Transition from positive to negative electrical resistance response under humidity conditions for PEDOT:PSS-MoS₂ nanocomposite thin films

Here, we report the preparation of PEDOT:PSS-MoS₂ nanocomposite thin films and their electrical resistance response under humidity conditions revealing their promising properties as humidity sensor materials. One of the most interesting features of our samples is the transition from positive to a negative electrical resistance response to humidity conditions with increasing MoS₂ additions. Our confocal Raman imaging studies revealed that the presence of MoS₂ yields a local charge rearrangement in the thiophenyl rings of PEDOT:PSS, in relation to the enhancement of the electrical resistance negative response as observed by impedance spectroscopy analysis. The enhancement on the negative response with increasing MoS₂ additions could be explained through the increment of hole carriers in MoS₂ nanosheets under humidity conditions, thus leading to an enhancement in the electrical transport along the PEDOT:PSS chains.