Structural Preferences of Metal Chalcogenide based Nanothreads (MX; M=Au, Ag; X=S, Se): A Computational Study

Abstract

AbstractThis study investigates the structural stability and electronic properties of α‐MX nanothreads and β‐MX nanosheets (M=Au, Ag; X=S, Se) using density functional theory. Our findings confirm the thermal and dynamic stability of all nanostructures, with β‐MX phases being more stable than α‐MX, albeit with minimal energy differences between the two phases. Electron localization analysis reveals predominantly ionic bonding character between M (Ag and Au) and X (S and Se) atoms. All the phase exhibits metallophilic interactions (Argentophilic and Aurophilic), with α‐MX nanothreads demonstrating a higher level of interaction compared to β‐MX nanosheets, attributed to the curvature inherent in the nanothreads. Significantly, these interactions are effectively small and do not compromise the relative stability between the α‐MX and β‐MX phases. Additionally, both α‐MX and β‐MX structures exhibit characteristics of indirect bandgap semiconductor behaviour. The band gap values do not significantly differ between α‐MX and β‐MX phases. Fermi analysis reveals that α‐MX phases exhibit small effective electron masses and large hole mobility along the uniaxial direction. These findings suggest promising prospects for α‐MX nanothreads as 1D semiconductors in nano‐electronics and nano‐optoelectronics applications in the future.