An article entitled, Thieno[3,4‑b]thiophene Acceptors with Alkyl, Aryl, Perﬂuoroalkyl, and Perﬂuorophenyl Pendants for Donor−Acceptor Low Bandgap Polymers was recently published in Macromolecules.
Professors Coughlin and Lahti, along with graduate students Patrick Homyak and Jon Tinkham have recently reported the design, synthesis, and characterization of a series of thieno[3,4-b]thiophene acceptor blocks. Polymerization by direct arylation polymerization afforded novel low bandgap poly(thienothiophene-alt-dithienylbenzodithiophene)(PTB) polymers. The strongly electron withdrawing fluorinated pendants significantly lowered both EHOMO and ELUMO levels and have relatively higher computed ground-to-excited state dipole changes (Δμge). These materials show favorably aligned energy levels relative to conventional fullerene type acceptors, which should allow them to perform well in organic photovoltaic (OPV) applications.