Broadband near infrared luminescent properties of Cr3+ activated SrGa2Si2O8 phosphor

There has been a lot of interest in trivalent chromium ion-doped phosphors for near-infrared (NIR) luminescence in recent years. Here, trivalent chromium-doped NIR emitting SrGa2Si2O8 phosphors were synthesized. The electronic structure was calculated via density functional theory. Although only [SrO7], [SiO4], and [GaO4] polyhedra were found in the host, we still observe broadband luminescence of Cr3+ in the region of 650–950 nm from octahedra site. Due to the doping of Cr3+, a transformation from [GaO4] tetrahedron rearrange into [CrO6] octahedron was produced. The experimental results of X-ray photoelectron spectroscopy and electron paramagnetic resonance spectroscopy demonstrated the presence of Cr3+. A systematic study of the photoluminescence properties of SrGa2Si2O8:Cr3+ was conducted. The luminescent intensity of SrGa2Si2O8:0.005Cr3+ at 420 K can be retained at 83.42% compared to 300 K, indicating its high thermal stability. The electroluminescence of the prepared light emitting diode (LED) based on SrGa2Si2O8:Cr3+ and blue LED chip was measured under various currents. The application as a NIR LED light source was demonstrated in human hands.