<i>p</i>‐Type Charge Transfer Doping of Graphene Oxide with (NiCo)_1−<i>y</i>Fe_<i>y</i>O_<i>x</i> for Air‐Stable, All‐Inorganic CsPbIBr₂ Perovskite Solar Cells

The precise regulation of interfacial charge distribution highly determines the power conversion efficiency of perovskite solar cells (PSCs). Herein, inorganic (NiCo)_1-y Fe_y O_x nanoparticle decorated graphene oxide (GO) is successfully demonstrated as a hole booster for all-inorganic CsPbIBr₂ PSC free of precious metal electrode. Arising from the spontaneous electron transfer induced p-type doping of GO from edged oxygen-containing functional groups to (NiCo)_1-y Fe_y O_x , the best all-inorganic CsPbIBr₂ PSC achieves an efficiency of 10.95 % under one standard sun owing to the eliminated paradox between charge extraction and charge localization in GO surface. Furthermore, the champion device exhibits an excellent long-term stability at 10 % relative humidity without encapsulation over 70 days because of the suppressed ions migration.