Spectroscopic performance enhancement in GAGG:Ce scintillator via CsPbBr3 quantum dot and PMMA surface coatings

초록

Scintillation detectors are widely used for gamma-ray spectroscopy, but their energy resolution remains inferior to that of semiconductor detectors. Although perovskite quantum dots (QDs) show promise for radiation detection, their impact on practical spectroscopic performance has not been systematically evaluated. Here, CsPbBr3 QD–polymethylmethacrylate (PMMA) composite coatings were applied to a cerium-doped gadolinium aluminum gallium garnet (GAGG:Ce) scintillator, and performance was assessed using 137Cs and 60Co sources over QD concentrations from 1 to 4 wt%. At optimal loading, energy resolution and peak-to-valley ratio improved significantly. Control experiments with PMMA-only coating degraded performance, confirming that the enhancements arise from the QDs rather than polymer matrix effects. Mechanistic analysis showed that conventional photophysical processes, such as Förster resonance energy transfer, direct scintillation, and wavelength shifting, cannot fully account for the observed improvements. These mechanisms are expected to contribute minimally or potentially degrade performance. Instead, the evidence suggests that passive optical effects are the most plausible contributors to the enhancement, with crack-related modifications of the coating surface structure providing a consistent interpretation. The pronounced concentration dependence, characterized by optimal performance at intermediate loading and degradation at higher concentrations, further supports a structural rather than photophysical origin. This study indicates that perovskite QD coatings can significantly improve the spectroscopic performance of scintillation detectors and establishes a foundation for further structural optimization strategies in radiation detection applications.

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