A unified description of non-radiative voltage losses in organic solar cells

Xian Kai Chen, Deping Qian, Yuming Wang, Thomas Kirchartz, Wolfgang Tress, Huifeng Yao, Jun Yuan, Markus Hülsbeck, Maojie Zhang, Yingping Zou, Yanming Sun, Yongfang Li, Jianhui Hou, Olle Inganäs, Veaceslav Coropceanu, Jean Luc Bredas, Feng Gao

Research output: Contribution to journalArticlepeer-review

49 Scopus citations

Abstract

Recent advances in organic solar cells based on non-fullerene acceptors (NFAs) come with reduced non-radiative voltage losses (ΔVnr). Here we show that, in contrast to the energy-gap-law dependence observed in conventional donor:fullerene blends, the ΔVnr values in state-of-the-art donor:NFA organic solar cells show no correlation with the energies of charge-transfer electronic states at donor:acceptor interfaces. By combining temperature-dependent electroluminescence experiments and dynamic vibronic simulations, we provide a unified description of ΔVnr for both fullerene- and NFA-based devices. We highlight the critical role that the thermal population of local exciton states plays in low-ΔVnr systems. An important finding is that the photoluminescence yield of the pristine materials defines the lower limit of ΔVnr. We also demonstrate that the reduction in ΔVnr (for example, <0.2 V) can be obtained without sacrificing charge generation efficiency. Our work suggests designing donor and acceptor materials with high luminescence efficiency and complementary optical absorption bands extending into the near-infrared region.

Original languageEnglish (US)
Pages (from-to)799-806
Number of pages8
JournalNature Energy
Volume6
Issue number8
DOIs
StatePublished - Aug 2021

ASJC Scopus subject areas

  • Electronic, Optical and Magnetic Materials
  • Renewable Energy, Sustainability and the Environment
  • Fuel Technology
  • Energy Engineering and Power Technology

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