Ultrabroadband Visible–Near-Infrared Phosphor CaY2Mg2Ge3O12:Ce3+/Cr3+ and Its Temperature Sensing

With the wide application of phosphor conversion light-emitting diode (pc-LED) in nondestructive testing, spectral illumination, near-infrared (NIR) spectroscopy, agricultural medical care, and other fields, the ultrabroadband visible–NIR tunable emission phosphor is considered as the most promising fluorescent material. In this paper, Ce³⁺/Cr³⁺ single-doped and codoped CaY₂Mg₂Ge₃O₁₂ phosphors were successfully prepared by using the high-temperature solid-state method. Ce³⁺ and Cr³⁺ codoped phosphors show ultrabroadband visible–NIR emission from 480 to 900 nm with two emission peaks at visible 556 nm and infrared 758 nm. Interestingly, energy transfer and occupation competition are shown in the Ce³⁺/Cr³⁺ codoped CaY₂Mg₂Ge₃O₁₂. Additionally, the luminescence of Ce³⁺/Cr³⁺ codoped CaY₂Mg₂Ge₃O₁₂ is adjusted with the doping ion concentration or ambient temperature changes. The energy transfer mechanism of Ce³⁺–Cr³⁺ is studied according to Dexter’s formula, and a dipole–dipole interaction is determined. Furthermore, its superior sensitivity with S_r of 1.331%K^–1 at 298 K was calculated by using the fluorescence intensity ratio. The pc-LED device was fabricated by combining a commercial 460 nm blue LED chip with CaY₂Mg₂Ge₃O₁₂:Ce³⁺, Cr³⁺ phosphors, producing yellow-white light and broadband NIR light, indicating great potential application in night vision pc-LEDs.