Direct X-ray detectors made of zero-dimensional hybrid metal halide perovskite single crystals

Abstract

Zero-dimensional (0D) cadmium(Cd)-based A₂BX₄-type hybrid metal halide perovskites incorporating large sterically hindered cations define a new type of structure, which shows good performance in photoelectric detection because of their unique charge transmission. Herein, we report the synthesis of novel 0D (C₁₉H₁₈P)₂CdCl₄ single crystals (SCs) via a solution natural-volatilization method. Bulk (C₁₉H₁₈P)₂CdCl₄ SCs have sizes of 6 × 5 × 3 mm³. The as-synthesized SCs of (C₁₉H₁₈P)₂CdCl₄ exhibit a direct bandgap of 4.19 eV, possess a high resistivity of 3.73 × 10¹¹ Ω cm, and demonstrate a low stable dark current. The crystal showcases an observed mobility-lifetime (μτ) product on a scale of 10⁻⁴ cm² V⁻¹. Furthermore, an X-ray photoconductor was successfully fabricated based on the SC of (C₁₉H₁₈P)₂CdCl₄, which displays an outstanding sensitivity of ∼143.6 μC Gy_air⁻¹ cm⁻² when biased at 1000 V (333 V mm⁻¹), a response current with exceptional stability, and a stable baseline with the lowest dark current drift of 7.34 × 10⁻⁴ pA cm⁻¹ s⁻¹ V⁻¹. This work introduces a groundbreaking approach using single-crystal metal halide perovskites, opening up new possibilities for exploring optoelectronic applications, which holds the potential to unveil a novel generation of materials for X-ray detection and imaging.