A Strategic Comparison Between Monolayers of WX₂N₄(X≐Si, Ge) Toward Thermoelectric Performance and Optoelectronic Properties.

Abstract

New 2D layered materials WX₂N₄(X≐Si, Ge)¹ are suitable for thermoelectric applications for a pretty good value of the figure of merit (ZT). Here, the thermoelectric properties of the 2D monolayer of WX₂N₄(X≐Si, Ge) using Density Functional Theory (DFT) is investigated combined with Boltzmann Transport Equation (BTE) along with spin‐orbit coupling (SOC). An excellent thermoelectric of 0.91 (0.92 with SOC) is obtained at 900 K for p‐type WGe₂N_4, and a of 0.81 (0.86 with SOC) is observed for n‐type at the same temperature. Furthermore, the WGe₂N₄ showed a of more than 0.7 (0.79 with SOC) at room temperature for p‐type. On the other hand, the WSi₂N₄ showed a comparatively lower at room temperature. However, the value increases significantly at higher temperatures, reaching 0.72 (0.79 with SOC) and 0.71 (0.62 with SOC) for p and n‐type at 900 K, respectively. The electronic band structure is examined and discovered that WSi₂N₄ and WGe₂N₄ possess indirect bandgaps (BG) of 2.68 eV (2.57 eV with SOC) and 1.53 eV (1.46 eV with SOC), respectively, according to Heyd‐Scuseria‐Ernzerhof (HSE) approximation. These materials may also be useful in UV and visible range optoelectronic devices because of their strong absorption in the respective regions.