Assessment of electronic structure, optical properties, and performance of bismuth telluride (Bi2Te3) based thermoelectric generators

This article presents the electronic and optical properties, as well as the performance assessment, of a thermoelectric generator utilizing Bi2Te3 through simulation studies. The computational methods employed include density functional theory and molecular dynamics. Analysis of the electronic band structure confirms the presence of a direct bandgap, while the multiple local maxima identified in the density of states suggest that Bi2Te3 can sustain high charge carrier concentrations. The absorption spectrum indicates significant absorption across the visible to infrared spectrum, and the optical conductivity peak at 4.8 eV signifies a robust electronic response linked to interband transitions. It was found that the lattice thermal conductivity decreases with increasing temperature due to enhanced phonon scattering, whereas the electronic thermal conductivity rises with temperature as more charge carriers undergo thermal excitation. Conversely, electrical conductivity decreases, primarily due to the predominance of phonon scattering at elevated temperatures. The Seebeck coefficient increases with temperature, which is attributed to the broadening of the energy distribution of electrons, thereby enhancing charge carrier participation in the thermoelectric mechanism. By integrating these calculated thermoelectric properties, the dimensionless figure of merit (ZT) was derived, and the efficiency of the Bi2Te3-based thermoelectric generator was estimated to be ∼7.56% when the sink temperature is held constant at 300 K while varying the source temperature between 300 and 800 K.