Conjugated polysquaraines synthesized by polycondensation: Physical, optical, and charge transport properties

At present, most of the reported conjugated polysquaraines are limited to the pyrrole and indolenine derivatives. Regarding such monotonous structural design, we herein develop two novel main-chain p-π conjugated polysquaraines through a facile metal-free polycondensation from anilinosquaraines. The success of our polymerization opens the diversity in the structural design of conjugated polysquaraines since the targeted polymers can be simply tailored through modifying the triphenylamine-based monomers. In this work, the fluorene and carbazole groups are employed as the bridging units to prepare P1 and P2, respectively. Both polymers exhibit clear p-type charge transport behaviour based on organic field-effect transistors, and particularly the fluorene-bridged P1 can yield an average hole mobility of 1.2×10−3 cm2 V−1 s−1, representing one of the best polysquaraines that have been reported so far. This study presents an effective method to prepare efficient polysquaraine-based semiconductors.