Design of 2D V₆S_nSe_6-nCl₆ (n=0, 2, 3, 5) with multilayer kagome lattice and ultrahigh electron mobility

Abstract

Two-dimensional (2D) kagome materials have attracted considerable attention due to their unique electronic properties. Based on first-principles calculations and employing the "1+3" design strategy, we designed a class of composition-tunable 2D multilayer kagome materials, V₆S_nSe_6-nCl₆, and identified four stable structures: V₆Se₆Cl₆, V₆S₂Se₄Cl₆, V₆S₃Se₃Cl₆, and V₆S₅Se₁Cl₆. 2D V₆S_nSe_6-nCl₆ possesses three kagome layers, two of which are vanadium-based kagome layers, and the other is a sulfur or selenium atomic layer. Electronic structure analysis reveals that 2D V₆S_nSe_6-nCl₆ is a narrow direct-bandgap semiconductor with a bandgap ranging from 0.568 to 0.742 eV, and exhibits ultrahigh electron mobility up to 4*10⁴ cm²V^-1s^-1 . Orbital analysis further demonstrates that the bands contributed by the V-based kagome layers form flat bands and Dirac cones below the Fermi level, and show a relatively high Fermi velocity. In summary, 2D V₆S_nSe_6-nCl₆ provides an excellent platform for kagome physics research and the fabrication of nanoelectronic devices, adaptable to various device scenarios.