In van der Waals (vdW) heterostructures formed by stacking two monolayers of transition metal
dichalcogenides, multiple exciton resonances with highly tunable properties are formed and subject
to both vertical and lateral confinement. We investigate how a unique control knob, the twist
angle between the two monolayers, can be used to control the exciton dynamics. We observe that
the interlayer exciton lifetimes in MoSe2/WSe2 twisted bilayers (TBLs) change by one order of
magnitude when the twist angle is varied from 1
◦ to 3.5◦. Using a low-energy continuum model, we
theoretically separate two leading mechanisms that influence interlayer exciton radiative lifetimes.
The shift to indirect transitions in the momentum space with an increasing twist angle and the
energy modulation from the moir´e potential both have a significant impact on interlayer exciton
lifetimes. We further predict distinct temperature dependence of interlayer exciton lifetimes in TBLs
with different twist angles, which is partially validated by experiments. While many recent studies
have highlighted how the twist angle in a vdW TBL can be used to engineer the ground states
and quantum phases due to many-body interaction, our studies explore its role in controlling the
dynamics of optically excited states, thus, expanding the conceptual applications of “twistronics”.Center for Dynamics and Control of Material