Electron transport layer assisted by nickel chloride hexahydrate for open-circuit voltage improvement in MAPbI₃...

SnO₂ is a promising electron transport layer (ETL) material with important applications in planar perovskite solar cells (PSCs). However, electron-hole recombination and charge extraction between SnO₂ and the perovskite layer necessitates further exploration. Nickel chloride hexahydrate (NiCl₂·6H₂O) was introduced into the SnO₂ ETL, which significantly increased the power conversion efficiency (PCE) from 15.49 to 17.36% and the open-circuit voltage (V _OC) from 1.078 to 1.104 V. The improved PCE and V _OC were attributed to the reduced defect states and increased energy level of the conduction band minimum. This work provides new insights into optimizing the V _OC and PCE of PSCs.