An efficient strategy of charge compensation for Ni2+-activated SrTiO3 perovskite near-infrared phosphor toward optical imaging illumination

Near-infrared (NIR) light sources have great potential in applications such as optical imaging, non-destructive medical diagnosis, and non-visual lighting. Ni2+ activated phosphors as a class of newly discovered NIR emitting material shows broadband luminescent properties that covers NIR-II (1000–1600 nm) region which is relatively transparent and less scattering in tissues. However, it has shortcomings, such as low luminous efficiency and poor thermal stability that need to be improved. Here, we report the synthesis of new Ni2+-activated SrTiO3 perovskite-based broadband NIR phosphor by high-temperature solid-state reaction method, with M5+ (M = Ta, Sb, Nb, P) as the co-doping agent to compensate charges. By charge compensation, the new composition significantly improved the NIR emission intensity by 12 folds, increased the luminescence quantum efficiency from 7.9% to 19.7%, and improved the resistance to thermal quenching. We studied the synergistic effect of charge compensation on the luminescence performance of NIR phosphor by experimental and simulation approaches. We showed that co-doping of charge compensator improved NIR phosphors by eliminating electronic defects and introducing defect or distortion to lattice octahedra. We further demonstrate that NIR pc-LED can be made by packaging the optimized NIR phosphor with a UV LED chip. Its potential application in the field of optical imaging was discussed.