Improvement of Stability and Optoelectronic Properties of Blue-Emitting Perovskite Nanoplatelets by Microwave Treatment

In this work, low-dimensional blue-emitting CsPbBr3 nanoplatelets were prepared. Changes in the surface morphology of NPLs after long-term storage in a humid environment were observed by transmission electron microscopy. The reason for the CsPbBr3 NPLs emission change from blue to green is found to be the loss of ligand and ion migration. Microwave treatment was demonstrated to improve the photostability and electrical stability of the samples. Based on the temperature-dependent and power-dependent photoluminescence measurement, it was concluded that both surface and internal defects of the sample decrease after microwave treatment. The ultrafast decay pathway of perovskite was thoroughly analyzed, and the ligand loss was found to be a deprotonation process, while the ion migration is a vacancy-driven and charge redistribution process. After microwave treatment, the residual polar DMSO solvent volatilizes, reducing the chance of structural collapse, and the surface and internal structural defects are reduced. In turn, the Br– ion can exist more stably on its surface. As a result, the defect migration pathway is reduced, and photostability and smaller magnitude photocurrent hysteresis can be obtained, which will provide an effective strategy for the optimization and stability improvement of blue-light optoelectronic devices.