ABSTRACT
Dye-sensitized solar cells (DSCs) are regarded as the nextgeneration solar cells due to the low fabrication cost and decent power conversion efciency. A DSC is usually consisted of a work electrode, a counter electrode, and electrolyte between the two electrodes. It has been reported that graphene and graphene oxide (GO) have important application in all the three parts of DSCs. Their applications are reviewed in this chapter. Graphene sheets are incorporated into the mesoporous TiO2 work electrode of DSCs. They facilitate the electron transport across the TiO2 nanoparticles (NPs) and thus increase the photovoltaic efciency of DSCs. GO has many oxygen-containing groups, including hydroxyl and epoxy. The oxygen-containing groups can have strong interaction with the surface species of TiO2 nanoparticles. It was exploited as an auxiliary binder for TiO2 NP paste that was used for the fabrication of mesoporous TiO2 work electrode. Continuous crack-free thick TiO2 lms can be prepared by a single printing of a TiO2 NP paste added with GO. However, threefold or fourfold printings are needed for TiO2 pastes without GO. Thus, GO can signi- cantly improve the device fabrication efciency and lower the fabrication cost of DSCs. There are rigid domains consisted of conjugated C═C bonds and exible domains comprising oxygen-containing groups. The oxygen-containing groups can have strong interaction with polar organic solvents. GO can thus serve as a gelator for polar organic solvent. GO was also used as a gelator for the gel electrolyte. DSCs with GO gel electrolyte can have high photovoltaic efciency close to control DSCs with liquid electrolyte, whereas the former have much better photovoltaic stability. Graphene is conductive and catalytic to the regeneration of the redox species in the electrolyte. It was investigated to replace Pt, a noble metal,
as the counter electrode of DSCs. The DSCs with graphene as the counter electrode can have high photovoltaic efciency close to the control DSCs with Pt counter electrode. Graphene composites, including graphene-metals, graphene-oxides, graphene-sulde, graphene-carbon nanotubes (CNTs), and so on, were also studied as the counter electrode of DSCs. The composites of graphene and CNTs signicantly overperform Pt as the counter electrode of DSCs in terms of the photovoltaic efciency and stability.
