Emerging quasi-one-dimensional material NbS₄ with high carrier mobility and good visible-light adsorption performance...

Due to their unique structure, abundant properties and potential applications, low-dimensional materials with covalently bonded building blocks through van der Waals (vdW) interactions have sparked widespread interest. Recently, the bulk phase NbS₄ consisting of one-dimensional (1D) chains has been synthesized successfully, adding a new member to the group V metallic polychalcogenide family. In the present study, based on density functional theory calculations, we obtained a better understanding of the stability, mechanical properties, electronic structures, transport properties and optical performances of the bulk phase NbS₄. Furthermore, the possibility of exfoliating 1D single-chain nanowires from the bulk phase was uncovered. Both bulk phase and 1D nanowires show dynamic, thermal, and mechanical stabilities. The bulk phase possesses an indirect band gap of 1.39 eV with high anisotropic carrier mobilities of 471.814 cm² s^-1 v^-1 for electrons (along the b axis direction) and 546.92 cm² s^-1 v^-1 for holes (along the a axis direction). The single-chain nanowire exhibits remarkable flexibility and can resist 24% tensile strain along the chain direction. The decreased dimension from the bulk phase to the individual 1D chain not only makes the band gap increase to 1.81 eV but also results in an indirect-to-direct band gap transition, indicating a strong quantum confinement effect. The 1D single-chain nanowire also shows high carrier mobilities of 111.91 cm² s^-1 v^-1 for electrons and 316.63 cm² s^-1 v^-1 for holes along the chain direction. In addition, both bulk phase and 1D nanowire display excellent visible light absorption performance along the chain direction and the absorption coefficients reach the order of 10⁶ and 10⁵ cm^-1. These promising properties render quasi 1D NbS₄ as candidate materials for nanoscale applications in high-performance optoelectronic and nanoelectronic devices. The predicted unconventional properties of NbS₄ not only provide a meaningful complement to the fascinating quasi 1D material family, but also will attract extensive interest from a wide audience to explore unanticipated properties and design new nanoscale devices based on NbS₄.