Average ZT Value Research Articles

Enhancing Thermoelectric and Mechanical Properties of p-Type (Bi, Sb)2Te3 through Rickardite Mineral (Cu2.9Te2) Incorporation

Bi2Te3-based alloys are widely utilized in Peltier coolers owing to their highest thermoelectric performance at near-room-temperatures. However, their peak dimensionless thermoelectric figure of merit, zT, is limited to a narrow temperature window due to minority carrier excitation emerging upon heating at around 400 K. Here, we show how this issue can be overcome by incorporating a synthetic rickardite mineral, Cu3–xTe2, in p-type (Bi, Sb)2Te3. The significant enhancement of the electronic and thermal properties could be achieved due to small Cu incorporation into the crystal structure of (Bi, Sb)2Te3 and homogeneous precipitation of Cu3–xTe2 at the grain boundaries. This leads to a high average zT value (zTave) of 1.22 between 350 and 500 K for two compositions, Bi0.5Sb1.5Te3 (BST-5) and Bi0.3Sb1.7Te3 (BST-3), with peak zT values of 1.32 at 467 K and 1.30 at 400 K, respectively. These high zT values result in a considerably high maximum device ZT of ca. 1.15 and a theoretical efficiency of up to 7% between 325 and 525 K. Additionally, room-temperature micro-hardness is substantially improved, which is desirable for constructing reliable and durable thermoelectric modules.

Enhancing the Thermoelectric Performance of GeSb4Te7 Compounds via Alloying Se.

Ge-Sb-Te compounds (GST), the well-known phase-change materials, are considered to be promising thermoelectric (TE) materials due to their decent thermoelectric performance. While Ge2Sb2Te5 and GeSb2Te4 have been extensively studied, the TE performance of GeSb4Te7 has not been well explored. Reducing the excessive carrier concentration is crucial to improving TE performance for GeSb4Te7. In this work, we synthesize a series of Se-alloyed GeSb4Te7 compounds and systematically investigate their structures and transport properties. Raman analysis reveals that Se alloying introduces a new vibrational mode of GeSe2, enhancing the interatomic interaction forces within the layers and leading to the reduction of carrier concentration. Additionally, Se alloying also increases the effective mass and thus improves the Seebeck coefficient of GeSb4Te7. The decrease in carrier concentration reduces the carrier thermal conductivity, depressing the total thermal conductivity. Finally, a maximum zT value of 0.77 and an average zT value of 0.48 (300-750 K) have been obtained in GeSb4Te5.5Se1.5. This work investigates the Raman vibration modes and the TE performance in Se-alloyed GeSb4Te7 sheddinglight on the performance optimization of other GST materials.

Decoupled electron and phonon transport in thermoelectric GeTe compounded with multi-walled carbon nanotubes

With developing of thermoelectric (TE) performance, GeTe-based TE materials present great promising application at medium temperatures as a replacement for toxic PbTe. However, the further improvement of TE properties is severely constrained by the coupling of electron and phonon transport. In this study, we achieve decoupled electron and phonon transport by effectively creating a special phase boundary to scatter phonon but transmit electron by implanting multi-walled carbon nanotubes (MWCNTs) into Bi-doped GeTe. With the help of this decoupling mechanism, the power factor is effectively improved and reaches up to ∼4482 μW−1 m−1 K−2 at 673 K while the thermal conductivity shows an obvious drop to ∼1.27 W m−1 K−1 at 723 K, leading to an impressive increase in zT to a maximum value of ∼2.3 at 723 K. In particular, a competitive average zT value of ∼1.43 in the temperature range of 323–773 K is obtained, which is at a high level in lead-free GeTe-based materials. Our method could be used as a guidance for the decoupling of electron and phonon transport in other TE materials.

Combinatorial screening via high-throughput preparation: Thermoelectric performance optimization for n-type Bi–Te–Se film with high average zT > 1

Thermoelectric materials have drawn extensive interest due to the direct conversion between electricity and heat, however, it is usually a time-consuming process for applying traditional “sequential” methods to grow materials and investigate their properties, especially for thermoelectric films that typically require fine microstructure control. High-throughput experimental approaches can effectively accelerate materials development, but the methods for high-throughput screening of the microstructures require further study. In this work, a combinatorial high-throughput optimization solution of material properties is proposed for the parallel screening and optimizing of composition and microstructure, which involves two distinctive types of high-throughput fabrication approaches for thin films, along with a new portable multiple discrete masks based high-throughput preparation platform. Thus, Bi2Te3–xSex thin film library with 196 throughputs for locating the optimized composition is obtained in one growth cycle. In addition, another thin film library composed of 31 materials with traceable process parameters is built to further investigate the relationship between microstructure, process, and thermoelectric performance. Through high-throughput screening, the Bi2Te2.9Se0.1 film with (00l) orientation is prepared with a peak zT value of 1.303 at 353 K along with a high average zT value of 1.047 in the interval from 313 to 523 K. This method can be also extended to the discovery of other functional thin films with a rapid combinatorial screening of the composition and structure to accelerate material optimization.

Enhancement of Thermoelectric Performance for InTe by Selective Substitution and Grain Size Modulation

The different masses, ionic radii, and chemical valences of the nonequivalent crystallographic sites of thermoelectric (TE) compounds provide an effective way to modulate the thermoelectric performance by selective substitution. In this work, the selective substitution of In+ by Pb for the binary InTe material monotonically reduces the carrier concentration, which is greatly beneficial to the mechanism investigation of serious grain boundary scattering (GBS). This is the first time this point has been mentioned with regard to InTe material. As a result, we found that GBS was dominated by the grain size when the carrier concentration was higher than 0.7 × 1019 cm−3 but was inversely governed by the carrier concentration when the carrier was situated at a lower density. In particular, the occupation of Pb on the targeted In+ site could further reduce the lattice thermal conductivity. Finally, In0.9999Pb0.0001Te achieved the improved power factor and average zT value, which could contribute to high-power generation below a medium temperature. This effect of increasing the carrier concentration on the suppression of GBS sheds light on the possibility of improving electron mobility by increasing the carrier concentration.

Chemical bonding engineering for high-symmetry Cu2S-based materials with high thermoelectric performance

Liquid-like materials have gained notable attention in thermoelectrics due to their ultralow lattice thermal conductivity and tunable electrical properties. Particularly, Cu2S-based materials have the advantages of earth abundant and environmentally friendly constituents, which have the great potential for industry applications. However, Cu2S undergoes a series of phase transitions above room temperature and only the high temperature cubic phase (above 700 K) exhibits desirable thermoelectric properties, leading to the low averaged thermoelectric performance. Herein we theoretically and experimentally demonstrated that the phase transition temperature can be strongly suppressed by tuning the chemical bonding in Mn-doped Cu2S, which effectively move the high-symmetry cubic phase to a much low-temperature regime. The weakened chemical bonding facilitates the formation of Cu vacancies and thus improves the hole concentrations for optimized electrical transports. Furthermore, the lattice thermal conductivity is suppressed due to the reduced sound velocity by lattice softening and the enhanced phonon scattering by point defects. As a total result, high average power factors of 6.13 μW cm−1 K−2 and average zT values of 0.44 are obtained in the temperature range of 423 to 723 K, both of which outperform most Cu2S-based materials reported so far. The present study corroborates that chemical bonding engineering can serve as a scaffold for regulating the phase structures and transport properties in thermoelectric materials.

Defect Reconfiguration in Hole-Doped PbSe via Minute Te Doping for Significantly Enhanced Thermoelectric Performance

Rich defects near the percolation threshold of dilute solid solutions are of fundamental interest to thermoelectric research. Sn-substituted Pb0.98Na0.02Se (1 mol %) is a typical example that demonstrates how various defects induce intriguing transport phenomena. Unfortunately, the presence of Pb vacancies severely degrades the carrier mobility of samples, and the thermoelectric figure of merit ZT is only marginally improved. In this study, we show that Pb vacancies are effectively inhibited by a facile defect reconfiguration strategy. This is achieved by doping a dilute amount of Te at Se sites of Pb0.97Sn0.01Na0.02Se, where the interstitial Sn ions are pulled back to Pb sites as revealed by the X-ray photoelectron spectroscopy analysis and the positron annihilation test. Consequently, Pb vacancies get occupied, and the room temperature carrier mobility is remarkably recovered from 2.8 to 70 cm2 V–1 s–1 upon 3 mol % Te doping. Moreover, Te doping reinforces phonon scattering by strain and mass field fluctuations. The lattice thermal conductivity at 300 K goes down to ∼1.7 W m–1 K–1 for Pb0.97Sn0.01Na0.02Se0.94Te0.06, which is ∼32% lower than that of the Pb0.97Sn0.01Na0.02Se control sample. Altogether, the average ZT value of Pb0.97Sn0.01Na0.02Se between 300 and 773 K is doubled upon 6 mol % Te doping.

Microstructural Manipulation for Enhanced Average Thermoelectric Performance: A Case Study of Tin Telluride

Achieving a high average figure of merit in a low-cost/toxic compound, tin telluride (SnTe), is crucial for thermoelectric applications. Introducing gap-like structures into the rock–salt matrix once elucidated a large potential; however, the poor quantity and controllability of the planar defects become the drawbacks. Here, we demonstrate, by electron microscopy and X-ray diffraction, that dense planar cationic vacancies can be produced in Sb2Te3(Sn1–xGexTe)8 samples for the first time, leading to an effective targeted solution. On the basis of the optimized lattice matrix, a low room-temperature lattice thermal conductivity of ∼0.7 W m–1 K–1 (25% of pristine SnTe) can be achieved. Additionally, the first-principles calculation result reveals that the value of density-of-state effective mass is increased after manipulating the local cation matrix, resulting in an outstanding power factor of ∼2.5 mW m–1 K–2 at 723 K when x = 0.2. Eventually, a competitive maximum figure of merit ZTmax of ∼1.3 at 723 K and an excellent average ZT value of ∼0.78 at 323–773 K are simultaneously realized in Sb2Te3(Sn0.8Ge0.2Te)8. This pioneered study about manipulating gap-like structures and its effects on the transport properties of SnTe-based materials would also provide a promising alternative for pursuing other high ZTave compounds in the future.

High performance of Mg3Bi1.5Sb0.5 based materials for power generation: Revealing the counter-intuitive effect of tuning Bi content on the thermoelectric properties

Recently, Mg3Sb2-xBix alloys have attracted intensive attention, with the aim of maximizing the electrical transport performance via donor element doping, increasing the grain size, as well as electronic band structure engineering. However, less attention has been paid to other significant factors, like how these intrinsic point defects and accompanied secondary phases influence thermoelectric properties. In this study, the microstructure and thermoelectric transport properties of Mg3.2Sb0.5Bi1.495-xTe0.005 (x = 0 ∼ 0.2) compounds were systematically investigated, where tuning the Bi content shows the counter-intuitive impact on the thermoelectric properties. It was found that the Bi-poor environment associated with Bi impurities facilitated the increment of cation vacancy formation energy and then increased the carrier concentration, leading to the enhancement of power factor. Simultaneously, the reduction of Bi-rich second phase content weakened the carrier scattering by grain boundaries whereas high carrier mobility was maintained. Moreover, the bipolar thermal conductivity decreased obviously due to the increased majority carrier concentration to suppress the intrinsic excitation. The synergistic optimization pushes the average ZT value (300–573 K) up to 0.95 in the Mg3.2Sb0.5Bi1.295Te0.005 sample. Moreover, the calculated single-leg conversion efficiency is increased up to 9.7% with the hot-side temperature of 573 K, as the record-high value in this system.

Electrical property enhancement and lattice thermal conductivity reduction of n-type Mg3Sb1.5Bi0.5-based Zintl compound by In&Se co-doping

Mg3Sb1.5Bi0.5-based Zintl compounds have attracted extensive attention as potential thermoelectric materials due to their earth-abundant elements. However, pure and intrinsic Mg3Sb1.5Bi0.5 manifests a poor thermoelectric performance because of its low electrical conductivity of about 3 × 102 S/m at room temperature. In this work, In and Se co-doping was carried out to optimize the thermoelectric performance of n-type Mg3Sb1.5Bi0.5-based material. The experimental results revealed that the carrier concentration and mobility of Mg3Sb1.5Bi0.5 significantly increased after In and Se co-doping, leading to an improvement of power factor. Simultaneously, lattice thermal conductivity was significantly reduced due to the large mass difference between In and Mg. A maximum zT of 1.64 at 723 K was obtained for the Mg3.17In0.03Sb1.5Bi0.49Se0.01 sample. And an average zT value of about 1.1 between 300 and 723 K was achieved, which insures its possible application at medium temperature range as a non-toxic and low-cost TE material.

Charge Balanced Vacancy Engineering to Enhance the Thermoelectric Properties of GeMnTe2

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.

Intrinsically Low Lattice Thermal Conductivity and Anisotropic Thermoelectric Performance in In‐doped GeSb2Te4 Single Crystals

AbstractLayer‐structured GeSb2Te4 is a promising thermoelectric candidate, while its anisotropy of thermal and electrical transport properties is still not clear. In this study, Ge1–xInxSb2Te4 single crystals are grown by Bridgman method, and their anisotropic thermoelectric properties are systematically investigated. Lower electrical conductivity and higher Seebeck coefficient are observed in the c‐axis due to the higher effective mass in this direction. Intrinsically low lattice thermal conductivity is also observed in the c‐axis due to the weak chemical bonding and the strong lattice anharmonicity proved by density functional theory calculation. Indium doping introduces an impurity band in the bandgap of GeSb2Te4 and leads to the locally distorted density of states near the Fermi level, which contributes to enhanced Seebeck coefficient and improved power factor. Ultimately, a peak zT value of 1 at 673 K and an average zT value of 0.68 within 323–773 K are obtained in Ge0.93In0.07Sb2Te4 along the c‐axis direction, which are 54% and 79% higher than that of the pristine GeSb2Te4 single crystal, respectively. This study clarified the origin of intrinsic low lattice thermal conductivity and anisotropy transport properties in GeSb2Te4, and shed light on the performance optimization of other layered thermoelectric materials.

Optimized electronic properties and nano-structural features for securing high thermoelectric performance in doped GeTe.

Recently, thermoelectric (TE) materials have been attracting great attention due to their improved capability to convert heat directly into electricity. PbTe-based TE materials are among the most competitive ones; however, lead toxicity limits their potential applications. Thus, the current focus in the field is on the discovery of lead-free analogues. GeTe is considered to be a promising candidate, however, its thermoelectric performance is limited by a non-ideal band structure and intrinsic Ge vacancies. In this work, GeTe was co-doped with Bi, Zn, and In. Initial doping with Bi enhances the performance by tuning the electronic properties and bringing down the thermal conductivity. Subsequent Zn doping permits to maintain the high power factor by increasing carrier mobility and reducing carrier concentration. Additionally, Zn incorporation lowers thermal conductivity and, thus, increases the performance. Subsequent In doping in (Ge0.97Zn0.02In0.01Te)0.97(Bi2Te3)0.03 reduces thermal conductivity even further and makes this material the best performing one. Scanning transmission electron microscopy shows the presence of nano twinning, defect layers, and dislocation bands that contribute to the suppression of the lattice thermal conductivity. A peak zT value of 2.06 and an average zT value of 1.30 have been achieved in (Ge0.97Zn0.02In0.01Te)0.97(Bi2Te3)0.03. These results are among the best state-of-the-art thermoelectric materials.

Integrated measurement of thermoelectric properties for filamentary materials using a modified hot wire method.

Thermoelectric materials have been rapidly developed due to the urgent need for the mutual conversion of thermal energy and electrical energy. Accurately measuring the thermoelectric properties of micro/nano thermoelectric materials is very important and highly required. Compared with traditional measurement methods, integrated measurement can avoid multiple sample preparations and reduce measurement errors. Herein, this work designed an improved integrated measurement method for the thermoelectric properties of microscale thermoelectric materials based on the hot wire method. The results demonstrated that the average ZT values of Pt and Ag2S wires are 0.75 × 10-3 and 0.44 × 10-3 with an uncertainty of ∼2.61%. It provides a novel way for the development of accurately measuring the thermoelectric properties of thermoelectric materials.

Controlling the Thermoelectric Behavior of La-Doped SrTiO3 through Processing and Addition of Graphene Oxide.

The addition of graphene has been reported as a potential route to enhance the thermoelectric performance of SrTiO3. However, the interplay between processing parameters and graphene addition complicates understanding this enhancement. Herein, we examine the effects of processing parameters and graphene addition on the thermoelectric performance of La-doped SrTiO3 (LSTO). Briefly, two types of graphene oxide (GO) at different oxidation degrees were used, while the LSTO pellets were densified under two conditions with different reducing strengths (with/without using oxygen-scavenging carbon powder bed muffling). Raman imaging of the LSTO green body and sintered pellets suggests that the added GO sacrificially reacts with the lattice oxygen, which creates more oxygen vacancies and improves electrical conductivity regardless of the processing conditions. The addition of mildly oxidized electrochemical GO (EGO) yields better performance than the conventional heavily oxidized chemical GO (CGO). Moreover, we found that muffling the green body with an oxygen-scavenging carbon powder bed during sintering is vital to achieving a single-crystal-like temperature dependence of electrical conductivity, implying that a highly reducing environment is critical for eliminating the grain boundary barriers. Combining 1.0 wt % EGO addition with a highly reducing environment leads to the highest electrical conductivity of 2395 S cm-1 and power factor of 2525μW m-1 K-2 at 300 K, with an improved average zT value across the operating temperature range of 300-867 K. STEM-EELS maps of the optimized sample show a pronounced depletion of Sr and evident deficiency of O and La at the grain boundary region. Theoretical modeling using a two-phase model implies that the addition of GO can effectively improve carrier mobility in the grain boundary phase. This work provides guidance for the development of high-performance thermoelectric ceramic oxides.

Optimized carrier concentration and enhanced thermoelectric properties in GeSb4-xBixTe7 materials

As the pseudo-binary alloys between GeTe and Sb2Te3, GeSbTe-based compounds are promising thermoelectric materials. Although Ge2Sb2Te5 and GeSb2Te4 have widely been studied, the thermoelectric properties of GeSb4Te7 have not been well understood yet. In this work, we design a series of GeSb4-xBixTe7 solid solutions and systematically study the variation in the crystal structure, electrical, and thermal transport properties. Alloying Bi effectively reduces the carrier concentration and, thus, enhances the Seebeck coefficient. Meanwhile, the thermal conductivity is greatly reduced via large mass fluctuations. A maximum zT of 0.69 at 550 K and an average zT value of 0.52 between 300 and 700 K have been achieved for GeSb1.5Bi2.5Te7. These findings will promote the understanding and development of GeSbTe-based thermoelectric materials.

Enhanced thermoelectric performance of N-type Bi2Te2.7Se0.3-based materials by superparamagnetic Fe3O4 nanoparticles

Magnetic particles as second phases have been extensively reported to optimize electrical and thermal transport properties in single thermoelectric (TE) matrixes. However, the comparative performance of TE substrates with different carrier concentrations that incorporates magnetic particles are lacking from literature. In this work, a small amount of Ag2Se particles was employed as a second phase for the reduction of the electrical conductivity of Bi2Te2.7Se0.3 (BTS) by constructing n-type homojunction or doping effect, and then the BTS based thermoelectric performance was studied by incorporating single-phase superparamagnetic Fe3O4 nanoparticles. A series of BTS-xwt%Ag2Se-ywt%Fe3O4 TE ingots were sintered and their transport properties were investigated. Finally, the maximum recorded ZT values were 0.78 for BTS-0.4 wt%Ag2Se and 0.72 for BTS-0.4 wt%Fe3O4, which are 1.3 times and 1.2 times higher that of the pure sample respectively. For BTS-0.4 wt%Ag2Se-0.4 wt%Fe3O4, the maximum and average ZT values were 0.89 and 0.77, representing 48% and 40% increments compared with the pure sample. This study confirms the effectiveness of superparamagnetic Fe3O4 nanoparticles in the performance improvement of TE ingots with low electrical conductivity.

Enhanced thermoelectric performance of p-type Bi2Te3-based materials by suppressing bipolar thermal conductivity

Thermal excitation causes a surge in carrier concentration in narrow bandgap semiconductors that seriously limit its application in the high-temperature zone. Therefore, suppressing bipolar thermal conductivity and broadening the application temperature zone is vitally important for commercial Bi2Te3-based thermoelectric materials. Here, Cu0.6Ni0.4 (CN) nanoparticles synthesized via hydrothermal method are introduced into Bi0.4Sb1.6Te3 (BST) commercial materials. Then, the electrical and thermal properties of BST-CN (with x wt%, x = 0, 0.1, 0.2, 0.4, BST-x-CN) materials are systematically investigated. The results exhibited that the weighted mobility could be improved and the bipolar thermal conductivity could be suppressed for all dealt samples. The maximum and average ZT (figure of merit) values were 1.3 at 393 K and 1.17 in the temperature range of 303–483 K for BST-0.1-CN sample, which exhibited an enhancement by 28.7% and 28.6% than that of the pure sample, respectively. And the optimal ZT values are attained at higher temperatures with the CN nanoparticles contents increasing. Meanwhile, the sintered technique was optimized to enhance electron transport properties, the highest room-temperature power factor of 5.08 mW/m/K2 was attained for the BST-0.1-CN cycle-2 sintered sample. And the optimal ZT value is 1.35 at 393 K for the BST-0.1-CN cycle-1 sintered sample. Finally, the results indicated that the thermoelectric performance could be improved and the application temperature zone could be broadened by suppressing bipolar thermal conductivity owing to the existence of CN nanoparticles.

Defect engineering synergistically modulates power factor and thermal conductivity of CuGaTe2 for ultra-high thermoelectric performance

• The vacancy of Cu atom can increase the band gap and reduce the sound velocity. • Cu vacancies increase the density of the samples, and significantly increase the carrier concentration. • Cu vacancies generate many defects, which scatter phonons at multiple scales and realize thermoelectric decoupling. • The highest ZT value of Cu 0.96 GaTe 2 reaches 1.23 at 823 K, and the average ZT value reaches 0.575. The ternary chalcopyrite CuGaTe 2 has emerged as a promising p -type thermoelectric material with its advantages of low cost, good stability, and non-toxic elements. However, its thermoelectric performance is limited by the intrinsic low electrical conductivity and high lattice thermal conductivity. In this work, A deficiency of Cu in Cu 1– x GaTe 2 semiconductors can be used to optimize the electrical properties by improving the carrier concentration and to reduce thermal conductivity through multi-scale phonon scattering, which is predicted and guided by the First-principles density functional theory calculations. The carrier concentration is increased to 10 20 , which compensates for the low electrical performance caused by the intrinsic low n H of CuGaTe 2 . The average power factor of Cu 0.96 GaTe 2 reaches 106.3% higher than that of the original CuGaTe 2 . In addition, the lattice thermal conductivity of the defective samples is greatly reduced at high temperatures, which is mainly due to the reduction of sound speed and phonon scattering. All the above factors contribute to the highest dimensionless figure of merit (ZT) value of 1.23 at 823 K in Cu 0.96 GaTe 2 , which is 114% higher than the pristine CuGaTe 2 , and the average ZT is 171.4% higher.

Realizing high thermoelectric performance of Cu and Ce co-doped p-type polycrystalline SnSe via inducing nanoprecipitation arrays

Thermoelectric (TE) performance of polycrystalline stannous selenide (SnSe) has been remarkably promoted by the strategies of energy band, defect engineering, etc. However, due to the intrinsic insufficiencies of phonon scattering and carrier concentration, it is hard to simultaneously realize the regulations of electrical and thermal transport properties by one simple approach. Herein, we develop Cu and Ce co-doping strategy that can not only greatly reduce lattice thermal conductivity but also improve the electrical transport properties. In this strategy, the incorporated Cu and Ce atoms could induce high-density SnSe2 nanoprecipitation arrays on the surface of SnSe microplate, and produce dopant atom point defects and dislocations in its interior, which form multi-scale phonon scattering synergy, thereby presenting an ultralow thermal conductivity of 0.275 W·m-1·K-1 at 786 K. Meanwhile, density functional theory (DFT) calculations, carrier concentration, and mobility testing reveal that more extra hole carriers and lower conducting carrier scattering generate after Cu and Ce co-doping, thereby improving the electrical conductivity. The co-doped Sn0.98Cu0.01Ce0.01Se bulk exhibits an excellent ZT value up to ~1.2 at 786 K and a high average ZT value of 0.67 from 300 to 786 K. This work provides a simple and convenient strategy of enhancing the TE performance of polycrystalline SnSe.