Effects of methylamine doping on the stability of triple cation (FA(0.95−x)MA(x)Cs(0.05))PbI(3) single crystal perovskites

Despite being promising photovoltaic materials, widespread use of organic–inorganic halide perovskite materials is still hindered by their undesirable stability. To cope with this challenge, methylamine (MA) is doped into triple cation perovskite single crystals of (FA(0.95−x)MA(x)Cs(0.05))PbI(3), and cesium-containing triple cation perovskite single crystals with five different MA molar ratios (x = 0, 0.05, 0.10, 0.15, and 0.20) are synthesized and characterized. Among them, (FA(0.8)MA(0.15)Cs(0.05))PbI(3) shows high stability against water-oxygen and light for 60 days, and the thermal decomposition temperature of (FA(0.8)MA(0.15)Cs(0.05))PbI(3) reaches as high as 305 °C. Besides, the carrier lifetime of (FA(0.8)MA(0.15)Cs(0.05))PbI(3) is up to 5.957 μs, which remains as 5.646 μs (95%) after 60 days of light illumination. This work studies the stability of perovskite single crystals based on (FA(0.95−x)MA(x)Cs(0.05))PbI(3) compositions and provides a reference for the discovery of novel perovskite photovoltaic devices with high efficiency and long-term stability.