Dear Mahsa Amiri ;

TiO2 thin films can be prepared by sol-gel process using titanium isopropoxide (Aldrich, 98%) at room temperature for 1 h. The precursor of titania mixed with isopropyl alcohol and hydrochloric acid in stoichiometric amounts. The films were prepared using solutions with 2 < pH < 4 and atmosphere relative humidity

Spin coating can give you better control in terms of thickness...if you optimise gel nd rpm, time for spin nd all...but as centrifugal force is working...suspension of add particle should be proper so uniformity can be achieved.

There is a growing awareness that titania (TiO2) and TiO2-based oxide systems are the most promising candidates for the development of photoelectrodes for photoelectrochemical cell (PEC) for solar-hydrogen production [1]. The PEC is equipped with a single photoelectrode (photoanode) and cathode, both of which are immersed in an aqueous electrolyte. In this work we present a sol-gel method to prepare TiO2 thin films on ITO using tetraisopropoxides of titanium, acetylacetone, 1-butanol and Tween 80 as surfactant. The films were deposited on ITO coated glass slides by spray pyrolysis. UV-VIS spectra and fluorescence measurements were made for the solutions and films. X-ray diffraction was used for structural investigations and the morphology of the film was studied by Scanning Electron Microscopy.

Mahsa Amiri you can refer following paper for deposition of TiO2 thin film using spin coating method.

Dip coating and spin coating have there different working principles. as personally I using spin coating method so here I would like to recommend spin coating method, working principle and advantages of these both methods can find in attached link https://www.ossila.com/pages/dip-coating, https://www.ossila.com/products/spin-coater.

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