Energy transfer mediated single-phased white light emission in Bi3+-Eu3+ codoped Ba3YGa2O7.5 for WLED

In this work, we provide a paradigm how to realize white light emission by utilizing the energy transfer from the Bi3+ to Eu3+ ions. First, a novel Bi3+ activated phosphor set of highly oxygen-deficient perovskite derivatives (Ba3YGa2O7.5, BYGO) were synthesized through the conventional high-temperature solid-state method. The crystal structure was confirmed by Rietveld refinement. Then, Eu3+ was introduced to the phosphor composition to construct energy transfer pathway with Bi3+. The emission color of the BYGO:Bi3+,Eu3+ phosphors can be changed from cyan to white and orange-red by altering the Bi3+/Eu3+ doping ratio. The energy transfer from the Bi3+ to Eu3+ ions was ascribed to dipole-dipole interaction. Finally, a single-component WLED device with a color-rendering index of 84.9 was successfully prepared by employing a near-ultraviolet chip and the BYGO:Bi3+,Eu3+ phosphors. This work not only indicates that the as-prepared BYGO:Bi3+,Eu3+ phosphors are a potential candidate for near-ultraviolet WLED, but also demonstrated that energy transfer is an avenue for single-phased white light emission.