Recent developments in Dye Sensitized Solar Cells using betalain and anthocyanins as sensitizers extracted from fruits and flowers.

Dye sensitized solar cells (DSCs) are devices for the conversion of visible light into electricity based on sensitization of wide band-gap semiconductors. Recent developments in DSCs using natural pigments containing betalains and anthocyanins as TiO2 photosensitizers are presented. Conversion of solar light into electricity was successfully accomplished, showing a maximum photon to electron conversion efficiencies (IPCE) exceeding 40% for most of the investigated dyes. The selected dye extracts were obtained from grape, cherry, mulberry, red Sicilian orange, red turnip, Indian fig, eggplant etc. The best overall solar energy conversion efficiency was observed with the red turnip extract that, under AM 1.5 illumination, achieved up to 1.7% of global efficiency, showing a remarkable current density (Jsc = 9.5 mA/cm2). Also the purple extract of the wild cactus pear and the mulberry fruit showed interesting performances, with a solar to electrical power conversion of 1.26 % and 1.19% respectively. Although presently natural DSCs are still below the efficiency requirements for practical applications, our results indicate that, in the future, non toxic and fully biodegradable natural sensitizers might be potentially exploited to enhance the economic benefits of solar energy