Defects Repairing in Lead Tribromide Perovskites

The benign defect nature of iodide perovskites has gained strong momentum in understanding and application in perovskite devices, however the understanding of defects in bromide-based perovskites remains elusive. Here we demonstrate that biasing of lead bromide perovskite crystals can efficiently repair bulk point defects in them. The biasing results in a reduced defect density in the perovskite crystals, starting from cathode side and progressing into anode side across the whole crystals. Bromide vacancies, which are deep charge trapping defects in FAPbBr₃, are found to be swept away by the electrical bias, causing the formation of voids at the anode side of the crystals. The vacancies can diffuse back to the crystals during storage for days to weeks. We will also show that how we permanently repair these defects based on the understanding.