Self‐Assembled Charge Bridge Path at the Sn‐Pb Perovskite/C <sub>60</sub> Interface for High‐Efficiency All‐Perovskite Tandem Solar Cells
Yuting Shu, Jiankai Xie, Jiupeng Cao, Wenjian Yan, Xiaonan Jin, Lujia Han, Jibiao Duan, Mingjun Hu, Shunan Sui, Huihui Zhang, Fangfang Wang, Jingjin Dong, Aifei Wang, Wei Huang, Tianshi Qin
Abstract
Abstract Narrow bandgap mixed tin‐lead perovskite solar cells (PSCs) have garnered substantial research interest owing to their remarkable optoelectronic properties. However, non‐radiative recombination and carrier transport losses at the interface between the perovskite layer and the charge transport layer (C 60 ) significantly reduce the overall efficiency of mixed tin‐lead PSCs. To address this challenge, 9‐Fluorenylmethyl carbazate (9FC) is incorporated at the interface between perovskite and C 60 . The hydrazide group present in 9FC effectively mitigates the oxidation of Sn 2+ . Furthermore, 9FC can engage in chemical bonding with the perovskite, while the outward‐facing aromatic rings create effective π – π interactions with C 60 , thereby promoting enhanced interfacial charge transfer. The highest‐performing mixed tin‐lead PSCs achieve a power conversion efficiency (PCE) of 23.97%, accompanied by an impressive open‐circuit voltage of 0.91 V. Additionally, these tin‐lead PSCs facilitate the development of highly efficient two‐terminal and four‐terminal all‐perovskite tandem solar cells, which demonstrate efficiencies of 27.01% and 28.07%, respectively.