Quasiparticle Effects and Strong Excitonic Features in Exfoliable 1D Semiconducting Materials.

Abstract

We report a first-principles study of the electronic and optical properties of recently identified one-dimensional semiconducting materials exfoliable from van der Waals-bonded bulk crystals. Specifically, we investigate four chalcogenide-based atomic chains, the covalently bonded S₃ and Te₃ chains, and polar-bonded As₂S₃ and Bi₂Te₃ chains, using a fully first-principles approach that combines density functional theory (DFT), density functional perturbation theory (DFPT), and many-body perturbation theory within the <i>GW</i> approximation and Bethe-Salpeter equation (BSE). Our vibrational analysis shows that the isolated, freestanding wires remain dynamically stable, with the zone-center optical phonon modes leading to infrared activity. The main finding of this study is the presence of very strong exciton binding energies (1-3 eV), which make these exfoliable 1D materials suitable platforms for room-temperature excitonic applications. Interestingly, the exciton character remains Wannier-Mott-like, as indicated by average electron-hole separations greater than the lattice constant. Notably, the optical gaps of these materials span a wide range ─ from infrared (0.8 eV, Bi₂Te₃), through the visible spectrum (yellow: 2.17 eV, Te₃; blue: 2.71 eV, As₂S₃), up to ultraviolet (4.07 eV, S₃) ─ highlighting their versatility for broadband optoelectronic applications. Our results offer a detailed, many-body perspective on the optoelectronic behavior of these low-dimensional materials and underscore their potential for applications in nanoscale optoelectronic devices.