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

Abstract

Recently, two-dimensional (2D) organic–inorganic hybrid perovskites (OIHPs) with the general chemical formula of (A)₂(B)_n−1PbX_3n+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 × 10¹⁰ Ω cm) and huge carrier migration lifetime product (μτ = 2.7 × 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 μC Gy_air⁻¹ cm⁻² and an impressively low detection limit of 9.6 nGy_air 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.