Controlling nanoscale morphology in polymer photovoltaic devices

Summary Whilst inspiring significant academic interest, the maximum power conversion efficiencies achieved by polymer PVs under solar conditions (PCE; 6.10–6.77%), are not yet sufficient for the devices to become widely marketable. Therefore much current work in the area is focussed on raising device efficiencies as far as possible towards theoretically achievable levels. To this end, key strategies involve material design and synthesis, device processing, and methods for controlling the morphology of the active components. This review aims to highlight the importance of morphological design and control for highly efficient polymer PVs, to discuss strategies by which morphology can be controlled, and to outline some of the characterisation techniques vital to the understanding and optimisation of morphology in these materials.

[1]  E. W. Meijer,et al.  Two-dimensional charge transport in self-organized, high-mobility conjugated polymers , 1999, Nature.

[2]  Yun Zhao,et al.  Solvent-vapor treatment induced performance enhancement of poly(3-hexylthiophene):methanofullerene bulk-heterojunction photovoltaic cells , 2007 .

[3]  Helmut Neugebauer,et al.  Stabilization of the nanomorphology of polymer–fullerene “bulk heterojunction” blends using a novel polymerizable fullerene derivative , 2005 .

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

[5]  Christoph J. Brabec,et al.  Correlation Between Structural and Optical Properties of Composite Polymer/Fullerene Films for Organic Solar Cells , 2005 .

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

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

[8]  Richard H. Friend,et al.  Self‐Organized Photonic Structures in Polymer Light‐Emitting Diodes , 2004 .

[9]  A. Arias,et al.  Raman microscopy determination of phase composition in polyfluorene composites , 2001 .

[10]  Jean M. J. Fréchet,et al.  Amphiphilic Diblock Copolymer Compatibilizers and Their Effect on the Morphology and Performance of Polythiophene:Fullerene Solar Cells , 2006 .

[11]  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.

[12]  J. Loos,et al.  Nanoscale electrical characterization of semiconducting polymer blends by conductive atomic force microscopy (C-AFM). , 2006, Ultramicroscopy.

[13]  N. S. Sariciftci,et al.  Conjugated polymer-based organic solar cells. , 2007, Chemical reviews.

[14]  Long-range energy transfer of singlet and triplet excitations in dye-doped tris(phenylquinoxaline) , 2001 .

[15]  Roar R. Søndergaard,et al.  Advanced materials and processes for polymer solar cell devices , 2010 .

[16]  Yang Yang,et al.  Solvation-Induced Morphology Effects on the Performance of Polymer-Based Photovoltaic Devices , 2001 .

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

[18]  William R. Salaneck,et al.  Energy‐Level Alignment at Organic/Metal and Organic/Organic Interfaces , 2009 .

[19]  J. Hummelen,et al.  Polymer Photovoltaic Cells: Enhanced Efficiencies via a Network of Internal Donor-Acceptor Heterojunctions , 1995, Science.

[20]  P. Heremans,et al.  Strategies for increasing the efficiency of heterojunction organic solar cells: material selection and device architecture. , 2009, Accounts of chemical research.

[21]  Guillermo C Bazan,et al.  "Plastic" solar cells: self-assembly of bulk heterojunction nanomaterials by spontaneous phase separation. , 2009, Accounts of chemical research.

[22]  R. Segalman,et al.  Block Copolymers for Organic Optoelectronics , 2009 .

[23]  C. A. Walsh,et al.  Efficient photodiodes from interpenetrating polymer networks , 1995, Nature.

[24]  M. Thelakkat,et al.  Crystalline-crystalline donor-acceptor block copolymers. , 2008, Angewandte Chemie.

[25]  Daniel Moses,et al.  Photoinduced Carrier Generation in P3HT/PCBM Bulk Heterojunction Materials , 2008 .

[26]  M. Thelakkat,et al.  Microphase‐Separated Donor–Acceptor Diblock Copolymers: Influence of HOMO Energy Levels and Morphology on Polymer Solar Cells , 2007 .

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

[28]  B. Olsen,et al.  Nonlamellar Phases in Asymmetric Rod−Coil Block Copolymers at Increased Segregation Strengths , 2007 .

[29]  Donal D. C. Bradley,et al.  Mobility enhancement in conjugated polymer field-effect transistors through chain alignment in a liquid-crystalline phase , 2000 .

[30]  Gang Li,et al.  Effects of Solvent Mixtures on the Nanoscale Phase Separation in Polymer Solar Cells , 2008 .

[31]  Bernard Kippelen,et al.  Interface modification of ITO thin films: organic photovoltaic cells , 2003 .

[32]  C. S. Fuller,et al.  A New Silicon p‐n Junction Photocell for Converting Solar Radiation into Electrical Power , 1954 .

[33]  Donal D. C. Bradley,et al.  Polarized Luminescence from Oriented Molecular Materials , 1999 .

[34]  Bernard Kippelen,et al.  Efficient thin-film organic solar cells based on pentacene/C60 heterojunctions , 2004 .

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

[36]  P. Heremans,et al.  Nanoimprinted semiconducting polymer films with 50 nm features and their application to organic heterojunction solar cells , 2008, Nanotechnology.

[37]  M. Thelakkat,et al.  Nanostructures of n-Type Organic Semiconductor in a p-Type Matrix via Self-Assembly of Block Copolymers , 2004 .

[38]  Thuc‐Quyen Nguyen,et al.  Electronic Properties at Gold/Conjugated‐Polyelectrolyte Interfaces , 2009 .

[39]  Shinuk Cho,et al.  Effect of substituted side chain on donor-acceptor conjugated copolymers , 2008 .

[40]  Richard H. Friend,et al.  Vertically segregated polymer-blend photovoltaic thin-film structures through surface-mediated solution processing , 2002 .

[41]  Neil C. Greenham,et al.  A microscopic model for the behavior of nanostructured organic photovoltaic devices , 2007 .

[42]  R. Friend,et al.  Phase Separation in Polyfluorene-Based Conjugated Polymer Blends: Lateral and Vertical Analysis of Blend Spin-Cast Thin Films , 2004 .

[43]  G. Fredrickson,et al.  Block Copolymers—Designer Soft Materials , 1999 .

[44]  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.

[45]  C. McNeill,et al.  Evolution of the nanomorphology of photovoltaic polyfluorene blends: sub-100 nm resolution with x-ray spectromicroscopy , 2008, Nanotechnology.

[46]  Kazuhito Hashimoto,et al.  Morphological Stabilization of Polymer Photovoltaic Cells by Using Cross-Linkable Poly(3-(5-hexenyl)thiophene) , 2009 .

[47]  T. Emrick,et al.  Donor−Acceptor Poly(thiophene-block-perylene diimide) Copolymers: Synthesis and Solar Cell Fabrication , 2009 .

[48]  M. Ueda,et al.  Well-Controlled Synthesis of Block Copolythiophenes , 2008 .

[49]  J. Brédas,et al.  Molecular understanding of organic solar cells: the challenges. , 2009, Accounts of chemical research.

[50]  T. Kowalewski,et al.  Conducting Block Copolymers of Regioregular Poly(3‐hexylthiophene) and Poly(methacrylates): Electronic Materials with Variable Conductivities and Degrees of Interfibrillar Order , 2007 .

[51]  M. Stamm,et al.  Grafting of polyfluorene by surface-initiated Suzuki polycondensation. , 2009, Angewandte Chemie.

[52]  Max Shtein,et al.  Flexible conjugated polymer photovoltaic cells with controlled heterojunctions fabricated using nanoimprint lithography , 2007 .

[53]  J.K.J. van Duren,et al.  In‐Situ Compositional and Structural Analysis of Plastic Solar Cells , 2002 .

[54]  R. Mezzenga,et al.  Crystalline Diblock Conjugated Copolymers: Synthesis, Self-Assembly, and Microphase Separation of Poly(3-butylthiophene)-b-poly(3-octylthiophene) , 2009 .

[55]  Mukti Aryal,et al.  Imprinted large-scale high density polymer nanopillars for organic solar cells , 2008 .

[56]  Dieter Meissner,et al.  Optical constants of conjugated polymer/fullerene based bulk-heterojunction organic solar cells , 2002 .

[57]  T. Nishi,et al.  Transmission Electron Microtomography and Polymer Nanostructures , 2010 .

[58]  C. Tang.  Two‐layer organic photovoltaic cell , 1986 .

[59]  Gang Li,et al.  Control of the nanoscale crystallinity and phase separation in polymer solar cells , 2008 .

[60]  Shubin Liu,et al.  Donor-Acceptor Polymers Incorporating Alkylated Dithienylbenzothiadiazole for Bulk Heterojunction Solar Cells: Pronounced Effect of Positioning Alkyl Chains , 2010 .

[61]  C. Brabec,et al.  2.5% efficient organic plastic solar cells , 2001 .

[62]  U. Steiner,et al.  Influence of molecular weight on the solar cell performance of double-crystalline donor-acceptor block copolymers , 2009 .

[63]  A. Tortschanoff,et al.  Site Torsional Motion and Dispersive Excitation Hopping Transfer in π-Conjugated Polymers† , 2000 .

[64]  Niyazi Serdar Sariciftci,et al.  Effects of Postproduction Treatment on Plastic Solar Cells , 2003 .

[65]  R. Hatton,et al.  Nanoimprinted large area heterojunction pentacene-C60 photovoltaic device , 2007 .

[66]  Xiaoniu Yang,et al.  Relating the Morphology of Poly(p‐phenylene vinylene)/Methanofullerene Blends to Solar‐Cell Performance , 2004 .

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

[68]  C. Frisbie,et al.  Nanoporous Poly(3-alkylthiophene) Thin Films Generated from Block Copolymer Templates , 2008 .

[69]  Xiaoniu Yang,et al.  Crystalline Organization of a Methanofullerene as Used for Plastic Solar‐Cell Applications , 2004 .

[70]  Xiaoniu Yang,et al.  Morphology and Thermal Stability of the Active Layer in Poly(p-phenylenevinylene)/Methanofullerene Plastic Photovoltaic Devices , 2004 .

[71]  Zhenan Bao,et al.  Soluble and processable regioregular poly(3‐hexylthiophene) for thin film field‐effect transistor applications with high mobility , 1996 .

[72]  C. McNeill,et al.  X-Ray Microscopy of Photovoltaic Polyfluorene Blends: Relating Nanomorphology to Device Performance , 2007 .

[73]  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 .

[74]  Sridhar Rajaram,et al.  Effect of Addition of a Diblock Copolymer on Blend Morphology and Performance of Poly(3-hexylthiophene):Perylene Diimide Solar Cells , 2009 .

[75]  Alan J. Heeger,et al.  Charge separation and photovoltaic conversion in polymer composites with internal donor/acceptor heterojunctions , 1995 .

[76]  R. Friend,et al.  Formation of nanopatterned polymer blends in photovoltaic devices. , 2010, Nano letters.

[77]  W. Huck,et al.  Surface‐Directed Phase Separation of Conjugated Polymer Blends for Efficient Light‐Emitting Diodes , 2008 .

[78]  G. Hadziioannou,et al.  Self-Assembling of Novel Fullerene-Grafted Donor–Acceptor Rod−Coil Block Copolymers , 2008 .

[79]  Ronn Andriessen,et al.  Disclosure of the nanostructure of MDMO-PPV:PCBM bulk hetero-junction organic solar cells by a combination of SPM and TEM , 2003 .

[80]  Stephen R. Forrest,et al.  Efficient bulk heterojunction photovoltaic cells using small-molecular-weight organic thin films , 2003, Nature.

[81]  R. Gaudiana,et al.  Stabilization of Film Morphology in Polymer‐Fullerene Heterojunction Solar Cells , 2004 .

[82]  Yang Yang,et al.  Regioregular copolymers of 3-alkoxythiophene and their photovoltaic application. , 2006, Journal of the American Chemical Society.

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

[84]  L. Balk,et al.  Conjugated triblock copolymers containing both electron-donor and electron-acceptor blocks , 2006 .

[85]  Dieter Meissner,et al.  Nanoscale Morphology of Conjugated Polymer/Fullerene‐Based Bulk‐ Heterojunction Solar Cells , 2004 .

[86]  Amy M. Ballantyne,et al.  Free Energy Control of Charge Photogeneration in Polythiophene/Fullerene Solar Cells: The Influence of Thermal Annealing on P3HT/PCBM Blends , 2008 .

[87]  Alan J. Heeger,et al.  Spatial Fourier‐Transform Analysis of the Morphology of Bulk Heterojunction Materials Used in “Plastic” Solar Cells , 2007 .