Y2O2S:Eu3+ nanocrystals, a strong quantum-confined luminescent system

Trivalent europium-doped yttrium oxysulfide nanocrystals synthesized using sol–gel thermolysis show significant blue shifts in the excitation bands corresponding to fundamental absorption, charge-transfer absorption. A significant blue shift observed in the fundamental absorption edge for the nanocrystals having an average crystallite size (φ) in the range 9–15 nm indicates a strong quantum confinement with a Bohr exciton radius of 5–13 nm. Also, the diffuse reflectance spectra and the corresponding Kubelka–Munk plot indicate the possibility of profound decrease in the absorption coefficient of Eu3+–ligand charge-transfer species necessitating further studies in this wide-gap semiconductor nanocrystalline system.