Thermoelectric Research Articles

The Latest Advances in Ink-Based Nanogenerators: From Materials to Applications.

Nanogenerators possess the capability to harvest faint energy from the environment. Among them, thermoelectric (TE), triboelectric, piezoelectric (PE), and moisture-enabled nanogenerators represent promising approaches to micro-nano energy collection. These nanogenerators have seen considerable progress in material optimization and structural design. Printing technology has facilitated the large-scale manufacturing of nanogenerators. Although inks can be compatible with most traditional functional materials, this inevitably leads to a decrease in the electrical performance of the materials, necessitating control over the rheological properties of the inks. Furthermore, printing technology offers increased structural design flexibility. This review provides a comprehensive framework for ink-based nanogenerators, encompassing ink material optimization and device structural design, including improvements in ink performance, control of rheological properties, and efficient energy harvesting structures. Additionally, it highlights ink-based nanogenerators that incorporate textile technology and hybrid energy technologies, reviewing their latest advancements in energy collection and self-powered sensing. The discussion also addresses the main challenges faced and future directions for development.

Intrinsically ultralow lattice thermal conductivity and giant thermoelectric effect in Ag-based intercalated layered crystalline solids

Intrinsically ultralow lattice thermal conductivity and giant thermoelectric effect in Ag-based intercalated layered crystalline solids

Enhanced Seebeck effect in gated O-shaped Kekulé graphene junctions

The Seebeck effect in graphene with uniform Kekulé lattice distortion has been studied using the tight-binding model combined with the nonequilibrium Green's function method. The numerical results of this work show that the Seebeck coefficient of the O-shaped Kekulé graphene can be enhanced by modulating the gate voltage. At room temperature (T≈300 K), the Seebeck coefficient for the armchair nanoribbon is Sc≈1370μV/K and for the zigzag nanoribbon is Sc≈1260μV/K. At low temperature (T≈128 K), the Seebeck coefficient for the armchair nanoribbon is Sc≈2500μV/K. In addition, the nano-structuration of the O-shaped Kekulé graphene layer induces an anisotropic behavior in the Seebeck effect. Our work provides an idea for the fabrication of efficient and controllable thermoelectric effect devices.

Application requirements and design strategies of Bi2Te3‐based thermoelectric devices for low‐quality thermal energy

AbstractBismuth telluride‐based devices are capable of converting low‐quality thermal energy into electrical power via the Seebeck effect. This transformative process not only extends the spectrum of energy utilization but also significantly amplifies energy efficiency. This review serves as a comprehensive guide, elucidating the intricate design considerations essential for optimizing bismuth telluride‐based devices in both electrical and structural design. By exploring various application scenarios, it identifies critical parameters crucial for device effectiveness. Furthermore, the current landscape of thermoelectric (TE) devices is meticulously analyzed, synthesizing their developmental trajectory and contrasting it with stringent design requirements. Through this comprehensive analysis, it pinpoints key challenges that impede the maximal performance of existing TE devices. Envisioning the trajectory of bismuth telluride‐based TE materials, this review makes projections regarding their future application trends. Traversing through contemporary mechanisms and technologies, it offers practical solutions and potential avenues aimed at enhancing the efficiency of TE devices. Ultimately, this discourse endeavors to provide invaluable insights, furnishing a roadmap for the advancement and refinement of TE devices in the years ahead. By proposing feasible solutions and charting plausible directions, it aspires to stimulate innovation and drive transformative progress in the domain of TE materials and science.

Atomic-Resolution Interfacial Reaction Mechanism between Bi2Te3-Based Alloys and Ni Electrodes.

Interdiffusion and solid-solid phase reaction at the interface between thermoelectric (TE) materials and the electrode critically influence interfacial transport properties and the overall energy conversion efficiency during service. Here, the microstructural evolution and diffusion mechanisms at the interfaces between the most widely used Bi2Te3-based TE materials, n-type Bi2Te2.7Se0.3 (BTS) and p-type Bi0.5Sb1.5Te3 (BST), and Ni electrodes were investigated at atomic resolution using spherical aberration-corrected scanning transmission electron microscopy (STEM). The BTS(0001)/Ni and BST(0001)/Ni interfaces were constructed by depositing Ni nanoparticles on mechanically exfoliated BTS and BST bulk materials and subsequent annealing. The interfacial reaction is initially dominated by Ni diffusion into the TE matrix to form NiAs-type NiM intermetallics, while Ni trans-quintuple-layer diffusion only occurs in Sb-rich BST. The Bi-rich BTS is more influenced by the Ni-Te preferential reaction, resulting in NiM abnormal grain growth and the formation of tilted and rotated interfaces. Bi diffusion into the BTS matrix forms a Bi double layer at the interface or Bi2[Bi2(Te,Se)3] as the annealing temperature increases, while Bi diffusion into the Ni thin film greatly accelerates the interfacial reaction rate, as elucidated by in situ heating STEM. The results provide essential structural details to understand and prevent the degradation of TE device performance.

Thermoelectric effect in the sensors of iron and steel industry

Thermoelectric effect in the sensors of iron and steel industry

Enhancement of thermoelectric performance by stacking fault control in (GeTe)1-x(Bi2Te3)x compounds, synthesized by hot press sintering method

We investigated the thermoelectric (TE) properties of GeTe by incorporating Bi2Te3 in the GeTe system. The addition of Bi2Te3 into the GeTe matrix leads to phonon scattering caused by stacking fault or structural defect, resulting in a substantial reduction in lattice thermal conductivity κlat. We observed a significant decrease in total thermal conductivities in the vertical and horizontal pressing directions, respectively. The optimized carrier properties and low thermal conductivity in the composites have led to a remarkable improvement in the dimensionless figure of merit (zT) 1.26 at 650 K. This study highlights the potential for creating high-performance thermoelectric materials through GeTe-Bi2Te3 compounds, emphasizing the importance of defect engineering and stacking faults in reducing thermal conductivity and improving thermoelectric efficiency.

Enhancing thermoelectric properties of higher manganese silicide through facilitated non-equilibrium reactions via the introduction of additional Carbon nano-dots

Higher manganese silicide (HMS) has gained significant attention as a compelling choice for thermoelectric (TE) applications at medium temperatures due to its abundance, environmental friendliness, and impact resistance properties. Recent achievement in HMS involves leveraging the synergistic effect of energy filtering, modulation doping, and boundary scattering to enhance the TE performance. However, excellent TE properties on HMS usually demands extreme preparation processes such as shock compression, melt spinning technique, or chemical vapor transport approach, as well as the use of rare and expensive elements or nano-dots (NDs), such as Re, Ge, Ag/Pt alloy, or CsPbBr3 quantum dots. In this study, a facile wet ball milling combing with spark plasma sintering is used to streamline the synthesis processes. Relatively green, cost-effective, and accessible C NDs are used to facilitated non-equilibrium reactions and enhance TE properties of HMS. Due to the C-doped effect, the PF increased from 1.42 to 1.62 mW m−1 K−2 at 723 K, representing an approximately 14 % improvement compared to the pristine HMS. The introduction of C, derived SiC and Mn NDs result in the enhancing phonon scattering, and leading to a reduction in lattice thermal conductivity from 2.21 to 1.81 W m−1 K−1. Consequently, the figure of merit (zT) increases from 0.42 to 0.55 at 823 K, representing an enhancement of approximately ∼ 31 %. Predictably, the incorporation of C NDs into semiconductors stands as one of the effective strategies for enhancing the TE properties.

Disordered Ballistic Bismuth Nano-waveguides for Highly Efficient Thermoelectric Energy Conversion.

Junctions based on electronic ballistic waveguides, such as semiconductor nanowires or nanoribbons with transverse structural variations in the order of a large fraction of their Fermi wavelength, are suggested as highly efficient thermoelectric (TE) devices. Full harnessing of their potential requires a capability to either deterministically induce structural variations that tailor their transmission properties at the Fermi level or alternatively to form waveguides that are disordered (chaotic) but can be structurally modified continuously until favorable TE properties are achieved. Well-established methods to realize either of these routes do not exist. Here, disordered bismuth (Bi) waveguides are reported, which are both formed and structurally tuned by electromigration until their efficiency as TE devices is maximized. In accordance with theory, the conductance of the most efficient TE waveguides is in the sub quantum of conductance regime. The stability of these structures is found to be substantially higher than other actively studied devices such as single molecule junctions.

Thermoelectric effects in ballistic junctions of 2D-Weyl semimetals

Two dimensional Weyl semimetals are a variant of topological materials in two dimensions, which are realized in three atomic layer materials. These materials possess isotropic or anisotropic dispersions around Weyl nodes and present some common physical properties with their 3D counterparts. We study the thermoelectric effects in a ballistic junction of 2D-Weyl semimetal with isotropic or anisotropic dispersions around the Weyl points. We demonstrate that these two types of 2D-Weyl semimetals exhibit different thermoelectric responses at low chemical potentials of the leads. The Weyl semimetal layer’s physical characteristics can significantly affect these junctions’ thermoelectric properties. Moreover, significant Seebeck coefficient and thermoelectric figure of merit of these junctions are only observed at the low chemical potential of the leads. In particular, we unveil that thermoelectric effects in the ballistic junction of 2D-Weyl semimetals are not as efficient as their 3D counterparts.

Greatly Enhanced Thermoelectric Performance of Flexible Cu2-xS Composite Film on Nylon by Se Doping.

In this work, flexible Cu2-xS films on nylon membranes are prepared by combining a simple hydrothermal synthesis and vacuum filtration followed by hot pressing. The films consist of Cu2S and Cu1.96S two phases with grain sizes from nano to submicron. Doping Se on the S site not only increases the Cu1.96S content in the Cu2-xS to increase carrier concentration but also modifies electronic structure, thereby greatly improves the electrical properties of the Cu2-xS. Specifically, an optimal composite film with a nominal composition of Cu2-xS0.98Se0.02 exhibits a high power factor of ~150.1 μW m-1 K-2 at 300 K, which increases by ~138% compared to that of the pristine Cu2-xS film. Meanwhile, the composite film shows outstanding flexibility (~97.2% of the original electrical conductivity is maintained after 1500 bending cycles with a bending radius of 4 mm). A four-leg flexible thermoelectric (TE) generator assembled with the optimal film generates a maximum power of 329.6 nW (corresponding power density of 1.70 W m-2) at a temperature difference of 31.1 K. This work provides a simple route to the preparation of high TE performance Cu2-xS-based films.

Augmentation in the thermoelectric performance by integrating the natural minerals with synthetic tetrahedrite compounds

Thermoelectric (TE) materials-based devices are useful in converting heat into electricity. The cost of thermoelectric materials is mainly incurred from the purified pure metals used to make the efficient TE device. In the current study, tetrahedrite materials are considered due to their low cost, as these materials are abundant in mining waste of copper ores and also the most extensive sulfosalt on earth. Hence, to add value addition to mine waste materials, the composite approach has been employed to integrate the natural tetrahedrite (mine waste/tailings product) materials with synthetically developed tetrahedrite materials in the lab for the current investigation. Further, the optimum quantity of mine waste addition is optimized by the systematic investigation of TE performance with varying the mine waste percentage addition to the synthetic tetrahedrite. The p-type synthetic Cu10FeZnSb4S13 (Sample-A) tetrahedrite compound and 70 (Cu10FeZnSb4S13) + 30 (natural/mine waste) (Sample-B) have been synthesized employing hot-press at 773 K along with the pristine (Cu10Fe2Sb4S13) tetrahedrite compound. Moreover, the Seebeck coefficient is increased by 36 % (220 μV/K to 300 μV/K) for Sample-B, as compared to sample A and it is ∿ 2 times higher as compared to the pristine compound. The power factor is increased by ∿ 3 times that of the Sample-A (0.05 mW/mK2 to 0.15 mW/mK2). In addition, the thermal conductivity of Sample-B compound was further reduced by 30 % than Sample-A (0.98 W/mK to 0.69W/mK) and ∿ 44 % more than the pristine compound. Finally, the zT of Sample-B increased to almost 3 times than Sample-A (0.05–0.15).

Impact of Oxygen Stoichiometry on the Thermoelectric Properties of Bi2Sr2Co2Oy Thin Films.

In this study, we present a comprehensive analysis of the thermoelectric (TE) properties of highly c-axis-oriented thin films of layered misfit cobaltates Bi2Sr2Co2Oy. The films exhibit a high c-axis orientation, facilitating precise measurements of electronic transport and TE properties along the a-b crystallographic plane. Our findings reveal that the presence of nearly stoichiometric oxygen content results in high thermopower with metallic conductivity, while the annealing of the films in a reduced oxygen atmosphere eliminates their metallic behavior. According to the well-established Heike's limit, the thermopower tends to become temperature independent when the thermal energy significantly exceeds the bandwidth, which provides a rough estimation of charge carrier density by using the Heike's formula. This observation suggests that the dominant contribution to the thermopower comes from the narrow Co-t2g bands near the Fermi energy. Our study demonstrates that the calculated thermopower value using Heike's formula, based on the Hall electron density of the Bi2Sr2Co2Oy thin films at 300 K, aligns well with the experimental results, shedding light on the intriguing TE properties of this family of layered cobaltate oxide films.

Characterizing the 2D single atom solutions to capture CO2 by the digital twin model

The digital twin model is developed to characterize the CO2 capture by the Cu and B 2D single atom solution (2DSAS). The key digital functions distributions f[], g[] and h[] characterize the physical 2DSAS system with the digital code 1 and 0. The thermoelectrical effect of the 2DSAS is analyzed. The digital code combinations of Cu atoms sorting from 1111 to 11,111 with B atoms sorting from 00 to 000 were identified as more suitable for CO2 capture. The effects of velocity difference of Cu and B atoms, temperature and CO2 loading were discussed. CO2 desorption efficiency was increased by an average 4.2 % and the energy consumption of desorption was reduced by 35.4 % at h[] of 3.5 × 10-6 m/s to 5 × 10-6 m/s. The 2DSAS of Cu and C, Cu and N and Cu and Si were suggested for CO2 capture.

Multi-Stage Thermoelectric Coolers Current Optimization for Infrared Detectors Based on the SNOPT-Finite Element Method

At present, series power supply has been widely used in multi-stage thermoelectric coolers (TEC), however, the series power supply cannot fully utilize the full cooling capability of multi-stage TEC. In this paper, according to the actual working conditions of IR detector coolers, three multi-stage TEC models with different numbers of stages were established, and a new method of SNOPT-FEM coupled analysis was adopted to individually optimize the current of each stage. The method considers the synergistic influence of inter-stage thermoelectric effects, which makes the simulation results closer to reality and improves the model solution efficiency with the help of algorithms, which shortens the computation time by at least 46%. The results show that the cold side temperatures of 3-stage, 4-stage, and 5-stage thermoelectric coolers with separated and separated algorithmic power supply can be reduced by 7.95 K and 8.59 K, 8.20 K and 9.04 K and 8.37 K and 9.13 K, respectively, compared with the series power supply. The large cooling temperature difference under separated and separated algorithmic power supplies was achieved at the expense of more power consumption and lower COP compared with the series power supply. Therefore, high-power sources are required to meet the cooling needs of IR detectors in engineering applications. It is thus evident that the proposed method is favorable to promote the application of thermoelectric cooling in infrared detection.

Spin Transport in High‐Field Superconductors

AbstractHigh‐field superconductors are characterized by a spin splitting of the density of states, giving rise to spin transport phenomena. This includes spin‐polarized tunneling, spin‐dependent thermoelectric effects, long‐range quasiparticle spin transport, and spin‐dependent coupling of supercurrents and quasiparticles. This review gives a brief overview of the theory background, recent experimental progress in the field, and an outlook on open problems and possible applications.

Thermoelectric Performance of Hybrid Inorganic/Organic Composites Based on PEDOT:PSS/Tin(II) Oxide.

PSS(poly(3,4-ethylenedioxylthiophene):poly(styrenesulfonate))-based composites often exhibit remarkable characteristics regarding high electrical conductivity and great processability, being a suitable candidate for thermoelectric (TE) applications. To increase its performance, PEDOT:PSS is commonly blended with scarce and toxic inorganic compounds based on Se, Te or Bi. In this work we propose the use of one p-type metal oxide semiconductor (MOs): tin(II) oxide (SnO), motivated by its abundance and low toxicity. Hybrid PEDOT:PSS/SnO composites were obtained by firstly blending Ethylene glycol (EG) with PEDOT:PSS and then by adding p-type SnO, previously synthesized by a chemical route. The mixture was deposited via spin-coating onto glass substrates. The Power Factor (PF) of the composites increased by a factor of 300 with the combined EG/SnO composition.

Tuning thermoelectric performance with N-annulated perylene-based small molecules and single-walled carbon nanotube nanocomposite films

Two N-annulated perylene (NP)-based organic small molecules (OSMs) with end groups of di-p-tolylamine (DTA) and phenyl-di-p-tolylamine (PhDTA), namely DDTANP and DPhDTANP, are incorporated into single-walled carbon nanotubes (SWCNTs) to fabricate nanocomposite thin films for thermoelectric (TE) application. The weight ratios of OSMs to SWCNTs range from 1:1 to 1:4. The inherent planar structures of these novel OSMs facilitate strong π-π interactions and charge transfer with SWCNTs. Specifically, the DDTANP/SWCNT nanocomposite films, due to its lower HOMO, induces pronounced energy filtering and, thus, a high Seebeck coefficient (S). At the optimized weight ratio of 1:3, DDTANP/SWCNT nanocomposite thin film exhibits an electrical conductivity (σ) of 214.7 S cm−1, and S of 59.8 μV K−1. The flat structure of DPhDTANP enhances its adhesion to SWCNTs, thereby improving dispersion and increasing σ. Similarly, the DPhDTANP/SWCNT (1:3) nanocomposite thin film achieves 256.4 S cm−1, and an S of 55.8 μV K−1. The DPhDTANP/SWCNT (1:3) nanocomposite film exhibits higher σ, resulting in a power factor (PF) of 79.8 μW m−1 K−2, surpassing the PF of 76.7 μW m−1 K−2 for the DDTANP/SWCNT (1:3) nanocomposite film. These findings offer valuable insights into molecular design for SWCNTs-based composite TE research and contributed to enhancing TE applications.

DFT investigation of optoelectronic and thermoelectric features of Ba2Ce(Sn,Pt)O6 double perovskites

This study explores the geometric and thermodynamic stability, optoelectronic, and thermoelectric attributes of Ba2Ce(Sn,Pt)O6 double perovskites (DPs) through first-principles calculations. Both DPs exhibit stable cubic structures. Ba2CeSnO6 displays a bandgap of approximately 2.1 eV, indicating semiconductive behavior, while Ba2CePtO6 features a narrower bandgap of around 0.41 eV. This electronic behavior of both DPs is mainly influenced by the emergence of Ce-4f flat bands. Analysis of optical properties reveals absorption peaks at 3.4 eV for Ba2CeSnO6 and 1.2 eV for Ba2CePtO6, suggesting potential applications in visible and ultraviolet light optoelectronics. Additionally, the thermoelectric (TE) investigation demonstrates promising results, with high Seebeck coefficients (S) of 170 for Ba2CeSnO6 and 221 μV/K for Ba2CePtO6 at room temperature. The computed thermoelectric figure of merit (zT) exhibits a relatively stable trend for temperatures greater than 300 K, reaching 0.66 for Ba2CeSnO6 and 0.74 for Ba2CePtO6 at 800 K. This research provides valuable insights into the potential applications of these double perovskites in emerging technologies including visible light photonics and thermoelectric generators.

Quantitative analysis of silicon photomultipliers for thermoluminescence measurement

The employment of silicon photomultipliers (SiPMs) in photon detection systems facilitates the reduction of detection module size, enhances portability and ruggedness, and lowers product costs. This study investigated the potential of SiPM in thermoluminescence (TL) measurements, focusing on its detection limits, temperature dependency, and dose responses. A 3 × 3 mm2 multi-pixel photon counter (MPPC, Hamamatsu MPPC) composed of 50 μm single-photon avalanche diodes (SPADs) was utilized in single-photon counting mode as the detector. This experimental setup was compared with a conventional photomultiplier tube (PMT) in TL readout case. To ensure comparable light exposure between the two detectors, a 3-mm diameter pinhole was positioned in front of the PMT. By using a thermoelectric (TE) cooling module to maintain the sensor temperature at −20 °C, signal reproducibility was achieved with a fluctuation of less than 1.2%, and a detection limit ranging from 30 to 300 μGy was assessed for four dosimeters: LiF:Mg,Ti, LiF:Mg,Cu,P, LiF:Mg,Cu,Si, and Al2O3:C. The dose response of the system was limited by significant signal saturation due to pile-up effects. We introduced a correction model with a 50 ns paralyzable deadtime, which enhanced the signal response by more than 20-fold. Furthermore, this model also correlated well with the observed count rates under high dark count rate (DCR) conditions up to 1.67 MHz. The findings from this study further contributes to the discussion regarding the perspective of SiPM as TL detectors.