RESUMO
From a device perspective, achieving great merits for both n- and p-type thermoelectric systems is particularly desirable. By first-principles calculations, electronic, phonon, and thermoelectric transport properties of 2D SiTe with three different structural phases are investigated, which are quadruple layer (QL), black-phosphorene-like (α-SiTe) and blue-phosphorene-like (ß-SiTe), respectively. Of these three structure phases, ß-SiTe possesses the best thermoelectric properties. This is because the DOS peak near the valence band results in a high Seebeck coefficient, further leading to a high power factor. We also demonstrate that strong phonon scattering heavily influences the lattice thermal conductivity K l of ß-SiTe. With the combination of high power factor and low K l, the ZT max value of ß-SiTe reaches 0.95 at T = 1300 K for both n- and p-type doped systems. Therefore, 2D ß-SiTe is a promising candidate for future high-temperature solid-state thermoelectric generators with a balanced performance of the n- and p-legs.
RESUMO
Structural and electronic properties of two-dimensional stanene and graphene heterostructure (Sn/G) are studied by using first-principles calculations. Various supercell models are constructed in order to reduce the strain induced by the lattice mismatch. The results show that stanene interacts overall weakly with graphene via van der Waals (vdW) interactions. Multiple phases of different crystalline orientation of stanene and graphene could coexist at room temperature. Moreover, interlayer interactions in stanene and graphene heterostructure can induce tunable band gaps at stanene's Dirac point, and weak p-type and n-type doping of stanene and graphene, respectively, generating a small amount of electron transfer from stanene to graphene. Interestingly, for model [Formula: see text] , there emerges a band gap about 34 meV overall the band structure, indicating it shows semiconductor feature.
