Tuning Visible-to-Near Infrared Dual-Band Emission in ZnO@β-SiC Composite Phosphor

Interface engineering is crucial for advancing the desired performances of light-emitting devices by precise control over the charge carrier recombination process. However, solid-state lighting technology depends heavily on rare-earth (RE) element-based phosphors. Since most of these materials are costly, toxic, and, as the name suggests, scarce in nature, modern science and technology are focusing on the development of artificially engineered RE-free phosphor materials. Here, solid-state reaction processed ZnO@β-SiC composites are shown to be promising phosphors, where the optimized sample gives a remarkable dual band photoluminescence (PL) in the visible to near-infrared (NIR) region after annealing at 900 °C and above. This intriguing PL behavior is intensified at low temperatures down to 20 K, whereas the visible band is red-shifted with increasing excitation wavelength. The NIR band does not shift with excitation wavelength though. However, its lifetime is measured to be 13.24 ms, which is ∼7.5 times longer than that of the visible one. All these phenomena have been discussed in light of an interplay between optically active defect centers at the ZnO/β-SiC interface and the quantum confinement effect in β-SiC nanocrystals. The tunable dual band emission in the ZnO@β-SiC composite is promising for various optical application.