The Impact of Driving Force on Electron Transfer Rates in Photovoltaic Donor–Acceptor Blends

The effect of acceptor energy level on electron transfer rate in blends of the polymer solar-cell material poly[[4,8-bis[(2-ethylhexyl)oxy]benzo[1,2-b:4,5-b']dithiophene-2,6-diyl][3-fluoro-2-[(2-ethylhexyl)carbonyl]thieno[3,4-b]thiophenediyl]] (PTB7) is studied using time-resolved fluorescence. Fast electron transfer in less than 2 ps is observed for a driving force between 0.2 and 0.6 eV and the electron transfer is slower outside this range. This dependence is described by Marcus theory with a reorganization energy of ≈0.4 eV.

[1]  H. Matsuzaki,et al.  Charge Separation and Recombination of Charge-Transfer Excitons in Donor–Acceptor Polymer Solar Cells , 2013 .

[2]  P. Blom,et al.  Trap‐Limited Exciton Diffusion in Organic Semiconductors , 2014, Advanced materials.

[3]  P. Shaw,et al.  Probing the nanoscale phase separation in binary photovoltaic blends of poly(3-hexylthiophene) and methanofullerene by energy transfer. , 2009, Dalton transactions.

[4]  Frédéric Laquai,et al.  Effect of morphology on ultrafast free carrier generation in polythiophene:fullerene organic solar cells. , 2010, Journal of the American Chemical Society.

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

[6]  Donal D. C. Bradley,et al.  The photovoltaic response in poly(p-phenylene vinylene) thin-film devices , 1994 .

[7]  W. Mammo,et al.  Electrochemical bandgaps of substituted polythiophenesElectronic supplementary information (ESI) available: cyclic voltammograms not given within the article. See http://www.rsc.org/suppdata/jm/b3/b301403g/ , 2003 .

[8]  E. Vauthey,et al.  Bimolecular photoinduced electron transfer beyond the diffusion limit: the Rehm-Weller experiment revisited with femtosecond time resolution. , 2014, Journal of the American Chemical Society.

[9]  Tak W. Kee,et al.  Vibrational coherence probes the mechanism of ultrafast electron transfer in polymer–fullerene blends , 2014, Nature Communications.

[10]  F. Krebs,et al.  Direct observation of sub-100 fs mobile charge generation in a polymer-fullerene film. , 2012, Physical review letters.

[11]  V. Arkhipov,et al.  Quenching of excitons in doped disordered organic semiconductors , 2004 .

[12]  T. Dewey.  Fractal analysis of proton exchange kinetics in lysozyme. , 1994, Proceedings of the National Academy of Sciences of the United States of America.

[13]  N. Kopidakis,et al.  Photovoltaic charge generation in organic semiconductors based on long-range energy transfer. , 2010, ACS nano.

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

[15]  A Shift from Diffusion Assisted to Energy Transfer Controlled Fluorescence Quenching in Polymer–Fullerene Photovoltaic Blends , 2012 .

[16]  K. Sumathy,et al.  A review and recent developments in photocatalytic water-splitting using TiO2 for hydrogen production , 2007 .

[17]  David F. Watson,et al.  Electron injection at dye-sensitized semiconductor electrodes. , 2005, Annual review of physical chemistry.

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

[19]  Florian S. U. Fischer,et al.  On the Efficiency of Charge Transfer State Splitting in Polymer:Fullerene Solar Cells , 2014, Advanced materials.

[20]  V. Sundström,et al.  Charge formation and transport in bulk-heterojunction solar cells based on alternating polyfluorene copolymers blended with fullerenes , 2006 .

[21]  I. Samuel,et al.  Charge Pair Dissociation and Recombination Dynamics in a P3HT–PC60BM Bulk Heterojunction , 2013 .

[22]  Christoph J. Brabec,et al.  Tracing photoinduced electron transfer process in conjugated polymer/fullerene bulk heterojunctions in real time , 2001 .

[23]  Thuc-Quyen Nguyen,et al.  Effect of thermal annealing on exciton diffusion in a diketopyrrolopyrrole derivative. , 2012, Physical chemistry chemical physics : PCCP.

[24]  Vidmantas Gulbinas,et al.  Excited state and charge photogeneration dynamics in conjugated polymers. , 2007, The journal of physical chemistry. B.

[25]  Aram Amassian,et al.  Efficient charge generation by relaxed charge-transfer states at organic interfaces. , 2014, Nature materials.

[26]  G. Cerullo,et al.  Hot exciton dissociation in polymer solar cells. , 2013, Nature materials.

[27]  Ifor D. W. Samuel,et al.  Determining the optimum morphology in high-performance polymer-fullerene organic photovoltaic cells , 2013, Nature Communications.

[28]  Garry Rumbles,et al.  An Optimal Driving Force for Converting Excitons into Free Carriers in Excitonic Solar Cells , 2012 .

[29]  G. Fleming,et al.  Rates of primary electron transfer in photosynthetic reaction centres and their mechanistic implications , 1988, Nature.

[30]  Rudolph A. Marcus,et al.  On the Theory of Oxidation‐Reduction Reactions Involving Electron Transfer. I , 1956 .

[31]  Luping Yu,et al.  Photovoltaic Function and Exciton/Charge Transfer Dynamics in a Highly Efficient Semiconducting Copolymer , 2014 .

[32]  A. Furube,et al.  Ultrafast Studies of Charge Generation in PCBM:P3HT Blend Films following Excitation of the Fullerene PCBM , 2009 .

[33]  Mats Andersson,et al.  Ultrafast photogeneration of inter-chain charge pairs in polythiophene films , 2000 .

[34]  Qiao Zheng,et al.  Enhancing the performance of P3HT:ICBA based polymer solar cells using LiF as electron collecting buffer layer and UV–ozone treated MoO3 as hole collecting buffer layer , 2013 .

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

[36]  J. M. Smith.  CHEMICAL KINETICS AND TRANSPORT RATES IN FLUID SOLID CATALYTIC REACTORS , 1973 .

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