Preliminary optimization of low-cost quasi solid-state dye sensitized solar cells with multilayer photoanodes, and graphite-based counter electrodes

Investigation and development of platinum free counter-electrodes are highly important in preparing low-cost Dye-Sensitized Solar Cells (DSSCs). In this study, low-cost graphite and TiO₂ composite counter-electrodes are investigated along with photo-electrodes containing dye-photosensitized (N719) TiO₂ multilayers (five, six, and seven layers).

 

The highest DSSC efficiency is observed for the cells assembled using the counter-electrode that contains 80% of graphite and 20% TiO₂, for all the multilayer photo-electrode series investigated. When comparing different series of multilayer photo-electrodes assembled with this optimized counter-electrode composition, the DSSC efficiency for the six-layer series is greater than the five and seven-layer electrodes.

 

This best composition of electrodes optimizes the efficiency by fine-tuning between the charge carrier transport properties and catalytic activity of the electrode. The graphite content plays a significant role due to its catalycity. In 3 hours under irradiation, open-circuit voltage got reduced by 8.0%, while the current density and efficiency got improved by 43.2% and 7.0%, respectively, as observed for the cells with the optimum electrode combination. It can be determined that Graphite/TiO2 80%/20% counter-electrodes with sixlayerphotoelectrodes optimize the performance of platinum free low-cost DSSCs.