The presence of inherent imperfections at the perovskite-electron-transport layer (ETL) interface adversely affects the efficiency and stability of perovskite solar cells (PSCs). Here, 2-amino-1,3-propanediol (APDO) is preburied to stabilize the bottom side of the SnO2 ETL, eliminating inherent defects and passivating interface recombination. Meanwhile, the "anchoring effect" triggered by APDO at the grain growth interface can regulate the crystallization of perovskite crystals, which leads to perovskite films with homogeneous and fewer defects. Two methods are used to prebury the SnO2 ETL, which are marked as SnO2-APDO (doped) and SnO2/APDO (modified). Finally, the control device with MAPbI(3) achieved a champion power conversion efficiency (PCE) of 20.17%, while with SnO2/APDO and SnO2-APDO ETL the values are 21.08% and 21.93%. Under a relative humidity (RH) of 30-40%, after 500 h of aging, unpackaged PSCs with SnO2/APDO and SnO2-APDO ETL maintain the original PCE of 89% and 93%, which with SnO2 ETL only maintain a PCE of 79%. The PCE of flexible PSCs with SnO2-APDO ETL increased from 18.87% to 20.64%, and the optimized device still maintains 89% of initial PCE after 5000 bending cycles with a bend radius of 5 mm, indicating that the introduction of APDO is an effective strategy to achieve high photovoltaic performance.