An efficient interface modification is introduced to improve the performance of polymeric thin film transistors. This efficient interface modification is first achieved by 4-fluorothiophenol(4-FTP) self-assembled monolayers(SAM) to chemically treat the silver source–drain(S/D) contacts while the silicon oxide(SiO2) dielectric interface is further primed by either hexamethyldisilazane(HMDS) or octyltrichlorosilane(OTS-C8). Results show that contact resistance is the dominant factor that limits the field effect mobility of the PTDPPTFT4 transistors. With proper surface modification applied to both the dielectric surface and the bottom contacts, the field effect mobilities of the bottom-gate bottom-contact PTDPPTFT4 transistors were significantly improved from 0.15 cm2·V-1·s-1 to 0.91 cm2·V-1·s-1. This efficient interface modification is introduced to improve the performance of polymeric thin film transistors. This efficient interface modification is first achieved by 4-fluorothiophenol (4-FTP) self-assembled monolayers (SAM) to chemically treat the silver source-drain (S / D) contacts while the silicon oxide (SiO2) dielectric interface is further primed by either hexamethyldisilazane (HMDS) or octyltrichlorosilane (OTS-C8). Results show that contact resistance is the dominant factor that limits the field effect mobility of the PTDPPTFT4 transistors. With proper surface modification applied to both of the dielectric surfaces and the bottom contacts, the field effect mobilities of the bottom-gate bottom-contact PTDPPTFT4 transistors were significantly improved from 0.15 cm2 · V-1 · s-1 to 0.91 cm2 · V-1 · s-1.