Azobenzenes and dithiocarbamates in molecular film devices

The “top-down” approach to improve the performance of small electronic devices is becoming more and more challenging due to economic and engineering restrictions. Thus, researchers seek for alternatives towards efficient, smaller and faster devices. The “bottom-up” method, in which molecules or molecular films implement electronic functionalities, is an outstanding challenge for scientists. The functionalization of metals with molecular films changes the metals’ characteristics and thus the tuning of device properties is possible. The fundamental research of exploring functionalized surfaces is the driving force of this PhD-work. In particular, the focus will be set on the electronic communication between two interfaces which have to be considered when gearing towards applications such as organic light-emitting diodes and organic field?effect transistors. The investigations on appropriate metal-molecule and molecule-semiconductor interfaces are crucial to improve the charge transport of a molecular thin film device. The exploration of the metal’s work function is of particular interest and is the main aspect addressed in this work. However, the modulation of the molecular backbone to tune the crystallinity of the self?assembled monolayer and thus the electronic properties of the metal is also investigated within this project.
The design, synthesis and characterization of molecular structures bearing azobenzenes and dithiocarbamates, which are appealing functional units, is presented in this work. Subsequently, the self-assembled monolayers of these structures are prepared and the interdependence of the self-assembled monolayers and the substrate electrodes is investigated. These studies are performed in a close collaboration with the research groups of Prof. P. Samorì, Prof. Dr. B. Doudin, Prof. C. Wöll and Prof. M. A. Rampi and with Dr. F. von Wrochem and Dr. W. Ford from the Material Science Laboratory of SONY Deutschland GmbH. Within this research activity the main aim is to obtain a deeper understanding of the correlation between the structural architecture of molecular films and the overall device’s electronic performance.