Optical characterization of nanostructured MnO2ZnO thin films prepared from acetate-based sol−gel precursors

In the present work, the MnO2ZnO thin films were prepared by sol–gel dip-coating method on glass substrates. The effects of zinc concentration with 8, 16 and 25% molar ratios of Zn(ac) to Mn(ac) on structural, morphological and optical properties of thin films were characterized by XRD, AFM, SEM, EDX, FTIR and UV−vis spectroscopy measurements. The results of XRD patterns showed that the MnO2ZnO thin films are amorphous for samples containing, respectively, 16 and 25% molar ratios of Zn to Mn. 3D atomic force microscopy (3D AFM) revealed that the surface roughness of thin films decreased with increasing Zn contents. The SEM images indicated that the granular surface morphology trends to a flat and smooth shape with increasing Zn content. EDX studies confirmed that the thin films contained O, Mn and Zn species. The formations of MnO and other bond were identified by FTIR. The refractive index, absorption coefficient, and optical band gap were calculated by Tauc–Lorentz model with simulating the transmittance data. The optical band gap of MnO2ZnO thin films with Zn content of 8, 16 and 25% was obtained about 1.91, 1.71, and 1.82 eV, respectively. The volume and the surface energy loss (VELF & SELF) were also determined.