Record-High Photoluminescence Efficiency and Excellent Scintillation in Two-Dimensional Diamine Hybrid Copper(I) Halides

To date, Cu(I)-based metal halides with high photoluminescence quantum yields (PLQYs) have primarily focused on their zero-dimensional or one-dimensional structures, significantly reflecting the charge or carrier localization. Designing two-dimensional (2D) hybrid copper(I) halides remains a significant challenge for optoelectronic applications, particularly in simultaneously achieving high PLQY and exceptional structural stability. Here, we report a novel series of 2D hybrid Cu(I) halides, (TDMP)Cu 2 X 4 (TDMP = 2,5-dimethylpiperazine and X = Cl, Br), synthesized through simple solution-cooling crystallization methods. (TDMP)Cu 2 Cl 4 and (TDMP)Cu 2 Br 4 emit cyan and blue light with PLQYs of 94.3 and 71.7%, respectively. According to the literature, the 94.3% represent the highest PLQYs reported for 2D Cu(I)-based hybrid materials. Interestingly, (TDMP)Cu 2 Cl 4 demonstrates excellent water stability, retaining its efficient emission properties even after prolonged exposure to water. Furthermore, the scintillation screen based on (TDMP)Cu 2 Cl 4 exhibits promising X-ray scintillation performance, with a low detection limit of 127 nG air y s –1 and a high resolution of 16.5 lp mm –1, significantly outperforming commercially available materials. This study provides a strategy for designing high-performance 2D Cu(I)-based metal halides and X-ray imaging materials.