N3 dye is a light-harvesting chromophore frequently used in energy devices such as dye-sensitized solar cells and photoelectrochemical cells.  The orientation and structure of this Ruthenium-based light-harvesting chromophore in such architectures can greatly impact the electron transfer kinetics in a device, and thus, its overall efficiency. We employ heterodyne-detected vibrational sum frequency generation (HD-VSFG) spectroscopy to investigate the impact of pH conditions on the loading of N3 dye onto a gold and TiO<sub>2</sub> electrodes.  We observe changes to the adsorption geometry of N3 on the electrodes which is a direct result of a changing the pH of the sensitizing solution.  By monitoring the carboxylic acid (COOH) and isothiocyanate (SCN) vibrational modes of N3, we can assign the protonation state of the N3 and its orientation at the interface simultaneously.  The absolute orientation of N3 dye at the electrode surface is extracted from an orientational analysis of polarization-dependent HD-VSFG spectra.

Connecting interfacial structures of dye-electrode systems to processing conditions with heterodyne-detected vibrational sum frequency generation (HD-VSFG) spectroscopy

ACS Fall 2021

The official archive and repository for all ACS Meetings & Expositions abstracts and select posters or presentations.