Oligomeric Ruthenium Light Absorbers and Nanostructured Lenses for Improved Harvesting of Solar Energy
Open Access
Author:
Gray, Christopher
Graduate Program:
Chemistry
Degree:
Doctor of Philosophy
Document Type:
Dissertation
Date of Defense:
October 08, 2019
Committee Members:
Thomas Mallouk, Dissertation Advisor/Co-Advisor Thomas Mallouk, Committee Chair/Co-Chair John B Asbury, Committee Member Raymond Edward Schaak, Committee Member Akhlesh Lakhtakia, Outside Member Philip C Bevilacqua, Program Head/Chair
Keywords:
photoelectrochemical cells water-splitting solar energy solar fuels nanomaterials oligomer ruthenium polypyridal
Abstract:
Water-splitting dye-sensitized photoelectrochemical cells (WS-DSPECs) rely on molecular sensitizers to harvest light energy and drive the catalytic reactions necessary to generate hydrogen and oxygen from water. The desorption of sensitizer molecules from the semiconductor-aqueous electrolyte interface is a significant barrier to the practical implementation of these cells. To address this problem, we synthesized a novel oligomeric ruthenium dye ([RuP]n) which has dramatically improved stability as a photosensitizer for TiO2 electrodes over the pH range of interest (4 to 7.8) for DSPECs. Additionally, the efficiency of photoelectrochemical charge separation is known to depend on the rate of cross-surface hole diffusion between dye molecules.20,21 The oligomeric dye ([RuP]n) also shows an order of magnitude faster cross-surface hole diffusion than the commonly used monomeric [Ru(bpy)2(4,4-PO3H2)2bpy)]2+ (RuP) sensitizer. The enhanced stability of the polymeric dye also enables the use of intensity-modulated photovoltage spectroscopy (IMVS) to measure the recombination rate of photogenerated electrons and holes as a function of electrolyte pH.