Heteroaromatic azo-sulfonamide monolayers: isomerisation and photocurrent generation

Trans–cis isomerisation of the azo-sulfonamide derivatives: 4-(N-methyl-N-n-dodecyl)amino-4′-(N-thiazol-2-yl)sulfonamidoazobenzene, 4-(N-methyl-N-n-dodecyl)amino-4′-(N-pyrimidin-2-yl)sulfonamidoazobenzene, and 4-(N-methyl-N-n-dodecyl)amino-4′-[N-(2-methyl)isoxazol-2-yl]sulfonamidoazobenzene and photocurrent generation in Langmuir–Blodgett (LB) films was investigated. The isomerisation took place on illumination with a light beam corresponding to the absorption band. The reverse cis–trans isomerisation proceeded as a thermal relaxation. It was observed that the LB films deposited during illumination of the trough were more effective in this photoreaction. The LB structures deposited onto conductive ITO glass were able to generate photocurrent in a standard three-electrode system. The photocurrent intensity was in linear relationship with bias voltage in the range from 0 to −0.35 V and in best conditions it reached 160 nA cm−2.