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Even a little delocalization produces large kinetic enhancements of charge-separation efficiency in organic photovoltaics

In organic photovoltaics, charges can separate efficiently even if their Coulomb attraction is an order of magnitude greater than the available thermal energy. Delocalization has been suggested to explain this fact, because it could increase the initial separation of charges in the charge-transfer (...

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Autores principales: Balzer, Daniel, Kassal, Ivan
Formato: Online Artículo Texto
Lenguaje:English
Publicado: American Association for the Advancement of Science 2022
Materias:
Acceso en línea:https://www.ncbi.nlm.nih.gov/pmc/articles/PMC9374333/
https://www.ncbi.nlm.nih.gov/pubmed/35960797
http://dx.doi.org/10.1126/sciadv.abl9692
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author Balzer, Daniel
Kassal, Ivan
author_facet Balzer, Daniel
Kassal, Ivan
author_sort Balzer, Daniel
collection PubMed
description In organic photovoltaics, charges can separate efficiently even if their Coulomb attraction is an order of magnitude greater than the available thermal energy. Delocalization has been suggested to explain this fact, because it could increase the initial separation of charges in the charge-transfer (CT) state, reducing their attraction. However, understanding the mechanism requires a kinetic model of delocalized charge separation, which has proven difficult because it involves tracking the correlated quantum-mechanical motion of the electron and the hole in large simulation boxes required for disordered materials. Here, we report the first three-dimensional simulations of charge-separation dynamics in the presence of disorder, delocalization, and polaron formation, finding that even slight delocalization, across less than two molecules, can substantially enhance the charge-separation efficiency, even starting with thermalized CT states. Delocalization does not enhance efficiency by reducing the Coulomb attraction; instead, the enhancement is a kinetic effect produced by the increased overlap of electronic states.
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spelling pubmed-93743332022-08-18 Even a little delocalization produces large kinetic enhancements of charge-separation efficiency in organic photovoltaics Balzer, Daniel Kassal, Ivan Sci Adv Physical and Materials Sciences In organic photovoltaics, charges can separate efficiently even if their Coulomb attraction is an order of magnitude greater than the available thermal energy. Delocalization has been suggested to explain this fact, because it could increase the initial separation of charges in the charge-transfer (CT) state, reducing their attraction. However, understanding the mechanism requires a kinetic model of delocalized charge separation, which has proven difficult because it involves tracking the correlated quantum-mechanical motion of the electron and the hole in large simulation boxes required for disordered materials. Here, we report the first three-dimensional simulations of charge-separation dynamics in the presence of disorder, delocalization, and polaron formation, finding that even slight delocalization, across less than two molecules, can substantially enhance the charge-separation efficiency, even starting with thermalized CT states. Delocalization does not enhance efficiency by reducing the Coulomb attraction; instead, the enhancement is a kinetic effect produced by the increased overlap of electronic states. American Association for the Advancement of Science 2022-08-12 /pmc/articles/PMC9374333/ /pubmed/35960797 http://dx.doi.org/10.1126/sciadv.abl9692 Text en Copyright © 2022 The Authors, some rights reserved; exclusive licensee American Association for the Advancement of Science. No claim to original U.S. Government Works. Distributed under a Creative Commons Attribution NonCommercial License 4.0 (CC BY-NC). https://creativecommons.org/licenses/by-nc/4.0/This is an open-access article distributed under the terms of the Creative Commons Attribution-NonCommercial license (https://creativecommons.org/licenses/by-nc/4.0/) , which permits use, distribution, and reproduction in any medium, so long as the resultant use is not for commercial advantage and provided the original work is properly cited.
spellingShingle Physical and Materials Sciences
Balzer, Daniel
Kassal, Ivan
Even a little delocalization produces large kinetic enhancements of charge-separation efficiency in organic photovoltaics
title Even a little delocalization produces large kinetic enhancements of charge-separation efficiency in organic photovoltaics
title_full Even a little delocalization produces large kinetic enhancements of charge-separation efficiency in organic photovoltaics
title_fullStr Even a little delocalization produces large kinetic enhancements of charge-separation efficiency in organic photovoltaics
title_full_unstemmed Even a little delocalization produces large kinetic enhancements of charge-separation efficiency in organic photovoltaics
title_short Even a little delocalization produces large kinetic enhancements of charge-separation efficiency in organic photovoltaics
title_sort even a little delocalization produces large kinetic enhancements of charge-separation efficiency in organic photovoltaics
topic Physical and Materials Sciences
url https://www.ncbi.nlm.nih.gov/pmc/articles/PMC9374333/
https://www.ncbi.nlm.nih.gov/pubmed/35960797
http://dx.doi.org/10.1126/sciadv.abl9692
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