Spectroscopic investigation of near-infrared luminescence and energy band structure in Cr3+-doped BaGa2O4

s Cr 3+ activated broadband Near-Infrared (NIR) fluorescent phosphors with octahedral coordination preference and their potential applications in biomedicine, plant growth, etc. However, the development of Cr 3+ -doped broadband NIR fluorescent phosphors with tetrahedral coordination remains a challenge. This study, for the first time, employs first-principles calculations to investigate the doping sites of Cr 3+ in a tetrahedral coordination environment. It confirms the possibility of tetrahedral coordination for Cr 3+ and determines the doping sequence of Cr 3+ through the calculation of formation energies. The energy band structure of BaGa 2 O 4 :Cr 3+ has been calculated for the first time, and the orbital distribution of the Cr 3+ impurity energy level has been calculated by mBJ correction, which is in good agreement with the experimentally derived spectral leaps. The emission peak of BaGa 2 O 4 :Cr 3+ phosphor is located at 711 nm. XPS tests were conducted to determine the valence state of Cr ions in the lattice of BaGa 2 O 4 :Cr 3+ , confirming the presence of Cr 3+ ions responsible for NIR luminescence in BaGa 2 O 4 :Cr 3+ . Thermal stability tests were performed, showing that the thermal stability can reach 66.46% at 425 K under ambient conditions when single-doped with Cr 3+ , representing a significant improvement compared to other tetrahedrally coordinated Cr 3+ dopants. This provides possibilities for the application of Cr 3+ in tetrahedral coordination as near-infrared fluorescent phosphors for LEDs.