Enhancing Near-Infrared Photoluminescence Intensity and Spectral Properties in Yb3+ Codoped LiScP2O7:Cr3

Near-infrared (NIR) phosphors have received increasing attention for designing novel solid-state light sources with broadband NIR output. In this work, a novel NIR phosphor LiScP2O7:Cr3+ (LSP:Cr3+) is developed with the emissions (750–1100 nm) completely in the NIR spectral range. Under 470 nm excitation, LSP:0.06Cr3+ shows broadband NIR emissions peaking at ∼880 nm, with a full width at half maximum (FWHM) of ∼170 nm and an internal quantum yield (IQY) of ∼38%. Moreover, photoluminescence (PL) improvements of LSP:Cr3+ phosphors are achieved by Yb3+ codoping, leading to the broadened FWHM (up to ∼210 nm), increased IQY (ηmax = ∼74%), and reduced thermal quenching. The energy transformation processes in LSP:Cr3+,Yb3+ are quantitatively analyzed on the basis of PL lifetime and QY measurements, revealing that the PL improvements by Yb3+ codoping principally originate from the energy transfer from Cr3+ to more efficient and thermally stable Yb3+ emitters. Finally, NIR phosphor-converted light-emitting diodes (pc-LEDs) are fabricated by combining LSP:Cr3+,Yb3+ phosphors with blue LED chips, giving a maximum NIR output power of ∼36 mW and photoelectric efficiency of ∼12% at 100 mA drive current. The results suggest that the investigated phosphors would be promising luminescent converters for broadband NIR pc-LED applications.