title: Experimental observation of sub-femtosecond charge transfer in a model water splitting dye-sensitized solar cell.
abstract: Charge transfer from photoexcited dye molecules to a semiconductor substrate forms the basis of dye sensitized solar cells (DSCs); the overall effectiveness of a DSC device is critically dependent upon the efficiency of this process due to competition with other de-excitation channels. In this paper, we experimentally derive timescales for the charge transfer process in model water splitting DSCs. We studied two organometallic dye complexes adsorbed onto a rutile TiO(2)(110) substrate, the dye molecules were deposited in ultra-high vacuum using electrospray deposition. DFT simulations were used to calculate the spatial distribution of orbitals relevant to the charge transfer process. The core-hole clock implementation of resonant photoemission spectroscopy was used to determine upper limits on charge transfer timescales for previously unoccupied orbitals, which were found to be in the low-femtosecond regime apart from one orbital found to have an upper limit in the sub-femtosecond regime.
authors.affiliation: School of Physics and Astronomy and Nottingham Nanotechnology and Nanoscience Centre (NNNC), University of Nottingham, NG7 2RD, United Kingdom.
authors.forename: Matthew
authors.initials: M
authors.lastname: Weston
authors.forename: Karsten
authors.initials: K
authors.lastname: Handrup
authors.forename: Thomas J
authors.initials: TJ
authors.lastname: Reade
authors.forename: Neil R
authors.initials: NR
authors.lastname: Champness
authors.forename: James N
authors.initials: JN
authors.lastname: O'Shea