Low-temperature synthesis of 2D MoS₂ on a plastic substrate for a flexible gas sensor

The efficient synthesis of two-dimensional molybdenum disulfide (2D MoS₂) at low temperatures is essential for use in flexible devices. In this study, 2D MoS₂ was grown directly at a low temperature of 200 °C on both hard (SiO₂) and soft substrates (polyimide (PI)) using chemical vapor deposition (CVD) with Mo(CO)₆ and H₂S. We investigated the effect of the growth temperature and Mo concentration on the layered growth by Raman spectroscopy and microscopy. 2D MoS₂ was grown by using low Mo concentration at a low temperature. Through optical microscopy, Raman spectroscopy, X-ray photoemission spectroscopy, photoluminescence, and transmission electron microscopy measurements, MoS₂ produced by low-temperature CVD was determined to possess a layered structure with good uniformity, stoichiometry, and a controllable number of layers. Furthermore, we demonstrated the realization of a 2D MoS₂-based flexible gas sensor on a PI substrate without any transfer processes, with competitive sensor performance and mechanical durability at room temperature. This fabrication process has potential for burgeoning flexible and wearable nanotechnology applications.