Highly efficient and stable near-infrared broadband luminescence in SrGa4O7:Cr3+, Yb3+ phosphor

Developing novel broadband near-infrared (NIR) phosphors is crucial to promote NIR phosphor-converted light emitting diodes (pc-LEDs) development. In this paper, a novel multifunctional near-infrared phosphor, SrGa 4 O 7 :Cr 3+ , Yb 3+ , was synthesized by the conventional high-temperature solid-state method. The emission band of the material spans from 650 nm to 1100 nm. Despite the predominance of four-coordinate and five-coordinate sites within the SrGa 4 O 7 (SGO) lattice, the incorporation of Cr 3+ ions induces distortion in the Ga–O tetrahedra, resulting in an octahedral environment for Cr 3+ . Under blue light excitation, the Cr 3+ ions exhibit an ultra-wide emission band (650–900 nm) with a Full Width at Half Maximum (FWHM) of 131 nm. Furthermore, energy transfer from Cr 3+ to Yb 3+ was achieved in SrGa 4 O 7 :Cr 3+ , Yb 3+ , and the incorporation of an optimal quantity of Yb 3+ co-dopant yielded a significantly enhanced and extraordinarily broad spectrum from 600 to 1100 nm. Moreover, Yb 3+ -codoping improves the thermal stability due to the energy transfer from Cr 3+ to more thermally stable Yb 3+ emitters, and the integrated intensity of SrGa 4 O 7 :Cr 3+ , Yb 3+ at 300 K was 74% of that at room temperature. Based on these findings, a blue-light-excited NIR pc-LED was encapsulated. The forward voltage and intensity of the LED remained almost constant after 500 h of thermal aging at high temperatures, indicating its particular reliability in NIR pc-LED applications. The results show that SrGa 4 O 7 :Cr 3+ , Yb 3+ phosphors have great potential in ultra-wideband NIR pc-LED applications.