Electron diffusion at Sn perovskite/fullerene derivative interfaces and its influence on open-circuit voltage

Abstract Tin-based perovskite solar cells (PSCs) are the most promising alternatives to toxic lead-based ones. However, the loss in open-circuit voltage (V OC) remains an important issue. Improvement of V OC has been achieved by using a fullerene derivative, indene-C60 bisadduct (ICBA), as the elect...

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Main Authors: Atushi Sato, Seira Yamaguchi, Akio Hasegawa, Yukihiro Shimoi, Tomoya Nakamura, Atsushi Wakamiya, Kazuhiro Marumoto
Format: Article
Language:English
Published: Nature Portfolio 2025-05-01
Series:npj Flexible Electronics
Online Access:https://doi.org/10.1038/s41528-025-00424-5
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Summary:Abstract Tin-based perovskite solar cells (PSCs) are the most promising alternatives to toxic lead-based ones. However, the loss in open-circuit voltage (V OC) remains an important issue. Improvement of V OC has been achieved by using a fullerene derivative, indene-C60 bisadduct (ICBA), as the electron transporting layer (ETL). For further V OC improvement, the V OC improvement mechanisms must be clarified. Herein, we show, at a molecular level, V OC improvement mechanisms by an ICBA ETL in tin-based PSCs. Electron spin resonance spectroscopy reveals that electron diffusion from perovskite to ETL occurs at perovskite/ETL interfaces, producing unfavorable upward band-bending of perovskite. Employing ICBA with a shallower LUMO level suppresses the upward band-bending as well as reduces the energy offset with the conduction band minimum of perovskite. Suppressing this unfavorable upward band-bending reduces interface recombination at perovskite/ETL interfaces and contributes to V OC improvement. These insights support efficient optimization of the charge-transporting layer for additional improvement of V OC.
ISSN:2397-4621