Charge transfer rates at metal/organic interfaces affect the efficiencies of devices for organic based electronics and photovoltaics. A quantitative study of electron transfer rates, which take place on the femtosecond timescale, is often difficult, especially since in most systems the molecular adsorption geometry is unknown. Here, we use X-ray resonant photoemission spectroscopy to measure ultrafast charge transfer rates across pyridine/Au(111) interfaces while also controlling the molecular orientation on the metal. We demonstrate that a bi-directional charge transfer across the molecule/metal interface is enabled upon creation of a core-exciton on the molecule with a rate that has a strong dependence on the molecular adsorption angle. Through density functional theory calculations, we show that the alignment of molecular levels relative to the metal Fermi level is dramatically altered when a core-hole is created on the molecule, allowing the lowest unoccupied molecular orbital to fall partially below the metal Fermi level. We also calculate charge transfer rates as a function of molecular adsorption geometry and find a trend that agrees with the experiment. These findings thus give insight into the charge transfer dynamics of a photo-excited molecule on a metal surface.
Cvetko, D., Fratesi, G., Kladnik, G., Cossaro, A., Brivio, G., Venkataraman, L., et al. (2016). Ultrafast electron injection into photo-excited organic molecules. PHYSICAL CHEMISTRY CHEMICAL PHYSICS, 18(32), 22140-22145.
|Citazione:||Cvetko, D., Fratesi, G., Kladnik, G., Cossaro, A., Brivio, G., Venkataraman, L., et al. (2016). Ultrafast electron injection into photo-excited organic molecules. PHYSICAL CHEMISTRY CHEMICAL PHYSICS, 18(32), 22140-22145.|
|Tipo:||Articolo in rivista - Articolo scientifico|
|Carattere della pubblicazione:||Scientifica|
|Presenza di un coautore afferente ad Istituzioni straniere:||Si|
|Titolo:||Ultrafast electron injection into photo-excited organic molecules|
|Autori:||Cvetko, D; Fratesi, G; Kladnik, G; Cossaro, A; Brivio, G; Venkataraman, L; Morgante, A|
|Data di pubblicazione:||2016|
|Rivista:||PHYSICAL CHEMISTRY CHEMICAL PHYSICS|
|Digital Object Identifier (DOI):||http://dx.doi.org/10.1039/c6cp04099c|
|Appare nelle tipologie:||01 - Articolo su rivista|