Li/Na substitution and Yb3+ co-doping enabling tunable near-infrared emission in LiIn2SbO6:Cr3+ phosphors for light-emitting diodes

Near-infrared (NIR) phosphor-converted light-emitting diode (pc-LED) has great potential in non-invasive detection, while the discovery of tunable broadband NIR phosphor still remains a challenge. Here, we report that Cr3+-activated LiIn2SbO6 exhibits a broad emission band ranging from 780 to 1400 nm with a full width at half maximum (FWHM) of 225 nm upon 492 nm excitation. The emission peaks are tuned from 970 to 1020 nm together with considerable broadening of FWHM (similar to 285 nm) via Li/Na substitution. Depending on Yb3+ co-doping, a stronger NIR fluorescence peak of Yb3+ appears with improved thermal resistance, which is ascribed to efficient energy transfer from Cr3+ to Yb3+. An NIR pc-LED package has been finally designed and demonstrated a remarkable ability to penetrate pork tissues (similar to 2 cm) so that the insertion depth of a needle can be observed, indicating that the phosphor can be applied in non-destructive monitoring.

Automated summary

Cr3+-activated LiIn2SbO6 exhibits a broad emission band from 780 to 1400 nm upon 492 nm excitation, which can be tuned by Li/Na substitution and shows stronger NIR fluorescence peak with Yb3+ co-doping. The designed NIR pc-LED package has the ability to penetrate pork tissues and monitor the insertion depth of a needle, indicating potential application in non-destructive monitoring.