Novel high-efficiency near-infrared phosphor CaZrTaGaO7:Cr3+ and its application in night vision and anti-counterfeiting†

Near-infrared (NIR) light attracts attention because of its promising applications in night vision, anti-counterfeiting, biosensors, and measuring food composition and freshness. However, new NIR light sources with excellent thermal stability, higher efficiency, and superior photoelectric conversion efficiency are still a significant challenge. In this study, CaZrTaGaO₇:0.01Cr³⁺, which can convert visible light into NIR light, was synthesized using a high-temperature solid-state method, and the crystal structure, morphology, site preference, and luminescence properties were investigated. Under 460 nm blue light excitation, the phosphor produces a broadband NIR emission in the 600–1100 nm region (λ_max = 829 nm), with a full width at half maximum of 178 nm, an internal quantum efficiency of 90.7%, and an excellent thermal stability of 84.8% at 423 K. A NIR light emitting diode (LED) was prepared using a 460 nm LED chip and CaZrTaGaO₇:0.01Cr³⁺, and the new compound can produce strong NIR emission (273 mW at 100 mA) with a photoelectric conversion efficiency of 11.8%. Photographed phosphor-converted LEDs (pc-LEDs) with a regular camera and captured pc-LEDs in operation in the dark. The results indicate that this material may provide a new option for high power NIR night vision and other applications.