Accelerated Sequential Deposition Reaction via Crystal Orientation Engineering for <scp>Low‐Temperature</scp>, <scp>High‐Efficiency Carbon‐Electrode CsPbBr₃</scp> Solar Cells

Abstract

Low‐temperature, ambient processing of high‐quality CsPbBr 3 films is demanded for scalable production of efficient, low‐cost carbon‐electrode perovskite solar cells (PSCs). Herein, we demonstrate a crystal orientation engineering strategy of PbBr 2 precursor film to accelerate its reaction with CsBr precursor during two‐step sequential deposition of CsPbBr 3 films. Such a novel strategy is proceeded by adding CsBr species into PbBr 2 precursor, which can tailor the preferred crystal orientation of PbBr 2 film from [020] into [031], with CsBr additive staying in the film as CsPb 2 Br 5 phase. Theoretical calculations show that the reaction energy barrier of (031) planes of PbBr 2 with CsBr is lower about 2.28 eV than that of (020) planes. Therefore, CsPbBr 3 films with full coverage, high purity, high crystallinity, micro‐sized grains can be obtained at a low temperature of 150 °C. Carbon‐electrode PSCs with these desired CsPbBr 3 films yield the record‐high efficiency of 10.27% coupled with excellent operation stability. Meanwhile, the 1 cm 2 area one with the superior efficiency of 8.00% as well as the flexible one with the champion efficiency of 8.27% and excellent mechanical bending characteristics are also achieved.