Bilayer Janus B ₂ P ₆ : Tunable Band Gap and Dipole Moment with High Carrier Mobility

For the advancement of next-generation nanoscale technologies, two-dimensional (2D) materials have generated significant interest. However, the low carrier mobility in nanoscale devices greatly hinders their development. Recently, the Janus 2D B 2 P 6 has been predicted, combining anisotropic electronic transport with high electron mobility. Here, first-principles computations are used to examine the structure, electrical properties, and carrier mobility of bilayer B 2 P 6 in various stacking configurations. The results show that B 2 P 6 /B 2 P 6 stacking with type-II band alignment is the most stable configuration among the four bilayer B 2 P 6 modes. Importantly, the band gap of bilayer B 2 P 6 can be regulated from 1.24 to 0.08 eV by changing the stacking modes and interlayer distance and applying biaxial strain. The dipole moment of bilayer B 2 P 6 /B 2 P 6 increases in the Z -direction, resulting in a high dipole moment of 0.353 e·Å, which is positively correlated with the increase in the electrostatic potential difference. Furthermore, the electron mobility in bilayer B 2 P 6 exhibits triple enhancement compared to the monolayer, reaching 15442.45 cm 2 V –1 s –1 in the x -direction. It is confirmed that the deformation potential and elastic moduli play major roles in determining the carrier mobility. Thus, the bilayer Janus B 2 P 6 exhibits significant potential for next-generation electronic devices.