Unrevealing the structure and properties of α-sheet-based bilayer borophenes

Abstract Recent experimental realizations of bilayer boron materials motivated us to study the structure and properties of α-sheet-based bilayer borophenes with interlayer covalent bonds. As shown here, at least three stacking variations are possible: AA, AB, and AB'. The on-top AA-stacking has been obtained experimentally. The AB-stacking is the most stable among neutral freestanding structures, whereas the AA and AB' stacking sequences are very close in energy, both for neutral and negatively charged cases. The studied bilayer borophenes exhibit extraordinarily high electric conductivity with values as high as ~107 S/m for the experimentally observed AA-stacking. The highly stable AB-stacking bilayer, reported here for the first time, exhibits an anisotropic conductivity with an average value of 6.0 x 106 S/m.