Thiophene-Fused Benzothiadiazole: A Strong Electron-Acceptor Unit to Build D–A Copolymer for Highly Efficient Polymer Solar Cells

A novel strong electron-acceptor, thieno[2,3-f]-2,1,3-benzothiadiazole-6-carboxylate (BTT), was first designed and synthesized. By introducing two thienyl groups into BTT and then copolymerizing with thienyl group substituted benzo[1,2-b:4,5-b′]dithiophene (BDTT) unit, a low band gap D–A copolymer (PBTT-TBDTT) was obtained. Compared with its polymer analogue (PBT-TBDTT) with benzothiadiazole (BT) as an acceptor, PBTT-TBDTT exhibits stronger intramolecular charge transfer. Thus, it shows much broader absorption covering almost the whole visible light region (in the range of 300–850 nm) and narrower optical band gap around 1.45 eV with a large IP (ionization potential) at 5.35 eV. The maximum efficiency of PBTT-TBDTT based device reaches 6.07% which is much higher than that of PBT-TBDTT (3.24%), indicating that BTT unit is a promising electron-acceptor moiety to construct low band gap D–A copolymers for PSCs with high photovoltaic performances.

[1]  Chang Liu,et al.  Molecular weight effect on the efficiency of polymer solar cells. , 2013, ACS applied materials & interfaces.

[2]  Ning Wang,et al.  Fluorinated benzothiadiazole-based conjugated polymers for high-performance polymer solar cells without any processing additives or post-treatments. , 2013, Journal of the American Chemical Society.

[3]  T. Russell,et al.  Semi-crystalline random conjugated copolymers with panchromatic absorption for highly efficient polymer solar cells , 2013 .

[4]  M. Wienk,et al.  High-molecular-weight regular alternating diketopyrrolopyrrole-based terpolymers for efficient organic solar cells. , 2013, Angewandte Chemie.

[5]  A. Jen,et al.  Side-Chain Effect on Cyclopentadithiophene/Fluorobenzothiadiazole-Based Low Band Gap Polymers and Their Applications for Polymer Solar Cells , 2013 .

[6]  A. Amadei,et al.  Toward a Realistic Modeling of the Photophysics of Molecular Building Blocks for Energy Harvesting: The Charge-Transfer State in 4,7-Dithien-2-yl-2,1,3-benzothiadiazole As a Case Study , 2013 .

[7]  T. Koganezawa,et al.  Naphthodithiophene-naphthobisthiadiazole copolymers for solar cells: alkylation drives the polymer backbone flat and promotes efficiency. , 2013, Journal of the American Chemical Society.

[8]  Yun‐Hi Kim,et al.  N-Octyl-2,7-dithia-5-azacyclopenta[a]pentalene-4,6-dione-Based Low Band Gap Polymers for Efficient Solar Cells , 2013 .

[9]  J. Fréchet,et al.  Linear side chains in benzo[1,2-b:4,5-b']dithiophene-thieno[3,4-c]pyrrole-4,6-dione polymers direct self-assembly and solar cell performance. , 2013, Journal of the American Chemical Society.

[10]  Yang Yang,et al.  A polymer tandem solar cell with 10.6% power conversion efficiency , 2013, Nature Communications.

[11]  Q. Peng,et al.  Enhanced solar cell performance by replacing benzodithiophene with naphthodithiophene in diketopyrrolopyrrole-based copolymers. , 2012, Chemical communications.

[12]  Yongfang Li,et al.  Conjugated Side-Chain-Isolated D–A Copolymers Based on Benzo[1,2-b:4,5-b′]dithiophene-alt-dithienylbenzotriazole: Synthesis and Photovoltaic Properties , 2012 .

[13]  Weiwei Li,et al.  Enhancing the photocurrent in diketopyrrolopyrrole-based polymer solar cells via energy level control. , 2012, Journal of the American Chemical Society.

[14]  Yang Yang,et al.  Systematic investigation of benzodithiophene- and diketopyrrolopyrrole-based low-bandgap polymers designed for single junction and tandem polymer solar cells. , 2012, Journal of the American Chemical Society.

[15]  Jean-Luc Brédas,et al.  Synthetic principles directing charge transport in low-band-gap dithienosilole-benzothiadiazole copolymers. , 2012, Journal of the American Chemical Society.

[16]  Y. Dong,et al.  Synthesis of novel narrow-band-gap copolymers based on [1,2,5]thiadiazolo[3,4-f]benzotriazole and their application in bulk-heterojunction photovoltaic devices , 2012 .

[17]  K. Schanze,et al.  It takes more than an imine: the role of the central atom on the electron-accepting ability of benzotriazole and benzothiadiazole oligomers. , 2012, Journal of the American Chemical Society.

[18]  Yongfang Li.  Molecular design of photovoltaic materials for polymer solar cells: toward suitable electronic energy levels and broad absorption. , 2012, Accounts of chemical research.

[19]  Jean-Luc Brédas,et al.  A quantum-chemical perspective into low optical-gap polymers for highly-efficient organic solar cells , 2011 .

[20]  Yongfang Li,et al.  Sulfonyl: a new application of electron-withdrawing substituent in highly efficient photovoltaic polymer. , 2011, Chemical communications.

[21]  Cody W. Schlenker,et al.  The molecular nature of photovoltage losses in organic solar cells. , 2011, Chemical communications.

[22]  S. Mhaisalkar,et al.  Synthesis of low band gap [1,2,5]-thiadiazolo[3,4-g]quinoxaline and pyrazino[2,3-g]quinoxaline derivatives by selective reduction of benzo[1,2-c;4,5-c']bis[1,2,5]thiadiazole. , 2011, Organic letters.

[23]  Yang Yang,et al.  Polymer solar cells with enhanced open-circuit voltage and efficiency , 2009 .

[24]  Chain‐Shu Hsu,et al.  Synthesis of conjugated polymers for organic solar cell applications. , 2009, Chemical reviews.

[25]  William J. Potscavage,et al.  Critical interfaces in organic solar cells and their influence on the open-circuit voltage. , 2009, Accounts of chemical research.

[26]  Raj René Janssen,et al.  The Energy of Charge‐Transfer States in Electron Donor–Acceptor Blends: Insight into the Energy Losses in Organic Solar Cells , 2009 .

[27]  John R. Reynolds,et al.  A spray-processable, low bandgap, and ambipolar donor-acceptor conjugated polymer. , 2009, Journal of the American Chemical Society.

[28]  Luping Yu,et al.  Regioregular Oligomer and Polymer Containing Thieno[3,4-b]thiophene Moiety for Efficient Organic Solar Cells , 2009 .

[29]  Yang Yang,et al.  Synthesis, characterization, and photovoltaic properties of a low band gap polymer based on silole-containing polythiophenes and 2,1,3-benzothiadiazole. , 2008, Journal of the American Chemical Society.

[30]  Yang Yang,et al.  Bandgap and Molecular Energy Level Control of Conjugated Polymer Photovoltaic Materials Based on Benzo[1,2-b:4,5-b']dithiophene , 2008 .

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

[32]  Jean-Luc Brédas,et al.  Charge transport in organic semiconductors. , 2007, Chemical reviews.

[33]  Paulo F. Moreira,et al.  Are Molecular 5,8‐π‐Extended Quinoxaline Derivatives Good Chromophores for Photoluminescence Applications? , 2006 .

[34]  Mats Andersson,et al.  An alternating low band-gap polyfluorene for optoelectronic devices , 2006 .

[35]  Frederik C. Krebs,et al.  Low-band-gap conjugated polymers based on thiophene, benzothiadiazole, and benzobis (thiadiazole) , 2006 .

[36]  David Beljonne,et al.  Charge-transfer and energy-transfer processes in pi-conjugated oligomers and polymers: a molecular picture. , 2004, Chemical reviews.

[37]  F. Wudl,et al.  A Robust Low Band Gap Processable n-Type Conducting Polymer Based on Poly(isothianaphthene) , 2001 .

[38]  Alan J. Heeger,et al.  Towards organic polymers with very small intrinsic band gaps. I. Electronic structure of polyisothianaphthene and derivatives , 1986 .

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