Enhanced Short-Wave Infrared Luminescence in Yb³⁺-Doped Cr(PO₃)₃ Phosphor with over 60% External Quantum Efficiency

Short-wave infrared (SWIR) light sources, as crucial components of SWIR imaging and spectroscopy technologies, have garnered significant attention recently. The rapid development of portable electronic devices has created a demand for compact and efficient SWIR emitters, and phosphor-converted SWIR LEDs represent the optimal technological solution to meet this requirement. Here, a Cr(PO₃)₃:Yb³⁺ phosphor with highly efficient and pure SWIR luminescence under 450 nm blue LED excitation is reported. Upon doping with Yb³⁺ in the Cr(PO₃)₃ matrix, the resulting material is capable of effectively converting blue excitation photons to SWIR luminescence spanning from 900 to 1200 nm, with a dominant emission peak at 1003 nm due to the efficient energy transfer from Cr³⁺ to Yb³⁺. Notably, this phosphor demonstrates an ultrahigh internal quantum efficiency (IQE) of 95.7% and a record external quantum efficiency (EQE) of 60.3% upon 450 nm blue light excitation. Moreover, the fabricated SWIR LED prototype device by combining the Cr(PO₃)₃:Yb³⁺ phosphor and a commercial 450 nm blue LED chip exhibits SWIR output power of 24.1 mW at 200 mA input current and a photoelectric conversion efficiency of 12.8% at 20 mA. This study not only opens avenues for realizing high-efficiency SWIR luminescence by deliberately controlling energy transfer pathways in Cr-based material systems but also paves the way for the development of high-power SWIR light sources.