Utilizing the energy transfer mechanism to realize color tunable luminescence.

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