Broadband Near-Infrared Emitting Ca2LuScGa2Ge2O12:Cr3+ Phosphors: Luminescence Properties and Application in Light-Emitting Diodes

In recent years, the demand for near-infrared phosphor-converted light-emitting diodes (NIR pc-LEDs) has increased rapidly, leading to more and more attention being paid to the research of broad-band near-infrared phosphors. In this work, Cr³⁺-doped Ca₂LuScGa₂Ge₂O₁₂ (CLSGG:Cr³⁺) phosphors with broad-band NIR emission were prepared through traditional high-temperature solid-state reactions. The crystal structures of the phosphors were analyzed by X-ray diffraction (XRD) and Rietveld refinement. The photoluminescence excitation (PLE) spectra of the synthesized CLSGG:Cr³⁺ phosphors exhibit a strong absorption band in the 400-500 nm region, which matches well with a blue-light-emitting chip. The photoluminescence (PL) spectra of the phosphors show broad-band emission ranging from 650 to 1100 nm with a full width at half-maximum (fwhm) of about 150 nm. At 423 K, the integrated emission intensity of CLSGG:0.02Cr³⁺ is about 59% of that at room temperature. A NIR pc-LED device was fabricated by combining a mixture of as-synthesized CLSGG:0.02Cr³⁺ phosphor and silicone with a 460 nm blue-light-emitting chip. Under a driving current of 100 mA, the output power of the device can achieve 1.213 mW, indicating that the as-prepared phosphors are promising for NIR pc-LED applications.