Photochemical control of conductivity of polythiophenes with photochromic moieties

The synthesis, optical and electrical properties of azobenzene-substituted polythiophene derivatives at the 3-position are reported: one without flexi ble spacer (PT0) and the other with a hexamethylene spacer (PT6). Photoirra diation of PT6 at 366 nm caused trans-cis isomerization of the azobenzene m oiety and this photochromic reaction induced a change in conductivity of th e thin film of PT6: the conductivity was 1.1x10(-7) S cm(-1) before irradia tion and 8.3x10(-7) S cm(-1) after photoirradiation. After annealing, the c onductivity of the film returned to the initial value. The conductivity of a compound without the azobenzene moiety, alpha-terthienyl (alpha T3), show ed no change on photoirradiation at 366 nm.