Modulation of photoluminescence intensity by surface defects of MAPbBr3 crystals

Abstract

MAPbBr3 single crystals have attracted much attention because of their high quantum efficiency and photoluminescence (PL) peaks. It has been researched that the crystal has two PL peaks and the additional PL peak comes from the “PbBr2” defect in the crystal. This can be well applied to dual-wavelength lasers. However, the change rule of the PL two peaks intensity is not clear. Herein. Crystals with two PL peaks are obtained by inverse temperature crystallization. We research the crystal structures of MABr and PbBr2 in different proportions, and find that these crystals have varying degrees of defects. Moreover, we confirm that these defects are Schottky defects based on experimental and simulated XRD. The optical properties of the samples are studied, which suggest that the PL intensity is related to the ratio of MABr to PbBr2. The energy level distribution of the crystal is calculated by energy level simulation, which further explains that the 536 nm is generated by “PbBr2” and the 567 nm is generated by MAPbBr3. All the results illustrate that the intensity of two peaks can be adjusted by the ratio of MABr to PbBr2. The maximum intensity is at 536 nm for MABr: PbBr2= 2 and 567 nm for MABr: PbBr2= 0.5. We explain this change rule of two peaks intensities from the energy level point of view and obtained MAPbBr3 crystals with high PL intensity corresponding to different wavelengths. This research provides a theoretical basis for the change in PL bimodal intensity, and an experimental reference for perovskite dual-wavelength laser.