Christian Westermeier

German

Organic thin films of small aromatic molecules exhibit semiconductor properties which make them promising candidates for innovative electronic devices, such as organic field-effect transistors (OFET), photovoltaics (OPV) or light emitting diodes (OLED). We employ thermal deposition techniques in ultra high vacuum, the most controlled way of producing thin films. The morphology of these thin films such as grain orientation, grain size distribution and dislocation densities are supposed to influence the electronic properties substantially. Thus, a main focus of our work is to correlate structural aspects with electronic transport properties.

The primary objective of my PhD project is local characterization of micro- and nanostructured p- and n-conducting organic layers by imaging with a focused laser beam. For this purpose, we use local illumination by laser scanning techniques with submicron resolution to measure the spatially resolved photoresponse, reflection, luminescence and micro-Raman scattering. These local investigations are performed on thin films and heterojunctions arising from self organization of laterally processed organic materials in a field-effect transistor geometry. The gained results help to understand the crucial relation between the real structure and optoelectronic properties of organic thin films and their emerging interfaces.