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.