Abstract: A series of Bi³⁺/Eu³⁺ co-doped Zn₂GeO₄ phosphors （Zn₂GeO₄∶0.20Eu³⁺，xBi³⁺，x=0.05~0.30） were successfully synthesized via hydrothermal method.The phase structure， morphology， luminescent properties， and energy band regulation mechanism were systematically investigated using X-ray diffraction （XRD）， excitation/emission spectroscopy，scanning electron microscopy （SEM）， energy-dispersive X-ray spectroscopy （EDS）， and first-principles calculations.It was confirmed that both Eu³⁺ and Bi³⁺ were effectively incorporated into the Zn₂GeO₄ host lattice， with Eu³⁺ occupying Zn²⁺ sites， and no impurity phases were introduced by Bi³⁺ doping. First-principles calculations reveal that the Zn₂GeO₄∶0.20Eu³⁺，xBi³⁺ system possesses an indirect band gap， with the Fermi level （0.368 8 eV） crossing the conduction band， exhibiting near-metallic behavior， which enhanced the luminescence performance.At the optimal Bi³⁺ doping concentration of x=0.30，Bi³⁺ act as efficient sensitizers， transferring the absorbed ultraviolet light energy to the excited state energy levels （⁵D₂ and ⁵D₁） of Eu³⁺.This significantly enhances the excitation responses of Eu³⁺ at 384 nm （⁷F₀→⁵D₂） and 534 nm （⁷F₀→⁵D₁），as well as the characteristic red emission （⁵D₀→⁷F₂， 616 nm）.The phosphor possesses efficient red emission and tunable luminescence capabilities， providing new insights for the design of solid-state lighting materials.

Key words: germanate; phosphor; solid-state lighting; hydrothermal method; Eu³⁺/Bi³⁺ co-doping