Two-Dimensional Copper(II)-Based Perovskite Single Crystals for Sensitive X-ray Detection

Lead halide perovskites have garnered significant attention as promising materials for direct X-ray detection due to their exceptional optoelectronic properties, which enable high sensitivity and efficiency. However, the environmental and biological risks associated with lead-based compositions limit their practical application, necessitating the development of lead-free alternatives. In this work, a novel two-dimensional (2D) copper(II)-based perovskite, (t-ACH)₂CuBr₄ (t-ACH = trans-4-(aminomethyl)cyclohexanecarboxylic acid), is synthesized to yield high-quality single crystals with dimensions of up to 14 × 8 × 1 mm³, exhibiting exceptional X-ray detection performance. The bifunctional organic cation, containing both ammonium and carboxylate groups, facilitates robust N–H···Br and O–H···O hydrogen bonding, reinforcing interlayer coupling and enhancing structural stability. A vertical Au/(t-ACH)₂CuBr₄/Au X-ray detector exhibits high sensitivity of 65.9 μC Gy_air^–1 cm^–2, low dark current drift of 2.367 × 10^–6 nA cm^–1 s^–1 V^–1, and excellent operational stability. These results highlight the potential of hydrogen-bond-stabilized, ecofriendly copper halide perovskites for next-generation, sustainable X-ray detection technologies.