In conventional organic field-effect transistors (OFETs), the low mobility of carriers in the organic semiconductor layers leads to low device speed, which seriously limits the applicability of the devices for analog and high frequency circuits in high performance applications. In this paper, the source-gated transistor (SGT) concept is introduced for high performance transistors in low mobility organic semiconductors, in which the source comprises a potential barrier to current flow and a gate is used to modulate the electric field at the reverse-biased source barrier and change the current. Compared to the OFET, the OSGT has a much smaller susceptibility to short-channel effects, and can be operated with much higher internal electrical fields giving high drive current and high speed. The numerical simulation results show that the OSGT can be an excellent candidate for designing high performance transistors in low-mobility organic materials for analog and high frequency applications.