Enhancing thermoelectric performance of Sn1-Sb2/3Te via synergistic charge balanced compensation doping

Enhanced Thermoelectric Performance of SnTe-Based Materials via Interface Engineering

“…It is worth noting that for some heavily doped SnTe-based systems (e.g., over 15% Mn-doped SnTe system 32 ), the SPB model might not be applicable and can yield unphysical lattice thermal conductivity values; however, the doping Sb level in our work is relatively low, so this equation is still applicable. 42,45,53 As can be seen, the κ e values of all SnTe− Sb x (x > 0) are significantly reduced due to the decrease in σ caused by Sb doping, while the κ l values of all the SnTe−Sb x (x > 0) are reduced, especially in SnTe−Sb 0.06 and SnTe−Sb 0.09 . Finally, a very low κ l of ∼0.64 W•m −1 K −1 at 873 K is achieved in SnTe−Sb 0.06 , which is ∼52% lower than that of the pristine SnTe pellet.…”

“…The detailed microstructure and nanostructure analyses clarify the existence of multi-scale crystal imperfections, mainly including a high density of 54 and ΔE v = 0.28 eV (green line) 43 and in comparison with reported data on undoped SnTe, 56 Sn 1−x Sb x Te, 50 and Sn 1−x Sb 2x/3 Te. 42 nanoprecipitates at the grain boundary, porous structures, dense grain boundaries, and stacking faults in the grains, which is expected to impact the phonon transmission of the material, 11,12 which will be discussed later. Figure 4a plots the temperature-dependent σ of all assintered pellets.…”

“…However, the SnTe−Sb 0.09 sample shows slightly lower S over 823 K compared with SnTe−Sb 0.06 , which may result from the bipolar effect in SnSb 0.09 Te that occurs at high temperature. 42,50 To understand the increased S in SnTe−Sb x (x > 0), we compared the n H -dependent S with the Pisarenko plot calculated by using a two-band model (Figure 4e). 42,50−54 As witnessed, all the S-n H data points of the SnTe−Sb x (x > 0) samples in this work are higher than the plotted Pisarenko line, which suggests the increased effective mass m* and indicates the valence band convergence effect in SnTe−Sb x (x > 0) (Figure 4f), 42,50,53,55 and we achieved a more optimized carrier concentration due to the extra Sn self-doping effect (compared with other Sn 1−x Sb x Te systems).…”

“…42,50 To understand the increased S in SnTe−Sb x (x > 0), we compared the n H -dependent S with the Pisarenko plot calculated by using a two-band model (Figure 4e). 42,50−54 As witnessed, all the S-n H data points of the SnTe−Sb x (x > 0) samples in this work are higher than the plotted Pisarenko line, which suggests the increased effective mass m* and indicates the valence band convergence effect in SnTe−Sb x (x > 0) (Figure 4f), 42,50,53,55 and we achieved a more optimized carrier concentration due to the extra Sn self-doping effect (compared with other Sn 1−x Sb x Te systems). Consequently, a maximum S of ∼170 μV•K −1 and an enhanced PF of ∼2320 μW•cm −1 •K −2 are obtained (Figure S3a) in the SnTe−Sb 0.06 sample, which is enhanced by ∼34% compared with that of pristine SnTe.…”

Enhanced Thermoelectric Performance Achieved in SnTe via the Synergy of Valence Band Regulation and Fermi Level Modulation

“…In order to tune the thermal and electrical transport properties in the SnTe system, a lot of effective strategies have been investigated in previous works. In order to reduce the lattice thermal conductivity ( κ lat ), nanoprecipitates, such as Cu 2 Te and CdTe, and interstitial point defects, reported by Pei et al, were introduced as the strong scattering centers to impede phonon propagation; additionally, introducing short-range van der Waals gaps was recently revealed to be another effective way to strengthen phonon scattering by Xu et al, Liu et al, and Lyu et al In order to achieve improved electrical performance, introducing a resonant state via In doping was reported to achieve an enhanced power factor ( PF ) by Zhang et al; moreover, creating band convergence by Mg/Mn/Cd/Hg doping in SnTe significantly increased the density of states (DOS) effective mass ( m d * ), resulting in a high electrical property. Despite the fact that the aforementioned doping/alloying on Sn sites can modify the band structure and/or decrease the κ lat value, this kind of strategy alone always results in a side effect that the charge carrier concentration was usually moved out of its optimal area.…”