Red Sicilian orange and purple eggplant fruits as natural sensitizers for dye-sensitized solar cells

Dye-sensitized solar cells (DSSCs) were assembled by using red Sicilian orange juice (Citrus Sinensis) and the purple extract of eggplant peels (Solanum melongena, L.) as natural sensitizers of TiO2 films. Conversion of solar light into electricity was successfully accomplished with both fruit-based solar cells. The best solar energy conversion efficiency (Z ¼ 0.66%) was obtained by red orange juice dye that, under AM 1.5 illumination, achieved up to Jsc ¼ 3.84 mA/cm2, Voc ¼ 0.340 V and fill factor ¼ 0.50. In the case of the extract of eggplant peels, the values determined were up to Jsc ¼ 3.40 mA/cm2, Voc ¼ 0.350V and fill factor ¼ 0.40. Cyanidine-3-glucoside (cyanine) and delphinidin 3-[4-(p-coumaroyl)-L-rhamnosyl(1-6)- glucopyranoside]-5-glucopyranoside (nasunin) are the main pigments of cocktail dyes for red orange and eggplant, respectively. Actually, their application is far below the industrial requirements. Nevertheless, their study is an interesting multidisciplinary exercise useful for dissemination of knowledge and to educate people on renewable energy sources. Here, we report and discuss the role of the structure, the absorption spectra and the sensitization activity of the mentioned compounds.