Chlorophyll and Betalain as Light-Harvesting Pigments for Nanostructured TiO 2 Based Dye-Sensitized Solar Cells

Abstract

Chlorophyll and betalain pigments extracted from scent leaves and flower of Bougainvillea Spectabilis were used as sensitizers for nanostructured TiO 2 based dye-sensitized solar cells (DSSCs), and their perfomances were investigated systematically. The light harvesting pigments have shown absorption in broad range of the visible region of the solar spectrum and appreciable adsorption onto the semiconductor surface. The photovoltaic (PV) parameters such as short circuit current density (J SC), open circuit voltage (V OC), fill factor (FF), and overall solar conversion efficiency (η) were determined under 100 mAcm-2. The DSSC fabricated with betalains pigment from Bougainvillea Spectabilis was found to be superior to that obtained from chlorophyll pigment of scent leave (Ocimum Gratissimum). The DSSC gave a short circuit current density of 0.093 mAcm-2 , open circuit voltage of 0.433 V, fill factor of 0.550, and an overall solar conversion efficiency of 0.040%. The cell sensitized with betalains pigment exhibits: (i) ~ 1.90 times improvement in conversion efficiency, (ii) ~ 2.11 times enhancement in photocurrent density, and (iii) ~ 1.38 times improvement in fill factor compared to the results obtained with the chlorophyll sensitized solar cell. The sensitization performance related to interaction between the dye and TiO 2 surface is discussed.