Strategic graphene integration in multilayer photoanodes for enhanced quasi-solid-state dye-sensitized solar cells and performance under variable irradiance

Graphene is a potential candidate material to boost efficiency in solar cells. The performance of multilayer TiO₂ photoanode-based quasi-solid-state dye-sensitized solar cells (DSSCs) is improved by strategically integrating graphene into the appropriate layer of the photoanode. For this purpose, graphene was synthesized from vein graphite, received directly from the mine site, providing a cost-effective, feasible, and new approach to enhance DSSC efficiency. Raman and XRD spectra confirm the successful exfoliation of graphite, forming graphene. Graphene integration into layers was analyzed using SEM images. The cells were constructed using photosensitized spin-coated TiO₂ multilayer photoanode, Pt counter electrode, and binary salt gel polymer electrolyte. Appreciable performance improvement was observed when graphene was added to the fourth layer of the photoanode. The quasi-solid-state DSSC without graphene demonstrated 5.50% efficiency, 700 mV open-circuit voltage, 11.04 mA cm⁻² short-circuit current density, and 71.2% fill factor under 1000 W m⁻² irradiation. In contrast, the DSSC improved by graphene exhibited 6.8% efficiency, 13.4 mA cm⁻² short-circuit current density, 770 mV open-circuit voltage, and 66.2% fill factor under 1000 Wm⁻² irradiation. Furthermore, the efficiency and fill factor increase were observed when the irradiance decreased. The DSSC exhibited a remarkable efficiency of 9.4% under 67 W m⁻² irradiance. Achieving higher efficiency for quasi-solid-state configuration without relying on volatile solvent-based electrolytes is another significance of this study. The study uncovers that the strategic incorporation of graphene, synthesized in an economically viable manner, into specific layers of the photoanode significantly enhances the power conversion efficiency in DSSCs.