In this study, we report the design and synthesis of two donor-acceptor isoindigo dye-based copolymers, namely PIIVS1 and PIIVS2, in which sr-extended diselenophenylethene building block acts as electron-donating units. The charge transport properties of both copolymers were studied by fabricating field-effect transistors (FETs). The two copolymers-based FETs with electrodes modified by thiol self assembled monolayers (SAMs) showed enhanced mobilities of up to 1.58 cm(2) V-1 s(-1) (average: 1.28 cm(2) V-1 s(-1)), almost two times higher than those achieved in unmodified counterparts. Thereby, a systematical investigation on PIIVS2-based PFETs was performed, indicating contact resistances, contact angles and Au work function all changed in different extents, and more uniform thin film morphologies obtained in thiol-treated PFET devices. The results demonstrate the potential and feasibility of electrodes modification by thiol-based SAMs on improving the device performance of FETs. (C) 2017 Elsevier Ltd. All rights reserved.