| Summary: | Dye-sensitized solar cell using chlorophyllin (C), xanthophylls (X), and the
mixture of two pigments as the sensitizer have been studied. This research
investigated the spectral absorption of the chlorophyllin and xanthophyll mixture
in solution, the dyes capability of sensitizing TiO2 surfaces, and comparing the
DSSC�s efisieciency using blended dyes as well as single dyes of chlorophyllin and
xanthophylls as the sensitizer.
Chlorophyll extract of spinach powder was hydrolysed with 7% KOH in
methanol. Xanthophyll was extracted from fresh petal chrysanthemum with mixed
solvent of absolute ethanol:petroleum eter (60:40). The dyes was blended at various
volume ratios of (C:X) 1:0, 5:1, 1:1, 1:5, and 0:1. The sensitization ability of the
dyes were analyzed by comparing the absorption of the dyes in solution with the
absorption of adsorbed dyes on TiO2 surfaces. While cyclic voltammetry with
ITO/TiO2-dyes as the electrode was used to estimate the oxidation potential of the
dyes in order to calculate the HOMO and LUMO energy of the sensitizer. The cell
efficiency was determined using I-V instrument in sandwich system FTO/TiO2-
dyes as photoanode, FTO/platinum as cathode, and electrolyte redox of I�/I3�.
The absorption spectra of the blending dyes shows no broadening absorption to
longer wavelength. It is due to the near position of absorption peak between
chlorophyllin and xanthophyll so it might be overlapped. The dye sensitization in
TiO2 surface shows that the dyes are capable to sensitize TiO2 via aggregation
effect. The I-V test confirmed that the energy conversion efficiency of the cosensitized
natural dyes (C:X=1:5) resulted higher efficiency (10.5x10-3%) than that
of single dyes of chlorophyllin and xanthophyll which is 2.23x10-3% and 7.3x10-
3%, respectively. The higher efficiency of co-sensitized dyes of chlorophyllin and
xanthophyll probably based on their role of natural photosynthesis mechanism.
Keyword:Co-sensitization, chlorophyllin, xanthophyll, DSSC
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