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.