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Cu3SbSe4, consisting of earth-abundant and inexpensive elements, is a promising p-type thermoelectric (TE) material. However, its thermoelectric performance is low in comparison with typical Pb-based materials. Here, we tune Ag content to optimize synergistically electrical and thermal transport properties for achieving high TE performance of Bi-doped Cu3SbSe4 materials. Dual-incorporation of Bi and Ag spontaneously generates multiple secondary phases involving CuSe and AgSbSe2. The multiscale defects including point defects, dislocations, nanoprecipitates and grain boundaries can enhance phonon scattering, thereby obtaining a low thermal conductivity (κ) of ~ 0.67 W m−1 K−1 at 673 K. The carrier concentration is improved due to the enhanced Cu vacancies caused by softening of Cu 3d–Se 4p bond after Ag doping, leading to the obviously increased electrical conductivity (σ). Meanwhile, the heavy element dopants (Bi and Ag) can modify the band structure to enhance Seebeck coefficient (S) by enlarging band gap (Eg) and increasing carrier effective mass (m*). The simultaneously enhanced σ and S result in a large power factor (S2σ) of ~1200 μW m−1 K−2 at 673 K. Consequently, a maximum ZT of ~1.18 (~136% higher than that of pristine Cu3SbSe4) at 673 K and an averaged ZT of ~ 0.51 at 300–673 K are achieved for Cu2.85Ag0.15Sb0.985Bi0.015Se4 sample due to a low κ and a high S2σ. This work offers a referential strategy to improve the comprehensive TE performance by dual-incorporation with isovalent heavy element doping for the diamond-like materials.

Cu3SbSe4-Based materials were fabricated through Sn-doping and AgSb0.98Ge0.02Se2 incorporation and their thermoelectric properties were investigated in the temperature range from 300 K to 675 K. A remarkable enhancement in thermoelectric performance was obtained, which can be ascribed to the synergistic adjustment of electrical and thermal transport. The introduction of AgSb0.98Ge0.02Se2 nanoparticles strengthened phonon scattering in the composites, resulting in a low thermal conductivity. Simultaneously, a high power factor was maintained. As a result, a maximum figure of merit of 1.23 was obtained at 675 K for the sample Cu3Sb0.96Sn0.04Se4–3 wt% AgSb0.98Ge0.02Se2, which is one of the highest values ever reported in the Cu3SbSe4-based system.

How to further improve the thermoelectric performance in Cu3SbSe4-based materials after optimizing its carrier concentration is a difficult issue. The present study attempts to address the issue by...

Large-scale Sn and/or S doped Cu3Sb1−xSnxSe4−ySy (x = 0.02, 0.04, 0.06 and 0.10; y = 0, 0.5) nanoparticles were first prepared through a low-temperature co-precipitation route. The effects of Sn doping on the thermoelectric properties of the Cu3SbSe4-based materials were explored. Due to the improved power factor from optimizing the carrier concentration and the reduced lattice thermal conductivity from enhanced phonon scattering at the grain interfaces, the maximum thermoelectric figure of merit, ZTmax, obtained here reached 1.1 for the co-doped Cu3Sb0.94Sn0.06Se3.5S0.5 material, which is the largest value reported for Cu3SbSe4-based materials.

Cu3SbSe4-based materials have attracted much attention for thermoelectric power generation in the mid-temperature range due to their low cost, ecofriendliness, and abundant elements on the earth. However, the peak figure of merit (ZT) for the Cu3SbSe4-based system prepared by the fusion method is usually smaller than unity because of its high thermal conductivity. Here, we show that through a coprecipitation method combined with spark plasma sintering ultrafine-grained Cu3Sb0.94Sn0.06Se4–ySy (y = 0, 0.5) embedded with Cu3SbSe3 nanoprecipitates can be prepared. Due to the ultralow thermal conductivity and enhanced Seebeck coefficient, a record-high ZT value of 1.32 is achieved for the sample Cu3Sb0.94Sn0.06Se3.5Se0.5. The ultralow thermal conductivity is attributed to the enhanced phonon scattering caused by the nanoprecipitates and fine grains of the samples, and the improved Seebeck coefficient originates from the enhancement of electronic density-of-state effective mass. Present results demonstrate that...

We report the realization of high thermoelectric performance in Cu3SbSe4-based materials through Sn-doping and inclusion of Cu3Sb0.94Sn0.06Se2.5S1.5 nanostructure. This significant enhancement in thermoelectric performance is attributed to simultaneous modulation of the electrical and thermal transport. Sn doping can reduce electrical resistivity, maintaining its high power factor. Cu3Sb0.94Sn0.06Se2.5S1.5 nanoparticles dispersed in the matrix can strengthen interface scattering at the phase boundaries, which can effectively scatter the heat-carrying phonons and thus yielding low lattice thermal conductivity. As a result, the figure of merit reaches ∼0.87 at 673 K for Cu3Sb0.96Sn0.04Se4–3% Cu3Sb0.94Sn0.06Se2.5S1.5.

Cu3SbSe4, featuring its earth-abundant, cheap, nontoxic and environmentally-friendly constituent elements, can be considered as a promising intermediate temperature thermoelectric (TE) material. Herein, a series of p-type Bi-doped Cu3Sb1 − xBixSe4 (x = 0-0.04) samples were fabricated through melting and hot pressing (HP) process, and the effects of isovalent Bi-doping on their TE properties were comparatively investigated by experimental and computational methods. TEM analysis indicates that Bi-doped samples consist of Cu3SbSe4 and Cu2 − xSe impurity phases, which is in good agreement with the results of XRD, SEM and XPS. For Bi-doped samples, the reduced electrical resistivity (ρ) caused by the optimized carrier concentrations and enhanced Seebeck coefficient derived from the densities of states near the Fermi level give rise to a high power factor of ~ 1000 µWcm− 1K− 2 at 673 K for the Cu3Sb0.985Bi0.015Se4 sample. Additionally, the multiscale defects of Cu3SbSe4-based materials involving point defects, nanoprecipitates, amorphous phases and grain boundaries can strongly scatter phonons to depress lattice thermal conductivity (κlat), resulting in a low κlat of ~ 0.53 Wm− 1K− 1 and thermal conductivity (κtot) of ~ 0.62 Wm− 1K− 1 at 673 K for the Cu3Sb0.98Bi0.02Se4 sample. As a consequence, a maximum ZT value ~ 0.95 at 673 K is obtained for the Cu3Sb0.985Bi0.015Se4 sample, which is ~ 1.9 times more than that of pristine Cu3SbSe4. This work shows that isovalent heavy-element doping is an effective strategy to optimize thermoelectric properties of copper-based chalcogenides.

In this study, we develop a synergistic modulation of the thermal conductivity and power factor of Cu3SbSe4-based materials through Sn and Zr or Hf co-doping by using a facile microwave-assisted solvothermal method. A series of Cu3Sb1-xMxSe4 (M = Zr or Hf, x = 0, 0.02, 0.04, 0.06 and 0.08) compounds are firstly synthesized through the microwave-assisted solvothermal method combined with spark plasma sintering (SPS) process. The effect of Zr and Hf doping on the thermoelectric properties of Cu3Sb1-xMxSe4 (M = Zr or Hf) has been investigated. With increasing the content of Hf and Zr, the thermal conductivity of Cu3Sb1-xMxSe4 (M = Zr or Hf) is obviously decreased to 0.518 Wm−1K−1 of Cu3Sb0.92Hf0.08Se4 and 0.433 Wm−1K−1 of Cu3Sb0.92Zr0.08Se4 at 623 K, respectively. In addition, Sn doping further improves the low electrical conductivity and boosts the power factor, yielding a peak zT value of ~0.82 of Cu3Sb0.91Sn0.03Hf0.06Se4 at 623 K, which is ~228% higher than that of the pristine Cu3SbSe4. Our work provides a new methodology for the decoupling of thermal and electrical properties of the Cu3SbSe4-based thermoelectric materials.

(Ag,Sn) co-doped Cu3SbSe4 nanocrystals are obtained via a facile microwave-assisted solvothermal method, and their thermoelectric properties are investigated in the temperature range from 300 K to 623 K. Sn-doping on Sb sites dramatically increases the carrier concentration and thus the electrical conductivity, promoting the thermoelectric power factor. Further alloying with Ag on Cu sites strongly suppresses the lattice thermal conductivity close to the glass limit. Aside from point defect scattering, such reduction in lattice thermal conductivity largely relies on the formation of Cu2-xSe nanoinclusions, which serve as additional scattering centers for phonons. Overall, the sample with the nominal composition of Cu2.8Ag0.2Sb0.95Sn0.05Se4 reaches a minimum lattice thermal conductivity of 0.27 W m-1 K-1 and a maximum zT of 1.18 at 623 K, which is the best result for the Cu3SbSe4-based materials in the same temperature region. Our results demonstrate that the microwave-assisted synthesis method is capable of fabricating Cu based ternary compounds with high thermoelectric performance.