Recent advances in hybrid solar cells based on natural dye extracts from Indian plant pigment as sensitizers

Alternate energy source has become imperative for green energy solution against ever growing demand. Hybrid solar cell is yet another promising option toward green energy providing opportunity to explore natural dye extracts from plants. This review explores recent developments in the field of hybrid solar cell technology specifically with sensitizer synthesized from plants which are also found in India. Anthocyanin, betalain, chlorophyll and carotenoids are among the most common plant pigments explored as sensitizers. The review of different attempts on fabrication of natural dye based solar cells implies that titanium dioxide (TiO2) nano particles as photoanode, platinum (Pt) as counter electrode and iodine/iodide electrolyte is the most widely used combination so far. Plant pigments are highly pH sensitive and can alter solar cell performance based on its extraction method, concentration and its ability to anchor with photoanode. Stability of dye, absorption in near IR range and leakage of liquid electrolyte are few of the challenges ahead. However, natural dye is biodegradable and non-toxic having most of the extraction process harmless to environment. In addition, natural dye has the promising future as it is abundant. Genetic engineering will provide means of modifying plant DNA to render desirable concentration and type of plant pigments. Anthocyanin has been studied extensively and gives comparatively higher efficiency in a single dye cell. Co-sensitization can be one of the possible options to enhance solar cell efficiency in future.