Intense green light emission in Sr 2 ZnGe 2 O 7 :Mn 2+ phosphors by the design of high symmetry melilite structure.

A green phosphor Sr 2 ZnGe 2 O 7 :Mn 2+ with melilite structure was prepared through high temperature solid-state reaction. When the 535 nm emission is monitored, the excitation spectrum of the Sr 2 ZnGe 2 O 7 :Mn 2+ contains two excitation bands in the ultraviolet area. When excited by UV light, the sample shows bright green emission at 535 nm, which corresponds to the distinctive transition of Mn 2+ ( 4 T 1 → 6 A 1 ). Moreover, the quantum efficiency of Sr 2 ZnGe 2 O 7 :Mn 2+ can reach up to 67.6%. Finally, a high-performance WLED with a low correlated color temperature of 4632 K and a high color rendering index (CRI) of 92.3 was packaged by coating commercial blue and red phosphors with optimized Sr 2 ZnGe 2 O 7 :Mn 2+ sample on a 310 nm UV chip. This indicates that Sr 2 ZnGe 2 O 7 :Mn 2+ has potential application as a green component in WLED lighting field.