Angle-dependence of interlayer coupling in twisted transition metal dichalcogenide heterobilayers

TL;DR

This study uses first-principles calculations to show how twist angle affects interlayer binding, charge transfer, and electronic properties in MoS2/MoTe2 heterobilayers, revealing a Gaussian dependence of binding energy on twist angle.

Contribution

It introduces a detailed analysis of twist-angle-dependent interlayer interactions and electronic properties in MoS2/MoTe2 heterobilayers, highlighting the geometric and charge transfer effects.

Findings

Interlayer binding decreases with twist angle, following a Gaussian-like function.

Band gap reduces as twist angle increases, contrasting with MoS2 homobilayers.

Significant interlayer charge transfer from MoTe2 to MoS2, weakening with larger twist angles.

Abstract

We reveal by first-principles calculations that the interlayer binding in a twisted MoS2/MoTe2 heterobilayer decreases with increasing twist angle, due to the increase of the interlayer overlapping degree, a geometric quantity describing well the interlayer steric effect. The binding energy is found to be a Gaussian-like function of twist angle. The resistance to rotation, an analogue to the interlayer sliding barrier, can also be defined accordingly. In sharp contrast to the case of MoS2 homobilayer, here the energy band gap reduces with increasing twist angle. We find a remarkable interlayer charge transfer from MoTe2 to MoS2 which enlarges the band gap, but this charge transfer weakens with greater twisting and interlayer overlapping degree. Our discovery provides a solid basis in twistronics and practical instruction in band structure engineering of van der Waals heterostructures.