Dye - sensitized solar cells: using over 100 natural dyes as sensitizers

Over 100 natural dyes extracted from fruits, leaves, flowers, stems, bark and roots of plants growing in Sri Lanka were used as sensitizers of to fabricate dye-sensitized solar cells (DSSC's). Preliminary investigations on the identification of natural pigments in the dye-sensitization of nanocrystalline n-type Ti02 were carried out. Fresh extracts of various fruits and vegetables were employed as sensitizers in thin layer sandwich type photo electrochemical dye - sensitized solar cells (DSSC's). After electrical and electronic analysis, of several natural dyes of local plants, it was observed that many useful dyes which could be extracted from natural products by simple procedure could be used as photo sensitizers for DSSC's. It was also observed that dye extracts of Mangoostein yielded better results. The current-voltage curves obtained with solar cells employing the photo anode with Ti02 sensitized by different dyes were observed. The values of short circuit current density (Jsc), open circuit voltage (Voc), fill factor (ff), and efficiency fa) obtained for solar cells employing photo anodes with Ti02 sensitized with different fruit / vegetable extracts were noted. The dye extracts of Mangoostein fruit were found to be superior to those obtained from other dyes , and were Jsc = 2.56mAcm2, Voc 6S5.3 mV, ff = 60.02 %,n = 1-053 %. Also Ekkiriya wood, Egg Plant, Karawilla kabilla yielded Jsc, Voc, ff and /? of 2.32 mA.cm2, 414.2mV, 56.86%, 0.547% respectively; 2.096 mA.cm2, 410.4mV, 56.42%, 0.485%; 1.395 mA.cm2, 443.5mV, 58.58% and 0.362%. Whilst Fire Fern (not endemic to Sri Lanka) was found to display Jsc, Voc, ff and rj of 128mA.cm2,405.1mV, 47.97% and0.802% respectively. /si