We investigate the electronic properties of bilayer MoS2 exposed to an external electric field by using first-principles calculations. It is found that a larger interlayer distance, referring to that by standard density functional theory (DFT) with respect to that by DFT with empirical dispersion corrections, makes indirect-direct band gap transition possible by electric control. We show that external electric field effectively manipulates the valence band contrast between the K- and Γ-valleys by forming built-in electric dipole fields, which realizes an indirect-direct transition before a semiconductor-metal transition happens. Our results provide a novel efficient access to tune the electronic properties of two-dimensional layered materials.

Dynamic quantum-confined stark effect in self-assembled InAs quantum dots Appl. Phys. Lett. 78, 931 (2001); 10.1063/1.1348305Quantum-confined Stark effects of InAs/GaAs self-assembled quantum dot