Organic single crystal transistor characteristics of single-crystal phase pentacene grown by ionic liquid-assisted vacuum deposition

Organic transistor characteristics of single-crystal phase pentacene were investigated. Ionic liquids (ILs) were used as not only a gate dielectric material in the transistors but also a crystallization solvent in vacuum deposition of pentacene. The crystal sizes reached 200 mu m and their surface exhibits a molecularly step-and-terrace structure. There was no sign of IL molecules inside the crystal, and the impurity level of 6,13-pentacenequinone was also reduced. The average value of the field-effect mobility was not so inferior to those for the conventional pentacene single crystals, and the highest value exceeded 5 cm(2)/Vs, with the on/off current ratio of 10(4). (C) 2012 American Institute of Physics. [http://dx.doi.org/10.1063/1.4747148]