Low bandgap semiconducting polymers for polymeric photovoltaics.

In order to develop high performance polymer solar cells (PSCs), full exploitation of the sun-irradiation from ultraviolet (UV) to near infrared (NIR) is one of the key factors to ensure high photocurrents and thus high efficiency. In this review, five of the effective design rules for approaching LBG semiconducting polymers with high molar absorptivity, suitable energy levels, high charge carrier mobility and high solubility in organic solvents are overviewed. These design stratagems include fused heterocycles for facilitating π-electron flowing along the polymer backbone, groups/atoms bridging adjacent rings for maintaining a high planarity, introduction of electron-withdrawing units for lowering the bandgap (Eg), donor-acceptor (D-A) copolymerization for narrowing Eg and 2-dimensional conjugation for broadened absorption and enhanced hole mobility. It has been demonstrated that LBG semiconducting polymers based on electron-donor units combined with strong electron-withdrawing units possess excellent electronic and optic properties, emerging as excellent candidates for efficient PSCs. While for ultrasensitive photodetectors (PDs), which have intensive applications in both scientific and industrial sectors, sensing from the UV to the NIR region is of critical importance. For polymer PDs, Eg as low as 0.8 eV has been obtained through a rational design stratagem, covering a broad wavelength range from the UV to the NIR region (1450 nm). However, the response time of the polymer PDs are severely limited by the hole mobility of LBG semiconducting polymers, which is significantly lower than those of the inorganic materials. Thus, further advancing the hole mobility of LBG semiconducting polymers is of equal importance as broadening the spectral response for approaching uncooled ultrasensitive broadband polymer PDs in the future study.

[1]  Tunable alkali halide lasers , 1975, Nature.

[2]  I. Moreels,et al.  Size-dependent optical properties of colloidal PbS quantum dots. , 2009, ACS nano.

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

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

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

[6]  O. Inganäs,et al.  A Conjugated Polymer for Near Infrared Optoelectronic Applications , 2007 .

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

[8]  Stephen R. Forrest,et al.  The path to ubiquitous and low-cost organic electronic appliances on plastic , 2004, Nature.

[9]  C. Ting,et al.  Low-bandgap poly(thiophene-phenylene-thiophene) derivatives with broaden absorption spectra for use in high-performance bulk-heterojunction polymer solar cells. , 2008, Journal of the American Chemical Society.

[10]  He Yan,et al.  Aggregation and morphology control enables multiple cases of high-efficiency polymer solar cells , 2014, Nature Communications.

[11]  John R. Reynolds,et al.  Dithienogermole as a fused electron donor in bulk heterojunction solar cells. , 2011, Journal of the American Chemical Society.

[12]  Stergios Logothetidis,et al.  Flexible organic electronic devices: Materials, process and applications , 2008 .

[13]  G. Namkoong,et al.  Device optimization in PCPDTBT:PCBM plastic solar cells , 2010 .

[14]  Yang Yang,et al.  Tandem polymer solar cells featuring a spectrally matched low-bandgap polymer , 2012, Nature Photonics.

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

[16]  Long Ye,et al.  Highly Efficient 2D-Conjugated Benzodithiophene-Based Photovoltaic Polymer with Linear Alkylthio Side Chain , 2014 .

[17]  J. Moon,et al.  High-Detectivity Polymer Photodetectors with Spectral Response from 300 nm to 1450 nm , 2009, Science.

[18]  Jie Zheng,et al.  Water-soluble CdTe quantum dots as an anode interlayer for solution-processed near infrared polymer photodetectors. , 2013, Nanoscale.

[19]  Dezhi Yang,et al.  Optimization of Solubility, Film Morphology and Photodetector Performance by Molecular Side‐Chain Engineering of Low‐Bandgap Thienothiadiazole‐Based Polymers , 2014 .

[20]  Guillermo C Bazan,et al.  Streamlined microwave-assisted preparation of narrow-bandgap conjugated polymers for high-performance bulk heterojunction solar cells. , 2009, Nature chemistry.

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

[22]  Yongfang Li,et al.  Single‐Junction Polymer Solar Cells Exceeding 10% Power Conversion Efficiency , 2015, Advanced materials.

[23]  Aram Amassian,et al.  Efficient inverted bulk-heterojunction solar cells from low-temperature processing of amorphous ZnO buffer layers , 2014 .

[24]  K. S. Narayan,et al.  Fill factor in organic solar cells , 2010 .

[25]  Christoph J. Brabec,et al.  Recombination and loss analysis in polythiophene based bulk heterojunction photodetectors , 2002 .

[26]  Qingfeng Dong,et al.  An Ultraviolet‐to‐NIR Broad Spectral Nanocomposite Photodetector with Gain , 2014 .

[27]  Pierre-Antoine Bouit,et al.  Organic photovoltaics: a chemical approach. , 2010, Chemical communications.

[28]  Luping Yu,et al.  Development of new semiconducting polymers for high performance solar cells. , 2009, Journal of the American Chemical Society.

[29]  Yongfang Li,et al.  Synthesis and Photovoltaic Properties of D–A Copolymers Based on Dithienosilole and Benzotriazole , 2011 .

[30]  Fei Huang,et al.  Inverted polymer solar cells with 8.4% efficiency by conjugated polyelectrolyte , 2012 .

[31]  M. Beard,et al.  Highly efficient multiple exciton generation in colloidal PbSe and PbS quantum dots. , 2005, Nano letters.

[32]  F. Huang,et al.  Water/alcohol soluble conjugated polymers for the interface engineering of highly efficient polymer light-emitting diodes and polymer solar cells. , 2015, Chemical communications.

[33]  Andrew C. Stuart,et al.  Fluorine substituents reduce charge recombination and drive structure and morphology development in polymer solar cells. , 2013, Journal of the American Chemical Society.

[34]  Yongfang Li,et al.  Alkyl chain engineering on a dithieno[3,2-b:2',3'-d]silole-alt-dithienylthiazolo[5,4-d]thiazole copolymer toward high performance bulk heterojunction solar cells. , 2011, Chemical communications.

[35]  Fujun Zhang,et al.  Trap-assisted photomultiplication polymer photodetectors obtaining an external quantum efficiency of 37,500%. , 2015, ACS applied materials & interfaces.

[36]  Bryan M. Wong,et al.  Bridgehead Imine Substituted Cyclopentadithiophene Derivatives: An Effective Strategy for Band Gap Control in Donor–Acceptor Polymers , 2012 .

[37]  Qingfeng Dong,et al.  A nanocomposite ultraviolet photodetector based on interfacial trap-controlled charge injection. , 2012, Nature nanotechnology.

[38]  Gianlorenzo Masini,et al.  Si based optoelectronics for communications , 2002 .

[39]  W. Li,et al.  Donor-acceptor conjugated polymer based on naphtho[1,2-c:5,6-c]bis[1,2,5]thiadiazole for high-performance polymer solar cells. , 2011, Journal of the American Chemical Society.

[40]  Ji Qi,et al.  Optimization of Broad-Response and High-Detectivity Polymer Photodetectors by Bandgap Engineering of Weak Donor-Strong Acceptor Polymers , 2015 .

[41]  Nicolas Chevalier,et al.  Work Function Tuning for High‐Performance Solution‐Processed Organic Photodetectors with Inverted Structure , 2013, Advanced materials.

[42]  Yang Yang,et al.  Silicon Atom Substitution Enhances Interchain Packing in a Thiophene‐Based Polymer System , 2010, Advanced materials.

[43]  Gang Li,et al.  Highly efficient solar cell polymers developed via fine-tuning of structural and electronic properties. , 2009, Journal of the American Chemical Society.

[44]  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.

[45]  Gang Li,et al.  Synthesis of a low band gap polymer and its application in highly efficient polymer solar cells. , 2009, Journal of the American Chemical Society.

[46]  Tianyu Meng,et al.  High-detectivity inverted near-infrared polymer photodetectors using cross-linkable conjugated polyfluorene as an electron extraction layer , 2014 .

[47]  J. Roncali,et al.  An efficient strategy towards small bandgap polymers: The rigidification of the π‐conjugated system , 1994 .

[48]  A. Heeger,et al.  The influence of binary processing additives on the performance of polymer solar cells. , 2014, Nanoscale.

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

[50]  Xiong Gong,et al.  Single-junction polymer solar cells with over 10% efficiency by a novel two-dimensional donor-acceptor conjugated copolymer. , 2015, ACS applied materials & interfaces.

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

[52]  Yang Yang,et al.  Bandgap and Molecular Level Control of the Low-Bandgap Polymers Based on 3,6-Dithiophen-2-yl-2,5-dihydropyrrolo[3,4-c]pyrrole-1,4-dione toward Highly Efficient Polymer Solar Cells , 2009 .

[53]  Yang Yang,et al.  Nanoparticle-assisted high photoconductive gain in composites of polymer and fullerene. , 2008, Nature nanotechnology.

[54]  Ye Tao,et al.  A thieno[3,4-c]pyrrole-4,6-dione-based copolymer for efficient solar cells. , 2010, Journal of the American Chemical Society.

[55]  Yang Yang,et al.  Toward Highly Sensitive Polymer Photodetectors by Molecular Engineering , 2015, Advanced materials.

[56]  Po-An Yang,et al.  Synthesis, characterization, and photovoltaic properties of a low-bandgap copolymer based on 2,1,3-benzooxadiazole. , 2011, Chemical communications.

[57]  J. Soole,et al.  InGaAs metal-semiconductor-metal photodetectors for long wavelength optical communications , 1991 .

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

[59]  Eric Mazur,et al.  Microstructured silicon photodetector , 2006 .

[60]  Richard H. Friend,et al.  The Dependence of Device Dark Current on the Active‐Layer Morphology of Solution‐Processed Organic Photodetectors , 2010 .

[61]  X. Duan,et al.  Plasmon resonance enhanced multicolour photodetection by graphene. , 2011, Nature communications.

[62]  Alan J. Heeger,et al.  Semiconducting Polymer Photodetectors with Electron and Hole Blocking Layers: High Detectivity in the Near-Infrared , 2010, Sensors.

[63]  Geert Brocks,et al.  Small Band Gap Semiconducting Polymers Made from Dye Molecules: Polysquaraines , 1996 .

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

[65]  Yongfang Li,et al.  Synthesis and Photovoltaic Properties of D–A Copolymers Based on Alkyl-Substituted Indacenodithiophene Donor Unit , 2011 .

[66]  Dezhi Yang,et al.  2,1,3-Benzothiadiazole-5,6-dicarboxylic imide based low-bandgap polymers for solution processed photodiode application , 2015 .

[67]  K. Menten,et al.  A star in a 15.2-year orbit around the supermassive black hole at the centre of the Milky Way , 2002, Nature.

[68]  Jianhui Hou,et al.  Application of Two-Dimensional Conjugated Benzo(1,2-b:4,5- b')dithiophene in Quinoxaline-Based Photovoltaic Polymers , 2012 .

[69]  Zhiyuan Xie,et al.  Novel NIR-absorbing conjugated polymers for efficient polymer solar cells: effect of alkyl chain length on device performance , 2009 .

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

[71]  Fujun Zhang,et al.  Highly sensitive polymer photodetectors with a broad spectral response range from UV light to the near infrared region , 2015 .

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

[73]  Larry R. Dalton,et al.  Donor-Acceptor Thiolated Polyenic Chromophores Exhibiting Large Optical Nonlinearity and Excellent Photostability , 2008 .

[74]  C. Winder,et al.  Low bandgap polymers for photon harvesting in bulk heterojunction solar cells , 2004 .

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

[76]  Martijn Lenes,et al.  Small Bandgap Polymers for Organic Solar Cells (Polymer Material Development in the Last 5 Years) , 2008 .

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

[78]  J. Roncali,et al.  Novel narrow bandgap polymers from sp3 carbon-bridged bithienyls: poly(4,4-ethylenedioxy-4H-cyclopenta[2,1-b;3,4-b′]dithiophene) , 1994 .

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

[80]  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.

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

[82]  James M. Tour,et al.  Alternating Donor/Acceptor Repeat Units in Polythiophenes. Intramolecular Charge Transfer for Reducing Band Gaps in Fully Substituted Conjugated Polymers , 1998 .

[83]  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 .

[84]  Jianhui Hou,et al.  Manipulating Backbone Structure to Enhance Low Band Gap Polymer Photovoltaic Performance , 2013 .

[85]  John R. Tumbleston,et al.  Absolute Measurement of Domain Composition and Nanoscale Size Distribution Explains Performance in PTB7:PC71BM Solar Cells , 2013 .

[86]  Sheng-Fu Horng,et al.  Polymer infrared photo-detector with high sensitivity up to 1100 nm , 2011 .

[87]  A. Jen,et al.  Significant Improved Performance of Photovoltaic Cells Made from a Partially Fluorinated Cyclopentadithiophene/Benzothiadiazole Conjugated Polymer , 2012 .

[88]  Jean Roncali,et al.  Molecular bulk heterojunctions: an emerging approach to organic solar cells. , 2009, Accounts of chemical research.

[89]  C. Ting,et al.  Thiophene/Phenylene/Thiophene-Based Low-Bandgap Conjugated Polymers for Efficient Near-Infrared Photovoltaic Applications , 2009 .

[90]  John R. Tumbleston,et al.  Understanding the Morphology of PTB7:PCBM Blends in Organic Photovoltaics , 2014 .

[91]  Zhaojun Li,et al.  Enhanced Photovoltaic Performance of Diketopyrrolopyrrole (DPP)- Based Polymers with Extended π Conjugation , 2013 .

[92]  Gang Li,et al.  For the Bright Future—Bulk Heterojunction Polymer Solar Cells with Power Conversion Efficiency of 7.4% , 2010, Advanced materials.

[93]  Jean-Luc Brédas,et al.  Influence of donor and acceptor substituents on the electronic characteristics of poly(paraphenylene vinylene) and poly(paraphenylene) , 1994 .

[94]  M. Green,et al.  Surface plasmon enhanced silicon solar cells , 2007 .

[95]  Norbert Koch,et al.  Organic electronic devices and their functional interfaces. , 2007, Chemphyschem : a European journal of chemical physics and physical chemistry.

[96]  Ling-I Hung,et al.  Low-bandgap conjugated polymer for high efficient photovoltaic applications. , 2010, Chemical communications.

[97]  X. Gong,et al.  High‐Performance Inverted Organic Photovoltaics with Over 1‐μm Thick Active Layers , 2014 .

[98]  Miao Xu,et al.  Enhanced power-conversion efficiency in polymer solar cells using an inverted device structure , 2012, Nature Photonics.

[99]  X. Gong,et al.  Solution-Processed High-Detectivity Near-Infrared Polymer Photodetectors Fabricated by a Novel Low-Bandgap Semiconducting Polymer , 2013 .

[100]  N. Koch,et al.  Fluorinated copolymer PCPDTBT with enhanced open-circuit voltage and reduced recombination for highly efficient polymer solar cells. , 2012, Journal of the American Chemical Society.

[101]  Guillermo C. Bazan,et al.  Improved Performance of Polymer Bulk Heterojunction Solar Cells Through the Reduction of Phase Separation via Solvent Additives , 2010, Advanced materials.

[102]  M. Ratner,et al.  Intermolecular charge transfer between heterocyclic oligomers. Effects of heteroatom and molecular packing on hopping transport in organic semiconductors. , 2005, Journal of the American Chemical Society.

[103]  Jianhui Hou,et al.  Efficient Polymer Solar Cells Based on Benzothiadiazole and Alkylphenyl Substituted Benzodithiophene with a Power Conversion Efficiency over 8% , 2013, Advanced materials.

[104]  Luping Yu,et al.  Effects of additives on the morphology of solution phase aggregates formed by active layer components of high-efficiency organic solar cells. , 2011, Journal of the American Chemical Society.

[105]  Jiyun Song,et al.  High performance inverted organic solar cells with solution processed Ga-doped ZnO as an interfacial electron transport layer , 2013 .

[106]  Ye Tao,et al.  Bulk heterojunction solar cells using thieno[3,4-c]pyrrole-4,6-dione and dithieno[3,2-b:2',3'-d]silole copolymer with a power conversion efficiency of 7.3%. , 2011, Journal of the American Chemical Society.

[107]  Y. H. Jang,et al.  Time-Dependent Density Functional Theory Study on Benzothiadiazole-Based Low-Band-Gap Fused-Ring Copolymers for Organic Solar Cell Applications , 2011 .

[108]  O. Inganäs,et al.  Enhanced Photocurrent Spectral Response in Low‐Bandgap Polyfluorene and C70‐Derivative‐Based Solar Cells , 2005 .

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

[110]  G. Konstantatos,et al.  Solution-processed PbS quantum dot infrared photodetectors and photovoltaics , 2005, Nature materials.

[111]  Hadis Morkoç,et al.  High speed, low noise ultraviolet photodetectors based on GaN p-i-n and AlGaN(p)-GaN(i)-GaN(n)structures , 1997 .

[112]  Yongfang Li,et al.  A D-A copolymer of dithienosilole and a new acceptor unit of naphtho[2,3-c]thiophene-4,9-dione for efficient polymer solar cells. , 2011, Chemical communications.

[113]  A. Jen,et al.  Synthesis, Characterization, Charge Transport, and Photovoltaic Properties of Dithienobenzoquinoxaline- and Dithienobenzopyridopyrazine-Based Conjugated Polymers , 2011 .

[114]  Fei Huang,et al.  High-efficiency polymer solar cells via the incorporation of an amino-functionalized conjugated metallopolymer as a cathode interlayer. , 2013, Journal of the American Chemical Society.

[115]  Yongfang Li,et al.  Improvement of open-circuit voltage and photovoltaic properties of 2D-conjugated polymers by alkylthio substitution , 2014 .

[116]  Edward H. Sargent,et al.  Sensitive solution-processed visible-wavelength photodetectors , 2007 .

[117]  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 .

[118]  J. Rand,et al.  Silicon Nanowire Solar Cells , 2007 .

[119]  Meiyong Liao,et al.  Arbitrary Multicolor Photodetection by Hetero-integrated Semiconductor Nanostructures , 2013, Scientific Reports.

[120]  Yu-Shan Cheng,et al.  Single Junction Inverted Polymer Solar Cell Reaching Power Conversion Efficiency 10.31% by Employing Dual-Doped Zinc Oxide Nano-Film as Cathode Interlayer , 2014, Scientific Reports.

[121]  A. Heeger,et al.  Conductive Conjugated Polyelectrolyte as Hole‐Transporting Layer for Organic Bulk Heterojunction Solar Cells , 2014, Advanced materials.

[122]  S. Rawlings,et al.  A radio galaxy at redshift 4.41 , 1996, Nature.

[123]  J. Brédas,et al.  Relationship between band gap and bond length alternation in organic conjugated polymers , 1985 .

[124]  Alan J. Heeger,et al.  Recombination in polymer-fullerene bulk heterojunction solar cells , 2010 .

[125]  J. Springer,et al.  TCO and light trapping in silicon thin film solar cells , 2004 .

[126]  Yongfang Li,et al.  Synthesis and Characterization of a Copolymer Based on Thiazolothiazole and Dithienosilole for Polymer Solar Cells , 2011 .