Issue 32, 2016

Ultrafast electron injection into photo-excited organic molecules

Abstract

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.

Graphical abstract: Ultrafast electron injection into photo-excited organic molecules

Supplementary files

Article information

Article type
Paper
Submitted
13 Jun 2016
Accepted
14 Jul 2016
First published
14 Jul 2016
This article is Open Access
Creative Commons BY-NC license

Phys. Chem. Chem. Phys., 2016,18, 22140-22145

Ultrafast electron injection into photo-excited organic molecules

D. Cvetko, G. Fratesi, G. Kladnik, A. Cossaro, G. P. Brivio, L. Venkataraman and A. Morgante, Phys. Chem. Chem. Phys., 2016, 18, 22140 DOI: 10.1039/C6CP04099C

This article is licensed under a Creative Commons Attribution-NonCommercial 3.0 Unported Licence. You can use material from this article in other publications, without requesting further permission from the RSC, provided that the correct acknowledgement is given and it is not used for commercial purposes.

To request permission to reproduce material from this article in a commercial publication, please go to the Copyright Clearance Center request page.

If you are an author contributing to an RSC publication, you do not need to request permission provided correct acknowledgement is given.

If you are the author of this article, you do not need to request permission to reproduce figures and diagrams provided correct acknowledgement is given. If you want to reproduce the whole article in a third-party commercial publication (excluding your thesis/dissertation for which permission is not required) please go to the Copyright Clearance Center request page.

Read more about how to correctly acknowledge RSC content.

Social activity

Spotlight

Advertisements