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

The sol-gel dip-coating method is used for the preparation of MoO3 thin films. The 6 layered MoO3 films were prepared and annealed at various temperatures in the range of 200-350 °C. The band gap value for MoO3 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 MoO3 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 MoO bonds. Nanorods were observed in the SEM images in the case of MoO3 films prepared above 250 °C. The films prepared at 250 °C exhibit maximum anodic diffusion coefficient of 9.61 × 10−11 cm2/s. The same film exhibits the change in optical transmission of 58.4% at 630 nm with the optical density of 0.80.