Solution-processed organic crystals written directly with a rollerball pen for field-effect transistors

To deposit organic semiconducting crystals from solution, we propose the use of a rollerball pen as a simple and promising tool. These organic crystal grains of dioctylbenzothienobenzothiophene measured several hundred micrometers. The fabricated OFETs exhibited good device performance with a field-effect mobility (mu(FET)) of 0.7 cm(2)/Vs and an on-off ratio of more than 10(7). Simulation results reveal that the flow behavior of solution from the pen refill tube to the substrate intrinsically enhances the formation of large organic crystals. (C) 2014 Elsevier B.V. All rights reserved.