Thermoelectric Research Articles

Self-sensing function and thermoelectric effect of engineered cementitious composites (ECC) with porous structures

This study investigates the self-sensing and thermoelectric mechanism of ultra-lightweight engineered cementitious composites (ULW-ECC) with porous structures by comparing seven different mixtures. Porous structures based on fly ash cenosphere (FAC) and polyethylene (PE) fibre are compared with those formed solely by individual materials (air-entraining admixture (AEA), FAC, PE fibre), as well as dense structure (pure cement). Mechanical properties, electrical conductivity, thermal conductivity, and self-sensing capabilities (compression, bending, and tension) were systematically tested. Additionally, thermoelectric behaviours were examined under various treatment methods (normal state and leaching treatment) and electrodes. Scanning electronic microscope (SEM) and mercury intrusion porosimeter (MIP) analysis were conducted to explain the self-sensing and thermoelectric mechanism of ULW-ECC. Results indicate that achieving self-sensing functionality in cementitious composites without conductive fillers and other special treatments is feasible through the creation of a porous structure, with enhanced performance corrected with increased porosity. Such porous structure can be achieved using high-volume FAC, PE fibres, and AEA either independently or in combination. Furthermore, cement-based composites exhibit ionic thermoelectric performance, with efficiency influenced by mineral admixtures, porosity, specific porous area, electrode types, and leaching treatment. The ionic Seebeck coefficient increases with higher porosity and specific surface area, resulting in ULW-ECC with a porous structure demonstrating a superior ionic Seebeck coefficient compared to pure cement. This study provides novel insights into the versatile applications of ULW-ECC and other cement-based composites.

Multiple defect states engineering towards high thermoelectric performance in GeTe-based materials

GeTe is a promising material for thermoelectric (TE) applications. However, its low Seebeck coefficient and high thermal conductivity in the mid-temperature range of 298–550 K have hindered its widespread use in TE devices. In this work, we show that a combination of band engineering, Fermi level tuning, and miscibility gap exploration can significantly improve the energy conversion performance of GeTe. Bi provides the optimized carrier concentration and induces band convergence, while Ga possibly forms a resonant state. The synergistic effects of Bi and Ga significantly improve the Seebeck coefficient from 38 µVK−1 for undoped GeTe to over 120 µVK−1 for Bi and Ga-containing materials at 298 K and provide a high power factor over a wide temperature range. Phonon scattering is strengthened by optimizing the microstructure through Pb-induced spinodal decomposition and enhanced point defect scattering due to increased dopant solubility, resulting in a very low lattice thermal conductivity of about 0.5 Wm-1K−1 at 600 K for the triple-doped samples. The maximum thermoelectric figure of merit ZT was significantly increased to 2.1 at 600 K for the Ge0.87Pb0.05Bi0.06Ga0.02Te sample due to the improved power factor and reduced lattice thermal conductivity. Additionally, the average figure of merit ZTave for this sample achieved a very high value of 1.4 for Ge0.87Pb0.05Bi0.06Ga0.02Te at a temperature gradient of 475 K (Tc = 298 K). The developed material shows great potential for use in energy conversion devices, with an estimated energy conversion efficiency exceeding 17 %.

The structure, magnetic properties, magnetotransport and temperature coefficient of resistivity of hexagonal 4H-SrMnO3 manganite

The perovskite hexagonal SrMnO3 manganite with four layers (4H-SrMnO3) have been one of the hot topics in materials science due to the physical characteristics of antiferromagnetic, ferroelectric, and thermoelectric effects. The transport properties and magnetoresistance (MR) effect of 4H-SrMnO3 have seldom been reported. The structure, temperature coefficient of resistivity (TCR), magnetic and magnetotransport properties of the 4H-SrMnO3 SrMnO3 manganite obtained by solid state reaction have been investigated in this work. X-ray diffraction (XRD), scanning electron microscopy (SEM) and energy dispersive spectroscopy (EDS) measurements at room temperature reveal that the SrMnO3 sample exhibits a pure hexagonal symmetric structure, with uniform distribution of particles and elements. Under applied magnetic fields of 2000 Oe, the SrMnO3 sample exhibits a transition from antiferromagnetic (AFM) to paramagnetic (PM) behavior at approximately 280 K, known as the Néel temperature (TN). The resistance is influenced by the magnetic field, but overall exhibits an insulating state. Remarkably, the SrMnO3 sample shows significant MR effect near room temperature. The negative MR near room temperature varies from 5.8 % with 1 T field to 16.8 % with 6 T field, indicating an existence of obvious MR in the hexagonal AFM SrMnO3 manganite. Furthermore, the maxmium value of TCR reaches 4.34 % K−1 near room temperature. These findings of room-temperature TCR and room-temperature MR in the AFM 4H-SrMnO3 hold immense value for the research and potential application of the AFM spintronics and devices.

Computational advances for energy conversion: Unleashing the potential of thermoelectric materials

Thermoelectric (TE) materials have lately attracted a lot of attention and sparked a flurry of research because of their potential for energy conversion and broad spectrum of applications, including waste heat recovery, thermocouples, sensors, and refrigeration. Additionally, they could potentially be able to offer extremely effective and eco-friendly methods for energy production and harvesting, which might aid in addressing the world's energy concerns. Concerning the advancement in condensed matter physics, although a plethora of research has been devoted to identifying suitable TE materials over the years, there is still scope for the exploration of new materials. This review article strives to project extensive progress in the field of thermoelectricity, commencing with a discussion on various classes of TE materials scrutinized based on TE coefficients such as thermopower, power factor, and thermal conductivity computed within the framework of DFT, combined with an in-depth look at the computational techniques used. A wide range of prospective TE material classes, including chalcogenides, pnictides, oxides, perovskites, transition metal dichalcogenides (TMD), and a few more, are meticulously addressed, stressing the unique characteristics of each class in separate sections and subsections. SrAgChF (Ch = S, Se, Te), with its superlattice structure, boasts high thermopower for both carriers, making it ideal for power generation. Similarly, ThOCh (Ch = S, Se, Te) and NbX2Y2 (X = S, Se, Y = Cl, Br, I) chalcogen materials exhibit significant thermoelectric properties in both bulk and monolayer forms. Fe2GeCh4 (Ch = S, Se, Te) demonstrates exceptional anisotropic TE characteristics, advantageous for device applications. Structurally resembling chalcopyrites, Zn-based pnictides show high efficiency, validated by the analysis of power factor scaled by temperature and relaxation time (S2σT/τ: where S is thermopower, σ is electrical conductivity, S2σ is power factor, T is temperature and τ is the relaxation time). Moreover, CaLiPn (Pn = As, Sb, Bi) emerges as more favorable for TE applications than SrLiAs, displaying low lattice thermal conductivity. Among transition metal dichalcogenides (TMDs), OsX2 (S, Se, Te) exhibits high thermopower, while FeS2 displays remarkable thermoelectric properties in both marcasite and pyrite structural phases. In exploring 2D materials akin to graphene, ReS2's TE properties have been scrutinized across various forms, showcasing significant potential, especially when tailored for flexibility. Compounds like CaSrX (X = Si, Ge, Sn, Pb) and ZnGeSb2 exhibit notable TE features, indicating avenues for strain-engineered modulation of TE properties. Lattice dynamics play a pivotal role in TE efficiency, driving investigations into phonon dispersion and thermal properties across materials. CsAgO's remarkably low lattice thermal conductivity highlights its promise as a TE material. Despite the effectiveness of semiclassical approximations, accurately predicting transport parameters requires accounting for scattering effects. Incorporating such factors is essential for precise estimation of the thermoelectric figure of merit (ZT). Notably, CsAgO's low lattice thermal conductivity contributes to its effectiveness, boasting a ZT exceeding 1.4. Layered compounds like CuTlX (X = S, Se) exhibit extreme anisotropy in lattice thermal conductivity and achieve ZT values surpassing one at 300 K. LaAgXO (X = Se, Te) shows a high ZT exceeding 2.5, particularly under heavy carrier doping. The best aspects of the compounds studied, the future of TE materials in the context of device application, the development of flexible and wearable TE materials, and strategies for improving TE parameters are all discussed in this review's conclusion.

Experimental detection of mechanical deformations exploiting electromechanical effects

The present paper discusses experimental results concerning the deformation-induced generation of electric potential difference in steel specimens. According to our observations, voltages in the order of 10 microVolts can be measured between points on the surfaces of steel bodies during mechanical deformation. Three different experimental set-ups were used to determine the properties of the phenomenon, carefully excluding the influence of possible external electromagnetic fields. In order to exclude thermoelectric effects, a special steel specimen was fabricated. Further experimental campaigns were conducted with long, thin metallic rods in two different set-ups: the generation of voltage was measured during the traveling of longitudinal shock waves and during bending vibrations of the specimens. The results indicate that the variation of the magnetization of the material – the magnetoelastic effect – plays an important role in the phenomenon, but thermoelectricity also contributes to the measurable voltage signals. The electromechanical effect identified in the present paper may have several applications in measurement technology. The most relevant advantage of the applied measurement methods is that these are essentially sensor-free, since the mechanical vibrations can be detected by simply soldering, welding, or pressing copper wires to the examined steel specimen.

Thermoelectric devices with polymer/zeolite hybrid composite films for conversion of heat to electricity

Here we report that organic/inorganic hybrid composite films, consisting of poly(3,4-ethylenedioxythiophene):poly(styrene sulfonate) (PEDOT:PSS) and zeolite Y (Zy), can efficiently convert heat to electricity in the horizontal device geometry. The PEDOT:PSS/Zy (PPZy) hybrid composite films were prepared from corresponding aqueous solutions at various Zy contents (up to 50 wt%). The PPZy solutions exhibited an increased viscous state with a maximum at Zy = 30 wt%, indicating strong interactions between PEDOT:PSS and Zy components. All devices with the PPZy composite films could convert heat to electricity and showed higher thermoelectric (TE) performances than those with the pristine PEDOT:PSS films. The TE devices with the PPZy films (Zy = 30 wt%) delivered an output power of 8.8 pW with a power factor of 0.76 μW/mK2, which is ca. 20 times higher than those with the pristine PEDOT:PSS films. The flexible TE devices, which were fabricated on poly(ethylene naphthalate) (PEN) film substrates, exhibited robust TE performances even after 5000 bending cycles. The present approach of hybrid composite films based on zeolite particles may contribute to further TE performance improvement for flexible and wearable TE devices.

Stabilizing Distorted Ductile Semiconductors for Excellent Ductility and Thermoelectric Performance

AbstractElement doping/alloying is a common strategy to tune the electrical and thermal transports of thermoelectric (TE) materials, but the doping/alloying limit of foreign elements in many TE materials is usually very low, bringing a great challenge to improve the TE performance. In this work, beyond the classic principle of “like dissolves like,” it is found that choosing the compound with a severely distorted lattice and diversified chemical bonding as the matrix also facilitates achieving a high doping/alloying limit. Taking ductile semiconductors as an example, this work shows that gold (Au) element is nearly immiscible in Ag2S and Ag2Te, but has a relatively high alloying limit in complex Ag2S0.5Te0.5 meta‐phase. Au in Ag2S0.5Te0.5 significantly decreases the carrier concentration and improves the TE performance, but scarcely changes the mechanical properties. Consequently, Ag1.99Au0.01S0.5Te0.5 demonstrates both a high figure‐or‐merit of 0.95 at 550 K and extraordinary room‐temperature ductility. This work offers an effective and general strategy to develop stabilized doped/alloyed TE materials.

Synergistic effects of hybrid n-doping on the thermoelectric performance and air-stability of water-processable single-walled carbon nanotubes

Organic thermoelectrics (TEs) based on carbon nanotubes (CNTs) have attracted much attention with their inherent advantages, such as, earth-abundant elements, broad electronic tunability, and excellent mechanical compliance. However, the inferior TE performance and doping stability of n-type CNTs to those of p-type CNTs have been bottlenecks to establish CNT-based next-generation TEs. Herein, we report a hybrid n-doping method that improves the n-type TE performance and long-term air-stability of water-processable single-walled CNT (SWCNT) and carboxymethyl cellulose (CMC) composite. The hybrid n-doping process with polyethyleneimine (PEI) n-dopant contains primary addition and secondary immersion doping, which causes a simultaneous increase in electrical conductivity and Seebeck coefficient through efficient n-doping and surface energy filtering effect, respectively. Furthermore, the hybrid-doped films exhibit superior long-term stability by inhibiting the oxidation of SWCNT/CMC at nanoscale, which allows to ensure the initial power factor even after storing in ambient for a month. Finally, we successfully demonstrated hybrid-doped SWCNT/CMC-based TEGs with long-term stable output characteristics. This work can offer insights to develop efficient and air-stable n-type organic TE materials and devices.

A Highly Robust, Multifunctional, and Breathable Bicomponent Fibers Thermoelectric Fabric for Dual-Mode Sensing.

Wearable thermoelectric (TE) materials are seen as excellent candidates for flexible electronics because of their unique self-powered properties, multistimulus sensing and human waste heat conversion. However, currently reported flexible TE materials still face challenges such as poor durability, uncomfortable wearing and sensing signals crosstalking each other. Herein, this study describes a hot-air cross-linking method for the preparation of multifunctional TE fabrics with enhanced durability. Poly(ethylene terephthalate) (PET) fibers with core and sheath structures having different melting points were selected as flexible substrates. Poly(3,4-ethylenedioxythiophene)-poly(styrenesulfonate) (PEDOT:PSS) and single-walled carbon nanotubes (SWCNTs) were embedded stably on the surface of the sheath layer in the presence of heat treatment. The fiber-welded structure created by thermal cross-linking improves the durability of TE fabrics, including consistent mechanical and electrical properties after a 6 h wash test and 6000 compression cycles. The unique fiber structure of TE fabrics ensures excellent breathability (313.7 mm s-1 at 200 Pa), which meets the breathability requirements for human wear. In addition, the fiber-prepared sensors have excellent compressive strain response (20 ms response time and 30 ms recovery time) and precise temperature discrimination (0.17 K minimum discrimination temperature) for accurate real-time monitoring of the sensed signals. Thus, the TE fabrics can be used for human motion recognition, including pulse monitoring, sign language expression, and motions in joint areas. Moreover, the fabricated wearable TE device is connected to a Bluetooth module for wireless transmission, which can be used for mechanical and temperature sensing of the robot arm without signals crosstalking. This new durable TE fabric paves the way for the next generation of smart wearable technology.

Wearable Device with High Thermoelectric Performance and Long-Lasting Usability Based on Gel-Thermocells for Body Heat Harvesting.

Utilizing the thermogalvanic effect, flexible thermoelectric materials present a compelling avenue for converting heat into electricity, especially in the context of wearable electronics. However, prolonged usage is hampered by the limitation imposed on the thermoelectric device's operational time due to the evaporation of moisture. Deep eutectic solvents (DESs) offer a promising solution for low-moisture gel fabrication. In this study, a bacterial cellulose (BC)/polyacrylic acid (PAA)/guanidinium chloride (GdmCl) gel is synthesized by incorporating BC into the DES. High-performance n-type and p-type thermocells (TECs) are developed by introducing Fe(ClO4)2/3 and K3/4Fe(CN)6, respectively. BC enhances the mechanical properties through the construction of an interpenetrating network structure. The coordination of carboxyl groups on PAA with Fe3+ and the crystallization induced by Gdm+ with [Fe(CN)6]4- remarkably improve the thermoelectric performance, achieving a Seebeck coefficient (S) of 2.4mVK-1 and ion conductivity (σ) of 1.4 Sm-1 for the n-type TEC, and ‒2.8mVK-1 and 1.9 Sm-1 for the p-type TEC. A flexible wearable thermoelectric device is fabricated with a S of 82mVK-1 and it maintains a stable output over one month. This research broadens the application scope of DESs in the thermoelectric field and offers promising strategies for long-lasting wearable energy solutions.

Enhanced thermoelectric properties of Ag2Se by manipulation in carrier concentration via acetylene carbon black nanocomposites

Pristine Ag2Se has inherent limitations in its Seebeck coefficient and electronic thermal conductivity, necessitating improvements through carrier concentration manipulation. While its porous structure has been utilized to reduce carrier concentrations, achieving optimal values remains challenging. This study explores enhancing Ag2Se with acetylene carbon black (ACB) nanocomposites to further reduce carrier concentrations and improve thermoelectric (TE) properties. ACB, a cost-effective alternative to other carbon materials, has demonstrated potential in enhancing TE performance in various composites. Ag2Se and ACB composites were synthesized by dispersing different ACB weights in a solution, followed by sintering. Characterization using x-ray diffraction (XRD), Transmission and scanning electron microscopy (TEM and SEM), and other techniques confirmed the phase, structure, and morphology of the composites. The addition of ACB resulted in decreased electrical conductivity and increased Seebeck coefficient in Ag2Se, particularly at ACB concentrations up to 5.0 wt%, balancing the power factor (PF). The total thermal conductivity decreased due to mainly reduced electronic thermal conductivity. The 5.0 wt% ACB sample achieved a zT of approximately 0.8 at 383 K, comparable to the performance of composites using more expensive low-dimensional carbon materials.

Insight on thermodynamic and thermoelectric properties of Ge based perovskites AGeO3 (A = Mg, Cd) for energy harvesting applications: A DFT approach

In this manuscript, transport properties like thermoelectric and thermodynamic properties of AGeO3 (A = Mg, Cd) perovskites have been performed in detail along with effect of chemical potential on various thermoelectric parameters. Furthermore, we present the electronic effects and thermodynamic stability of these materials. The MgGeO3 and CdGeO3 alloys have a gap of 3.368 and 2.555 eV, respectively, making them indirect band gap semiconductors. Furthermore, using a constant relaxation time approximation and semiclassical Boltzmann theory, the thermoelectric (TE) properties of both materials have been studied. The lattice thermal conductivity magnitudes for MGeO3 and CdGeO3 are 7.47 W/mK and 21.55 W/mK, respectively, at 300 K. Power Factor (PF) has been measured at approximately 0 chemical potential, or approximately 14 (1011 W/K2 ms) at 1200 K, 7.5 (1011 W/K2 ms) at 700 K, and 3.5 (1011 W/K2 ms) at 300 K for both MgGeO3 and CdGeO3. At room temperature, the electrical conductivities of MgGeO3 and CdGeO3 were measured to be 1.43 × 1015W/mK and 1.08 × 1015W/mK, respectively. Over a broad temperature range (0–1200 K), the thermodynamic parameters, such as heat capacity, entropy, thermal expansion, and Debye temperature, were also computed and discussed.

Analytical study of the thermoelectric properties in silicene

Theoretically, we investigate the thermoelectric (TE) properties namely, electrical conductivity (σ), diffusion thermopower (S d), power factor (PF), electronic thermal conductivity (κ e) and thermoelectric figure of merit (ZT) for silicene on Al2O3 substrate. TE coefficients are obtained by solving the Boltzmann transport equation taking account of the electron scattering by all the relevant scattering mechanisms in silicene, namely charged impurity (CI), short-range disorder (SD), intra- and inter-valley acoustic (APs) and optical (OPs) phonons, and surface optical phonons (SOPs). The TE properties are numerically studied as a function of temperature T (2–400K) and electron concentration n s(0.1–10 × 1012 cm−2). The calculated σ and S dare found to be governed by CIs at low temperatures (T< ∼ 10 K), similar to that in graphene. At higher T, they are found to be mainly dominated by the intra- and inter-valley APs. The resultant σ (S d) is found to decrease (increase) with increasing T, whereas PF remains nearly constant for T> ∼ 100 K. On the other hand, n s dependence shows that σ (S d) increases (decreases) with increasing n s; with PF relatively constant at lower n s and then decreases with increasing n s. At room temperature, the calculated σ (S d) in silicene is closer to that in graphene and about an order of magnitude greater (less) than that in monolayer (ML) MoS2. The κ e is found to be weakly depending on T and Wiedemann–Franz law is shown to be violated. We have predicted a maximum PF ∼3.5 mW m−1 K−2, at 300 K for n s = 0.1 × 1012 cm−2 from which the estimated ZT = 0.11, taking a theoretically predicted lattice thermal conductivity κ l = 9.4 Wm−1 K−1, is a maximum. This ZT is much greater than that of graphene and ML MoS2. The ZT is found to decrease with the increasing n s. The ZT values for other values of n s in silicene, at 300 K, also show much superiority over graphene, thus making silicene a preferred thermoelectric material because of its relatively large σ and very small κ l.

Controlled Phonon Transport via Chemical Bond Stretching and Defect Engineering: The Case Study of Filled β-Mn-Type Phases.

Controlling the elastic properties of the material could become a powerful tool for tuning the thermal transport in solids. Nevertheless, the impact of the crystal structure, chemical bonding, and elastic properties on the lattice thermal conductivity remains to be elucidated. This is a pivotal issue for the advancement of thermoelectric (TE) materials. In this context, the influence of cation substitution in tetrahedral voids on the structural, thermal, and TE properties of α- and β-PbyGa6-xInxTe10─filled β-Mn-type phases─is reported here. The investigated materials show semiconducting behavior and a change from p- to n-type conductivity, depending on the chemical composition and temperature. Our findings indicate that the electronic transport in β-Mn-type phases is largely influenced by the substantial distortion of the Te framework, which causes the low weighted mobility and strong scattering of charge carriers. The presence of a significant anharmonicity of lattice vibrations results in the ultralow lattice thermal conductivity of PbyGa6-xInxTe10 materials. With increasing x, κL decreases from 0.59 to an extremely low value of 0.36 W m-1 K-1 at 298 K due to the decrease of bonding energy, intensification of anharmonic thermal vibrations of atoms, and formation of point defects. This work demonstrates the efficacy of utilizing the crystal structure and elastic properties to regulate phonon transport in functional materials.

Enhanced High-Temperature Thermoelectric Performance in Te-Doped Electronegative Element-Filled Skutterudites via Suppressing Bipolar Effects and Enhanced Phonon Scattering.

CoSb3-based skutterudites have great potential as midtemperature thermoelectric (TE) materials due to their low cost and excellent electrical and mechanical properties. Their application, however, is limited by the high thermal conductivity and the degradation of TE performance at elevated temperatures, attributed to the adverse effects of bipolar diffusion. Herein, a series of SeyCo4Sb12-xTex compounds were successfully synthesized by combining a solid-state reaction and spark plasma sintering techniques to mitigate these challenges. It was found that doping Te at the Sb sites effectively enhanced the carrier concentration and suppressed the bipolar effect to obtain a superior power factor of ∼43 μW cm-1 K-2. Furthermore, due to the low resonant frequency of Se, filling voids of CoSb3 with Se achieved a low lattice thermal conductivity of 1.55 W m-1 K-1. Nevertheless, Se filling introduced additional holes, reducing the carrier concentration without a significant detriment of the carrier mobility. As a result, a maximum figure of merit of 1.23 was achieved for Se0.1Co4Sb11.55Te0.45 at 773 K. This work provides a valuable guidance for selecting appropriate filling and doping components to achieve synergistic optimization of the acoustics and electronics of CoSb3-based skutterudites.

A first principles based exploration of Rb2XHgCl6 (X= Al, Y) halide double perovskites for their applications in futuristic efficient technologies

Herein, the first principles calculations are performed to explore the physical features of Rb2XHgCl6 (X = Al, Y) to unravel their potential candidacy for optoelectronic and thermoelectric applications. The geometry optimization reveals that Rb2XHgCl6 (X = Al, Y) are stable in cubic structure with ferromagnetic nature. Analysis of tolerance factor and formation energies uncovered the thermodynamically stability. Moreover, the semiconductor nature of considered compounds is confirmed by spin dependent electronic characteristics. Rb2XHgCl6 (X = Al, Y) revealed maximum absorption of ultraviolet light which prove that corresponding materials are appropriate for optoelectronic devices. Using BoltzTraP package, the thermoelectric (TE) characteristics are computed within range of 100–800 K. Results suggest that the resultant material are appropriate candidates for spintronic, optoelectronic and TE applications and more stimulate experimentalist to discover these materials for their usage in practical extent.

Tailoring the Thermoelectric Properties of 3D-Printed n-Type Bi1.7Sb0.3Te3 with Incorporated Edge-Oxidized Graphene.

Using three-dimensional (3D) printing technology to fabricate Bi2Te3-based thermoelectric (TE) generators opens a potential way to create shape-conformable devices capable of recovering waste heat from thermal energy sources with diverse surface morphologies. However, pores formed in 3D-printed Bi2Te3-based materials by the removal of the organic ink binder result in unsatisfactory performance compared to the bulk materials, which has limited the widespread application of the ink-based 3D printing process. Furthermore, managing the volatile Se element in the n-type materials poses significant technological challenges compared to the p-type counterparts, resulting in a scarcity of research on 3D printing of n-type Bi2Te3. Here, we synthesized edge-oxidized graphene (EOG)-incorporated Se-free n-type Bi1.7Sb0.3Te3 (BST) using a direct ink writing (DIW) process with a binder-free novel ink. The incorporated EOG provides connectivity between small BST grains separated by pores and induces a bimodal-like grain structure during the DIW and sintering process. The optimal EOG content of 0.1 wt % in 3D-printed n-type BST simultaneously achieved both carrier transport control and active phonon scattering, due to its unique microstructure. A maximum ZT of 0.71 was obtained in the 0.1 wt % EOG/BST materials at 448 K, comparable to commercial bulk n-type Bi2Te3-based materials. Further, a single-element device composed of the EOG-BST material exhibited a 2-fold improvement in performance compared to pure-BST. These results open a technological route for the application of 3D printing technology for ink-based TE materials.

Giant thermoelectric effect governed by unique two-dimensional electronic structure and strong anharmonicity in layered nitrides

Giant thermoelectric effect governed by unique two-dimensional electronic structure and strong anharmonicity in layered nitrides

Bi-functional flexible Ag2Se/Polyvinylidene fluoride composite films for thermal energy conversion and electromagnetic interference shielding by solution 3D printing

Developing bi-functional thermoelectric (TE) and electromagnetic interference (EMI) shielding materials is an effective way for the integrated electronic devices to face the accumulated thermal energy and complicated electromagnetic environment. Herein, flexible Ag2Se/polyvinylidene fluoride (Ag2Se/PVDF) composite films were successfully prepared through solution 3D printing and subsequent annealing treatment. As Ag2Se content increased, both the power factor and average total EMI shielding effectiveness (SET) were boosted. When the mass fraction of Ag2Se was 85 wt%, a power factor of 904.6 μW m−1K−2 at 360 K was achieved for the ASP-85 composite film. Meanwhile, this ASP-85 composite film shown the outstanding SET value of 56.1 dB at 52 μm thickness. Flexible Ag2Se/PVDF composite films displayed the excellent thermal energy conversion and EMI shielding capacity.

Study of Characteristics of Thermoelectric Effect in Energy Conversing Materials at Nanoscale

Study of Characteristics of Thermoelectric Effect in Energy Conversing Materials at Nanoscale