A type-II blue phosphorus/MoSe2 van der Waals heterostructure: improved electronic and optical properties via vertical electric field

Building novel van der Waals (vdW) heterostructures is of great interest and is important to improve the performance of individual two-dimensional materials. Using first-principles calculations, we demonstrate that the constructed blue phosphorus/MoSe2 (P-2/MoSe2) vdW heterostructure has a unique type-II band alignment and a suitable bandgap (about 1.63 eV) for optoelectronic applications. Its electronic and optical properties depend strongly on the applied vertical electric field. The quasi-particle bandgap of the P-2/MoSe2 can be linearly modulated by about 1.11 eV under the applied electric field and the type-II band alignment persists in a broad range. Meanwhile, the negative electric field induces a significant red-shift of the optical absorption edge of P-2/MoSe2, greatly enhancing its absorption for the visible and near-infrared lights, which is desirable for optoelectronic applications. More importantly, the observed interlayer excitons with large binding energy (more than 600 meV) can be preserved under the applied electric field, being very much beneficial for the real separation of photoexcited carriers. These results indicate that the P-2/MoSe2 vdW heterostructure can become a good candidate for optoelectronic devices.