| Critical assessment of economically viable renewable energy sources is essential for the development of a globally sustainable society. Dye sensitized solar cells (DSSCs) offer a viable alternative to traditional silicon and thin film photovoltaic (PV) technologies owing to their potential low cost and facile manufacturing. The two main challenges in enhancing device cell performance lie in improving the open circuit voltage (VOC), and suppressing recombination in the semiconductor TiO2 matrix. This thesis explores the latter challenge through investigation of a novel microstructured TiO2 photoanode system.;In this research, we have synthesized CTAB-templated mesoporous, anatase, high surface area TiO2 using an acidic precursor to enhance dye adsorption. Through simple supramolecular self-assembly of the TiO2 particles during the synthesis, we have discovered a self-assembled system of TiO2 nanocrystallite aggregates with high surface area, which when applied as the photoanode in DSSCs, result in a novel high-roughness film beneficial for dye adsorption, and also lead to enhanced intrinsic light-scattering within the film itself. The TiO2 nanocrystallites are highly crystalline, with good interconnectivity for improved electron conduction. An additional unique and beneficial feature inherent of this novel photoanode film is its hierarchical meso- and macro-porosity, leading to improved electrolyte percolation through the TiO2 matrix---thereby providing better access to dye molecules for regeneration to occur more effectively (enhanced charge transfer). In all, we have fabricated a TiO2 system through a one-step process that incorporates key beneficial microstructural features crucial for enhancing DSSC behavior.;We have further carried out critical TiCl4 surface treatment studies of this porous electrode structure of TiO2 aggregates to understand and improve upon recombination kinetics in the photonanode film matrix, together with enhancing its intrinsic light harvesting features. We have found this surface treatment to be a powerful one-step method to simultaneously enhance as well as provide insight into the beneficial microstructural features of our unique TiO2 photoanode system. Improved efficiency was observed when compared to cells prepared using standard Degussa P25 TiO 2 electrodes of similar thickness. |
