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Decoding charge recombination through charge generation in organic solar cells
- The in‐depth understanding of charge carrier photogeneration and recombination mechanisms in organic solar cells is still an ongoing effort. In donor:acceptor (bulk) heterojunction organic solar cells, charge photogeneration and recombination are inter‐related via the kinetics of charge transfer states—being singlet or triplet states. Although high‐charge‐photogeneration quantum yields are achieved in many donor:acceptor systems, only very few systems show significantly reduced bimolecular recombination relative to the rate of free carrier encounters, in low‐mobility systems. This is a serious limitation for the industrialization of organic solar cells, in particular when aiming at thick active layers. Herein, a meta‐analysis of the device performance of numerous bulk heterojunction organic solar cells is presented for which field‐dependent photogeneration, charge carrier mobility, and fill factor are determined. Herein, a “spin‐related factor” that is dependent on the ratio of back electron transfer of the triplet charge transferThe in‐depth understanding of charge carrier photogeneration and recombination mechanisms in organic solar cells is still an ongoing effort. In donor:acceptor (bulk) heterojunction organic solar cells, charge photogeneration and recombination are inter‐related via the kinetics of charge transfer states—being singlet or triplet states. Although high‐charge‐photogeneration quantum yields are achieved in many donor:acceptor systems, only very few systems show significantly reduced bimolecular recombination relative to the rate of free carrier encounters, in low‐mobility systems. This is a serious limitation for the industrialization of organic solar cells, in particular when aiming at thick active layers. Herein, a meta‐analysis of the device performance of numerous bulk heterojunction organic solar cells is presented for which field‐dependent photogeneration, charge carrier mobility, and fill factor are determined. Herein, a “spin‐related factor” that is dependent on the ratio of back electron transfer of the triplet charge transfer (CT) states to the decay rate of the singlet CT states is introduced. It is shown that this factor links the recombination reduction factor to charge‐generation efficiency. As a consequence, it is only in the systems with very efficient charge generation and very fast CT dissociation that free carrier recombination is strongly suppressed, regardless of the spin‐related factor.…
Author details: | Safa ShoaeeORCiDGND, Ardalan ArminORCiD, Martin StolterfohtORCiDGND, Seyed Mehrdad HosseiniORCiDGND, Jona KurpiersORCiDGND, Dieter NeherORCiDGND |
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URN: | urn:nbn:de:kobv:517-opus4-437512 |
DOI: | https://doi.org/10.25932/publishup-43751 |
ISSN: | 1866-8372 |
Title of parent work (German): | Postprints der Universität Potsdam Mathematisch-Naturwissenschaftliche Reihe |
Publication series (Volume number): | Zweitveröffentlichungen der Universität Potsdam : Mathematisch-Naturwissenschaftliche Reihe (773) |
Publication type: | Postprint |
Language: | English |
Date of first publication: | 2019/11/22 |
Publication year: | 2019 |
Publishing institution: | Universität Potsdam |
Release date: | 2019/11/22 |
Tag: | charge generation; charge transfers; non-Langevin recombination; spin-related factors |
Issue: | 773 |
Number of pages: | 8 |
Source: | Solar RRL (2019) Art. 1900184 DOI: 10.1002/solr.201900184 |
Organizational units: | Mathematisch-Naturwissenschaftliche Fakultät |
DDC classification: | 6 Technik, Medizin, angewandte Wissenschaften / 60 Technik / 600 Technik, Technologie |
Peer review: | Referiert |
Publishing method: | Open Access |
Grantor: | DEAL Wiley |
License (German): | CC-BY - Namensnennung 4.0 International |