Novel 2D Boron Nitride with Optimal Direct Band Gap: A Theoretical Prediction

A novel structurally stable 2D-boron nitride material, namely di-BN, is predicted by means of the first-principles simulations. This monolayer BN system is composed of the azo (NN) and diboron (BB) groups. Its in-plane stiffness is close to the monolayer h-BN. Usually, the boron nitride materials are semiconductors with large band gaps. However, the monolayer di-BN possesses a moderate direct band gap of 1.622 eV obtained from our HSE06 calculation. Although the GW correction enlarges the band gap to 2.446 eV, this value is still in the range of the visible light. The detailed investigation of its band arrangement reveals that this material is able to product hydrogen molecules in a photocatalytic water splitting reaction. Furthermore, its charge carrier mobilities are significantly higher than the other popular 2D semiconductors, e.g., MoS2 and phosphorene. Therefore, this 2D-BN material could have huge application potentials in the electronics and solar energy conversion fields.