Single Organic Cation Engineering Cu(I)-Based Ionic and Coordinate Type Halides as High-Efficiency Hydrogel...

Cu(I)-based halide scintillators are promising candidates for X-ray detection due to excellent scintillation and low-cost solution processability. However, the rational design of Cu(I)-based halide scintillators remains challenging due to insufficient theoretical frameworks elucidating their structure-property correlations. In this work, two Cu(I)-based hybrid metal halides, Cu₂I₄-IC (Ionic compound) are designed and Cu₄I₄-CC (Coordination compound) via bonding mode control engineering. The Cu₂I₄-IC exhibits blue emission, and the Cu₄I₄-CC exhibits yellow emission, and the photoluminescence quantum yield (PLQY) of Cu₂I₄-IC and Cu₂I₄-IC are 91% and 100% respectively. The non-radiative transitions are reduced due to the high rigidity of Cu₄I₄, resulting in a light yield up to 67 500 photons MeV^-1 and a detection limit as low as 47.3 nGy s^-1 of Cu₄I₄-CC. Additionally, a high-performance scintillator hydrogel based on Cu₄I₄-CC with polyvinyl alcohol (PVA),H₂O and dimethyl sulfoxide (DMSO) is innovatively developed. Owing to the high transmittance, the large-area scintillator hydrogel film (10 × 10 cm²) achieves an X-ray imaging resolution of 14 lp mm^-1. Furthermore, the synergistic effects of hydrogen bonding and coordination bonding endow the hydrogel scintillator with excellent plasticity and flexible stretchability. The Cu₄I₄-CC@PVA hydrogel proves promising for X-ray imaging with excellent stability in harsh environments, matching state-of-the-art scintillators.