Broadband near-infrared double-perovskite phosphor Sr2ScTaO6:Cr3+, Yb3+ for NIR pc-LED applications

The broadband near-infrared (NIR) phosphor converted light emitting diode (NIR pc-LED) has garnered unprecedented attention due to its crucial role in NIR applications. However, there remains a scarcity of efficient broadband NIR luminescence materials capable of emitting NIR light with wavelengths greater than 800 nm. This study reports the synthesis, crystal structure and photoluminescence (PL) properties for double perovskite Sr2ScTaO6:Cr3+ phosphors which exhibit a broadband NIR emission in the 650-1250 nm range, peaking at similar to 815 nm with the full width at half maximum (FWHM) of 161 nm. The observed broadband emission arises from two distinct Cr3+ centers, namely Sc3+ and Ta5+ octahedral sites within the Sr2ScTaO6 structure, as demonstrated by luminescence and decay kinetic analysis. A significant enhancement of the thermal stability and a remarkable broadening of the FWHM (from 161 to 275 nm) are achieved by employing Yb3+ co-doping strategy. The efficient energy transfer from Cr3+ to Yb3+ was confirmed through emission and excitation spectra, as well as luminescence decay measurements. Finally, Sr2ScTaO6:Cr3+-Yb3+ phosphor was integrated with a 470 nm blue LED chip to fabricate a NIR pc-LED device, and its potential application in night vision was evaluated.