Natural solvent facilitated high-shear exfoliated graphene nanoplatelets enabled economically-efficient and stable DSSC

This work presents an efficient and stable platinum-free shear-exfoliated graphene nanoplatelets (SE-GNP) based counter electrode (CE) for dye-sensitized solar cells (DSSCs). The SE-GNP is prepared by the simple, low cost and eco-friendly high-shear liquid-phase exfoliation technique in bulk using natural graphite flakes as a starting material in an aqueous medium. Detailed electrochemical studies demonstrate that SE-GNP-based CE offers a superior electrocatalytic activity for the redox reaction of I⁻/I<inf>3</inf>⁻ redox couple with an improved charge transfer kinetics and the exchange current density at the electrode/electrolyte interface, compared to the standard Pt CE. The SE-GNP-based counter electrode shows exceptionally high stability (>3000 h) and efficiency (ƞ = 7.6%) under constant illumination at a negligible drop in DSSCs' performance.