Efficient passivation of monolayer MoS by epitaxially grown 2D organic crystals.

Monolayer molybdenum disulfide (MoS) is considered to be a promising candidate for field-effect transistors and photodetectors due to its direct bandgap and atomically thin properties. However, the MoS devices are impeded by the intrinsic surface defects and environmental adsorption such as HO and O. Here, we demonstrated a highly ordered, ultrathin (<5 nm) and scalable N,N'-ditridecylperylene-3,4,9,10-tetracarboxylic diimide (PTCDI-C13) passivation layer that can be epitaxially grown on MoS. The van der Waals interface between PTCDI-C13 and MoS can efficiently reduce the surface traps and isolate MoS from ambient. As a result, the passivated devices exhibit huge improvement in both carrier mobility (from 0.5 to 8.3 cm/(V s)) and sub-threshold swing (from 16.7 to 1.6 V/dec). Also, the photodetector made on MoS after passivation has a much faster response speed (from 3 s to 10 ms) without significant sacrifice of the responsivity. Our method provides a facile approach to realize high-performance two-dimensional electronic and optoelectronic devices.