1D group V-VI-VII ternary nanowires: moderate band gaps, easy to exfoliate from bulk, and unexpected ferroelectricity

One-dimensional nanowires have emerged as compelling ideal materials due to their characteristic structure, properties, and applications in nanodevices. Herein, based on experimental vdW-chain bulk crystals, a series of one-dimensional (1D) X^VY^VIZ^VII (X = As, Sb, Bi; Y = S, Se, Te; Z = Cl, Br, I) ternary nanowires are theoretically investigated. Such exfoliated 1D nanowires possess excellent stability and moderate band gaps (1.76-3.16 eV). The calculated electron mobilities were found to reach a magnitude of 10² cm² V^-1 s^-1 and even up to 322.95 cm² V^-1 s^-1 for 1D BiSeI nanowires, which are much larger than those of the previously reported 1D materials. Furthermore, the appropriate band edge alignments and considerable optical absorption endow 1D X^VY^VIZ^VII nanowires with prospective photocatalytic properties for water splitting. Notably, AsSI and AsSeI nanowires possess a unique non-centrosymmetric structure and exhibit promising 1D ferroelectricity. Large spontaneous polarization values, P_s, of 11.31 × 10^-10 and 6.92 × 10^-10 C m^-1 are obtained for 1D AsSI and AsSeI nanowires, respectively, and such 1D ferroelectricity can be regulated by intra-chain strains. Our calculations not only broaden the family of 1D materials but also reveal their great potential applications in electronic, optoelectronic, and ferroelectric devices.