Data-driven analysis of electron relaxation times in PbTe-type thermoelectric materials

Abstract

Data mining from published papers can generate large experimental datasets that have been overlooked in computational materials informatics. We developed an open web system Starrydata2 to accelerate a comprehensive digitization of data of materials from as-reported plot images in published papers, without sample selection based on performance. By plotting results obtained from our dataset on experimental thermoelectric properties of 434 samples of rock-salt-type (PbTe-type) thermoelectric materials, we revealed differences in electronic structure of parent compounds PbTe, PbSe, PbS, and SnTe from just experimental data. We observed that the calculated Seebeck coefficients were fairly consistent with experimental data for n-type PbTe but not for p-type PbTe, indicating possible modifications in its valenceband electronic structure. We evaluated the electron relaxation time τ el from 207 reported samples of n-type PbTe by combining calculations and experimental data. We found that τ el is not a constant but varies by at least two orders of magnitude. Achieving long τ el was suggested to be critical in increasing the thermoelectric figure of merit ZT.

Monolayer Ag2S: Ultralow Lattice Thermal Conductivity and Excellent Thermoelectric Performance

“…This range is typical of thermoelectric materials according to fitting results of theoretical data to experimental Seebeck coefficients and electrical conductivities. 39 For electron doping we find that τ is larger in the y-than the x-direction (Table 1) and, at the same time, that ZT is higher at identical τ (Figure 6), implying that the thermoelectric performance is superior in the y-direction as compared to the x-direction. This superiority is definitely because of the electron transport coefficients, as κ l is larger in the y-than the x-direction (Figure 4b).…”

Physical Insights on the Lattice Softening Driven Mid‐Temperature Range Thermoelectrics of Ti/Zr‐Inserted SnTe—An Outlook Beyond the Horizons of Conventional Phonon Scattering and Excavation of Heikes’ Equation for Estimating Carrier Properties

“…Typically, a TE material's carrier concentration and mobility are measured using the Hall effect (in a magnetic field) and electrical resistivity. When one looks at the Starry‐Data2, an extensive database developed by Y. Katsura et al., [ 72 ] abundant information is available on the transport properties of TE materials, but only a few of them have reported the Hall effect data. Moving forward, considering the limitations with Hall measurements (access to facilities, contact issues with the van der Pauw method, sample geometry constraints, etc.…”

Effective Mass from Seebeck Coefficient

“…Some 6000 papers with Seebeck coefficient data (from over 35 000 samples) are readily available on StarryData2 [ 50 ] as of 2021, whereas only 54 of those papers report Hall measurements. In many cases only the room temperature Hall effect is reported.…”