High performance Y4Al2O9:Eu3+ phosphors: Optical, thermal, and functional applications in w-LEDs, anti-counterfeiting and advanced forensics

Abstract

In this study, un-doped and 1–5 mol % Eu³⁺ doped Y₄Al₂O₉ (YAM:Eu³⁺) phosphors are synthesized via an eco-friendly sol-gel combustion method and systematically characterized for their potential applications in white light-emitting diodes (w-LEDs), anticounterfeiting, and latent fingerprints (LFPs) detection. XRD confirmed a single-phase monoclinic structure with a P2₁/c space group, and photoluminescence studies revealed a dominant red emission peak at 611 nm (⁵D₀→⁷F₂ transition) under 392 nm excitation. YAM:3Eu³⁺ phosphors exhibited exceptional thermal stability, retaining 90.56 % of their initial luminescence intensity at 420 K, with a high activation energy of 0.41 eV. The phosphors achieved a high internal quantum efficiency (I_QE) of 92.36 % and an excellent color purity (CP) of 99.4 %. When incorporated into a WLED, the phosphors demonstrated outstanding performance with CIE coordinates (0.336, 0.340), a correlated color temperature (CCT) of 5284 K, and a color rendering index (CRI) of 96, surpassing commercial counterparts, reveals that the YAM:3Eu³⁺ phosphors is highly useful for the fabrication of w-LED and display device applications. Further, the optimized phosphor is tested (under UV light of 365 nm) for the visualization of LFP and security ink on various material surfaces. YAM:3Eu³⁺ phosphors enabled high-resolution LFPs visualization with distinct Level I–III details, including ridgeoscopic features and pore characteristics, on diverse substrates. The results demonstrated that it provides an effective method for visualizing ridge patterns, offering a promising approach for applications in these areas. For anticounterfeiting applications, YAM:3Eu³⁺ phosphor-based ink exhibited strong red fluorescence under 365 nm UV light, invisible under daylight. It demonstrated excellent stability under pH variation, UV exposure, and long-term storage. These findings establish YAM:3Eu³⁺ phosphors as a multifunctional material with superior optical properties, robust thermal stability, and high applicability in advanced lighting, forensic science, and security technologies. In conclusion, YAM:3Eu³⁺ phosphors is a very promising light-emitting material for w-LED devices, w-LEDs, anti-counterfeiting (AC) and advanced forensics.