PVP-driven surface engineering of Ce³⁺ doped Dy₂O₃ nanoparticles for dual mode thermo and photoluminescence in forensic, anti-counterfeit, and solid-state lighting applications

Abstract

Dysprosium oxide (Dy₂O₃) nanoparticles doped with cerium ions (Ce³⁺, 1–9 mol%) were synthesized using a solution combustion approach and functionalized with polyvinylpyrrolidone (PVP, 9 wt%) to enhance surface stability and optical response. X-ray diffraction analysis confirmed a pure cubic phase with decreasing crystallite size (~20 to ~12 nm) as Ce³⁺ content increased. Infrared spectroscopy and high-resolution electron microscopy revealed effective surface coordination between metal oxygen bonds and the PVP matrix, leading to uniform particle dispersion and the formation of shell. Optical measurements showed a progressive widening of the band gap (4.85–5.09 eV), attributed to both surface passivation and size-induced quantum effects. Photoluminescence studies revealed distinct emission peaks at 476 nm (blue), 578 nm (yellow), and 663 nm (red), with maximum intensity at 9 mol% Ce³⁺, indicating efficient Ce³⁺→Dy³⁺ energy transfer and suppression of non-radiative pathways. The optimized composition exhibited a high photoluminescent quantum yield of 86.12 ± 2.5% and a fast decay time of 6.1 ns. Chromaticity analysis yielded a correlated color temperature of 6644 K and a color rendering index of 97, suitable for warm white lighting. Additionally, thermoluminescence measurements revealed a stable glow peak near 325 °C with an activation energy of 1.17 eV, demonstrating applicability in high-dose radiation sensing. The nanomaterial also displayed strong fluorescence under UV illumination, enabling effective visualization of latent fingerprints and anti-counterfeiting features. These results highlight the multifunctional capabilities of Ce³⁺-modified Dy₂O₃ nanoparticles engineered through PVP-assisted surface modification, positioning them as promising candidates for advanced photonic, security, and sensor technologies.