Unexpectedly high thermoelectric performance of anisotropic Zr2Cl4 monolayer

Abstract

Recently, the Hf2Cl4-type materials as functional materials have attracted broad interest because of their enormous potential in thermoelectric (TE) applications. However, relevant investigations are still scarce up to now. To explore the Hf2Cl4-type materials with excellent TE properties, we focus on the TE properties of Zr2Cl4 monolayer and calculate the TE parameters based on first-principles calculations and Boltzmann transport equation. Although, as compared to some typical TE materials, it exhibits better heat transport and thus higher lattice thermal conductivity, the figure of merits (ZT) of both p-type and n-type Zr2Cl4 reach an unexpectedly high value of 3.90 and 3.60, respectively, owing to the larger electrical conductivity and higher power factor. Additionally, owing to the prominent difference in electrical conductivity between the x- and y-direction, strong anisotropy in ZT values is observed. Our study reveals that both n-type and p-type Zr2Cl4 monolayers have the potential for future TE applications.