Electrical and thermal transport properties of Pb_1−xSn_xSe solid solution thermoelectric materials

Abstract

Both lead selenide (PbSe) and tin selenide (SnSe) are promising thermoelectric compounds consisting of earth-abundant elements, between which solid solutions can be formed over a wide composition range. This study investigated the electrical and thermal transport properties of n-type Pb1-xSnxSe (x = 0, 0.01, 0.05, 0.1 and 0.15) solid solutions with emphasis on the effect of Sn substitution. Small amounts of Sn substitution (x ≤ 0.1) increased electrical conductivity but showed less influence on the Seebeck coefficient, leading to improved power factors, which were revealed to be associated with the generation of native Se vacancies. The electrical conductivity tended to decrease when x > 0.1 due to the alloying effect, consequently the thermoelectric figure of merit was not further increased, even though the thermal conductivity can be reduced by increasing Sn content. A maximum dimensionless figure of merit ZT of up to 1.0 was obtained at moderate temperature (773 K) for the composition of Pb0.9Sn0.1Se.

High-performance SnSe thermoelectric materials: Progress and future challenge

“…The introduction of appropriate inclusions in polycrystalline SnSe can achieve a high peak ZT in SnSe system [84,276]. Many different types of inclusion, such as second phase (SnSe 2 [84] and Se nanowires [297]), nanoprecipitates (rock-salt-type SnSe [141] and Sn oxides [67]), simple substance (carbon black nanoinclusions [298]), compounds (SnS [129,299], 2D-MoSe 2 [300]) and compounds (SiC [259] and PbTe [301] SnS [257]. SnSe can also be treated as inclusion in other thermoelectric materials systems, such as (Cu 2 Se) 0.97 (SnSe) 0.03 [303], and (PbSe) 0.9 (SnSe) 0.1 [257].…”

“…Apart from XRD, XPS can also be used to analyze the phase of SnSe[81,[264][265][266].Figure 25(b)shows a partial high resolution XPS spectrum of SnSe synthesized via solvothermal route[81], indicating the existence of one valence state for Sn and Se. The peaks of Sn 3d 3/2 and Sn 3d 5/2 were singlet and no accessorial binding energy peaks can be found, indicating the divalent characteristic of Sn ions, and a binding energy peak of Se 3d was also observed at 53.7 eV, suggesting Se 2+[81].To determine the compositional ratio of Sn and Se in the materials, EDS[267][268][269] and high-resolution electron probe micro-analysis (EPMA)[81,91,128,257] are commonly used.Figure 25(c)shows a typical EDS spot analysis of SnSe synthesized by microwave-assisted solvothermal route, the atomic ratio of Sn and Se was roughly 1:1.…”

Thermoelectric SnS and SnS-SnSe solid solutions prepared by mechanical alloying and spark plasma sintering: Anisotropic thermoelectric properties

“…These materials in their pristine form possess high Seebeck coefficient and low thermal conductivity but low electrical conductivity due to the low carrier concentration which results in low ZT values. Electrical conductivity can be enhanced by optimizing carrier concentration through elemental doping and band convergence 5 6 7 8 9 10 , while thermal conductivity can be suppressed via forming solid solutions (alloying) 11 12 , nanostructure architecture and microstructure modulation 13 14 15 16 17 18 19 by virtue of intensifying phonon scattering at atomic, nano and micro scales, respectively. Among these strategies, forming solid solutions 20 21 22 23 has also been revealed as an effective way to modify the band structures: it can alter the band shape 24 (effective mass), change the band gap 25 (related to bipolar effect), and also affect the relative position of different bands 10 26 (band alignment and convergence), thus directly determining charge transport and thermoelectric performance.…”

Copper Sulfides: Earth‐Abundant and Low‐Cost Thermoelectric Materials

“…So, by adjusting the chemical complexity, such as variation of fractions of the elements, one can systematically modify the thermal conductivity . Also, interesting properties are observed through manipulating the structures and electronic band structures in some of the solid alloy solution systems, such as PbTe‐PbSe, PbTe‐PbS, PbSe‐PbS, PbSe‐SnSe, PbTe‐PbSe‐PbS, SnSe‐SnS, and so on, which are considered as important materials for future applications.…”

“…Several approaches are introduced as modern concepts to improve the thermoelectric performance; these are design of alloys, fabrication of heavy element compound, complex crystal structuring, resonant level doping, and so on, aiming to create PGEC. Despite all these classical approaches, there is one more important strategy called nanostructurization, which is proven to be very promising .…”