Unrevealing the structure and properties of {$\alpha$}-sheet-based bilayer borophenes

TL;DR

This study investigates the structure, stability, and electrical conductivity of various stacking configurations of $oldsymbol{ extalpha}$-sheet-based bilayer borophenes, revealing highly conductive properties and identifying the most stable stacking arrangements.

Contribution

It provides the first detailed analysis of the stability and electrical properties of different stacking variations in bilayer borophenes, including the newly identified stable AB-stacking.

Findings

AA-stacking is experimentally realized and highly conductive (~10^7 S/m).

AB-stacking is the most stable configuration among neutral bilayer borophenes.

AB-stacking exhibits anisotropic electrical conductivity (~6.0 x 10^6 S/m).

Abstract

Recent experimental realizations of bilayer boron materials motivated us to study the structure and properties of $\alpha$-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 ${\sim} 10^7\mathrm{~S}/\mathrm{m}$ 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 $6.0 \times 10^6~\mathrm{S/m}$.