Effects of 1064 nm laser on the structural and optical properties of nanostructured TiO2 thin film

TiO2 thin film has been widely used as photoelectrode in dye-sensitized solar cells. It can also be used in quantum dot synthesized solar cells. Study of its effects in different spectrum of light is important for its use in solar cells. We have reported effects of 1064 nm laser on the surface morphology, structural and optical properties of nanostructured TiO2 thin film deposited on glass substrates using sol-gel spin coating technique. Q-Switched Nd:YAG pulsed laser at various power densities is used in this study. Surface morphology of the film is investigated using X-ray diffraction (XRD) and atomic force microscopy technique. The XRD pattern of as deposited TiO2 thin film is amorphous and after laser exposure it became TiO2 anatase structure. Atomic force microscopy of the crystalline TiO2 thin film shows that the grain size increases by increasing laser power density. The calculations of the band gap are carried out from UV/Visible spectroscopy measurements with JASCO spectrometer. For laser power density of 25 MW/cm2 there is an increase in the transmission and it decreases at the value of 38 MW/cm2 and band gap decreases with increasing laser power density. Photoluminescence spectra of the crystalline TiO2 thin film indicate two broad peaks in the range of 415 and 463 nm, one for band gap peak (415 nm) and other for oxygen defect during film deposition process.