Optical Properties of Twisted Bilayer Transition Metal Dichalcogenides from the Bethe-Salpeter Equation

We present results for optical properties of twisted transition metal dichalcogenide homo- and heterobilayers, such as absorption spectra and exciton binding energies, and discuss their dependence on the chemical composition of the constituent monolayers and the twist angle between them. For this, we solve the Bethe-Salpeter equation based on wavefunctions and energies from tight-binding calculations that include up to sixth nearest neighbour hoppings. The screened electron-hole interaction is described by a Keldysh potential.