Recent Advances in Molecular Doping of Organic Semiconductors

Organic semiconductors are the key building blocks in the field of organic electronics, which exhibit enormous advantages in low-cost, light-weight, wide variety, solution-processed manufacturing and mechanical flexibility against their inorganic counterparts. As the active component in a broad range of organic devices, including organic field-effect transistors, organic light-emitting diodes, organic solar cells and organic thermoelectrics, there are ubiquitous needs in efficiently and controllably modulating the properties and functionalities of organic semiconductors. Molecular doping, a versatile platform to tune the optoelectrical properties of organic semiconductors, has been one of the central propositions in further development of organic electronics. In this Review, we focus on the recent advances of molecular doping in organic semiconductors, covering both design of dopant molecules and fundamental doping mechanisms. In addition, the up-to-date development in processing techniques and relevant functional applications are also summarized. Finally, the frontier challenges together with future opportunities in this cross-fertilized field are highlighted. We believe this Review will provide more knowledge and insight on how molecular doping plays a critical role in advancing organic electronics for emerging technologies.