Dresden 2006 – scientific programme
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CPP: Chemische Physik und Polymerphysik
CPP 23: POSTER Functional Organic Thin Films
CPP 23.21: Poster
Thursday, March 30, 2006, 17:00–19:00, P2
Improvement of the ambience stability of field effect transistors based on poly(3-hexylthiophene) by molecular design modification — •Dessislava Sainova1, Silvia Janietz1, Udom Asawapirom1, Lorenz Romaner2, Norbert Koch2, and Antje Vollmer3 — 1Fraunhofer Institute for Applied Polymer Research, Geiselbergstr. 69, 14476 Golm — 2Humboldt-Universität zu Berlin, Institut f. Physik, 12489 Berlin — 3BESSY GmbH, 12489 Berlin
Regioregular poly(3-hexylthiophene) (P3HT) belongs to the most attractive soluble polymers for applications in organic field effect transistors (OFETs). The key feature of P3HT is the self-alignment ability that facilitates the formation of crystalline thin films with well-ordered lamellae of co-facially stacked main chains. This assembly ensures fast charge transport in the layer of the ordered backbones and consequently high field effect mobilities. Nevertheless the successful performance of P3HT in OFETs is hindered by the limited operation under air. Both high field effect mobility and ambience stability are essential for practical application purposes. To achieve this attractive combination of properties we have modified the molecular structure of P3HT by introducing tetrafluorbenzene (TFB) units linked in the main chain. The TFB amount is varied to find an optimum between the processability, the ionization potential (IP) and the transistor performance of the synthesized polymers. As a result have been achieved field effect mobilities of 10-2cm2/Vs and ON/OFF ratios of 104. In addition, the OFET performance is retained after several days of air exposure due to the IP-shift up to 0.3 eV as determined by photoemission investigations.