Flexible dye-sensitized solar cells
on plastic substrates have
achieved a conversion efficiency of 8.6% with the hot compression
technique (<150 °C). However, the value of efficiency is only
70% of that achieved using glass substrates with high-temperature
sintering technique (500 °C). Investigating the origin of this
difference is a critical step for further improving the performance
of plastic dye-sensitized solar cells. In this study, an optimized
ternary viscous titania paste without the addition of organic binders
enables the fabrication of efficient dye-sensitized solar cells with
a low-temperature process. Therefore, the electron-transport behavior
of dye-sensitized solar cells can be directly compared with those
prepared with the high-temperature sintering technique. In addition
to the structural and optical differences, the hot compressed photoanode
of dye-sensitized solar cells have an electron diffusion coefficient
that is 2 times smaller and a recombination time that is 6 times shorter
than those of the high-temperature sintered cells, suggesting inadequate
interparticle connections and more recombination events. These results
indicate that electron transport and recombination are still the key
factors governing the performance of low-temperature fabricated dye-sensitized
solar cells. Eventually, the flexible cell with an efficiency of 6.81%
has been achieved on flexible indium tin oxide/polyethylene naphthalate
substrate. Further improvements in advanced low-temperature processing
or novel materials with minimized defect or grain boundaries are required
