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Thermoelectrics are an important class of materials with great potential in alternative energy applications. In this study, two-dimensional (2D) nanoplates of the layered chalcogenides, Sb2Te3 and Bi2Te3, are synthesized and composites of the two are investigated for their thermoelectric properties. The two materials, Sb2Te3 and Bi2Te3, were synthesized as hexagonal, 2D nanoplates via a colloidal polyol route. The as-synthesized Sb2Te3 and Bi2Te3 vary drastically from one another in their lateral and vertical dimensions as revealed by scanning electron microscopy and atomic force microscopy. The single crystalline nanoplate nature is deduced by high-resolution transmission electron microscopy and selected area electron diffraction. Nanoplates have well-defined hexagonal facets as seen in the scanning and transmission electron microscopy images. The nanoplates were consolidated as an anisotropic nanostructured pellet via spark plasma sintering. Preferred orientation observed in the powder X-ray diffraction pattern and scanning electron microscopy images of the fractured pellets confirm the anisotropic structure of the nanoplates. Thermoelectric properties in the parallel and perpendicular directions were measured, revealing strong anisotropy with a significant reduction to thermal conductivity in the perpendicular direction due to increased phonon scattering at nanoplate interfaces. All compositions, except that of the 25% Bi2Te3 nanoplate composite, behave as degenerate semiconductors with increasing electrical resistivity as the temperature increases. The Seebeck coefficient is also increased dramatically in the nanocomposites, the highest reaching 210 μV/K for 15% Bi2Te3. The increase in Seebeck is attributed to energy carrier filtering at the nanoplate interfaces. Overall, these enhanced thermoelectric properties lead to a drastic increase in the thermoelectric performance in the perpendicular direction, with zT ∼ 1.26, for the 15% Bi2Te3 nanoplate composite at 450 K.

The bonding between Bi2Te3 and Si wafers is prepared under low temperature through forming Si-O-Te and Si-O-Bi. Under the irradiation of vacuum ultraviolet, oxygen radicals and ozone are formed from oxygen molecules, which produces the thin oxide layers on the wafers' surfaces. By absorbing water molecules and by dehydration-condensation reaction, the bonds of Si-O-Te and Si-O-Bi are formed. During the annealing process, Te atoms more easily diffuse into Si wafers than Bi atoms because the surface of Bi2Te3 is terminated with Te atoms. The layered crystal structure of Bi2Te3 weakens the bonding strength because only the surface layer of Bi2Te3 can bond with Si. The fabricated Bi2Te3/Si heterojunctions have the typical I-V curve of PN junctions. [ABSTRACT FROM AUTHOR]

Thermoelectric materials with high electrical conductivity and low thermal conductivity (e.g., Bi2Te3) can efficiently convert waste heat into electricity; however, in spite of favorable theoretical predictions, individual Bi2Te3 nanostructures tend to perform less efficiently than bulk Bi2Te3. We report a greater-than-order-of-magnitude enhancement in the thermoelectric properties of suspended Bi2Te3 nanoribbons, coated in situ to form a Bi2Te3/F4-TCNQ core-shell nanoribbon without oxidizing the core-shell interface. The shell serves as an oxidation barrier but also directly functions as a strong electron acceptor and p-type carrier donor, switching the majority carriers from a dominant n-type carrier concentration (∼1021 cm-3) to a dominant p-type carrier concentration (∼1020 cm-3). Compared to uncoated Bi2Te3 nanoribbons, our Bi2Te3/F4-TCNQ core-shell nanoribbon demonstrates an effective chemical potential dramatically shifted toward the valence band (by 300-640 meV), robustly increased Seebeck coefficient (∼6× at 250 K), and improved thermoelectric performance (10-20× at 250 K).

Harnessing photocatalysts to facilitate the visible-light-driven breakdown of water molecules is esteemed as a highly auspicious and ecologically sustainable approach for hydrogen production. This study aimed to improve the hydrogen production performance of single ZnO photocatalysts by preparing efficient Bi2Te3/ZnO and Bi2Se3/ZnO composite photocatalysts by microwave method. During the synthesis process, both Bi2Te3 and Bi2Se3 were fully fused and reacted with ZnO to form heterojunctions using magnetic stirring and microwave heating. The experimental results indicate a significant enhancement in the hydrogen production activity of the BT-Z and BS-Z composite photocatalysts. When the Bi2Te3 content is 5%, with a microwave temperature maintained at 135 °C and a microwave time of 90 min, the hydrogen production rate reaches 664.286 μmol∙h−1∙g−1 within 4 hr. On the other hand, when the Bi2Se3 content is 5%, with a microwave temperature maintained at 135 °C and a microwave time of 90 min, the hydrogen production rate reaches 515.306 μmol∙h−1∙g−1 within 4 hr. [ABSTRACT FROM AUTHOR]

Thermoelectric (TE) technologies offer a promising approach for directly converting skin heat into electricity for wearable electronics. Recognizing p-type Sb2Te3 and n-type Bi2Te3 as top-performing materials at room temperature, their rigid inorganic structure, with ultralow moisture permeability, poses challenges in warm and humid conditions, fostering bacterial growth and potential skin issues. To address this issue, we developed a cross-linked core−shell structure by electrodepositing Sb2Te3 (Bi2Te3) onto carbon fiber (CF). This architecture significantly improved the electrical conductivity and the Seebeck coefficient, resulting in a remarkable 300-fold increase in the power factor compared to that of pure CF. The CF/Sb2Te3 and CF/Bi2Te3 films demonstrated optimal power factors of 450 and 121 μW∙m−1∙K−2, respectively. Moreover, the fabricated films exhibited outstanding moisture permeability, over 3000 g∙m−2∙d−1, exceptional electromagnetic interference shielding efficiency approaching 93 dB, and versatility as sensors for language assistance and respiratory monitoring. These attributes underline their broad applicability, emphasizing their suitability for human health protection in diverse scenarios.

Bi2Te3‐based materials play a crucial role in solid cooling and power generation, but the rapidly deteriorated ZT with rising temperatures above 450 K severely limits further applications. Here, this paper reports a novel preparation method of annealing treatment for molten ingot, which can enhance the thermoelectric performance of n‐type Bi2Te2.4Se0.6 in a wide temperature range. Instead of conventional halides, copper is adopted to regulate the carrier concentration and grain size to optimal levels. During the process of annealing at 573 K for 4 h, the number of twins significantly increases and the grains of Cu‐doped samples become larger and more oriented. These optimizations lead to higher carrier mobility with similar carrier concentration compared with the sample without heat treatment. The synergistic effects of Cu doping and annealing treatment realize a high average ZT of 0.89 within 300–600 K in n‐type Cu0.02Bi2Te2.4Se0.6. Combined with p‐type (Bi,Sb)2Te3, the fabricated thermoelectric device exhibits a high conversion efficiency of 6.9% at a temperature difference of 300 K. This study suggests that annealing treatment is a simple and effective scheme to promote the applications of n‐type Bi2(Te,Se)3 in a wide temperature range. [ABSTRACT FROM AUTHOR]

The dual-phase competitive behavior is introduced as an effective strategy to optimize the physical and chemical properties of N-type Bi 2 Te 3 thermoelectric (TE) materials. Controllable SnTe-embedded Bi 2 Te 3 nanocomposites can be synthesized with the addition of excessive Sn into Bi 2 Te 3 by tuning the crystallization behavior under proper thermal heating temperature. Notably, the precipitation temperature of Bi 2 Te 3 increases from 473 ​K for Sn 20.9 (Bi 2 Te 3) 79.1 to 573 ​K for Sn 34.4 (Bi 2 Te 3) 65.6 , expanding the controllable temperature span for the presence of SnTe phase. The second-phase nanoprecipitate SnTe can improve electrical conductivity by competing with the Bi 2 Te 3 phase, achieving an increase of four orders of magnitude at the critical temperature of ∼500 ​K. Simultaneously, it increases the interfacial energy filtration effect between nanocrystalline grains, decoupling electrical parameters between conductivity and Seebeck coefficient. Consequently, the high power factor of ∼147 ​μW/mK2 at 650 ​K for optimized Sn 26.6 (Bi 2 Te 3) 73.4 films can be obtained, which is more than twice that of the pure Bi 2 Te 3 material. Our work demonstrates a new physical mechanism to unravel the complicated structure-property relationship by dual-phase competitive behavior during phase transition. This study fills the gap in knowledge on the effects of the SnTe phase regarding the Bi 2 Te 3 system and provides guidance for the innovative design of high-performing inorganic thermoelectrics. [ABSTRACT FROM AUTHOR]

Bi 2 Te 3 -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 Bi 2 Te 3 -based TE materials through the crushing and hot pressing of Bi 2 Te 3 ingots obtained by ZM. Besides, we demonstrate the TE properties of n-type Bi 2 Te 2.7 Se 0.3 (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. [ABSTRACT FROM AUTHOR]

Bi2Te3‐based materials have drawn much attention from the thermoelectric community due to their excellent thermoelectric performance near room temperature. However, the stability of existing n‐type Bi2(Te,Se)3 materials is still low due to the evaporation energy of Se (37.70 kJ mol−1) being much lower than that of Te (52.55 kJ mol−1). The evaporated Se from the material causes problems in interconnects of the module while degrading the efficiency. Here, we have developed a new approach for the high‐performance and stable n‐type Se‐free Bi2Te3‐based materials by maximizing the electronic transport while suppressing the phonon transport, at the same time. Spontaneously generated FeTe2 nanoinclusions within the matrix during the melt‐spinning and subsequent spark plasma sintering is the key to simultaneous engineering of the power factor and lattice thermal conductivity. The nanoinclusions change the fermi level of the matrix while intensifying the phonon scattering via nanoparticles. With a fine‐tuning of the fermi level with Cu doping in the n‐type Bi2Te3–0.02FeTe2, a high power factor of ~41 × 10−4 Wm−1 K−2 with an average zT of 1.01 at the temperature range 300–470 K are achieved, which are comparable to those obtained in n‐type Bi2(Te,Se)3 materials. The proposed approach enables the fabrication of high‐performance n‐type Bi2Te3‐based materials without having to include volatile Se element, which guarantees the stability of the material. Consequently, widespread application of thermoelectric devices utilizing the n‐type Bi2Te3‐based materials will become possible. [ABSTRACT FROM AUTHOR]

[Display omitted] Thermoelectric materials have a wide range of application because they can be directly used in refrigeration and power generation. And the Bi 2 Te 3 stand out because of its excellent thermoelectric performance and are used in commercial thermoelectric devices. However, n-type Bi 2 Te 3 has seriously hindered the development of Bi 2 Te 3 -based thermoelectric devices due to its weak mechanical properties and inferior thermoelectric performance. Therefore, it is urgent to develop a high-performance n-type Bi 2 Te 3 polycrystalline. In this work, we employed interstitial Cu and the hot deformation process to optimize the thermoelectric properties of Bi 2 Te 2.7 Se 0.3 , and a high-performance thermoelectric module was fabricated based on this material. Our combined theoretical and experimental effort indicates that the interstitial Cu reduce the defect density in the matrix and suppresses the donor-like effect, leading to a lattice plainification effect in the material. In addition, the two-step hot deformation process significantly improves the preferred orientation of the material and boosts the mobility. As a result, a maximum ZT of 1.27 at 373 K and a remarkable high ZT ave of 1.22 across the temperature range of 300–425 K are obtained. The thermoelectric generator (TEG, 7-pair) and thermoelectric cooling (TEC, 127-pair) modules were fabricated with our n-type textured Cu 0.01 Bi 2 Te 2.7 Se 0.3 coupled with commercial p-type Bi 2 Te 3. The TEC module demonstrates superior cooling efficiency compared with the commercial Bi 2 Te 3 device, achieving a Δ T of 65 and 83.4 K when the hot end temperature at 300 and 350 K, respectively. In addition, the TEG module attains an impressive conversion efficiency of 6.5% at a Δ T of 225 K, which is almost the highest value among the reported Bi 2 Te 3 -based TEG modules. [ABSTRACT FROM AUTHOR]

Topological insulators (TI) are generating increasing interest as a new state of matter and due to the potential use of topologically- protected gapless surface states in spintronic devices and quantum computing. However, challenges such as high sensitivity to the atmosphere, the low surface-to-volume ratio, and the need for various material junctions currently limit their application. Here, a novel, natural and simple approach to the fabrication of volumetric TI heterostructures that can overcome these core challenges is presented, using the example of a Bi2Te3-Te eutectic composite. The proposed method based on directional solidification of eutectic composites, enables the formation of ensembles of parallel TI-other material heterojunctions through a self-organization process. It also offers control over the heterostructures’ dimensions/refinement. Electron microscopy techniques show that the heterostructure exhibits a lamellar/layered microstructure with atomically smooth Bi2Te3ǀǀTe interfaces. Angle-resolved photoelectron spectroscopy experiments confirm the existence of metallic surface states, while Kelvin probe force microscopy depicts the formed p-n junctions. The new degrees of freedom offered here, such as control of heterojunction chemical composition, packing density, and available fabrication techniques, may facilitate large-scale customized printing of topological devices.

We have introduced an innovative method for preparing CuI-doped Bi 2 Te 3 films for the first time, which was also validated through ab initio calculations. The chemical reaction between the Cu-Bi 2 Te 3 film and iodine was conducted using the solid iodination method at room temperature. The results from X-ray diffraction and energy-dispersive spectrometry suggest that the sputtering process, followed by the solid iodination method, holds promise for synthesizing CuI-doped Bi 2 Te 3 films. Additionally, appropriately doping Bi 2 Te 3 with CuI enhances the (00l) crystal orientation, increases carrier concentration and mobility, resulting in improved electrical conductivity. Furthermore, our calculation results align with our experimental findings. An excess of substitutional CuI dopant tends to generate secondary phases, leading to alterations in the intrinsic conductivity and a reduction in the thermoelectric properties of Bi 2 Te 3. Leveraging the enhanced electrical transport properties achieved through CuI doping, the maximum power factor of the (CuI) 0.2 Bi 2 Te 2.9 film reaches approximately 2.40 × 10−3 W/mK2 at 423 K, representing a 66 % enhancement compared to that of the Bi 2 Te 2.9 film, which has a power factor of 1.44 × 10−3 W/mK2. [ABSTRACT FROM AUTHOR]

This study investigated the effects of KCl treatment on microstructure and thermoelectric properties of n-type Bi2Te2.7Se0.3 (BTS) thermoelectric materials. The innovative KCl treatment was originally intended to introduce nanopores through selective dissolution of KCl from a mixture of thermoelectric materials and KCl. However, it unexpectedly induced substantial variations in material composition and microstructure during the subsequent spark plasma sintering (SPS) process. Hydroxyl groups adsorbed on the powder surface during the dissolution resulted in the emergence of a Bi2TeO5 secondary phase within the BTS matrix after the SPS process at 450 ℃. The concentration of Bi2TeO5 increased with an increase in the KCl content. Furthermore, a remarkable grain growth occurred at low KCl concentrations, likely due to the liquid-phase formation in a Te-rich composition during SPS. However, excessive Bi2TeO5 at higher KCl concentrations hindered grain growth. These variations in the microstructure had complex effects on electrical properties: The TeBi antisite defects increased the electron concentration, and Bi2TeO5 reduced electron mobility. Additionally, the lattice thermal conductivity decreased due to the presence of Bi2TeO5, from 0.8 W∙m−1∙K−1 at 298 K for the pristine BTS to 0.6 W∙m−1∙K−1 at 298 K for BTS treated with 1 wt% KCl. These insights allowed precise adjustments of the electrical and thermal conductivities, leading to an enhancement in the maximum value of figure-of-merit (ZT) from 0.76 to 0.96 through the selective dissolution of KCl approach. We believe that our observations potentially enable advances in thermoelectric materials by engineering microstructures.

This research focuses on enhancing the efficiency of Bi2Te3-based thermoelectric generators (TEGs) in ocean thermal energy conversion (OTEC) systems through innovative heat exchanger designs. Our comparative study uses computer simulations to evaluate three types of heat exchangers: cavity, plate-fins, and longitudinal vortex generators (LVGs). We analyze their impact on thermoelectric conversion performance, considering the thermal energy transfer from warm surface seawater to TEGs. The results demonstrate that heat exchangers with plate-fins and LVGs significantly outperform the cavity heat exchanger regarding thermal energy transfer efficiency. Specifically, plate-fins increase TEG output power by approximately 22.92% and enhance thermoelectric conversion efficiency by 38.20%. Similarly, LVGs lead to a 13.02% increase in output power and a 16.83% improvement in conversion efficiency. These advancements are contingent upon specific conditions such as seawater flow rates, fin heights, LVG tilt angles, and locations. The study underscores the importance of optimizing heat exchanger designs in OTEC systems, balancing enhanced heat transfer against the required pump power. Our findings contribute to a broader understanding of materials science in sustainable energy technologies. [ABSTRACT FROM AUTHOR]

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Bi2Te3-based materials are promising candidates for near-room-temperature applications due to their high thermoelectric performance and low cost. Here, an innovative thermal diffusion strategy combined with magnetron sputtering and thermal evaporation methods was employed to fabricate Bi2Te3 flexible thin films (f-TFs) on a flexible polyimide substrate. An in situ synthesis of Bi2Te3 f-TFs with good crystallinity was obtained using a straightforward thermal diffusion method through diffusion of Te into a Bi precursor under low vacuum conditions (1 × 105 Pa). This method offers easy preparation, low cost, and a large-area film preparation for industrialization. The electrical conductivity increases with increasing thermal diffusion temperatures. A high room temperature carrier mobility of ~28.7 cm−2 V−1 S−1 and an electrical conductivity of ~995.6 S cm−1 can be achieved. Then, a moderate room temperature Seebeck coefficient >100 μV K−1 was obtained due to the chemical stoichiometry being close to the standard by optimizing the thermal diffusion temperature. Consequently, a maximum room temperature PF of ~11.6 μW cm−1 K−1 was observed in Bi2Te3 f-TFs prepared using a thermal diffusion temperature of 653 K. The thermal diffusion strategy applied in the thin film preparation represents an effective approach for the preparation of high thermoelectric performance Bi2Te3 f-TFs, offering a promising route for future thermoelectric applications. [ABSTRACT FROM AUTHOR]

The electrical resistivity and the Hall effect of topological insulator Bi2Te3 and Bi2Se3 single crystals were studied in the temperature range from 4.2 to 300 K and in magnetic fields up to 10 T. Theoretical calculations of the electronic structure of these compounds were carried out in density functional approach, taking into account spin–orbit coupling and crystal structure data for temperatures of 5, 50 and 300 K. A clear correlation was found between the density of electronic states at the Fermi level and the current carrier concentration. In the case of Bi2Te3, the density of states at the Fermi level and the current carrier concentration increase with increasing temperature, from 0.296 states eV−1 cell−1 (5 K) to 0.307 states eV−1 cell−1 (300 K) and from 0.9 × 1019 cm−3 (5 K) to 2.6 × 1019 cm−3 (300 K), respectively. On the contrary, in the case of Bi2Se3, the density of states decreases with increasing temperature, from 0.201 states eV−1 cell−1 (5 K) to 0.198 states eV−1 cell−1 (300 K), and, as a consequence, the charge carrier concentration also decreases from 2.94 × 1019 cm−3 (5 K) to 2.81 × 1019 cm−3 (300 K). [ABSTRACT FROM AUTHOR]

Commercial Peltier cooling devices and thermoelectric generators mostly use bismuth telluride-based materials, specifically its alloys with Sb2Te3 for the p-type legs and its alloys with Bi2Se3 for the n-type legs. If the p-type materials perform with zT well above the unity around room temperature, the n-type counterpart is lacking efficiency in this temperature range, and has the disadvantage of containing selenium. Indeed, despite the fact that selenium is not environmentally benign and that its handling requires precautions, the use of selenium does not facilitate the optimization of thermoelectric performance at or around room temperature, as the presence of selenium results in a larger band gap. In this study, we investigate the feasibility of a selenium-free n-type (Bi, Sb)2Te3 using a simple two-step process: mechanical alloying synthesis followed by spark plasma sintering. All the members of the solid solution Bi2−xSbxTe3 with x < 1 are n-type materials, with zTs between 0.35 and 0.6. The zT is maximized at lower temperatures with an increasing Sb content, which is proof that the band gap is reduced accordingly. We also show here that an edge-free sintering process considerably improves thermoelectric performance. [ABSTRACT FROM AUTHOR]

Bi2Te3-based materials were prepared by direct ink writing (DIW) 3D printing and their microstructure and thermoelectric properties were investigated with an emphasis on the effect of the content of DMF and Te/Se addition. As the mass ratio of DMF in the composition increased from 6.5% to 8.0% (in mass), the electrical conductivity deteriorated because of the corresponding increased porosity and organic remains in the samples. However, the volatilization of DMF would reduce the fluidity of the slurry. Thus, thermoelectric slurry with 7.0% DMF is the most suitable mass ratio for 3D printing. Additionally, adding Te in the p-type Bi0.4Sb1.6Te3 and adding Se in the n-type Bi2Te2.6Se0.4 have significantly improved their electrical conductivity due to the increased carrier concentration and mobility. Combining with the moderate Seebeck coefficient (∼200 μV/K), high power factors with ∼802 μW·m−1·K−2 and 1266 μW·m−1·K−2 were obtained for the n-type Bi2Te2.6Se0.4+10%Se and p-type Bi0.4Sb1.6Te3+7%Te, respectively, which result in the final relatively high zT values of 0.68 at 573 K and 0.56 at 330 K for n-type and p-type 3D-printed samples.

Conventional thermoelectric generators, predominantly based on the π-type structure, are severely limited in their applications due to the relatively low conversion efficiency. In response to the challenge, in this work, a Bi2Te3-based thermoelectric transistor driven by laser illumination is demonstrated. Under laser illumination, a temperature difference of 46.7 °C is produced between the two ends of the transistor structure. Further, the hole concentrations in each region redistribute and the built-in voltages decrease due to the temperature difference, leading to the formation of the transistor circuit. Additionally, the operation condition of the thermoelectric transistor is presented. The calculation results demonstrate that the maximum output power of such a designed thermoelectric transistor is 0.7093 μW. [ABSTRACT FROM AUTHOR]

It has been highly demanded to optimize the charge carrier concentration in 2D Bi2Te3 to achieve enhanced thermoelectric performance. This work reveals that, constructing 2D Bi2Te3/Si heterostructure with tuned interfacial electronic band structure can meet the above needs. When the work function in Si substrate is decreased from 4.6 to 4.06 eV, the charge carrier concentration and electron effective mass are increased simultaneously. Consequently, the electrical conductivity of 2D Bi2Te3 on n++-Si has reaches up to 1250 S·cm−1, which is 90% higher than the counterpart on SiO2/Si substrate, although the Seebeck coefficient in these two samples is around −103 μ V·K−1. The resultant power factor of 2D Bi2Te3/n++-Si heterostructure is 13.4 μ W·cm−1·K−2, which is one of the best values among similar studies ever reported. This work demonstrates a facile way to improve thermoelectric properties via interfacial engineering in a heterostructure. [ABSTRACT FROM AUTHOR]

Reducing the thermal conductivity of thermoelectric materials has been a field of intense research to improve the efficiency of thermoelectric devices. One approach is to create a nanostructured thermoelectric material that has a low thermal conductivity due to its high number of grain boundaries or voids, which scatter phonons. Here, we present a new method based on spark ablation nanoparticle generation to create nanostructured thermoelectric materials, demonstrated using Bi2Te3. The lowest achieved thermal conductivity was <0.1 W m − 1 K − 1 at room temperature with a mean nanoparticle size of 8 ± 2 nm and a porosity of 44%. This is comparable to the best published nanostructured Bi2Te3 films. Oxidation is also shown to be a major issue for nanoporous materials such as the one here, illustrating the importance of immediate, air-tight packaging of such materials after synthesis and deposition. [ABSTRACT FROM AUTHOR]

Wearable thermoelectric generators (w-TEGs) convert thermal energy into electrical energy to realize self-powering of intelligent electronic devices, thus reducing the burden of battery replacement and charging, and improving the usage time and efficiency of electronic devices. Through finite element simulation, this study successfully designed high-performance thermoelectric generator and made it into wearable thermoelectric module by adopting "rigid device—flexible connection" method. It was found that higher convective heat transfer coefficient (h) on cold-end leads to larger effective temperature difference (ΔTeff) and better power generation performance of device in typical wearable scenario. Meanwhile, at same h on the cold-end, longer TE leg length leads to larger ΔTeff established at both ends of device, larger device output power (Pout) and open-circuit voltage (Uoc). However, when the h increases to a certain level, optimization effect of increasing TE leg length on device power generation performance will gradually diminish. For devices with fixed temperature difference between two ends, longer TE leg length leads to higher resistance of TEGs, resulting in lower device Pout but slight increase in Uoc. Finally, sixteen 16 × 4 × 2 mm2 TEGs (L = 1.38 mm, W = 0.6 mm) and two modules were fabricated and tested. At hot end temperature Th = 33 °C and cold end temperature Tc = 30 °C, the actual maximum Pout of the TEG was about 0.2 mW, and the actual maximum Pout of the TEG module was about 1.602 mW, which is highly consistent with the simulated value. This work brings great convenience to research and development of wearable thermoelectric modules and provides new, environmentally friendly and efficient power solution for wearable devices. [ABSTRACT FROM AUTHOR]

Lead sulfide colloidal quantum dots (PbS CQDs) are promising optoelectronic materials due to their unique properties, such as tunable band gap and strong absorption, which are of immense interest for application in photodetectors and solar cells. However, the tunable band gap of PbS CQDs would only cover visible short-wave infrared; the ability to detect longer wavelengths, such as mid- and long-wave infrared, is limited because they are restricted by the band gap of the bulk material. In this paper, a novel photodetector based on the synergistic effect of PbS CQDs and bismuth telluride (Bi2Te3) was developed for the detection of a mid-wave infrared band at room temperature. The device demonstrated good performance in the visible-near infrared band (i.e., between 660 and 850 nm) with detectivity of 1.6 × 1010 Jones at room temperature. It also exhibited photoelectric response in the mid-wave infrared band (i.e., between 4.6 and 5.1 μm). The facile fabrication process and excellent performance (with a response of up to 5.1 μm) of the hybrid Bi2Te3/PbS CQDS photodetector are highly attractive for many important applications that require high sensitivity and broadband light detection. [ABSTRACT FROM AUTHOR]

By effectively converting waste heat into electricity, thermoelectric materials and devices can provide an alternative approach to tackle the energy crisis. Amongst thermoelectric materials, bismuth telluride (Bi2Te3) and its derivatives exhibit high figure of merit ZT values in the near-room-temperature region and show great potential for application in thermoelectric devices. Considering the rapid development of Bi2Te3-based thermoelectric materials and their devices in the last few years, a short and systematic review is much needed. Here, we summarize the novel designs, properties, and applications of Bi2Te3-based thermoelectric devices in different contexts, including wearable, portable, implantable, and cross-disciplinary applications. The challenges and outlook for Bi2Te3-based thermoelectric devices are also considered. This work will guide the future development of Bi2Te3-based thermoelectric devices that target broader and more practical applications.

This research focuses on enhancing the efficiency of Bi2Te3-based thermoelectric generators (TEGs) in ocean thermal energy conversion (OTEC) systems through innovative heat exchanger designs. Our comparative study uses computer simulations to evaluate three types of heat exchangers: cavity, plate-fins, and longitudinal vortex generators (LVGs). We analyze their impact on thermoelectric conversion performance, considering the thermal energy transfer from warm surface seawater to TEGs. The results demonstrate that heat exchangers with plate-fins and LVGs significantly outperform the cavity heat exchanger regarding thermal energy transfer efficiency. Specifically, plate-fins increase TEG output power by approximately 22.92% and enhance thermoelectric conversion efficiency by 38.20%. Similarly, LVGs lead to a 13.02% increase in output power and a 16.83% improvement in conversion efficiency. These advancements are contingent upon specific conditions such as seawater flow rates, fin heights, LVG tilt angles, and locations. The study underscores the importance of optimizing heat exchanger designs in OTEC systems, balancing enhanced heat transfer against the required pump power. Our findings contribute to a broader understanding of materials science in sustainable energy technologies.

With growing concerns about the depletion of fossil fuels and climate change, there is an urgent global demand for the development of sustainable and renewable energy sources. The thermoelectric technology, which converts waste heat into electricity, presents a unique opportunity to ensure a sustainable electric supply and enhance energy efficiency without incurring additional costs. Recently, the utilization of three-dimensional (3D) printing technology for fabricating thermoelectric materials has attracted tremendous interest because of the simplicity of design of power generators and the potential for economical manufacturing. This study focuses on research related to Bi _2 Te _3 thermoelectric materials produced using 3D printing, and it highlights the fundamental principles, advantages, challenges, and recent remarkable advancements associated with this manufacturing approach. Furthermore, we explored various device applications, including shape-conformable wearable, and micro devices with printed thermoelectric materials. Finally, we discuss the promising research directions and prospects for industrialization in 3D-printed thermoelectric materials.

Efficient preparation of high-quality topological insulator nanofilms (TINFs) in large scale is demanding. Using a home-built pulsed laser enhanced molecular epitaxy system (PLEES), we efficiently fabricate TINFs with prefect stoichiometry using Bi2Te3 TINFs as an example. Instead of utilizing multiple beam source furnaces to provide essential elements, hybrid targets containing both pure Bi2Te3 and Te targets are applied in a single epitaxial chamber. Moreover, diffraction pattern of growing Bi2Te3 TINFs are monitored in live by a high-energy electron diffractometer, allowing fast optimization of growth conditions. Scanning electron microscopy and atomic force microscopy demonstrate that the surface morphology of the prepared Bi2Te3 nanofilms with a thickness of 70 nm are flat and dense, and energy-dispersive X-ray spectroscopy analysis suggests that the ratio of Bi to Te elements is 2:3. The grazing incidence X-ray diffractometer reveals that the X-ray diffraction peaks of the synthesized nanofilm matches those of the Bi2Te3 standard PDF card. The prepared nanofilm exhibits a weak anti-localization effect at low magnetic fields characterized by physical property measurement system, confirming its unique electrical transporting properties. This work demonstrates that using hybrid targets with optimized growth parameters enable PLEES to efficiently grow high-quality stoichiometric TINFs on a large scale.

The tunable band gap of PbS colloidal quantum dots (CQDs) from ultraviolet (UV) to short-wave infrared (SWIR) bands provides many potential applications in optoelectronics. However, synthesis of large-sized CQDs that exhibit good stability and sensitivity for extended wavelength still remains a technological challenge. In this paper, a novel broadband photodetector based on small size PbS CQDs (with exciton absorption peak at 927 nm) and Bi2Te3 (with wide spectral sensitivity and high absorption) was developed and studied. The device, which comprised of ITO/AZO/PbS CQDs/Bi2Te3/Al, provided an excellent band alignment that facilitated charge dissociation and transmission hence improving the device sensitivity. Furthermore, wavelength extension was also realized through the synergistic effect of these materials, thus demonstrating broadband photodetection with high sensitivity. The heterostructure photodetector demonstrated good performance in the visible and near infrared ranges, especially at a wavelength of 1050 nm exhibiting a high responsivity (R) and detectivity (D*) of 161 A/W and 3.2 × 1013 Jones, respectively. In addition, the device exhibited excellent stability and reversibility after one month of storage without any encapsulation. This work lays a good foundation for the construction of the next generation of highly sensitive broadband CQDs photodetectors.

The increasing demand for electronic devices in the environmental and medical fields has attracted considerable attention regarding their fabrication. As a new type of passive nanoelectronic information device, memristors have been widely used in the fields of information storage, logic operation, and neural networks due to their special electrical properties. However, the selection of new materials, the device fabrication methods, and the improvement of memory performance need further research. In this work, Bi2Te3 memristors were prepared by the hydrothermal synthesis of Bi2Te3 as a resistive dielectric layer material. The properties of the sample were analyzed using SEM, XRD, and XPS characterization methods. The Bi2Te3 memristors were also tested for their performance and stability using an electrochemical workstation, and the results showed that the Bi2Te3 memristors had good performance. Further analysis of the memristive mechanism showed that the resistive mechanism of Bi2Te3 memristors is an interaction of the conducting wire mechanism and the space charge-limited current mechanism. [ABSTRACT FROM AUTHOR]

Mechanically robust thermoelectric materials are essential for designing reliable thermoelectric modules. The Bi2Te3‐based alloys show intrinsically poor mechanical properties, thus improving their mechanical performance is of great significance. In this work, the composites of p‐type Bi0.4Sb1.6Te3 and n‐type Bi2Te2.7Se0.3(CuI)0.003 with different K2Ti6O13 whiskers contents are prepared. Due to the grain refinement and the whiskers strengthening mechanism of crack deflection, whiskers pulling out, and whiskers bridging, the mechanical properties of Bi2Te3‐based materials are significantly improved. In addition, the zT value of the Bi2Te3‐based alloys remains almost unchanged compared with the pristine sample. Our study indicates that whiskers strengthening is an effective route to enhance the mechanical properties of thermoelectric materials. [ABSTRACT FROM AUTHOR]

The investigation, and ultimate application, of topological insulators, typically involve exposure to ambient conditions or their integration with metals, which lead to surface oxidation or material intermixing. X-ray photoelectron spectroscopy (XPS) measurements that demonstrate passivated and intermixing-free interfaces in the topological insulator Bi2Te3 by means of dry-transferred CVD graphene are reported. After air exposure, no traces of Bi2Te3 oxidation are found. Furthermore, it is demonstrated that graphene acts as a very efficient metal and chalcogen diffusion barrier in Bi2Te3/graphene/permalloy (Py) heterostructures, which are relevant for spintronics. Such results are in stark contrast with the significant surface degradation observed in bare Bi2Te3 under ambient conditions and the deep Bi'Te bonding disruption that occurs in Bi2Te3/Py heterostructures. These findings provide a new approach to control and engineer topological insulator interfaces for spintronic applications and a new platform to investigate the combined use of graphene and topological insulator Dirac states. [ABSTRACT FROM AUTHOR]

Thermoelectric Generators (TEGs) are devices that have the ability to directly convert heat into electrical power, or vice-versa, and are being envisaged as one off-the-grid power source. Furthermore, carbon-based materials have been used as a conducting filler to improve several properties in thermoelectric materials. The present work studied the influence on the thermoelectric performance of Bi2Te3 bulk materials by incorporating different concentrations of Multi-Walled Carbon Nanotubes (MWCNT). In order to control and understand the influence of MWCNT dispersion in the nanocomposite, two different production methods (manual grinding and ultrasonication) were carried out and compared. It was verified that a larger dispersion leads to a better outcome for thermoelectric performance. The achieved Seebeck coefficient was up to -162 µV K-1 with a Power Factor of 0.50 µW K-2m-1, for the nanocomposite produced with 11.8 %V of MWCNT. This result demonstrates the ability to increase the thermoelectric performance of Bi2Te3 throughout the addition of MWCNT.

Room-temperature thermoelectric materials provide promising solutions for energy harvesting from the environment, and deliver a maintenance-free power supply for the internet-of-things (IoTs). The currently available Bi2Te3 family discovered in the 1950s, still dominates industrial applications, however, it has serious disadvantages of brittleness and the resource shortage of tellurium (1 × 10−3 ppm in the earth's crust). The novel Mg3Sb2 family has received increasing attention as a promising alternative for room-temperature thermoelectric materials. In this review, the development timeline and fabrication strategies of the Mg3Sb2 family are depicted. Moreover, an insightful comparison between the crystallinity and band structures of Mg3Sb2 and Bi2Te3 is drawn. An outlook is presented to discuss challenges and new paradigms in designing room-temperature thermoelectric materials.

The need of sustainable energy sources drives the development of efficient hydrogen evolution reaction (HER) catalysts, inspiring innovative approaches to boost catalytic performance. Here, we introduce a method harnessing the unique properties of layered bismuthene to enhance the active sites of Bi 2 Te 3. Through comprehensive characterization using XRD, FTIR, SEM, TEM, XPS, and Raman analysis, we elucidate the structural and morphological features of the synthesized material. Electrochemical assessments by employing cyclic voltammetry, linear sweep voltammetry, electrochemical impedance spectroscopy, and chronoamperometry techniques reveal the superior electrocatalytic performance of bismuthene incorporated Bi 2 Te 3 composite, characterized by reduced overpotential (119 mV vs RHE at −10 mA/cm2) and Tafel slope (95.4 mV/dec). These findings underscore the efficacy of a few layered bismuthene in enhancing hydrogen production activity, particularly in alkaline environments, for sustainable water splitting processes. Our work presents findings that contribute to the development of catalysts which are scalable, eco-friendly and promise to revolutionize renewable energy technologies, paving the way for a cleaner and more accessible era of hydrogen fuel. [Display omitted] • Novel approach for enhancing HER activity of Bi 2 Te 3 by incorporating bismuthene. • Proper characterization was performed using XRD, SEM, TEM, XPS, and Raman analysis. • Electrocatalytic performance was performed by CV, LSV, EIS, and chronoamperometry. • Significant reductions in overpotential (119 mV vs RHE at −10 mA/cm2). • The Tafel slope (95.4 mV/dec) confirmed the superior HER performances. [ABSTRACT FROM AUTHOR]

[Display omitted] • Functionally graded thermoelectric materials (FGTEMs) was fabricated via 3D printing. • Sequential 3D printing produced FGTEMs with doping and structure gradients. • FGTEMs was printed at 150 µm resolution with viscoelastic Na-doped Bi 2 Te 2.7 Se 0.3 inks. • Na doping concentration was varied to control the ZT peak temperature. • Output power of the FGTEM module was higher than that of homogeneous material device. Functionally graded materials (FGMs) are heterogeneous, with compositions that vary spatially with respect to their dopant concentrations and structures. FGMs are designed to exhibit the desired properties and functionalities for various target applications. Recently, 3D printing has emerged as a promising method for fabricating FGMs with complex customized geometries and precise distributions of materials. However, the use of 3D printing to fabricate FGMs is generally limited to producing structural materials, and their application to energy and electronic materials remains relatively rare. Thermoelectric power generation is regarded as a unique solution to recover waste heat; however, the strong temperature dependence of suitably efficient materials restricts their widespread application. Herein, we report a sequential 3D printing method for fabricating n-type Bi 2 Te 2.7 Se 0.3 thermoelectric materials with electronic dopant and structural void gradients. The formulation of Na-doped Bi 2 Te 2.7 Se 0.3 particle colloid inks with the desired viscoelasiticity for 3D printing enabled the fabrication of materials with complex architectures and a precision of 150 µm. These materials incorporated atomic doping and macroscopic void gradients. The thermoelectric peak temperatures of the printed materials varied from room temperature to 450 K, depending on the doping concentration. The graded thermoelectric materials were designed to have a wide operable temperature window and was fabricated by 3D printing, thereby enabling the fabricated devices to deliver enhanced power-generating performance compared with that of devices based on the homogeneous material. The proposed method enables rapid and cost-effective production of functionally graded thermoelectric materials with applications in energy and electronic devices. [ABSTRACT FROM AUTHOR]

In this work, we synthesized poly(3,4-ethylenedioxythiophene): poly (styrene sulfonate) (PEDOT: PSS) and PEDOT: PSS/Bi 2 Te 3 hybrid composite film using a spin coating method. The maximum Seebeck coefficient (22 μVK−1) and power factor (57.18 μWm-1 K−2 around 300 K) were achieved at 0.4 wt% Bi 2 Te 3. The electrical conductivity (σ) reached a maximum of 1467 Scm−1 at 300 K for 0.6 wt% Bi 2 Te 3 , which is more than three times higher than that of pure PEDOT: PSS. Two critical components contribute to the improved electrical transport performance, as identified by XRD, Raman spectroscopy, XPS, AFM, and SEM. First, the conductive polymer undergoes a structural transformation from a benzenoid to a quinoid configuration, enhancing conductivity. This transformation is due to the interaction between the π bonds of PEDOT: PSS and the Van der Waals forces between the tellurium (Te) atom layers of Bi 2 Te 3. Second, the interfacial barrier between PEDOT: PSS and Bi 2 Te 3 creates an energy-filtering effect that increases the Seebeck coefficient. Process flow for preparation of PEDOT: PSS/Bi 2 Te 3 composite film by spin coating method. [Display omitted] • Demand for eco-friendly energy from waste heat using thermoelectric materials is rising. • Study examines thermoelectric properties of PEDOT: PSS/Bi 2 Te 3 composite. • Thermoelectric efficiency of PEDOT: PSS is greatly improved by incorporating Bi 2 Te 3 composite films. • PEDOT: PSS/0.4 wt% Bi 2 Te 3 shows the highest Seebeck coefficient and power factor values. • Results highlight PEDOT: PSS's potential in energy harvesting and waste heat recovery. [ABSTRACT FROM AUTHOR]

Bismuth telluride (Bi 2 Te 3) thermoelectric devices play a significant role in recovering low-grade waste heat. While for Bi 2 Te 3 /Cu joints, excessive interfacial reaction and diffusion usually happens, which greatly degrades their properties. In this work, the novel NiMo diffusion barrier plating was prepared on Bi 2 Te 2.7 Se 0.3 (n -BST) surface prior to the soldering process. The joint interfacial microstructure, shear strength, contact resistance and thermal stability were systematically investigated. The maximum shear strength increased from 7 MPa to 12 MPa with the joint contact resistance decreasing from 11.86 μΩ⋅cm2 to 3.27 μΩ⋅cm2 after NiMo plating preparation. These n -BST/Cu joints were then annealed for different durations to investigate the joint thermal stability. After annealing at 110 °C for 250 h, a thin BiTe + NiTe 2 reaction layer formed instead of the initial SnTe reaction layer. The joint shear strength maintained 9 MPa (less than 2 MPa without NiMo plating) and the joint contact resistance was only 12.39 μΩ⋅cm2 (249.89 μΩ⋅cm2 without NiMo plating). This work indicates that NiMo plating is an effective elemental diffusion barrier for n -BST/Cu joints. [ABSTRACT FROM AUTHOR]

The electrical resistivity and the Hall effect of topological insulator Bi2Te3 and Bi2Se3 single crystals were studied in the temperature range from 4.2 to 300 K and in magnetic fields up to 10 T. Theoretical calculations of the electronic structure of these compounds were carried out in density functional approach, taking into account spin–orbit coupling and crystal structure data for temperatures of 5, 50 and 300 K. A clear correlation was found between the density of electronic states at the Fermi level and the current carrier concentration. In the case of Bi2Te3, the density of states at the Fermi level and the current carrier concentration increase with increasing temperature, from 0.296 states eV−1 cell−1 (5 K) to 0.307 states eV−1 cell−1 (300 K) and from 0.9 × 1019 cm−3 (5 K) to 2.6 × 1019 cm−3 (300 K), respectively. On the contrary, in the case of Bi2Se3, the density of states decreases with increasing temperature, from 0.201 states eV−1 cell−1 (5 K) to 0.198 states eV−1 cell−1 (300 K), and, as a consequence, the charge carrier concentration also decreases from 2.94 × 1019 cm−3 (5 K) to 2.81 × 1019 cm−3 (300 K).

Abstract Solution processability and flexibility still remain major challenges for many thermoelectric (TE) materials, including bismuth telluride (Bi2Te3), a typical and commercially available TE material. Here, we report a new solution‐processed method to prepare a flexible film of a Bi2Te3/single‐walled carbon nanotube (SWCNT) hybrid, where the dissolved Bi2Te3 ion precursors are mixed with dispersed SWCNTs in solution and recrystallized on the SWCNT surfaces to form a “cement–rebar”‐like architecture. The hybrid film shows an n‐type characteristic, with a stable Seebeck coefficient of −100.00 ± 1.69 μV K−1 in air. Furthermore, an extremely low in‐plane thermal conductivity of ∼0.33 W m−1 K−1 is achieved at 300 K, and the figure of merit (ZT) reaches 0.47 ± 0.02. In addition, the TE performance is independent of mechanical bending. The unique “cement–rebar”‐like architecture is believed to be responsible for the excellent TE performances and the high flexibility. The results provide a new avenue for the fabrication of solution‐processable and flexible TE hybrid films and will speed up the applications of flexible electronics and energy conversion.

The Sn-Ag-Cu-based solder paste screen-printing method has primarily been used to fabricate Bi2Te3-based thermoelectric (TE) modules, as Sn-based solder alloys have a low melting temperature (approximately 220℃) and good wettability with Cu electrodes. However, this process may result in uneven solder thickness when the printing pressure is not constant. Therefore, we suggested a novel direct-bonding method between the Bi2Te3-based TE elements and the Cu electrode by electroplating a 100 µm Sn/ 1.3 µm Pd/ 3.5 µm Ni bonding layer onto the Bi2Te3-based TE elements. It was determined that there is a problem with the amount of precipitation and composition depending on the pH change, and that the results may vary depending on the composition of Pd. Thus, double plating layers were formed, Ni/Pd, which were widely commercialized. The Sn/Pd/Ni electroplating was highly reliable, resulting in a bonding strength of 8 MPa between the thermoelectric and Cu electrode components, while the Pd and Ni electroplated layer acted as a diffusion barrier between the Sn layer and the Bi2Te3 TE. This process of electroplating Sn/Pd/Ni onto the Bi2Te3 TE elements presents a novel method for the fabrication of TE modules without using the conventional Sn-alloy-paste screen-printing method.

The activation of carbon dioxide (CO2) molecules and separation/transfer of photoinduced charge carriers are two crucial factors influencing the efficiency of CO2 photoreduction. Herein, we report a p-type Bi2Te3/commercial TiO2 (pBT/P25) nanocomposite for enhanced CO2 photoreduction. Upon light irradiation, a temperature gradient formed in pBT induces the Seebeck effect to build a thermoelectric field, which promotes the charge carriers' separation/transfer. Additionally, pBT with a strong light absorption capacity generates the photothermal effect favoring the activation of CO2 molecules. In addition, the excellent electric conductivity and large work function render pBT an efficient cocatalyst for further improving the charge carriers' separation/transfer. Owing to the synergistic enhancement effect of pBT on the activation of CO2 molecules and promotion of charge separation/transfer, we achieved the highest CO evolution rate over pBT(2)/P25 of 19.2 μmol·gcat−1·h−1, which was approximately 5.5 times that of bare P25. This work suggests that a thermoelectric material/semiconductor nanocomposite could be developed as an efficient photo-thermo-electro-chemical conversion system for enhanced CO2 reduction via promoting the charge carriers' separation/transfer. [ABSTRACT FROM AUTHOR]

Bi2Te3 is a classical thermoelectrical material and has been applied widely in commerciality. In this paper, the influence of La2O3 dispersion as the nanosecond phase on the thermoelectric properties of Bi2Te3 was investigated. The Bi2Te3 nanopowders were prepared by the hydrothermal method. After adding the La2O3 nanopowders according to Bi2Te3 + s wt% La2O3 (s = 0 , 0.5, 1.0, 1.5), they were hot pressed into bulks in vacuum. The experimental results showed that the dispersed La2O3 as the nanosecond phase could enhance phonon scattering and suppress the thermal conductivity of Bi2Te3 effectively. Although their electrical resistivity increased due to the deteriorated carrier mobility, as a combined effect, the thermoelectric merit value (ZT) of the Bi2Te3 + 0.5 (or 1.0) wt% La2O3 was optimized and reached 0.61 at about 455 K. [ABSTRACT FROM AUTHOR]

In order to improve the thermoelectric and mechanical properties of p-type Bi2Te3 thermoelectric material, Bi0.5Sb1.5Te3/Ni&Cu core/shell powders were electroless plated with the same content of Ni and different content of Cu, and then reduced by hydrogen, and finally sintered into bulk by spark plasma sintering. After composite electroless plating with Ni&Cu, for the bulk sample with 0.3 wt% Ni and 0.15 wt% Cu, the power factor rises significantly and the highest value increases from 25 to 33 µW·cm−1·K−2 at room temperature. Meanwhile, the thermal conductivity decreases to about 0.80 W·m−1·K−1 at 623 K. Therefore, the composite electroless plating with Ni&Cu can obviously improve the electrical and thermal transport performance of p-type Bi2Te3 based thermoelectric materials. Thus, the ZT value enhances significantly and the highest value increases over 3 times, from 0.35 to 1.16 at 473 K in Bi0.5Sb1.5Te3 with 0.3 wt% Ni and 0.15 wt% Cu bulk sample. At the same time, the mechanical properties have also been improved after composite electroless plating with Ni&Cu. [ABSTRACT FROM AUTHOR]

Bi 2 Te 3 is a successful and commercial thermoelectric material. However, Bi 2 Te 3 is easily generates point defects, which limits its thermoelectric (TE) properties. This study presents a novel method to tune point defects by using short-range atomic diffusion via pulsed electric field (PEF) treatment in C-doped Bi 2 Te 3 films. The C atoms migrate from the interstitial position in the Bi layer (C i) and the Van der Waals gap (C vdw) to the Bi vacancy after the PEF treatment. For this case, it increases the content of the Te–C bonds for the PEF films, resulting in increased electron concentration. And the PEF can eliminate amorphous regions of the C-doped Bi 2 Te 3 films. In addition, the shorter bond length of the Te–C improves the compressive stress of the film and increases the effective mass of carriers. Thus, the conductivity and the Seebeck coefficient are improved simultaneously. In this study, the power factor was 2450.32 μW m−1·K−2 at 513 K after the PEF treatment. Therefore, the PEF is an effective method to improve TE properties by short-range atomic diffusion. [ABSTRACT FROM AUTHOR]