Utilizing the energy transfer mechanism to realize color tunable luminescence

Abstract

Bi³⁺/Eu³⁺ co-doped phosphors can realize multi-color luminescence by adjusting the concentration ratio, which makes it possible to manually control the emission color. On this basis, a series of Bi³⁺/Eu³⁺ co-doped phosphors SrLaGa₃O₇:xBi³⁺,yEu³⁺ were prepared. The existence of energy transfer from Bi³⁺ to Eu³⁺ was verified by spectral analysis. The emission spectra of SrLaGa₃O₇:xBi³⁺ show a wide-band peaking at 472 nm. For SrLaGa₃O₇:xBi³⁺,yEu³⁺, the Bi³⁺ → Eu³⁺ energy transfer occurs and a series of sharp emitting peaks of Eu³⁺ can be observed simultaneously. The relative luminescence intensity of Bi³⁺ and Eu³⁺ can be modulated by changing the relative concentrations of Bi³⁺ and Eu³⁺. Using this mechanism, the color tunable luminescence of SrLaGa₃O₇:xBi³⁺,yEu³⁺ from cyan, through white to orange, and finally to red is realized. By using a 320 nm UV chip and SLG:0.06Bi³⁺,0.07Eu³⁺ white phosphor, a white light-emitting diode (WLED) lamp was fabricated with chromaticity coordinates of (0.3199, 0.3083) and a color rendering index R_a of 82. This indicates that the prepared sample is a very promising candidate in the LED field.