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The chalcopyrite compound CuGa(In)Te2 has garnered significant attention due to its safe elemental composition and high thermoelectric potential. Optimizing the carrier concentration and reducing the lattice thermal conductivity of CuGa(In)Te2 can significantly enhance its thermoelectric performance. In this mini-review, we analyze the electronic and phonon structures of CuGa(In)Te2, summarize and categorize the representative methods employed in recent years to improve its thermoelectric performance. Our analysis reveals that reducing thermal conductivity has a more significant impact on enhancing the ZT value of CuGa(In)Te2 compared to increasing the power factor. In conclusion, we outline potential challenges and provide a brief outlook, offering valuable insights into the design of CuGa(In)Te2 chalcopyrite compounds as high-performance thermoelectric materials. [ABSTRACT FROM AUTHOR]

As a derivative of GeTe and MnTe, GeMnTe2 exhibits a cubic structure with no phase transition. Compared to GeTe, it is considerably cheaper and has a significantly high carrier concentration compared to MnTe, making it an excellent thermoelectric (TE) material with promising applications. Herein, a charge‐balanced vacancy engineering strategy is employed, resulting in a significant improvement in the power factor of GeMnTe2. Furthermore, the density functional theory calculation shows that the doping of Bi and the absence of Ge synergically increase the density of states near the Fermi level. Power factors of ≈13.7 μW cm−1 K−2 are achieved at 8% Bi content, a 22% improvement compared to the undoped system, while a final maximum ZT value of about 1.12 and an average ZT value of 0.72 are achieved. This indicates that charge‐balance vacancy engineering is an effective optimization method for the GeMnTe2 system, which can effectively improve the TE performance. [ABSTRACT FROM AUTHOR]

Here, a typical microwave hydrothermal-assisted synthesis method is utilized to fabricate Co/Sn co-doped Cu 3 SbSe 4 materials. Experimental results demonstrate that the formation of a nanoscale Co 9 Se 8 phase occurs when the solid solubility of Co is exceeded. This phase effectively enhances phonon scattering at the grain boundary's high-density dislocation region, leading to a significant reduction in lattice thermal conductivity. Simultaneously, the interface between Co 9 Se 8 and Cu 3 SbSe 4 exhibits an energy filtering effect, resulting in an improved Seebeck coefficient. The maximum zT value of 0.62 is achieved in the Cu 3 Sb 0.96 Co 0.04 Se 4 sample. To further regulate the carrier concentration, Sn atoms are introduced, leading to peak power factor and zT values of 865.98 μW·m−1·K−2 and 0.72, respectively. The incorporation of Co and Sn doping contributes to the enhancement of mechanical properties by reinforcing covalent bonds. Mechanical property testing of the materials indicates an improvement in mechanical performance upon doping with Co and Sn. This study provides valuable insights into the in-situ introduction of a second phase through element doping, thereby enhancing the comprehensive thermoelectric properties of Cu 3 SbSe 4 -based materials. Moreover, it establishes an experimental foundation for subsequent investigations into the materials' mechanical properties. • Co 9 Se 8 phase effectively enhances phonon scattering at the grain boundary region. • The energy filtering effect results in an improved Seebeck coefficient. • Sn doping was further performed to optimize the carrier concentration. • The mechanical properties enhanced by the strengthen of the covalent bonds. • The zT max of the Co/Sn co-doped sample was 0.72 at 673 K. [ABSTRACT FROM AUTHOR]

As a derivative of GeTe and MnTe, GeMnTe2 exhibits a cubic structure with no phase transition. Compared to GeTe, it is considerably cheaper and has a significantly high carrier concentration compared to MnTe, making it an excellent thermoelectric (TE) material with promising applications. Herein, a charge‐balanced vacancy engineering strategy is employed, resulting in a significant improvement in the power factor of GeMnTe2. Furthermore, the density functional theory calculation shows that the doping of Bi and the absence of Ge synergically increase the density of states near the Fermi level. Power factors of ≈13.7 μW cm−1 K−2 are achieved at 8% Bi content, a 22% improvement compared to the undoped system, while a final maximum ZT value of about 1.12 and an average ZT value of 0.72 are achieved. This indicates that charge‐balance vacancy engineering is an effective optimization method for the GeMnTe2 system, which can effectively improve the TE performance. [ABSTRACT FROM AUTHOR]

[Display omitted] • A high ZT of > 1.5 is achieved at 703 K in Sc/Te co-doped Mg 3.2 Sb 1.5 Bi 0.5. • Both Sc Mg and Te Bi point effects improve the overall thermoelectric performance. • First-principles DFT calculations are introduced to guide the overall material design. • Single parabolic band model confirms the optimized carrier density and ZT. Mg 3+ δ X 2 (X = Sb, Bi) based Zintl phases possess characteristics, such as non-toxicity, cost-effectiveness, ease of fabrication, and a wide range of working temperatures, showing high thermoelectric potential as a n-type thermoelectric material. However, there exists a relative research gap in understanding the underlying mechanisms behind improving their thermoelectric performance through doping, and the corresponding influence on the micro/nanostructures of the materials. Here, guided by the first-principles calculations, we design Mg 3.2 Sb 1.5 Bi 0.5 -based thermoelectric Zintl phases co-doped with Sc and Te. Computational results indicate that the substitution of Mg with Sc as a cationic site dopant and Bi with Te as an anionic site dopant can effectively shift the Fermi level into the conduction band, leading to a significant increase in carrier concentration. Experimental results confirm the effectiveness of the co-doping, exhibiting a high power factor exceeding 20 μW cm−1 K−2 at 703 K. Furthermore, detailed micro/nanostructural characterizations revealed that doping induces a high density of point defects causing extensive lattice distortions. These lattice imperfections effectively scatter phonons, validating the achieved low thermal conductivity of 0.93 W m−1 K−1. As a result, an improved ZT value of 1.53 was obtained at 703 K in Sc 0.01 Mg 3.19 Sb 1.5 Bi 0.47 Te 0.03 bulk material. Additionally, we found that Sc doping significantly enhances mechanical properties, including elastic modulus, hardness, shear strength, and compressive strength, which is practically meaningful for its application in real device scenarios. [ABSTRACT FROM AUTHOR]

SnTe is a promising replacement for PbTe due to its non-toxicity and high thermoelectric conversion efficiency. However, it suffers from poor performance caused by the presence of tin vacancies and a wide energy gap between the light and heavy valence bands, as well as high thermal conductivity that inhibits its thermoelectric properties. In this work, complexes of in situ grown SnTe with Bi doping were synthesized by microwave wet chemical synthesis. The complex morphology of the micro-nanoparticles and the formation of holes after spark plasma sintering suppress phonon scattering and greatly reduce the lattice thermal conductivity of the system. The band structure and phonon dispersion of Bi doped SnTe were calculated by first principles, and the reasons for the improvement of electric transport properties and the decrease of thermal conductivity of SnTe were investigated, combined with mechanical properties and sound speed reduction. The effects of various mechanisms such as polycrystalline interfaces, point defects, complex morphologies, and phonon dispersion flat bands on phonon scattering are discussed in detail and the obtaining mechanism of low lattice thermal conductivity is understood. [ABSTRACT FROM AUTHOR]