Humidity sensitive properties and sensing mechanism of π-conjugated polymer p-diethynylbenzene-co-propargyl alcohol

A novel thin film resistive humidity sensor based on soluble FeCl3-doped copolymer of p-diethynylbenzene with propargyl alcohol (p-diethynylbenzene-co-propargyl alcohol, DEB-co-OHP) was prepared. Its humidity sensitive properties were investigated by electrochemical methods (complex impedance spectra, chronoamperometric and voltammetric measurements), and sensing mechanism presented. The impedance of the sensor changed from 107 to 104 Ω in the range of 33–95% relative humidity (RH), showing high sensitivity. Comparison of steady-state current–RH plots of film with and without DEB-co-OHP indicated that conjugated polymer plays a dominant role in the realization of conductivity change with humidity.