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

Abstract

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.