Lead-Free Zero-Dimensional Organic-Copper(I) Halides as Stable and Sensitive X-ray Scintillators.

Low-dimensional organic-metal halides are regarded as an emerging class of X-ray scintillation materials, but most of the discovered compounds are confronted with challenges of toxicity and instability. To address these challenges, we herein report two lead-free zero-dimensional (0D) hybrid halides, (Bmpip)CuBr and PPhCuBr single crystals, grown by the low-cost solution-processing method. By single-crystal X-ray diffraction refinement, the crystal structures of (Bmpip)CuBr and PPhCuBr were determined to be orthorhombic and monoclinic crystal systems, respectively. (Bmpip)CuBr and PPhCuBr show broadband orange and yellow emissions peaking at 620 and 538 nm, respectively. Different from the emission nature of the recent reported Cu-based halide hybrids, both (Bmpip)CuBr and PPhCuBr emit from excitons bound to defects featuring spin-allowed transition, enabling them to possess fast scintillation decay time of tens of nanoseconds, respectively. In particular, the (Bmpip)CuBr single crystal has a high photoluminescence quantum yield of 48.2%, a high scintillation yield of 16,000 photons/MeV, and a low detection limit of 710 nGy/s. Due to the combination of nontoxicity, long-term stability, and decent detection performance, (Bmpip)CuBr could be regarded as a promising X-ray scintillator.