Polar Multi-layered Two-Dimensional Hybrid Perovskite for Self-driven X-ray Photodetection with Low Detection Limit

Recently, two-dimensional (2D) organic-inorganic hybrid per-ovskites (OIHPs) have gar-nered significant interest of optics and optoelectronics. Presently, the “perovskitizer” moieties 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 cation (e.g., guanidinium, G+) cation as perovskitizer remain quite scarce for detecting X-ray application. Here, we have successfully fabricated nanoGray-responsive self-driven X-ray detector using single crystals of a polar 2D hybrid perovskite, IA2GPb2I7 (where IA is isoamylammoni-um), of which G cations are confined inside the perovskite cages. The dynamic freedom of IA+ and G+ organic cations' molecular movements sup-plies the impetus for the crea-tion of electrical polarization. Upon X-ray radiation, a bulk photovoltaic voltage of 0.74 V is generated due to the spon-taneous electric polarization, which affords the source for self-driven detection. The grown high-quality inch-size crystals show high resistivity (1.82 × 1010 Ω cm) and huge carrier migration lifetime product (μτ = 2.7×10-3 cm-2 V-1). As expected, X-ray detector fabricated on high-quality crystal enables dramatic X-ray detection performances un-der 0 V, boasting an excellent sensitivity of 115.43 μC 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 investiga-tion focuses on the rational design and engineering of new hybrid perovskites to-ward high-demanded self-powered X-ray detector.