Investigation of the effect of sol processing parameters on the photoelectrical properties of dye-sensitized TiO2 solar cells

Abstract

Sol-gel spin-coating method has been explored to prepare nano-crystalline TiO2 films for dye-sensitized TiO2 solar cell application. Effects of evaporation temperature at which the sol is concentrated and addition of polyethelene glycol (PEG) to the sol at different concentrations on film thickness, surface morphology and solar cell performance are studied. Conversion efficiency is found to increase with PEG addition up to 40 % by weight of TiO2 and then decrease with further addition due to the development of cracks in the films. Higher conversion efficiency has been obtained with the sol concentrated at 40°C than at room temperature (30°C) after which it is found to decrease with increase in temperature due to higher degree of agglomeration caused by faster rate of evaporation. Further, it is observed that though the photocurrent and efficiency gradually increase with thickness at relatively lower thicknesses, a saturation in the photocurrent occurs at higher thicknesses.