The impact of a TiO2/r-GO composite material on the performance of electron transport electrodes of dye sensitized solar cells

Abstract

In dye sensitized solar cells, the role of the electron transport layer is crucial because it makes it easier for photo-generated electrons to get from the dye to the external circuit. In DSSCs, the utilization of TiO₂ is likely to be given preference in the production of electron transport electrodes due to its notable characteristics such as its expansive surface area, porosity, and capacity to scatter light. Nevertheless, the presence of heterogeneity within the mesoporous structure increases the likelihood of TiO₂ aggregation, which subsequently diminishes the beneficial impact of TiO₂ on the performance of DSSCs. In this context, reduced graphene oxide (r-GO) is introduced as an additive into the TiO₂ network during the preparation of TiO₂/reduced graphene oxide (r-GO) composites. The integration of r-GO with TiO₂ has been recognized as a promising approach to enhance electron transport and electron lifespan, owing to remarkable qualities exhibited by r-GO. The present investigation involved the synthesis of a composite material including titanium dioxide/reduced graphene oxide (TiO₂/r-GO) through the utilization of the co-precipitation technique. Following this, the generated TiO₂/r-GO composite material and pure TiO₂ were deposited on FTO through electrophoretic deposition to obtain an electron transport electrode of a dye sensitized solar cell. It should be noted that when r-GO was combined with TiO₂, the performance of DSSCs improved notably compared to pure TiO₂. As a result, the findings of this work have significant implications for the advancement of the TiO₂/r-GO composite deposited through electrophoretic deposition. The power conversion efficiency reached 6.64% with the addition of r-GO in the metal oxide electron transport electrode. The obtained findings align with the outcomes of electrochemical impedance investigations in which the electrode constructed with TiO₂/r-GO exhibits reduced electron transport resistance (R_Ct) at the anode/dye/electrolyte interface, as well as lower overall resistance (R_total) in comparison to TiO₂-based DSSCs. These advancements have the potential to be employed in commercial DSSC manufacturing.