Strain-Induced Electronic Structure and Bandgap Transition in Bilayer $\text{MoSe}_{2}$ of AB and AA Stacking Order

The transition-metal dichalcogenides (TMDC) materials have received intensive research interest for strain engineering applications. In this work, we report the biaxial strain
$(\varepsilon)$
-induced electronic structure of AB and AA stacked 2L
$\text{MoSe}_{2}$
using Density functional theory (DFT) calculations. We found that AB stacked 2L
$\mathbf{MoSe}_{2}$
remains its intrinsic indirect bandgap transition
$(\Gamma-\Sigma_{\min})$
within the strain range from -1.8 % to +0.3%. An indirect to direct bandgap crossover is observed in AA stacked 2L
$\text{MoSe}_{2}$
at a practically achievable strain value of -0.1%. The direct bandgap value for AA-stacked
$\mathbf{MoSe}_{2}$
makes it a promising candidate for optoelectronic device applications. For the higher strain (-2%
$< \varepsilon >$
0.5
^%
), both AB and AA stacked 2L
$\text{MoSe}_{2}$
have similar bandgap tunability and transition.