Spectral broadening and enhanced ultra-broadband emission in Ca3TiTaGa3O12:Cr3+, Yb3+ co-doped phosphor for NIR pc-LED applications

Broadband near-infrared (NIR) phosphor-converted light-emitting diodes (pc-LEDs) are gaining significant interest due to their potential in spectroscopic applications. NIR phosphors play a critical role in pc-LED devices by converting visible light into NIR emission with high stability and tunability. In this study, an efficient broadband NIR phosphor, Ca 3 TiTaGa 3 O 12 :Cr 3+ , is developed and systematically investigated. Ca 3 TiTaGa 3 O 12 :Cr 3+ exhibits a broad NIR emission band centered at 790 nm with a full width at half maximum (FWHM) of 202 nm upon 450 nm blue light excitation. The emission bandwidth is further expanded to 303 nm by introducing an optimal amount of Yb 3+ co-doping, which produces a merged ultra-broadband Cr 3+ –Yb 3+ emission. Luminescence and decay kinetic analysis reveal that the resultant ultra-broadband emission originates from effective energy transfer Cr 3+ to Yb 3+ . Moreover, the Yb 3+ co-doping enhances the internal quantum efficiency from 30.5% to 41.3%, and improves thermal stability with emission retention increasing from 42.6% to 57.4% at 150 °C. The Ca 3 TiTaGa 3 O 12 :Cr 3+ and Ca 3 TiTaGa 3 O 12 :Cr 3+ , Yb 3+ phosphors are successfully integrated with a 450 nm blue LED chip, demonstrating their potential for practical NIR pc-LED device applications in night vision and bioimaging.