Fabrication of pyramidal (111) MAPbBr₃ film with low surface defect density using homogeneous quantum-dot seeds

Nucleation and seeding of organometal halide perovskite (OHP) films have been extensively investigated for forming high-density, large-crystalline, and low-defect films. In this study, CH3NH3PbBr3 (MAPbBr3) films with a low defect density are synthesized via a molecular exchange mechanism using MAPbBr3 quantum dots as seeds. The synthesized films exhibit a pyramidal morphology with a (111) crystal plane. The distribution of the (111) plane is controlled by adjusting the seed concentration. The pyramidal MAPbBr3 films exhibit improved photoluminescence intensity and uniformity compared with films produced using seedless toluene. When the seeds are employed, the surface trap density is reduced by a factor of 3.5, suppressing the photocurrent hysteresis and nonsaturated response of photodetectors. Additionally, the films formed using the seeds have improved stability owing to the chain decomposition reaction induced by electron beam heating.