Carrier Decay Properties of Mixed Cation Formamidinium–Methylammonium Lead Iodide Perovskite [HC(NH2)2]1–x[CH3NH3]xPbI3 Nanorods

Organic–inorganic lead iodide perovskites are efficient materials for photovoltaics and light-emitting diodes. We report carrier decay dynamics of nanorods of mixed cation formamidinium and methylammonium lead iodide perovskites [HC­(NH2)2]1–x[CH3NH3]xPbI3 (FA1–xMAxPbI3) synthesized through a simple solution method. The structure and FA/MA composition ratio of the single-crystal FA1–xMAxPbI3 nanorods are fully characterized, which shows that the mixed cation FA1–xMAxPbI3 nanorods are stabilized in the perovskite structure. The photoluminescence (PL) emission from FA1–xMAxPbI3 nanorods continuously shifts from 821 to 782 nm as the MA ratio (x) increases from 0 to 1 and is shown to be inhomogeneously broadened. Time-resolved PL from individual FA1–xMAxPbI3 nanorods demonstrates that lifetimes of mixed cation FA1–xMAxPbI3 nanorods are longer than those of the pure FAPbI3 or MAPbI3 nanorods, and the FA0.4MA0.6PbI3 displays the longest average PL lifetime of about 2 μs. These results suggest that mixed cation FA1–xMAxPbI3 perovskites are promising for high-efficiency photovoltaics and other optoelectronic applications.