Phase Stability Improvement of a γ-CsPbI<sub>3</sub> Perovskite Solar Cell Utilizing a Barium Bis(trifluoromethanesulfonimide) Solution
Chanyong Lee, Kyungjin Chae, Yohan Ko, Changhyun Lee, Taemin Kim, Seaeun Park, Moo Young Jung, Jinhyoung Kim, Yong Ju Yun, Minoh Lee, Yongseok Jun
Abstract
The cesium lead iodide (CsPbI 3 ) perovskite solar cell possesses a wide band gap ranging from 1.65 to 1.75 eV, which is suitable for integration into a tandem structure along with a low-band-gap silicon solar cell. Moreover, CsPbI 3 has received considerable attention as a potential solution for the prevalent issues of low thermal stability of organic–inorganic perovskite solar cells and phase segregation encountered in conventional mixed halide wide-band-gap perovskite solar cells. Through the implementation of volatile additives, CsPbI 3 has demonstrated substantial advancements in efficiency, process temperature, and stability. This study introduces a novel approach for barium (Ba)-doping by spraying an antisolvent containing barium bis(trifluoromethanesulfonimide) during the spin-coating process. By incorporating Ba 2+ through this spraying technique, the formation of the delta phase in CsPbI 3 is significantly suppressed; thereby, a power conversion efficiency of 18.56% is achieved, and a remarkable 93% of the initial efficiency is maintained after 600 h.