Nanocrystals embedded in salt crystal hosts for scintillation.

Although conventional scintillators are commonly produced as large single crystals or doped inorganic hosts, semiconductor nanocrystals (such as quantum dots) have attracted growing interest as scintillator components owing to their size-tunable emission across the visible spectrum, fast emission lifetimes, and the potential to be incorporated into flexible or large-area detector geometries. Most prior work has embedded nanocrystals in organic polymer matrices or dissolved in solutions, but this approach is limited by the low atomic number (Z) of organic hosts and poor transport of radiation-generated charge carriers. Here is reported incorporation of CdSe/CdS core/shell quantum dots and other semiconductor nanocrystals into inorganic alkali halide salt crystal hosts including NaCl, NaBr, KBr, KCl, and NaI. Electron microscopy confirms the dispersion of nanocrystals throughout the host grains at loading densities above 1 volume percent. The resulting composites display spectrally pure photoluminescence, cathodoluminescence, and radioluminescence which is tunable with size and composition of the embedded nanocrystals. The solids retain rapid radioluminescence decay with weak afterglow and linear response with X-ray exposure. Scintillation imaging with QD-embedded KBr pellets demonstrates spatial resolution of at least 15 line pairs per millimeter in semitransparent pellets. Together, these results establish salt crystal hosts as a versatile, high-Z alternative to polymer matrices for nanocrystal-based scintillators.