First-principles investigations of structural, electronic and thermoelectric properties of β-Sb/Gel_2 van der Waals heterostructures

摘要

Two-dimensional materials offer the potential to attain nanoscale optoelectronic and thermoelectric devices. In this paper, the electronic structure and thermoelectric potential of beta-Sb/GeI2 van der Waals (vdW) heterostructures with two different stacking configurations (AA and BA) were investigated using first-principles calculations in the framework of density functional theory combined with the semi-classical Boltzmann theory. Band gaps of 1.25 and 2.18 were extracted from the band structures for the beta-Sb and GeI2 monolayers, respectively. For the AA and BA stacking of the beta-Sb/GeI2 heterostructure, band gaps of 0.86 and 0.75 eV were calculated, respectively. We also analyzed the effect of temperature and chemical potential on transport properties. Interestingly, high electronic figure of merit ZT(e) values of 6.61 (at 0.067 Ry) and 44.40 (at -0.037 Ry) were achieved for AA and BA stacking at room temperature, respectively. Moreover, the ZT(e) increased sharply, showing a giant value of 17.69 (at 380 K) for AA stacking. However, for BA stacking a decreased value of 26.67 (at 420 K) was achieved, which was attributed to the Seebeck coefficient value, indicating very good potential for beta-Sb/GeI2 heterostructures in energy harvesting and solid-state cooling applications.