The application of Al2TiO5 at the TiO2/perovskite interface to decrease carrier losses in solar cells

Abstract

Herein we describe the mechanism of crystallization of Al³⁺ with amorphous TiO₂ on a TiO₂ film, and found that the resultant Al₂TiO₅ was able to improve the average efficiency of planar perovskite solar cells (PSCs) from 15.4 to 17.2%. The electron lifetime in these Al-PSCs was about 3 times longer than that in unmodified PSCs. The O 1s X-ray photoelectron spectrum of the TiO₂/CH₃NH₃PbI₃ interface indicated that the oxygen vacancy or defect peak decreased by more than 31% on modifying the interface with Al₂TiO₅. The stability of the PSCs was improved substantially: Al-PSCs had still 88% of their initial value after 1440 hours, while the efficiency of the reference PSCs decreased to 68% of their initial value.