High-Output-Power Broadband Near-Infrared Phosphor Suitable for Various LED Applications

The preparation of broadband near-infrared phosphors has emerged as a frontier research area, presenting significant scientific importance alongside considerable technical challenges. Cr3+-doped garnet-type near-infrared phosphors have garnered widespread attention due to their ability to be excited by inexpensive blue chips. However, existing phosphors suffer from drawbacks such as narrow full width at half-maximum and short emission wavelengths. This study employs a high-temperature solid-state method to synthesize a garnet-type phosphor, La3In2Ga3O12:Cr3+. XRD patterns confirm that the sample exhibits a garnet structure with the space group Ia3¯d. Excited at 490 nm, this phosphor exhibits strong emission within the 700–1000 nm range, with an emission peak at 826 nm and full width at half-maximum of 149 nm. This study employed a fluxing agent strategy to enhance crystallinity, thereby improving the phosphor in luminescence and ultimately identifying H3BO3 as the optimal fluxing agent. Monitoring the luminescence intensity at various temperatures revealed that at 423 K, the intensity remained at 50% of the initial value, yielding an activation energy of 0.340 eV. Finally, by fabricating the phosphor with a blue 485 nm LED chip into a near-infrared LED device, a luminous efficiency of 9.72%@20 mA was achieved, with an output power reaching 978 mW@320 mA. This device demonstrates promising applications in night vision security screening, information recognition, and biological imaging.