Deposition of silica protected luminescent layers of Eu:GdVO4 nanoparticles assisted by atmospheric pressure plasma jet

• Luminescent films were obtained by spray deposition of Eu:GdVO4 nanophosphors.
• Plasma jet deposition of SiO2 fixed the nanophosphors on the substrate.
• Optical properties of nanophosphors were preserved after deposition-fixing process.
• Films well-adhered to the substrate, even after a scotch tape peeling test and a scratch test.

Eu:GdVO4 nanophosphors with an average size of 60 nm, synthesized by a facile solvothermal method, were deposited on monocrystalline silicon wafers by a spray-coating technique with artworks anti-counterfeiting applications in mind. Atmospheric pressure plasma jet (APPJ) was used to deposit a silica-based layer on top of the nanometric luminescent layer, in order to improve its adhesion to the substrate and to protect it from the environment. The nanophosphors were characterized by X-ray diffraction (XRD) and transmission electron microscopy (TEM). Coating composition was investigated by Fourier transform infrared spectroscopy (FT-IR) and its morphology was characterized by scanning electron microscopy (FEG-SEM). The film thickness was evaluated by means of ellipsometry and adhesion was estimated by a peeling test. Luminescent properties of the nanophosphors deposited and fixed on silicon wafers were also measured. The whole layer resulted well-adhered to the silicon substrate, transparent and undetectable in the presence of visible light, but easily activated by UV light source.