Steric hindrance induced low exciton binding energy enables low-driving-force organic solar cells
Tianyu Hu , Xufan Zheng , Ting Wang , Aziz Saparbaev , Bowen Gao , Jingnan Wu , Jingyi Xiong , Ming Wan , Tingting Cong , Yuda Li , Ergang Wang , Xunchang Wang , Renqiang Yang
Aggregate ›› 2024, Vol. 5 ›› Issue (5) : e632
Steric hindrance induced low exciton binding energy enables low-driving-force organic solar cells
Exciton binding energy (Eb) has been regarded as a critical parameter in charge separation during photovoltaic conversion. Minimizing the Eb of the photovoltaic materials can facilitate the exciton dissociation in low-driving force organic solar cells (OSCs) and thus improve the power conversion efficiency (PCE); nevertheless, diminishing the Eb with deliberate design principles remains a significant challenge. Herein, bulky side chain as steric hindrance structure was inserted into Y-series acceptors to minimize the Eb by modulating the intra- and intermolecular interaction. Theoretical and experimental results indicate that steric hindrance-induced optimal intra- and intermolecular interaction can enhance molecular polarizability, promote electronic orbital overlap between molecules, and facilitate delocalized charge transfer pathways, thereby resulting in a low Eb. The conspicuously reduced Eb obtained in Y-ChC5 with pinpoint steric hindrance modulation can minimize the detrimental effects on exciton dissociation in low-driving-force OSCs, achieving a remarkable PCE of 19.1% with over 95% internal quantum efficiency. Our study provides a new molecular design rationale to reduce the Eb.
exciton binding energy / exciton dissociation / organic solar cells / steric hindrance
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2024 The Author(s). Aggregate published by SCUT, AIEI, and John Wiley & Sons Australia, Ltd.
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