Doping of semiconductors,i.e.,accurately modulating the charge carrier type and concentration in a controllable manner,is a key technology foundation for modem electronics and optoelectronics.However,the conventional doping technologies widely utilized in silicon industry,such as ion implantation and thermal diffusion,always fail when applied to two-dimensional (2D) materials with atomically-thin nature.Surface charge transfer doping (SCTD) is emerging as an effective and non-destructive doping technique to provide reliable doping capability for 2D materials,in particular 2D semiconductors.Herein,we summarize the recent advances and developments on the SCTD of 2D semiconductors and its application in electronic and optoelectronic devices.The underlying mechanism of STCD processes on 2D semiconductors is briefly introduced.Its impact on tuning the fundamental properties of various 2D systems is highlighted.We particularly emphasize on the SCTD-enabled high-performance 2D functional devices.Finally,the challenges and opportunities for the future development of SCTD are discussed.