High-efficiency,
stable bifacial dye-sensitized solar cells (DSSCs) are prepared for
application under indoor light conditions. A 3-methoxypropionitrile
solvent and cobalt redox couples are utilized to prepare the electrolytes.
To obtain the best cell performance, the components of the DSSCs,
including electrolytes, photoanodes, and counter electrodes (CEs),
are regulated. The experimental results indicate that an electrolyte
comprising a Co (II/III) ratio of 0.11/0.025 M, 1.2 M 4-tert-butylpyridine, Y123 dye, a CE with the platinum (Pt) layer thickness
of 0.16 nm, and a photoanode with titanium dioxide (TiO2) layer thickness of 10 μm (6 μm main layer and 4 μm
scattering layer) are the best conditions under which to achieve a
high power conversion efficiency. It is also found that the best cells
have high recombination resistance at the photoelectrode/electrolyte
interface and low charge transfer resistance at the counter electrode/electrolyte
interface, which contributes to, respectively, the high current density
and open-circuit voltage of the corresponding cells. This DSSC can
achieve efficiencies of 22.66%, 23.48%, and 24.52%, respectively,
under T5 light illumination of 201.8, 607.8, and 999.6 lx. For fabrication
of bifacial DSSCs with a semitransparent property, photoanodes without
the TiO2 scattering layer, as well as an ultrathin Pt film,
are utilized. The thicknesses of the TiO2 main layer and
Pt film are reregulated. This shows that a Pt film with 0.55 nm thickness
has both high transmittance (76.01%) and catalytic activity. By using
an 8 μm TiO2 main layer, optimal cell efficiencies
of 20.65% and 17.31% can be achieved, respectively, for the front-side
and back-side illuminations of 200 lx T5 light. The cells are highly
stable during a long-term performance test at both 35 and 50 °C.
