Enhanced emission via energy transfer in RE co-doped SiO 2 –KYF 4 nano-glass-ceramics for white LEDs

Transparent RE doped and co-doped nano-glass-ceramics (RE = Ce3+, Tb3+, Eu3+) containing cubic KYF4 nanocrystals have been obtained by thermal treatment of precursor sol–gel derived glasses, and their luminescence properties were studied by emission and excitation spectra, supplemented with time-resolved measurements. For Ce3+–Tb3+–Eu3+ triply-doped nano-glass-ceramics with an adequate concentration of RE ions, white light generation was observed under ultraviolet excitation, via efficient energy transfer processes. The energy transfer mechanisms from Ce3+ to Tb3+ and Eu3+ ions were analyzed in terms of their corresponding energy level diagrams. The emitted color can be tuned by varying the content of Eu3+ ions and/or the excitation wavelength. These results suggest that this single-phased material might be a promising candidate for applications in UV-converting white LEDs.