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HL: Fachverband Halbleiterphysik

HL 13: Focus Session: Structural Ordering and Electronic Transport II (jointly with CPP)

HL 13.5: Invited Talk

Monday, March 26, 2012, 16:15–16:45, ER 270

Band dispersion and localized states in organic solids — Nobuo Ueno¹ and •Norbert Koch² — ¹Graduate School of Advanced Integration Science, Chiba University, Chiba, Japan — ²Institut f. Physik, Humboldt-Universität zu Berlin, Berlin, Germany

Charge transport in solids is inevitably linked with structural properties. Organic molecular materials are characterized by two hierarchical levels of structure, i.e., the structure of an individual molecule and that of the molecular assembly. As a consequence, both affect the organic solid's electron density of states (DOS) and the mechanisms of charge transport. We give an overview of how photoelectron spectroscopy can be used to study the DOS of organic materials ranging from amorphous thin films to single crystals, and how the sample's structure (including defects) is reflected in localized (gap) states or delocalized dispersing bands. The influence of the molecular chemical structure and the dielectric environment on electron-vibron coupling strength will be discussed. We will address the impact of polymorphism and temperature on the band structure of prototypical organic solids, including tetracene, pentacene, and rubrene.