Nanoporous p-type NiOx electrode for p-i-n inverted perovskite solar cell toward air stability

Designing air-stable perovskite solar cells (PSCs) is a recent trend in low-cost photovoltaic technology. Metal oxide-based electron transporting layers (ETLs) and hole transporting layers (HTLs) have attracted tremendous attention in PSCs, because of their excellent air stability, high electron mobility, and optical transparency. Herein, we report a co-precipitation method for the synthesis of p-type nanoporous nickel oxide (np-NiOx) thin films as the HTL for inverted (p-i-n) PSCs. The best-performing p-i-n PSC having np-NiOx HTL, (FAPbI₃)_0.85(MAPbBr₃)_0.15 (herein FAPbI₃ stands for formamidinium lead iodide and MAPbBr₃ stands for methylammonium lead bromide) perovskite and phenyl-C₆₁-butyric acid methyl ester (PCBM)/ZnO ETL exhibited a 19.10% (±1%) power conversion efficiency (PCE) with a current density (J_SC) of 22.76?mA?cm^?2, open circuit voltage (V_OC) of 1.076?V and fill factor (FF) of 0.78 under 1?sun (100?mW?cm^?2). Interestingly, the developed p-i-n PSCs based on p-type NiOx and n-type ZnO could retain >80% efficiency after 160?days, which is much higher than conventional PEDOT:PSS HTL-based PSCs. Our findings provide air-stable perovskite solar cells with high efficiency.