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) 2 Cu 2 Br 4 and PPh 4 CuBr 2 single crystals, grown by the low-cost solution-processing method. By single-crystal X-ray diffraction refinement, the crystal structures of (Bmpip) 2 Cu 2 Br 4 and PPh 4 CuBr 2 were determined to be orthorhombic and monoclinic crystal systems, respectively. (Bmpip) 2 Cu 2 Br 4 and PPh 4 CuBr 2 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) 2 Cu 2 Br 4 and PPh 4 CuBr 2 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) 2 Cu 2 Br 4 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 air /s. Due to the combination of nontoxicity, long-term stability, and decent detection performance, (Bmpip) 2 Cu 2 Br 4 could be regarded as a promising X-ray scintillator.