Flexible H2S sensor based on gold modified polycarbazole films

We present the formation of polycarbazole (PCz) films at air–water interface by measurement of pressure-area isotherm and Brewster angle microscopy. The results suggest that PCz forms a very stable Langmuir multilayer with liquid expanded character. PCz films were deposited on flexible bi-axially oriented polyethylene terephthalate (BOPET) substrate by Langmuir–Blodgett technique. X-ray photoelectron spectroscopy results suggest that grown films are poorly doped (∼12%). These films exhibit chemi-resistive response towards ppm level exposure of H2S and NH3 gases at room temperature. The typical response times of these sensors at 10 ppm exposure of H2S and NH3 respectively are 3.44 min and 40 s. Modification of PCz films with Au (Au-PCz) resulted in a remarkable increase in the sensor response and selectivity towards H2S over NH3. Possible mechanism of response/selectivity improvement of Au-PCz towards H2S has been discussed.