Near-Infrared Luminescence of Cr<sup>3+</sup>-Doped Ba<sub>2</sub>NaNb<sub>5</sub>O<sub>15</sub> Embedded in Transparent Glass-Ceramics as Solid-State Illumination for Night-Vision Imaging
Wenbo Ji, Fengmei Zhu, Yuan Gao, Jianbei Qiu
Abstract
Near-infrared phosphor-converted light-emitting diodes (NIR pc-LEDs), a widely used NIR light source, are typically prepared by sealing the NIR phosphor powder and an LED chip with epoxy resin. One issue that NIR pc-LEDs frequently encounter is the aging and deterioration of epoxy resin over time, which leads to self-absorption and a sharp decline in emission efficiency. Here, we report the synthesis of a chemically stable NIR luminescent material composed of Cr 3+ -doped Ba 2 NaNb 5 O 15 nanocrystals measuring 10–15 nm, with Cr 3+ ions located in the octahedral centers of the nanocrystals. Under 460 nm light excitation, the transparent glass-ceramic exhibited a broadband NIR emission in the range of 600–1400 nm, which originated from the electronic transition of Cr 3+ from the excited state of 4 T 2 to the ground state of 4 A 2 . The emission peak was located at ∼810 nm, the FWHM was ∼230 nm, and the internal quantum efficiency reached ∼0.81%. We constructed a stable NIR pc-LED device using optimized transparent NIR-emitting glass-ceramics and a commercially available blue LED chip, demonstrating its promising application in night-vision lighting. Our study provides a basis for the preparation of transparent glass-ceramic-based NIR pc-LED devices as an improved alternative for solid-state illumination.