Elisa Collado-Fregoso, Silvina N. Pugliese, Mariusz Wojcik, Johannes Benduhn, Eyal Bar-Or, Lorena Perdigón-Toro, Ulrich Hörmann, Donato Spoltore, Koen Vandewal, Justin M. Hodgkiss, Dieter Neher
- The involvement of charge-transfer (CT) states in the photogeneration and recombination of charge carriers has been an important focus of study within the organic photovoltaic community. In this work, we investigate the molecular factors determining the mechanism of photocurrent generation in low-donor-content organic solar cells, where the active layer is composed of vacuum-deposited C-60 and small amounts of organic donor molecules. We find a pronounced decline of all photovoltaic parameters with decreasing CT state energy. Using a combination of steady-state photocurrent measurements and time-delayed collection field experiments, we demonstrate that the power conversion efficiency, and more specifically, the fill factor of these devices, is mainly determined by the bias dependence of photocurrent generation. By combining these findings with the results from ultrafast transient absorption spectroscopy, we show that blends with small CT energies perform poorly because of an increased nonradiative CT state decay rate and that thisThe involvement of charge-transfer (CT) states in the photogeneration and recombination of charge carriers has been an important focus of study within the organic photovoltaic community. In this work, we investigate the molecular factors determining the mechanism of photocurrent generation in low-donor-content organic solar cells, where the active layer is composed of vacuum-deposited C-60 and small amounts of organic donor molecules. We find a pronounced decline of all photovoltaic parameters with decreasing CT state energy. Using a combination of steady-state photocurrent measurements and time-delayed collection field experiments, we demonstrate that the power conversion efficiency, and more specifically, the fill factor of these devices, is mainly determined by the bias dependence of photocurrent generation. By combining these findings with the results from ultrafast transient absorption spectroscopy, we show that blends with small CT energies perform poorly because of an increased nonradiative CT state decay rate and that this decay obeys an energy-gap law. Our work challenges the common view that a large energy offset at the heterojunction and/or the presence of fullerene clusters guarantee efficient CT dissociation and rather indicates that charge generation benefits from high CT state energies through a slower decay to the ground state.…
MetadatenAuthor details: | Elisa Collado-FregosoORCiD, Silvina N. Pugliese, Mariusz WojcikORCiD, Johannes BenduhnORCiD, Eyal Bar-Or, Lorena Perdigón-ToroORCiDGND, Ulrich HörmannORCiDGND, Donato SpoltoreORCiD, Koen VandewalORCiD, Justin M. HodgkissORCiD, Dieter NeherORCiDGND |
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DOI: | https://doi.org/10.1021/jacs.8b09820 |
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ISSN: | 0002-7863 |
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Pubmed ID: | https://pubmed.ncbi.nlm.nih.gov/30620190 |
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Title of parent work (English): | Journal of the American Chemical Society |
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Subtitle (English): | the case of low-donor-content blends |
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Publisher: | American Chemical Society |
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Place of publishing: | Washington |
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Publication type: | Article |
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Language: | English |
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Date of first publication: | 2019/02/13 |
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Publication year: | 2019 |
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Release date: | 2021/04/08 |
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Volume: | 141 |
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Issue: | 6 |
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Number of pages: | 13 |
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First page: | 2329 |
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Last Page: | 2341 |
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Funding institution: | German Ministry of Science and Education (BMBF)Federal Ministry of Education & Research (BMBF) [FKZ 13N13719]; Deutsche Forschungsgemeinschaft (DFG)German Research Foundation (DFG) [182087777-SFB 951]; New Zealand Ministry of Business, Innovation, and Employment, via a Catalyst grant; BMBFFederal Ministry of Education & Research (BMBF) [03IPT602X] |
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Organizational units: | Mathematisch-Naturwissenschaftliche Fakultät / Institut für Physik und Astronomie |
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DDC classification: | 5 Naturwissenschaften und Mathematik / 53 Physik / 530 Physik |
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Peer review: | Referiert |
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