High Thermoelectric Performance SnTe–In₂Te₃ Solid Solutions Enabled by Resonant Levels and Strong Vacancy Phonon Scattering

Abstract

Herein, we report a significantly improved thermoelectric figure of merit ZT of ∼1.1 at ∼923 K in p-type SnTe through In 2 Te 3 alloying and iodine doping. We propose that the introduction of indium at Sn sites in SnTe creates resonant levels inside the valence bands, thereby considerably increasing the Seebeck coefficients and power factors in the low-to-middle temperature range. Unlike SnTe−InTe, the SnTe−In 2 Te 3 system displays much lower lattice thermal conductivity. Utilizing a model for point defect scattering, we analyze the origin of the low thermal conductivity in SnTe−In 2 Te 3 and attribute it mainly to the strong vacancy originated phonon scattering between Sn atoms and the vacancies introduced by In 2 Te 3 alloying and partly to the interfacial scattering by In-rich nanoprecipitates present in SnTe matrix. By alloying only In 2 Te 3 with SnTe, a ZT value of ∼0.9 at 923 K was achieved. ZT can be further increased to ∼1.1 at 923 K through adjusting the charge carriers by iodine doping at Te sites.

High anisotropic thermoelectric effect in palladium phosphide sulphide

“…This anisotropy in the thermopower values in the two different crystallographic directions might enable to design transverse thermoelectric device . Seebeck coefficient values of PdPS in both the p‐type and n‐type are quite high compared to thermoelectric materials reported for the temperature range 300–800 K. These values are more than three times higher of the reported binary chalcogenides and two times greater than CoSbS . Calculated n‐type thermopower of PdPS in z direction is similar as FeSbS, thermopower (μ along x direction) , however, for p‐type PdPS, we obtain much higher thermopower compared to FeSbS.…”

“…There has been a strong recent interest in novel high ZT materials . These new discoveries have expedited the search for an improved thermoelectric device via either improving power factor, P or reducing .…”

“…Recently transition metal compounds have been reported to have good power factor in the temperature range of 300–1000 K. has shown power factor ranging from 6–12 in the temperature range of 300–1000 K leading to high ZT value of 1.4 , and and based nanostructured compounds have also shown high values of power factor at room temperature . High power factor values around 23 have been obtained for SnTe and compound . Thermoelectric power generators based on cubic PbTe either n‐type or p‐type have , and Pb–Ag–Sb–Te alloys have in the temperature range 300–700 K. For commercial applications, Pb, and Te based compounds are being mainly used for waste heat recovery in 300–800 K, however, due to the toxicity of Pb, the use of the thermoelectric devices based on Pb alloy is restricted.…”

Analytical Models of Phonon–Point-Defect Scattering

“…In some of these studies, however, the primitive unit cell volume, instead of the volume per atom, is still used to calculate the disorder parameter u in Equation 1, which leads to an over-prediction of the lattice thermal conductivity reduction (see Supplementary Section 7.5) proportional to the number of atoms in the unit cell 6,[40][41][42] . Typically, however, a cancellation of errors prevents the general conclusions of these papers about the importance of point defect scattering from being incorrect 6,[40][41][42][43] . This effect is discussed in greater detail in Section 5 on the large scattering strength of vacancies and interstitial defects.…”

Solubility limits in quaternary SnTe-based alloys

“…[10][11][12][13] Promising results have been reported regarding the isoelectronic alloying of SnTe, specically for (Sn,Mn)Te and Sn(Te,Se). High solubility limits have been observed in previous studies of these systems (MnTe in SnTe < 13%, 14,15 SnSe in SnTe < 15% (ref.…”