Observation of electronic spectra modulation in a CH₃NH₃PbBr₃crystal by utilizing transient absorption microscopy

Organic-inorganic lead halide perovskite materials have attractive properties not only for solar cells but also for LED because of their high performance and wavelength tunability. Such an efficient light-emitting and lasing nature are indispensable for their applications, and the essential needs are miniaturization and low lasing threshold. One material that satisfies these requirements is lead halide perovskite. To understand the time evolution of the interaction between light and matter in a perovskite crystal system, it is necessary to reveal the carrier dynamics in each crystal. In this study, the transient absorption spectra of CH3NH3PbBr3 crystals were measured using a femtosecond transient absorption microscopy. Surprisingly, strong spectra modulation has been observed and these results indicate the charge separation on the surface of the crystal. Amplified spontaneous emission dynamics were also observed in the transient absorption spectra.