Synthesis and characterization of porphyrin-based D-π-A conjugated polymers for polymer solar cells

Two novel porphyrin-based D-A conjugated copolymers, PFTTQP and PBDTTTQP, consisting of accepting quinoxalino[2,3-b]porphyrin unit and donating fluorene or benzo[1,2-b:4,5-b]dithiophene unit, were synthesized, respectively via a Pd-catalyzed Stille-coupling method. The quinoxalino[2,3-b]porphyrin, an edge-fused porphyrin monomer, was used as a building block of D-A copolymers, rather than the simple porphyrin unit in conventional porphyrin-based photovoltaic polymers reported in literature, to enhance the coplanarity and to extend the -conjugated system of polymer main chains, and consequently to facilitate the intramolecular charge transfer (ICT). The thermal stability, optical, and electrochemical properties as well as the photovoltaic characteristics of the two polymers were systematically investigated. Both the polymers showed high hole mobility, reaching 4.3 x 104 cm2 V1 s1 for PFTTQP and 2.0 x 104 cm2 V1 s1 for PBDTTTQP. Polymer solar cells (PSCs) made from PFTTQP and PBDTTTQP demonstrated power conversion efficiencies (PCEs) of 2.39% and 1.53%, both of which are among the highest PCE values in the PSCs based on porphyrin-based conjugated polymers. (c) 2013 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2013, 51, 2243-2251