講演情報
[10p-N201-7]Effective Mass Model for Thermopower and Power Factor Analysis in Thermoelectric Materials
〇(PC)Andrei Novitskii1, Takao Mori1,2 (1.NIMS, 2.Tsukuba Univ.)
キーワード：
semiconductor、thermopower、thermoelectric materials
Despite its simplicity and several idealized assumptions (simple power-law energy-dependent scattering, single-band transport, etc.), the effective mass model remains a widely used and practical tool for first-order description of a thermoelectric material's electronic structure. Often, this is a reasonable approximation in regard to charge transport properties. In this study, we critically revisit the analytical expressions for the thermopower and reexamine the boundaries of their applicability, particularly in the partially degenerate region.
We demonstrated that regardless of the dominating scattering mechanism, the Pisarenko’s formula exhibit reasonable agreement with the full numerical solution when the thermopower is above 145 µV/K. Moreover, this formula provides a simple thermopower-conductivity relation, alpha = k_B/e*(b-ln(sigma)), where b is a constant determined by the scattering mechanism and weighted mobility mu_w, and sigma is the electrical conductivity. This relation, in turn, is valid for materials with alpha > 90 µV/K when acoustic phonon scattering is predominant. Additionally, the Pisarenko’s formula can be used to estimate the maximum power factor of a thermoelectric material from the weighted mobility of a single, not necessarily optimized, sample at any given temperature.
This analysis offers a convenient and broadly applicable approach to analyze thermoelectric transport. Even in cases where experimental data deviate from analytical prediction, the trends can be used to identify anomalies in transport behavior or to guide further investigations.
This work was supported by JST Mirai JPMJMI19A1.
We demonstrated that regardless of the dominating scattering mechanism, the Pisarenko’s formula exhibit reasonable agreement with the full numerical solution when the thermopower is above 145 µV/K. Moreover, this formula provides a simple thermopower-conductivity relation, alpha = k_B/e*(b-ln(sigma)), where b is a constant determined by the scattering mechanism and weighted mobility mu_w, and sigma is the electrical conductivity. This relation, in turn, is valid for materials with alpha > 90 µV/K when acoustic phonon scattering is predominant. Additionally, the Pisarenko’s formula can be used to estimate the maximum power factor of a thermoelectric material from the weighted mobility of a single, not necessarily optimized, sample at any given temperature.
This analysis offers a convenient and broadly applicable approach to analyze thermoelectric transport. Even in cases where experimental data deviate from analytical prediction, the trends can be used to identify anomalies in transport behavior or to guide further investigations.
This work was supported by JST Mirai JPMJMI19A1.