Study on the stability of CH3NH3PbI3 films and the effect of post-modification by aluminum oxide in all-solid-state hybrid solar cells

Degradation of perovskite has been a big problem in all-solid-state perovskite solar cells, although many researchers mainly focus on the high efficiency of these solar cells. This paper studies the stability of CH3NH3PbI3 films and finds that CH3NH3PbI3 is sensitive to moisture. The degradation reaction is proposed according to UV-Vis spectra and XRD results. In order to improve the degradation of CH3NH3PbI3, we introduce aluminum oxide as a post-modification material into all-solid-state perovskite solar cells for the first time. UV-Vis spectra show that Al2O3 modification could maintain the absorption of CH3NH3PbI3 after degradation. XRD results reveal that Al2O3 could protect perovskite from degradation. Moreover, the device post-modified by Al2O3 has shown more brilliant stability than that without modification when exposed to moisture. EIS results and dark current illustrate that the modification increased interface resistance in the dark, indicating the restrained electron recombination process.