Effect of Nanocrystalline Domains in Photovoltaic Devices with Benzodithiophene-Based Donor–Acceptor Copolymers

We have investigated the effects of thin-film morphology on the photovolatic performance for a series of donor–acceptor copolymers based on benzodithiophene donor and benzothiadiazole acceptor units. Photovoltaic devices incorporating polymer:fullerene blends show highest efficiencies (up to 6%) for those polymers exhibiting the least degree of crystallinity in X-ray diffraction patterns and a corresponding lowest surface roughness in thin films. We find that the existence of such crystalline domains in thin polymer films correlates well with spectral signatures of polymer chain aggregates already present in solution prior to casting of the film. Polymer solubility and casting conditions therefore appear to be crucial factors for enhancing efficiencies of photovoltaic devices based on such donor–acceptor copolymers. To examine why the presence of crystallite domains lowers device efficiencies, we measured exciton diffusion lengths by modeling the time-dependent photoluminescence from thin polymer films de...

[1]  P. Blom,et al.  Systematic study of exciton diffusion length in organic semiconductors by six experimental methods , 2014 .

[2]  Gonzalo Santoro,et al.  A Direct Evidence of Morphological Degradation on a Nanometer Scale in Polymer Solar Cells , 2013, Advanced materials.

[3]  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.

[4]  Andrew C. Stuart,et al.  Fluorinated Polymer Yields High Organic Solar Cell Performance for a Wide Range of Morphologies , 2013 .

[5]  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.

[6]  O. Inganäs,et al.  Conformational Disorder Enhances Solubility and Photovoltaic Performance of a Thiophene–Quinoxaline Copolymer , 2013 .

[7]  Jean Manca,et al.  Effect of Polymer Crystallinity in P3HT:PCBM Solar Cells on Band Gap Trap States and Apparent Recombination Order , 2013 .

[8]  C. Ha,et al.  Poly(3-hexylthiophene-co-benzothiadiazole) (THBT) as an electron-accepting polymer for normal and inverted type all-polymer solar cells , 2013 .

[9]  Thomas D Anthopoulos,et al.  Fused dithienogermolodithiophene low band gap polymers for high-performance organic solar cells without processing additives. , 2013, Journal of the American Chemical Society.

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

[11]  Michael D. Barnes,et al.  Optical Probes of Chain Packing Structure and Exciton Dynamics in Polythiophene Films, Composites, and Nanostructures , 2012 .

[12]  F. Spano,et al.  Interplay between intrachain and interchain interactions in semiconducting polymer assemblies: the HJ-aggregate model. , 2012, The Journal of chemical physics.

[13]  Jenny Nelson,et al.  Effect of multiple adduct fullerenes on microstructure and phase behavior of P3HT:fullerene blend films for organic solar cells. , 2012, ACS nano.

[14]  Mauro Morana,et al.  Exciton diffusion length in narrow bandgap polymers , 2012 .

[15]  M. Gazzano,et al.  Anisotropic molecular packing of soluble C60 fullerenes in hexagonal nanocrystals obtained by solvent vapor annealing , 2012 .

[16]  G. Frey,et al.  On the Origin of Charge Generation in Hybrid TiOx/Conjugated Polymer Photovoltaic Devices , 2012 .

[17]  Alberto Salleo,et al.  Morphology‐Dependent Trap Formation in High Performance Polymer Bulk Heterojunction Solar Cells , 2011 .

[18]  Jukka Hast,et al.  Gravure printed flexible organic photovoltaic modules , 2011 .

[19]  P. Adriaensens,et al.  Description of the nanostructured morphology of [6,6]‐phenyl‐C61‐butyric acid methyl ester (PCBM) by XRD, DSC and solid‐state NMR , 2011, Magnetic resonance in chemistry : MRC.

[20]  P. Adriaensens,et al.  Solid-state NMR as a tool to describe and quantify the morphology of photoactive layers used in plastic solar cells , 2011 .

[21]  Luping Yu,et al.  When Function Follows Form: Effects of Donor Copolymer Side Chains on Film Morphology and BHJ Solar Cell Performance , 2010, Advanced materials.

[22]  Peyman Servati,et al.  Effects of annealing and degradation on regioregular polythiophene-based bulk heterojunction organic photovoltaic devices , 2010 .

[23]  M. Johnston,et al.  The role of ultrafast torsional relaxation in the emission from polythiophene aggregates , 2010, 2010 Conference on Optoelectronic and Microelectronic Materials and Devices.

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

[25]  Wei You,et al.  A weak donor-strong acceptor strategy to design ideal polymers for organic solar cells. , 2010, ACS applied materials & interfaces.

[26]  H. Ohkita,et al.  Charge generation and recombination dynamics in poly(3-hexylthiophene)/fullerene blend films with different regioregularities and morphologies. , 2010, Journal of the American Chemical Society.

[27]  U. Jeng,et al.  Morphologies of Self-Organizing Regioregular Conjugated Polymer/Fullerene Aggregates in Thin Film Solar Cells , 2010 .

[28]  A. Jen,et al.  A Simple and Effective Way of Achieving Highly Efficient and Thermally Stable Bulk-Heterojunction Polymer Solar Cells Using Amorphous Fullerene Derivatives as Electron Acceptor , 2009 .

[29]  Jea-Gun Park,et al.  Effect of interface thickness on power conversion efficiency of polymer photovoltaic cells , 2009 .

[30]  Bumjoon J. Kim,et al.  The influence of poly(3-hexylthiophene) regioregularity on fullerene-composite solar cell performance. , 2008, Journal of the American Chemical Society.

[31]  I. Samuel,et al.  Exciton Diffusion Measurements in Poly(3‐hexylthiophene) , 2008 .

[32]  T. Swager,et al.  Fluorescent Conjugated Polymers That Incorporate Substituted 2,1,3-Benzooxadiazole and 2,1,3-Benzothiadiazole Units , 2008 .

[33]  Claudia N. Hoth,et al.  High Photovoltaic Performance of Inkjet Printed Polymer:Fullerene Blends , 2007 .

[34]  J. Fréchet,et al.  Long‐Range Resonant Energy Transfer for Enhanced Exciton Harvesting for Organic Solar Cells , 2007 .

[35]  Gang Li,et al.  “Solvent Annealing” Effect in Polymer Solar Cells Based on Poly(3‐hexylthiophene) and Methanofullerenes , 2007 .

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

[37]  J. Nunzi,et al.  High Molecular Weights, Polydispersities, and Annealing Temperatures in the Optimization of Bulk‐Heterojunction Photovoltaic Cells Based on Poly(3‐hexylthiophene) or Poly(3‐butylthiophene) , 2006 .

[38]  Xiaoniu Yang,et al.  The formation of crystalline P3HT fibrils upon annealing of a PCBM:P3HT bulk heterojunction , 2006 .

[39]  Ping Liu,et al.  Synthesis and Thin-Film Transistor Performance of Poly(4,8-didodecylbenzo[1,2-b:4,5-b‘]dithiophene) , 2006 .

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

[41]  Jonathan M. Ziebarth,et al.  Enhanced Hole Mobility in Regioregular Polythiophene Infiltrated in Straight Nanopores , 2005 .

[42]  Jurjen Wildeman,et al.  Simultaneous enhancement of charge transport and exciton diffusion in poly(p-phenylene vinylene) derivatives , 2005 .

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

[44]  Jan C Hummelen,et al.  Accurate measurement of the exciton diffusion length in a conjugated polymer using a heterostructure with a side-chain cross-linked fullerene layer. , 2005, The journal of physical chemistry. A.

[45]  Christoph J. Brabec,et al.  Influence of the molecular weight of poly(3-hexylthiophene) on the performance of bulk heterojunction solar cells , 2005 .

[46]  I. McCulloch,et al.  Microwave-assisted synthesis of polythiophenes via the Stille coupling , 2005 .

[47]  Henning Sirringhaus,et al.  Enhanced Mobility of Poly(3-hexylthiophene) Transistors by Spin-Coating from High-Boiling-Point Solvents , 2004 .

[48]  T. Forster.  Energiewanderung und Fluoreszenz , 2004, Naturwissenschaften.

[49]  Christoph J. Brabec,et al.  A low-bandgap semiconducting polymer for photovoltaic devices and infrared emitting diodes , 2002 .

[50]  Raj René Janssen,et al.  Synthesis and characterization of a low bandgap conjugated polymer for bulk heterojunction photovoltaic cells , 2001 .

[51]  Raj René Janssen,et al.  Low-bandgap polymer photovoltaic cells , 2001 .

[52]  Eva Harth,et al.  EXCITON DIFFUSION AND DISSOCIATION IN CONJUGATED POLYMER/FULLERENE BLENDS AND HETEROSTRUCTURES , 1999 .

[53]  V. Sundström,et al.  Resolving the radical cation formation from the lowest-excited singlet (S1) state of terthiophene in a TiO2–SiO2 hybrid polymer matrix , 1999 .

[54]  Benjamin J. Schwartz,et al.  Conjugated polymer aggregates in solution: Control of interchain interactions , 1999 .

[55]  J. Tour,et al.  Low Optical Bandgap Polythiophenes by an Alternating Donor/Acceptor Repeat Unit Strategy , 1997 .

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

[57]  Gustafson,et al.  Spatially and temporally resolved emission from aggregates in conjugated polymers. , 1996, Physical review. B, Condensed matter.

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

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

[60]  David Braun,et al.  Semiconducting polymer‐buckminsterfullerene heterojunctions: Diodes, photodiodes, and photovoltaic cells , 1993 .

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

[62]  M. Kasha,et al.  ENERGY TRANSFER MECHANISMS AND THE MOLECULAR EXCITON MODEL FOR MOLECULAR AGGREGATES. , 1963, Radiation research.

[63]  Th. Förster,et al.  Transfer Mechanisms of Electronic Excitation Energy , 1960 .

[64]  T. Főrster,et al.  10th Spiers Memorial Lecture. Transfer mechanisms of electronic excitation , 1959 .