Highly Efficient Broadband NIR Phosphor Ca3ZrNbGa3O12: Cr3+, Yb3+ in pc‐LED Applications

ABSTRACT The development of biomedicine, military and other fields has led to an increasing demand for near‐infrared light sources, and near‐infrared phosphorescent conversion light‐emitting diodes (NIR pc‐LED) occupy a critical position in these fields. However, the problems of weak luminescence intensity and poor thermal stability have generally been exhibited by the near‐infrared fluorescent materials reported to date. This article synthesized a series of Ca 3 ZrNbGa 3 O 12 : Cr 3+ phosphors by the high‐temperature solid‐phase method. Under 342 nm excitation, the phosphors produced emission light covering the wavelength range of 650–1150 nm. The luminescence center was 783 nm, corresponding to the 4 T 2 → 4 A 2 transition of Cr 3+ , and the full width at half maximum (FWHM) was 129 nm. Subsequently, with the continuous introduction of Yb 3+ into the system, the 2 F 5/2 → 2 F 7/2 transition of Yb 3+ generates multiple luminescent centers in the near‐infrared region, thereby broadening the spectral coverage range. The incorporation of Yb 3+ ions enables efficient energy transfer from Cr 3+ to Yb 3+ in the system. When the concentration of Yb 3+ is 8%, the energy transfer efficiency reaches 64.1%. The Photoluminescence quantum yield (PLQY) was also improved from 41.4% of Ca 3 ZrNbGa 3 O 12 : 0.7% Cr 3+ to 69.3% of Ca 3 ZrNbGa 3 O 12 : 0.7% Cr 3+ , 0.6% Yb 3+ . The thermal stability at 150°C was also improved from 36.06% to 43.06%. A near‐infrared pc‐LED device was fabricated through the integration of Ca 3 ZrNbGa 3 O 12 : 0.7% Cr 3+ , 0.6% Yb 3+ phosphor with a 365 nm LED chip, thereby validating the material's potential for application as a novel near‐infrared illumination source.