A new D-D type conjugated polymer containing a fused selenophene unit for organic field effect transistors

Abstract

Extended π-conjugated system is one of most common strategy to enhance the charge carrier mobility in organic electronics. We synthesized a new conjugated polymer (PDSSTV) with a fused-ring-structure, diseleno[3,2-b:2',3'-d]selenophene (DSS). The optical band gap of PDSSTV was found to be 1.70 eV in both solution and film due to its pre-aggregated state even in solution using UV-Vis absorption spectroscopy. Density functional theory (DFT) analysis revealed a twisted conformation of PDSSTV arising from the large size of Selenium in DSS. Upon thermal annealing at 250℃, the intensity of the out of plane order diffraction peak was greatly increased and the crystalline coherence length was also improved in both (100) lamella d-spacing and (010) π-π stacking directions using GIXD analysis. The charge carrier mobility of PDSSTV was probed by fabricating OFETs with a top-gate/bottom contact (TG/BC) architecture to obtain 2 cm2 V-1 s-1 under relatively low operating voltage of -30 V.