Poly(2,3-dihexylthieno[3,4-b]pyrazine). A new processable low band-gap polyheterocycle

A new soluble, low band-gap polymer, poly(2,3-dihexylthieno[3,4-b]pyrazine)2b, which is dark blue–black in the neutral state and which becomes transparent light yellow when doped has been prepared; it has a doped film conductivity of 3.6 × 10–2 S cm–1 and a band-gap (film) of ca. 0.95 eV making it one of the lowest band-gap polymers prepared to date.