Light stability tests of methylammonium and formamidinium Pb-halide perovskites for solar cell applications

We have prepared perovskite [CH3NH3PbI3 (MALI), CH3NH3PbBr3 (MALB), NH2CH=NH2PbI3 (FALI), and NH2CH=NH2PbBr3 (FALB)] thin films by a one-step process on glass/TiO2 and glass/Al2O3 substrates and studied the stability of the perovskite under UV/visible light radiation up to 24 h at 1.5AM in air. After irradiation, the films were characterized by UV-vis absorption and X-ray diffraction measurements. In addition, photovoltaic performance characteristics in air were studied using different perovskites before (0 h) and after 24 h irradiation. The results revealed that Al2O3 protected the perovskite crystal from degradation. However, the perovskites were unstable except for NH2CH=NH2PbI3 un der the same conditions using a TiO2 scaffold layer. (C) 2015 The Japan Society of Applied Physics