On the Band Gap of AgSbSe2

Ragimov, S. S.; Bagiev, V. E.; Alieva, A. I.; Saddinova, A. A.

doi:10.1134/s106378262104014x

Cited by 4 publications

(4 citation statements)

References 31 publications

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“…However, experimental optical measurements for absorption edge indicate a much larger E g value of ~0.32 eV. [54] Despite the fact that E g is usually underestimated by density functional theory (DFT) calculations, this gap discrepancy cannot be recovered by the modified Becke Johnson functional (mBJ), or the Perdew-Burke-Ernzerhof (PBE) + U methods, or full relativistic calculations. [55] The valence band of AgSbSe 2 is composed of multiple pockets at the Χ-point of the Brillouin zone, while the conduction band minimum is located at L symmetry point, as shown in Figure 1b.…”

Section: Electronic Band Structurementioning

confidence: 99%

“…By use of Arrhenius law, an indirect narrow band gap ( E g) ∼0.03 eV [45] is obtained for AgSbSe 2 . However, experimental optical measurements for absorption edge indicate a much larger E g value of ∼0.32 eV [54] . Despite the fact that E g is usually underestimated by density functional theory (DFT) calculations, this gap discrepancy cannot be recovered by the modified Becke Johnson functional (mBJ), or the Perdew‐Burke‐Ernzerhof (PBE)+U methods, or full relativistic calculations [55] .…”

Section: Electronic Band Structurementioning

confidence: 99%

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Advances and Challenges of AgSbSe₂‐based Thermoelectric Materials

2022

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Thermoelectric materials have aroused wide attention because of the capability to directly convert heat into electricity. AgSbSe2 is a structural analogue of PbTe but does not contain toxic element Pb or expensive element Te. Besides, it possesses both high Seebeck coefficient and inherently low thermal conductivity, making AgSbSe2 a competitive candidate for mid‐temperature thermoelectric power generation. This review summarizes the most recent updates of AgSbSe2‐based thermoelectric compounds. It starts with a general introduction of the crystal and electronic band structures of pristine AgSbSe2 with particular emphasis on the debate about whether cations arrangement is ordered or disordered. We then discuss why AgSbSe2 displays glass‐like heat conduction despite its crystalline nature. Subsequently, the strategies of boosting the electrical properties of the titled compound are elaborated. Finally, we point out the challenges and outlooks toward the future development of AgSbSe2‐based thermoelectric materials.

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Section: Electronic Band Structurementioning

confidence: 99%

Section: Electronic Band Structurementioning

confidence: 99%

Advances and Challenges of AgSbSe₂‐based Thermoelectric Materials

2022

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“…In PbSe‐AgSbSe 2 , similar lattice reduction and band gap enlargement have been observed. [ 33 ] A recent report shows that AgSbSe 2 has a narrow band gap ≈0.35 eV, [ 45 ] and therefore the enlarged band gap in PbSe‐AgSbSe 2 cannot be explained by the Vegard's law. Meanwhile, previous study on SnTe‐AgSbSe 2 did not find the enlargement of band gap.…”

Section: Resultsmentioning

confidence: 99%

Giant Band Convergence and High Thermoelectric Performance in n‐Type PbSe Induced by Spin‐Orbit Coupling

Cai,

Wang,

Zhuang

et al. 2024

Adv Funct Materials

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An ideal thermoelectric material requires the multi‐valley and strong dispersion band structure, for relieving the competition between thermopower and electrical conductivity, whereas the two features barely coexist in natural compounds. Here, the significantly improved thermoelectric performance in n‐type PbSe‐xAgSbS2 with the purposefully renormalized conduction band structure is reported. It is shown that the strong spin‐orbit coupling effect splits the single valley at “L” point into three individuals delicately, as the Dirac point is shifted away from the high symmetry point by the decreasing lattice constant. Compared with the common PbSe‐based compounds, the renormalized system exhibits a range of distinctive properties, such as the 2–3 times larger band gap, 5–10 times lower optimal carrier concentration, and weakly temperature‐dependent Seebeck coefficient. Owing to the achieved giant band convergence and the low thermal conductivity, a high peak zT of 1.75 at 850 K and an outstanding average zT of 1.04 are obtained. Furthermore, the mechanical property and thermal stability of PbSe are considerably improved for the introduced high entropy effect and lattice shrinkage. This study reveals the remarkable impact of spin‐orbit coupling on thermoelectric performance, and suggests that the optimized PbSe material holds great promise for practical applications.

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“…The determined band gap (E g ) is close to 0 eV, lower than the measured value of 0.32 eV for AgSbSe 2 , but consistent with previous DFT calculations. 67,68 Although E g is underestimated, DFT calculations still provide insights into the evolution of band structures upon Sn doping. In the band structure of AgSbSe 2 , there exist two valence band edges at the W and X points, separated by a small energy offset, which can potentially contribute to carrier transport.…”

Section: Resultsmentioning

confidence: 99%

Surface Chemistry and Band Engineering in AgSbSe₂: Toward High Thermoelectric Performance

Liu

Wan

et al. 2023

ACS Nano

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AgSbSe 2 is a promising thermoelectric (TE) ptype material for applications in the middle-temperature range. AgSbSe 2 is characterized by relatively low thermal conductivities and high Seebeck coefficients, but its main limitation is moderate electrical conductivity. Herein, we detail an efficient and scalable hot-injection synthesis route to produce AgSbSe 2 nanocrystals (NCs). To increase the carrier concentration and improve the electrical conductivity, these NCs are doped with Sn 2+ on Sb 3+ sites. Upon processing, the Sn 2+ chemical state is conserved using a reducing NaBH 4 solution to displace the organic ligand and anneal the material under a forming gas flow. The TE properties of the dense materials obtained from the consolidation of the NCs using a hot pressing are then characterized. The presence of Sn 2+ ions replacing Sb 3+ significantly increases the charge carrier concentration and, consequently, the electrical conductivity. Opportunely, the measured Seebeck coefficient varied within a small range upon Sn doping. The excellent performance obtained when Sn 2+ ions are prevented from oxidation is rationalized by modeling the system. Calculated band structures disclosed that Sn doping induces convergence of the AgSbSe 2 valence bands, accounting for an enhanced electronic effective mass. The dramatically enhanced carrier transport leads to a maximized power factor for AgSb 0.98 Sn 0.02 Se 2 of 0.63 mW m −1 K −2 at 640 K. Thermally, phonon scattering is significantly enhanced in the NC-based materials, yielding an ultralow thermal conductivity of 0.3 W mK −1 at 666 K. Overall, a record-high figure of merit (zT) is obtained at 666 K for AgSb 0.98 Sn 0.02 Se 2 at zT = 1.37, well above the values obtained for undoped AgSbSe 2 , at zT = 0.58 and state-of-art Pb-and Te-free materials, which makes AgSb 0.98 Sn 0.02 Se 2 an excellent p-type candidate for medium-temperature TE applications.

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On the Band Gap of AgSbSe2

Cited by 4 publications

References 31 publications

Advances and Challenges of AgSbSe₂‐based Thermoelectric Materials

Advances and Challenges of AgSbSe₂‐based Thermoelectric Materials

Giant Band Convergence and High Thermoelectric Performance in n‐Type PbSe Induced by Spin‐Orbit Coupling

Surface Chemistry and Band Engineering in AgSbSe₂: Toward High Thermoelectric Performance

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On the Band Gap of AgSbSe2

Cited by 4 publications

References 31 publications

Advances and Challenges of AgSbSe2‐based Thermoelectric Materials

Advances and Challenges of AgSbSe2‐based Thermoelectric Materials

Giant Band Convergence and High Thermoelectric Performance in n‐Type PbSe Induced by Spin‐Orbit Coupling

Surface Chemistry and Band Engineering in AgSbSe2: Toward High Thermoelectric Performance

Contact Info

Product

Resources

About

Advances and Challenges of AgSbSe₂‐based Thermoelectric Materials

Advances and Challenges of AgSbSe₂‐based Thermoelectric Materials

Surface Chemistry and Band Engineering in AgSbSe₂: Toward High Thermoelectric Performance