Browsing by Author "Jara, Desalegn"

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    Screening of Natural Dyes for Use in Dye Sensitized Solar Cells
    (Addis Ababa Universty, 2012-06) Jara, Desalegn; Yohannes, Teketel (Professor)
    Five natural dyes, extracted from natural materials such as flowers, were used as sensitizers to fabricate dye-sensitized solar cells (DSSCs). Dye-sensitized solar cells (DSSCs) were fabricated using natural dyes extracted from flowers Amaranthus caudatus, Bougainvillea spectabilis, Delonix regia, Nerium oleander, Spathodea companulata and a mixture of the extracts. The PEC performance of the DSSCs based on these dyes showed that the fill factors of these DSSCs are mostly higher than 50%, the open circuit voltages (VOC) varied from 0.45 to 0.55 V, and the short circuit photocurrent densities (JSC) ranged from 0.013 to 1.82 mAcm−2. Specifically, a high open circuit voltage (VOC = 0.55 V) and short circuit photocurrent density (JSC = 1.82 mAcm−2) were obtained from the DSSC sensitized by the ethanol extract of flower of Amaranthus caudatus. The photon to electricity conversion efficiency of the dyesensitized solar cell (DSSC) sensitized with the ethanol extract of flower of Amaranthus caudatus reached 0.61%. The PEC performances of DSSCs using the dye mixed solutions were also investigated. However, the mixed extract does not show synergistic photosensitization compared to the individual extracts. Instead, the cell sensitized by the flower of Amaranthus caudatus extract extracted with ethanol alone showed the best sensitization. The devices showed that an incident monochromatic photon to current conversion efficiencies (IPCE) varied from 4.7% to 52% illuminated from front side. The results from the IPCE data are consistent with the results from the current density ‒ voltage (J − V) curves.