Abstract
Hybrid organic/inorganic perovskites as light absorption layer have received considerable attention because of their preeminent photovoltaic performance. Presently, gaining high power conversion efficiency (PCE) and longterm stability of perovskite solar cells (PSCs) is very crucial to achieve their practical application. Here, NH4I was introduced to fabricate the mixed dimensional (MD) perovskite films at different annealing temperatures. The addition of NH4I could improve the preferential crystal orientation within the polycrystalline, favor the formation of MD perovskite, and suppress the existence of yellow PbI2 phase. The results indicate that MD perovskite films have a smoother surface, preferentially oriented perovskite crystal, and better optical properties at the same annealing temperature, compared with formamidinium (FA) perovskite. The MD perovskite device displays excellent photovoltaic performance possessing a high PCE of 18.93% at 100 degrees C. More importantly, the 1200 h humidity and 200 h heat stability tests reveal that the MD perovskite devices at optimized annealing temperature show great stability against moisture and heat. The findings are crucial to perovskite photovoltaics on improving the PCE and the long-term stability in industrialization and other applications.