A New Approach to Study Stability in a Lead‐Free Perovskite Cs 4 CuSb 2 Cl 12 ‐Based Solar Cell

We have simulated a solar cell of lead‐free inorganic perovskite Cs 4 CuSb 2 Cl 12 of the optimized structure, FTO/WS 2 /Cs 4 CuSb 2 Cl 12 /P 3 HT/Co, which is expected to be more stable compared with solar cells containing halide perovskite. First, a few different anode, electron transport layer, and hole transport layer materials are tried, and then the above best combination is found to give the highest power conversion efficiency. Following that, the thickness of the active layer, the concentration of the defect density in the interfaces of WS 2 /Cs 4 CuSb 2 Cl 12 and Cs 4 CuSb 2 Cl 12 /P 3 HT, and in the active layer are optimized. The optimal structure of FTO/WS 2 /Cs 4 CuSb 2 Cl 12 /P 3 HT/Co thus determined reveals J SC = 23.64 mA/cm 2 , V OC = 1.44 V, FF = 84.87% and PCE = 28.97%. We have also assessed the stability of this PSC by reducing the number of interfaces, which are apparently responsible for degradation. The above PSC without both HTL and ETL reveals a lower PCE of 18.9% but may be considered more stable, and the PSC without the ETL gives a PCE of 29.3% because this structure supports better charge carrier transport. As the active layer of this PSC is inorganic, it is expected to be more stable.