Humidity sensing using vertically oriented arrays of ReS₂ nanosheets deposited on an interdigitated gold electrode

Wereport a novel humidity sensor featuring vertically oriented arrays of ReS₂ nanosheets grown on an interdigitated gold electrode by chemical vapor deposition. The vertical orientation of the nanosheets is important since it maximizes the exposed surface area for water adsorption/desorption. We find that the resistance of the ReS₂ film decreases sensitively with increasing relative humidity, which we attribute to charge transfer from the absorbed H₂O molecules to the n-doped ReS₂ nanosheets. In addition to high sensitivity, the ReS₂ sensors exhibit fast response/recovery time and excellent reversibility with minimal hysteresis. Moreover, our fabrication approach involving the direct (1-step) growth of the ReS₂ films on an interdigitated electrode (without any transfer using wet chemistry or lithography) greatly simplifies the device architecture and has important practical benefits for the low-cost and scalable deployment of such sensor devices.