Enhanced NO2 selectivity of hybrid poly(3-hexylthiophene): ZnO-nanowire thin films

Abstract

Sensing characteristics of the drop-cast thin films of poly(3-hexylthiophene) (P3HT), ZnO nanowires, and P3HT:ZnO-nanowire hybrids with different compositions have been studied for various gases, namely, $\mathrm{N}{\mathrm{O}}_2$ , ${\mathrm{H}}_2\mathrm{S}$ , $\mathrm{N}{\mathrm{H}}_3$ , $\mathrm{C}{\mathrm{H}}_4$ , and CO. At room temperature, pure P3HT and ZnO-nanowire films were highly sensitive to $\mathrm{N}{\mathrm{O}}_2$ and ${\mathrm{H}}_2\mathrm{S}$ , moderately sensitive to CO, and nearly insensitive to $\mathrm{N}{\mathrm{H}}_3$ and $\mathrm{C}{\mathrm{H}}_4$ . P3HT:ZnO-nanowire hybrid films, with increasing ZnO-nanowire content, exhibited gradual enhancement in $\mathrm{N}{\mathrm{O}}_2$ sensitivity, while reducing sensitivity for ${\mathrm{H}}_2\mathrm{S}$ . P3HT:ZnO-nanowire (1:1 ratio by weight) films were found to be highly selective for $\mathrm{N}{\mathrm{O}}_2$ . Plausible mechanisms explaining the enhanced $\mathrm{N}{\mathrm{O}}_2$ selectivity by hybrid films are discussed.