A novel red-emitting Cd₂CaTeO₆: Eu³⁺ phosphor with abnormal thermal quenching properties for personal identification...

Fingerprint and lip print detection are key biometric tools for identity verification and forensics. Current methods for latent fingerprints suffer from poor contrast, sensitivity, and toxicity, while lip print techniques like smoking or vacuum coating lack visibility and practicality. White LEDs (w-LEDs) are promising but limited by low color-rendering index (CRI) and high correlated color temperature (CCT). A newly synthesized orange-red-emitting tellurate phosphor, Cd₂CaTeO₆ (CCTO): xEu³⁺ (x = 0.05-0.30 mol), was produced through high-temperature solid-state method. Detailed analysis was conducted on the phase purity, morphology, and luminescence properties of the synthesized phosphors. Its thermal quenching temperature was higher than 480 K, and the residual intensity at 420 K was 106 % compared with the initial intensity. The w-LED prepared by CCTO: Eu³⁺ exhibited an excellent CRI of 88 while maintaining a suitable CCT of 5814 K and CIE Chromaticity were (0.326, 0.341). Their unique properties show significant potential for enhancing the performance of solid-state lighting. In addition, CCTO: Eu³⁺ readily exhibits the level I-III characteristics of fingerprints and the detailed characteristics of lip lines. Prepared phosphors are effective in identifying latent fingerprints and lip print in real scenes. It can be widely used in the field of detecting LFPs and lip prints because of its advantages of simplicity, safety, and convenience. This work demonstrates the promising potential of the CCTO: Eu³⁺ phosphors in w-LEDs and personal identification.