Accessing energy-efficient broadband near-infrared luminescence in Cr3+-doped disordered garnet with near-zero thermal quenching and an EQE of 50.26 %

The ever-increasing demand for portable near-infrared (NIR) light sources has presented significant challenges in the development of highly efficient and thermally stable NIR phosphors. To address this challenge, we have employed a cation-substitution strategy. we incorporated indium (In) and gallium (Ga) atoms into the B-sites of the garnet-host lattice in a 1:1 M ratio. Through strategic placement of In and Ga atoms at octahedral sites, an order-disorder transition was induced. This innovative method has significantly improved the phosphor's performance characteristics. The optimized Cr³⁺-doped gadolinium indium gallium garnet (GIGG) exhibits an emission peak at 770 nm with a maximum full width at half-maximum (FWHM) value of 135 nm. Its internal quantum efficiency (IQE) reaches 96.17 %, while the external quantum efficiency (EQE) for this garnet-based material achieves 50.26 %. Furthermore, at 423 K, the material's luminescence intensity remains at 96.44 % of its initial value, demonstrating remarkable thermal stability. These characteristics render it an ideal candidate for energy-efficient down-conversion layers in photonic devices. In follow-up investigations, a NIR phosphor-converted light-emitting diode (pc-LED) fabricated using the optimized GIGG:Cr³⁺ delivered a NIR output power of 241.04 mW under 960 mA drive current and achieved a photoelectric conversion efficiency (PCE) of 15.25 % at 30 mA, thus demonstrating its suitability for various photonic applications. This study presents an efficient broadband NIR garnet-based phosphor and provides new opportunities for advancing next-generation, energy-efficient, and compact solid-state NIR light sources.