Poly(3-hexylthiophene)- block -poly(pyridinium phenylene)s: Block Polymers of p- and n-Type Semiconductors

Conjugated cryst.-cryst. donor-acceptor-donor block copolymer semiconductors, with regioregular poly(3-hexylthiophene) as a donor (p-type) block and poly(pyridinium phenylene) as an acceptor (n-type) block within the backbone, were produced by sequential Grignard metathesis synthesis of poly(3-hexylthiophene), a Yamamoto-type cross-coupling polymn.-cyclization sequence. These conjugated block copolymers are sol. in org. solvents and display broad optical absorption bands extending close to the near-IR region. They show reversible ambipolar redox properties with high electron affinities of 3.8-4.0 eV as well as useful ionization potentials of 5.1 eV that are characteristic of the resp. blocks. Block copolymers from p- and n-type org. semiconductors are of interest for the formation of nanostructured bulk heterojunctions in photovoltaic devices. [on SciFinder(R)]