Academic Journal
The role of exciton lifetime for charge generation in organic solar cells at negligible energy-level offsets
| Title: | The role of exciton lifetime for charge generation in organic solar cells at negligible energy-level offsets |
|---|---|
| Authors: | Jonas Wortmann, Larry Lüer, Thomas Heumüller, Karen Forberich, Andres Osvet, Andrej Classen, Iain McCulloch, Christoph J. Brabec, Christos L. Chochos, Vasilis G. Gregoriou |
| Contributors: | Copyright © 2020 Springer Nature Limited, Chemical Science Program, KAUST Solar Center (KSC), Physical Science and Engineering (PSE) Division, Institute of Materials for Electronics and Energy Technology (i-MEET), Friedrich-Alexander University Erlangen-Nürnberg, Erlangen, Germany, Advent Technologies SA, Platani, Greece, Institute of Chemical Biology, National Hellenic Research Foundation (NHRF), Athens, Greece, National Hellenic Research Foundation (NHRF), Athens, Greece, Department of Chemistry, Chemistry Research Laboratory, University of Oxford, Oxford, UK, Helmholtz-Institute Erlangen-Nürnberg (HI ERN), Erlangen, Germany, Bavarian Center for Applied Energy Research (ZAE Bayern), Erlangen, Germany |
| Source: | Nature energy 5(9), 711-719 (2020). doi:10.1038/s41560-020-00684-7 |
| Publisher Information: | Springer Science and Business Media LLC, 2020. |
| Publication Year: | 2020 |
| Subject Terms: | Photovoltaics, Τεχνολογικές καινοτομίες. Αυτοματοποίηση, Technological innovations. Automation, Χημική τεχνολογία, Photonic devices, Physics, Electronic devices, Φυσική, 01 natural sciences, 7. Clean energy, Chemical technolgy, 0104 chemical sciences |
| Description: | Organic solar cells utilize an energy-level offset to generate free charge carriers. Although a very small energy-level offset increases the open-circuit voltage, it remains unclear how exactly charge generation is affected. Here we investigate organic solar cell blends with highest occupied molecular orbital energy-level offsets (∆EHOMO) between the donor and acceptor that range from 0 to 300 meV. We demonstrate that exciton quenching at a negligible ∆EHOMO takes place on timescales that approach the exciton lifetime of the pristine materials, which drastically limits the external quantum efficiency. We quantitatively describe this finding via the Boltzmann stationary-state equilibrium between charge-transfer states and excitons and further reveal a long exciton lifetime to be decisive in maintaining an efficient charge generation at a negligible ∆EHOMO. Moreover, the Boltzmann equilibrium quantitatively describes the major reduction in non-radiative voltage losses at a very small ∆EHOMO. Ultimately, highly luminescent near-infrared emitters with very long exciton lifetimes are suggested to enable highly efficient organic solar cells. Donor–acceptor systems with low energy-level offset enable high power efficiency in organic solar cells yet it is unclear what drives charge generation. Classen et al. show that long exciton lifetimes enable efficient exciton splitting and thus generation of free charges while also suppressing voltage losses. |
| Document Type: | Article |
| Language: | English |
| ISSN: | 2058-7546 |
| DOI: | 10.1038/s41560-020-00684-7 |
| Access URL: | https://ui.adsabs.harvard.edu/abs/2020NatEn...5..711C/abstract https://www.scilit.net/article/081748705354da2df0c6d3ee9cb41c9d https://repository.kaust.edu.sa/handle/10754/664985 https://www.nature.com/articles/s41560-020-00684-7.pdf https://www.nature.com/articles/s41560-020-00684-7 https://jglobal.jst.go.jp/detail?JGLOBAL_ID=202002290447010479 https://hdl.handle.net/10442/17836 https://doi.org/10.1038/s41560-020-00684-7 https://juser.fz-juelich.de/record/890081 |
| Rights: | Springer Nature TDM URL: https://creativecommons.org/licenses/by-nc-nd/4.0/deed.el |
| Accession Number: | edsair.doi.dedup.....ba2d1f0c4f29b4f51a7062458a960f85 |
| Database: | OpenAIRE |
| ISSN: | 20587546 |
|---|---|
| DOI: | 10.1038/s41560-020-00684-7 |