Hybrid cuprous halides have attracted great attention in optoelectronic fields due to their low cost, abundant structural diversity, and highly efficient luminescence. However, there have been ambiguous issues about the crystal structure and photoluminescence characteristics of morpholinium cuprous bromide. Here, hydrogen bonding induced a synergistic effect on second-harmonic generation and highly efficient photoluminescence of hybrid cuprous halides was observed. Morpholinium cuprous bromide dihydrate (mor4Cu2Br6·2H2O) single crystals were grown in HBr/CH3CN and H3PO2 solution by a slow evaporation method. Interestingly, mor4Cu2Br6·2H2O exhibited the triclinic crystal system P1 (no.1), which showed the obvious second-harmonic generation effect of 4 × Y-cut quartz. More importantly, mor4Cu2Br6·2H2O showed highly efficient photoluminescence (PL) located at about 560 nm with a photoluminescence quantum yield (PLQY) of 83.68% attributed to the through space charge transfer (TSCT) mechanism, which clarified the controversial results about the former crystal structure and PLQY exceeding 100% in hybrid cuprous halide systems. Besides, the preliminary anticounterfeiting of these hybrid cuprous bromide and iodide hydrates was demonstrated. This work not only provides the understanding for the structure-property relationship of hybrid cuprous halides, but also paves the way for optoelectronic device design and fabrication of the hybrid cuprous halide systems.
Sang et al. (2026) studied this question.