Polymer mask-weakening grain-boundary effect: towards high-performance organic thin-film transistors with mobility closing to 20 cm2 V−1 s−1

Abstract

Grain boundary, which is ubiquitous in thin-film devices, plays a negative role in device performance. High-resolution top-contact electrodes provide an effective approach to reduce the channel length for weakening the grain boundary effect in the conducting channel. In this study, polystyrene-based shadow masks are fabricated to produce top-contact electrodes with a channel length of 5 μm. With the aid of these high-resolution electrodes, the mobility of DPA-based thin-film transistors could be improved up to 19.22 cm² V⁻¹ s⁻¹, which is a new breakthrough for the DPA thin-film transistors. Furthermore, this approach can also be extended to more organic semiconducting systems, e.g., pentacene, copper phthalocyanine (CuPc) and copper-hexadecafluorophthalocyanine (F₁₆CuPc), to optimize their performance to one of the best values compared with previous reports. We believe this technology will provide us a good stage to further process top-contact highly integrated organic circuits.