Dye-sensitized solar cells (DSSCs) which are also called Graetzel cells are novel type of solar cells. The technology and devices proposed relates to a photo-electrochemical solar cell comprising a photoanode made of a semiconductor-based nanocrystalline film with a natural pigments as photosensitizer (i.e. anthocyanin and/or betalain dye or an engineered mixture of both) adsorbed on it and deposited on a transparent and conductive support. A wide band gap semiconductor like TiO2 is used for charge separation and transport. The cathode, besides the conventional ones, can be constructed by glass or metal, such as ceramic, bricks, tiles, wood, and fabrics, all suitably made conductive and coated with catalyst.
The dye extraction methods, the choice of the right mixtures of natural pigments have been characterized and studied in order to reach stability and electrical efficiency comparable with dyes based on metal complexes.
The Bio-photovoltaics cell proposed provides reasonable light harvesting efficiency, sustainability, low cost and easy waste management. Its main advantages are mainly low cost production, flexibility, performance also at diffuse light and multicolor options.
The cell could be integrated into large varieties of products, e.g. hand bags or clothing, indoor applications, and building-integrated photovoltaics such as roll-able devices for walls of buildings or windows. But components of a DSSC should be optimized for the suitable applications.
The photoelectric performances of the natural DSSCs sensitized cells have been compared to a standard artificial dye based on a Ruthenium dicarboxylic polypyridine complex (referred to as the artificial complex N3) under similar conditions. The results achieved shows that our natural cells present an efficiency of 70% with respect to the artificial one (i.e 1.5%).
Solar cells are devices designed to convert solar energy into electricity. In particular the photo-electrochemical cells, named as third-generation solar cells, offer the possibility to move from the dependence of silicon and, thanks to the use of natural dyes and other cheap components, makes them a more economical viable strategy with respect to first generation solar cells (Silicon-based). The possible application spans from the integration of the cell into in floor or wall tiles, furniture, toys, cars, railway carriages, clothes and garments in general, sails, tents, beach umbrellas, etc.
Moreover, since the bio-photovoltaic cell is composed by natural pigments and material that present an easy and safety waste management, the technology can be exploited in the educational market by building kits for the dissemination of renewable energy culture.
Giulio Bollino
