Photochemical control of conductivity of polythiophenes with photochromic moieties

Abstract

The synthesis, optical and electrical properties of azobenzene-substituted polythiophene derivatives at the 3-position are reported: one without flexible spacer (PT0) and the other with a hexamethylene spacer (PT6). Photoirradiation of PT6 at 366 nm caused trans-cis isomerization of the azobenzene moiety and this photochromic reaction induced a change in conductivity of the thin film of PT6: the conductivity was 1.1×10 ^–7 S cm ^–1 before irradiation and 8.3×10 ^–7 S cm ^–1 after photoirradiation. After annealing, the conductivity of the film returned to the initial value. The conductivity of a compound without the azobenzene moiety, α-terthienyl (αT3), showed no change on photoirradiation at 366 nm.