Nanoporous TiO₂/SnO₂/Poly(3,4-ethylene-dioxythiophene): Polystyrenesulfonate Composites as Efficient Counter Electrode for Dye-Sensitized Solar Cells.

Abstract

PSS) was developed as an alternative counter electrode for dye-sensitized solar cell (DSSC) through low-temperature process. The TiO₂/SnO₂ template was first fabricated by coating a homogeneous TiO₂ nanoparticles blended paste containing a SnCl₄ aqueous solution on the conductive substrate, followed by annealing at 150 °C. The counter electrode was then completed by spin-coating the PSS aqueous solution into the template and drying at 80 °C. The obtained TiO₂/SnO₂/ PSS (TSP) composite film exhibits more excellent catalytic activity for the tri-iodide reduction than the pristine PSS film, resulting in the significant improvements in the fill factor and efficiency of the cells. The values of the fill factor and efficiency respectively increase from 0.564 and 4.79% to 0.699 and 6.54%. Noted that the photovoltaic performances of the TSP based DSSC is very similar to those of the Pt based one. The fill factor and efficiency of the later are 0.696 and 6.48%, respectively. The outstanding properties of the TSP composite film used as the counter electrode can be ascribed to its prominent synergistic effects. In the TSP composite film, the conducting TiO₂ is applied as the main skeleton material with the in-situ formed SnO₂ as a binder to construct a nanoporous structure for the PSS coating and also to provide numerous high-speed conductive paths for the electron transportation from the substrate to the PSS coating, and the PSS adhered on the TiO₂/SnO₂ skeleton mainly acts as the catalyst to enlarge its surface area allowing for more active sites for the tri-iodide reduction.