Polyimide-based gate dielectrics for high-performance organic thin film transistors

Abstract

In this work, polyimide-based novel polymer dielectric materials, containing a cross-linkable olefin group and a long alkyl chain with biphenyl, were designed and synthesized by a mild chemical synthesis method to avoid thermal imidization so that they can be widely utilized. The two novel polyimide materials show good thermal stability, pinhole-free dense film morphologies, low leakage current densities (<2 × 10⁻⁷ A cm⁻² at 150 MV m⁻¹) and small dielectric loss values (<0.02, 10³ to 10⁷ Hz), which provides excellent insulating properties. In order to explore their possibility as dielectric layers, the bottom-gate top-contact para-hexaphenyl (p-6P)/vanadyl-phthalocyanine (VOPc) OTFTs with these two polyimide polymer thin films as the dielectric layers exhibit excellent device performance with a high charge carrier mobility of 1.11 and 1.23 cm² V⁻¹ s⁻¹, current on/off ratio >5 × 10⁵, and relatively low threshold voltage (10 and 3.6 V, respectively).