Organo-Compatible, Single-Step Interface Engineering for All-Inkjet-Printed Transparent Organic Thin-Film Transistors on Flexible Platforms

초록

Transparent organic thin-film transistors (OTFTs) on flexible platforms have attracted much attention as key driving components in next-generation transparent flexible electronics [1-2]. In this regard, an organo-compatible interface engineering between the transparent organic layers is necessary because the enhanced interfacial properties can be a key pathway for realizing high-performance transparent OTFTs, which determine the crystallinity of π-conjugated semiconductors and carrier injection from the source/drain (S/D) electrodes to semiconductor layers [3]. Especially, effective surface treatments on transparent conductive polymer electrodes are highly desired to allow uniformly deposited solution-processed organic semiconductor near S/D contacts which are compatible with a fast inkjet printing process and flexible platforms. In this paper, to the best of our knowledge, we firstly report an organo-compatible single-step and effective interface engineering conducted onto both transparent poly(3,4-ethylenedioxythiophene):polystyrene sulfonate (PEDOT:PSS) electrodes and an organic gate dielectric without any preliminary treatment to realize high-performance transparent OTFTs and inverters with all organic layers, which are fabricated by a low-cost inkjet printing method on flexible plastic substrates. The inkjet-printed dimethylchlorosilane-terminated polystyrene (PS) (PS?Si(CH3)2Cl) delivered better carrier injection properties and crystallinity of the semiconductor layer, and minimized defect sites on the gate dielectric layer, exhibiting better electrical performance of the all-inkjet-printed transparent OTFTs and inverters. On the benefit of the chemically coupled PS interlayer, transparent OTFTs on a flexible plastic substrate showed much better electrical characteristics (μFET ~ 0.27 cm2/Vs, Vth = 2.42 V, SS = 1.16 V/dec, and Ion/Ioff > 106), in comparison to the no interlayer system showing severely degraded values (μFET < 0.02 cm2/Vs, Vth = 4.41 V, SS =