Enhancement of thermoelectric performance via weak disordering of topological crystalline insulators and band convergence by Se alloying in Pb0.5Sn0.5Te1 − xSex

Ginting, Dianta; Lin, Chan Chieh; Kim, Gareoung; Yun, Jung‐Ho; Yu, Byung Kyu; Kim, Sung Jin; Ahn, Kyunghan; Rhyee, Jong‐Soo

doi:10.1039/c8ta00381e

Cited by 12 publications

(8 citation statements)

References 50 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…71 Breaking this mirror symmetry would release the topological states. 29,72 Therefore, in our current studied SnTe systems, including various point defects (the Sn vacancy and two kinds of different dopants), the different local geometry distortions introduced those point defects can be easily destroyed the mirror plane symmetry and the corresponding topological states, which is confirmed in the Mg, Mn, or Ca doping in SnTe (Figures S7−S9 in the SI). Thus, the topological SnTe could degrade to the trivial semiconductor under such doping.…”

Section: Methodsmentioning

confidence: 59%

Band Engineering SnTe via Trivalent Substitutions for Enhanced Thermoelectric Performance

et al. 2021

View full text Add to dashboard Cite

SnTe is an attractive candidate for applications as a p-type thermoelectric semiconductor. The pristine SnTe compound exhibits poor thermoelectric performance at high temperatures because of its high hole concentration, small band gap, and large energy difference between the light and heavy bands (ΔE(L – Σ)). To overcome these problems, we investigate band structure changes upon the addition of trivalent dopants based on the tight-binding (TB) model and density functional theory (DFT) calculations. We find that tuning the relative on-site energies of the cation and anion s and p orbitals is a potential route for engineering band convergence. Codoping with Ge in addition to trivalent substitutions further enhances thermoelectric performance. We find that a low concentration of the isovalent Ge as well as As, which also acts as a donor (Sn0.952Ge0.016As0.016Te), induces band convergence (ΔE(L – Σ) = 0.12 eV) and enlarges the band gap (0.20 eV). This band convergence results in a remarkable increase of the peak power factor, while the increased band gap energy suppresses detrimental bipolar effects. We find that the theoretical and experimental results are in good agreement here, and the high power factor (high weighted mobility) can be attributed to the increased band convergence. Our work can efficiently screen the promising trivalent substitutions in SnTe-based materials codoped with Ge and find promising candidates for improved thermoelectric performance.

show abstract

Section: Methodsmentioning

confidence: 59%

Band Engineering SnTe via Trivalent Substitutions for Enhanced Thermoelectric Performance

et al. 2021

View full text Add to dashboard Cite

show abstract

“…In summary, by taking full advantage of both band convergences due to alloying of SnTe and PbTe along with energy filtering of charge carriers, a huge improvement is achieved in the Seebeck coefficient in the composite samples. Further support of energy filtering in improving the Seebeck coefficient of (SnTe) 0.5 (PbTe) 0.5 in addition to band convergence can be witnessed by two facts: (i) the Seebeck coefficient is larger than expected from valence band convergence reported for nearly identical samples Sn 0.7 Pb 0.3 Te, 30 Sn 0.5 Pb 0.5 Te, 31 and Sn 0.97 Bi 0.03 Te-3%PbTe 21 (comparison of Seebeck coefficients is shown in Figure 7c) (ii). The electrical conductivity of (SnTe) 0.5 (PbTe) 0.5 samples is much lower than that of other composite samples (x < 0.5) due to blocking of low-energy charge carriers at the SnTe/PbTe (p/n) interface.…”

Section: Resultsmentioning

confidence: 81%

“…The Sn 0.1 Mn 0.14 Te(Cu 2 Te) 0.05 sample exhibits very high ZT of 1.6 at 900 K (and ZT of 1.2 at 750 K and ZT avg ∼ 0.48 in the range 300–750 K) through integration of band convergence and interstitial defect-mediated low lattice thermal conductivity . It is also important to mention that the previously reported Sn 0.5 Pb 0.5 Te sample having identical composition to the (SnTe) 0.5 (PbTe) 0.5 sample exhibits ZT of 0.02 at 750 K and ZT avg of 0.25 in a temperature range of 300–750 K …”

Section: Resultsmentioning

confidence: 83%

“…(b) Schematic showing relative positions of the conduction band (CB), light-hole valance band (VB L ), and heavy-hole valance band (VB ∑ ) of SnTe and (SnTe) 1– x (PbTe) x ; Δ E is the energy difference between light-hole and heavy-hole valence band edges, and E g is the band gap. (c) Comparison of the Seebeck coefficient of the (SnTe) 0.5 (PbTe) 0.5 sample with the reported literature. ,, …”

Section: Resultsmentioning

confidence: 99%

“…18 It is also important to mention that the previously reported Sn 0.5 Pb 0.5 Te with those of the reported SnTe systems including Sn 0.97 Bi 0.03 Te-3%PbTe, 21 In 0.025 Sn 0.9975 Te, 33 Sn 0.94 Mg 0.06 Te, 34 In 0.015 Sn 0.98 Te 0.85 Se 0.1 , 36 Sn 0.97 Mn 0.03 Te, 35 (Sn 0.91 Mn 0.14 Te)(Cu 2 Te) 0.05 , 18 and Sn 0.5 Pb 0.5 Te. 31 sample having identical composition to the (SnTe) 0.5 (PbTe) 0.5 sample exhibits ZT of 0.02 at 750 K and ZT avg of 0.25 in a temperature range of 300−750 K. 31 Apart from poor thermoelectric performance, the other demerit of SnTe as a thermoelectric material is its brittleness that makes it very fragile for machining or slicing. It can be seen from Figure 10a that the microhardness of pure SnTe was around 57.5 Hv and the incorporation of different volume fractions of the PbTe phase increases the hardness of the SnTe Matrix.…”

Section: Resultsmentioning

confidence: 99%

See 2 more Smart Citations

Band Convergence and Phonon Scattering Mediated Improved Thermoelectric Performance of SnTe–PbTe Nanocomposites

Ahmad

Singh

Bhattacharya

et al. 2020

ACS Appl. Energy Mater.

View full text Add to dashboard Cite

SnTe exhibits poor thermoelectric figure of merit owing to Sn vacancies that give rise to a low p-type Seebeck coefficient and high electrical–thermal conductivities. Here, we reported thermoelectric properties of a composite material synthesized by vacuum hot pressing a mixture of preformed p-type SnTe and n-type PbTe. Detailed characterization revealed that the composite material has SnTe alloyed with PbTe along with n-PbTe nanoinclusions. The cumulative effect of alloying-induced valence band convergence along with energy filtering of charge carriers at the SnTe–PbTe (p–n) interface resulted in an enhanced Seebeck coefficient in the composite material. A significant lowering of thermal conductivity was achieved by phonon scattering at coherent nano p–n junctions and substitution point defects due to alloying. The high Seebeck coefficient along with depressed thermal conductivity in the composite (SnTe)0.5(PbTe)0.5 resulted in the highest figure of merit (ZT) of ∼1.2 at 750 K (i.e., 724% higher compared to pure SnTe) and average ZT of ∼0.5 in a temperature range of 300–750 K. A single-leg thermoelectric power generator fabricated using optimized (SnTe)0.5(PbTe)0.5 showed a conversion efficiency of ∼4.9% for a temperature difference of 400 K.

show abstract

Antisite Defect‐Enhanced Thermoelectric Performance of Topological Crystalline Insulators

Muzaffar

Zhang

Cui

et al. 2020

Adv Funct Materials

View full text Add to dashboard Cite

As the first experimentally established topological crystalline insulator (TCI), SnTe also exhibits superior thermoelectricity upon proper doping; yet to date, whether such doping will preserve or destroy the salient topological properties in achieving outstanding thermoelectric (TE) performance remains elusive. Using first‐principles calculations combined with Boltzmann transport theory, here the elegant role of antisite defect in optimally enhancing the thermopower of SnTe while simultaneously preserving its topological nature is uncovered. It is first shown that SnTe antisite defect effectively induces pronounced variations in the low‐energy density of states rather than rigidly shifting the chemical potential, resulting in a higher Seebeck coefficient and power factor. Next, it is demonstrated that in a wide temperature range, the Seebeck coefficient of antisite‐doped SnTe distinctly outperforms previously identified systems invoking extrinsic dopants. It is further confirmed that such intrinsic antisite doping preserves the nontrivial topology, which in turn favors high electrical conductivity and thermoelectricity. These central findings not only identify an effective and powerful knob in future studies of TE materials, but also help to resolve standing controversies between theory and experiment surrounding the TE performances of both TCIs and topological insulators.

show abstract

Enhancement of thermoelectric performance via weak disordering of topological crystalline insulators and band convergence by Se alloying in Pb_0.5Sn_0.5Te_{1 − x}Se_x

Abstract: This research proposes a new strategy for exploring high-performance thermoelectric materials by weak disordering of topological crystalline Dirac semimetals.

Cited by 12 publications

References 50 publications

Band Engineering SnTe via Trivalent Substitutions for Enhanced Thermoelectric Performance

Band Engineering SnTe via Trivalent Substitutions for Enhanced Thermoelectric Performance

Band Convergence and Phonon Scattering Mediated Improved Thermoelectric Performance of SnTe–PbTe Nanocomposites

Antisite Defect‐Enhanced Thermoelectric Performance of Topological Crystalline Insulators

Contact Info

Product

Resources

About