Electrical properties of multi-walled carbon nanotubes/PEDOT:PSS nanocomposites thin films under temperature and humidity effects

The effect of temperature and humidity on the electrical properties of thin films based on multi-walled carbon nanotubes (MWCNTs) dispersed in sodium dodecylbenzene sulfonate (SDBS) and mixed with poly (3,4-ethylene dioxythiophene)–poly (4-styrenesulfonate) (PEDOT:PSS) were investigated systematically. The change in DC-resistivity was measured by 4-wire technique as a function of the temperature and the relative humidity (RH). The investigation of temperature influence shows semiconducting behavior in the temperature range from 20 °C to 80 °C. This behavior is due to the tunneling barrier, which is expected to dominate the overall film resistance in this temperature range. Moreover, the investigation of humidity effects at temperatures up to 60 °C shows that the resistivity increases exponentially until 70% RH and then it starts to decrease sharply because of development of water layer on PEDOT:PSS film. This effect plays a minor role at high working temperature e.g. 70 °C. Below the saturation point, the films act as a humidity sensor with high sensitivity around ∼0.07%RH.