Dresden 2009 – wissenschaftliches Programm
Bereiche | Tage | Auswahl | Suche | Downloads | Hilfe
CPP: Fachverband Chemische Physik und Polymerphysik
CPP 33: Organic Photovoltaics II
CPP 33.1: Vortrag
Donnerstag, 26. März 2009, 14:00–14:15, ZEU 222
Interplay between morphology and energy levels in conjugated polymers: A theoretical view — •Georg Heimel1, Ingo Salzmann1, Steffen Duhm2, Jürgen P. Rabe1, and Norbert Koch1 — 1Institut für Physik, Humboldt-Universität zu Berlin, Newtonstr. 15, D-12489, Berlin, Germany — 2Graduate School of Advanced Integration Science, Chiba University, Japan
Conjugated polymers are important constituents of organic electronic devices and it is both the bulk properties and the interfaces, which decisively determine device performance. For example, the preparation conditions are know to crucially impact the thin-film morphology of the prototypical π-conjugated polymer region-regular poly(3-hexylthiophene) and, consequently, also the device characteristics of, e.g., organic solar cells based on this material (rr-P3HT). We present first-principles calculations on highly ordered monolayers of rr-P3HT and a fluorinated derivative with the backbone orientations varying continuosly from face-on to edge-on. Supported by electrostatic modeling, we find that the backbone orientation importantly influences the energy-level positions in these films due to intra-molecular surface dipoles; we find variations of up to 1.5 eV. As a consequence, also the energy-level alignment at ubiquitous inorganic/organic and organic/organic interfaces can be expected to depend critically on thin-film morphology. Our results provide further insight into the structure-property relationship in an important class of materials and imply novel strategies for molecular, polymer, and device design.