Intrinsic direct bandgap semiconductor with high stability, strong anisotropy and controllable edge position in BrHfN monolayer

Based on first-principles calculations, the BrHfN monolayer has a direct band gap of 3.19 eV, and the edge position can be adjusted by applying pressure. The BrHfN monolayer meets the energy band structure requirements of photocatalytic water splitting. In addition, the calculation of cohesive energy shows the feasibility of the experiment. Ab initio molecular dynamics simulations at room temperature and phonon dispersion curves show the stability of the structure. Young's modulus can be as high as 158 N m(-1), and Poisson's ratio shows high anisotropy. High absorption coefficients, appropriate band edge positions and strong ability for carrier separation and transfer make it a promising candidate for photocatalytic water splitting. Additionally, the band structure and optical absorption of monolayer BrHfN can be effectively tuned by strain effect. Our research provides valuable insight for finding more potential functional two-dimensional semiconductors applied in optoelectronics, solar energy conversion, and photocatalytic water splitting.