Composite electrolyte pastes for preparing sub-module dye sensitized solar cells

In this study, high-efficiency sub-module quasi-solid-state (QS) dye-sensitized solar cells (DSSCs) are prepared using silicon dioxide (SiO₂) nanofiller and polyethylene oxide (PEO)-based iodide composite electrolyte pastes. The influence of various amounts of nanofiller on the ionic conductivity, ion diffusion coefficient, and the performance of the devices are explored. The addition of SiO₂ decreases the ion transport properties in the plain polymer electrolyte pastes. X-ray photoelectron spectroscopy analysis confirms the adsorption of polyiodide and lithium ions on the surface of the SiO₂. This effect causes a reduction in the concentration of ions near the photoelectrode. As a result, the QS-DSSCs using 1 wt.% SiO₂ nanofillers have higher recombination resistance and a longer electron lifetime than the other DSSCs. Therefore, high open-circuit voltage (0.794 V) and high efficiency (8.83%) are obtained for the corresponding QS-DSSCs. This efficiency is much better than the efficiencies of the devices employing the pristine polymer electrolyte paste and liquid electrolytes. This composite electrolyte paste is employed to prepare QS-sub-module cells. The four strip and rectangular-shaped module cells have high efficiencies of 4.71% and 4.81%, respectively. QS-DSSCs using 1 wt.% SiO₂ nanofillers show high stability at both room temperature and 60 °C.