Department of Applied Physics, School of Engineering, The University of Tokyo, Tokyo 113-8656
The electronic structures and thermoelectric properties of 12 parent compounds for thermoelectric materials were compared, from first-principles calculations and numerical solutions of Boltzmann transport equations. Carrier doping level dependences of the maximum possible thermoelectric figures of merit ZeT were calculated, in the limit of zero phonon thermal conductivity and infinite electron relaxation time. High enough ZeT was only observed in semiconductors with finite bandgaps. Higher ZeT was expected in compounds with steep density of states at the band edge. Such electronic structures were found in transition metal compounds, especially in transition metal oxides. We evaluated the temperature dependence of electron relaxation time, by combining calculation results with experimental transport properties. These analyses reduce the number of experiments to search for new thermoelectric materials, and will reveal the nature of various electron scattering centers within the thermoelectric materials.
thermoelectric materials, first-principles calculations, Boltzmann transport theory
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