Intense green light emission in Sr2 ZnGe2 O7 :Mn2+ phosphors by the design of high symmetry melilite structure.

ABSTRACT

A green phosphor Sr2 ZnGe2 O7Mn2+ with a melilite structure was prepared using a high-temperature solid-state reaction. When the 535 nm emission was monitored, the excitation spectrum of the Sr2 ZnGe2 O7Mn2+ was found to contain two excitation bands in the ultraviolet (UV) region. When excited by UV light, the sample shows bright green emission at 535 nm, which corresponds to the distinctive transition of Mn2+ (4 T1 →6 A1 ). Moreover, the quantum efficiency of Sr2 ZnGe2 O7Mn2+ could reach 67.6%. Finally, a high-performance white-light-emitting diode (WLED) with a low correlated colour temperature of 4632 K and a high colour rendering index (CRI) of 92.3 were packaged by coating commercial blue and red phosphors with an optimized Sr2 ZnGe2 O7Mn2+ sample on a 310 nm UV chip. This indicated that Sr2 ZnGe2 O7Mn2+ has the potential application as a green component in the WLED lighting field.