Organic photovoltaic devices based on polythiophene films electrodeposited on FTO substrates

Abstract We investigated photovoltaic devices based on electrochemically deposited monolayer of neat polythiophene (PT) films onto fluorine-doped tin oxide (FTO)/glass substrates. The photo-electrical behavior of these devices, using FTO and aluminum as electrodes, presented symbatic and antibatic response. These devices presented Voc∼700 mV, under monochromatic irradiation (λ=610 nm; 1 W/m2) and the Incident Photon Converted to Electron Efficiency (IPCE) around 5%, with illumination through the FTO electrode (λ=610 nm; 1 W/m2). Cyclic voltammogramms and optical measurements were used to estimate the PT HOMO and LUMO energy levels, as well to demonstrate that the potential synthesis did not produce any polymer degradation. Using the Schottky model expression in the dark current voltage characteristics it was possible to obtain the barrier height value (ϕb), for the interface PT/Al. The ϕb was quite near to the difference between the aluminum work function and the PT electronic affinity and coherent with the Voc values.

[1]  K. Potje-Kamloth,et al.  Electrical and chemical sensing properties of doped polypyrrole/gold Schottky barrier diodes , 1999 .

[2]  Michael D. McGehee,et al.  Conjugated Polymer Photovoltaic Cells , 2004 .

[3]  I. A. Hümmelgen,et al.  Considerations about the electrochemical estimation of the ionization potential of conducting polymers , 2002 .

[4]  G. Shi,et al.  LOW POTENTIAL ELECTROPOLYMERIZATION OF THIOPHENE AT A COPPER OXIDE ELECTRODE , 1999 .

[5]  N. Félidj,et al.  Surface-enhanced Raman scattering study of polyalkylthiophenes on gold electrodes and in silver colloids , 2001 .

[6]  D. C. Trivedi,et al.  A new route to synthesize high degree polythiophene in a room temperature melt medium , 2005 .

[7]  I. A. Hümmelgen,et al.  Influence of film thickness on charge transport of electrodeposited polypyrrole thin films , 2002 .

[8]  Teketel Yohannes,et al.  Polymer-electrolyte-based photoelectrochemical solar energy conversion with poly(3-methylthiophene) photoactive electrode , 1996 .

[9]  Mats Andersson,et al.  High Quantum Efficiency Polythiophene , 1998 .

[10]  Stephen R. Forrest,et al.  Small molecular weight organic thin-film photodetectors and solar cells , 2003 .

[11]  X. Crispin.  Interface dipole at organic/metal interfaces and organic solar cells , 2004 .

[12]  A. Goetzberger,et al.  Photovoltaic materials, history, status and outlook , 2003 .

[13]  Amal K. Ghosh,et al.  Merocyanine organic solar cells , 1978 .

[14]  Donal D. C. Bradley,et al.  Electrochemical determination of the ionization potential and electron affinity of poly(9,9-dioctylfluorene) , 1998 .

[15]  M. Skompska,et al.  The influence of the structural defects and microscopic aggregation of poly(3-alkylthiophenes) on electrochemical and optical properties of the polymer films: discussion of an origin of redox peaks in the cyclic voltammograms , 2001 .

[16]  Su-Moon Park,et al.  Electrochemistry of Conductive Polymers. 33. Electrical and Optical Properties of Electrochemically Deposited Poly(3-methylthiophene) Films Employing Current-Sensing Atomic Force Microscopy and Reflectance Spectroscopy , 2004 .

[17]  A. Kahn,et al.  Electronic structure, diffusion, and p-doping at the Au/F16CuPc interface , 2001 .

[18]  Xianyu Deng,et al.  Fluorene-based low band-gap copolymers for high performance photovoltaic devices , 2004 .

[19]  William R. Salaneck,et al.  The chemical and electronic structure of the interface between aluminum and polythiophene semiconductors , 1993 .

[20]  M. S. Dresselhaus,et al.  Intercalate ordering in first stage graphite-lithium , 1979 .

[21]  I. A. Hümmelgen,et al.  Sulfonated polyaniline/poly(3-methylthiophene)-based photovoltaic devices. , 2006 .

[22]  A. Vadivel Murugan,et al.  Electrochemically synthesised conducting polymeric materials for applications towards technology in electronics, optoelectronics and energy storage devices , 1999 .

[23]  I. A. Hümmelgen,et al.  The electronic behavior of poly(3-octylthiophene) electrochemically synthesized onto Au substrate , 2003 .

[24]  E. J. Evans,et al.  Photovoltaic devices based on polythiophenes and substituted polythiophenes , 2001 .

[25]  M. Durstock,et al.  An Investigation of Poly(thienylene vinylene) in Organic Photovoltaic Devices , 2004 .

[26]  M. Andersson,et al.  Photodiode performance and nanostructure of polythiophene/C60 blends , 1997 .

[27]  Wojciech Domagala,et al.  Electrochemical overoxidation of poly(3,4-ethylenedioxythiophene)—PEDOT studied by means of in situ ESR spectroelectrochemistry , 2005 .

[28]  C. Brabec,et al.  Plastic Solar Cells , 2001 .

[29]  I. A. Hümmelgen,et al.  Electrochemically deposited poly(3-methylthiophene) performance in single layer photovoltaic devices , 2003, The European physical journal. E, Soft matter.

[30]  Yang Yang,et al.  Solvation induced morphological effects on the polymer/metal contacts , 2001 .

[31]  Christoph J. Brabec,et al.  Organic photovoltaics: technology and market , 2004 .

[32]  Frederik C. Krebs,et al.  A brief history of the development of organic and polymeric photovoltaics , 2004 .

[33]  O. Inganäs,et al.  Correlation between oxidation potential and open-circuit voltage of composite solar cells based on blends of polythiophenes/ fullerene derivative , 2004 .

[34]  Zakya H. Kafafi,et al.  Initial stages of metal/organic semiconductor interface formation , 2000 .

[35]  I. A. Hümmelgen,et al.  Charge injection and transport in electrochemical films of poly(3-hexylthiophene) , 2002 .

[36]  I. A. Hümmelgen,et al.  The influence of electrode material on charge transport properties of polypyrrole thin films , 2001 .

[37]  R. C. Weast.  CRC Handbook of Chemistry and Physics , 1973 .

[38]  Yongfang Li,et al.  Electrochemical overoxidation of conducting polypyrrole nitrate film in aqueous solutions , 2000 .

[39]  Lihua Zhu,et al.  Chronocoulometric determination of doping levels of polythiophenes: influences of overoxidation and capacitive processes , 2000 .

[40]  Temperature dependent characteristics of poly(3 hexylthiophene)-fullerene based heterojunction organic solar cells , 2003 .

[41]  Zhang Wen-bin,et al.  Doping effects on the polymer-chain structure of poly(3-methythiophene) , 1992 .

[42]  V. Mihailetchi,et al.  Cathode dependence of the open-circuit voltage of polymer:fullerene bulk heterojunction solar cells , 2003 .

[43]  Wuxia Li,et al.  Effect of electrode modification on organic photovoltaic devices , 2006 .