Experimental and ab initio study of the structural and optical properties of ZnO coatings: Performance of the DFT plus U approach

In this work, ZnO coatings were produced by the spray-pyrolysis technique and characterized by scanning electron microscopy, X-ray diffraction and optical transmittance spectroscopy. The experimental results were compared to predictions obtained from electronic-structure calculations based on the Density Functional Theory plus U (DFT+U) approach. TO this purpose, the 2H, 4H and 6H polytspes of ZnO were theoretically analysed, and DFT+U was assessed for the calculation of structural, electronic and optical properties of the hexagonal ZnO structures. We found that DFT+U is an effective and accurate method that combined with experimental measurements, allows a deeper insight about the coatings of the wurtzite (2H) phase,synthesized in the laboratory. This comprehensive study of the pure ZnO is the fast step towards the study of complex ZnO-based coatings.