Abstract

A most appealing feature of the development of (opto-) electronic devices based on conjugated organic materials is the highly visible link between fundamental research and technological advances. Improved understanding of organic material properties can often instantly be implemented in novel device architectures, which results in a rapid progress of performance and functionality of devices. Interfaces between dissimilar materials – organic/organic and organic/inorganic – are inherent in organic electronic devices. It has been recognized that these interfaces are a key for device function and efficiency. Photoelectron spectroscopy is a key tool for investigating the energy levels at such contacts. However, complementary experimental methods (e.g., scanning tunneling microscopy, x-ray absorption spectroscopy, x-ray standing waves) have to be used in conjunction with theoretical modeling in order to obtain a comprehensive understanding of elementary physico-chemical interfacial phenomena. Prototypical examples will be presented that show how the complex interplay of molecular orientation, molecule-substrate charge transfer, and molecular conformation dependent dipoles controls the energy level alignment at molecule/electrode contacts.