Ce3+ doped BaLu2Al2Ga2SiO12 — A novel blue-light excitable cyan-emitting phosphor with ultra-high quantum efficiency and excellent stability for full-spectrum white LEDs

Abstract

It is well known that cyan-emitting phosphors play a very important role in full-spectrum white LEDs. A large number of cyan-emitting phosphors have been reported in the past few years, however, most of them can only be effectively excited by near-ultraviolet light. There are very few cyan-emitting phosphors that can be intensively excited by blue light (440 and 470 nm). Here, a novel blue-light excitable cyan-emitting phosphor BaLu1.95Ce0.05Al2Ga2SiO12 with excellent performance is reported. The cyan phosphor has a cubic structure in space group Ia3¯d with a = 1.205379(3) nm, which can be easily obtained through a solid-state reaction pathway. The emission peak of the cyan phosphor is located at 500 nm and its internal quantum efficiency is as high as 90.01% when excited at 455 nm at 25 °C. The cyan phosphor exhibits superior resistance against thermal quenching of luminescence, and its intensity at 125 °C is as strong as 92.14% of the intensity at room temperature. Meanwhile, it also shows an outstanding resistance against water, where its luminescence intensity is hardly changed after being immersed in pure water for 528 h. The white LED lamp prepared by employing the obtained BaLu1.95Ce0.05Al2Ga2SiO12 as cyan phosphor displays remarkable optical properties with CCT = 4441 K, Ra = 93.7, CRI = 90.4 and CIE 1931 (x, y) as (x = 0.3648, y = 0.3752). The experimental results demonstrate that BaLu1.95Ce0.05Al2Ga2SiO12 is a promising cyan-emitting phosphor with great application potential in full-spectrum white LEDs.