Managing Phase Purities and Crystal Orientation for High‐Performance and Photostable Cesium Lead Halide Perovskite Solar Cells
Qiong Wang, Joel A. Smith, Dieter Skroblin, Julian A. Steele, Christian M. Wolff, Pietro Caprioglio, Martin Stolterfoht, Hans Köbler, Meng Li, Silver‐Hamill Turren‐Cruz, Christian Gollwitzer, Dieter Neher, Antonio Abate
Abstract
Inorganic perovskites with cesium (Cs + ) as the cation have great potential as photovoltaic materials if their phase purity and stability can be addressed. Herein, a series of inorganic perovskites is studied, and it is found that the power conversion efficiency of solar cells with compositions CsPbI 1.8 Br 1.2 , CsPbI 2.0 Br 1.0 , and CsPbI 2.2 Br 0.8 exhibits a high dependence on the initial annealing step that is found to significantly affect the crystallization and texture behavior of the final perovskite film. At its optimized annealing temperature, CsPbI 1.8 Br 1.2 exhibits a pure orthorhombic phase and only one crystal orientation of the (110) plane. Consequently, this allows for the best efficiency of up to 14.6% and the longest operational lifetime, T S80 , of ≈300 h, averaged of over six solar cells, during the maximum power point tracking measurement under continuous light illumination and nitrogen atmosphere. This work provides essential progress on the enhancement of photovoltaic performance and stability of CsPbI 3 − x Br x perovskite solar cells.