Suppressing electron-phonon coupling in organic photovoltaics for high-efficiency power conversion

作者：Yuanyuan Jiang, Yixin Li, Feng Liu, Wenxuan Wang, Wenli Su, Wuyue Liu, Songjun Liu, Wenkai Zhang, Jianhui Hou, Shengjie Xu, Yuanping Yi, Xiaozhang Zhu · 发表于：Nature Communications · 年份：2023 · DOI：10.1038/s41467-023-40806-9 · 被引用次数：145 · 研究领域：Organic Electronics and Photovoltaics、Conducting polymers and applications、Perovskite Materials and Applications

Abstract The nonradiative energy loss (∆Enr) is a critical factor to limit the efficiency of organic solar cells. Generally, strong electron-phonon coupling induced by molecular motion generates fast nonradiative decay and causes high ∆Enr. How to restrict molecular motion and achieve a low ∆Enr is a sticking point. Herein, the free volume ratio (FVR) is proposed as an indicator to evaluate molecular motion, providing new molecular design rationale to suppress nonradiative decay. Theoretical and experimental results indicate proper proliferation of alkyl side-chain can decrease FVR and restrict molecular motion, leading to reduced electron-phonon coupling while maintaining ideal nanomorphology. The reduced FVR and favorable morphology are simultaneously obtained in AQx-6 with pinpoint alkyl chain proliferation, achieving a high PCE of 18.6% with optimized VOC, JSC and FF. Our study discovered aggregation-state regulation is of great importance to the reduction of electron-phonon coupling, which paves the way to high-efficiency OSCs.