Bright Organic Semiconductors for Highly Efficient Organic Solar Cells

Professor Feng Gao
Professor and Head of the Optoelectronics Unit, Linköping University, Sweden

Description

WILLIAM MONG DISTINGUISHED LECTURES: RPG SHARING SERIES:

The power conversion efficiencies (PCEs) of organic solar cells (OSCs) have now reached high values approaching 20%. These recent advances in OSCs based on non-fullerene acceptors (NFAs) come with reduced non-radiative voltage losses. In contrast to the energy-gap-law dependence observed in conventional donor:fullerene blends, the non-radiative voltage losses 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 dynamic vibronic simulations with temperature-dependent electroluminescence experiments, we provide a unified description of non-radiative voltage losses for both fullerene- and NFA-based devices. We highlight that the photoluminescence yield of the pristine materials defines the lower limit of non-radiative voltage losses. We further investigate the dominant non-radiative recombination processes in state-of-the-art NFAs, providing rational materials design rules for enhancing the PCEs of OSCs by increasing the photoluminescence yield of NFAs.

About the Speaker

Professor Feng Gao is a full professor and head of the Optoelectronics Unit at Linköping University in Sweden since 2020. He has been appointed as a Wallenberg Scholar since 2024. His group focuses on emerging semiconductors for next-generation optoelectronic devices. He obtained his Ph.D. degree (2011) from the University of Cambridge, M.S. (2007) and B.S. (2004) degrees from Nanjing University. He received from the European Research Council (ERC) an ERC Consolidator Grant (2021) and an ERC Starting Grant (2016). He became a Swedish Foundation for Strategic Research (SSF) Future Research Leader in 2019 and a Wallenberg Academy Fellow in 2017. He received the Tage Erlander Prize in Physics (2020) and the Göran Gustafsson Prize in Physics (2025), both awarded by the Royal Swedish Academy of Sciences.

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