Pentacene thin film transistors fabricated by solution process with directional crystal growth

We have fabricated solution-processed pentacene thin film transistor arrays with mobilities as high as 1.0 cm(2)/V s, evaluated at a low drain voltage of -10 V. This is achieved by controlling the growth direction of the pentacene films from solution, and by optimizing conditions for drop casting. Crystal growth of the solution-processed pentacene films is found to proceed in one direction on a tilted substrate. Grazing incidence X-ray diffraction and electron diffraction reveal that the crystal growth azimuth corresponds to the direction along the minor axis of the a-b plane in the unit cell of the pentacene crystal. This directional growth method is extended to solution processing on large glass substrates with an area of 150 x 150 mm(2). thereby yielding transistor arrays with two-dimensional uniformity and high carrier mobility. (C) 2008 Elsevier B.V. All rights reserved.