Abstract
Thermal stability of perovskite solar cells is crucial for their practical use. In this report, we show good 74% stability retention after a thermal stress test at 85 degrees C for 350 h) with high efficiency (>18%) using Rb modified perovskite absorber layers. It is posited that the mechanism of the thermal stability improvement is due to the formation of RbPbl(3) which suppresses Pbl(2) growth. This facile way for improving thermal stability is promising for realizing solar cells with high efficiency and stability.