Bright white light emission from lanthanide oxide LaGdO₃ for LED lighting by Bi³⁺ to Eu³⁺ energy transfer

Phosphors with intrinsic white light emission are of great potential in constructing high-quality white LEDs (WLEDs). In this work, we propose the use of energy transfer from Bi³⁺ to Eu³⁺ ions for white light emission. A unique Bi³⁺-activated phosphor LaGdO₃ (LGO):Bi³⁺ was generated using the conventional high-temperature solid-state process. An energy transfer was established by introducing Eu³⁺ into the phosphor composition. The emission colour of LGO:Bi³⁺,Eu³⁺ phosphors changes from cyan to white to orange-red depending on the Bi³⁺/Eu³⁺ doping proportion. The energy transfer between the Bi³⁺ and Eu³⁺ ions results from the dipole-dipole interaction. The LGO:Bi³⁺,Eu³⁺ phosphors were combined with a near-ultraviolet chip to successfully create a single-component WLED device with a colour-rendering index of 92.4. Our work demonstrates the energy transfer as a route for single-component white light emission and makes LGO:Bi³⁺,Eu³⁺ phosphors one of the candidate materials for near-ultraviolet lighting.