Outdoor Photoelectrochemical Characterization of Dyes from Acalypha wilkesiana ‘Haleakala’ and Hibiscus sabdariffa as Dye Solar Cells Sensitizers

An outdoor study on the photoelectrochemical performance of dye-sensitized solar cells (DSSCs) with extracts of leaves of Acalypha wilkesiana ‘Haleakala’ and flowers of Hibiscus sabdariffa as sensitizers was undertaken in which the latter was used as a bench mark. Three extraction methods of natural dyes, namely; aqueous, cold ethanol, and Soxhlet hot ethanol, were employed to investigate their impact on the performance of the dye sensitized solar cells. Aqueous and Soxhlet hot ethanol extracts performed the best for Hibiscus sabdariffa and Acalypha wilkesiana ‘Haleakala’ respectively. Hibiscus sabdariffa yielded the averaged photoelectrochemical performance of light-to-current conversion efficiency (η) of 0.07%, open circuit voltage (Voc) of 0.44 V, short circuit current density (Jsc) of 0.23  mA/cm2; and Acalypha wilkesiana ‘Haleakala’ yielded 0.06% efficiency, Voc of 0.40 V, Jsc of 0.26 mA/cm2. The study for Acalypha wilkesiana ‘Haleakala’ further included varying dye concentrations by dilution. It was found out that the dilution factor Df of 10 (ratio of 1:9) was optimum at which the best efficiency was achieved.