Restricted growth and grain boundary reinforcement of MAPbBr3 film by graphene quantum dots with enhanced luminescence and stability

Organic-inorganic hybrid perovskite (OIHP) attracted much attention in the optoelectronic applications owing to its high yield, adjustable color and good mono-chromaticity. However, the defective sites at MAPbBr(3) film boundaries greatly jeopardize their luminescent property. In this study, graphene quantum dots (GQDs) are incorporated into the MAPbBr(3) film and pushed to the grain boundaries during perovskite crystallization via a modified freeze casting approach. The rich carboxyl groups of GQDs interact with the dangling lead atoms at grain boundaries, thus reducing non-radiative recombination centers within the film. On the other hand, GQDs create additional nucleation sites, which helps to form a uniformly covered luminescent film with small grains. As a result, the incorporation of GQDs increases the photoluminescence (PL) intensity of the emission film by about six times and well preserves the crystal phase for 36-day storage in ambient air.