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Two major drawbacks in dye-sensitized solar
cells (DSSC) arc the narrow spectral response and the
short-term stability. Research on development of artificial dyes for a broad frequency response is a major field
of research today. The work presented here shows a broad
response with a natural dye extracted from a Mondo-grass
iOphiopogon japonicusi berry. Its range of sensitivity covers the entire visible region and its tail expands to the near
infrared. This is a unique situation since many natural dyes
containing anthocyanin or carotenoids strongly absorbed
only below 600 nrn. A Ti02 based electrode sensitized
with Mondo grass berry dye DSSC was tested for its performance. An open circuit photovoltage or 495 m V and a
short circuit phoiocurrent or 0.6 mJ\/cm7. were obtained
under I sun illumination. The broad spectral response from
400 to 750 nm was observed for the Mondo-grass berry
dye. A high f II factor of 71 % was achieved but energy conversion efficiency was only 0.2% for the cell. Even though
cell efficiency is low with this dye, the solar cells have
exhibited better stability when compared with that of the
Blackberry. The thin layer chromatography results indicate
that Mondo-grass berry dye contains a mixture of two or more chemical compounds belonging to both the .uuhocya
nin and the carotenoid families.
