Temperature-dependent ultra-thin polymer layer for low voltage organic thin-film transistors

In this article, a low voltage organic thin-film transistor (OTFT) was accomplished by using a random copolymer, poly(styrene-co-methyl methacrylate) (PS-r-PMMA), as the gate dielectric. The thickness of PS-r-PMMA polymer can be controlled well by thermal process and shows an ultra-thin property after toluene rinse. The thickness of PS-r-PMMA can be controlled in the range of 2–14 nm. By the densely packed copolymer brush, a leakage current as low as 10−9 A/cm2 was obtained. By utilizing this polymer as gate dielectric, pentacene based organic thin-film transistor could be operated at 5 V with 0.1 cm2/V s mobility and 0.27 V/dec subthreshold swing. In addition to good OTFT properties, the coating, annealing and removing sequential process of PS-r-PMMA ensure that this technique is compatible with the large area printing methods such as ink-jet printing and doctor blade coating. The random copolymer dielectric is therefore suitable for OTFT in large area printed flexible electronic applications.