Structurally Reconstructed CsPbI2Br Perovskite for Highly Stable and Square‐Centimeter All‐Inorganic Perovskite Solar Cells

• Published in: Advanced energy materials Vol. 9; no. 7
• Main Authors: Liu, Chong, Li, Wenzhe, Li, Huanyong, Wang, Huamin, Zhang, Cuiling, Yang, Yingguo, Gao, Xingyu, Xue, Qifan, Yip, Hin‐Lap, Fan, Jiandong, Schropp, Ruud E. I., Mai, Yaohua
• Format: Journal Article
• Language: English
• Published: Weinheim Wiley Subscription Services, Inc 14.02.2019
• Subjects: all‐inorganic perovskite solar cells; Cesium; Crystal structure; Energy conversion efficiency; Iodine; Perovskites; phase stability; Photovoltaic cells; Solar cells; structural reconstruction; Thermal radiation; Thermal stability; Thin films
• ISSN: 1614-6832; 1614-6840
• DOI: 10.1002/aenm.201803572

Although all‐inorganic perovskite solar cells (PSCs) demonstrate high thermal stability, cesium‐lead halide perovskites with high iodine content suffer from poor stability of the black phase (α‐phase). In this study, it is demonstrated that incorporating InCl3 into the host perovskite lattice helps to inhibit the formation of yellow phase (δ‐phase) perovskite and thereby enhances the long‐term ambient stability. The enhanced stability is achieved by a strategy for the structural reconstruction of CsPbI2Br perovskite by means of In3+ and Cl− codoping, which gives rise to a significant improvement in the overall spatial symmetry with a closely packed atom arrangement due to the crystal structure transformation from orthorhombic (Pnma) to cubic (Pm‐3m). In addition, a novel thermal radiation heating method that further improves the uniformity of the perovskite thin films is presented. This approach enables the construction of all‐inorganic InCl3:CsPbI2Br PSCs with a champion power conversion efficiency of 13.74% for a small‐area device (0.09 cm2) and 11.4% for a large‐area device (1.00 cm2). Incorporation of indium(III) chloride is directly shown to induce the structural reconstruction of CsPbI2Br perovskite at the microscopic level, which allows the stabilization of the α‐phase perovskite by means of increasing the structure tolerance factor and decreasing the grain size. Consequently, the square‐centimeter all‐inorganic InCl3:CsPbI2Br perovskite solar cells yield a power conversion efficiency of 11.4% with high stability.