Multi-color emission of Dy3+/Eu3+ co-doped LiLuF4 single crystals for white light-emitting devices

Here, the multi-color luminescence evolution in response to UV light excitation of Dy3+ singly doped and Dy3+/Eu3+ co-doped LiLuF4 single crystals were synthesized by a Bridgman method. Influence of Eu3+ ions concen-tration on the structural and spectroscopic properties of Dy3+/Eu3+ co-doped LiLuF4 single crystal were explored through optical absorption, their phase structure luminescence and decay measurements. Energy transfer from Dy3+ to Eu3+ ions is confirmed by the reduction of emission intensity and shortened decay time of Dy3+ ions, which is due to the resonant type via dipole-dipole interactions. Moreover, using the Dexter theory, the energy transfer microscopic parameters from Dy3+ to Eu3+ ions have been calculated. The characteristic emission color of the prepared crystal was examined by CIE 1931 chromaticity coordinates, and the corresponding correlated color temperature (CCT) value was estimated, indicating that neutral white light may be emitted from the single crystal. The emission color exhibits dependence on the Eu3+ concentration and the excitation wavelength. Furthermore, the practical. down-conversion internal quantum yield was measured by integrating spheres at about 10.96%. All these studies conclude that 1.7 mol% Dy3+/0.6 mol% Eu3+ ions incorporated single crystal is more suitable for neutral white light emitting applications. Also, the thermal quenching investigation suggests the Dy3+/Eu3+ co-doped LiLuF4 single crystals with excellent thermal stability show great potential for w-LED applications.