  Full control of excitons in 2D materials is an important step to exploit them
for applications. Straintronics is one method that can be used to effectively
control the movement of excitons. Unfortunately, the effects of non-uniform
strain in 2D materials are not yet well understood theoretically, although
these strain fields can be present in experiments in the form of wrinkles,
bubbles, and folds, or even explicitly applied to 2D materials through
pre-patterned surfaces. The effects of these non-uniform strain fields on
multilayers are even less studied due to the sheer size of these systems. In
the present investigation, we study wrinkles that form in homo- and
heterobilayers of 2D transition metal dichalcogenides using density functional
theory. We show that the non-uniform strain leads to the formation of
interlayer excitons in homobilayers of $ \mathrm WSe_2 $ and to exciton
localization in heterobilayers of $ \mathrm WSe_2$-$ \mathrm MoSe_2$. Our
results also reveal that the spin angular momentum is changed due to the mixing
of in- and out-of-plane states which can explain the brightening of the
formerly dark excitonic states under strain. Our results will pave the way
towards a full understanding of the strain-control of excitons in 2D materials.
