The sol-gel TiO2/purified natural clay electrodes having Ti:Si molar ratios of 95:5 and 90:10 were initially prepared, sensitized with natural red cabbage dye, and compared to the sol-gel TiO2 electrode in terms of physicochemical characteristics and solar cell efficiency. The results showed that the increase in purified Na-bentonite content greatly increased the specific surface area and total pore volume of the prepared sol-gel TiO2/purified Na-bentonite composites because the clay platelets prevented TiO2 particle agglomeration. The sol-gel TiO2/5 mol% Si purified Na-bentonite and sol-gel TiO2/10 mol% Si purified Na-bentonite composites could increase the film thickness of solar cells without cracking when they were coated as a scattering layer on the TiO2 semiconductor-based film, leading to increasing the efficiency of the natural dye-sensitized solar cells in this work. (C) 2011 Elsevier Ltd. All rights reserved.