A polar multilayered two-dimensional hybrid perovskite for self-driven X-ray photodetection with a low detection limit

Recently, two-dimensional (2D) organic-inorganic hybrid perovskites (OIHPs) with the general chemical formula of (A)2(B)n-1PbX3n+1 have garnered significant interest in optics and optoelectronics. Presently, the B-site cations in the perovskite cage are confined exclusively to small-size cations (such as Cs+ and CH3NH3+), while high-quality crystals of 2D OIHPs containing larger cations (e.g., guanidinium, G+) remain quite scarce for detecting X-ray application. Here, we have successfully fabricated a nanoGray-responsive self-driven X-ray detector using single crystals of a polar 2D hybrid perovskite, IA2GPb2I7 (where IA is isoamylammonium), of which G cations are confined inside the perovskite cages. The dynamic freedom of IA+ and G+ organic cations' molecular movements supplies the impetus for the creation of electrical polarization. Upon X-ray radiation, a bulk photovoltaic voltage of 0.74 V is generated due to the spontaneous electric polarization, which affords the source for self-driven detection. The grown high-quality inch-size crystals show high resistivity (1.82 x 1010 Omega cm) and huge carrier migration lifetime product (mu tau = 2.7 x 10-3 cm-2 V-1). As expected, an X-ray detector fabricated on high-quality crystals enables dramatic X-ray detection performances under 0 V, boasting an excellent sensitivity of 115.43 mu C Gyair-1 cm-2 and an impressively low detection limit of 9.6 nGyair s-1. The detection limit is superior to many known perovskite X-ray detectors. The investigation focuses on the rational design and engineering of new hybrid perovskites toward high-demand self-powered X-ray detectors. We have designed a polar multilayered hybrid perovskite by alloying large cations into the distorted cage, in which a crystal-based photodetector enables dramatic self-powered X-ray detection performance.