Cr3+-Yb3+ energy transfer drives ultra-wideband thermally-stable NIR-emitting Sr3Sc2Ge3O12 garnet phosphors for pc-LED application

The development of medical, military, and other fields has greatly increased the demand for broadband near-infrared light sources. This article reports that Sr3Sc2Ge3O12: Cr3+ (SSGO: Cr3+), a broadband near-infrared phosphor with 850 nm as the luminescence center, has an emission spectrum covering 700∼1200 nm and a full width at half maximum (FWHM) of 125 nm under 490 nm excitation. To further increase the FWHM value, Yb3+ is introduced into the phosphor of SSGO: Cr3+ to enable energy transfer from Cr3+ to Yb3+. After doping 1% of Yb3+ onto the Sr2+ site, the near-infrared emission generated by the 4A2→4T1(4P) transition of Cr3+ and the near-infrared emission generated by the 2F5/2→2F7/2 transition of Yb3+ work so that the FWHM increases to 220nm. In addition, the thermal stability of the phosphor after co-doping with Yb3+ is also greatly enhanced from 61.6% to 75.1% by comparing it to the Cr3+ single-doped sample. In addition, SSGO:0.08Cr3+, 0.01Yb3+ was combined with a commercial 490 nm chip to prepare a broadband near-infrared light-emitting diode (pc-LED).