Precrystallization of the Cs<sub>2</sub>PbI<sub>2</sub>Cl<sub>2</sub> Intermediate Phase for MA- and Br-Free Wide Bandgap Perovskite Solar Cells
Yijin Wei, Zhipeng Shao, Zhipeng Li, Caiyun Gao, Xiuhong Sun, Qiangqiang Zhao, Lianzheng Hao, Bingqian Zhang, Dachang Liu, Xianzhao Wang, Changcheng Cui, Qi Huang, Yaliang Han, Xiao Wang, Guanglei Cui, Shuping Pang
Abstract
A wide bandgap perovskite has broad application prospects in perovskite-based tandem solar cells. However, the I/Br mixed wide bandgap perovskite suffers from inevitable photoinduced halide segregation, while the pure iodine wide bandgap perovskite FA 1– x Cs x PbI 3 ( x > 0.3) typically has high defect densities due to its high annealing temperatures. To address these issues, we reported a Cs 2 PbI 2 Cl 2 intermediate method to lower the preparation temperature and prepare high-quality FA 0.5 Cs 0.5 PbI 3 perovskite films. The precrystallization of the Cs 2 PbI 2 Cl 2 intermediate phase demonstrated effective control over Cs-rich intermediate phases in the raw films, resulting in accelerated ion exchange, lowered activation energy of the solid reaction, and reduced defect density. Consequently, the champion device reaches a power conversion efficiency (PCE) of 22.67%, with only 3% degradation after 500 h of continuous operation. Importantly, the champion mini-module (active area of 14 cm 2 ) reached a PCE of 18.46% which is one of the highest perovskite solar modules based on wide bandgap perovskites.