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 B2P6 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 B2P6 in various stacking configurations. The results show that B2P6/B2P6 stacking with type-II band alignment is the most stable configuration among the four bilayer B2P6 modes. Importantly, the band gap of bilayer B2P6 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 B2P6/B2P6 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 B2P6 exhibits triple enhancement compared to the monolayer, reaching 15442.45 cm2 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 B2P6 exhibits significant potential for next-generation electronic devices.