Band engineering and precipitation enhance thermoelectric performance of SnTe with Zn-doping

Abstract

We have systematically studied the thermoelectric properties in Zn-doped SnTe. Strikingly, band convergence and embedded precipitates arising from Zn doping, can trigger a prominent improvement of thermoelectric performance. In particular, the value of dimensionless figure of merit zT has increased by 100% and up to ∼ 0.5 at 775 K for the optimal sample with 2% Zn content. Present findings demonstrate that carrier concentration and effective mass play crucial roles on the Seebeck coefficient and power factor. The obvious deviation from the Pisarenko line (Seebeck coefficient versus carrier concentration) due to Zn-doping reveals the convergence of valence bands. When the doping concentration exceeds the solubility, precipitates occur and lead to a reduction of lattice thermal conductivity. In addition, bipolar conduction is suppressed, indicating an enlargement of band gap. The Zn-doped SnTe is shown to be a promising candidate for thermoelectric applications.

Investigation of vacuum evaporated SnTe thin films for their structural, electrical and thermoelectric properties

“…Therefore, the TE involvement due to the voltage drop is proportional to TS 2 /. The recently developed concepts such as band energy alteration and defect engineering [30][31][32][33][34][35][36][37] have been utilized to expand the thermoelectric efficiency (ZT) from 0.4 to 1.6. The value of ZT for pristine SnTe was found to be 0.4, but synergetic dominance of band energy modification and defect engineering effectively controlled 38 ZT up to 1.6.…”

“…Typically, SnTe is Sn-deficit; therefore, it acts as a p-type material. Bulk SnTe comprises a NaCl type cubic crystalline structure (space group (O ) 3 5 m Fm h  similar to PbTe and still played the role of promising TE material because its bulk electronic band configuration smartly resembles that of PbTe [30][31][32][33][34][35] . Due to the existence of two valence bands phenomenon, the hole density of states played a crucial role in different applications.…”

“…Due to the existence of two valence bands phenomenon, the hole density of states played a crucial role in different applications. The electronic band structure of SnTe usually resembles PbTe and PbSe band structure; therefore, it is clear that SnTe has a proper perspective and is used as excellent TE material [35][36][37][38][39][40] . SnTe thin films belong to topological crystalline insulators (TCI) studied for the nascence of line defects responsible for breaking crystalline isomorphism by the tenseness of film.…”

“…Figure 2 revealed the dependence of crystallite size on the thickness of the thin film and the effect of critical thickness relation. Earlier researchers 32,35,42 have also reported that for a vital thickness of thin film due to substrate, and other deposition parameters, the consequence of strain may be efficacious, but beyond that thickness, the deposited material acts like typical polycrystalline material. These features were considered due to the reduction of the intrinsic micro-strain property in the films and also due to an increase in the crystallite size 24 .…”

Electron delocalization enhances the thermoelectric performance of misfit layer compound (Sn1−x Bi x S)1.2(TiS2)2

“…Over 60% fossil fuels input for power generation is being rejected as low-grade heat annually. [1] Thermoelectric materials are able to directly convert such a huge amount of heat into utilizable electricity [2] without releasing any chemical residuals, showing great potential to contribute to solving the energy problem at present. [3,4] The efficiency of a thermoelectric device primary depends on the figure of merit, namely, ZT , of the thermoelectric materials used, which is defined as ZT = S 2 σ T /κ tot , [4] where S represents Seebeck coefficient, σ denotes electrical conductivity, their product S 2 σ is called power factor, T is the absolute temperature, and κ tot is the total thermal conductivity with contribution from both charge carriers (κ ele ) and phonons (κ lat ).…”