Investigation of multicolor emitting Cs 3 GdGe 3 O 9 :Bi 3+ ,Eu 3+ phosphors via energy transfer for WLEDs.

Bi 3+ /Eu 3+ doped Cs 3 GdGe 3 O 9 luminescent materials were prepared by a solid-state reaction. The energy band and density of states of Cs 3 GdGe 3 O 9 were calculated by density functional theory. The Cs 3 GdGe 3 O 9 host presents a broadband emission peaking at 520 nm. Systemic measurement and analysis of luminescence properties were performed to confirm the energy transfer in Cs 3 GdGe 3 O 9 :Bi 3+ ,Eu 3+ . The multicolor modulated emission from blue (0.1678, 0.1568) to red (0.5931, 0.3251) can be achieved by varying the doping ratio of bismuth to europium. A white light-emitting diode (WLED) was produced by combining the Cs 3 GdGe 3 O 9 :0.05Bi 3+ ,0.1Eu 3+ phosphor, a commercial green phosphor, and a 310 nm ultraviolet chip. The color rendering index of the WLED driven by 20 mA bias current is 89.6 with the CIE coordinates of (0.3520, 0.3626). The results reveal that the Cs 3 GdGe 3 O 9 :Bi 3+ ,Eu 3+ phosphor is a potential material that can be used in multicolor tunable luminescence and WLEDs.