▎ 摘　　要

For practical use of perovskite solar cells (PSCs) the instability issues of devices, attributed to degradation of perovskite molecules by moisture, ions migration, and thermal- and light-instability, have to be solved. Herein, highly efficient and stable PSCs based on perovskite/Ag-reduced graphene oxide (Ag-rGO) and mesoporous Al2O3/graphene (mp-AG) composites are reported. The mp-AG composite is conductive with one-order of magnitude higher mobility than mp-TiO2 and used for electron transport layer (ETL). Compared to the mp-TiO2 ETL based cells, the champion device based on perovskite/Ag-rGO and SrTiO3/mp-AG composites shows overall a best performance (i.e., V-OC = 1.057 V, J(SC) = 25.75 mA cm(-2), fill factor (FF) = 75.63%, and power conversion efficiency (PCE) = 20.58%). More importantly, the champion device without encapsulation exhibits not only remarkable thermal- and photostability but also long-term stability, retaining 97-99% of the initial values of photovoltaic parameters and sustaining approximate to 93% of initial PCE over 300 d under ambient conditions.