Abstract:
Morphology of the photoanode in Dye Sensitized Solar Cells (DSSCs) is one of the crucial factors
determining their overall efficiencies. Despite the use of composites with other semiconductors or the
modification of the morphology of the material, the efficiency enhancement of these devices can be
achieved by increasing the light harvesting rate of the photoanode. On the other hand, harvesting of
photon energies in full solar spectrum by co-sensitization of photoanodes is another approach towards the
efficiency enhancement in these devices. Here we report the possibility of enhancing the efficiency of DSSC
by employing a co-sensitized triple layered photoanode with electrospun nanofibres (NF) and nanoparticles
(NP) of TiO2. Performances of DSSCs comprising with TiO2 NP/NF/NP triple layered structures were
compared with the devices fabricated with conventional NP TiO2 photoanodes under the identical
conditions by using inexpensive Eosin-Y and Rose Bengal dyes. Dramatic enhancement in the efficiency of
DSSC was obtained due to the incorporation of the NF layer. DSSCs fabricated with Eosin–Y dye sensitized
triple layered structure showed 1.77% overall efficiency whilst the cells fabricated with the conventional
photoanodes showed 0.89% efficiency thus giving an increase in efficiency by 98% under the irradiance
of 1000 W m-2. DSSCs sensitized with Rose Bengal dye showed 0.25% and 0.76% efficiencies with
conventional and triple layered photoanodes respectively. UV-Vis absorption measurements suggest that
the main cause for this improvement could be due to the enhanced light harvesting by scattering effect
within the electrospun TiO2 NF layer. While the DSSC fabricated with co-sensitized TiO2 NP/NF/NP photo
anode showed energy conversion efficiency of 2.09%, the cells fabricated with co-sensitized conventional
photoanode showed an efficiency of 1.04%. Incorporation of triple layered co-sensitized photoanode
enhanced the efficiency of DSSCs by two fold.
