Size-dependent one-photon- and two-photon-pumped amplified spontaneous emission from organometal halide CH3NH3PbBr3 perovskite cubic microcrystals.

In the past few years, organometal halide light-emitting perovskite thin films and colloidal nanocrystals (NCs) have attracted significant research interest in the field of highly purified illuminating applications. However, knowledge of photoluminescence (PL) characteristics, such as amplified spontaneous emission (ASE) of larger-sized perovskite crystals, is still relatively scarce. Here, we presented room-temperature size-dependent spontaneous emission (SE) and ASE of the organometal halide CH3NH3PbBr3 perovskite cubic microcrystals pumped through one-photon-(1P) and two-photon-(2P) excitation paradigms. The results showed that the optical properties of SE and ASE were sensitively dependent on the sizes of perovskite microcrystals irrespective of whether 1P or 2P excitation was used. Moreover, by comparing the spectral results of 1P- and 2P-pumped experiments, 2P pumping was found to be an effective paradigm to reduce thresholds by one order of magnitude. Finally, we carried out fluences-dependent time-resolved fluorescence dynamics experiments to study the underlying effects of these scale-dependent SE and ASE. We found that the photoluminescence (PL) recombination rates sensitively became faster with increasing carriers' densities, and that the ASE pumped from larger-sized CH3NH3PbBr3 perovskite cubic microcrystals showed faster lifetimes. This work shows that micro-sized perovskite cubic crystals could be the ideal patterns of perovskite materials for realizing ASE applications in the future.