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.