Mild preparation and high fluorescence emission efficiency of europium-doped gallium nitride nanocrystals and first-principles density functional theoretical analysis of optical properties

Europium-doped gallium nitride (Eu:GaN) nanocrystals with hexagonal wurtzite structures were prepared from the decomposition of the EuxGa1-x(H2NCONH2)(6)Cl-3 precursor at a mild temperature of 350 degrees C. The absorption spectrum, the excitation spectra and the fluorescence emission spectra of Eu:GaN nanocrystals are measured and discussed. Eu:GaN has a strong fluorescence emission band in the visible region. Furthermore, the first-principles density functional theory has been adopted to explore the fluorescence mechanism. The results show that energy transfer should occur between the GaN host and Eu3+ ions under excitation at 370 nm, and thus the fluorescence emission efficiency of the Eu3+ ions can be improved. In order to further reduce the loss of fluorescence emission and increase the fluorescence quantum yield, Eu:GaN nanocrystals coated by biocompatible silica and dispersed in ethanol are also discussed.