Controlling Exciton Transport in 1D PbI2 - 2D MoSe2 van der Waals Heterostructure

초록

Van der Waals (vdW) heterostructures composed of two-dimensional (2D) semiconducting material stacks have garnered significant attention owing to their unique optoelectronic properties compared with their single constituent counterparts. Especially, heterostructure devices composed of 2D semiconductors of which the interfacial exciton transport is controllable hold great potential in photonic and optoelectronic applications. Here, we report vdW heterostructures made of PbI2 and MoSe2 and demonstrate that the local exciton distribution can be controlled by modulating the vdW interface between them. PbI2 vdW layers are prepared in one-dimensional (1D) morphologies with discrete stacking orientations and transferred onto the 2D MoSe2 layers grown via the chemical vapor deposition (CVD) method. Specifically, the vapor-liquid-solid (VLS) method was employed to grow 1D PbI2 vdW nanostructures in two different layer stacking orientations (i.e., [001] and [010]) and layer stackings (perpendicular vs. parallel to the wire axis). Upon the transfer onto MoSe2, we confirm that the exciton transfer between the two materials is strongly dependent on the interlayer configurations (i.e., layer-to-layer vs. edge-to-layer). Strong exciton binding energy of PbI2 enables the transport of excitons along with the PbI2 domain via waveguide effect and localized radiative recombination according to the interface with the MoSe2 domain. Our results provide important insights into the engineering of vdW heterostructure interfaces and develop a new design rule of ultrathin optoelectronic devices.