Electronic Structure of Self-Assembled Monolayers on ZnO Surfaces
2011 (English)Conference paper, Poster (Other academic)
Controlling the electronic properties at the interface between organic and inorganic materials is an issue of high interest since it is known to strongly affect the charge injection and the overall efficiency of opto-electronic devices. Self-assembled monolayers (SAMs) can be used to change the electronic properties of the underlying inorganic material and optimize the charge injection occurring at the interface. In this context, we aim here at a fundamental understanding of the electronic processes taking place when SAMs are deposited on ZnO. In particular, our theoretical investigations focus on the origin of the shift in the conduction band upon addition of SAMs on the ZnO surface. Calculations were performed within the framework of density functional theory (DFT) using periodic boundary conditions. The SAMs investigated here are 4-tertbutylpyridine (SAM1) and benzoic acid (SAM2), this latter with three different terminations. We show how the conduction band varies in the presence of SAMs on both polar and non-polar ZnO surfaces, in comparison to the bare surface. We find a shift in opposite direction for SAM1 and SAM2 for both surface orientations. A charge density analysis has been performed to identify the role of the surface orientation, bond dipole and dipole moment of the individual molecules in the observed effect. These theoretical observations have been confronted to preliminary experimental data for ZnO nano-particles with and without SAMs.
Place, publisher, year, edition, pages
Materials Chemistry Theoretical Chemistry
IdentifiersURN: urn:nbn:se:uu:diva-244423OAI: oai:DiVA.org:uu-244423DiVA: diva2:788817
E-MRS. Strasbourg, France.