Recently, a lot of effort has been focused on improving the performance and exploring the electric properties of graphene. This article presents a summary of chemical doping of graphene aimed at tuning the electronic properties of graphene. p-Type and n-type doping of graphene achieved through surface transfer doping or substitutional doping and their applications based on doping are reviewed. Chemical doping for band gap tuning in graphene is also presented. It will be beneficial to designing high performance electronic devices based on chemically doped graphene.

A novel reducing reagent, Lawesson's reagent (LR), is used to directly reduce graphene oxide (GO) films and single GO sheets. The as-prepared reduced graphene oxide (GOLR) is fully characterized by XPS, Raman, FTIR, ¹³C NMR and XRD. Most of the oxygen-containing groups are efficiently removed by LR and the conjugated graphene networks are restored. Highly conductive GOLR films and sheets are obtained. As a proof of concept, thin film field-effect transistors based on pentacene using patterned GOLR films as electrodes are fabricated and show high performances. Common cotton threads coated with GOLR can be used as flexible connecting wires to illuminate commercial light-emitting diodes. After low temperature annealing, such as 300 °C, higher conductivity and mobility of GOLR are obtained due to the removal of additional oxygen groups and better ordering of graphene sheets.