Abstract
The aims of this research are the preparation and characterization of the graphene-based nanocomposite electrodes for their use in working electrode and counter electrode of dye-sensitized solar cells (DSSCs). This dissertaion contains four parts including: (1) preparation and properties of graphene/acid-MWCNTs hybrids applied to working electrode, (2) preparation and properties of the Pt nanoparticles/graphene nanocomposite counter electrode for DSSCs, (3) preparation and properties of the metal-free nitrogen-doped graphene nanocomposite counter electrode for DSSCs and (4) preparation and properties of the MWCNT/graphene hybrid materials for counter electrode of DSSCs. First part of this dissertation aims to prepare the graphene/acid-MWCNTs hybrids with high dispersibility. In this part, a novel method was proposed to improve the dispersion characteristics of thermally-reduced graphene through the incorporation of acid-MWCNTs. The photocurrent density of DSSCs using a hybrid material photoanode was increased by 35% and the conversion efficiency was increased by 31%, compared to DSSCs using a pristine TiO2 photoanode. This was due to the increased quantity of adsorbed dye which will reduce the charge transfer resistance and enhance electron transport rate, resulting from the incorporation of hybrid material. The second part of the dissertation investigated the electrocatalytic properties of Pt nanoparticles/graphene nanocomposite material for counter electrode of DSSCs. The photocurrent density of DSSCs that used a PtNP/GR counter electrode was increased by 13%, and the conversion efficiency was increased by 20%, compared with DSSCs that used a platinized FTO. This was due to the increased charge transfer rate and reduced internal resistance that resulted from the incorporation of a PtNP/GR composite. The third part of the dissertation studied the electrocatalytic properties of nitrogen-doped graphene (NGR) nanocomposite material for counter electrode of DSSCs. The DSSCs fabricated using the NGR counter electrode showed a comparable result in performance compared with those fabricated using the platinized counter electrodes, showing only 6 % decrease in conversion efficiency. This was due to the charge transfer rate was increased and internal resistance was reduced that resulted from the incorporation of a NGR composite. The fourth part of the dissertation investigated the characterization of potential candidate, MWCNT/graphene (GC) nanocomposite materials, for counter electrode of DSSCs. The DSSCs fabricated using the GC counter electrode showed a comparable result in performance compared with those fabricated using the platinized counter electrode, showing 8.4 % decrease in conversion efficiency. This was due to the charge transfer rate was increased and internal resistance was reduced resulting from the incorporation of a GC composite.