Improving the performance of organic thin film transistors formed on a vacuum flash-evaporated acrylate insulator

A systematic investigation has been undertaken, in which thin polymer buffer layers with different ester content have been spin-coated onto a flash-evaporated, cross-linked diacrylate gate-insulator to form bottom-gate, top-contact organic thin-film transistors. The highest device mobilities, similar to 0.65 cm(2)/V s and similar to 1.00 cm(2)/V s for pentacene and dinaphtho[2,3-b:2',3'-f]-thieno[3,2-b]thiophene (DNTT), respectively, were only observed for a combination of large-grain (similar to 1-2 mu m) semiconductor morphology coupled with a non-polar dielectric surface. No correlation was found between semiconductor grain size and dielectric surface chemistry. The threshold voltage of pentacene devices shifted from -10 V to -25 V with decreasing surface ester content, but remained close to 0 V for DNTT. (C) 2013 AIP Publishing LLC.