Dy:Eu doped CaBAl glasses for white light applications

The combination of Eu³⁺ and Dy³⁺ in co-doped glassy materials provides interesting applicability for white light emission devices. In this work, Dy:Eu doped Calcium Boroaluminate (CaBAl) glasses were prepared by conventional melting quenching, with 3 wt% of Dy₂O₃ and Eu₂O₃ content varying from 0 to 3 wt%, and results of absorption spectra, photoluminescence and photoluminescence lifetime are discussed in terms of Eu₂O₃ content. The photoluminescence of the samples was studied under excitation of 365 and 405 nm light source. The 365 nm excitation shows favor to the Dy³⁺ ion emission. The results of photoluminescence lifetime at 575 nm (Dy³⁺) shows a decrease due to Eu₂O₃ addition, which suggests an energy transfer from Dy³⁺ (donor) to the Eu³⁺ (acceptor). On the other hand, under excitation of 405 nm, the photoluminescence lifetime at 575 nm (Dy³⁺) shows no significant changes due to Eu₂O₃ amount, which indicates that the energy transfer from Dy³⁺ to Eu³⁺ (under λ_exc = 405 nm) is negligible. However, the results of photoluminescence under 405 nm excitation present a white yellowish emission in the CIE diagram, which shifts to red with Eu₂O₃ addition. The combination of a Blue LED (BL) emission with the emission of the samples was also studied in the CIE diagram, in order to improve light emission and to obtain ideal White Light (WL). The results show that by modifying the emission intensity of BL, it is possible to achieve a route for smart lighting, close to the circadian light cycle.