Slow relaxation of photogenerated charge carriers boosts open-circuit voltage of organic solar cells
Among the parameters determining the efficiency of an organic solar cell, the open-circuit voltage (VOC) is the one with most room for improvement. Existing models for the description of VOC assume that photogenerated charge carriers are thermalized. Here, we demonstrate that quasi-equilibrium concept...
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| Main Authors: | , , , |
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| Format: | Article (Journal) |
| Language: | English |
| Published: |
October 5, 2021
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| In: |
The journal of physical chemistry letters
Year: 2021, Volume: 12, Issue: 40, Pages: 9874-9881 |
| ISSN: | 1948-7185 |
| DOI: | 10.1021/acs.jpclett.1c02235 |
| Online Access: | Verlag, lizenzpflichtig, Volltext: https://doi.org/10.1021/acs.jpclett.1c02235 Verlag, lizenzpflichtig, Volltext: https://pubs.acs.org/doi/10.1021/acs.jpclett.1c02235 
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| Author Notes: | Tanvi Upreti, Sebastian Wilken, Huotian Zhang, and Martijn Kemerink |
| Summary: | Among the parameters determining the efficiency of an organic solar cell, the open-circuit voltage (VOC) is the one with most room for improvement. Existing models for the description of VOC assume that photogenerated charge carriers are thermalized. Here, we demonstrate that quasi-equilibrium concepts cannot fully describe VOC of disordered organic devices. For two representative donor:acceptor blends, it is shown that VOC is actually 0.1−0.2 V higher than it would be if the system was in thermodynamic equilibrium. Extensive numerical modeling reveals that the excess energy is mainly due to incomplete relaxation in the disorder-broadened density of states. These findings indicate that organic solar cells work as nonequilibrium devices, in which part of the photon excess energy is harvested in the form of an enhanced VOC. |
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| Item Description: | Gesehen am 04.12.2021 |
| Physical Description: | Online Resource |
| ISSN: | 1948-7185 |
| DOI: | 10.1021/acs.jpclett.1c02235 |