Exciting progress has been made recently regarding organic field-effect transistors (OFETs) owing to significant efforts devoted to the material design of semiconducting conjugated small molecules and polymers. However, the development… Click to show full abstract
Exciting progress has been made recently regarding organic field-effect transistors (OFETs) owing to significant efforts devoted to the material design of semiconducting conjugated small molecules and polymers. However, the development of ambipolar or n-type OFETs lags behind that of p-type devices. Here, we propose a new strategy for the design of ambipolar polymers based on acceptors (A) of diazines (pyridazine or pyrazine) in a “moderate A-weak A (mA-wA)” architecture by integrating intrachain noncovalent interactions to rationally engineer the electronic structure, molecular planarity and backbone curvature of the conjugated copolymers. Thus designed mA-wA polymers with intrachain N⋯S interactions exhibit both high-lying HOMO and low-lying LUMO energy levels for ambipolar charge transport and good planarity with a linear backbone for high and balanced hole and electron mobilities up to 0.39 and 0.30 cm2 V−1 s−1, respectively. Furthermore, the flexible OFETs fabricated on polyethylene terephthalate substrates show high mobilities of 0.26 and 0.32 cm2 V−1 s−1 for holes and electrons, respectively. This design strategy with the newly discovered diazine acceptors to invoke both mA-wA and NCI effects in conjugated polymers for backbone engineering may be applicable to other systems, representing an advanced concept for the construction of high-performance ambipolar polymers.
               
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