Chemical Vapor Sensing with Transition Metal Dichalcogenides via Photoluminescence Modulation

Two-dimensional transition metal dichalcogenides (TMDs) such as MoS₂ and MoSe₂ are promising materials for chemical vapor sensing applications. Their potential includes straightforward fabrication, readily available materials, and good selectivity, sensitivity, and speed of response. Another attractive aspect is that they have been shown to detect chemical vapors and gases in several ways. More commonly, sensors have been fabricated based on the chemiresistive device properties. Here, however we will discuss our recent studies implementing TMD sensors using the optical properties, in particular the photoluminescence (PL) as the core element of the sensor. We examine the PL of MoSe₂ while it is exposed to strong electron donor gases such as triethylamine. There is a fast and significant decrease in the PL upon exposure with PL reduction by as much as 75% during exposure. When the vapor is turned off, the PL quickly recovers indicating fast adsorption/desorption of the analyte. We compare the temporal response and sensitivity of the PL with that of the electrical change in conductivity and analyze the data in terms of possible applications to chemical vapor sensing of chemicals relevant to nerve gas and explosive sensing. This work was supported by core programs at NRL.