Charge carrier generation and transport in different stoichiometry APFO3:PC61BM solar cells.

In this paper we studied carrier drift dynamics in APFO3:PC61BM solar cells of varied stoichiometry (2:1, 1:1, and 1:4 APFO3:PC61BM) over a wide time range, from subpicoseconds to microseconds with a combination of ultrafast optical electric field probing and conventional transient integrated photocurrent techniques. Carrier drift and extraction dynamics are strongly stoichiometry dependent: the speed of electron or hole drift increases with higher concentration of PC61BM or polymer, respectively. The electron extraction from a sample with 80% PC61BM takes place during hundreds of picoseconds, but slows down to sub-microseconds in a sample with 33% PC61BM. The hole extraction is less stoichiometry dependent: it varies form sub-nanoseconds to tens of nanoseconds when the PC61BM concentration changes from 33% to 80%. The electron extraction rate correlates with the conversion efficiency of solar cells, leading to the conclusion that fast electron motion is essential for efficient charge carrier separation preventing their geminate recombination.

[1]  V. Sundström,et al.  Charge Carrier Dynamics of Polymer:Fullerene Blends: From Geminate to Non‐Geminate Recombination , 2014 .

[2]  R. Friend,et al.  Ultrafast Long-Range Charge Separation in Organic Semiconductor Photovoltaic Diodes , 2014, Science.

[3]  P. E. Keivanidis,et al.  Carrier motion in as-spun and annealed P3HT:PCBM blends revealed by ultrafast optical electric field probing and Monte Carlo simulations. , 2014, Physical chemistry chemical physics : PCCP.

[4]  C. Groves,et al.  Monte Carlo Simulation of Geminate Pair Recombination Dynamics in Organic Photovoltaic Devices: Multi-Exponential, Field-Dependent Kinetics and Its Interpretation , 2014 .

[5]  P. E. Keivanidis,et al.  Visualizing charge separation in bulk heterojunction organic solar cells , 2013, Nature Communications.

[6]  John R. Tumbleston,et al.  The Importance of Fullerene Percolation in the Mixed Regions of Polymer–Fullerene Bulk Heterojunction Solar Cells , 2013 .

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

[8]  U. Scherf,et al.  Mobility relaxation and electron trapping in a donor/acceptor copolymer , 2013 .

[9]  Martin A. Green,et al.  Solar cell efficiency tables (version 41) , 2013 .

[10]  V. Sundström,et al.  Insights into the Charge Carrier Terahertz Mobility in Polyfluorenes from Large-Scale Atomistic Simulations and Time-Resolved Terahertz Spectroscopy , 2012 .

[11]  V. Sundström,et al.  Electron and Hole Contributions to the Terahertz Photoconductivity of a Conjugated Polymer:Fullerene Blend Identified. , 2012, The journal of physical chemistry letters.

[12]  V. Sundström,et al.  Ultrafast terahertz photoconductivity of bulk heterojunction materials reveals high carrier mobility up to nanosecond time scale. , 2012, Journal of the American Chemical Society.

[13]  David Beljonne,et al.  The Role of Driving Energy and Delocalized States for Charge Separation in Organic Semiconductors , 2012, Science.

[14]  Olle Inganäs,et al.  Interlayer for Modified Cathode in Highly Efficient Inverted ITO‐Free Organic Solar Cells , 2012, Advanced materials.

[15]  Thomas Strobel,et al.  Role of polaron pair diffusion and surface losses in organic semiconductor devices. , 2010, Physical review letters.

[16]  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.

[17]  V. Sundström,et al.  Geminate charge recombination in polymer/fullerene bulk heterojunction films and implications for solar cell function. , 2010, Journal of the American Chemical Society.

[18]  D. Hertel,et al.  Ultrafast dynamics of carrier mobility in a conjugated polymer probed at molecular and microscopic length scales. , 2009, Physical review letters.

[19]  V. Sundström,et al.  Exciton dynamics in alternating polyfluorene/fullerene blends , 2008 .

[20]  Stefan C J Meskers,et al.  Compositional and electric field dependence of the dissociation of charge transfer excitons in alternating polyfluorene copolymer/fullerene blends. , 2008, Journal of the American Chemical Society.

[21]  P. Cunningham,et al.  Carrier Dynamics Resulting from Above and Below Gap Excitation of P3HT and P3HT/ PCBM Investigated by Optical-Pump Terahertz-Probe Spectroscopy , 2008 .

[22]  F. Castro,et al.  Poly(3-hexylthiophene)/C60 heterojunction solar cells: Implication of morphology on performance and ambipolar charge collection , 2008 .

[23]  J. Melinger,et al.  Terahertz mobility measurements on poly-3-hexylthiophene films: Device comparison, molecular weight, and film processing effects , 2008 .

[24]  O. Inganäs,et al.  Stoichiometry, mobility, and performance in bulk heterojunction solar cells , 2007 .

[25]  Olle Inganäs,et al.  Geminate charge recombination in alternating polyfluorene copolymer/fullerene blends. , 2007, Journal of the American Chemical Society.

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

[27]  S. Patil,et al.  High intra-chain hole mobility on molecular wires of ladder type poly(p-phenylenes) , 2006, SPIE Optics + Photonics.

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

[29]  G. Lanzani,et al.  Photoinduced transient stark spectroscopy in organic semiconductors: a method for charge mobility determination in the picosecond regime. , 2006, Physical review letters.

[30]  O. Inganäs,et al.  Acceptor influence on hole mobility in fullerene blends with alternating copolymers of fluorene , 2006 .

[31]  Donal D. C. Bradley,et al.  Ambipolar Charge Transport in Films of Methanofullerene and Poly(phenylenevinylene)/Methanofullerene Blends , 2005 .

[32]  S. Bauer,et al.  Fabrication and characterization of solution-processed methanofullerene-based organic field-effect transistors , 2005 .

[33]  P. Blom,et al.  Ambipolar Organic Field‐Effect Transistors Based on a Solution‐Processed Methanofullerene , 2004 .

[34]  V. Sundström,et al.  Ultrafast light-induced charge pair formation dynamics in poly[3-(2 '-methoxy-5 ' octylphenyl)thiophene] , 2004 .

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

[36]  J. Kroon,et al.  Mobility and decay kinetics of charge carriers in photoexcited PCBM/PPV blends , 2004 .

[37]  C. Brabec,et al.  Solution‐Processed Organic n‐Type Thin‐Film Transistors , 2003 .

[38]  E. van Veenendaal,et al.  Solution-processed ambipolar organic field-effect transistors and inverters , 2003, Nature materials.

[39]  Mm Martijn Wienk,et al.  Electron Transport in a Methanofullerene , 2003 .

[40]  D. Hertel,et al.  Exciton dissociation in conjugated polymers , 2004 .

[41]  V. Sundström,et al.  Dynamics of the electric field-assisted charge carrier photogeneration in ladder-type poly(para-phenylene) at a low excitation intensity. , 2002, Physical review letters.