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As an earth‐abundant, environment‐friendly, and cost‐effective material, tetrahedrite Cu12Sb4S13 has attracted much attention in thermoelectrics (TEs). However, the TE performance of the pristine Cu12Sb4S13 (CSS) is mediocre, thereby much improvement is required. In this work, both the electronic and phonon transports of the CSS are engineered using Ga2Te3 as a dopant. In the results, it is indicated that dual substitutions of Ga for Cu and Te for Sb not only cause the enhancement of power factor via electronic band structure tuning, but also leads to a drop in both the electronic and lattice thermal conductivities. As a result, the total thermal conductivity (κ) decreases to 0.98 W m−1 K−1 at 770 K, which is about 58% that of the pristine CSS, thus improving the TE performance with the highest dimensionless figure of merit value increasing to 0.95 for (Cu12Sb4S13)0.9(Ga2Te3)0.1 at 773 K, 1.9 times that of the pristine CSS (≈0.5 at 770 K). [ABSTRACT FROM AUTHOR]

The carrier transport mechanism in most thermoelectric semiconductors is governed by conventional band transport, however, there is an exception in ternary Cu2SnSe4 (CTS) or its based counterparts in which the transport mechanism is dominated by a small polaron hoping model. The sluggish movement of the small polaron greatly suppresses the mobility of the carrier due to the strong coupling of the electron with the phonon, therefore, a proper decoupling is highly necessary. To achieve this goal, herein, InSe bonds are created by incorporating some indium into the cation vacancy in CTS, which effectively balances the transports between electron and phonon. As a consequence, both the electrical property (σ) and thermal conductivity (κ) are optimized in the sample Cu2Sn1−xInxSe4 (x = 0.1), and its thermoelectric performance improves with the highest figure of merit (ZT) of 0.5. This value is ≈52% higher than that of the pristine CTS, proving that incorporation of In in the cation vacancy in CTS is an alternative way to balance the transports between electron and phonon. [ABSTRACT FROM AUTHOR]

The rational synthesis of high‐performance thermoelectric (TE) materials guided by theoretical design is still in its infancy. Here by computationally exploiting the possibilities of materials' dopability and hence the electron–phonon transport/scattering, a new defective compound, AgGaTe2, with simultaneous Ag deficiency and isoelectronic substitution of In on Ga‐site (InGa) is predicted, and its high performance is then confirmed via experiments. Using density functional theory and density functional perturbation theory calculations, it is identified that controlled defects viz. Ag vacancy and In substitution in AgGaTe2 system can lead to extremely low lattice thermal conductivity (κL) of around 0.13 WK−1 m−1 at 850 K. This ultralow κL results from both the Ag vacancy that serves as a better rattler and the extra phonon scattering due to the defect induced internal lattice distortion (ψ). The synthesized compounds Ag0.85Ga1−xInxTe2 (x = 0–0.3) indeed achieve the extremely low κL (0.08 WK−1 m−1 for x = 0.15). As a result, the highest TE figure of merit (ZT) of 1.44 is obtained, which is the highest recorded value for silver‐based ternary chalcopyrite semiconductors to date. [ABSTRACT FROM AUTHOR]

In this work we have observed a remarkable improvement in the thermoelectric (TE) performance of In6- xSn xSe7 ( ZT = ∼0.28 at x = 0.1, 833 K) compared to that of pristine In6Se7 ( ZT = 0.015 at 640 K). This improvement is mainly attributed to the creation of active donor defects SnIn3+ as Sn(4+) is energetically favorable to In+ sites. Although Sn (2+), which generates a defect SnIn− as an acceptor when it is incorporated into the In3+ sites, has a negative effect on the transport properties, the counter effect from Sn(4+) and Sn(2+) suggests that In6Se7-based alloys are prospectively good thermoelectric candidates if their chemical compositions are well optimized. [ABSTRACT FROM AUTHOR]

In this work, we have observed the enhancement of carrier concentration in α-In2Se3 at a specific S content. This enhancement results from avoiding the annihilation of defects, such as VIn and interstitial Ini acting as donors, via the rearrangement of both the cationic and anionic disorders. Therefore, there is a remarkable improvement in electrical conductivity ( σ). For example, the sample α-In2S0.05Se2.95 perpendicular to the pressing direction ( C┴) gives the highest σ value of 5.56 × 103 Ω−1 m−1 at 923 K, while the virgin α-In2Se3 gives only 9.17 × 102 Ω−1 m−1. In addition, there are dual effects on the lattice thermal conductivity ( κL) resulting from the stabilization of the lattice structure caused by the rearrangement of defect disorder and the lattice distortion from the formation of defect SSe. Therefore, the lattice contribution ( κL) in S-incorporated α-In2Se3 remains relatively high at high temperatures. As a consequence, we have improved the thermoelectric performance, achieving a ZT value of 0.67 for α-In2S0.05Se2.95 at 923 K, which is about 2.8 times that of virgin α-In2Se3 ( ZT = 0.24 at C┴). [ABSTRACT FROM AUTHOR]

We present two series of Cu2Ga4Te7-based compounds with Zn substituting for Cu (Cu-poor) and Ga (Ga-poor), and have observed enhanced thermoelectric performance. Generally, the Seebeck coefficient ( α) and lattice thermal conductivity ( κL) increase and electrical conductivity ( σ) decreases with the Zn content increasing. The variation in electrical properties might be mainly due to the formation of antisite defects ( [ABSTRACT FROM AUTHOR]

N-type Mg2Si0.59 − xSn0.41Sb x (0 ≤ x ≤ 0.01) solid solutions were prepared by melting elemental metals in sealed tantalum tubes followed by hot pressing. The electrical conductivity, Seebeck coefficient, and thermal conductivity have been measured as a function of temperature from 300 to 770 K. The electron effective mass and electron concentration increase with increasing Sb doping amount. The Sb doping enhances the concentration of Mg vacancies, which reduces the electron concentration. The maximum dimensionless figure of merit is 0.68 at 693 K for the x = 0.005 sample. [ABSTRACT FROM AUTHOR]

Most ternary Cu‐In‐Te chalcogenides have large bandgaps and high Seebeck coefficients, hence they have received much attention in the thermoelectric (TE) community. However, it is still challenging to reduce their thermal conductivities while sustaining their electrical properties; therefore, much work needs to be done. The phonon and electronic properties in ternary CuInTe2‐based chalcogenides CuIn1−xGaxTe2:yInTe (x = 0–0.3) with in situ formed nanoscale phase InTe precipitated in the grain boundaries is synergistically regulated. This regulation reduces the lattice thermal conductivity by a factor of ≈2 compared to pristine CuInTe2, due to phonon–phonon interaction and point defect scatterings introduced in the main phase at high temperatures for samples at x ≤ 0.2, combined with the phonon blocking effect from InTe at low and middle temperatures. At the same time, the power factor enhances by 73%. As a result, the TE performance improves significantly with a peak figure of merit value of 1.22 at ≈850 K. [ABSTRACT FROM AUTHOR]

The interface stability is of great significance for maintaining the high output performance of thin‐film thermoelectric devices. Here, it is demonstrated that by introducing a Ti layer and controlling its thickness, the interface stability relating to element diffusion, contact resistance, and mechanical strength can be regulated at Bi2Te3/Cu interfaces. After heat treatment, the multilayer interface with a thickness of 270 nm for the Ti layer has a stable structure that can suppress element diffusion, maintain a low specific contact resistivity (7.49 × 10−6 Ω cm2) and obtain an excellent critical load (58.1 mN). These characteristics are achieved because the Ti film with a thickness of 270 nm can keep multilayer interface stable, maintain the interface as effective junctions, and alleviate stress release. Due to the diffusion of Cu, the Cu‐Te compounds are formatted and Cu diffusion into Bi2Te3 is generated in the interfaces. Meanwhile, the results show that the Cu diffusion into Bi2Te3 has a greater impact on contact resistance than p‐CuTe in the interface. The work provides a general method for maintaining the reliability and stability of multilayer interfaces in thin‐film thermoelectric devices. [ABSTRACT FROM AUTHOR]

Cu3SnS4 chalcogenide as a low‐cost, earth abundant thermoelectric material has recently attracted much attention. However, its Seebeck coefficient is rather low due to its metallic‐like behavior; therefore, substantial work is required to enhance its thermoelectric (TE) properties. In this work, an alternative method is proposed, that is, a regulation of the crystal structure through alloying with Cu3SbSe3. This regulation is realized by the incorporation of Sb and Se in the Cu3SnS4 host frame with an addition of Cu3SbSe3, thus altering the bond lengths (CuS and SnS) and bond angles (SCuS and SSnS), and leading to widening of the bandgap and the convergence of top valence bands. At the same time, the lattice thermal conductivity reduces by ≈50% at high temperatures, mainly triggered by the crystal structure distortion and introduced point defects. The approach of crystal structure regulation may help design the properties of other ternary CuSn(Sb)S(Se) compounds for TE applications. [ABSTRACT FROM AUTHOR]