Abstract:
The co-sensitization method is employed in dye sensitized solar cells (DSSCs), with the
aim of improving the absorption of light over a border wavelength region and thereby to
improve the current output of the devices and the overall efficiency. In this work, natural
pigments from the fire fern leaves and begonia black velvet leaves were used for double
layered co-sensitization in dye sensitized solar cells (DSSCs). UV-VIS Spectral data
revealed that both dyes were anthocyanins. The co-sensitization was done by first
adsorbing the dye from begonia black velvet on to a TiO2 electrode by dipping, and then by
removing the adsorbed dye of the top layer of TiO2 using a de-sorption solution. After that
the fire fern dye was allowed to adsorb. The best performance was exhibited by the cosensitized
cell which showed conversion efficiency (η) of 1.2%, with open circuit voltage of
412.9 mV, short circuit current density of 5.08 mAcm-2 and fill factor of 57.2%. This
performance is superior to that of either individual devices made from fire fern (η=0.96%)
and begonia black velvet (η=0.87) under the same conditions of fabrication.
