Graphene Nanoribbons from Tetraphenylethene-Based Polymeric Precursor: Chemical Synthesis and Application in Thin-Film Field-Effect Transistor

Graphene nanoribbons (GNRs) with a non-zero bandgap are regarded as a promising candidate for the fabrication of electronic devices. In this study, large-scale solution synthesis of narrow GNRs was firstly achieved by the intramolecular cyclodehydrogenation of kinked tetraphenylethene (TPE) polymer precursors prepared by A2B2-type Suzuki-Miyaura polymerization. After the cyclization reaction, the nanoribbons have a better conjugation than the twisted polymer precursor, resulting in obvious red shift in UV/vis absorption and photoluminescence (PL) spectra. The efficient formation of conjugated nanoribbons was also investigated by Raman, FTIR spectroscopy, and microscopic studies. Furthermore, such structurally well-defined GNRs have been successfully developed for top-gated field-effect transistor (FET) by directly solution processing. The AFM images show that the prepared-GNRs thin films form crystalline fibrillar intercalating networks, which can effectively facilitate the charge transport. These FET devices with ion-gel gate dielectrics exhibit low-voltage operation (<5 V) with excellent mobility up to 0.41 cm2·V−1·s−1 and an on-off ratio of 3×104, thus opening up new opportunities for flexible GNRs-based electronic devices.