Self-Aligned Fabrication Process of Electrode for Organic Thin-Film Transistors on Flexible Substrate Using Photosensitive Self-Assembled Monolayers

Abstract

A new long-wavelength-photosensitive self-assembled-monolayer (SAM) was developed, and a process fabricating alignment-free printable electrodes for flexible organic thin-film transistors (OTFTs) with the SAM was proposed. The SAM was degraded and its wetability was changed from hydrophobic to hydrophilic by irradiating it with UV light (>350 nm). The irradiated areas of SAM became more hydrophilic with tetramethylammonium hydroxide (TMAH) solution, which is a commercially available photoresist developer. Using the SAM and a back substrate exposure technique with TMAH rinsing, we can induce the self-alignment of solution-processed source/drain electrodes with respect to a gate electrode. A 20-µm-gap pattern of PEDOT was successfully formed by spin-coating on a plastic substrate.