Rapid expansion of TiO2 layers processed by supercritical solutions for dye sensitized solar cell applications

In this work, anatase-type TiO2 layers were prepared by deposition of precursor solution including titanium isopropoxide, ethanol and acetic acetylacetone on a FTO substrate using rapid expansion of supercritical solutions (RESS). The spraying to obtain a particulate coating of TiO2 was carried out at 65 degrees C and 180 bar of supercritical carbon dioxide environment. Then, thermal annealing at 550 degrees C for 2 h was applied to coated substrates to obtain desired phase composition. The structural and optical properties of the film were evaluated by XRD, SEM and UV-Vis. SEM observation showed that the photoanode film has porous microstructure with interconnected spherical TiO2 grains. TiO2 film has a band gap of 2.6 eV.