Exploring the potential of BaLa₂ZnO₅ doped with individual rare-earth ions (Ce³⁺, Er³⁺, Eu³⁺) for w-LEDs, latent fingerprints, and anti-counterfeiting applications

Abstract

The novel Ce³⁺/Er³⁺/Eu³⁺ (1 mol %) activated BaLa₂ZnO₅ (BLZO) nanophosphors (NPs) were synthesized via a combustion method. Micro-morphology, phase purity, luminescence characteristics, and crystallographic structure of the material are examined. The NPs with the subsequent characteristics exhibit notable emission under 349, 378, and 395 nm excitation: BLZO:Ce³⁺, BLZO:Er³⁺, and BLZO:Eu³⁺ at 400, 550, and 615 nm, respectively. The decay curves of each sample are recorded for specific excitation and emission wavelengths respectively. All the decay curves are well-fitted with single exponential function. The observed average decay time is 1.563, 1.165 and 0.949 ms. In addition, photometric studies including Chromaticity International d’Eclairage (CIE), correlated colour temperature (CCT) and colour purity (CP) are performed. The phosphor demonstrated good contrast, minimal background interference, and great resolution when applied to several substrates in latent fingerprints (LFPs). Therefore, the phosphor provides a material that shows promise for latent fingerprint visualization. The feasibility of the Anti-counterfeiting (AC) function of BLZO: Ce³⁺/Er³⁺/Eu³⁺ phosphor is investigated on a diverse of surfaces using both screen-printing and handwriting techniques. By means of aging, heat treatment, and water immersion treatment, the durability of all three security inks has been investigated. These diverse characterization results indicate that the hypothesized Ce³⁺/Er³⁺/Eu³⁺ activated BLZO phosphor has potential applications in solid-state lighting for white light emitting diodes (w-LEDs), LFPs and AC techniques.