A croconic acid-derived narrow band gap conjugated microporous polymer.

Croconic acid, a novel highly electron-deficient building block, was introduced into a conjugated microporous polymer (CTPA). The CMP possesses strong donor-acceptor interactions, which resulted in near-IR absorption (red edge ∼1350 nm), a narrow bandgap (<1 eV) and high electrical conductivity upon doping (0.1 S m -1 ). Compared to the squaric acid congener (STPA), CTPA showed superior optical, electronic and electrical properties.