Moiré superlattices that are located within van der Waals (vdW) heterostructures can trap long-lived interlayer excitons to form ordered quantum dot arrays, paving the way for unprecedented optoelectronic and quantum information applications. Excitons are an electrically neutral quasiparticle that can transport energy without transporting net electric charge. They form when a material absorbs a photon of higher energy than its bandgap and the concept can be represented as the bound state of an electron and an electron hole that are attracted to each other by an electrostatic Coulomb force. In a new report now published on Science Advances, Hongli Guo and a team of scientists in the department of physics and astronomy at the California State University, Northridge, U.S., performed first-principles simulations to shed light on moiré excitons in twisted molybdenum disulfide/ tungsten disulfide (MoS2/WS2 ) heterostructures. The team showed direct evidence of localized interlayer moiré excitons in vdW heterostructures and mapped out the interlayer and intralayer moiré potentials based on energy gaps. They noted nearly flat valence bands in the heterostructures while exploring how the vertical field could be tuned to control the position, polarity, emission energy and hybridization strength of the moiré excitons. The scientists then predicted that the alternating electric fields could control the dipole moments of hybridized moiré excitons, while suppressing their diffusion in moiré lattices.
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Source: Phys.org