Preparation of sol–gel TiO2/purified Na-bentonite composites and their photovoltaic application for natural dye-sensitized solar cells

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.