Mechanisms driving aging-induced property changes in water-based CdS/ZnS quantum dots scintillators

Determine the physical and chemical mechanisms responsible for the time-dependent changes observed in water-dispersed oleic-acid-encapsulated CdS/ZnS quantum dots (WbQD) liquid scintillator samples—specifically, the variations in photoluminescence quantum yield, hydrodynamic size, and zeta potential over one to two years post phase-transfer—given that absorption and emission spectra remain essentially unchanged during this period.

Background

For reactor-neutrino and other long-duration particle-physics applications, stability of scintillation performance over years is critical. The authors prepared three water-based CdS/ZnS quantum dot (QD) samples via oleic-acid-based phase transfer (2021, 2022, and 2023) and monitored optical and physical properties.

While absorption and emission spectra remained stable without measurable shifts, the photoluminescence quantum yield (PLQY) changed significantly over time in opposite directions for different batches. Concurrently, hydrodynamic size tended to decrease modestly and zeta potential values evolved, suggesting surface-level changes (e.g., surfactant layer reorganization) rather than core modifications. However, the precise causes of these changes could not be identified from the available data, leaving the underlying mechanisms unresolved.