Re-cyclic photophysics in perovskite Cs4PbBr6

Abstract

Most photophysical studies in the halide perovskite have focused on the characteristics of the surface. However, the photons generated at the surface would be absorbed by the same material (re-absorption), and the photophysics of re-absorbed photons are rarely studied. Herein, we present our recent observation of the re-emission (photoluminescence after re-absorption, I-R) in Cs4PbBr6, which is temporally slower than the surface-emission (I-S). We performed a characterization of Cs4PbBr6, a power dependence experiment, and a lifetime measurement to reveal the emitting properties of Cs4PbBr6. However, we characterized the first re-emission (re-emission after first re-absorption, I-FR) of Cs4PbBr6. The analysis of I-FR revealed that the energy intervals between I-S and I-FR and between I-FR and final re-emission (I-R) are close to integer multiples. Therefore, we suggested that the least number of repeated re-absorptions required for generating I-R is three.