Designing and controlling the Ni2+-activated (Zn, Mg)Al2O4 spinel solid-solution for phosphor-converted broadband near-infrared illumination

Abstract

The strategy of using near-ultraviolet (UNV) or blue chips to excite phosphors and enable continuous broadband near-infrared (NIR) emission is ideal for new-generation NIR illumination light sources. Therefore, it has become extremely urgent to develop broadband NIR emitting phosphors to realize the application of phosphor-converted NIR light-emitting diodes (pc-NIR-LEDs). Here, Ni²⁺-activated NIR phosphor Zn_1−xMg_xAl₂O₄ solid-solution was synthesized by a high-temperature solid state reaction method. The optimum phosphor with a broadband NIR emission band of 1000–1600 nm and a full-width half maximum (FWHM) of 232 nm was obtained. Structural results indicate that the substitution of Mg²⁺ for Zn²⁺ in the spinel host leads to the change in the bond length and angle in the [NiO₆] octahedron and adjustable emission at 1201–1251 nm in the NIR region under excitation by UV light at 365 nm. The optimized phosphor was encapsulated in NUV LED chip to obtain pc-NIR LED device, and the application of broadband pc-NIR LED lighting was achieved. In addition, the optimum NIR phosphor exhibits luminescence stability without reaching luminescence saturation when coupled with a λ = 360 nm laser, resulting in great potential application in laser-driven NIR illumination.