The effect of photodissociation of confined water on photoemission behaviors of monolayer MoS2

The effects of confined water on the photoluminescence of 2D MoS2 depending on the type of isotope, substrate, and surface termination were investigated. The monolayer MoS2 film showed quenched photoluminescence intensity when exposed to water, whereas it was not observed upon exposure to heavy water. This result is attributed to the overtone vibrational energy transfer between 2D MoS2 and water. Furthermore, the investigation of the photoluminescence in 2D MoS2 depending on the surface characteristics indicated that it can be controlled by the adsorbed water on the substrate. Real-time photoluminescence measurements revealed that the two types of adsorbed water affected the variation in the optical properties and that the orientation of the adsorbed water was also significant for reverting to the intrinsic 2D MoS2 by catalytic photodissociation process through exciton-to-vibronic transfer, facilitated in a confined space. Our results indicate that the substrate surface is crucial for controlling the adsorbed water formed during wet-transfer process. Therefore, this study is effective for applications that utilize large-scale two-dimensional materials.