Abstract:Through coordination of the Seebeck coefficient and carrier concentration in Cu3SnS4, TE performance improves significantly with the ZT value of 0.75 at 790 K.
“…At x = 1.0 the ZT value reaches the highest (ZT = 0.5) at 873 K, 25% higher compared to ZT = 0.4 at x = 0. Although this value is lower that those in other Cu-Sn-S compounds, such as Cu 3 Sn 1.2 S 4 (ZT = 0.75 at 790 K) 7 and Co-Cu 2 SnS 3 (ZT = 0.85 at 723 K) 6 , it still stands out among the highest in the family of Cu 4 Sn 7 S 16 compounds.Figure 6( a ) Total thermal conductivities ( κ ) as a function of temperature for different materials ( x values); ( b ) Lattice thermal conductivities as a function of temperature for different materials ( x values). The solid blue line represents the fitting result using Callaway and Klemens model; ( c ) The values of m * / m e and quality factor B as a function of Se content ( x value); ( d ) TE Figure of merit (ZT) as a function of temperature for different materials ( x values).…”
Section: Resultscontrasting
confidence: 54%
“…For example, the TE figure of merit (ZT) of Zn-doped Cu 2 SnS 3 is 0.58 at 723 K 4 , while that of the pristine Cu 4 Sn 7 S 16 is only 0.2 at 600 K from measurement 1 . In order to improve the TE performance of ternary Cu-Sn-S compounds, we have employed some strategies, such as the band structure engineering in Cu 4 Sn 7 S 16 5 and Cu 2 SnS 3 6 , and the coordination of the Seebeck coefficient and carrier concentration in Cu 3 SnS 4 7 . By employing the above-mentioned approaches, we have achieved remarkable improvements in TE performance, obtaining a ZT value of 0.75 for Cu 3 Sn 1.2 S 4 7 and 0.4 for Cu 4 Sn 7.5 S 16 5 .…”
Section: Introductionmentioning
confidence: 99%
“…In order to improve the TE performance of ternary Cu-Sn-S compounds, we have employed some strategies, such as the band structure engineering in Cu 4 Sn 7 S 16 5 and Cu 2 SnS 3 6 , and the coordination of the Seebeck coefficient and carrier concentration in Cu 3 SnS 4 7 . By employing the above-mentioned approaches, we have achieved remarkable improvements in TE performance, obtaining a ZT value of 0.75 for Cu 3 Sn 1.2 S 4 7 and 0.4 for Cu 4 Sn 7.5 S 16 5 . Nevertheless, a great improvement of the compounds of Cu 4 Sn 7 S 16 family is still necessary.…”
Cu-Sn-S family of compounds have been considered as very competitive thermoelectric candidates in recent years due to their abundance and eco-friendliness. The first-principles calculation reveals that the density of states (DOS) increases in the vicinity of the Fermi level (Ef) upon an incorporation of Se in the Cu4Sn7.5S16−xSex (x = 0–2.0) system, which indicates the occurrence of resonant states. Besides, the formation of Cu(Sn)-Se network upon the occupation of Se in S site reduces the Debye temperature from 395 K for Cu4Sn7S16 (x = 0) to 180.8 K for Cu4Sn7.5S16−xSex (x = 1.0). Although the point defects mainly impact the phonon scattering, an electron-phonon interaction also bears significance in the increase in phonon scattering and the further reducion of lattice thermal conductivity at high temperatures. As a consequence, the resultant TE figure of merit (ZT) reaches 0.5 at 873 K, which is 25% higher compared to 0.4 for Cu4Sn7.5S16.
“…At x = 1.0 the ZT value reaches the highest (ZT = 0.5) at 873 K, 25% higher compared to ZT = 0.4 at x = 0. Although this value is lower that those in other Cu-Sn-S compounds, such as Cu 3 Sn 1.2 S 4 (ZT = 0.75 at 790 K) 7 and Co-Cu 2 SnS 3 (ZT = 0.85 at 723 K) 6 , it still stands out among the highest in the family of Cu 4 Sn 7 S 16 compounds.Figure 6( a ) Total thermal conductivities ( κ ) as a function of temperature for different materials ( x values); ( b ) Lattice thermal conductivities as a function of temperature for different materials ( x values). The solid blue line represents the fitting result using Callaway and Klemens model; ( c ) The values of m * / m e and quality factor B as a function of Se content ( x value); ( d ) TE Figure of merit (ZT) as a function of temperature for different materials ( x values).…”
Section: Resultscontrasting
confidence: 54%
“…For example, the TE figure of merit (ZT) of Zn-doped Cu 2 SnS 3 is 0.58 at 723 K 4 , while that of the pristine Cu 4 Sn 7 S 16 is only 0.2 at 600 K from measurement 1 . In order to improve the TE performance of ternary Cu-Sn-S compounds, we have employed some strategies, such as the band structure engineering in Cu 4 Sn 7 S 16 5 and Cu 2 SnS 3 6 , and the coordination of the Seebeck coefficient and carrier concentration in Cu 3 SnS 4 7 . By employing the above-mentioned approaches, we have achieved remarkable improvements in TE performance, obtaining a ZT value of 0.75 for Cu 3 Sn 1.2 S 4 7 and 0.4 for Cu 4 Sn 7.5 S 16 5 .…”
Section: Introductionmentioning
confidence: 99%
“…In order to improve the TE performance of ternary Cu-Sn-S compounds, we have employed some strategies, such as the band structure engineering in Cu 4 Sn 7 S 16 5 and Cu 2 SnS 3 6 , and the coordination of the Seebeck coefficient and carrier concentration in Cu 3 SnS 4 7 . By employing the above-mentioned approaches, we have achieved remarkable improvements in TE performance, obtaining a ZT value of 0.75 for Cu 3 Sn 1.2 S 4 7 and 0.4 for Cu 4 Sn 7.5 S 16 5 . Nevertheless, a great improvement of the compounds of Cu 4 Sn 7 S 16 family is still necessary.…”
Cu-Sn-S family of compounds have been considered as very competitive thermoelectric candidates in recent years due to their abundance and eco-friendliness. The first-principles calculation reveals that the density of states (DOS) increases in the vicinity of the Fermi level (Ef) upon an incorporation of Se in the Cu4Sn7.5S16−xSex (x = 0–2.0) system, which indicates the occurrence of resonant states. Besides, the formation of Cu(Sn)-Se network upon the occupation of Se in S site reduces the Debye temperature from 395 K for Cu4Sn7S16 (x = 0) to 180.8 K for Cu4Sn7.5S16−xSex (x = 1.0). Although the point defects mainly impact the phonon scattering, an electron-phonon interaction also bears significance in the increase in phonon scattering and the further reducion of lattice thermal conductivity at high temperatures. As a consequence, the resultant TE figure of merit (ZT) reaches 0.5 at 873 K, which is 25% higher compared to 0.4 for Cu4Sn7.5S16.
“…Thus, exploring new TE materials from the viewpoints of low-cost, low-toxicity and earth-abundance is drawing increasing attention. In recent years, Cu-based sulfides, such as Cu 12 Sb 4 S 13 , [6][7][8] Cu 3 SbS 4 , [9][10][11] CuSbS 2 , 12,13 CuCr 2 S 4 , 14 Cu 2 SnS 3 , 15,16 Cu 3 SnS 4 , 17 CuFeS 2 , [18][19][20][21] Cu 5 FeS 4 , 22 Cu 6 Fe 2 SnS 8 , 23 have been recognized as interesting and promising TE materials. Among these compounds, Cu 3 SbS 4 has a simple zinc-blende related structure with a moderate band gap of B0.47 eV.…”
“…Indeed, as shown in Figure 6, transport properties of pure SnS and Na 0.02 Sn 0.98 S crystals displayed a strongly anisotropic character, with the electrical resistivity along the a-axis being much higher than that along the b-axis and the c-axis. Of all the single crystalline SnS samples, the maximum [34,38,39,[42][43][44][45][46][47] in the temperatures range from ≈300 to ≈900 K. The detail methods [48] are displayed in the Supporting Information. Additionally, the thermal conductivity along the a-axis for both SnS and Na 0.02 Sn 0.98 S crystals was lower than the conductivity along the b-axis and the c-axis.…”
the total thermal conductivity consisting of the lattice part (κ L ) and the electronic part (κ e ). [6] Some of these parameters (S, ρ, and κ e ), however, are mutually interdependent and strongly coupled by way of the carrier concentration, making it difficult to attain high TE performance (zT) without making some compromise. Fortunately, in the past decade, several general strategies have been developed to achieve high zT in various materials. [7,8] Lowering the lattice thermal conductivity (κ L ), which is relatively independent of other parameters, is a comparatively easy method. Other well-documented methods for enhancing phonon scattering include nanostructuring, [9][10][11] dislocations, [12,13] point defects, [14][15][16][17] and strong lattice anharmonicity. [18][19][20] Additional strategies to boost the power factor (S 2 ρ −1 ) include carrier concentration optimization, [21,22] band convergence, [23,24] and creating band resonance levels. [25] Typically, practical TE materials are polycrystalline structures with grain boundaries that help to maintain a low lattice thermal conductivity but inevitably also degrade the charge carrier mobility. Recently, bulk SnSe [26][27][28][29][30] and In 4 Se 3[31] single crystals have attracted increasing amounts of attention. The layered structure and strong lattice anharmonicity of these materials cause ultralow lattice thermal conductivity, independent of grain boundary phonon scattering. Therefore, such single crystalline compounds are expected to yield superior performance as both high mobility and low lattice thermal conductivity can be maintained simultaneously. For instance, the ultrahigh zT of Lead-free tin sulfide (SnS), with an analogous structure to SnSe, has attracted increasing attention because of its theoretically predicted high thermoelectric performance. In practice, however, polycrystalline SnS performs rather poorly as a result of its low power factor. In this work, bulk sodium (Na)-doped SnS single crystals are synthesized using a modified Bridgman method and a detailed transport evaluation is conducted. The highest zT value of ≈1.1 is reached at 870 K in a 2 at% Na-doped SnS single crystal along the b-axis direction, in which high power factors (2.0 mW m −1 K −2 at room temperature) are realized. These high power factors are attributed to the high mobility associated with the single crystalline nature of the samples as well as to the enhanced carrier concentration achieved through Na doping. An effective single parabolic band model coupled with first-principles calculations is used to provide theoretical insight into the electronic transport properties. This work demonstrates that SnS-based single crystals composed of earth-abundant, low-cost, and nontoxic chemical elements can exhibit high thermoelectric performance and thus hold potential for application in the area of waste heat recovery.
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