Structural Modularization of Cu2Te Leading to High Thermoelectric Performance near the Mott-Ioffe-Regel Limit

doi:10.21203/rs.3.rs-699516/v1

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Structural Modularization of Cu₂Te Leading to High Thermoelectric Performance near the Mott-Ioffe-Regel Limit

https://doi.org/10.21203/rs.3.rs-699516/v1

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To date, thermoelectric materials research stays focused on optimizing the material’s band edge details and disfavors low mobility. Here, we shifts the paradigm from the band edge to the mobility edge, exploring high thermoelectricity near the border of band conduction and hopping. Through co-alloying iodine and sulfur, we modularize the plain crystal structure of liquid-like thermoelectric material Cu₂Te with mosaic nanodomains and the highly size mismatched S/Te sublattice that chemically quenches the Cu sublattice and drives the electronic states from itinerant to localized. A state-of-the-art figure of merit of 1.4 is obtained at 850 K for Cu₂(S_0.4I_0.1Te_0.5); and remarkably, it is achieved near the Mott-Ioffe-Regel limit unlike mainstream thermoelectric materials that are band conductors. Broadly, pairing structural modularization with the high performance near the Mott-Ioffe-Regel limit paves an important new path towards the rational design of high-performance thermoelectric materials.

Thermoelectric (TE) material-based energy conversion technology has attracted increasing global attention in virtue of the technical merits such as no moving parts, no greenhouse emission, noiseless, friendliness for miniaturization, and reliability.^1–4 Based on the Seebeck and Peltier effects, thermoelectricity enables a direct energy conversion between temperature difference and electricity.^{5, 6} The performance of a TE material is primarily gauged by the material’s figure of merit, zT = S²T/ρκ, where S is the Seebeck coefficient, T is the absolute temperature, ρ is the electrical resistivity, and κ is the total thermal conductivity (consisting of the lattice thermal conductivity κ_L and the electronic thermal conductivity κ_E).

Electronic Materials and Devices

Catalysis

Photonics/optics

Cu2Te

thermoelectric materials

conductivity

Thermoelectric (TE) material-based energy conversion technology has attracted increasing global attention in virtue of the technical merits such as no moving parts, no greenhouse emission, noiseless, friendliness for miniaturization, and reliability.^1-4 Based on the Seebeck and Peltier effects, thermoelectricity enables a direct energy conversion between temperature difference and electricity.^{5, 6} The performance of a TE material is primarily gauged by the material’s figure of merit, zT = S²T/ρκ, where S is the Seebeck coefficient, T is the absolute temperature, ρ is the electrical resistivity, and κ is the total thermal conductivity (consisting of the lattice thermal conductivity κ_L and the electronic thermal conductivity κ_E).

In view of the adversely inter-dependent S, ρ and κ, attaining high zT values entails hierarchical diverse structure-functional modules in the material. To this end, “hybrid crystal” or “structural modularity” is preferred in TE materials research as these complex materials are composed of building modules with distinct compositions and functions,^{7, 8} through which the adverse coupling of S, ρ and κ can be eased and tuned selectively. Layered cobalt oxides,⁹ filled skutterudites,¹⁰ and liquid-like TE materials¹¹ are good examples of hybrid crystals as they contain specific structural-functional modules such as the sublattices respectively undertaking charge conduction and phonon scattering.

The structural hybridity or modularity doesn’t need to be native, extrinsic defects act as endowed structural-functional modules. For example, static point defects and mobile ions,^11-14 nanoscale lattice strains, and micro-scale grain boundaries jointly suppress the lattice thermal conductivity.^15-17 Meanwhile, the doping induced resonant electronic states,¹⁸ the energy filtering effect at grain boundary,¹⁹ and the doping regulated carrier concentration optimization and band convergence enhance the electronic transport properties via optimizing the material’s electron band structure, especially the details of band edge.^{20, 21} To date, the state-of-the-art TE materials are band conductors with decent carrier concentrations on the order of 10 cm² V^-1 s^-1and above.

An important question follows directly, can we utilize doping to structurally modularize an otherwise plain crystal structure? Further, as structural modularization degrades the carrier mobility, a key ingredient of the TE quality factor,²² would such structurally modularized low-mobility materials be able to yield state-of-the-art TE performance? The answers are potentially paradigm shifting.

Here we present a case study in copper telluride (Cu_2-xTe), a liquid-like TE material known for its complex atomic order-disorder of Cu ions in a number of structural polymorphs.^23-26 The nearly degenerate crystal structures make Cu_2-xTe a good material template to implement structural modularization and study the pertinent effects on the TE properties. Compared to other TE materials, doped copper tellurides have fairly high carrier concentrations in the range of 2 ~ 4 × 10²¹ cm^-3, and the room temperature carrier mobilities are in the range of 15 ~ 30 cm²V^-1s^-1,^23-26 not far from the Mott-Ioffe-Regel limit.^{27, 28} Through co-alloying with iodine and sulfur, we structurally-functionally modularize Cu₂_-xTe with (i) the atomic-scale aliovalent I dopants on the Te sites that act as effective donors to reduce the hole concentration and scatter the heat-carrying phonons at elevated temperatures; (ii) the highly size mismatched yet crystalline S/Te sublattice that chemically quenches the Cu sublattice and also drives the electronic states from itinerant to localized with increasing S content; and (iii) the mosaic nanodomains that joint force with other types of defects to suppress the thermal conductivity. A greatly enhanced Seebeck coefficient (260 mV K^-1 at 850 K) and a record-high figure of merit (1.4 at 850 K) in Cu₂Te_0.5I_0.1S_0.4 (cf. Figure 1a) are attained near the Mott-Ioffe-Regel limit, which delimits band conduction and hopping, in contrast to the state-of-the-art TE materials that are well-established band conductors (cf. Figure 1b).

Figure 2a displays the room-temperature powder X-ray diffraction patterns (PXRD) of Cu₂Te_1-xI_x (x = 0.0, 0.05, and 0.1) and Cu₂Te_0.9-yI_0.1S_y (y = 0.1, 0.2, 0.3, 0.4, and 0.5) samples. The crystal structure of pristine Cu₂Te tends to be structurally polymorphic, in accordance with literatures.^{24, 25} Upon doping I on the Te site (denoted by the x ratio), the XRD peaks are readily indexed to a hexagonal structure (space group P6/mmm). The maximum solubility of I in Cu₂Te is found to be around 10% (cf. Figure S1), below which I enters the Te site and serves as a substitutional point defect and also an effective donor. The lattice parameters remain unchanged upon I doping as the atomic size of I is close to that of Te (cf. Figure 2b). In the presence of I, further alloying S on the Te site (denoted by the y ratio), the (001) peak at 2θ = 12° gradually diminishes with increasing y value and finally disappears at y ≥ 0.3, indicating the structural transition from the space group P6/mmm to P6₃/mmc. The linearly decreasing lattice parameter with increasing S ratio obeys the Vegard’s law, agreeing with the substitution of S on the Te sites.

The solubility of S in Cu₂Te is much larger than that of I in Cu₂Te even though the atomic radius of I (1.40 Å) is closer to Te (1.40 Å) than that of S (1.00 Å). Notably, hump features are clearly detected in the XRD patterns of the samples with high S content (x≥0.3), pointing toward the presence of amorphous component in the relevantsamples (cf. Figure 2a). Such observation is well consistent with our previous study that the Cu sublattice is chemically quenched into an amorphous state by the anionic S/Te sublattice with large atomic size mismatch.^{8, 45} The atom probe tomography (APT) analysis in Figure 2c confirms the homogeneity of all elements down to tens-of-nanometers scale. Furthermore, the imaging contrast variations of the atomically resolved high angle annular dark field (HAADF) image (cf. Figure S2) indicate the uniform distribution of Te, I, and S in the anionic framework. Cu ions are hard to discern due to the disordered nature. All these results unequivocally corroborate that I and S randomly substitute Te and exist as point defects.

Other than the aforementioned atomic scale defects and size mismatched S/Te sublattice, the I/S co-doped samples contain nanoscale mosaic microstructures and amorphous component on the Cu sublattice. Figures 3b shows the selected-area electron diffraction (SAED) pattern of the red circle area in Figure 3a along the [0001] zone axis. Closer scrutiny reveals that the diffraction patterns are not sharp dots but short arc-like Bragg streaks, a signature of diffuse diffraction and reminiscent of the SAED pattern of mosaic nanodomains with low-angle domain boundaries reported by He et al. in Cu₂Te_1-yS_y samples. ^{29, 46} This is further corroborated by the bright-field and dark-field images in Figure 3c-f. The nano-domains with low-angle boundaries lead to the formation of fluctuated imaging contrast in bright-field and dark-field images. The size of each domain is only around 10-30 nm, which plays a key role in scattering mid-to-long wavelength heat-carrying phonons. Besides, the diffraction rings in Figure 3b indicate the presence of amorphous component, i.e. glass-like Cu sublattice in Cu₂Te_0.9-yI_0.1S_y, in accordance with our XRD results.

The interplay between the I dopants and S dopants has an interesting effect on the carrier concentration. Doping iodine into Cu₂Te, the hole concentration (p) is decreased from (2-3) × 10²¹ cm^-3 to 1.3 × 10²¹ cm^-3 for Cu₂Te_0.9I_0.1 (cf. Figure 4a and Figure S3a) as iodine acts as a donor. With further alloying S in the I-doped Cu₂Te_0.9-yI_0.1S_y, the hole concentrations are barely changed. This is somewhat a surprise as the early study showed that the p was gradually reduced with increasing S alloying content when S is solely alloyed in Cu₂Te_1-yS_y (cf. Figure 4a).^{45, 47} To probe the interplay between iodine doping and sulfur doping, we performed defect formation energy (E_v) calculations to find out what occurs upon S alloying with or without I doping. A 2×2×2 Cu₂Te supercell containing 48 atoms (i.e. Cu₃₂Te₁₆) was used to simulate the alloyed system (cf. Figure 4b). The Cu vacancy (V_Cu) formation energy (E_v) for Cu₃₂Te₁₆ (i.e. Cu₂Te) is around 0.08 eV (cf. Figure 4c). Substituting Te by S, the E_v of V_Cu is increased to 0.18-0.29 eV, and thus the formation of V_Cu is substantially suppressed. Using extrinsic point defects to regulate the formation energy and thus the concentration of native point defects is a routine to tune the electrical properties of narrow bandgap semiconductors by isoelectronic doping.^{20, 48} The change of E_v of V_Cu explains the observed reduction of p in S alloyed Cu₂Te_1-yS_y. Substituting Te by I, the E_v values for V_Cu1, V_Cu2, and V_Cu4 are substantially enhanced but the E_v for the Cu bonded to I, namely, V_Cu3, is reduced to negative. It is hard to conclude on the trend of the total Cu vacancy concentration upon iodine doping. Nonetheless, the overall carrier concentration should be somewhat reduced as iodine dopants serve as donors. Co-alloying Cu₂Te with both S and I, the variations of E_v of V_Cu are found to be similar to those of sole I-doping (cf. Figure 4c). With regard to the net carrier concentration variation, S alloying seems to play a minor role on the formation of V_Cu in the presence of I. As a result, the carrier concentration is expected to be barely changed in Cu₂Te_0.9-yI_0.1S_y with increasing S content, agreeing with what we experimentally observed (cf. Figure 4a).

Figure 4d shows the room temperature carrier mobility (μ) of Cu₂Te_1-xI_x, Cu₂Te_0.9-yI_0.1S_y, and Cu₂Te_1-yS_y as a function of I/S content. Upon doping I, the μ of Cu₂Te is largely suppressed due to the enhanced ionized-impurity scattering. When alloying S in Cu₂Te_0.9I_0.1while fixing the I ratio at 0.1, the μ is further reduced by nearly one order of magnitude. The minimum μ at room temperature of the y = 0.4 sample is only 0.8 cm² V^-1 s^-1, which is lower than the Mott-Ioffe-Regel (MIR) limit (1.3 cm² V^-1 s^-1).^{27, 28} Though we were unable to measure the carrier mobility above room temperature due to general technical restrictions and the already ultralow mobility values, the mobility values of the high S-ratio samples are expected to be near, if not lower than, the MIR limit at temperatures where these samples attain their maximum zT values. By contrast, the state-of-the-art TE materials are featured by well-established band conduction with the carrier mobilities on the order of 10² cm²V^-1s^-1 and above. The μ of y ≤ 0.3 samples exhibit weak temperature dependence, in contrast, the μ of y = 0.4 sample exhibits a slight yet clear positive slope with increasing temperature from 25 K to 300 K (cf. Figure S3b). Since the I content stays the same in the samples studied, ionized impurity scattering alone can’t be the cause of the positive slope of μ vs T for the y = 0.4 sample. The high magnitude on the order of 10²¹ cm^-3and the weak temperature dependence of the carrier concentration (Figure S3a) exclude the Mott localization and band gap opening as the main cause of the S-content driven resistivity and Seebeck coefficient behavior changeovers shown in Figure 4a and 4b.

Hence, the phonon-assisted hopping mechanism is a plausible scenario, and the reduction of μ is mainly ascribed to the S-alloying induced disorder and Anderson localization.^{45, 49-51} The electronic conduction is dominated by hopping conduction (band conduction) when the Fermi level is in localized state (extended state).⁵² With increasing S content, the degree of disorder is increased, the electron transport behavior is thus driven from itinerant conduction to hopping conduction, leading to a large reduction of μ. On the other hand, the electronic conduction of a material governed by a mobility edge is expected to have strong TE response, i.e., large Seebeck coefficient, on the insulating side of the mobility edge.⁵³ Indeed, the room temperature Seebeck coefficients of the S-alloyed samples studied herein are in the range of 40-120 μV K^-1 (cf. Figure 4e) at high carrier concentrations on the order of 10²¹ cm^-3 (cf. Figure 4a), which is hard to explain by band conduction and points towards hopping conduction.

The Seebeck coefficient S is significantly enhanced upon I doping and/or S alloying. Specifically, a maximum S of 119 μV K^-1 at room temperature is obtained for Cu₂Te_0.4I_0.1S_0.5, which is four times larger than that of Cu₂Te and three times higher than that of S-free Cu₂Te_0.9I_0.1 (cf. Figure 4e). Figure 4f shows the Seebeck coefficient as a function of carrier concentration at room temperature for Cu₂Te_1-xI_x, Cu₂Te_0.9-yI_0.1S_y, and Cu₂Te_1-yS_y. Though the electronic conduction in the sample studied is complex, the Pisarenko plot gives some insights into the microscopic conduction mechanism. Specifically, the data of I-doped samples lie around the Pisarenko plot with effective mass of 2.1 m_e, suggesting that I doping shifts the Fermi level without obviously altering the band structure. In contrast, the S-alloyed samples clearly show much larger Seebeck coefficient than the calculated Pisarenko plot. For Cu₂Te_1-yS_y: the Seebeck coefficient S are improved by nearly three times while the carrier concentration is reduced to half the value of Cu₂Te. For the Cu₂Te_0.9-yI_0.1S_ysamples, the Seebeck coefficients S are also significantly increased after alloying S although the carrier concentrations are barely changed. This is quite unusual since such large enhancement of S at comparable p has only been reported in several cases such as the existence of resonant states,^{18, 54} band convergence/ overlapping,^55-58 or electron critical scattering.⁵⁹ Here, we attribute the enhanced S to the disorder-induced electronic localization,^{52, 60} which qualitatively alters the nature of the wavefunction and the conduction mechanism. For amorphous materials or complex crystalline systems with large disorder, the Seebeck coefficient is intimately related to the enthalpy barrier of carrier hopping between neighbor localized states.^{52, 61} With increasing S content, the disorder strength is gradually increased, resulting in larger enthalpy barriers and thus higher Seebeck coefficients.

The TE properties of Cu₂Te_1-xI_x and Cu₂Te_0.9-yI_0.1S_y as a function of temperature are plotted in Figure 5. Both electrical resistivity (ρ) and Seebeck coefficient (S) are significantly increased with an increasing amount of I and S content. The ρ for pristine Cu₂Te is on the order of 10^-6 Ω m, which is enhanced by nearly two orders of magnitude, reaching (1-3) × 10^-4 Ω m in Cu₂Te_0.4I_0.1S_0.5. With increasing values of ρ, the temperature coefficient of resistivity (TCR) gradually turns from positive in Cu₂Te to negative in Cu₂Te_0.4I_0.1S_0.5 (Figure 5a and Figure S3c). The change of sign of TCR is reminiscent of the Mooij correlation,⁶² which is typically related with the incipient Anderson localization in highly disordered metals.⁶³ Furthermore, the low temperature electrical resistivities of Cu₂Te_0.5I_0.1S_0.4 and Cu₂Te_0.4I_0.1S_0.5 follow the relation lnρ vs. T^-1/4 (Figure S4),⁵² which is also a signature of variable-range hopping conduction for disordered systems. The maximum S for pristine Cu₂Te is only 74 mV K^-1, which is improved to 102 mV K^-1 for Cu₂Te_0.9I_0.1, and further enhanced to 260 mV K^-1 for Cu₂Te_0.4I_0.1S_0.5 (Figure 5a). Note this value is the highest Seebeck coefficient reported in Cu₂Te-based materials. The positive sign of Seebeck coefficients and the positive sign of Hall coefficients indicate that holes are the majority charge carrier. The power factor (PF) is slightly improved when the S alloying content y is lower than 0.3; however, with further increasing y, the PF is gradually decreased. Specifically, a maximum PF of 8.7 μW cm^-1 K^-2 is obtained for Cu₂Te_0.6I_0.1S_0.3 at 850 K.

Figure 5d displays the total thermal conductivity (κ) as a function of temperature for Cu₂Te_1-xI_x and Cu₂Te_0.9-yI_0.1S_y. Most samples exhibit complex temperature dependencies of κ from 300 to 850 K due to the existence of multiple structural transformations.^{23, 24} Notably, κ is significantly reduced with increasing I and S content, which largely stems from the decreased electronic contribution to thermal transport. The lowest κ of 0.3 W m^-1 K^-1 is achieved in Cu₂Te_0.5I_0.1S_0.4, which is only one ninth of that of Cu₂Te. The lattice thermal conductivity (κ_L) for Cu₂Te_1-x-yI_xS_y is only 0.27 W m^-1 K^-1 at both low and high temperatures (cf. Figure S5), approaching the amorphous limit. The low κ_L is attributed to the strong phonon scattering by the as formed hierarchical structural modularity and/or the emerging quasi-particles such as propagons, diffusons, and locons instead of the phonons in the strict sense.⁶⁴

Benefiting from the improved PF and reduced κ, the TE figures of merit zT are greatly enhanced over the entire temperature range studied (cf. Figure 5e). Specifically, a record-high zT of ~1.4 at 850 K is achieved in Cu₂Te_0.5I_0.1S_0.4, an improvement of ~ 370% over that of the pristine Cu₂Te (zT = 0.29). This zT value is not only much higher than the literature data of Cu₂Te-based TE materials (cf. Figure 5f) but also attained near the MIR limit in contrast to most other state-of-the-art TE materials that are band conductors (cf. Figure 1b).

In summary, we devise an effective method to integrate the structural-functional modules in the liquid-like TE material Cu₂Te. The aliovalent I dopants in the Te-sites not only stabilize hexagonal structure at room temperature but also act as donors to substantially reduce the hole concentration otherwise too high. Meanwhile, the introduction of isovalent S dopants induces sublattice-level distortions and Anderson localization, which enables a great enhancement of Seebeck coefficient and an ultralow lattice thermal conductivity. Near the Mott-Ioffe-Regel limit where the carrier mobility is exceptionally low, a state-of-the-art zT of 1.4 is achieved at 850 K in Cu₂Te_0.5I_0.1S_0.4, in contrast to the state-of-the-art TE thermoelectric materials that are well-established band conductors. The doping induced hierarchical structural modularity and the discovery of high zT values near the MIR limit in copper tellurides thus present a case of paradigm shift from the band edge to the mobility edge in TE materials research.

Synthesis. Polycrystalline Cu₂Te₁_-x-yI_xS_y samples were synthesized by a melting-annealing method followed by spark plasma sintering. High-purity raw materials of Cu (Sigma Aldrich, 99.999%), Te (Sigma Aldrich, 99.999%), CuI (Sigma Aldrich, 99.9%), and S (Sigma Aldrich, 99.999%) were weighed according to the nominal compositions of Cu₂Te_1-xI_x (x = 0.05, 0.1, 0.12, and 0.15) and Cu₂Te_0.9-yI_0.1S_y (y = 0.1, 0.2, 0.3, 0.4, and 0.5) and then put inside a pyrolytic boron nitride crucible that sealed in evacuated quartz tubes. The loaded tubes were flame-sealed and then heated to 1403 K in 12 h, soaked at this temperature for 12 h, cooled to 923 K in 50 h, annealed at 923 K for 4 days, and subsequently cooled to room temperature by turning off the furnace power. After removing the copper precipitate on the surface, the obtained ingots were hand-ground into fine powders and then densified using a spark plasma sintering (Sumitomo SPS-2040) apparatus at 773-823 K under a pressure of 60-65 MPa. Boron nitride was sprayed on the carbon foils and the inner walls of the graphite die to prevent currents from going through the samples causing undesired ionic migration. Finally, highly dense (>97% of theoretical density) disk-shaped pellets were obtained.

Characterization. Room-temperature powder XRD characterization was performed using Rigaku Rint 2000 diffractometer equipped with a Cu-K_α source. Rietveld refinement was performed to calculate the lattice parameters using FULLPROF software. The sample compositions were estimated using energy dispersive X-ray analysis (EDS, Horiba 250) that equipped in field emission scanning electron microscopy (FESEM, Magellan-400). Atom-probe tomography (APT) analysis was performed in a Cameca Instruments (LEAP 5000 XR) by applying a DC voltage of 2-4 kV and laser pulse energy of 3 pJ. 20 million ions were collected by the APT with a 50 K measurement temperature and a detection rate of 1%. The needled-sharped samples for the APT analysis were prepared using the standard lift-out procedure by a focused ion beam lift-off methodology (Helios, Nanolab 600). Aberration-corrected scanning transmission electron microscopy (STEM) investigation was conducted on a probe-corrected Hitachi® HF5000 operating at 200kV. The electrical conductivity (σ) and Seebeck coefficient (S) were simultaneously measured by the ULVAC ZEM-3 apparatus. The thermal diffusivity (D) was measured via the laser flash technique with a Netzsch LFA-457. The specific heat (C_p) was estimated by using the Dulong-Petit law. The pellet density (d) was measured by the Archimedes method. The total thermal conductivity (κ) was calculated from the equation κ = d ´ C_p ´ D. The Hall coefficient (R_H) was measured using PPMS-9 with magnetic field swept from -3 to 3 T. The Hall carrier concentration (p) and mobility (μ) were calculated by p = 1/eR_H and μ = σR_H, respectively.

Defect formation energy calculations: The calculations were performed within the framework of density functional theory (DFT) with projector-augmented wave (PAW) method, as implemented in the Vienna Ab Initio Simulation Package (VASP).⁶⁵ The cutoff energy of the plane wave was set at 500 eV. The energy convergence criterion was chosen to be 1 × 10^-5 eV per unit cell. A 2×2×2 Cu₂Te supercell containing 48 atoms was used in all DFT calculations. The Brillouin zone integration was sampled using Monkhorst-Pack grids⁶⁶ with a 9×9×9 k-point mesh. The E_v of a Cu vacancy (V_Cu) is calculated according to the equation

Conflicts of interest

There are no conflicts to declare.

Acknowledgements

This work was supported by the National Key Research and Development Program of China (2018YFB0703600), National Natural Science Foundation of China (No. 91963208, 51625205, 91963208, 52072388, and 51961135106), and Shanghai Government (20JC1415100). K.Z. thanks the support by the National Natural Science Foundation of China (51902199) and Shanghai Sailing Program under Grant No. 19YF1422800.

1. He, J.; Tritt, T. M., Advances in thermoelectric materials research: Looking back and moving forward. Science 2017, 357 (6358).

2. Shi, X. L.; Zou, J.; Chen, Z. G., Advanced Thermoelectric Design: From Materials and Structures to Devices. Chem Rev 2020.

3. Zhao, K.; Qiu, P.; Shi, X.; Chen, L., Recent Advances in Liquid‐Like Thermoelectric Materials. Advanced Functional Materials 2019, 30 (8).

4. Zhu, T.; Liu, Y.; Fu, C.; Heremans, J. P.; Snyder, J. G.; Zhao, X., Compromise and Synergy in High-Efficiency Thermoelectric Materials. Adv Mater 2017, 29 (14).

5. Tan, G.; Zhao, L. D.; Kanatzidis, M. G., Rationally Designing High-Performance Bulk Thermoelectric Materials. Chem Rev 2016.

6. Ren, G.-K.; Lan, J.-L.; Zhao, L.-D.; Liu, C.; Yuan, H.; Shi, Y.; Zhou, Z.; Lin, Y.-H., Layered oxygen-containing thermoelectric materials: Mechanisms, strategies, and beyond. Materials Today 2019, 29, 68-85.

7. Koumoto, K.; Terasaki, I.; Funahashi, R., Complex oxide materials for potential thermoelectric applications. MRS bulletin 2006, 31 (3), 206-210.

8. Zhao, K.; Eikeland, E.; He, D.; Qiu, W.; Jin, Z.; Song, Q.; Wei, T.-r.; Qiu, P.; Liu, J.; He, J.; Iversen, B. B.; He, J.; Chen, L.; Shi, X., Thermoelectric materials with crystal-amorphicity duality induced by large atomic size mismatch. Joule 2021.

9. Shikano, M.; Funahashi, R., Electrical and thermal properties of single-crystalline (Ca 2 CoO 3) 0.7 CoO 2 with a Ca 3 Co 4 O 9 structure. Applied Physics Letters 2003, 82 (12), 1851-1853.

10. Shi, X.; Yang, J.; Salvador, J. R.; Chi, M.; Cho, J. Y.; Wang, H.; Bai, S.; Yang, J.; Zhang, W.; Chen, L., Multiple-Filled Skutterudites: High Thermoelectric Figure of Merit through Separately Optimizing Electrical and Thermal Transports. Journal of the American Chemical Society 2011, 133 (20), 7837-7846.

11. Liu, H.; Shi, X.; Xu, F.; Zhang, L.; Zhang, W.; Chen, L.; Li, Q.; Uher, C.; Day, T.; Snyder, G. J., Copper ion liquid-like thermoelectrics. Nature Materials 2012, 11 (5), 422-425.

12. Hu, L.; Zhu, T.; Liu, X.; Zhao, X., Point defect engineering of high‐performance bismuth‐telluride‐based thermoelectric materials. Advanced Functional Materials 2014, 24 (33), 5211-5218.

13. Zhang, Z.; Zhao, K.; Wei, T.-R.; Qiu, P.; Chen, L.; Shi, X., Cu2Se-Based liquid-like thermoelectric materials: looking back and stepping forward. Energy & Environmental Science 2020, 13 (10), 3307-3329.

14. Jin, Z.; Xiong, Y.; Zhao, K.; Dong, H.; Ren, Q.; Huang, H.; Qiu, X.; Xiao, J.; Qiu, P.; Chen, L.; Shi, X., Abnormal thermal conduction in argyrodite-type Ag9FeS6-Te materials. Materials Today Physics 2021, 19.

15. Wu, Y.; Chen, Z.; Nan, P.; Xiong, F.; Lin, S.; Zhang, X.; Chen, Y.; Chen, L.; Ge, B.; Pei, Y., Lattice Strain Advances Thermoelectrics. Joule 2019, 3 (5), 1276-1288.

16. Meng, X.; Liu, Z.; Cui, B.; Qin, D.; Geng, H.; Cai, W.; Fu, L.; He, J.; Ren, Z.; Sui, J., Grain Boundary Engineering for Achieving High Thermoelectric Performance in n-Type Skutterudites. Advanced Energy Materials 2017, 1602582.

17. Kim, S. I.; Lee, K. H.; Mun, H. A.; Kim, H. S.; Hwang, S. W.; Roh, J. W.; Yang, D. J.; Shin, W. H.; Li, X. S.; Lee, Y. H., Dense dislocation arrays embedded in grain boundaries for high-performance bulk thermoelectrics. Science 2015, 348 (6230), 109-114.

18. Heremans, J. P.; Wiendlocha, B.; Chamoire, A. M., Resonant levels in bulk thermoelectric semiconductors. Energy Environ. Sci. 2012, 5 (2), 5510-5530.

19. Gayner, C.; Amouyal, Y., Energy Filtering of Charge Carriers: Current Trends, Challenges, and Prospects for Thermoelectric Materials. Advanced Functional Materials 2019, 30 (18).

20. Zhao, K.; Blichfeld, A. B.; Chen, H.; Song, Q.; Zhang, T.; Zhu, C.; Ren, D.; Hanus, R.; Qiu, P.; Iversen, B. B.; Xu, F.; Snyder, G. J.; Shi, X.; Chen, L., Enhanced Thermoelectric Performance through Tuning Bonding Energy in Cu2Se1–xSx Liquid-like Materials. Chemistry of Materials 2017, 29 (15), 6367-6377.

21. Hong, M.; Wang, Y.; Feng, T.; Sun, Q.; Xu, S.; Matsumura, S.; Pantelides, S. T.; Zou, J.; Chen, Z.-G., Strong Phonon–Phonon Interactions Securing Extraordinary Thermoelectric Ge1–x Sb x Te with Zn-Alloying-Induced Band Alignment. Journal of the American Chemical Society 2018, 141 (4), 1742-1748.

22. Snyder, G. J.; Snyder, A. H.; Wood, M.; Gurunathan, R.; Snyder, B. H.; Niu, C., Weighted mobility. Advanced Materials 2020, 32 (25), 2001537.

23. Asadov, Y. G.; Rustamova, L. V.; Gasimov, G. B.; Jafarov, K. M.; Babajev, A. G., Structural phase transitions in Cu2–xTe crystals (x= 0.00, 0.10, 0.15, 0.20, 0.25). Phase Transitions 1992, 38 (4), 247-259.

24. He, Y.; Zhang, T.; Shi, X.; Wei, S.-H.; Chen, L., High thermoelectric performance in copper telluride. NPG Asia Materials 2015, 7 (8), e210.

25. Zhao, K.; Liu, K.; Yue, Z.; Wang, Y.; Song, Q.; Li, J.; Guan, M.; Xu, Q.; Qiu, P.; Zhu, H.; Chen, L.; Shi, X., Are Cu2 Te-Based Compounds Excellent Thermoelectric Materials? Adv Mater 2019, 31 (49), e1903480.

26. Mallick, M. M.; Vitta, S., Realizing high figure-of-merit in Cu2Te using a combination of doping, hierarchical structure, and simple processing. Journal of Applied Physics 2017, 122 (2), 024903.

27. Hussey‖, N.; Takenaka, K.; Takagi, H., Universality of the Mott–Ioffe–Regel limit in metals. Philosophical Magazine 2004, 84 (27), 2847-2864.

28. Gunnarsson, O.; Calandra, M.; Han, J., Colloquium: Saturation of electrical resistivity. Reviews of Modern Physics 2003, 75 (4), 1085.

29. He, Y.; Lu, P.; Shi, X.; Xu, F.; Zhang, T.; Snyder, G. J.; Uher, C.; Chen, L., Ultrahigh Thermoelectric Performance in Mosaic Crystals. Adv Mater 2015, 27 (24), 3639-44.

30. Ballikaya, S.; Chi, H.; Salvador, J. R.; Uher, C., Thermoelectric properties of Ag-doped Cu2Se and Cu2Te. Journal of Materials Chemistry A 2013, 1 (40), 12478.

31. Qiu, Y.; Liu, Y.; Ye, J.; Li, J.; Lian, L., Synergistic optimization of carrier transport and thermal conductivity in Sn-doped Cu2Te. Journal of Materials Chemistry A 2018, 6 (39), 18928-18937.

32. Mukherjee, S.; Parasuraman, R.; Umarji, A. M.; Rogl, G.; Rogl, P.; Chattopadhyay, K., Effect of Fe alloying on the thermoelectric performance of Cu2Te. Journal of Alloys and Compounds 2020, 817, 152729.

33. Sarkar, S.; Sarswat, P. K.; Saini, S.; Mele, P.; Free, M. L., Synergistic effect of band convergence and carrier transport on enhancing the thermoelectric performance of Ga doped Cu 2 Te at medium temperatures. Scientific reports 2019, 9 (1), 1-15.

34. Wood, C.; Emin, D., Refractory materials for high-temperature thermoelectric energy conversion. MRS Online Proceedings Library (OPL) 1983, 24.

35. Jood, P.; Ohta, M.; Yamamoto, A.; Kanatzidis, M. G., Excessively Doped PbTe with Ge-Induced Nanostructures Enables High-Efficiency Thermoelectric Modules. Joule 2018, 2 (7), 1339-1355.

36. Joshi, G.; Lee, H.; Lan, Y.; Wang, X.; Zhu, G.; Wang, D.; Gould, R. W.; Cuff, D. C.; Tang, M. Y.; Dresselhaus, M. S., Enhanced thermoelectric figure-of-merit in nanostructured p-type silicon germanium bulk alloys. Nano letters 2008, 8 (12), 4670-4674.

37. Hao, F.; Qiu, P.; Tang, Y.; Bai, S.; Xing, T.; Chu, H.-S.; Zhang, Q.; Lu, P.; Zhang, T.; Ren, D.; Chen, J.; Shi, X.; Chen, L., High efficiency Bi2Te3-based materials and devices for thermoelectric power generation between 100 and 300 °C. Energy Environ. Sci. 2016, 9 (10), 3120-3127.

38. He, Y.; Day, T.; Zhang, T.; Liu, H.; Shi, X.; Chen, L.; Snyder, G. J., High Thermoelectric Performance in Non-Toxic Earth-Abundant Copper Sulfide. Advanced Materials 2014, 26 (23), 3974-3978.

39. Heep, B. K.; Weldert, K. S.; Krysiak, Y.; Day, T. W.; Zeier, W. G.; Kolb, U.; Snyder, G. J.; Tremel, W., High Electron Mobility and Disorder Induced by Silver Ion Migration Lead to Good Thermoelectric Performance in the Argyrodite Ag8SiSe6. Chemistry of Materials 2017, 29 (11), 4833-4839.

40. Jood, P.; Chetty, R.; Ohta, M., Structural stability enables high thermoelectric performance in room temperature Ag 2 Se. Journal of Materials Chemistry A 2020, 8 (26), 13024-13037.

41. Xing, T.; Song, Q.; Qiu, P.; Zhang, Q.; Xia, X.; Liao, J.; Liu, R.; Huang, H.; Yang, J.; Bai, S.; Ren, D.; Shi, X.; Chen, L., Superior performance and high service stability for GeTe-based thermoelectric compounds. National Science Review 2019, 6 (5), 944-954.

42. Zhang, J.; Song, L.; Pedersen, S. H.; Yin, H.; Hung, L. T.; Iversen, B. B., Discovery of high-performance low-cost n-type Mg3Sb2-based thermoelectric materials with multi-valley conduction bands. Nat Commun 2017, 8, 13901.

43. Wei, T. R.; Tan, G.; Zhang, X.; Wu, C. F.; Li, J. F.; Dravid, V. P.; Snyder, G. J.; Kanatzidis, M. G., Distinct Impact of Alkali-Ion Doping on Electrical Transport Properties of Thermoelectric p-Type Polycrystalline SnSe. J Am Chem Soc 2016, 138 (28), 8875-82.

44. Tan, Q.; Zhao, L.-D.; Li, J.-F.; Wu, C.-F.; Wei, T.-R.; Xing, Z.-B.; Kanatzidis, M. G., Thermoelectrics with earth abundant elements: low thermal conductivity and high thermopower in doped SnS. Journal of Materials Chemistry A 2014, 2 (41), 17302-17306.

45. Kunpeng Zhao, F. X., Xun Shi, Jian He, and Lidong Chen, Novel meta-phase beyond classic Hume-Rothery rules. submitted 2021.

46. Zhao, K.; Zhu, C.; Qiu, P.; Blichfeld, A. B.; Eikeland, E.; Ren, D.; Iversen, B. B.; Xu, F.; Shi, X.; Chen, L., High thermoelectric performance and low thermal conductivity in Cu₂₋_yS_1/3Se_1/3Te_1/3 liquid-like materials with nanoscale mosaic structures. Nano Energy 2017, 42, 43-50.

47. Yao, Y.; Zhang, B. P.; Pei, J.; Sun, Q.; Nie, G.; Zhang, W. Z.; Zhuo, Z. T.; Zhou, W., High Thermoelectric Figure of Merit Achieved in Cu2S1- xTe x Alloys Synthesized by Mechanical Alloying and Spark Plasma Sintering. ACS applied materials & interfaces 2018, 10 (38), 32201-32211.

48. Zhu, T.; Hu, L.; Zhao, X.; He, J., New insights into intrinsic point defects in V2VI3 thermoelectric materials. Advanced Science 2016, 3 (7), 1600004.

49. Roychowdhury, S.; Ghosh, T.; Arora, R.; Samanta, M.; Xie, L.; Singh, N. K.; Soni, A.; He, J.; Waghmare, U. V.; Biswas, K., Enhanced atomic ordering leads to high thermoelectric performance in AgSbTe2. Science 2021, 371 (6530), 722-727.

50. Anderson, P. W., Absence of diffusion in certain random lattices. Physical review 1958, 109 (5), 1492.

51. Abrahams, E.; Anderson, P.; Licciardello, D.; Ramakrishnan, T., Scaling theory of localization: Absence of quantum diffusion in two dimensions. Physical Review Letters 1979, 42 (10), 673.

52. Mott, N. F.; Davis, E. A., Electronic processes in non-crystalline materials. OUP Oxford: 2012.

53. Yamamoto, K.; Aharony, A.; Entin-Wohlman, O.; Hatano, N., Thermoelectricity near Anderson localization transitions. Physical Review B 2017, 96 (15), 155201.

54. Hong, M.; Chen, Z. G.; Yang, L.; Zou, Y. C.; Dargusch, M. S.; Wang, H.; Zou, J., Realizing zT of 2.3 in Ge1-x-y Sbx Iny Te via Reducing the Phase-Transition Temperature and Introducing Resonant Energy Doping. Adv Mater 2018, 30 (11).

55. Pei, Y.; Shi, X.; LaLonde, A.; Wang, H.; Chen, L.; Snyder, G. J., Convergence of electronic bands for high performance bulk thermoelectrics. Nature 2011, 473 (7345), 66-9.

56. Liu, W.; Tan, X.; Yin, K.; Liu, H.; Tang, X.; Shi, J.; Zhang, Q.; Uher, C., Convergence of conduction bands as a means of enhancing thermoelectric performance of n-type Mg2Si(1-x)Sn(x) solid solutions. Phys Rev Lett 2012, 108 (16), 166601.

57. Goldsmid, H. J., Introduction to thermoelectricity. Springer: 2010; Vol. 121.

58. Zhang, J.; Liu, R.; Cheng, N.; Zhang, Y.; Yang, J.; Uher, C.; Shi, X.; Chen, L.; Zhang, W., High-performance pseudocubic thermoelectric materials from non-cubic chalcopyrite compounds. Adv Mater 2014, 26 (23), 3848-53.

59. Liu, H.; Yuan, X.; Lu, P.; Shi, X.; Xu, F.; He, Y.; Tang, Y.; Bai, S.; Zhang, W.; Chen, L.; Lin, Y.; Shi, L.; Lin, H.; Gao, X.; Zhang, X.; Chi, H.; Uher, C., Ultrahigh Thermoelectric Performance by Electron and Phonon Critical Scattering in Cu2Se1-xIx. Advanced Materials 2013, 25 (45), 6607-6612.

60. Enderby, J.; Barnes, A., Electron transport at the Anderson transition. Physical Review B 1994, 49 (7), 5062.

61. Würger, A., Thermoelectric ratchet effect for charge carriers with hopping dynamics. Physical Review Letters 2021, 126 (6), 068001.

62. Mooij, J., Electrical conduction in concentrated disordered transition metal alloys. physica status solidi (a) 1973, 17 (2), 521-530.

63. Imry, Y., Possible role of incipient Anderson localization in the resistivities of highly disordered metals. Physical Review Letters 1980, 44 (7), 469.

64. Qian, X.; Zhou, J.; Chen, G., Phonon-engineered extreme thermal conductivity materials. Nature Materials 2021, 1-15.

65. Kresse, G.; Furthmüller, J., Efficient iterative schemes for ab initio total-energy calculations using a plane-wave basis set. Physical review B 1996, 54 (16), 11169.

66. Monkhorst, H. J.; Pack, J. D., Special points for Brillouin-zone integrations. Physical review B 1976, 13 (12), 5188.

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Structural Modularization of Cu₂Te Leading to High Thermoelectric Performance near the Mott-Ioffe-Regel Limit

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