High Thermoelectric Properties Research Articles

Unraveling the Synergistic Role of Kinks in Zig-Zag Ag2Se Nanorod Arrays for High Room-Temperature zT and Improved Mechanical Properties: Experimental and First-Principles Studies.

Flexible thermoelectric materials are usually fabricated by incorporating conducting or organic polymers; however, it remains a formidable task to achieve high thermoelectric properties comparable to those of their inorganic counterparts. Here, we present a high zT value of 1.29 ± 0.31 at room temperature in the hierarchical zig-zag Ag2Se nanorod arrays fabricated using the glancing angle deposition (GLAD) technique followed by a facile selenization process. The high zT value at 300 K is ascribed to the ultrahigh power factor of 3101 ± 252 μW/m-K2 and the reduced thermal conductivity of 0.72 ± 0.01 W/mK. Based on ab initio computational and experimental evidence, we reveal that kinked Ag2Se nanorod arrays consisting of rough interfaces modulate the lattice thermal conductivity up to 48.5% at room temperature. The modulation results from interchanging of phonon modes at kink points and enhanced scattering from a large number of rough interfaces. Further, benefiting from kinked hierarchy, a notable improvement in the mechanical performance is observed for zig-zag Ag2Se nanorods which is confirmed by nanoindentation measurements. The synergic improvement in thermoelectric and mechanical performance not only unravels a paradigm to harness thermoelectric heat but also offers deeper insights into tuning the mechanical properties of inorganic thermoelectric materials.

N-Type Nanocomposite Films Combining SWCNTs, Bi2Te3 Nanoplates, and Cationic Surfactant for Pn-Junction Thermoelectric Generators with Self-Generated Temperature Gradient Under Uniform Sunlight Irradiation.

Flexible thermoelectric generators (TEGs) with pn-junction single-walled carbon nanotube (SWCNT) films on a polyimide substrate have attracted considerable attention for energy harvesting. This is because they generate electricity through the photo-thermoelectric effect by self-generated temperature gradient under uniform sunlight irradiation. To increase the performance and durability of the pn-junction TEGs, n-type films need to be improved as a priority. In this study, bismuth telluride (Bi2Te3) nanoplates synthesized by the solvothermal method were added to the n-type SWCNT films, including a cationic surfactant to form the nanocomposite films because Bi2Te3 has high n-type thermoelectric properties and high durability. The performances of the pn-junction TEGs were investigated by varying the heat treatment times. When the artificial sunlight was uniformly irradiated to the pn-junction TEGs, a stable output voltage of 0.47 mV was observed in the TEG with nanocomposite films heat-treated at 1 h. The output voltage decreased with increasing heat treatment time due to the decrease in the p-type region. The output voltage of TEG at 1 h is higher than that of the TEGs without Bi2Te3 nanoplates under the same conditions. Therefore, the addition of Bi2Te3 nanoplates was found to improve the performance of the pn-junction TEGs. These findings may aid in the development of facile and flexible optical devices, including photodetectors and hybrid devices integrating solar cells.

PEDOT:PSS Films With Very High Thermoelectric Properties Through Water‐Swollen Assisted Reduction With a Tetrakis(dimethylamino)ethylene Solution

AbstractThermoelectric (TE) materials have attracted significant attention because they can be used to directly harvest waste heat into electricity. Organic TE materials like poly(3,4‐ethylenedioxythiophene):poly(styrenesulfonate) (PEDOT:PSS) have advantages including high mechanical flexibility, low cost, and low intrinsic thermal conductivity. However, their TE properties are notably inferior to their inorganic counterparts. Here, PEDOT:PSS films with very high thermoelectric properties through the sequential treatments with H2SO4, water, and ethanol solution of tetrakis(dimethylamino)ethylene (TDAE) are reported for the first time. The PEDOT:PSS films can exhibit a Seebeck coefficient of 58.2 µV K−1 and electrical conductivity of 1552 S cm−1, and the corresponding power factor is 526 µW m−1 K−2. The water treatment prior to the TDAE solution treatment is crucial for the high TE properties of PEDOT:PSS films. Without the water treatment, the control PEDOT:PSS films exhibit a Seebeck coefficient of only 32.4 µV K−1 and electrical conductivity of 1124 S cm−1, and the corresponding power factor is only 118 µW m−1 K−2. The effect of the water treatment on the Seebeck coefficient is attributed to the swelling of PEDOT:PSS films, which facilitates the penetration of TDAE from solution into the polymer films and thus the reduction of PEDOT:PSS.

Stretchable and thermo-mechanical stable ionogels with high thermoelectric properties for respiratory sensing and energy harvesting

Flexible and wearable thermoelectrics have attracted much attention due to their unique capability of converting body heat into electricity. However, the trade-off between good mechanical properties and high thermopower remains a big challenge. Herein, a general concept based on synergistic ion-ion/ion–dipole interactions and chemical-physical networks to fabricate ionic thermoelectric (i-TE) ionogels with outstanding mechanical properties and ultrahigh thermoelectric performances is developed. The as-prepared ionogel demonstrates high mechanical stretchability of up to 1160 %, ultralow hysteresis of 4.6 %, tensile strength of 5.25 MPa, toughness of 22.09 MJ/m3, as well as outstanding thermo-mechanical stability and temperature tolerance from −99 to 250 °C. Importantly, the ionogel exhibits a giant ionic Seebeck coefficient (Si) up to 28.43 mV K−1, superior ionic conductivity of 35.3 mS cm−1, and impressive power factor (PF) of 2.85 mW m−1·K−2 at 90 RH%. As a result, a record high ionic thermoelectric figure of merit (ZTi) of 6.9 is obtained. Stretchable thermoelectric materials are endowed with both giant thermovoltage and ZTi is rarely achieved in previous studies. Furthermore, the application in flexible and wearable i-TE sensors and energy harvesters is demonstrated to convert heat into electricity for sensing and human body energy harvesting. Therefore, the as-prepared stretchable i-TE materials show amazing potential for advanced wearable self-powered ionotronics.

High Thermoelectric Properties Induced in Double-Layer Black Arsenene via Decoupling Thermoelectric Coefficients

High Thermoelectric Properties Induced in Double-Layer Black Arsenene via Decoupling Thermoelectric Coefficients

High thermoelectric and opto-electronic properties of Ba3NX3 (X=F, Cl) perovskite: Insights from DFT computation

Researchers are working for discovering smart and efficient materials to cope with energy crises. Amongst them, Perovskite are explored extensively by researchers owing to their role in energy harvesting. In this study, structural, elastic, electronic, optical and thermoelectric properties of halide perovskites Ba3NX3 (X = F, Cl) have been explored by using density functional theory techniques. The permissible values of tolerance factor and formation energy ensure the structural and thermodynamic stability of these compounds. Band structure calculations revealed that both materials have semiconducting nature, with the band gap of ∼2.1 eV and 1.9 eV for Ba3NF3 and Ba3NCl3 respectively. The elastic constants suggest both compounds are mechanically stable and exhibit ductile nature. Optical response is studied in the energy range of 0–40 eV of photons. The absorption peaks are observed from 2 eV to 25 eV. Furthermore, it is observed that the relaxation time for Ba3NF3 is longer than Ba3NCl3. Thermoelectric properties such as Seebeck coefficient, electrical conductivity electronic thermal conductivity and figure of merit (ZT) are obtained using BoltzTrap2 code. It is observed that for both materials Seebeck coefficient has almost same maximum value of 1.54 × 10−3 V/K at 300K. The ZT values are found to be 1.23 for Ba3NF3 while 0.9 for Ba3NCl3 at 700K. This work demonstrates that these halides perovskites have a lot of potentiality to prove themselves as best candidates for solar cells and for thermoelectric devices.

3D Printing Elastocaloric TiNiCu Thermoelectric Shape Memory Alloys.

The development of new thermoelectric conversion and cooling materials is an important means of addressing global climate and heat emissions in the future. While heavy and toxic elements like tellurium and lead are traditionally used to make thermoelectric materials with poor mechanical properties, recent decades have seen a gradual push towards greener and more sustainable alternatives. One such potential alternative material for thermoelectric and thermal management applications would be the Nitinol (TiNi) shape memory alloy, due to their superior mechanical properties. In this study, we have investigated the use of 3D melt printing techniques that can be used to achieve thermoelectric performance and efficiency of elastic memory alloys below 500 °C. The electrical and thermal properties of TiNiCu materials and their relation to morphology were investigated. All the alloys show similar effect sizes, their fatigue behavior is however different. By adjusting the composition of Ti and Ni elements and we have obtained memory alloys with high thermoelectric properties, with a 50% increase in power factor and a 100% increase in ZT values.

Simultaneously enhancing the mechanical and thermoelectric properties of diketopyrrolopyrrole-thiophene based conjugated polymers through dynamic hydrogen-bonding

Remarkable progress has been made in the development of thermoelectric materials based on diketonepyrrolopyrrole-thiophene (DPPT). However, achieving DPPT polymers with both high thermoelectric and mechanical properties remain a challenge. In this study, thymine groups, which are beneficial for the formation of intermolecular hydrogen bonds, were introduced into the side chains of DPPT, and a series of polymers (PDPPT-x) with different amount of thymine groups (x is the molar ratio of thymine side chains) were synthesized and characterized. The introducing thymine groups can regulate the self-assembly of conjugated polymers, effectively enhancing the crystallinity and molecular packing order, and thereby improve the charge carrier mobility. Additionally, the formed dynamic hydrogen-bonding networks by the thymine groups possess a moderate strength that can alleviate applied pressure and enhance the flexibility. Among these polymers, PDPPT-5 exhibited superior performance with excellent flexibility demonstrated by its elongation at break (up to 19.8 %), surpassing that of PDPPT-0 by a power factor of 2.2. In addition, the incorporation of 5 % amount of thymine groups can enhance the interchain interactions, thereby improving the crystallinity of the polymers and consequently enhancing the carrier mobility (4.26 × 10-3 cm2 V−1 s−1 for PDPPT-5 compared to 1.14 × 10-3 cm2 V−1 s−1 for PDPPT-0). Upon doping with FeCl3 at room temperature, the power factor of PDPPT-5 is about twice that of PDPPT-0. These results suggest that incorporating hydrogen bonding is a highly effective strategy for enhancing both the thermoelectric and mechanical properties of conjugated polymer-based thermoelectric materials.

Weak interlayer interactions and nearly temperature independent electrical transport in p-type 1T′-MoTe2/Sb2Te3 superlattice-like films

Thermoelectric superlattices (SLs) are one of the important focuses in the thermoelectric field due to their ordered stacking structure and the potential to obtain extremely high thermoelectric performance. To understand the critical effects of interlayer interactions, this work fabricates p-type (1T′-MoTe2)x(Sb2Te3)y SLs and investigates their electrical properties as functions of SL period and temperature. The results discovered that the weak interlayer interactions could be driven by both the small work function difference and temperature. This brings forth hole donation and energy filtering and leads to increased hole density and the carrier effective mass of (1T′-MoTe2)x(Sb2Te3)y SLs. Strikingly, the SL structure is beneficial for achieving temperature independent electrical properties, owing to the temperature driven interlayer interaction. Several SLs acquire the largest average power factor among all SLs, which is about 1.10 mWm−1K−2 within 300∼473 K, favorable for thermoelectric applications near room temperature. This work points out the beneficial effect of the SL structure on obtaining high thermoelectric properties in a wide temperature range.

Largely Enhanced Thermoelectric Performance of Flexible Ag2Se Film by Cationic Doping and Dual-Phase Engineering.

Recent studies have shown that silver selenide is a promising thermoelectric material at room temperature. Herein, flexible films with a nominal composition of (Ag1-xCux)2Se are prepared by a simple and efficient one-pot method combined with vacuum-assisted filtration and hot pressing. The thermoelectric properties of the films are regulated by both cationic doping and a dual-phase strategy via a wet chemical method. As the x increases, not only Cu is doped into the Ag2Se, but different new phases (CuAgSe and/or CuSe2) also appear. The (Ag1-xCux)2Se film with x = 0.02 composed of Cu-doped Ag2Se and CuAgSe shows a high PF of ∼2540 μW m-1 K-2 (ZT ∼ 0.90) and outstanding flexibility at room temperature. The high thermoelectric properties of the film are due to the effect of Cu doping and the CuAgSe phase, including the increase in electrical conductivity caused by doping, the enhanced phonon scattering at the Ag2Se/CuAgSe interface, and the interaction between the energy filtering effect and the doping effect. In addition to the high output performance (PDmax = 28.08 W m-2, ΔT = 32.2 K), the flexible device assembled with the (Ag0.98Cu0.02)2Se film also has potential applications as a temperature sensor.

Bacterial Cellulose-Based ionogels with synergistically enhanced mechanical and thermoelectric performances for low-grade heat harvesting

Ionogels have a bright prospect for low-grade heat harvesting due to their advantages of non-volatility and high thermal stability. However, it is still challenging to develop ionogels with mechanical robustness and high thermoelectric properties. This work reports a carboxymethylated and Na+ doped bacterial cellulose-based ionogel (CBCIG-Na) with synergistically increased mechanical and thermoelectric performances. The enhancement of thermoelectric properties of ionogels is mainly attributed to the increase of ion transport pathways and the mobility difference between anions and cations in ionic liquid. After the modification, the CBCIG-Na ionogel with 0.5 mol% Na+ (CBCIG-Na0.5%) exhibits high Seebeck coefficient (45.02 mV K−1), ionic conductivity (21.2 mS cm−1) and ionic power factor (4296.82 μW m−1 K−2) when the relative humidity (RH) is 85 %. This is the highest ionic power factor ever reported for bacterial cellulose-based ionogels. Moreover, the CBCIG-Na0.5% shows high tensile strength (7.69 MPa) due to the larger 3D fiber network and enhanced intermolecular force, obvious adhesivity (9.28 kPa) and high transparence (76 %). After that, a flexible i-TE device containing 5 legs and packaged with polydimethylsiloxane (PDMS) was constructed. A high thermovoltage of 264.36 mV is generated when wearing the i-TE device (5 legs) on the forearm at room temperature (ΔT = 1.2 K). The outstanding performances, environmentally friendly and low-cost characters of CBCIG-Na0.5% ionogel indicating its great potential for low-grade heat harvesting.

Developing Air-Stable n-Type SWCNT-Based Composites with High Thermoelectric and Robust Mechanical Properties for Wearable Electronics.

Flexible organic thermoelectric generators are gaining prominence in wearable electronics, leveraging body heat as an energy source. Their advancement is hindered by the scarcity of air-stable n-type organic materials with robust mechanical properties. This study introduces two new polymers (HDCN4 and HDCN8), created through polycondensation of paraformaldehyde and diamine-terminated poly(ethylene glycol) (PEGDA) with molecular weights of 4000 and 8000 g/mol into single-walled carbon nanotubes (SWCNTs). The resulting HDCN4/SWCNT and HDCN8/SWCNT composites show impressive power factors of 225.9 and 108.2 μW m-1 K-2, respectively, and maintain over 90% in air for over four months without encapsulation. The HDCN4/SWCNT composite also demonstrates significant tensile strength (33.2 MPa) and flexibility (up to 10% strain), which is currently the best mechanically n-type thermoelectric material with such a high power factor reported in the literature. A thermoelectric device based on HDCN4/SWCNT generates 4.2 μW of power with a 50 K temperature difference. Additionally, when used in wearable temperature sensors, these devices exhibit high mechanical reliability and a temperature resolution of 0.1 K. This research presents a viable method to produce air-stable n-type thermoelectric materials with excellent performance and mechanical properties.

High thermoelectric properties in polycrystalline SnSe materials realized by rare earth halide Co-doping

SnSe materials have garnered significant interest due to the intrinsic low thermal conductivity. However, its limited electrical conductivity hinders their practical implementation. This study achieved a high ZT value of 1.40 at 773 K in the samples of n-type polycrystalline SnSe0.95 + x wt% SmCl3 + y wt% ErCl3 (x = 0, 0.75, 1.0, 1.25, and 1.5; y = 0, 0.0675, 0.125, and 0.25) since (SmCl3, ErCl3) co-doping decoupled the electrical-thermal transport properties. First, the released electron carrier concentration due to SmCl3 doping enhanced the electrical transport properties. The SnSe0.95 + 1.25 wt% SmCl3 sample exhibited a high power factor of 563 μWm−1K−2 at 773 K. Then, the lattice thermal conductivity markedly decreased with further ErCl3 doping due to the high-density dislocations and coherent boundary, resulting in effective the phonon scattering. Additionally, the special microtopography was conducive to the decreased lattice thermal conductivity. Therefore, the SnSe0.95 + 1.25 wt% SmCl3 + 0.125 wt% ErCl3 sample achieved a low lattice thermal conductivity value of 0.28 Wm−1K−1 at 773 K. Simultaneously, the (SmCl3, ErCl3) co-doped samples maintained the electrical transport properties than the SmCl3-doped samples. Consequently, the SnSe0.95 + 1.25 wt% SmCl3 + 0.125 wt% ErCl3 sample obtained a peak ZT value of 1.40 at 773 K and a competitive average ZT value of 0.37 from 323 to 773 K, and a theoretically calculated conversion efficiency reached 7.2%, which can be applied in the deep space for power generation. This strategy can be utilized to optimize the thermoelectric performance of other thermoelectrical material systems.

High Thermoelectric Performance and Flexibility in Rationally Treated PEDOT:PSS Fiber Bundles

Organic thermoelectric fibers have great potential as wearable thermoelectric textiles because of their one-dimensional structure and high flexibility. However, the insufficient thermoelectric performance, high fabrication cost, and mechanical fragility of most organic thermoelectric fibers significantly limit their practical applications. Here, we employ a rapid and cost-effective wet-spinning method to prepare dimethyl sulfoxide-doped poly(3,4-ethylenedioxythiophene):poly(styrene sulfonate) (PEDOT:PSS) fiber bundles, followed by rational post-treatment with concentrated sulfuric acid (98% H2SO4) to enhance their thermoelectric performance. The wearable fiber bundles composed of multiple individual PEDOT:PSS fibers have effectively reduced resistance and overall high tensile strength and stability. Rational treatment with H2SO4 partially removes excessive PSS, thereby increasing the electrical conductivity to 4464 S cm‒1, while the parallel bundle is also a major factor in improving the power factor of up to 80.8 μW m‒1 K‒2, which is super-competitive compared with those of currently published studies. Besides, the thermoelectric device based on these fiber bundles exhibits high flexibility and promising output power of 2.25 nW at a temperature difference of 25 K. Our work provides insights into the fabrication of all-organic flexible high-conductivity textiles with high thermoelectric properties.Graphical

Fabrication and Characterization of Silicon-Based Antimonene Thin Film via Electron Beam Evaporation.

Antimonene has attracted much attention due to its excellent characteristics of high carrier mobility, thermoelectric properties and high stability. It has great application prospects in Q-switched lasers, laser protection and spintronics. At present, the epitaxy growth of antimonene mainly depends on molecular beam epitaxy. We have successfully prepared antimonene films on silicon, germanium/silicon substrates for the first time using electron beam evaporation coating and studied the effects of the deposition rate and substrate on the preparation of antimonene; film characterization was performed via confocal microprobe Raman spectroscopy, via X-ray diffraction and using a scanning electron microscope. Raman spectroscopy showed that different deposition rates can lead to the formation of different structures of antimonene, such as α phase and β phase. At the same time, it was found that the growth of antimonene is also affected by different substrates and ion beams.

A New N‐Type High Entropy Semiconductor AgBiPbSe2S with High Thermoelectric and Mechanical Properties

AbstractExploring N‐type High‐entropy materials with both high thermoelectric and mechanical properties is highly desirable for all‐high‐entropy thermoelectric generators (TEGs) since the thermoelectric and mechanical properties of N‐type one are largely behind its P‐type counterparts. Herein, a new rock‐salt structure N‐type high entropy thermoelectric AgBiPbSe2S is introduced with a bandgap of ≈0.43 eV. The atomic radii difference of each component results in a large lattice distortion of 0.246, leading to a low thermal conductivity of 0.36 W m−1 K−1 at 823 K. The figure of merit (ZT) reaches 0.6 for AgBiPbSe2S at 823 K. Moreover, Ag2Se precipitates are included in AgBiPbSe2S to filter low energy carriers for high Seebeck coefficients and to scatter phonons with nanoscale wavelength for ultralow lattice thermal conductivities. Consequently, a peak ZT of ≈1.18 at 823 K and an average ZT of 0.60 at 400–823 K are obtained for Ag1.02BiPbSe2S. More importantly, high mechanical properties are also obtained in Ag1.02BiPbSe2S, of which the Vickers hardness and flexural strength are ≈209 Hv and 32 MPa, respectively, originating from the enhanced lattice friction by chemical short‐range disorder (i.e., high entropy effect) and dispersion strengthening caused by Ag2Se nanoprecipitates.

Realizing high mechanical and thermoelectric properties of N-type Bi2Te2.7Se0.3 ingots through powder sintering and carrier concentration regulation

Bi2Te3-based crystal ingots produced by zone melting (ZM) are the most widely used materials to manufacture commercial thermoelectric (TE) devices. However, the poor mechanical properties of such crystalline materials limit the production of small-scale devices. While processability can be improved by powder metallurgy (PM), it also leads to the deterioration of the TE properties due to the donor-like effect of the introduced defects and grain boundaries. Thus, additional efforts towards re-optimizing doping are required. Here, we report a PM method to improve the mechanical properties of Bi2Te3-based TE materials through the crushing and hot pressing of Bi2Te3 ingots obtained by ZM. Besides, we demonstrate the TE properties of n-type Bi2Te2.7Se0.3 (BTS) to be remarkably improved by Cu doping, which enables optimization of the carrier concentration and enhances phonon scattering at heterointerphases thus increasing the Seebeck coefficient and reducing thermal conductivity. Overall, optimized materials reach dimensionless TE figures of merit (ZT) up to 1.16 at 408 K, i.e. 45% higher than that of state-of-the-art BTS, and an average ZT value of 1.08 in the temperature range of 300–473 K.

High-performance Bi0.4Sb1.6Te3 alloy prepared by a low-cost method for wearable real-time power supply and local cooling

Manufacturing low-cost, high-performance thermoelectric (TE) modules is essential for power generation and cooling. However, traditional fabrication methods (zone melting and hot pressing) are time-consuming and expensive, and the fabricated Bi2Te3-based materials have unsatisfied performance. Herein, Bi0.4Sb1.6Te3 alloys with high TE properties were prepared using cold pressing and thermal annealing processes. This preparation process is simple, time saving, and suitable for large-scale promotion. The annealing process induces the formation of pores within the grain interface, which effectively scatters low-energy charge carriers and enhance the phonon scattering. Although the electrical properties is reduced, the improved Seebeck coefficient compensates for the deteriorated electrical properties. Meanwhile, the thermal conductivity is significantly reduced. Eventually, a peak ZT of ∼1.27 is achieved at 333 K. The TE modules assembled with our Bi0.4Sb1.6Te3 alloy exhibit high output and cooling performance, with an output power density of 12.62 mW/cm2 with a temperature difference of 30 K. Furthermore, the TE module can be used for the active cooling of human skin and achieve a cooling effect of ∼8.0 °C. These results indicate that our samples are suitable for the preparation of commercially applicable TE modules and as power sources for next-generation wearable electronic devices.

Two-dimensional Mo1-xB2 with ordered metal vacancies obtained for advanced thermoelectric applications based on first-principles calculations.

The study and development of high thermoelectric properties is crucial for the next generation of microelectronic and wearable electronics. Derived from the recent experimental realization of layers of transition metal molybdenum and boride, we report the theoretical realization of advanced thermoelectric properties in two-dimensional (2D) transition metal boride Mo1-xB2 (x = 0, 0.05, 0.10, 0.125, 0.15)-based defect sheets. The introduction of metal vacancies results in stronger d-p exchange interactions and hybridization between the Mo-d and B-p atoms. Meanwhile, the ordered metal vacancies enabled transition metal borides (n-type Mo0.9B2) to widen the d-bandwidth and raise the d-band center, leading to a relatively high carrier mobility of 3262 cm2 V-1 s-1 and conductivity twice that of a bug-free n-type MoB2 layer, which indicates that it presents good electronic and thermal transport properties. Furthermore, investigations of the thermoelectric performance exhibit a maximum ZT of up to 3.29, which is superior to those of currently reported 2D materials. Modulation by defect engineering suggests that 2D transition metal boride sheets with ordered metal vacancies have promising applications in microelectronics, wearable electronics and thermoelectric devices.

Realizing High Thermoelectric Properties in Bi2S3 Bulk via Band Engineering and Nanorods Compositing.

Bismuth sulfide is a promising thermoelectric material because of its low cost and toxicity; however, its low electrical conductivity limits its thermoelectric properties. In this study, Bi2S3+x wt% HfCl4 (x = 0, 0.25, 0.5, 0.75, and 1.0) bulk samples are fabricated using a combination of melting and spark plasma sintering. The microstructures, electronic structures, and thermoelectric properties of the composites are characterized. The results of electronic structure calculations show that doping with HfCl4 produces an impurity energy level that narrows the bandgap and allows the Fermi energy level to enter the conduction band, leading to a favorable increase in carrier concentration. By regulating the HfCl4 doping concentration, the electrical conductivity of the 0.75wt% doped sample reaches 253Scm-1 at 423K and its maximum ZT value is 0.47 at 673K. Moreover, the sample is compounded with Bi2S3 nanorods prepared by the hydrothermal method, reducing thermal conductivity by 30% due to the introduction of additional interfaces and pores. This resulted in a final ZT value of 0.61 at 673K, which is approximately eight times higher than that of pure Bi2S3. This step-by-step optimization approach provides a valuable methodology for enhancing the performance of other thermoelectric material systems.