Surface Passivation of MAPbBr 3 Perovskite Single Crystals to Suppress Ion Migration and Enhance Photoelectronic Performance.

Recently, organometal halide perovskites (OHPs) have achieved significant advancement in photovoltaics, light-emitting diodes, X-ray detectors, and transistors. However, commercialization and practical applications were hindered by the notorious ion migration issue of OHPs. Here, we report a simple solvent-based surface passivation strategy with organic halide salts (methylammonium bromide (MABr) and phenylethylammonium bromide (PEABr)) to suppress the ion migration of MAPbBr 3 single crystals. The surface passivation effect is evidenced by the stronger photoluminescence (PL) intensity and extended PL lifetime. Using the pulse voltage and continuous voltage current-voltage measurements, we found that single crystals with surface passivation showed negligible hysteresis on the surface due to the suppression of ion migration. As a result, the dark current stability of coplanar structure devices was significantly improved. Moreover, the vertical structure X-ray detectors with PEABr treatment exhibited a high sensitivity of 15 280 μC Gy air -1 cm -2 and a low detection limit of 87 nGy air s -1 under 5 V bias. The proposed technology would be a versatile tool to improve the performance of perovskite photoelectronic devices.