Synthesis and Characterization of Novel Low-Bandgap Triphenylamine-Based Conjugated Polymers with Main-Chain Donors and Pendent Acceptors for Organic Photovoltaics

Abstract

A series of novel low bandgap triphenylamine based conjugated polymers (PCAZCN PPTZCN and PDTPCN) consisting of different electron rich donor main chains (N alkyl 2 7 carbazole phenothiazine and cyclopentadithinopyrol respectively) as well as cyano and dicyano vinyl electron acceptor pendants were synthesized and developed for poly mer solar cell applications The polymers covered broad absorption spectra of 400-800 nm with narrow optical band gaps ranging 1 66-1 72 eV The highest occupied molecular or bital and lowest unoccupied molecular orbital levels of the polymers measured by cyclic voltammetry were found in the range of -5 12 to -532 V and -345 to -355 eV respectively Under 100 mW/cm(2) of AM 1 5 white light illumination bulk heterojunction photovoltaic devices composing of an active layer of electron donor polymers (PCAZCN PPTZCN and PDTPCN) blended with electron acceptor [6 6] phenyl C(61) butync acid methyl ester or [6 6] phenyl C(71) butyric acid methyl ester (PC(71)BM) in different weight ratios were investigated The photovoltaic device containing donor PCAZCN and acceptor PC(71)BM in 1 2 weight ratio showed the highest power conversion efficiency of 1 28% with V(oc) = 0 81 V J(sc) = 493 mA/cm(2) and fill factor = 32 1% (c) 2010 Wiley Periodicals Inc J Polym Sci Part A Polym Chem 48 5812-5823 2010