Ultrafast Electron Injection to Photo-Excited Organic Absorbates
Gian Paolo Brivio a, Dean Cvetko b, Gregor Kladnik b, Albano Cossaro b, Alberto Morgante b, Guido Fratesi c, Latha Venkataraman d
a University of Milano-Bicocca, via Cozzi 55, Milano, Italy
b CNR-IOM, Trieste, Italy
c Università di Milano, Milano, Italy
d Columbia University, US, Broadway, 3000, New York, United States
Materials for Sustainable Development Conference (MATSUS)
Proceedings of September Meeting 2016 (NFM16)
Berlin, Germany, 2016 September 5th - 13th
Organizers: Marin Alexe, Enrique Cánovas, Celso de Mello Donega, Ivan Infante, Thomas Kirchartz, Maksym Kovalenko, Federico Rosei, Lukas Schmidt-Mende, Laurens Siebbeles, Peter Strasser, Teodor K Todorov, Roel van de Krol and Ulrike Woggon
Oral, Gian Paolo Brivio, presentation 425
Publication date: 14th June 2016

Charge transfer rates at metal/organic interfaces affect the efficiencies of devices for organicelectronics and photovoltaics. A quantitative study of electron transfer rates, which occur 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 the 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. By density functional theory calculations, we show that the alignment of molecular levels relative to the metal Fermi level is modified when a core-hole is created on the molecule, allowing the lowest unoccupied molecular orbital to fall partially below the metal Fermi level. Within a description derived by electron transport in which a semi-infinite substrate is taken into account we 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.



© FUNDACIO DE LA COMUNITAT VALENCIANA SCITO
We use our own and third party cookies for analysing and measuring usage of our website to improve our services. If you continue browsing, we consider accepting its use. You can check our Cookies Policy in which you will also find how to configure your web browser for the use of cookies. More info