Journal ArticleDOI
Hot exciton dissociation in polymer solar cells
Giulia Grancini,Margherita Maiuri,Daniele Fazzi,Annamaria Petrozza,H.-J. Egelhaaf,Daniele Brida,Giulio Cerullo,Guglielmo Lanzani,Guglielmo Lanzani +8 more
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TLDR
This work directly targets the interfacial physics of an efficient low-bandgap polymer/PC(60)BM system and rationalizes these findings in terms of a higher degree of delocalization of the hot CTSs with respect to the relaxed ones, which enhances the probability of charge dissociation in the first 200 fs.Abstract:
The standard picture of photovoltaic conversion in all-organic bulk heterojunction solar cells predicts that the initial excitation dissociates at the donor/acceptor interface after thermalization. Accordingly, on above-gap excitation, the excess photon energy is quickly lost by internal dissipation. Here we directly target the interfacial physics of an efficient low-bandgap polymer/PC(60)BM system. Exciton splitting occurs within the first 50 fs, creating both interfacial charge transfer states (CTSs) and polaron species. On high-energy excitation, higher-lying singlet states convert into hot interfacial CTSs that effectively contribute to free-polaron generation. We rationalize these findings in terms of a higher degree of delocalization of the hot CTSs with respect to the relaxed ones, which enhances the probability of charge dissociation in the first 200 fs. Thus, the hot CTS dissociation produces an overall increase in the charge generation yield.read more
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Charge carrier recombination in organic solar cells
TL;DR: In this paper, the authors review the latest on geminate and nongeminate recombination in organic solar cells and discuss the key loss mechanisms in charge carrier recombination, which is one of the most promising alternative energy sources because of their ease of processing and their potential to be produced using large scale techniques such as roll-to-roll, newspaper style, coating.
Journal ArticleDOI
Additives for morphology control in high-efficiency organic solar cells
Hsueh-Chung Liao,Chun-Chih Ho,Chih Yu Chang,Meng Huan Jao,Seth B. Darling,Seth B. Darling,Wei-Fang Su +6 more
TL;DR: In this article, a review of morphological control of bulk heterojunction photovoltaics with solvent additives is presented, including material selection, morphological variations at various length scales and interpretations of the interaction among additives and BHJ materials.
Journal ArticleDOI
Coherent ultrafast charge transfer in an organic photovoltaic blend
S. M. Falke,Carlo Andrea Rozzi,Daniele Brida,Daniele Brida,Margherita Maiuri,Michele Amato,Ephraim Sommer,Antoinietta De Sio,Angel Rubio,Giulio Cerullo,Elisa Molinari,Christoph Lienau +11 more
TL;DR: The results show that coherent vibronic coupling between electronic and nuclear degrees of freedom is of key importance in triggering charge delocalization and transfer in a noncovalently bound reference system.
Journal ArticleDOI
Light Harvesting for Organic Photovoltaics
TL;DR: The fundamental processes in photovoltaic devices are described, with the main emphasis on the characterization of energy transfer and its role in dictating device architecture, including multilayer planar heterojunctions, and on the factors that impact free carrier generation from dissociated excitons.
Journal ArticleDOI
Efficient organic solar cells with helical perylene diimide electron acceptors.
Yu Zhong,M. Tuan Trinh,Rongsheng Chen,Rongsheng Chen,Wei Wang,Petr P. Khlyabich,Bharat Kumar,Qizhi Xu,Chang-Yong Nam,Matthew Y. Sfeir,Charles T. Black,Michael L. Steigerwald,Yueh-Lin Loo,Shengxiong Xiao,Fay Ng,Xiaoyang Zhu,Colin Nuckolls,Colin Nuckolls +17 more
TL;DR: Femtosecond transient absorption spectroscopy revealed both electron and hole transfer processes at the donor-acceptor interfaces, indicating that charge carriers are created from photogenerated excitons in both the electron donor and acceptor phases.
References
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Journal ArticleDOI
Efficiency enhancement in low-bandgap polymer solar cells by processing with alkane dithiols
Jeff Peet,Jin Young Kim,Nelson E. Coates,Wanli Ma,Daniel Moses,Alan J. Heeger,Guillermo C. Bazan +6 more
TL;DR: By incorporating a few volume per cent of alkanedithiols in the solution used to spin-cast films comprising a low-bandgap polymer and a fullerene derivative, the power-conversion efficiency of photovoltaic cells is increased from 2.8% to 5.5% through altering the bulk heterojunction morphology.
Journal ArticleDOI
Charge Photogeneration in Organic Solar Cells
TL;DR: The backbone of a π-conjugated polymer is comprised of a linear series of overlapping pz orbitals that have formed via sp2 hybridization, thereby creating a conjugated chain of delocalized electron density, which dictates the electronic characteristics of the polymer.
Journal ArticleDOI
Molecular Understanding of Organic Solar Cells: The Challenges
Jean-Luc Brédas,Jean-Luc Brédas,Joseph E. Norton,Jérôme Cornil,Jérôme Cornil,Veaceslav Coropceanu +5 more
TL;DR: An overview of the optical and electronic processes that take place in a solid-state organic solar cell, which is defined as a cell in which the semiconducting materials between the electrodes are organic.
Journal ArticleDOI
The Role of Driving Energy and Delocalized States for Charge Separation in Organic Semiconductors
Artem A. Bakulin,Akshay Rao,V.G. Pavelyev,Paul H. M. van Loosdrecht,Maxim S. Pshenichnikov,Dorota Niedzialek,Jérôme Cornil,David Beljonne,Richard H. Friend +8 more
TL;DR: In this paper, the electron-hole pair created via photon absorption in organic photoconversion systems must overcome the Coulomb attraction to achieve long-range charge separation, and this process is facilitated through the formation of excited, delocalized band states.
Journal ArticleDOI
Fullerene crystallisation as a key driver of charge separation in polymer/fullerene bulk heterojunction solar cells
Fiona C. Jamieson,Ester Buchaca Domingo,Thomas McCarthy-Ward,Martin Heeney,Natalie Stingelin,Natalie Stingelin,James R. Durrant +6 more
TL;DR: In this article, the formation of a relatively pure, molecularly ordered phase of the fullerene component, phenyl-C61-butyric acid methyl ester (PCBM), may be the key factor driving the spatial separation of photogenerated electrons and holes in many organic solar cells.