▎ 摘　　要

Direct synthesis of graphene without metal catalysts on a dielectric substrate is a major goal in graphene-based electronics and is an increasingly popular nanotechnology alternative to metal oxide semiconductor technology. However, current methods for the synthesis of these graphenes have many limitations, including the use of metal catalyst. Herein, we report a facile approach to the direct synthesis of graphene sheets based on the self-assembled monolayers (SAMs) technique. The new method for metal catalyst-free direct synthesis of a graphene sheet is through a solution-processable, inexpensive, easy, and reproducible cross-linked polythiophene self-assembled monolayer (SAM) that is formed via the [4+ 2] pi cycloaddition reaction of pi-electron conjugated thiophene layer self-assembled on the dielectric silicon dioxide substrate. The bifunctional molecules were carefully designed to create an SAM via silanization of alkoxy silane groups on the SiO2 substrate, and at the other end, a thin cross-linked polythiophene layer via a [4 + 2] re-electron cycloaddition reaction of it-electron conjugated thiophene SAM. By heating the cross-linked polythiophene SAM up to 1000 degrees C under a high vacuum, single-layered or few-layered graphene sheets were successfully prepared on the dielectric silicon oxide substrate. (C) 2015 Elsevier Ltd. All rights reserved.