CaLu2Sc2Al2SiO12:Ce3+ Green Phosphors for High-Quality White LEDs

Phosphors with broadband green emission are highly desirable for the construction of high-color-rendering warm-white light-emitting diode (LED) devices toward healthy solid-state lighting applications. However, most of the reported green phosphors are subject to an undesirable emission bandwidth and low quantum efficiency. Here, a highly efficient broadband green-emitting garnet phosphor, CaLu₂Sc₂Al₂SiO₁₂:Ce³⁺ (CLSASO:Ce³⁺), is successfully synthesized and investigated in detail. Upon excitation of 440 nm blue light, the as-synthesized CLSASO:3%Ce³⁺ phosphor features a wide bandwidth with a maximum peak situated at 534 nm and a large full width at half-maximum (fwhm) of 114 nm, which is superior to the commercial green phosphor of LuAG:Ce³⁺ (fwhm = 108 nm). As expected, the optimal CLSASO:3%Ce³⁺ sample also demonstrates satisfactory internal/external quantum efficiency of 78.3/50.1%, along with suitable CIE color coordinates of (0.3462, 0.5496). Meanwhile, temperature-dependent emission spectra measurements indicate that it retains 46% of the original integral intensity at 423 K against room temperature, together with an excellent color stability of 9.2 × 10^-3. Finally, a fabricated blue-light-pumped prototype LED device with the proposed CLSASO:3%Ce³⁺ green component and another commercial CaAlSiN₃:Eu²⁺ red phosphor delivers a brilliant warm-white light with a desirable color rendering index (Ra = 90.2), an acceptable color temperature of 4047 K and a superior luminous efficiency of 65.6 lm W^-1. The findings illustrate that the construction of blue-light-excitable broadband green luminescence conversion material is beneficial for the preparation of a high-color-rendering warm-white LED device for high-quality general lighting applications.