Effect of temperature of annealing on optical, structural and electrochromic properties of sol–gel dip coated molybdenum oxide films

Abstract

The sol–gel dip-coating method is used for the preparation of MoO 3 thin films. The 6 layered MoO 3 films were prepared and annealed at various temperatures in the range of 200–350 °C. The band gap value for MoO 3 films were calculated from optical absorption measurements and it is in the range of 3.55–3.73 eV. XRD spectrum reveals (0 2 0) is the major diffraction plane for the films prepared above 250 °C, which reveals the formation of MoO 3 in α-orthorhombic phase. The films prepared at 200 °C and 250 °C exhibits amorphous nature. The FTIR spectrum confirms the presence of Mo–O–Mo and Mo O bonds. Nanorods were observed in the SEM images in the case of MoO 3 films prepared above 250 °C. The films prepared at 250 °C exhibit maximum anodic diffusion coefficient of 9.61 × 10 −11 cm 2/s. The same film exhibits the change in optical transmission of 58.4% at 630 nm with the optical density of 0.80.