Enhanced electronic and thermoelectric properties of Zr[formula omitted]CO[formula omitted]/GaS van der Waals heterostructure: A First-principles study

Abstract

Herein, we reported the electronic and thermoelectric properties of electron (n) and hole (p) doped Zr2CO2 monolayer, GaS monolayers, and Zr2CO2/GaS van der Waals heterostructures using density functional theory together with Boltzmann transport equations. Negative formation energies demonstrate the thermodynamic stability of isolated monolayers and Zr2CO2/GaS van der Waals heterostructures. We found that both Zr2CO2 and GaS monolayers are semiconductors with an indirect bandgap of 0.98 eV and 2.54 eV, respectively. Furthermore, stacking Zr2CO2 on the GaS monolayer results in an increased bandgap of 1.41 eV. The transport characteristics are computed as a function of temperature in the range 300 K–500 K and charge carrier concentrations in the range of 1.0×1018–1.0×1020 cm−3. At room temperature, the figure-of-merit ZT projected value for the n(p) doped Zr2CO2 monolayer is as high as 0.92 (0.84). In addition, we found increased (decreased) electronic conductivity (electronic thermal conductivity) for Zr2CO2/GaS van der Waals heterostructure. The ZT for the n(p) doped Zr2CO2/GaS van der Waals heterostructure increased significantly to 1.03 (0.88) at 500 K. Figure-of-merit ZT ≥1 indicates that Zr2CO2 based van der Waals heterostructure is an efficient material for thermoelectric devices application. Our results provide new guidance for designing new efficient thermoelectric materials with broad application in thermoelectric devices.