Sundström, Villy
    Chemical Physics Kemicentrum.
    Yartsev, Arkady
    Chemical Physics Kemicentrum.
    Inganäs, Olle
    Linköping University, The Institute of Technology. Linköping University, Department of Physics, Chemistry and Biology, Biomolecular and Organic Electronics .
    Charge formation and transport in bulk-heterojunction solar cells based on alternating polyfluorene copolymers blended with fullerenes2006In: Organic electronics, ISSN 1566-1199, E-ISSN 1878-5530, Vol. 7, p. 235-242Article in journal (Refereed)
  • 20.
    Kanbur, Yasin
    et al.
    Johannes Kepler Univ Linz, Austria; Karabuk Univ, Turkey.
    Coskun, Halime
    Johannes Kepler Univ Linz, Austria.
    Glowacki, Eric
    Linköping University, Department of Science and Technology, Physics and Electronics. Linköping University, Faculty of Science & Engineering. Johannes Kepler Univ Linz, Austria.
    Irimia-Vladu, Mihai
    Joanneum Res Forschungsgesell mbH, Austria.
    Sariciftci, Niyazi Serdar
    Johannes Kepler Univ Linz, Austria.
    Yumusak, Cigdem
    Johannes Kepler Univ Linz, Austria.
    High temperature-stability of organic thin-film transistors based on quinacridone pigments2019In: Organic electronics, ISSN 1566-1199, E-ISSN 1878-5530, Vol. 66, p. 53-57Article in journal (Refereed)
    Abstract [en]

    Robust organic thin-film transistors (OTFTs) with high temperature stability allow device integration with mass production methods like thermoforming and injection molding, and enable operation in extreme environment applications. Herein we elaborate a series of materials to make suitable gate dielectric and active semiconductor layers for high temperature stable OTFTs. We employ an anodized aluminum oxide layer passivated with cross-linked low-density polyethylene (LD-PE) to form a temperature-stable gate capacitor. As the semiconductor, we use quinacridone, an industrial organic colorant pigment produced on a mass scale. Evaporated MoOx/Ag source and drain electrodes complete the devices. Here we evaluate the performance of the OTFTs healing them in air from 100 degrees C in 25 degrees C increments up to 225 degrees C, holding each temperature for a period of 30 minutes. We find large differences in stability between quinacridone and its dimethylated derivative, with the former showing the best performance with only a factor of 2 decline in mobility after healing at 225 degrees C, and unaffected on/off ratio and threshold voltage. The approach presented here shows how industriallys calable fabrication of thermally robust OTFTs can be rationalized.

  • 21.
    Kawahara, Jun
    et al.
    Linköping University, Department of Science and Technology. Linköping University, The Institute of Technology.
    Andersson Ersman, Peter
    Acreo AB.
    Engquist, Isak
    Linköping University, Department of Science and Technology. Linköping University, The Institute of Technology.
    Berggren, Magnus
    Linköping University, Department of Science and Technology. Linköping University, The Institute of Technology.
    Improving the color switch contrast in PEDOT:PSS-based electrochromic displays2012In: Organic electronics, ISSN 1566-1199, E-ISSN 1878-5530, Vol. 13, no 3, p. 469-474Article in journal (Refereed)
    Abstract [en]

    Poly(3,4-ethylenedioxythiophene) chemically doped with poly(styrene sulfonic acid) (PEDOT:PSS) is a material system commonly used as a conductive and transparent coating in several important electronic applications. The material is also electrochemically active and exhibits electrochromic (EC) properties making it suitable as the active element in EC display applications. In this work uniformly coated PEDOT:PSS layers were used both as the pixel electrode and as the counter electrode in EC display components. The pixel and counter electrodes were separated by a whitish opaque and water-based polyelectrolyte and the thicknesses of the two EC layers were varied independently in order to optimize the color contrast of the display element. A color contrast (ΔE, CIE Lab color space) exceeding 40 was obtained with maintained relatively short switching time at an operational voltage less than 2 V.

  • 22.
    Kawahara, Jun
    et al.
    Linköping University, Department of Science and Technology. Linköping University, The Institute of Technology. Acreo Swedish ICT AB, Sweden and Lintec Corporation, Japan.
    Andersson Ersman, Peter
    Acreo Swedish ICT AB, Sweden.
    Wang, Xin
    Acreo Swedish ICT AB, Sweden.
    Gustafsson, Göran
    Acreo Swedish ICT AB, Sweden.
    Granberg, Hjalmar
    Innventia AB, Sweden.
    Berggren, Magnus
    Linköping University, Department of Science and Technology. Linköping University, The Institute of Technology.
    Reconfigurable sticker label electronics manufactured from nanofibrillated cellulose-based self-adhesive organic electronic materials2013In: Organic electronics, ISSN 1566-1199, E-ISSN 1878-5530, Vol. 14, no 11, p. 3061-3069Article in journal (Refereed)
    Abstract [en]

    Low voltage operated electrochemical devices can be produced from electrically conducting polymers and polyelectrolytes. Here, we report how such polymers and polyelectrolytes can be cast together with nanofibrillated cellulose (NFC) derived from wood. The resulting films, which carry ionic or electronic functionalities, are all-organic, disposable, light-weight, flexible, self-adhesive, elastic and self-supporting. The mechanical and self-adhesive properties of the films enable simple and flexible electronic systems by assembling the films into various kinds of components using a "cut and stick" method. Additionally, the self-adhesive surfaces provide a new concept that not only allows for simplified system integration of printed electronic components, but also allows for a unique possibility to detach and reconfigure one or several subcomponents by a "peel and stick" method to create yet another device configuration. This is demonstrated by a stack of two films that first served as the electrolyte layer and the pixel electrode of an electrochromic display, which then was detached from each other and transferred to another configuration, thus becoming the electrolyte and gate electrode of an electrochemical transistor. Further, smart pixels, consisting of the combination of one electrochromic pixel and one electrochemical transistor, have successfully been manufactured with the NFC-hybridized materials. The concept of system reconfiguration was further explored by that a pixel electrode charged to its colored state could be detached and then integrated on top of a transistor channel. This resulted in spontaneous discharging and associated current modulation of the transistor channel without applying any additional gate voltage. Our peel and stick approach promises for novel reconfigurable electronic devices, e. g. in sensor, label and security applications.

  • 23.
    Kemerink, Martijn
    et al.
    Eindhoven University of Technology, Netherlands.
    Asadi, Kamal
    University of Groningen, Netherlands; Philips Research Labs, Netherlands.
    Blom, Paul W. M.
    University of Groningen, Netherlands; Holst Centre, Netherlands.
    de Leeuw, Dago M.
    University of Groningen, Netherlands; Philips Research Labs, Netherlands.
    The operational mechanism of ferroelectric-driven organic resistive switches2012In: Organic electronics, ISSN 1566-1199, E-ISSN 1878-5530, Vol. 13, no 1, p. 147-152Article in journal (Refereed)
    Abstract [en]

    The availability of a reliable memory element is crucial for the fabrication of plastic logic circuits. We use numerical simulations to show that the switching mechanism of ferroelectric-driven organic resistive switches is the stray field of the polarized ferroelectric phase. The stray field modulates the charge injection from a metallic electrode into the organic semiconductor, switching the diode from injection limited to space charge limited. The modeling rationalizes the previously observed exponential dependence of the on/off ratio on injection barrier height. We find a lower limit of about 50 nm for the feature size that can be used in a crossbar array, translating into a rewritable memory with an information density of the order of 1 Gb/cm(2). (C) 2011 Elsevier B. V. All rights reserved.

  • 24.
    Kergoat, Loig
    et al.
    Linköping University, Department of Science and Technology, Physics and Electronics. Linköping University, The Institute of Technology.
    Piro, Benoît
    Université Paris Diderot, France.
    Berggren, Magnus
    Linköping University, Department of Science and Technology, Physics and Electronics. Linköping University, The Institute of Technology.
    Pham, Minh-Chau
    Université Paris Diderot, France.
    Yassar, Abderrahim
    Ecole Polytechnique, Palaiseau, France.
    Horowitz, Gilles
    Université Paris Diderot, France.
    DNA detection with a water-gated organic field-effect transistor2012In: Organic electronics, ISSN 1566-1199, E-ISSN 1878-5530, Vol. 13, no 1, p. 1-6Article in journal (Refereed)
    Abstract [en]

    A DNA sensor based on a water-gated organic field-effect transistor is described. The semiconductor is poly [3-(5-carboxypentyl)thiophene-2,5-diyl] onto which DNA probes are covalently grafted via NHS/EDC chemistry. Clear changes in the output characteristic of the device are observed upon DNA immobilization and after DNA hybridization. Experimental data point out the importance of the electrolyte Debye length that can screen negative DNA charges and impede transduction. For this reason, deionized water was used in order to increase the Debye length up to several hundreds of nanometers. In this case, a decrease in the off current was observed upon hybridization, whereas no significant change occurred when using saline solutions.

  • 25.
    Khikhlovskyi, Vsevolod
    et al.
    Eindhoven University of Technology, Netherlands; TNO Dutch Org Appl Science Research, Netherlands.
    Gorbunov, Andrey V.
    Eindhoven University of Technology, Netherlands.
    van Breemen, Albert J. J. M.
    TNO Dutch Org Appl Science Research, Netherlands.
    Janssen, Rene A. J.
    Eindhoven University of Technology, Netherlands.
    Gelinck, Gerwin H.
    TNO Dutch Org Appl Science Research, Netherlands.
    Kemerink, Martijn
    Eindhoven University of Technology, Netherlands.
    Multi-bit organic ferroelectric memory2013In: Organic electronics, ISSN 1566-1199, E-ISSN 1878-5530, Vol. 14, no 12, p. 3399-3405Article in journal (Refereed)
    Abstract [en]

    Storage of multiple bits per element is a promising alternative to miniaturization for increasing the information data density in memories. Here we introduce a multi-bit organic ferroelectric-based non-volatile memory with binary readout from a simple capacitor structure. The functioning of our multi-bit concept is quite generally applicable and depends on the following properties for the data storage medium: (a) The data storage medium effectively consists of microscopic switching elements (hysterons). (b) The positive and negative coercive fields of each hysteron are equal in magnitude. (c) The distribution of hysteron coercive fields has substantial width. We show that the organic ferroelectric copolymer P(VDF-TrFE) meets these requirements. All basic properties of our device were measured and modeled in the framework of the dipole switching theory (DST). As a first example we show the possibility to independently program and subsequently read out the lower, middle and upper parts of the hysteron distribution function, yielding a 3-bit memory in a single capacitor structure. All measured devices show good state reproducibility, high endurance and potentially great scalability.

  • 26.
    Khikhlovskyi, Vsevolod
    et al.
    Eindhoven University of Technology, Netherlands.
    van Breemen, Albert J. J. M.
    Holst Centre, TNO, Eindhoven, The Netherlands.
    Janssen, Rene A. J.
    Eindhoven University of Technology, Netherlands.
    Gelinck, Gerwin H.
    Eindhoven University of Technology, Netherlands; TNO, Eindhoven, Netherlands.
    Kemerink, Martijn
    Linköping University, Department of Physics, Chemistry and Biology, Complex Materials and Devices. Linköping University, Faculty of Science & Engineering. Eindhoven University of Technology, Netherlands.
    Data retention in organic ferroelectric resistive switches2016In: Organic electronics, ISSN 1566-1199, E-ISSN 1878-5530, Vol. 31, p. 56-62Article in journal (Refereed)
    Abstract [en]

    Solution-processed organic ferroelectric resistive switches could become the long-missing non-volatile memory elements in organic electronic devices. To this end, data retention in these devices should be characterized, understood and controlled. First, it is shown that the measurement protocol can strongly affect the apparent retention time and a suitable protocol is identified. Second, it is shown by experimental and theoretical methods that partial depolarization of the ferroelectric is the major mechanism responsible for imperfect data retention. This depolarization occurs in close vicinity to the semiconductor-ferroelectric interface, is driven by energy minimization and is inherently present in this type of phase-separated polymer blends. Third, a direct relation between data retention and the charge injection barrier height of the resistive switch is demonstrated experimentally and numerically. Tuning the injection barrier height allows to improve retention by many orders of magnitude in time, albeit at the cost of a reduced on/off ratio. (c) 2016 Elsevier B.V. All rights reserved.

  • 27.
    Koch, N.
    et al.
    Humboldt-Universität zu Berlin, Institut für Physik, Newtonstrasse 15, 12489 Berlin, Germany.
    Salzmann, I.
    Humboldt-Universität zu Berlin, Institut für Physik, Newtonstrasse 15, 12489 Berlin, Germany.
    Johnson, R.L.
    Universität Hamburg, Institut für Experimentalphysik, 22761 Hamburg, Germany.
    Pflaum, J.
    Universität Stuttgart, 3. Physikalisches Institut, 70550 Stuttgart, Germany.
    Friedlein, Rainer
    Linköping University, The Institute of Technology. Linköping University, Department of Physics, Chemistry and Biology, Surface Physics and Chemistry .
    Rabe, J.P.
    Humboldt-Universität zu Berlin, Institut für Physik, Newtonstrasse 15, 12489 Berlin, Germany.
    Molecular orientation dependent energy levels at interfaces with pentacene and pentacenequinone2006In: Organic electronics, ISSN 1566-1199, E-ISSN 1878-5530, Vol. 7, no 6, p. 537-545Article in journal (Refereed)
    Abstract [en]

    We used ultraviolet photoelectron spectroscopy (UPS) to investigate the energy level alignment at contacts between pentacene and Ag(1 1 1) in the presence of interfacial 6,13-pentacenequinone (PQ). Depending on the metal pre-coverage with PQ, we found evidence for three distinctly different interface morphologies and molecular orientations, accompanied by significant changes of the energy level alignment. Consequently, the hole injection barrier between pentacene and Ag(1 1 1) varied between 1.1 eV (pristine Ag) and 0.45 eV (5.4 nm PQ pre-coverage on Ag). In addition, our UPS results suggest that PQ can act as deep trap for electrons in a pentacene matrix. Depending on the exact mutual orientation of PQ and pentacene, the depth of these traps can be in the range of 0.2-0.75 eV. © 2006 Elsevier B.V. All rights reserved.

  • 28.
    Larsen, Christian
    et al.
    Umeå University, Sweden.
    Forchheimer, Robert
    Linköping University, Department of Electrical Engineering, Information Coding. Linköping University, Faculty of Science & Engineering.
    Edman, Ludvig
    Umeå University, Sweden.
    Tu, Deyu
    Linköping University, Department of Electrical Engineering, Information Coding. Linköping University, Faculty of Science & Engineering.
    Design, fabrication and application of organic power converters: Driving light-emitting electrochemical cells from the AC mains2017In: Organic electronics, ISSN 1566-1199, E-ISSN 1878-5530, Vol. 45, p. 57-64Article in journal (Refereed)
    Abstract [en]

    The design, fabrication and operation of a range of functional power converter circuits, based on diode configured organic field-effect transistors as the rectifying unit and capable of transforming a high AC input voltage to a selectable DC voltage, are presented. The converter functionality is demonstrated by selecting and tuning its constituents so that it can effectively drive a low-voltage organic electronic device, a light-emitting electrochemical cell (LEC), when connected to high-voltage AC mains. It is established that the preferred converter circuit for this task comprises an organic full-wave rectifier and a regulation resistor but is void of a smoothing capacitor, and that such a circuit connected to the AC mains (230 V, 50 Hz) successfully can drive an LEC to bright luminance (360 cd m(-2)) and high efficiency (6.4 cd A(-1)). (C) 2017 Elsevier B.V. All rights reserved.

  • 29.
    Li, Weiwei
    et al.
    Linköping University, Department of Physics, Chemistry and Biology, Biomolecular and Organic Electronics. Linköping University, Faculty of Science & Engineering.
    Zhou, Yi
    Linköping University, Department of Physics, Chemistry and Biology, Biomolecular and Organic Electronics. Linköping University, Faculty of Science & Engineering.
    Andersson, Viktor
    Linköping University, Department of Physics, Chemistry and Biology, Biomolecular and Organic Electronics. Linköping University, Faculty of Science & Engineering.
    Andersson, Mattias
    Linköping University, Department of Physics, Chemistry and Biology, Biomolecular and Organic Electronics. Linköping University, The Institute of Technology.
    Thomann, Yi
    Freiburg Material Research Centre, Germany.
    Veit, Clemens
    Fraunhofer Institute for Solar Energy Systems, Germany.
    Tvingstedt, Kristofer
    Linköping University, Department of Physics, Chemistry and Biology, Biomolecular and Organic Electronics. Linköping University, The Institute of Technology.
    Qin, Ruiping
    Beijing Normal University, China.
    Bo, Zhishan
    Beijing Normal University, China.
    Inganäs, Olle
    Linköping University, Department of Physics, Chemistry and Biology, Biomolecular and Organic Electronics. Linköping University, The Institute of Technology.
    Wuerfel, Uli
    Freiburg Material Research Centre, Germany.
    Zhang, Fengling
    Linköping University, Department of Physics, Chemistry and Biology, Biomolecular and Organic Electronics. Linköping University, The Institute of Technology.
    The Effect of additive on performance and shelf-stability of HSX-1/PCBM photovoltaic devices2011In: Organic electronics, ISSN 1566-1199, E-ISSN 1878-5530, Vol. 12, no 9, p. 1544-1551Article in journal (Refereed)
    Abstract [en]

    How 1,8-diiodooctane (DIO) enhances performance of polymer solar cells based on polymer HXS-1 and fullerene [6,6]-phenyl C(71)-butyric acid methyl ester (PC(71)BM) from 3.6% to 5.4% is scrutinized with several techniques by comparing devices or blend films spin-coated from dichlorobenzene (DCB) to those from DCB/DIO (97.5:2.5 v/v). Morphology of blend films is examined with atomic force microscopy (AFM), transmission electron microscopy (TEM) and electron tomography (3-D TEM), respectively. Charge generation and recombination is studied with photoluminescence, and charge transport with field effect transistors. The morphology with domain size in 10-20 nm and vertical elongated clusters formed in DIO system is supposed to facilitate charge transport and minimize charge carrier recombination, which are the main reasons for enhancing power conversion efficiency (PCE) from 3.6% (without DIO) to 5.4% (with DIO). Furthermore, a two year inspection shows no significant impact of DIO on the shelf-stability of the solar cells. No visible degradation in the second year indicates that the morphology of the active layers in the devices is relatively stable after initial relaxation in the first year.

  • 30.
    Li, Xiaodong
    et al.
    Chinese Academic Science, Peoples R China; University of Chinese Academic Science, Peoples R China.
    Wang, Xueyan
    Chinese Academic Science, Peoples R China; University of Chinese Academic Science, Peoples R China.
    Zhang, Wenjun
    Chinese Academic Science, Peoples R China.
    Wu, Yulei
    Chinese Academic Science, Peoples R China.
    Gao, Feng
    Linköping University, Department of Physics, Chemistry and Biology, Biomolecular and Organic Electronics. Linköping University, The Institute of Technology.
    Fang, Junfeng
    Chinese Academic Science, Peoples R China.
    The effect of external electric field on the performance of perovskite solar cells2015In: Organic electronics, ISSN 1566-1199, E-ISSN 1878-5530, Vol. 18, p. 107-112Article in journal (Refereed)
    Abstract [en]

    Planar heterojunction perovskite solar cells were fabricated through a low temperature approach. We find that the device performance significantly depends on the external bias before and during measurements. By appropriate optimization of the bias conditions, we could achieve an 8-fold increase in the power conversion efficiency. The significant improvement in device performance might be caused by the ion motion in the perovskite under the external electric field.

  • 31.
    Li, Xiaoran
    et al.
    TNO, Netherlands; Eindhoven University of Technology, Netherlands.
    van Breemen, Albert J. J. M.
    TNO, Netherlands.
    Khikhlovskyi, Vsevolod
    Eindhoven University of Technology, Netherlands.
    Smits, Edsger C. P.
    TNO, Netherlands.
    Kemerink, Martijn
    Eindhoven University of Technology, Netherlands.
    Broer, Dirk J.
    Eindhoven University of Technology, Netherlands.
    Gelinck, Gerwin H.
    TNO, Netherlands.
    Programmable polymer light emitting transistors with ferroelectric polarization-enhanced channel current and light emission2012In: Organic electronics, ISSN 1566-1199, E-ISSN 1878-5530, Vol. 13, no 9, p. 1742-1749Article in journal (Refereed)
    Abstract [en]

    We present a voltage programmable polymer light emitting field-effect transistor (LEFET), consisting of a green emitting polymer (F8BT), and a ferroelectric polymer, P(VDF-TrFE), as the gate dielectric. We show by both experimental observations and numerical modeling that, when the ferroelectric gate dielectric is polarized in opposite directions at the drain and source sides of the channel, respectively, both electron and hole currents are enhanced, resulting in more charge recombination and similar to 10 times higher light emission in a ferroelectric LEFET, compared to the device with non-ferroelectric gate. As a result of the ferroelectric poling, our ferroelectric LEFETs exhibit repeated programmability in light emission, and an external quantum efficiency (EQE) of up to 1.06%. Numerical modeling reveals that the remnant polarization charge of the ferroelectric layer tends to pin the position of the recombination zone, paving the way to integrate specific optical out-coupling structures in the channel of these devices to further increase the brightness. (C) 2012 Elsevier B.V. All rights reserved.

  • 32.
    Liewald, C.
    et al.
    Ludwig Maximilian Univ Munchen, Germany; NIM, Germany.
    Strohmair, S.
    Ludwig Maximilian Univ Munchen, Germany.
    Hecht, H.
    Ludwig Maximilian Univ Munchen, Germany.
    Glowacki, Eric
    Linköping University, Department of Science and Technology, Physics and Electronics. Linköping University, Faculty of Science & Engineering.
    Nickel, B.
    Ludwig Maximilian Univ Munchen, Germany; NIM, Germany.
    Scanning photocurrent microscopy of electrons and holes in the pigment semiconductor epindolidione2018In: Organic electronics, ISSN 1566-1199, E-ISSN 1878-5530, Vol. 60, p. 51-56Article in journal (Refereed)
    Abstract [en]

    Photocurrent microscopy is used to characterize the kinetics of electrons and holes in organic field-effect transistors (FETs) with the hydrogen-bonded pigment epindolidione as active layer. The method relies on electrons and holes, generated on local illumination, which are provided after exciton splitting, to probe charge trapping. In the dark, hole conduction is observed for negative gate voltage while no electron conduction is observed for positive gate voltage. However, under illumination, a fast displacement current with 60 mu s onset time and 1 ms exponential decay occurs for positive gate voltage, which can be explained by exciton splitting underneath the semitransparent top contact followed by subsequent electron trapping and hole extraction. Afterward, trapped electrons hop via further trap states within the film to the insulator into interface traps (13 ms exponential decay) which induce a positive threshold voltage shift in the FET transfer curves for hole transport. Photocurrent microscopy confirms that the displacement current occurs only for illumination under and near the semitransparent source/drain contacts, which act here as metal-insulator-semiconductor (MIS) diodes. For negative gate voltage instead, the photocurrent comprises an enhanced hole current in the FET channel between the contacts. In the channel region, the detrapping of holes at the interface with the insulator (3 ms time constant) enhances the transistor current at low frequencies amp;lt; 1 kHz, whereas the displacement current between the contacts and the gate is observed only at frequencies amp;gt; 10 kHz. Thus, we show here that photocurrent microscopy allows to identify the kinetics of electrons and holes in traps close to the contacts and in the FET channel of pigment transistors.

  • 33.
    Liu, Jiang
    et al.
    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.
    Half‐Gate Light‐Emitting Electrochemical Transistor to Achieve Centered Emissive Organic p‐n Junction2014In: Organic electronics, ISSN 1566-1199, E-ISSN 1878-5530, Vol. 18, p. 32-36Article in journal (Refereed)
    Abstract [en]

    Conventional organic light-emitting electrochemical cells show promise for lighting applications but in many cases suffer from unbalanced electrochemical doping. A predominant p-doping over n-doping causes an off-centered emissive p-n junction, which leads to poor power-conversion efficiency. Here, we report a half-gate lightemitting electrochemical transistor (HGLECT), in which a ion-conductive gate made from poly(3,4-ethylenedioxythiophene)-poly-(styrenesulfonate) is employed to combat this problem. The gate material, covering half the channel, is used to enhance the ndoping in this part by employing an appropriate operation protocol. We demonstrate a centered light emission zone, closely following the geometry of the gate material. The HGLECT with centered emission profile is shown to be more efficient than the corresponding LEC without gate electrode, and its n-doping level is measured to be 15%.

  • 34.
    Nardes, A. M.
    et al.
    Eindhoven University of Technology, Netherlands.
    Kemerink, M.
    Eindhoven University of Technology, Netherlands.
    de Kok, M. M.
    Philips Research Labs, Netherlands.
    Vinken, E.
    Eindhoven University of Technology, Netherlands.
    Maturova, K.
    Eindhoven University of Technology, Netherlands.
    Janssen, R. A. J.
    Eindhoven University of Technology, Netherlands.
    Conductivity, work function, and environmental stability of PEDOT : PSS thin films treated with sorbitol2008In: Organic electronics, ISSN 1566-1199, E-ISSN 1878-5530, Vol. 9, no 5, p. 727-734Article in journal (Refereed)
    Abstract [en]

    The electrical properties of poly(3,4-ethylenedioxythiophene):poly(4-styrenesulfonate) (PEDOT:PSS) thin films deposited from aqueous dispersion using different concentrations of sorbitol have been studied in detail. Although it is well known that sorbitol enhances the conductivity of PEDOT:PSS thin films by three orders of magnitude, the origin and consequences of sorbitol treatment are only partly understood and subject of further study. By thermal annealing of spin coated PEDOT:PSS/sorbitol films and simultaneously monitoring the conductivity, we demonstrate that the strong increase in conductivity coincides with evaporation of sorbitol from the film. Hence, sorbitol is a processing additive rather than a (secondary) dopant. Scanning Kelvin probe microscopy reveals that sorbitol treatment causes a reduction of the work function from 5.1 eV to 4.8-4.9 eV. Sorbitol also influences the environmental stability of the films. While the conductivity of the pristine PEDOT:PSS films increases by about one order of magnitude at similar to 50% RH due to an ionic contribution to the overall conductivity, films prepared using sorbitol exhibit an increased environmental stability with an almost constant conductivity up to 45% RH and a slight decrease at 50% RH. The higher stability results from a reduced tendency to take up water from the air, which is attributed to a denser packing of the PEDOT:PSS after sorbitol treatment. (C) 2008 Elsevier B.V. All rights reserved.

  • 35.
    Petsagkourakis, Ioannis
    et al.
    University of Bordeaux, France.
    Pavlopoulou, Eleni
    Institute Polytech Bordeaux Bordeaux INP, France.
    Cloutet, Eric
    University of Bordeaux, France.
    Fang Chen, Yan
    University of Bordeaux, 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.
    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.
    Dilhaire, Stefan
    University of Bordeaux, France.
    Fleury, Guillaume
    University of Bordeaux, France.
    Hadziioannou, Georges
    University of Bordeaux, France.
    Correlating the Seebeck coefficient of thermoelectric polymer thin films to their charge transport mechanism2018In: Organic electronics, ISSN 1566-1199, E-ISSN 1878-5530, Vol. 52, p. 335-341Article in journal (Refereed)
    Abstract [en]

    Room temperature flexible heat harvesters based on conducting polymers are ideally suited to cover the energy demands of the modern nomadic society. The optimization of their thermoelectric efficiency is usually sought by tuning the oxidation levels of the conducting polymers, even if such methodology is detrimental to the Seebeck coefficient (S) as both the Seebeck coefficient and the electrical conductivity (sigma) are antagonistically related to the carrier concentration. Here we report a concurrent increase of S and sigma and we experimentally derive the dependence of Seebeck coefficient on charge carrier mobility for the first time in organic electronics. Through specific control of the conducting polymer synthesis, we enabled the formation of a denser percolation network that facilitated the charge transport and the thermodiffusion of the charge carriers inside the conducting polymer layer, while the material shifted from a Fermi glass towards a semi-metal, as its crystallinity increased. This work sheds light upon the origin of the thermoelectric properties of conducting polymers, but also underlines the importance of enhanced charge carrier mobility for the design of efficient thermoelectric polymers.

  • 36.
    Pettersson, Lars
    et al.
    Linköping University, The Institute of Technology. Linköping University, Department of Physics, Chemistry and Biology.
    Ghosh, S.
    Inganäs, Olle
    Linköping University, The Institute of Technology. Linköping University, Department of Physics, Chemistry and Biology, Biomolecular and Organic Electronics .
    Optical anisotropy in thin films of poly(3,4-ethylenedioxythiophene)- poly(4-styrenesulfonate)2002In: Organic electronics, ISSN 1566-1199, E-ISSN 1878-5530, Vol. 3, no 3-4, p. 143-148Article in journal (Refereed)
    Abstract [en]

    Anisotropic optical constants spectrum of spin-coated thin films of poly(3,4-ethylenedioxythiophene)-poly(4-styrenesulfonate) (PEDOT-PSS) from 200 to 1700 nm were determined using variable-angle spectroscopic ellipsometry and polarized intensity transmission data together with absorption spectroscopy. PEDOT-PSS was found to be very anisotropic, uniaxial with the optic axis parallel to the surface normal. The result is in good agreement with results obtained of chemically polymerized PEDOT layers doped with toluenesulfonate. By adding sorbitol to the PEDOT-PSS dispersion before spin-coating, layers with a higher conductivity were obtained. A detailed study was made of the optical response of these layers in comparison to the PEDOT-PSS prepared from dispersions without sorbitol. The optical anisotropy is important to consider when using PEDOT-PSS in optoelectronic devices, such as polymer light-emitting diodes and photovoltaic devices. © 2002 Elsevier Science B.V. All rights reserved.

  • 37.
    Pilet, N.
    et al.
    PSI, Switzerland.
    Khikhlovskyi, V.
    Eindhoven University of Technology, Netherlands.
    van Breemen, A. J. J. M.
    TNO Dutch Org Appl Science Research, Netherlands.
    Michels, J. J.
    TNO Dutch Org Appl Science Research, Netherlands; Max Planck Institute Polymer Research, Germany.
    Kemerink, Martijn
    Linköping University, Department of Physics, Chemistry and Biology, Complex Materials and Devices. Linköping University, Faculty of Science & Engineering. Eindhoven University of Technology, Netherlands.
    Gelinck, G.
    Eindhoven University of Technology, Netherlands; TNO Dutch Org Appl Science Research, Netherlands.
    Warnicke, P.
    PSI, Switzerland.
    Bernard, L.
    Swiss Federal Labs Mat Science and Technology, Switzerland.
    Piezoelectricity enhancement of P(VDF/TrFE) by X-ray irradiation2016In: Organic electronics, ISSN 1566-1199, E-ISSN 1878-5530, Vol. 37, p. 257-262Article in journal (Refereed)
    Abstract [en]

    Organic electronics is becoming more and more important because the low level of fabrication and deposition complexity even at large scale makes it a good candidate for future low cost technological product development. P(VDF-TrFE) is a co-polymer of special interest due its ferroelectric property enabling usage in re-programmable non-volatile organic memory and magnetoelectric sensors. Piezo force microscopy (PFM) provides access to the technologically relevant ferroelectric polarisability and its remanent polarization via imaging of the piezoelectric property. Here we use PFM to show that piezoelectric response of a P(VDF-TrFE) film can be enhanced by up to 260 % after soft X-ray irradiation. This enhancement correlates with morphological change of part of the film, from amorphous to crystalline. An optimal irradiation dose is found above which the film gets eroded and the piezoelectric response gets lowered. (C) 2016 Elsevier B.V. All rights reserved.

  • 38.
    Roelofs, W. S. Christian
    et al.
    Eindhoven University of Technology, Netherlands; Philips Research Labs, Netherlands.
    Li, Weiwei
    Eindhoven University of Technology, Netherlands.
    Janssen, Rene A. J.
    Eindhoven University of Technology, Netherlands.
    de Leeuw, Dago M.
    Max Planck Institute Polymer Research, Germany; King Abdulaziz University, Saudi Arabia.
    Kemerink, Martijn
    Linköping University, Department of Physics, Chemistry and Biology, Complex Materials and Devices. Linköping University, The Institute of Technology. Eindhoven University of Technology, Eindhoven, The Netherlands.
    Contactless charge carrier mobility measurement in organic field-effect transistors2014In: Organic electronics, ISSN 1566-1199, E-ISSN 1878-5530, Vol. 15, no 11, p. 2855-2861Article in journal (Refereed)
    Abstract [en]

    With the increasing performance of organic semiconductors, contact resistances become an almost fundamental problem, obstructing the accurate measurement of charge carrier mobilities. Here, a generally applicable method is presented to determine the true charge carrier mobility in an organic field-effect transistor (OFET). The method uses two additional finger-shaped gates that capacitively generate and probe an alternating current in the OFET channel. The time lag between drive and probe can directly be related to the mobility, as is shown experimentally and numerically. As the scheme does not require the injection or uptake of charges it is fundamentally insensitive to contact resistances. Particularly for ambipolar materials the true mobilities are found to be substantially larger than determined by conventional (direct current) schemes.

  • 39.
    Said, Elias
    et al.
    Linköping University, Department of Science and Technology. Linköping University, The Institute of Technology.
    Andersson, Peter
    ACREO AB, Bredgatan 34, SE-602 21 Norrköping, Sweden.
    Engquist, Isak
    Linköping University, Department of Science and Technology. Linköping University, The Institute of Technology.
    Crispin, Xavier
    Linköping University, Department of Science and Technology. Linköping University, The Institute of Technology.
    Berggren, Magnus
    Linköping University, Department of Science and Technology. Linköping University, The Institute of Technology.
    Electrochromic display cells driven by an electrolyte-gated organic field-effect transistor2009In: Organic electronics, ISSN 1566-1199, E-ISSN 1878-5530, Vol. 10, no 6, p. 1195-1199Article in journal (Refereed)
    Abstract [en]

    Monolithic integration of an electrolyte-gated organic field-effect transistor (OFET) and an organic electrochromic pixel is reported. Thanks to its versatility, the polyanionic proton conductor poly(styrenesulfonic acid) (PSSH) can serve both as the gate “insulator” in OFETs and as the electrolyte in electrochromic display pixels. Employing identical materials in both the display cells and in the driver transistors is a necessary prerequisite to achieve robust displays possible to manufacture on flexible carriers using printing tools. Smart pixels combining depletion mode electrochemical transistors and electrochromic displays have been reported in the past. Here, an enhancement mode OFET as the driver enables relatively shorter updating times and much simpler addressing and updating schemes.

  • 40.
    Sinno, Hiam
    et al.
    Linköping University, Department of Science and Technology, Physics and Electronics. Linköping University, The Institute of Technology.
    Nguyen, Ha Tran
    University of Mons-UMONS, Belgium.
    Hägerström, Anders
    Linköping University, Department of Science and Technology, Physics and 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.
    Lindell, Linda
    Linköping University, Department of Physics, Chemistry and Biology, Surface Physics and Chemistry. Linköping University, The Institute of Technology.
    Coulembier, Olivier
    University of Mons-UMONS, Belgium.
    Dubois, Philippe
    University of Mons-UMONS, Belgium.
    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.
    Amphiphilic semiconducting copolymer as compatibility layer for printing polyelectrolyte-gated OFETs2013In: Organic electronics, ISSN 1566-1199, E-ISSN 1878-5530, Vol. 14, no 3, p. 790-796Article in journal (Refereed)
    Abstract [en]

    We report a method for inkjet-printing an organic semiconductor layer on top of the electrolyte insulator layer in polyelectrolyte-gated OFETs by using a surface modification treatment to overcome the underlying wettability problem at this interface. The method includes depositing an amphiphilic diblock copolymer (P3HT-b-PDMAEMA). This material is designed to have one set of blocks that mimics the hydrophobic properties of the semiconductor (poly(3-hexylthiophene) or P3HT), while the other set of blocks include polar components that improve adhesion to the polyelectrolyte insulator. Contact angle measurements, atomic force microscopy, and X-ray photoelectron spectroscopy confirm formation of the desired surface modification film. Successful inkjet printing of a smooth semiconductor layer allows us to manufacture complete transistor structures that exhibit low-voltage operation in the range of 1 V.

  • 41.
    Sun, Zhengyi
    et al.
    Fudan University, Shanghai, China.
    Ding, Xunmin
    Fudan University, Shanghai, China.
    Ding, Baofu
    Fudan University, Shanghai, China.
    Gao, Xindong
    Fudan University, Shanghai, China.
    Hu, Yongmao
    Fudan University, Shanghai, China.
    Chen, Xiaoqing
    Fudan University, Shanghai, China.
    He, Yun
    Fudan University, Shanghai, China.
    Hou, Xiaoyuan
    Fudan University, Shanghai, China.
    Buffer-enhanced electron injection in organic light-emitting devices with copper cathode2013In: Organic electronics, ISSN 1566-1199, E-ISSN 1878-5530, Vol. 14, no 2, p. 511-515Article in journal (Refereed)
    Abstract [en]

    We explore in this work the use of Cu as a cathode material in organic light-emitting devices (OLEDs) and find a dual electron–injection enhancement mechanism derived from the LiF layer. Different from what observed previously in Ag- and Au-cathode devices, the LiF buffer layer in the Cu-cathode OLEDs starts to play its role in performance improvement when it is much thinner than 3 nm, the optimal value of buffer thickness, and in the case of optimal thickness, the device exhibits excellent performance comparable to conventional Al-cathode device. The phenomenon observed is ascribed to enhanced electron injection as a result of combined effect of interfacial reaction and tunneling barrier reduction mechanism: while chemical reaction plays a key role at the very beginning of interface formation, tunneling dominates in the subsequent stage leading to the tremendous improvement of the characteristics.

  • 42.
    Sun, Zhengyi
    et al.
    Linköping University, Department of Physics, Chemistry and Biology, Surface Physics and Chemistry. Linköping University, The Institute of Technology.
    Zhan, Yiqiang
    Fudan University, Shanghai, China.
    Shi, Shengwei
    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.
    Energy level alignment and interactive spin polarization at organic/ferromagnetic metal interfaces for organic spintronics2014In: Organic electronics, ISSN 1566-1199, E-ISSN 1878-5530, Vol. 15, no 9, p. 1951-1957Article in journal (Refereed)
    Abstract [en]

    Energy level alignment and spin polarization at tetracyanoquinodimethane/Fe and acridine orange base/Fe interfaces are investigated by means of photoelectron spectroscopy and X-ray magnetic circular dichroism (XMCD), respectively, to explore their potential application in organic spintronics. Interface dipoles are observed at both hybrid interfaces, and the work function of Fe is increased by 0.7 eV for the tetracyanoquinodimethane (TCNQ) case, while it is decreased by 1.2 eV for the acridine orange base (AOB) case. According to XMCD results, TCNQ molecule has little influence on the spin polarization of Fe surface. In contrast, AOB molecule reduces the interfacial spin polarization of Fe significantly. Induced spin polarization of the two organic molecules at the interfaces is not observed. The results reveal the necessity of investigating the magnetic property changes of both the OSC and the FM during the process of energy level alignment engineering.

  • 43.
    Tengstedt, Carl
    et al.
    Linköping University, Department of Science and Technology. Linköping University, The Institute of Technology.
    Crispin, Annica
    Linköping University, Department of Physics, Chemistry and Biology. Linköping University, The Institute of Technology.
    Hsu, C.
    Dupont Displays, The Experimental Station, Wilmington, USA.
    Zhang, C.
    Dupont Displays, Santa Barbara, USA.
    Parker, I.D.
    Dupont Displays, Santa Barbara, USA.
    Salaneck, William R
    Linköping University, Department of Physics, Chemistry and Biology. Linköping University, The Institute of Technology.
    Fahlman, Mats
    Linköping University, Department of Science and Technology. Linköping University, The Institute of Technology.
    Study and comparison of conducting polymer hole injection layers in light emitting devices2005In: Organic electronics, ISSN 1566-1199, E-ISSN 1878-5530, Vol. 6, no 1, p. 21-33Article in journal (Refereed)
    Abstract [en]

    A set of polyaniline- and poly(3,4-ethylene dioxythiophene)-based materials were studied as hole injection layers in polymer light emitting devices. The choice of polymeric counterion/dopant poly(styrenesulfonic acid), and poly(acrylamido-2-methyl-1-propanesulfonic acid), and poly(acrylamide) blended with polyaniline/poly(acrylamido-2-methyl-1-propanesulfonic acid) was found to influence both work function and film morphology, which in turn affects device performance. The work functions of the polymer films spanned the range of over 1 eV and the surface region of the films were found to be low in conducting polymer content compared to the bulk. This was particularly the case of the polyaniline/poly(acrylamido-2-methyl-1-propanesulfonic acid) blended with poly(acrylamide) which showed device efficiency equal to that of the poly(3,4-ethylene dioxythiophene)–poly(styrenesulfonic acid) reference. The turn on voltage, however, was significantly larger, likely due to the insulating poly(acrylamide)-rich surface region of the polyaniline/poly(acrylamido-2-methyl-1-propanesulfonic acid)/poly(acrylamide) film. The polymer blend of polyaniline/poly(styrenesulfonic acid) yielded the highest work function (5.5 ± 0.1 eV).

  • 44.
    Toss, Henrik
    et al.
    Linköping University, Department of Science and Technology, Physics and Electronics. Linköping University, The Institute of Technology.
    Suspene, Clement
    University of Paris Diderot, France .
    Piro, Benoit
    University of Paris Diderot, France .
    Yassar, Abderrahim
    Ecole Polytechnique, Palaiseau, France.
    Crispin, Xavier
    Linköping University, Department of Science and Technology, Physics and Electronics. Linköping University, The Institute of Technology.
    Kergoat, Loig
    Linköping University, Department of Science and Technology, Physics and Electronics. Linköping University, The Institute of Technology.
    Pham, Minh-Chau
    University of Paris Diderot, France .
    Berggren, Magnus
    Linköping University, Department of Science and Technology, Physics and Electronics. Linköping University, The Institute of Technology.
    On the mode of operation in electrolyte-gated thin film transistors based on different substituted polythiophenes2014In: Organic electronics, ISSN 1566-1199, E-ISSN 1878-5530, Vol. 15, no 10, p. 2420-2427Article in journal (Refereed)
    Abstract [en]

    Organic Thin Film Transistors (OTFT), gated through an aqueous electrolyte, have extensively been studied as sensors in various applications. These water-gated devices are known to work both as electrochemical (Organic ElectroChemical Transistor - OECT) and field-effect (Organic Field-Effect Transistor - OFET) devices. To properly model and predict the response of water-gated OTFT sensors it is important to distinguish between the mechanism, field-effect or electrochemical, by which the transistor is modulated and thus how the gate signal can be affected by the analyte. In this present study we explore three organic polymer semiconductors, poly-(3-hexyl-thiophene) (P3HT), poly-(3-carboxypentyl-thiphene) (P3CPT) and a co-polymer P3HT-co-poly-(3-ethoxypentanoic acid-thiophene) (monomer ratio 1:6, P3HT-COOH15) in water-gated OTFT structures. We report a set of transistor characteristics, including standard output parameters, impedance spectroscopy and current transients, to investigate the origin of the mode of operation in these water-gated OTFTs. Impedance characteristics, including both frequency and voltage dependence, were recorded for capacitor stacks corresponding to the gate/electrolyte/semiconductor/source structure. It is shown that P3HT as well as P3HT-COOH15 both can function as semiconductors in water gated OTFT devices operating in field-effect mode. P3CPT on the other hand shows typical signs of electrochemical mode of operation. The -COOH side group has been suggested as a possible anchoring site for biorecognition elements in EGOFET sensors, rendering P3HT-COOH15 a possible candidate for such applications.

  • 45.
    Tzamalis, Georgios
    et al.
    Linköping University, Department of Physics, Chemistry and Biology. Linköping University, The Institute of Technology.
    Crispin, Xavier
    Linköping University, The Institute of Technology. Linköping University, Department of Science and Technology, Physics and Electronics.
    Andersson, Mats
    Chalmers.
    Berggren, Magnus
    Linköping University, Department of Science and Technology, Physics and Electronics. Linköping University, The Institute of Technology.
    Electrochemical control of amplified spontaneous emission in conjugated polymers2012In: Organic electronics, ISSN 1566-1199, E-ISSN 1878-5530, Vol. 13, no 6, p. 954-958Article in journal (Refereed)
    Abstract [en]

    We present a method of electrochemically tuning the threshold intensity of the amplified spontaneous emission (ASE) of a semiconducting polymer thin film. This can be achieved in close contact with a conducting polymer electrode (PEDOT:PSS), if the latter is electrochemically tuned to an optically transparent redox state for the emitted wavelength of interest. This electrical switch between ASE and fluorescence hints that a new route to achieve electrically pumped laser is by combining an electrochemical device with a lasing conjugated polymer.

  • 46. Van, Der Gon A.W.D.
    et al.
    Birgerson, J.
    Fahlman, Mats
    Linköping University, The Institute of Technology. Linköping University, Department of Physics, Chemistry and Biology, Surface Physics and Chemistry .
    Salaneck, William R
    Linköping University, The Institute of Technology. Linköping University, Department of Physics, Chemistry and Biology, Surface Physics and Chemistry .
    Modification of PEDOT-PSS by low-energy electrons2002In: Organic electronics, ISSN 1566-1199, E-ISSN 1878-5530, Vol. 3, no 3-4, p. 111-118Article in journal (Refereed)
    Abstract [en]

    The stability of conjugated organic materials under electron transport is of great importance for the lifetime of devices such as polymer light-emitting diodes (PLEDs). Here, the modification of thin films of poly(3,4- ethylenedioxythiophene) oxidized with poly(4-styrenesulfonate) (known as PEDOT-PSS, often used in the fabrication of PLEDs) by low-energy electrons has been studied using X-ray photo-electron spectroscopy. Thin films of PSSH and molecular solid films of EDOT molecules also have been studied. We find that electrons with kinetic energies as low as 3 eV result in significant modification of the chemical structure of the materials. For thin films of PSSH, the electron bombardment leads to a strong loss of oxygen and a smaller loss of sulfur. In addition, a large amount of the sulfur atoms that remain in the films exhibits a different binding energy because of scissions of the bonds to oxygen atoms. For condensed molecular solid films of EDOT molecules, we find that the carbon atoms bonded to oxygen react and form additional bonds, as evidenced by a new component in the C(1s) peak at a higher binding energy. In the PEDOT-PSS blend, we find both effects. The importance of these observations for light-emitting diodes incorporating PEDOT-PSS films is discussed. This work demonstrates that the combination of in situ low-energy electron bombardment in combination with photo-electron spectroscopy is a powerful method to simulate and study certain processes, associated with low-energy electrons, occurring in organic based devices, which cannot be studied directly otherwise. © 2002 Elsevier Science B.V. All rights reserved.

  • 47.
    van Reenen, S.
    et al.
    Eindhoven University of Technology, Netherlands.
    Janssen, R. A. J.
    Eindhoven University of Technology, Netherlands.
    Kemerink, M.
    Eindhoven University of Technology, Netherlands.
    Doping dynamics in light-emitting electrochemical cells2011In: Organic electronics, ISSN 1566-1199, E-ISSN 1878-5530, Vol. 12, no 10, p. 1746-1753Article in journal (Refereed)
    Abstract [en]

    A major drawback of light-emitting electrochemical cells (LECs) is the long time scale associated with switching, during which ions redistribute in the active layer. We present a numerical modeling study that gives fundamental insight in the dynamics during turn-on. The characteristic response of LECs to an applied bias is the electrochemical doping of the active layer by doping fronts moving across the active layer. Formation and motion of such doping fronts are shown to be intimately related to both the electronic and ionic mobility and therefore provide useful information regarding these two quantities in LECs. In particular, it is shown that the switch-on time in LECs is directly related to the time an ion needs to cross approximately half the device, enabling the extraction of the ion mobility from the switch-on time. (C) 2011 Elsevier B.V. All rights reserved.

  • 48.
    van Reenen, S.
    et al.
    Eindhoven University of Technology, Netherlands.
    Scheepers, M.
    Eindhoven University of Technology, Netherlands.
    van de Ruit, K.
    Eindhoven University of Technology, Netherlands.
    Bollen, D.
    Agfa Gevaert NV, Belgium.
    Kemerink, Martijn
    Linköping University, Department of Physics, Chemistry and Biology, Complex Materials and Devices. Linköping University, The Institute of Technology.
    Explaining the effects of processing on the electrical properties of PEDOT:PSS2014In: Organic electronics, ISSN 1566-1199, E-ISSN 1878-5530, Vol. 15, no 12, p. 3710-3714Article in journal (Refereed)
    Abstract [en]

    By simultaneously measuring the Seebeck coefficient and the conductivity in differently processed PEDOT:PSS films, fundamental understanding is gained on how commonly used processing methods improve the conductivity of PEDOT:PSS. Use of a high boiling solvent (HBS) enhances the conductivity by 3 orders of magnitude, as is well-known. Simultaneously, the Seebeck coefficient S remains largely unaffected, which is shown to imply that the conductivity is improved by enhanced connectivity between PEDOT-rich filaments within the film, rather than by improved conductivity of the separate PEDOT filaments. Post-treatment of PEDOT: PSS films by washing with H2SO4 leads to a similarly enhanced conductivity and a significant reduction in the layer thickness. This reduction strikingly corresponds to the initial PSS ratio in the PEDOT:PSS films, which suggests removal and replacement of PSS in PEDOT:PSS by HSO4- or SO42- after washing. Like for the HBS treatment, this improves the connectivity between PEDOT filaments. Depending on whether the H2SO4 treatment is or is not preceded by an HBS treatment also the intra-filament transport is affected. We show that by characterization of S and sigma it is possible to obtain more fundamental understanding of the effects of processing on the (thermo) electrical characteristics of PEDOT:PSS.

  • 49.
    van Reenen, Stephan
    et al.
    Eindhoven University of Technology, The Netherlands.
    Kemerink, Martijn
    Linköping University, Department of Physics, Chemistry and Biology, Complex Materials and Devices. Linköping University, The Institute of Technology. Eindhoven University of Technology, The Netherlands.
    Correcting for contact geometry in Seebeck coefficient measurements of thin film devices2014In: Organic electronics, ISSN 1566-1199, E-ISSN 1878-5530, Vol. 15, no 10, p. 2250-2255Article in journal (Refereed)
    Abstract [en]

    Driven by promising recent results, there has been a revived interest in the thermoelectric properties of organic (semi) conductors. Concomitantly, there is a need to probe the Seebeck coefficient S of modestly conducting materials in thin film geometry. Here we show that geometries that seem desirable from a signal-to-noise perspective may induce systematic errors in the measured value of S, S-m, by a factor 3 or more. The enhancement of S-m by the device geometry is related to competing conduction paths outside the region between the electrodes. We derive a universal scaling curve that allows correcting for this and show that structuring the semiconductor is not needed for the optimal electrode configuration, being a set of narrow, parallel strips.

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