Ionic liquid-functionalized graphene quantum dots as an efficient quasi-solid-state electrolyte for dye-sensitized solar cells

摘要

In this study, graphene quantum dots (GQDs) functionalized with ionic liquid (IL) were introduced as an efficient quasi-solid-state hybrid electrolyte for dye-sensitized solar cells. The GQDs have been covalently functionalized with imidazolium-based IL (GQDs-IL), and the resulted hybrid electrolyte has been characterized by FT-IR, ~1H- and ~(13)C-NMR, XRD, fluorescence spectroscopy, zeta potential and thermogravimetric analysis. The power conversion efficiency of the prepared electrolytes from GQDs, IL and GQDs-IL under the simulated AM 1.5 solar spectrum irradiation at 100 mW cm~(-2) in the fabricated dye-sensitized solar cells (DSSCs) was found to be 2.24, 4.52 and 4.58% respectively. The short-circuit current density of the DSSC with GQDs-IL-based electrolyte was calculated to be 19.57 mA cm"2 which was remarkably more than GQDs and IL. According to Bode plots, the use of GQDs in the final electrolyte increased the electron life time and reduced the recombination reaction to the redox couple due to the inhibition of the back-electron transfer to the electrolyte. Upon the superior long-term stability and highest photoelectric conversion efficiency of the developed GQDs-IL electrolyte, the fabricated DSSCs could overcome the drawbacks of volatile liquid electrolytes.