Enhanced thermoelectric performance of β-Zn4Sb3 based nanocomposites through combined effects of density of states resonance and carrier energy filtering

Abstract

It is a major challenge to elevate the thermoelectric figure of merit ZT of materials through enhancing their power factor (PF) and reducing the thermal conductivity at the same time. Experience has shown that engineering of the electronic density of states (eDOS) and the energy filtering mechanism (EFM) are two different effective approaches to improve the PF. However, the successful combination of these two methods is elusive. Here we show that the PF of β-Zn4Sb3 can greatly benefit from both effects. Simultaneous resonant distortion in eDOS via Pb-doping and energy filtering via introduction of interface potentials result in a ~40% increase of PF and an approximately twofold reduction of the lattice thermal conductivity due to interface scattering. Accordingly, the ZT of β-Pb0.02Zn3.98Sb3 with 3 vol.% of Cu3SbSe4 nanoinclusions reaches a value of 1.4 at 648 K. The combination of eDOS engineering and EFM would potentially facilitate the development of high-performance thermoelectric materials.

In Operando Study of High‐Performance Thermoelectric Materials for Power Generation: A Case Study of β‐Zn4sb3

“…Previous studies identified these "nanoparticles" as nanoinclusions [17,26,33] , and further analysis shown later in this work also identify such nanoinclusions as a nanoprecipitated phase on the matrix of primary structure. Indexing the ring pattern [34] in Fig.…”

In Situ TEM Studies of Nanostructured Thermoelectric Materials: An Application to Mg‐Doped Zn4Sb3 Alloy

“…Creating nanostructures in TE materials is ap romising approach to obtain high zT by: [1] i) enhancing the density of state near Fermi level via quantum confinement that increases the thermopower to decouple thermopower and electrical conductivity;i i) reducing the thermal conductivity by introducing more phonon scattering on the nanostructures while preserving carrierm obility and electronic conduction.I nm ost nanostructured TE materials,u nderstanding the interplay between nanostructures and TE properties under dynamic conditions is important for developing high-performance and stable TE materials andd evices. [1] Nanocomposites with enhanced zT have been found in the various TE material families, including Bi 2 Te 3 -based nanocomposites, [5][6][7][8] PbTe-based nanostructured materials, [9][10][11] SiGe-based nanocomposites, [12][13][14][15] and ZnSb alloys, [16][17][18][19][20] etc. [4] Amongt heses trategies, nanocomposite TE materials, whichare designed to introduce nanometer-sized polycrystallinesa nd interfaces into bulk materials, can be considered as an effective approacht op roduce highperformance TE materials with low cost and large volume.…”

Thermoelectric power factor of nanocomposite materials from two-dimensional quantum transport simulations

“…While the impact of nanoinclusions on the thermal conductivity is well documented [18,45], previous works are not as clear on their impact on the power factor, with results varying significantly, from only small influence [30,31,34,46], to large potential improvements [25,36,42,47]. Thus, it is imperative that a high level of understanding on the influence of nanoinclusions on the power factor, both qualitative and quantitative, is also established, if ZT is to be maximized.…”

“…This is because in common thermoelectric materials, such as PbTe, a large * s.foster@warwick.ac.uk portion of the phonons have mean-free paths for scattering on the order of nanometers [29]. This technique is therefore widely used to enhance thermoelectric performance in a broad range of materials, including BiTe [30,31], PbTe [23,32,33], SiGe [16,34,35], ZnSb [25,36], FeSi [37], MnSi [38], SnTe [39], PbS [40], CuSe [41], YbCoSb [42], and ZrNiSn [43]. Indeed, by embedding nanoinclusions within PbTe in a hierarchical manner, record high ZT = 2.2 values were achieved due to drastic reductions in κ, but also due to retaining high power factors [23].…”

“…These include superlattices [15], alloying [16], heavy doping [17], nanoporous materials [18][19][20], and nanograining [21,22]. One of the most widespread methods for the reduction of the thermal conductivity has been the use of nanoinclusions [23][24][25][26][27][28]. These cause scattering of short-wavelength phonons and can produce significant reductions in κ.…”