Integrating graphene and C-60 into TiO2 nanofibers via electrospinning process for enhanced conversion efficiencies of DSSCs

Abstract

Electrospun TiO2 nanofibers incorporated with graphene and C-60 nanoparticles at 0, 1, 2, 4, and 8 wt.% were produced using poly (vinyle acetate), dimetylfomamide, and titanium (IV) isopropoxide. The resultant nanofibers were heat treated at 300 degrees C for 2 hrs in a standard oven to remove all the organic parts of the nanofibers, and then further heated up to 500 degrees C in Ar for additional 12 hrs to crystallize the TiO2 nanofibers. For the graphene and C-60 containing nanofibers, two steps annealing at 300 degrees C (air) and 500 degrees C (Ar) were conducted to eliminate the decomposition processes of the graphene and C-60 in the TiO2 nanofibers. SEM, TEM and XRD studies were conducted on the samples. The results showed that graphene and C-60 were well integrated in the nanofiber structures. The TiO2 nanofibers with the inclusions were mixed in a solution to form a paste, which was then applied on a conductive glass after the TiCl4 solution treatments to make various dye sensitized solar cells (DSSCs). This technique enables creation of solar cells with variable thicknesses of 7 mu m to 45 mu m. The effects of the manufacturing technique, thickness of the paste, different percentages of graphene and C-60 nanoparticles on overall efficiency of the solar cell were studied in detail. The test studies indicated that in the presence of graphene and C-60, the DSSC efficiency increased more than 50%. The present study may guide some of the scientists and engineers to tailor the energy band gap structures of the semiconductor materials for different industrial applications, including DSSCs, as well as water splitting, catalyst, Li-ion batteries, and fuel cells.