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

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 InCl 3 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 CsPbI 2 Br perovskite by means of In 3+ 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 InCl 3 :CsPbI 2 Br PSCs with a champion power conversion efficiency of 13.74% for a small-area device (0.09 cm 2 ) and 11.4% for a large-area device (1.00 cm 2 ).