A [3,2-b]thienothiophene-alt-benzothiadiazole copolymer for photovoltaic applications: design, synthesis, material characterization and device performances

The synthesis of a new alternating copolymer (PTBzT2-C12) based on a thiophene-benzothiadiazole-thiophene (TBzT) segment and a thieno[3,2-b]thiophene unit and its utilization as electron donor in photovoltaic bulk heterojunctions are reported. The copolymer has been obtained via a Stille cross-coupling reaction. The material's optical and electrochemical properties, in solution or in thin films, have been investigated using UV-visible absorption as well as photoluminescence spectroscopy and cyclic voltammetry. A significant red-shift of the absorption edge is observed during film formation, leading to an optical bandgap of 1.88 eV. The polymer ionisation potential is as high as 5.3 eV and makes the material particularly interesting for photovoltaic applications since it is a prerequisite for high open circuit voltages and better chemical stability. Bulk heterojunction solar cells using blends of the copolymer, as the electron donor, and [6,6]-phenyl-C61-butyric acid methyl ester (PCBM), as the electron transporting material, have been elaborated. A power conversion efficiency of 1% is achieved with a 1:4 PTBzT2-C12:PCBM weight ratio and a 30 nm semi-transparent active layer. The open-circuit voltage is equal to 0.74 V and agrees with the expected value. It is anticipated from the copolymer optoelectronic properties, that this novel material should allow power conversion efficiencies above 5% after further optimization of the processing steps.

[1]  Mm Martijn Wienk,et al.  Narrow‐Bandgap Diketo‐Pyrrolo‐Pyrrole Polymer Solar Cells: The Effect of Processing on the Performance , 2008 .

[2]  Ping Liu,et al.  Thiophene polymer semiconductors for organic thin-film transistors. , 2008, Chemistry.

[3]  M. Ratner,et al.  Synthesis, characterization, and transistor response of semiconducting silole polymers with substantial hole mobility and air stability. Experiment and theory. , 2008, Journal of the American Chemical Society.

[4]  Stefan C J Meskers,et al.  Compositional and electric field dependence of the dissociation of charge transfer excitons in alternating polyfluorene copolymer/fullerene blends. , 2008, Journal of the American Chemical Society.

[5]  Christoph J. Brabec,et al.  Two Novel Cyclopentadithiophene-Based Alternating Copolymers as Potential Donor Components for High-Efficiency Bulk-Heterojunction-Type Solar Cells , 2008 .

[6]  F. Wudl,et al.  Two Poly(2,5-thienythiazolothiazole)s: Observation of Spontaneous Ordering in Thin Films† , 2008 .

[7]  M. McGehee,et al.  Organic bulk heterojunction solar cells using poly(2,5-bis(3-tetradecyllthiophen-2-yl)thieno[3,2,-b]thiophene) , 2008 .

[8]  Jin Young Kim,et al.  Processing additives for improved efficiency from bulk heterojunction solar cells. , 2008, Journal of the American Chemical Society.

[9]  Jenny Nelson,et al.  Morphology evolution via self-organization and lateral and vertical diffusion in polymer:fullerene solar cell blends. , 2008, Nature materials.

[10]  Junbiao Peng,et al.  High-performance polymer heterojunction solar cells of a polysilafluorene derivative , 2008 .

[11]  Ye Tao,et al.  Toward a rational design of poly(2,7-carbazole) derivatives for solar cells. , 2008, Journal of the American Chemical Society.

[12]  Rui Zhang,et al.  Novel Thiophene‐Thiazolothiazole Copolymers for Organic Field‐Effect Transistors , 2007 .

[13]  A. Matzger,et al.  Dialkyl-Substituted Thieno[3,2-b]thiophene-Based Polymers Containing 2,2‘-Bithiophene, Thieno[3,2-b]thiophene, and Ethynylene Spacers , 2007 .

[14]  M. Chabinyc,et al.  Regioregular poly(3-hexyl)selenophene: a low band gap organic hole transporting polymer. , 2007, Chemical communications.

[15]  A. Rinzler,et al.  Low band gap EDOT-benzobis(thiadiazole) hybrid polymer characterized on near-IR transmissive single walled carbon nanotube electrodes. , 2007, Chemical communications.

[16]  Luping Yu,et al.  Plastic Near‐Infrared Photodetectors Utilizing Low Band Gap Polymer , 2007 .

[17]  Mario Leclerc,et al.  A New Poly(2,7‐Dibenzosilole) Derivative in Polymer Solar Cells , 2007 .

[18]  Mario Leclerc,et al.  A Low‐Bandgap Poly(2,7‐Carbazole) Derivative for Use in High‐Performance Solar Cells , 2007 .

[19]  Jean Roncali,et al.  Molecular Engineering of the Band Gap of π-Conjugated Systems: Facing Technological Applications , 2007 .

[20]  Yang Yang,et al.  Manipulating regioregular poly(3-hexylthiophene) : [6,6]-phenyl-C61-butyric acid methyl ester blends—route towards high efficiency polymer solar cells , 2007 .

[21]  Weihua Tang,et al.  Conjugated Copolymers Based on Fluorene−Thieno[3,2-b]thiophene for Light-Emitting Diodes and Photovoltaic Cells , 2007 .

[22]  F. Krebs,et al.  Low band gap polymers for organic photovoltaics , 2007 .

[23]  A J Heeger,et al.  Efficiency enhancement in low-bandgap polymer solar cells by processing with alkane dithiols. , 2007, Nature materials.

[24]  Lenneke H. Slooff,et al.  Determining the internal quantum efficiency of highly efficient polymer solar cells through optical modeling , 2007 .

[25]  R. J. Kline,et al.  High Carrier Mobility Polythiophene Thin Films: Structure Determination by Experiment and Theory† , 2007 .

[26]  Ping Liu,et al.  Low-temperature, solution-processed, high-mobility polymer semiconductors for thin-film transistors. , 2007, Journal of the American Chemical Society.

[27]  K. Müllen,et al.  Field-effect transistors based on a benzothiadiazole-cyclopentadithiophene copolymer. , 2007, Journal of the American Chemical Society.

[28]  Xiaoniu Yang,et al.  Toward High-Performance Polymer Solar Cells: The Importance of Morphology Control , 2007 .

[29]  V. Shrotriya,et al.  Optimization of Narrow Band-Gap Propylenedioxythiophene:Cyanovinylene Copolymers for Optoelectronic Applications , 2006 .

[30]  Niyazi Serdar Sariciftci,et al.  Morphology of polymer/fullerene bulk heterojunction solar cells , 2006 .

[31]  Christoph J. Brabec,et al.  High Photovoltaic Performance of a Low‐Bandgap Polymer , 2006 .

[32]  J. Reynolds,et al.  Soluble narrow band gap and blue propylenedioxythiophene-cyanovinylene polymers as multifunctional materials for photovoltaic and electrochromic applications. , 2006, Journal of the American Chemical Society.

[33]  M. Leclerc,et al.  Synthesis of 2,7‐Carbazolenevinylene‐Based Copolymers and Characterization of Their Photovoltaic Properties , 2006 .

[34]  Xianyu Deng,et al.  Photocurrent response wavelength up to 1.1μm from photovoltaic cells based on narrow-band-gap conjugated polymer and fullerene derivative , 2006 .

[35]  A. Facchetti,et al.  Dithienosilole- and dibenzosilole-thiophene copolymers as semiconductors for organic thin-film transistors. , 2006, Journal of the American Chemical Society.

[36]  Mm Martijn Wienk,et al.  Low band gap polymer bulk heterojunction solar cells , 2006 .

[37]  Mm Martijn Wienk,et al.  Low-band gap poly(di-2-thienylthienopyrazine):fullerene solar cells , 2006 .

[38]  Maxim Shkunov,et al.  Liquid-crystalline semiconducting polymers with high charge-carrier mobility , 2006, Nature materials.

[39]  Mats Andersson,et al.  Influence of Solvent Mixing on the Morphology and Performance of Solar Cells Based on Polyfluorene Copolymer/Fullerene Blends , 2006 .

[40]  Christoph J. Brabec,et al.  Design Rules for Donors in Bulk‐Heterojunction Solar Cells—Towards 10 % Energy‐Conversion Efficiency , 2006 .

[41]  Donal D. C. Bradley,et al.  A strong regioregularity effect in self-organizing conjugated polymer films and high-efficiency polythiophene:fullerene solar cells , 2006 .

[42]  G. Wegner,et al.  Effect of Molecular Weight on the Structure and Crystallinity of Poly(3-hexylthiophene) , 2006 .

[43]  Yang Yang,et al.  High-efficiency solution processable polymer photovoltaic cells by self-organization of polymer blends , 2005 .

[44]  Xiong Gong,et al.  Thermally Stable, Efficient Polymer Solar Cells with Nanoscale Control of the Interpenetrating Network Morphology , 2005 .

[45]  David L. Carroll,et al.  High-efficiency photovoltaic devices based on annealed poly(3-hexylthiophene) and 1-(3-methoxycarbonyl)-propyl-1- phenyl-(6,6)C61 blends , 2005 .

[46]  J. Reynolds,et al.  Spectral Broadening in MEH-PPV:PCBM-Based Photovoltaic Devices via Blending with a Narrow Band Gap Cyanovinylene−Dioxythiophene Polymer , 2005 .

[47]  V. Mihailetchi,et al.  Space-charge limited photocurrent. , 2005, Physical review letters.

[48]  Donal D. C. Bradley,et al.  Device annealing effect in organic solar cells with blends of regioregular poly(3-hexylthiophene) and soluble fullerene , 2005 .

[49]  Christoph J. Brabec,et al.  Production Aspects of Organic Photovoltaics and Their Impact on the Commercialization of Devices , 2005 .

[50]  Mats Andersson,et al.  The electronic states of polyfluorene copolymers with alternating donor-acceptor units. , 2004, The Journal of chemical physics.

[51]  A. Matzger,et al.  Alkyl-Substituted Thieno[3,2-b]thiophene Polymers and Their Dimeric Subunits , 2004 .

[52]  Mats Andersson,et al.  Low bandgap alternating polyfluorene copolymers in plastic photodiodes and solar cells , 2004 .

[53]  Mats Andersson,et al.  High‐Performance Polymer Solar Cells of an Alternating Polyfluorene Copolymer and a Fullerene Derivative , 2003 .

[54]  Takakazu Yamamoto π-Conjugated Polymers with Electronic and Optical Functionalities: Preparation by Organometallic Polycondensation, Properties, and Applications , 2002 .

[55]  A. Heeger Nobel Lecture: Semiconducting and metallic polymers: The fourth generation of polymeric materials* , 2001 .

[56]  H. Bässler,et al.  Calculation of excitonic properties of conjugated polymers using the Bethe-Salpeter equation , 2001 .

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

[58]  S. Jenekhe,et al.  Thiophene-Linked Polyphenylquinoxaline: A New Electron Transport Conjugated Polymer for Electroluminescent Devices , 1999 .

[59]  Paul Seidler,et al.  Direct Determination of the Exciton Binding Energy of Conjugated Polymers Using a Scanning Tunneling Microscope , 1998 .

[60]  D. M. Leeuw,et al.  Stability of n-type doped conducting polymers and consequences for polymeric microelectronic devices , 1997 .

[61]  J. Roncali Synthetic Principles for Bandgap Control in Linear pi-Conjugated Systems. , 1997, Chemical reviews.

[62]  Y. Yamashita,et al.  Design of Narrow-Bandgap Polymers. Syntheses and Properties of Monomers and Polymers Containing Aromatic-Donor and o-Quinoid-Acceptor Units , 1996 .

[63]  J. Roncali Conjugated poly(thiophenes): synthesis, functionalization, and applications , 1992 .

[64]  R. Silbey,et al.  Chain-length dependence of electronic and electrochemical properties of conjugated systems: polyacetylene, polyphenylene, polythiophene, and polypyrrole , 1983 .

[65]  J. Fréchet,et al.  Polymer-fullerene composite solar cells. , 2008, Angewandte Chemie.