A Novel Approach Toward Low Optical Band Gap Polysquaraines

Abstract
Polycondensation of 2,5-dialkoxydivinylbenzene-bridged bispyrroles and squaric acid resulted in extensively conjugated polymers with strong near-infrared (NIR) absorption around 800−1000 nm, which is a signature of their low band gap (Eg). Conjugated polymers with such a strong NIR absorption are rare. One of the synthesized polysquaraines showed a significantly low Eg of 0.79 eV with an intrinsic conductivity of 5.3 × 10-4 S/cm.