CaLaLiTeO6: Mn⁴⁺, Tm³⁺ phosphors with multiband near-infrared emission towards multifunctional applications

Near-infrared phosphors have garnered considerable interest for various detection technologies. However, effective blue light excitable phosphors emitting in the NIR range are still lacking in these devices. In this work, we synthesized a monoclinic perovskite phosphor, CaLaLiTeO6: Mn4+, Tm3+, which emits NIR light at 700 nm, 800 nm and 1450 nm under 480 nm excitation. Through systematic study of the fluorescence lifetime of doped Mn4+ ions, we determined this arises from energy transfer from Mn to Tm, enhancing Tm luminescence at 800 nm and 1450 nm. The measured internal quantum efficiency (IQE) of the phosphors can reach 66.36 %. Additionally, photoluminescence properties were examined under 808 nm laser diode excitation. Finally, we utilized a 480 nm blue light chip to excite the CaLaLiTeO6: 0.6 % Mn4+, 1.5 % Tm3+ phosphor and verified its functionality as a NIR light source. Results indicate phosphor-converted LEDs based on this material can be successfully used in a variety of disciplines, including medical infrared thermal imaging, enhanced night vision, solution concentration analysis. This information serves as a crucial reference for developing multifunctional phosphors.