Effect of bromide doping on the phase stability and shelf life of the triple cation mixed halide perovskite single-crystals

摘要

The spontaneous phase transition occurs in the Formamidinium lead iodide (FAPbI3) perovskite from photoactive black alpha-FAPbI3 to photo-inactive yellow 8- FAPbI3 poses a severe challenge to the long-term stability of this otherwise highly attractive photoactive material. The low-energy rotation of the formamidinium (FA) cation is expected to cause the phase instability of black alpha-FAPbI3 phase perovskite. When bromine is incorporated into the perovskite octahedron, the fraction of actively rotating FA molecules get reduced, resulting in the black phase stabilization. In this context, it has been reported here a method to grow single crystals of FA0.9MA0.05Cs0.05PbI3xBrx (x = 0, 0.3, 0.6 and 0.9) without yellow 8- FAPbI3 phase formation using bromine doping into the precursor solution. Further research into the effect of bromine content on the long-term stability of grown single crystals revealed that keeping the bromine content at 10 M percentage can extend the lifetime of the multi-cation perovskite single crystals over a month.