Broadband and High Efficiency Near‐Infrared Emission in Cr³⁺‐Doped ZnWO₄ Phosphors for Spectroscopic Applications

The increasing demand for near‐infrared phosphor‐converted LEDs (NIR pc‐LEDs) has spurred extensive research on broadband NIR phosphors. A series of Cr 3+ ‐doped ZnWO 4 phosphors exhibiting broadband NIR emission was synthesized via a high‐temperature solid‐phase method. The photoluminescence (PL) excitation (PLE) spectrum of ZnWO 4 : Cr 3+ exhibits two absorption bands in the 200–400 nm and 400–600 nm ranges, which match well with near‐ultraviolet and blue LED chips. Under excitation, the PL spectrum shows a broad NIR emission extending from 700 to 1400 nm, with a full width at half maximum (FWHM) of approximately 210 nm. The internal quantum efficiency (IQE) was measured to be 55.36%. At 373 K, the integrated emission intensity of ZnWO 4 : 0.05Cr 3+ is about 47.5% of that at room temperature (RT). Additionally, a prototype NIR pc‐LED device was fabricated by embedding the ZnWO 4 : 0.05Cr 3+ phosphor into a silicone matrix and coupling it with a 450‐nm blue LED chip. The device delivered an output power of 17.12 mW at a 140‐mA driving current and a photoelectric conversion efficiency of 14.42% at 20 mA. These results demonstrate the promising potential of this NIR pc‐LED for practical applications such as night vision and vein imaging.