Photoluminescence and Ce3+→Tb3+→Eu3+ Energy Transfer Processes of the Ce3+/Tb3+/Eu3+-doped β-NaYF4 Phosphors with Broadened Excitation Spectrum.

Ce³⁺/Tb³⁺ co-doped and Ce³⁺/Tb³⁺/Eu³⁺ tri-doped β-NaYF₄ photoluminescent microcrystals using oleic acid as surfactant were synthesized using the solvothermal method. Their microstructural characteristics and photoluminescence properties were investigated in detail. They have the shape of hexagonal prism bipyramids with uniform particle size, which decreases with the concentrations of Tb³⁺ and Eu³⁺. The energy transfer processes of both the Ce³⁺→Tb³⁺ and the Ce³⁺→Tb³⁺→Eu³⁺ were systematically studied. Compared with Eu³⁺ or Tb³⁺ single-doped β-NaYF₄ microcrystals, the sensitization by Ce³⁺ for the photoluminescence of Tb³⁺ and Eu³⁺ leads to a broad excitation spectral bandwidth in the ultraviolet (UV) range. Meanwhile, the corresponding optical absorption efficiency is greatly enhanced. High energy transfer efficiencies have been observed from Ce³⁺ to Tb³⁺ and from Tb³⁺ to Eu³⁺. [ABSTRACT FROM AUTHOR]