Dye Sensitized Solar Cells Using Natural Pigments from Five Plants and Quasi-Solid State Electrolyte

Dye-sensitized solar cells (DSSCs) were fabricated using natural dyes extracted from flowers of Amaranthus caudatus, Bougainvillea spectabilis, Delonix regia, Nerium oleander, Spathodea companulata and a mixture of the extracts. The photoelectrochemical cell (PEC) performance of the DSSCs of these dyes showed fill factors (FF) mostly higher than 50%, the open circuit voltages (V_OC) varied from 0.45 to 0.55 V, and the short circuit photocurrent-densities (J_SC) ranged from 0.013 to 1.82 mA cm⁻². High open circuit voltage (V_OC = 0.55 V) and short circuit photocurrent-density (J_SC = 1.82 mA cm⁻²) were obtained from the DSSC sensitized by the ethanol extract of flower of Amaranthus caudatus. The power conversion efficiency (η) of the DSSC with the ethanol extract of Amaranthus caudatus flower reached 0.61%. The PEC performances of DSSCs of mixed dye solutions were also investigated. However, the mixed extract does not show any synergistic photosensitization compared to the individual extracts. Instead, the cell sensitized by the ethanol extract of Amaranthus caudatus flower alone showed the best performance. The devices showed incident monochromatic photon-to-current conversion efficiencies (IPCE) varied from 4.7% to 52%. The results from the IPCE data are consistent with the results from the (J-V) curves.

dye sensitized solar cells; natural pigments; quasi-solid state electrolyte