A Conjugated Polymer Containing a B ← N Unit for Unipolar n-Type Organic Field-Effect Transistors

Solution-processed organic field-effect transistors (OFETs) have great potential for next-generation plastic electronics. The development of n-type polymer semiconductors still lags far behind that of p-type polymer semiconductors, including material number and device performance. Moreover, the reported high-performance n-type polymer semiconductors are mostly based on amide and imide units. To enrich the family of n-type polymers and promote the development of OFETs, we have proposed using a boron-nitrogen coordination bond (B <- N) to develop n-type polymer semiconductors. In this work, we report a B <- N-containing conjugated polymer, PBN-13, which is an alternating polymer of a double B <- N-bridged bipyridine unit and a 5,6-difluoro-4,7-di(thiophen-2-yl)benzo[c][1,2,5]thiadiazole unit. This polymer exhibits strong aggregation ability in solution and good crystallinity in a thin film, which are very desirable for achieving good electron-transporting properties. The OFET device based on PBN-13 shows unipolar n-type behavior with an electron mobility of 0.19 cm(2) V-1 s(-1). The electron mobility is enhanced similar to 10-fold compared to those of other n-type polymer semiconductors containing a B <- N unit. This study thus not only provides an efficient n-type polymer semiconductor but also proves that the B <- N unit is a promising candidate for the development of n-type polymer materials for OFETs.