Eu^3+ doped yttrium oxysulfide quantum structures—structural, optical and electronic properties

Small particles of trivalent europium doped yttrium oxysulfide nanocrystals ((phi)~ 7 nm) were synthesized using sol–gel polymer thermolysis. The nanocrystals show significant change in the excitation bands corresponding to fundamental absorption and charge transfer absorption bands. The optical spectra essentially comprise of two parts: fundamental absorption (~260 nm) and Eu^3+–X^2- ligand (O2-/S2-) charge transfer (~290 nm) bands. They show significant blue shifts (0.24–0.30 eV), respectively, with respect to the bulk counterpart. These may be explained by considering possible size dependent changes associated with quantum confinement effect in this large bandgap semiconductor system. FT-IR spectra revealed the difference in chemisorbed species between bulk and nanocrystalline samples. The results of the solid-state photoinduced electrical impedance spectroscopy studies are reported.