Selenophene-Flanked Diketopyrrolopyrrole Based Conjugated Polymers for Ambipolar Field-Effect Transistors

The Summary of main observation and conclusion The development of selenophene-flanked DPP (SeDPP) based copolymers, especially for the ambipolar ones, lags behind other aromatic group flanked DPP-based polymers. Herein, we report two new ambipolar SeDPP-based conjugated polymers. One is the alternating polymerPSeDPPFTwith normal SeDPP and 3,4-difluorothiophene units. The other isPSeFDFT, in which the electron acceptor unit is replaced by a new SeDPP derivative, referred as to half-fused SeDPP. The more planar structure of half-fused SeDPP endows the backbone ofPSeFDFTwith good rigidity and planarity. Both polymers exhibit ambipolar transporting properties in air. ThePSeFDFTbased field-effect transistors (FETs) display higher and more balanced ambipolar properties with mu(ave)(h) of 0.27 cm(2).V-1.s(-1), mu(ave)(e) of 0.18 cm(2).V-1.s(-1), and mu(ave)(h)/mu(ave)(e) of 1.5 than those ofPSeDPPFT(mu(ave)(h)= 0.11 cm(2).V-1.s(-1) ,mu(ave)(e)= 0.042 cm(2).V-1.s(-1), and mu(h)/mu(e)= 2.6). This is attributed to the more planar structure, lower LUMO level, higher HOMO level, and better interchain packing orientations ofPSeFDFTby comparing withPSeDPPFT. Therefore, a new molecular design strategy to modulate the hole and electron transporting properties is proposed for conjugated D-A polymers.