Amorphous CeO2 thin films were deposited by a dip-coating method on Corning glass substrates and annealed for one hour at the temperatures (T) of 250, 450, and 550°C in air for crystallization. The precursor solution was prepared by dissolving cerium acetate in methanol, lactic acid, glycerol, and trimethylamine at 55°C. X-ray diffraction (XRD) patterns showed the cubic structure of CeO2. From XRD data and employing the Scherrer formula, the crystallite size (CS) was calculated to be within the 4.0±0.5 to 10±1 nm interval. SEM micrographs revealed cracks of the films annealed at 250 and 450°C, even though for 550°C, the film shows a homogeneous morphology free of cracks. CS increases (from 4.0 to 10 nm) and thickness decreases (from 217 to 182 nm) when T increases. The UV-vis spectra exhibited an average transmittance of 80% in the 300 to 2000 nm wavelength range. Also, from XRD, it was observed that the lattice shrinks and from transmittance that the bandgap energy increases with T. The Raman spectra exhibit 461 cm-1 assigned to F2g mode of the fluorite cubic structure, where F2g hardens when T increases as an effect of the shrinkage of the lattice.

Zirconium oxide (ZrO2) thin films were prepared by the sol-gel dip coating technique, in combination with annealing at different temperatures in air atmosphere, with the final goal of studying the water wettability of the surface. The annealing effects on the structural and optical properties of the ZrO2 films were investigated to check the characteristics of the material. X-ray diffraction (XRD) patterns of ZrO2 annealed at 450 °C and 550 °C show the formation of tetragonal phase, with layers constituted by nanoparticles with average particle size of 21 nm and 25 nm, respectively. Fourier-transform infrared spectroscopy (FT-IR) spectra revealed the presence of vibrational modes associated to ZrO2. Photoluminescence (PL) and ultraviolet-visible spectroscopy (UV–Vis) spectroscopy was used for optical properties. All deposited ZrO2 thin films presented a high optical transparency, with an average transmittance above 70% in the visible range (400–700 nm). The hydrophilic properties of ZrO2 films were characterized by means of the measurements of the contact angle. When the sample was annealed at 550 °C, the hydrophilicity reached the best behavior, which was explained as an effect of the structural and morphological change of the films.

The present study reports the synthesis of colloidal Cu2ZnSnS4(CZTS) nanocrystals (average size ~4–9 nm) by a simple and low cost hot-injection method. These nanocrystals form larger particles with sizes around 40 nm. Oleylamine (OLA) was used as both the solvent and the nanocrystal stabilizer. The effect of the synthesis time on the structural, compositional, morphological, and optical properties was studied. As revealed by XRD, Raman, and TEM measurements all the prepared samples are comprised of both kesterite and wurtzite CZTS nanocrystals. The wurtzite phase contribution reduces as the reaction time is increased. The “bandgap” of the obtained nanoparticles tends to 1.52 eV for the larger synthesis times (24 h) which is suitable for an absorber layer in thin films solar cells.