Performance Enhancement of All-Inorganic Perovskite Quantum Dots (CsPbX3) by UV-NIR Laser Irradiation

Perovskite quantum dots (QDs) have gained significant attention for both fundamental research and commercial applications because of their outstanding optoelectronic properties and tremendous application potentials. Reducing defect density in all-inorganic perovskite QDs is of great importance for performance enhancement. In this work, it is found that the UV-NIR femtosecond laser pulse treatments could increase the photoluminescence quantum yield (PLQY) of the CsPbBr3 perovskite QDs from 71 to 95%. Such an enhancement could be attributed to decrease of the defects after laser exposure, which is consistent with its red-shifted PL and other characterization results. Furthermore, the dynamics of energy transfer from exciton to trapping in irradiated CsPbX3 QDs are studied to gain an insight into the relative strength of exciton-trapping exchange coupling. The results confirm that the trapping defects are decreased by laser irradiation, and the mechanism leading to the enhancement of PLQY is revealed. In addition, the enhanced stability of laser-irradiated CsPbX3 QDs is also testified. Finally, the application of laser-treated perovskite QDs in the liquid crystal display (LCD) backlight film is successfully demonstrated. It is further anticipated that this mechanism is helpful for the design of perovskite-based optoelectronic applications such as LCD technology and light-emitting devices.