Low‐Dimensional Dion–Jacobson‐Phase Lead‐Free Perovskites for High‐Performance Photovoltaics with Improved Stability
Pengwei Li, Xiaolong Liu, Yiqiang Zhang, Chao Liang, Gangshu Chen, Fengyu Li, Meng Su, Guichuan Xing, Xutang Tao, Lei Wu
Abstract
Abstract 1,4‐butanediamine (BEA) is incorporated into FASnI 3 (FA=formamidinium) to develop a series of lead‐free low‐dimensional Dion–Jacobson‐phase perovskites, (BEA)FA n −1 Sn n I 3 n +1 . The broadness of the (BEA)FA 2 Sn 3 I 10 band gap appears to be influenced by the structural distortion owing to high symmetry. The introduction of BEA ligand stabilizes the low‐dimensional perovskite structure (formation energy ca. 10 6 j mol −1 ), which inhibits the oxidation of Sn 2+ . The compact (BEA)FA 2 Sn 3 I 10 dominated film enables a weakened carrier localization mechanism with a charge transfer time of only 0.36 ps among the quantum wells, resulting in a carrier diffusion length over 450 nm for electrons and 340 nm for holes, respectively. Solar cell fabrication with (BEA)FA 2 Sn 3 I 10 delivers a power conversion efficiency (PCE) of 6.43 % with negligible hysteresis. The devices can retain over 90 % of their initial PCE after 1000 h without encapsulation under N 2 environment.