The production of organogels using graphene oxide as the gelator for use in high-performance quasi-solid state dye-sensitized solar cells

We report the formation of organogels of 3-methoxypropionitrile (MPN) using graphene oxide (GO) as the gelator and the use of these gels as the quasi-solid state electrolyte of dye-sensitized solar cells (DSCs). GO–MPN gels are prepared by mechanically grinding or ultrasonicating GO in MPN. The GO sheets form 3-dimensional solid networks in the gels, which hold the MPN solvent. The GO loading can be as low as 2.5 wt.% for the gel formation. Gel electrolytes were prepared by dispersing I2, 1-methyl-3-propylimidazolium iodide, guanidine thiocynate and 4-tert butyl pyridine into GO–MPN gels, and these were used for DSCs. The GO sheets can be fragmented into small pieces by ultrasonication, and smaller GO sheets can lead to a higher diffusion constant of the triiodide and a higher photovoltaic efficiency for the DSCs. DSCs with a GO–MPN gel electrolyte exhibit a photovoltaic efficiency of 6.70% under AM 1.5 G illumination (100 mW cm−2), quite close to that (7.18%) of the control liquid DSCs.