Room temperature operated ammonia gas sensor using polycarbazole Langmuir–Blodgett film

Langmuir–Blodgett (LB) and spin casting techniques were utilized for preparing thin films of pure polycarbazole, and polycarbazole mixed with octadecylamine (ODA). These films were characterized by using UV–vis absorbance spectroscopy and cyclic voltammetry (CV). Sensitivity of these ultra-thin films to ammonia was studied by measuring changes in electrical resistance. It was found that pure polycarbazole LB films have higher sensitivity, as well as faster response and recovery to ammonia as against ODA mixed polycarbazole LB films, electropolymerized carbazole films and spin cast polycarbazole films. The sensor prepared from pure polycarbaole LB films has been found to show reproducible response in the concentration range of 0–5000 ppm. The sensors are operable at room temperature.