Supplementary material

The schematic diagram and AFM image of p-GaN substrate; the cubic structure, TEM image and AFM image of CsPbBr3 perovskite QDs; side view, top view and fatbandstructure of CsPbBr3/GaN heterojunction; energy band diagram of CsPbBr3 and energy band diagram of GaN; heterojunction electron localization function; the function diagram of absorption coefficient and light energy of isolated GaN, CsPbBr3 and CsPbBr3/GaN heterojunction.