New solution processable polymers for organic electronics (Printed Electronics Europe 2005)

Combining high charge carrier mobility and ambient air stability is a major challenge in the design of solution processable organic semiconducting polymers. Thiophene polymers have demonstrated the highest p-type field effect mobility of any solution processed polymer to date. One drawback of this class of polymers however, is that they can possess a relatively low ionisation potential, which in the presence of oxygen, often results in spontaneous p-type doping. As a result, in some transistor device configurations, the transistor properties can change with time, leading to a lower current modulation caused by higher off currents. In this work, we explore strategies to chemically modify the thiophene backbone structure, which leads to changes in both the backbone conformation and microstructure, as well as the electronic energy levels of the molecular orbitals. A series of terthiophene polymers were synthesised, and their physical and electrical properties reported. The effects of changes in molecular structure on transistor performance and air stability are discussed.

 

Maxim Shkunov received his Diploma (M.S.) in Applied Physics and Mathematics from Moscow Institute of Physics and Technology in 1991 and then joined General Physics Institute (Moscow) as a researcher. In 1993 he went to the University of Utah, USA, to work on his Ph.D. in Condensed Matter Physics. In 1999 he moved back to Europe to take on a postdoctoral position at Cavendish Laboratory (University of Cambridge). He is currently a Project Leader at Merck Chemicals in Southampton, UK working with a research team on physical properties of novel organic semiconductors.

Merck is currently developing new semiconducting and dielectric materials and their processing technology required to bring organic electronics into the marketplace. These innovations are based on Merck's existing competencies in self-assembling organic molecules which are designed to have optimal electronic properties for charge transport. Synthesis of these specialty materials is carried out under the high purity conditions demanded by these high performance devices.