Understanding Solvent‐Induced Delamination and Intense Water Adsorption in Janus Transition Metal Dichalcogenides for Enhanced Device Performance

Recently, there has been considerable interest in 2D Janus transition metal dichalcogenides owing to their unique structure that exhibits broken mirror symmetry along the out‐of‐plane direction, which offers fascinating properties that are applicable in various fields. This study investigates the issue of process instability in Janus MoSSe, which is mainly caused by its nonzero net dipole moments. It systematically investigates whether the built‐in dipole moments in Janus MoSSe make it susceptible to delamination by most polar solvents and increase its vulnerability to intense moisture adsorption, which leads to the deterioration of its semiconducting properties. To address these issues, as an example of device applications, field‐effect transistors (FETs) based on a van der Waals heterostructure are devised, where the bottom h‐BN (top h‐BN) insulating material is employed to prevent delamination (adsorption of moisture). The fabricated FETs exhibit improved electron mobility and excellent stability under ambient conditions. Manipulating Janus transition metal dichalcogenides (J‐TMDCs) for advanced device applications is challenging because of their nonzero built‐in dipole moment. The authors research dipole moments in Janus MoSSe, highlighting moisture adsorption and solvent‐induced delamination as detrimental effects. To tackle challenges, a unique all‐van‐der‐Waals structure is developed for Janus MoSSe‐based FETs, leading to successful improvements in their electrical performance through optimized configurations.