Self-assembled TiO ₂ with increased photoelectron production, and improved conduction and transfer: Enhancing photovoltaic performance of dye-sensitized solar cells

Highly crystalline mesoporous anatase TiO ₂ is prepared through supramolecular self-assembly and by utilizing cetyltrimethylammonium bromide (CTAB) as templating material. Photoanodes of dye-sensitized solar cells (DSSCs) made from these TiO ₂ nanoparticles are found to have a high specific surface area of 153 m ²/g and high surface roughness. Optical absorption spectroscopy studies reveal that the photoanode films adsorb four times more dye than films made of commercial P25 TiO ₂. Mercury porosimetry and field emission scanning electron microscope (FESEM) studies show hierarchical macro- and meso-porosity of the photoanode films leading to better dye and electrolyte percolation, combined with improved electron conduction pathways compared to P25 films. Electrochemical impedance studies confirm lower impedance and higher electron lifetime in the synthesized mesoporous TiO ₂ films compared to P25 films. Higher photovoltaic efficiency was recorded of cells made from the synthesized mesoporous TiO ₂ in comparison to the corresponding cells made from P25. Incident-photon-to-current efficiency data provided critical understanding of recombination kinetics, and provided proof of Mie scattering by the self-assembled submicrometer sized TiO ₂ aggregates and the macropores in their structure. The scattering phenomenon was further corroborated by diffused reflectance studies. An in-depth analysis of CTAB-templated mesoporous TiO ₂ has been conducted to show how it can be a good candidate photoanode material for enhancing the performance of DSSCs.