Tailoring excitonic states of van der Waals bilayers through stacking configuration, band alignment and valley-spin

Understand

Excitons in monolayer semiconductors have large optical transition dipole for strong coupling with light field.

• Interlayer excitons in heterobilayers, with layer separation of electron and hole components, feature large electric dipole that enables strong coupling with electric field and exciton-exciton interaction, at the cost that the optical dipole is substantially quenched (by several orders of magnitude).
• In this letter, we demonstrate the ability to create a new class of excitons in transition metal dichalcogenide (TMD) hetero- and homo-bilayers that combines the advantages of monolayer- and interlayer-excitons, i.e.
• featuring both large optical dipole and large electric dipole.