Graphene oxide as auxiliary binder for TiO2 nanoparticle coating to more effectively fabricate dye-sensitized solar cells

In this paper, we report a novel method to effectively fabricate the mesoporous TiO2 films of dye-sensitized solar cells (DSCs) by formulating new TiO2 pastes. Graphene oxide (GO) is added into TiO2 nanoparticles pastes as an auxiliary binder. Thick mesoporous TiO2 films free of crack can be prepared by only single printing. TiO2–GO pastes and films were characterized by dynamic mechanical analysis, X-ray photoelectron spectroscopy (XPS), scanning electron microscopy (SEM), X-ray diffraction (XRD), thermogravimetric analysis (TGA), and FTIR spectroscopy. TiO2 pastes added with GO exhibit gel behavior. GO helps bind TiO2 nanoparticles together through the interactions between functional groups on GO and the surface species of TiO2 nanoparticles. The presence of 0.8 wt.% GO in the TiO2 paste (GO weight percentage with respect to the weight of TiO2) is sufficient to fabricate thick and crack-free TiO2 films via single printing. These mesoporous TiO2 films fabricated from the TiO2–GO pastes are investigated as the anode of DSCs. They can give rise to a power conversion efficiency (PCE) of 7.70% for DSCs under AM1.5G illumination, which is almost the same as that of control devices with the TiO2 mesoporous electrode fabricated from the conventional TiO2 paste without GO via four-fold printings.