Programme

O.1 -- Oral, NCTP-43

Date: Monday, 30 July 2018

Time: 10:30 - 10:50

Oxygen substituted bismuth telluride: a new promising thermoelectric material

Tran Van Quang

Department of Physics, University of Transport and Communications, Hanoi, Vietnam

We address an issue of the effect of oxygen substitution on the electronic structure and the thermoelectric property of bismuth telluride by employing first-principles calculation and the semi-classical Boltzmann transport theory. The newly formed compound, Bi2O2Te, is found to be a narrow band gap semiconductor with the band gap of Eg=0.13 eV. Significant enhancement of the Seebeck coefficient is found and originated from the presence of the flat band at the band edge which gives rise to the steep slope of density of states near Fermi energy. This is responsible for the enhancement of the power factor. Using the experiment-thermal conductivity of Bi2O2Te, we found that the figure of merit of ZT is about 0.06 at room temperature for n-type doping. Interestingly, it is significantly improved to be 0.33 with optimized carrier concentration. It is even more increased with the increase of temperature for both p and n type dopings. We suggest that Bi2O2Te is a promising thermoelectric materials with carrier concentration optimized for use in the moderate-temperature thermoelectric energy conversion.

Presenter: Tran Van Quang