In recent years, perovskite solar cells have attracted many researchers’ interest because of the rapid increment of the efficiency of perovskite solar cells. Titanium dioxide is used widely as the electron transportation layer (ETL), but it needs high temperature process. Owing to the preparation at low temperature, Zinc oxide is regarded as the promising materials for the ETL of the flexible perovskite solar cells. ZnO nanorods is grown to improve the efficiency of charges transportation. As shown in Fig.1 (a), a dense of ZnO nanorods arrays have been prepared on conductive glass (SnO₂: F) (FTO) substrate by hydrothermal growth. The compact seed ZnO layer between the ZnO nanorods and FTO is prepared by the spin-coating method. The defects on the nanorods may induce the degeneration of the performance of ZnO based perovskite solar cells. Ultra-thin Al₂O₃ film is deposited by atomic layer deposition (ALD) on the ZnO nanorods with 5 cycles to passivate the defects. The perovskite layer is afterwards spin-coated on passiviated ZnO nanorods, and holes transportation material (HTM) is prepared on the top of perovskite subsequently as shown in Fig.1 (b). ZnO based perovskite solar cell is fabricated after the evaporation of gold electrode on HTM layer. Because the thickness of Al₂O₃ coating layer is less than 1nm, the photogenerated electrons can easily tunnel to the ZnO layer and realize the separation of charges. The average photoelectric conversion efficiency of Al₂O₃ coated perovskite solar cells based on ZnO nanorods has been improved by10% .