A family of Li_xB_y monolayers with a wide spectrum of potential applications

Using first-principles calculations and evolutionary structure search, we predict a series of kinetically and thermodynamically stable Li_xB_y monolayers. While the Li₂B₂ monolayer (metallic) is found to be isotropic, the Li₄B₈ (metallic), Li₂B₆ (indirect bandgap semiconductor with a gap size similar to that of bulk Si), and Li₂B₁₂ (metallic) monolayers are anisotropic. Notably, the Li₂B₂ monolayer has a small Poisson's ratio, the Li₂B₆ monolayer achieves a high hole mobility of 6.8 × 10³ cm²·V⁻¹·s⁻¹ (as required for high-speed electronic devices), and the Li₂B₁₂ monolayer is auxetic.