"Semi-random" multichromophoric rr-P3HT analogues for solar photon harvesting

A family of semi-random donor-acceptor copolymers based on regioregular poly(3-hexylthiophene) (P3HT) are described. A semi-random alkylthiophene-based copolymers, which absorb sunlight due to the randomized incorporation of small amounts of acceptors in the polymer backbone, are introduced. The semi-random structure is defined by a random polymerization that is based on a restricted linkage pattern of the monomers due to regiospecific placement of the reactive functional groups. Red shifts of the absorption peaks when comparing solution spectra to thin film spectra are between 50 and 100 nm, which indicates ordering and planarization of the polymer chains in the solid state. P3HTT-BTD develops semicrystalline features after annealing at 150°C and the interchain packing distance for P3HTT-BTD is calculated as 15.6 Å.