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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Atomistic Approach To Simulate Processes Relevant for the Efficiencies of Organic Solar Cells as a Function of Molecular Properties. II. Kinetic Aspects
TL;DR: In this paper, the individual steps of the light-to-energy conversion process in the vicinity of the interfaces of organic solar cells are investigated with kinetic Monte Carlo simulations employing Marcus hopping rates obtained from quantum-chemical calculations.
Journal ArticleDOI
Two-photon absorption arises from two-dimensional excitons.
TL;DR: By applying quantum perturbation theory to two-dimensional excitons in monolayer transition metal dichalcogenides (TMDCs), this work develops a theoretical model for two-photon absorption in the near infrared spectral region.
Journal ArticleDOI
Resonance Raman overtones reveal vibrational displacements and dynamics of crystalline and amorphous poly(3-hexylthiophene) chains in fullerene blends
Jian Gao,John K. Grey +1 more
TL;DR: The results demonstrate the potential of simpler CW resonance Raman approaches to uncover excited state geometry changes and early vibrational dynamics from distinct morphological forms in polymer∕fullerene blends.
Journal ArticleDOI
Computational modelling of donor–acceptor conjugated polymers through engineered backbone manipulations based on a thiophene–quinoxaline alternating copolymer
TL;DR: In this article, the authors performed a density functional theory (DFT) study on the heteroatom effects of combining fluorine, nitrogen and chalcogen substitutions onto the donor/acceptor units as well as the effect of extending π-conjugation in the donor moiety.
Journal ArticleDOI
A stereoregular β-dicyanodistyrylbenzene (β-DCS)-based conjugated polymer for high-performance organic solar cells with small energy loss and high quantum efficiency
Jun-Mo Park,Dongwon Kim,Hae Yeon Chung,Ji Eon Kwon,Seung Hwa Hong,Tae-Lim Choi,Soo Young Park +6 more
TL;DR: In this article, a new stereoregular β-dicyanodistyrylbenzene (β-DCS)-based polymer (PBDCS), consisting of trans-isomeric β-DCS and two-dimensional benzodithiophene (2D-BDT), was presented.
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.