Bandgap Tuning of ZrO2-SnO2 Nanocomposite thin Films by Sol-gel Dip Coating Technique

Transparent nanocomposite ZrO2-SnO2 thin films with molar ratio of ZrO2/SnO2, 0.1/0.3(ZS13), 0.1/0.2(ZS12), 0.2/0.1(ZS21), and 0.3/0.1 (ZS31) were prepared by sol-gel dip coating technique. X-ray diffraction spectra (XRD) of all samples showed the presence of either tetragonal ZrO2 or tetragonal SnO2 along with orthorhombic ZrSnO4 with variation in concentration. The grain size of ZrSnO4 was greater than that of ZrO2 or SnO2. An average transmittance greater than 75% in UV–visible region was observed for all the films. The band gap of the films increased from 4.79 - 5.30 eV and the conductivity increased in the range of 0.07x10-4-3.1x10-4 Ω-1m-1, with variations in concentration. Such ZrO2-SnO2 nanocomposite thin films can be used in solar cell and gas sensing applications.