Charge transfer from an adsorbed ruthenium-based photosensitizer through an ultra-thin aluminium oxide layer and into a metallic substrate

Andrew J Gibson; Robert H Temperton; Karsten Handrup; Matthew Weston; Louise C Mayor; James N O'Shea

doi:10.1063/1.4882867

Charge transfer from an adsorbed ruthenium-based photosensitizer through an ultra-thin aluminium oxide layer and into a metallic substrate

J Chem Phys. 2014 Jun 21;140(23):234708. doi: 10.1063/1.4882867.

Authors

Andrew J Gibson¹, Robert H Temperton¹, Karsten Handrup¹, Matthew Weston¹, Louise C Mayor¹, James N O'Shea¹

Affiliation

¹ School of Physics and Astronomy and Nottingham Nanotechnology and Nanoscience Centre (NNNC), University of Nottingham, Nottingham NG7 2RD, United Kingdom.

PMID: 24952561
DOI: 10.1063/1.4882867

Abstract

The interaction of the dye molecule N3 (cis-bis(isothiocyanato)bis(2,2-bipyridyl-4,4'-dicarbo-xylato)-ruthenium(II)) with the ultra-thin oxide layer on a AlNi(110) substrate, has been studied using synchrotron radiation based photoelectron spectroscopy, resonant photoemission spectroscopy, and near edge X-ray absorption fine structure spectroscopy. Calibrated X-ray absorption and valence band spectra of the monolayer and multilayer coverages reveal that charge transfer is possible from the molecule to the AlNi(110) substrate via tunnelling through the ultra-thin oxide layer and into the conduction band edge of the substrate. This charge transfer mechanism is possible from the LUMO+2 and 3 in the excited state but not from the LUMO, therefore enabling core-hole clock analysis, which gives an upper limit of 6.0 ± 2.5 fs for the transfer time. This indicates that ultra-thin oxide layers are a viable material for use in dye-sensitized solar cells, which may lead to reduced recombination effects and improved efficiencies of future devices.