The recombination mechanisms leading to amplified spontaneous emission at the true-green wavelength in CH_3NH_3PbBr_3 perovskites

摘要

We investigated the mechanisms of radiative recombination in a CH_3NH_3PbBr_3 hybrid perovskite material using low-temperature, power-dependent (77 K), and temperature-dependent photolumi-nescence (PL) measurements. Two bound-excitonic radiative transitions related to grain size inho-mogeneity were identified. Both transitions led to PL spectra broadening as a result of concurrent blue and red shifts of these excitonic peaks. The red-shifted bound-excitonic peak dominated at high PL excitation led to a true-green wavelength of 553 nm for CH_3NH_3PbBr_3 powders that are encapsulated in polydimethylsiloxane. Amplified spontaneous emission was eventually achieved for an excitation threshold energy of approximately 350 μJ/cm~2. Our results provide a platform for potential extension towards a true-green light-emitting device for solid-state lighting and display applications.