We report on ZnO films doped with different Co concentrations (0, 0.5, and 1 wt%) prepared by sol-gel technique in association with dip-coating onto glass substrates. Zinc acetate dehydrate, cobalt acetate, mono ethanolamine were used as starting materials, as well as solvent and stabilizer, respectively. Nanostructured polycrystalline ZnO thin films with different concentrations of Co doping (0, 0.5, and 1 wt%) are prepared for the first time by the sol-gel method and annealed at 500• C for 1 h. The surface morphologies of the ZnO thin films deposited on glass substrate with different concentrations were evaluated by atomic force microscopy. The optical absorption of the films showed a blue shift of the band gap. The photoluminescence signal of the thin films of undoped and Co-doped ZnO presents different bands in the visible region. The electrical conductivity of the sample with 0.5%Co was found to be 4.62 (Ω C m) −1 .

Undoped and Ag-doped ZnO thin films with different silver concentrations (0, 1, 3, and 7 wt%) were synthesized by sol-gel method and deposited onto glass substrate by dip-coating technique. Zinc acetate dehydrate and silver nitrate were used as starting materials. 2-Methoxyethanol and ethanolamine were used as solvent and stabilizer. Characterization by X-ray diffraction has revealed that the undoped and Ag-doped ZnO are polycrystalline, and have the wurtzite hexagonal structure with a preferred orientation along c-axis. The nanometric size (27-34 nm) of ZnO crystallites varies with the concentration of Ag. The surface morphology analysis, by atomic force microscopy and scanning electron microscopy, depicts a homogeneous dispersion of ZnO crystallites in the form of randomly spread wrinkles-like formation. The Raman spectroscopy confirms the Ag incorporation in the ZnO lattice. All films exhibit a transmittance greater than 75% in the visible region, and a sharp absorption band at 325 nm corresponding to the fundamental absorption edge. The room-temperature photoluminescence spectra of the prepared thin films display a strong ultraviolet band at 380 nm originated from excitons recombination, and four bands in the visible region at 430 nm (violet), 460 nm, 480 nm (blue) and 530 nm (green) from created defect levels in the band gap. These synthesized materials may be potential candidates in the manufacture of devices using short wavelengths.

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