Optical properties of ZnO:SiO₂:Tb³⁺ films: the effect of DNA

Abstract Thin films of zinc oxide and those doped with terbium (at concentrations of 0.1–5.0 mol%) were synthesized on glass substrates using the sol–gel method. The UV–Vis transmission spectra showed that transparency increases from 60% to 86% with an increase of Tb content. All terbium-doped samples exhibit a rise in Eg from 3.37 eV for zinc oxide to 3.827 eV for doped films. The photoluminescence (PL) of zinc oxide doped with terbium in the UV (260 nm) region and the fluorescence of terbium in the visible region (330 nm) were studied. The intensity of green luminescence with an increase in the amount of terbium increases by an average of 6%. The yield of green fluorescence relative to PL also goes up with an increase in the concentration of terbium concentration of terbium from 5% to 7.4%. DNA deposited on the surface of the plate extinguishes PL by an average of 5.5% and has a weak effect (<3%) on terbium fluorescence in the visible region. SEM images without DNA consist of spherical structures—0.5–2.0 μm in diameter, assembled in the form of pentagons. The presence of DNA on the surface is expressed as ‘stars’ of white color of regular and irregular shapes, located on the surface inside these pentagons.