Preface: phys. stat. sol. (b) 245/5

Abstract

AbstractOrganic materials exhibit fascinating transport phenomena at various length scales. For instance, macroscopic organic single crystals have an electron and hole mobility comparable with that of amorphous silicon, indicating that these novel materials are possible substitutes in technical applications. Despite many experimental and theoretical efforts, there remains still a lack of knowledge regarding basic transport parameters. For example the charge transport mechanism is highly dependent on the interplay between packing, the effective bandwidth and the nature of electron–phonon coupling and may vary from band‐like behavior to thermally activated hopping.On the other hand, charge transport across single molecules bridged between metallic leads shows complex conductance characteristics depending on the contact to the leads, molecule composition, and conformation. From both an experimental and theoretical point of view, these samples define benchmark systems for the analysis of principle contributions to the charge carrier transport.In‐between these limiting cases, organic thin films have established an emerging field of devices such as light emitting diodes, thin film transistors or photovoltaic cells. Due to controlled preparation of layered molecular structures with defined properties, some of these devices have already successfully entered the market and supply further motivation to study the underlying transport processes. Here the understanding of the impact of disorder on charge transport parameters is of crucial importance.All the above mentioned aspects have prompted us to organize an international summer school on ‘Charge Transport in Organic Materials’ which was held in September 2007 at the Physikzentrum Bad Honnef. The challenge of this school – with 19 invited key speakers and more than 140 students the biggest school ever organized in Bad Honnef – was to provide a bridge between the communities working on the transport phenomena of the various molecular systems.The following 15 articles emanate from this event and address many of the various aspects of transport in single crystals, films, and individual molecules, backed‐up by the corresponding theoretical approaches. The equal numbers of contributions indicate the exceptional balance between experiment and theory. All contributions are written by experts in the field and provide an up‐to‐date and in depth overview on the respective subjects.April 2008