Synthesis and Characterization of a Narrow-Bandgap Polymer Containing Alternating Cyclopentadithiophene and Diketo-Pyrrolo-Pyrrole Units for Solar Cell Applications

We have synthesized a narrow-bandgap conjugated polymer (PCTDPP) containing alternating cyclopentadithiophene (CT) and diketo-pyrrolo-pyrrole (DPP) units by Suzuki coupling. This PCTDPP exhibits a low band gap of 1.31 eV and a broad absorption band from 350 to 1000 nm, which allows it to absorb more available photons from sunlight. A bulk hetero-junction polymer solar cell incorporating PCTDPP and C-70 at a blend ratio of 1:3 exhibited a high short-circuit current of 10.87 mA/cm(2) and a power conversion efficiency of 2.27%. (C) 2010 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 48: 1669-1675,2010