Application of doping graphene quantum dots and gold nanoparticles on dye-sensitized solar cells

Abstract

The doctor blade coating method is used to prepare dye-sensitized solar cells (DSSCs) and dope the original titanium dioxide (TiO2, P25) photoanode (PA) with single-layer graphene (G), graphene quantum dots (GQDs), and gold (Au) nanoparticles in this research. The results show that doping PAs with G, GQDS, and Au effectively increases the short-circuit current density [Formula: see text], conversion efficiency [Formula: see text], and decreases the internal structure impedance [Formula: see text] of DSSCs. [Formula: see text] increases from 13.62 to 17.02, 15.22, 16.05 mA/cm2, while [Formula: see text] (%) increases from 6.36 to 7.50, 7.08, 7.04% when doping G, GQDs, and Au, respectively. The analysis of Electrochemical Impedance Spectroscopy (EIS) reveals that the doping decreases [Formula: see text] from 11.28 to 8.36, 8.78, 8.54 [Formula: see text], respectively. Then, the titanium dioxide (TiO2)-doped G-GQDs, G-Au, and QDs-Au on DSSCs influence [Formula: see text] that increases to 5.45, 15.37, and 15.31 mA/cm2, respectively. In this case, the values of [Formula: see text] are found to be 7.21%, 7.35%, and 7.00%, while those of [Formula: see text] are 8.44, 8.63, and 9.18 [Formula: see text]. The values of [Formula: see text] and [Formula: see text] are highest but that of [Formula: see text] are lowest when doping with G, which proves that the photoanode of the DSSC effectively activates the photogenerated electrons in the film by doping single-layer graphene and TiO2 captures its electrons through graphene. The decreasing electron–hole recombination rate allows the photogenerated electrons to be quickly transferred to the external circuit. As a result, the efficiency of DSSCs is improved.