Dye-sensitized solar cells based on nanocrystalline TiO2 and natural pigments

We report the fabrication of solar cells based on nanocrystalline TiO2 sensitized with anthocyanins extracted from various plants, such as red cabbage and red onion, in an attempt to recycle residues from the food industry. We vary the solvent and the conditions in which the dye is extracted and analyze their effect on the solar cell performance. We find that all the extracts present light harvesting properties and perform charge transfer sensitization of the TiO2 semiconducting layer. The current-voltage curves have the expected shape for a photovoltaic device and the values of the fill-factors are relatively good, some in excess of 0.57. The efficiency, measured under standard AM 1.5 conditions, is 0.17 or lower, which is typical for most natural extracts tested so far.