Multifunctional Eu3+-activated phosphors with single-band ratiometric thermometry and hidden anti-counterfeiting functions

Developing phosphors with high luminescence efficiency and multifunctional capabilities remains a key challenge for advanced optical applications. Here, we report a red-emitting CaLaLiTeO 6 :Eu 3+ (CLLT:Eu 3+ ) phosphor that exhibits bright and stable 5 D 0 → 7 F J emission, with a peak at 615 nm and color purity up to 99.9 %. Structural and optical analyses confirm that Eu 3+ ions occupy La 3+ sites without disrupting the host lattice. Notably, the phosphor demonstrates distinct temperature-dependent excitation behaviors, enabling single-band ratiometric (SBR) temperature sensing through dual-excitation modulation. The optimized CLLT:15 %Eu 3+ sample achieves high PLQY (62.25 %) and maintains strong emission under elevated temperatures, while the FIR-based SBR models exhibit excellent relative and absolute sensitivities. The strong red emission of CLLT:Eu 3+ further enables applications in plant-growth lighting, anti-counterfeiting, and fingerprint display, demonstrating the versatile functionality of the phosphor. This work provides a feasible strategy to integrate luminescence performance, temperature responsiveness, and multifunctionality in a single phosphor system.