Radical Molecular Network‐Buffer Minimizes Photovoltage Loss in FAPbI₃ Perovskite Solar Cells
Mubai Li, Yang Jiang, Shaoyu Chen, Zhangsheng Shi, Qingyun He, Junbo Wang, Mengyang Wu, Chongyu Zhong, Xiangru Zhao, Pinghui Yang, Zhizhong Lin, Jingya Lai, Renzhi Li, Jingjin Dong, Aifei Wang, Mathias Uller Rothmann, Yi‐Bing Cheng, Wei Huang, Tianshi Qin, Wei Li, Fangfang Wang
Abstract
Abstract Formamidinium lead iodide (FAPbI₃) perovskite solar cells (PSCs) hold immense potential for high‐efficiency photovoltaics, but maximizing their open‐circuit voltage ( V OC ) remains challenging. Targeting the inherently stable {111} c ‐dominant facets is a promising approach for enhancing stability, but their formation typically suffers from high defect densities and disordered growth. This study introduces a novel approach using an in situ polymerizable radical molecule, ATEMPO, as an additive to address these issues. ATEMPO preferentially interacts with the {111} c perovskite facets, guiding their growth and forming a “radical molecular network‐buffer” upon polymerization. The network effectively mitigates lattice strain, suppresses defect formation, enhances charge transport via redox‐mediated hopping, and provides a hydrophobic barrier, significantly improving moisture resistance. This strategy yields high‐quality, {111} c ‐oriented FAPbI₃ films, leading to a champion PCE of 25.28% with a remarkably high V OC of 1.203 V, corresponding to an energy loss ( E loss ) of only 0.297 eV, among the highest V OC reported for FAPbI₃‐based PSCs. Furthermore, a mini‐module fabricate with an active area of 12.5 cm 2 achieve a high PCE of 21.39%. the work paves the way for developing high‐performance, stable PSCs with minimized photovoltage loss. Furthermore, it offers a promising strategy to enhance device longevity and address environmental concerns.