Photoluminescence properties of a new red-emitting Mn-activated ZnGa2S4 phosphor

A series of Zn1−xGa2S4:xMn2+ (0.005 ≤ x ≤ 0.08) phosphors has been synthesized by solid-state reaction at 950 °C for 2 h in a flowing H2S stream. The structural and photoluminescence properties of Zn1−xGa2S4:xMn2+ phosphors have been investigated. Under an excitation wavelength of λex = 336 nm, ZnGa2S4:Mn2+ exhibits a red emission band at about 612 nm owing to the Mn2+4T1(4G) → 6A1(6S) transition. The luminescence band shifts to longer wavelength and is accompanied by a decrease in decay time with increasing Mn2+ concentration. The maximum PL intensity of the phosphor is obtained at x = 0.03. The critical transfer distance of Mn2+ is calculated as 21 Å. The decay time for ZnGa2S4:0.03Mn2+ is 1.79 ms. The calculated CIE coordinates indicate that ZnGa2S4:Mn2+ has good color purity. Mn2+-activated ZnGa2S4 phosphors have great potential for application in UV white LED and display devices.

The colors of all of the ZnGa2S4:xMn2+ phosphors are located in the red region. Point (a) is superior to point (b) in color saturation. Therefore, the white emission with CIE coordinates (x = 0.33, y = 0.33) can be achieved by connecting only two points, i.e., combining the ZnGa2S4:xMn2+ phosphor and some suitable bluish green phosphor that has CIE coordinates (x ≈ 0.20, y ≈ 0.30).Figure optionsDownload as PowerPoint slideHighlights
► A new thiogallate red-emitting ZnGa2S4:Mn2+ phosphor has been synthesized.
► Their structures, luminescent properties have also been investigated.
► ZnGa2S4:Mn2+ exhibits a red emission band at about 612 nm with a FWHM of 76 nm.
► The calculated CIE coordinates indicates ZnGa2S4:Mn2+ has good color purity.