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Reversing the Humidity Response of MoS2- And WS2-Based Sensors Using Transition-Metal Salts

TitleReversing the Humidity Response of MoS2- And WS2-Based Sensors Using Transition-Metal Salts
Publication TypeArticolo su Rivista peer-reviewed
Year of Publication2021
AuthorsXiao, P., Mencarelli D., Chavez-Angel E., Joseph C.H., Cataldo Antonino, Pierantoni L., Torres C.M. Sotomayor, and Sledzinska M.
JournalACS Applied Materials and Interfaces
KeywordsCharge trapping, Chemical stability, Chlorine compounds, Copper compounds, Electrical response, High surface-to-volume ratio, Humidity sensors, Layered semiconductors, Lumped element model, Molybdenum compounds, Sensing applications, Silver compounds, Time-dependent performance, Transition metal dichalcogenides, Transition metal salts, Transition metals, Tungsten compounds, Two-dimensional materials

Two-dimensional materials, such as transition-metal dichalcogenides (TMDs), are attractive candidates for sensing applications due to their high surface-to-volume ratio, chemically active edges, and good electrical properties. However, their electrical response to humidity is still under debate and experimental reports remain inconclusive. For instance, in different studies, the impedance of MoS2-based sensors has been found to either decrease or increase with increasing humidity, compromising the use of MoS2 for humidity sensing. In this work, we focus on understanding the interaction between water and TMDs. We fabricated and studied humidity sensors based on MoS2 and WS2 coated with copper chloride and silver nitrate. The devices exhibited high chemical stability and excellent humidity sensing performance in relative humidity between 4 and 80%, with response and recovery times of 2 and 40 s, respectively. We have systematically investigated the humidity response of the materials as a function of the type and amount of induced metal salt and observed the reverse action of sensing mechanisms. This phenomenon is explained based on a detailed structural analysis of the samples considering the Grotthuss mechanism in the presence of charge trapping, which was represented by an appropriate lumped-element model. Our findings open up a possibility to tune the electrical response in a facile manner and without compromising the high performance of the sensor. They offer an insight into the time-dependent performance and aging of the TMD-based sensing devices. © 2021 American Chemical Society.


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Citation KeyXiao2021