Color-Tunable Broadband Chiral Copper(I) Halides Scintillators for High-Resolution X-Ray Polarization Imaging

Utilizing the circularly polarized luminescence (CPL) of scintillators offers a distinct advantage for X-ray imaging, as it significantly reduces optical crosstalk. Herein, we propose an effective strategy of crown ether-assisted self-assembly combined with halogen regulation to construct two novel pairs of isostructural chiral copper(I) halide clusters: R/S-Br and R/S-I. Under X-ray or UV light excitation, R/S-Br exhibits red broadband emission with a photoluminescence quantum yield (PLQY) of 77.0%, time-resolved PL (TRPL) decay time of 35.8 µs, and scintillation light yield (LY) of 5819 photons/MeV. In contrast, R/S-I displays yellow-green broadband emission with a near-unity PLQY, TRPL decay time of 2.86 µs, and a high LY of 14389 photons/MeV. The CPL asymmetry factor of S-Br and R-I is 1.23 × 10^-2 and 1.72 × 10^-3, respectively. Consequently, S-Br-based and R-I-based LEDs, along with near-infrared imaging systems, demonstrate exceptional chiral optical selectivity. When using an X-ray polarization optical system, the imaging resolution of the S-Br scintillator increased from 9 to 20 lp/mm, while that of the S-I scintillator improved from 16 to 25 lp/mm, with a detection limit of 3.15 µGy/s. Besides, the relationship between optical performance and structural/heavy atom effects, along with optimization mechanisms, was clarified, offering a facile strategy for high-resolution, color-tunable scintillators.