Solvent-Induced Oriented FAPbI3 Single Crystals towards Highly Efficient Self-Powered X-ray Detectors

Abstract

Perovskites are promising applied in self-powered X-ray detectors. However, the prone defects cause unsatisfactory sensitivity for the prepared devices. Tuning crystal orientation has been confirmed as an effective mean to restrain the defects of perovskites. Here, we report the co-development of (100), (110) and (111) crystal orientations in FAPbl3 SCs for the first time by inducing the target facets to be the lowest surface energy facets within the selected solvents. The size of the formed facets is large enough to evaluate their properties without interference from non-dominant facets. Compared to (110)- and (111)-oriented FAPbI3 SCs, the (100)-oriented one manifests reduced trap-state density and suppression of ionic migration. It thus promotes charge collection, demonstrating superior response performance under both visible-light and X-ray illuminations. Moreover, such orientation engineering enables FAPbI3 SCs to be excellent candidates for self-powered X-ray detectors. High sensitivity close to 5000 μC Gyair-1 cm-2 was achieved when using 30 keV of X-ray energy, which is the record value in all the self-powered X-ray detectors constructed exclusively by perovskites, even surpassing the devices assisted by heterojunctions. Hence, our findings confirm that solvent-induced orientation engineering has great potential to promote perovskite SCs to be the superior choices for the self-powered X-ray photodetectors with high performance.