Two-Dimensional Tellurene as Excellent Thermoelectric Material

ACS Appl. Energy Mater. 1, 5, 1950–1954 (2018)

We study the thermoelectric properties of two-dimensional tellurene by first-principles calculations and semiclassical Boltzmann transport theory. The HSE06 hybrid functional results in a moderate direct band gap of 1.48 eV at the Γ point. A high room temperature Seebeck coefficient (S_xx = 0.38 mV/K, S_yy = 0.36 mV/K) is combined with anisotropic lattice thermal conductivity (κ^l_xx = 0.43 W/m K, κ^l_yy = 1.29 W/m K). Phonon band structures demonstrate a key role of optical phonons in the record low thermal conductivity that leads to excellent thermoelectric performance of tellurene.  At room temperature and moderate hole doping of 1.2 × 10^-11 cm^–2, for example, a figure of merit of ZT_xx = 0.8 is achieved.