Predicting Two-Dimensional C 3 B/C 3 N van der Waals p-n Heterojunction with Strong Interlayer Electron Coupling and Enhanced Photocurrent.

The interlayer coupling in 2D van der Waals (vdW) heterostructures (HTS) plays the main role in generating new physics. However, the interlayer coupling is often weak, and little information on the strength of interlayer interaction in HTS is available. On the basis of density functional theory, we demonstrate that an effective electron coupling can be created in 2D C3 B/C3 N vdW HTS. The experimentally synthesized monolayers C3 B and C3 N are p- and n-type doped large gap semiconductors, respectively. However, the formed vdW HTS exhibits novel Dirac fermion. The strong interlayer electron coupling results in a large interlayer built-in electric field and improved optical properties of the 2D C3 B/C3 N vdW HTS. Moreover, a simple tight-binding model of C3 B/C3 N HTS with the nonzero interlayer hopping parameters captures the physical picture of interlayer coupling. Our results demonstrate the importance of interlayer electron coupling in the modulation of materials properties of 2D vdW HTS.