Nanoscale Y2SrZnO5:Eu3+ luminescent inks: enhancing security and stability via triple excitation for advanced anti-counterfeiting measures

Abstract

Counterfeiting of classified documents and currency demands innovative materials to enhance their security. Here, we report a novel Eu³⁺-doped Y₂SrZnO₅ (YSZO) nanopowder, synthesized via an optimized sol–gel combustion method, and its application as a stable, luminescent ink. This oxide-based phosphor exhibits exceptional photostability under 254 nm UV light, thermal resilience up to 120 °C, and resistance to solvents and humidity, making it a robust anticounterfeiting candidate. YSZO:Eu³⁺ displays intense red emission (550–750 nm) from ⁵D₀ → ⁷F_J (J = 0–3) transitions, achieving 99.8% color purity. Security labels printed with this ink remain invisible under daylight but reveal encrypted patterns under UV (254 nm), near-UV (393 nm), and blue (465 nm) light. Its multi-environment stability ensures durable luminescence, critical for tamper-proof authentication. Unlike traditional inks reliant on toxic solvents, this non-toxic YSZO:Eu³⁺ system offers a sustainable alternative with high contrast and selectivity. These properties position Eu³⁺-doped YSZO as a breakthrough in materials chemistry, enabling reliable, counterfeit-resistant features for secure documents and currency.