Solvent Engineering Approach Toward Optimized Phase and Morphology of CsPbBr<sub>3</sub> Films for Efficient and Stable Planar Perovskite Solar Cells and Photodetectors
Kaiyuan Xu, Long Zhou, Xi Chen, Siyu Zhang, Xing Guo, Chunhui Shou, Zhenhua Lin, Jincheng Zhang, Jingjing Chang, Yue Hao
Abstract
All‐inorganic perovskite CsPbBr 3 has drawn a lot of interest as an active layer applied in photovoltaics due to its outstanding stability in ambient air. However, the procedure of preparing high‐quality CsPbBr 3 films still remains a serious challenge because of the tedious process and toxic solvent. Herein, a solvent engineering method that involves green solvent with mixed H 2 O/C 2 H 5 OH to dissolve CsBr is presented to produce all‐inorganic perovskite CsPbBr 3 films. CsPbBr 3 perovskite solar cells (PSCs) are fabricated based on planar n‐i‐p structure. Compared with CsBr H 2 O solution, the CsPbBr 3 films with optimized mixed solvent method exhibit larger grain size and improved crystallinity. As a result, the carbon‐electrode PSCs based on the mixed solvent method exhibit an increased efficiency of 9.70%. The best‐performing device retains 96.95% of the initial power conversion efficiency (PCE) after storing 1000 h under ambient air and 86.46% of the initial PCE after continuous illumination for 100 min. Moreover, the photodetector based on the same structure as the CsPbBr 3 device shows high responsivity and high detectivity. The result not only provides an easy and straightforward method to prepare the uniform and pinhole‐free CsPbBr 3 films, but also reduces the toxicity of the CsBr solution used to make the CsPbBr 3 PSCs.