Realizing high thermoelectric performance in GeTe through decreasing the phase transition temperature <i>via</i> entropy engineering

Qiu, Yuting; Jin, Yang; Wang, Dongyang; Guan, Min; He, Wei; Peng, Shang; Liu, Ruiheng; Gao, Xiang; Zhao, Li‐Dong

doi:10.1039/c9ta10963c

“…Where NA, 𝑘 𝐵 and 𝑥 𝑖 being the Avogadro number, Boltzmann constant, and the mole fraction of each of the elements, respectively. The entropy estimation method employed here is similar to previous reports [53][54][55] . The ∆𝑆 for all samples in this work ranges from 5.76 J/molK for pristine GeTe to 10.47 J/molK for Ge0.39Sn0.39Bi0.02Sb0.20Te.…”

Section: Resultsmentioning

confidence: 93%

Tailoring the phase transition temperature to achieve high-performance cubic GeTe-based thermoelectrics

Suwardi

¹

,

Cao

²

,

Hu

³

et al. 2020

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“…The data for GeTe, Ge 0.95 Mg 0.05 Te, and typical doped GeTe-based compounds (dashed lines) are included for comparison. [12][13][14][16][17][18]20,36,37,39] neously distributed in the matrix without forming any secondary phases. These results prove that Bi and Mg successfully enter into the lattice of GeTe.…”

Section: Resultsmentioning

confidence: 99%

Ultralow Lattice Thermal Conductivity and Superhigh Thermoelectric Figure‐of‐Merit in (Mg, Bi) Co‐Doped GeTe

Xing

¹

,

Zhu

²

,

Song

³

et al. 2021

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zT = S 2 σT/κ, where S is the Seebeck coefficient, σ is the electrical conductivity, T is the absolute temperature, and κ is the thermal conductivity consisting of the lattice thermal conductivity (κ L ) and carrier thermal conductivity (κ c ). [3] Doping external elements is a routine but effective approach to improve zT because it can tune carrier concentration or band structure to optimize PF (S 2 σ) and introduce point defects to suppress κ L . [4][5][6][7][8] However, the application of this approach highly relies on the kind and solution limit of the external elements in the host lattice. Among the numerous TE materials reported so far, GeTe is a special one because its lattice can accommodate many external elements with relatively large solution limits. Typical dopants are Sb (≈10% at Ge-sites), Bi (≈10% at Ge-sites), Pb (≈10% at Ge-sites), and Mn (>50% at Ge-sites). [9][10][11][12][13][14] Upon introducing these dopants, the κ L of GeTe can be reduced from 3.0 to around 1.0 W m −1 K −1 at 300 K. Moreover, the lattice of GeTe can simultaneously accommodate two or multiple kinds of external elements with distinct atomic mass and radius, such as (Mn, Sb), (Mn, Bi), (Cu, Sb), (In, Sb), (In, Bi), (Cr, Sb), (Ti, Sb), (Pb, Sb), and (Pb, Bi), which can further reduce the κ L to as low as 0.5 W m −1 K −1 . [15][16][17][18][19][20][21][22][23][24][25] Combining the optimized electrical transport properties by these external elements, GeTe-based compounds demonstrate high zTs in the intermediate temperature range. Among the single-doped GeTe-based compounds, Ge 0.9 Sb 0.1 Te and Ge 0.9 Bi 0.06 Te demonstrate zTs above 1.5 at 700 K. [9,10] Among the double-or multiple-doped GeTe-based compounds, Ge 0.89 Sb 0.1 In 0.01 Te, Ge 0.89 Cu 0.06 Sb 0.08 Te, Ge 0.86 Pb 0.1 Bi 0.04 Te, and Ge 0.9 Cd 0.05 Bi 0.05 Te demonstrate high zTs exceeding the level of 2.0. [15][16][17]26] Currently, GeTe-based compounds are among the best TE materials in thermoelectrics.The κ L reduction in doped GeTe-based compounds are mainly caused by the strain field and mass fluctuations introduced by the dopants. Theoretically, κ L is given by [27,28] High-efficiency thermoelectric (TE) technology is determined by the performance of TE materials. Doping is a routine approach in TEs to achieve optimized electrical properties and lowered thermal conductivity. However, how to choose appropriate dopants with desirable solution content to realize high TE figure-of-merit (zT) is very tough work. In this study, via the use of large mass and strain field fluctuations as indicators for low lattice thermal conductivity, the combination of (Mg, Bi) in GeTe is screened as very effective dopants for potentially high zTs. In experiments, a series of (Mg, Bi) co-doped GeTe compounds are prepared and the electrical and thermal transport properties are systematically investigated. Ultralow lattice thermal conductivity, about 0.3 W m −1 K −1 at 600 K, is obtained in Ge 0.9 Mg 0.04 Bi 0.06 Te due to the introduced large mass and strain field fluctuations by (Mg, Bi)...

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“…The chalcogenide compounds have attracted great interest owing to their high thermoelectric performance, microelectronics, electronic and optical properties 1 – 5 . For implementations in all industrial sectors, chalcogenides are presently quite interesting 6 .…”

Section: Introductionmentioning

confidence: 99%

Ab initio prediction of semiconductivity in a novel two-dimensional Sb2X3 (X= S, Se, Te) monolayers with orthorhombic structure

Bafekry

¹

,

Mortazavi

²

,

Fadlallah

³

et al. 2021

Sci Rep

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Abstract$$\hbox {Sb}_2\hbox {S}_3$$ Sb 2 S 3 and $$\hbox {Sb}_2\hbox {Se}_3$$ Sb 2 Se 3 are well-known layered bulk structures with weak van der Waals interactions. In this work we explore the atomic lattice, dynamical stability, electronic and optical properties of $$\hbox {Sb}_2\hbox {S}_3$$ Sb 2 S 3 , $$\hbox {Sb}_2\hbox {Se}_3$$ Sb 2 Se 3 and $$\hbox {Sb}_2\hbox {Te}_3$$ Sb 2 Te 3 monolayers using the density functional theory simulations. Molecular dynamics and phonon dispersion results show the desirable thermal and dynamical stability of studied nanosheets. On the basis of HSE06 and PBE/GGA functionals, we show that all the considered novel monolayers are semiconductors. Using the HSE06 functional the electronic bandgap of $$\hbox {Sb}_2\hbox {S}_3$$ Sb 2 S 3 , $$\hbox {Sb}_2\hbox {Se}_3$$ Sb 2 Se 3 and $$\hbox {Sb}_2\hbox {Te}_3$$ Sb 2 Te 3 monolayers are predicted to be 2.15, 1.35 and 1.37 eV, respectively. Optical simulations show that the first absorption coefficient peak for $$\hbox {Sb}_2\hbox {S}_3$$ Sb 2 S 3 , $$\hbox {Sb}_2\hbox {Se}_3$$ Sb 2 Se 3 and $$\hbox {Sb}_2\hbox {Te}_3$$ Sb 2 Te 3 monolayers along in-plane polarization is suitable for the absorption of the visible and IR range of light. Interestingly, optically anisotropic character along planar directions can be desirable for polarization-sensitive photodetectors. Furthermore, we systematically investigate the electrical transport properties with combined first-principles and Boltzmann transport theory calculations. At optimal doping concentration, we found the considerable larger power factor values of 2.69, 4.91, and 5.45 for hole-doped $$\hbox {Sb}_{{2}}\hbox {S}_{{3}}$$ Sb 2 S 3 , $$\hbox {Sb}_{{2}}\hbox {Se}_{{3}}$$ Sb 2 Se 3 , and $$\hbox {Sb}_{{2}}\hbox {Te}_{{3}}$$ Sb 2 Te 3 , respectively. This study highlights the bright prospect for the application of $$\hbox {Sb}_2\hbox {S}_3$$ Sb 2 S 3 , $$\hbox {Sb}_2\hbox {Se}_3$$ Sb 2 Se 3 and $$\hbox {Sb}_2\hbox {Te}_3$$ Sb 2 Te 3 nanosheets in novel electronic, optical and energy conversion systems.

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Realizing high thermoelectric performance in GeTe through decreasing the phase transition temperature via entropy engineering

Abstract: Entropy engineering is one of the powerful approaches to suppress phase transitions.

Cited by 116 publications

References 51 publications

Tailoring the phase transition temperature to achieve high-performance cubic GeTe-based thermoelectrics

Tailoring the phase transition temperature to achieve high-performance cubic GeTe-based thermoelectrics

Ultralow Lattice Thermal Conductivity and Superhigh Thermoelectric Figure‐of‐Merit in (Mg, Bi) Co‐Doped GeTe

Ab initio prediction of semiconductivity in a novel two-dimensional Sb2X3 (X= S, Se, Te) monolayers with orthorhombic structure

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