Low lattice thermal conductance of buckled GeTe/antimonene vdW interface device: A DFT + NEGF study

Abstract

Motivated by the exceptional thermoelectric performance of 2D buckled GeTe and Sb monolayers, thermoelectric transport characteristics of the stable GeTe/Antimonene (Sb) van der Waals heterostructure (vdWH) are examined by first-principles calculations supplemented by the non-equilibrium Green’s function approach (NEGF). The electronic aspects of these thermoelectric devices are assessed by reviewing the Seebeck coefficient (S) and electrical conductance (G_e) derived from transmission spectra. Simultaneously, the thermal conductance (κ_ph) of the system was computed by analysing the lattice/phonon transmission spectrum. The thermoelectric figure of merit (ZT) for the system is calculated by integrating the electron and phonon transmission spectra across various chemical potentials (μ) and temperatures (T). In this context, the heterostructure featuring a smaller interlayer vdw gap and reduced phonon thermal conductance ultimately exhibits superior thermoelectric performance. The effective phonon scattering at the interface establishes reduced phonon thermal conductance at the heterostructure. At 300 K, low phonon thermal conductance attains 43.23 pW/K and the highest ZT attains 6.97 for heterostructure. Our theoretical research provides an innovative technique and offers valuable theoretical insights into the thermoelectric transport properties of vdW heterostructures device.