Effect of molarity on sol-gel routed nano TiO2 thin films

Abstract

The nanostructured titanium dioxide (TiO2) thin films have been prepared for the molar concentrations of titanium tetra isopropoxide (TTIP) 0.05 M, 0.1 M, 0.15M and 0.2M by sol-gel routed spin coating technique with calcination at 450°C. The processing parameters such as, pH value (8), catalyst HCl (0.1 ml), spin speed (3000 rpm) and calcination temperature (450°C) are optimized. The crystalline nature and surface morphology were analyzed by XRD, SEM and AFM analysis. The XRD results confirm that the films are crystalline with anatase phase, and are nanostructured. The SEM micrographs of the TiO2 film reveal the spherical nature of the particle. AFM analysis establishes that the uniformity of the TiO2 thin film was optimized at 0.2 M. The optical measurements show that the transmittance depends on the molarity, and the optical band gap energy of TiO2 films is found to be inversely proportional to molarity. The I-V characteristics exhibit that the molarity strongly influences the electrical conductivity of the film. The results indicate that the significant effect of molarity on structural, optical and electrical properties of the nanostructured TiO2 thin films will be useful to photovoltaic application.