Natural dye sensitizers for photoelectrochemical cells

In nature, fruit, vegetable, leaves, flowers and algae contain several dyes which can be easily extracted and employed in dye sensitized photoelectrochemical cells. In this contribution, the most significant advances made in the search for efficient and convenient natural sensitizers are reported through meaningful examples and case studies. To date, selected chlorophyll derivatives, raw anthocyanine and betalain extracts are the most successful natural sensitizers, resulting in the generation of monochromatic photon to current conversion yields exceeding 60%. Maximum overall conversion efficiencies above 2% under simulated sunlight have been achieved, which is comparable to that of natural photosynthesis. Finding appropriate additives for improving VOC without causing dye degradation might result in a further enhancement of cell performance, making the practical application of such systems more suitable to economically viable solar energy devices for our society.