Thermoelectric Generator Research Articles

Superior bendability enabled by inherent in-plane elasticity in Bi2Te3 thermoelectrics

With the rapid development of modern wearable electronics, powerful and deformable thermoelectric generators have become an urgent need as the power units that convert environmental or body heat into electricity. Existing efforts mostly focused on the assistance for deformability by substrates/additives, the resultant devices usually output much less power and showed very poor power retainment. Elasticity is inherent to all solids, which therefore offers an intrinsic solution for making thermoelectrics deformable without compromise in power output because of its full recoverability. This work demonstrates this in best-performing (Bi, Sb)2(Te, Se)3 thermoelectrics near room temperature, ending up in the film devices with both extraordinary power density and robust recoverable bendability. This originates from the inherent large elasticity for the in-plane orientation, which is enabled by an easy tape stripping approach for the Van der Waals layered structure, allowing the realization of both powerfulness and bendability that are equally important for wearable thermoelectrics.

Self-Powered Standalone Performance of Thermoelectric Generator for Body Heat Harvesting

Self-Powered Standalone Performance of Thermoelectric Generator for Body Heat Harvesting

Enhancing Photovoltaic Systems with Integrated Thermoelectric Generators: Real-Time Optimization through Arduino Implementation

Enhancing Photovoltaic Systems with Integrated Thermoelectric Generators: Real-Time Optimization through Arduino Implementation

Cooperative Nernst effect of multilayer systems: Parallel circuit model study

Transverse thermoelectric power generation has emerged as a topic of immense interest in recent years owing to the orthogonal geometry which enables better scalability and fabrication of devices. Here, we investigate the thickness dependence of longitudinal and transverse responses in film-substrate systems, i.e., the Seebeck coefficient, the Hall coefficient, the Nernst coefficient, and the anomalous Nernst coefficient in a unified and general manner based on the circuit model, which describes the system as the parallel setup. By solving the parallel circuit model, we show that the transverse responses exhibit a significant peak, indicating the importance of a cooperative effect between the film and the substrate, arising from circulating currents that occur in these multilayer systems in the presence of a temperature gradient. Finally, on the basis of realistic material parameters, we predict that the Nernst effect in bismuth thin films on doped silicon substrates is boosted to unprecedented values if the thickness ratio is tuned accordingly, motivating experimental validation. Published by the American Physical Society 2024

Enhancing the Performance of Oxide‐Based Transverse Thermoelectric Generators by Optimized Internal Geometry

AbstractIn transverse thermoelectric generators (TTEGs), comprising an artificially anisotropic material formed by a layered and tilted structure of two materials, the induced thermoelectric voltage is generated perpendicular to the applied temperature gradient. The performance of TTEGs composed of alternate layers of La1.99Sr0.01CuO4 (LSCO) and silver (Ag), tilted at an angle φ, with metal‐to‐ceramic thickness ratio νt, is investigated. Improvement in performance is achieved by optimizing the internal geometry parameters, φ and νt of the tilted layered structure. The transverse power factor PFtr and figure‐of‐merit ZtrT of the artificially tilted material composite are analytically calculated and presented in color contours. Experimentally, a power output Pout of 14.5 mW at ΔT = 140 K is measured for a TTEG with φ = 66°, compared to 2.8 mW and 11 mW for generators with φ of 20° and 45°, respectively. Moreover, TTEGs with different values of νt are prepared. Furthermore, transverse multilayer thermoelectric generators (TMLTEG) with output power of 14.3 mW at ΔT = 225 K are fabricated utilizing the ceramic multilayer technology. It is demonstrated that the transverse thermoelectric effect using an artificial anisotropic material consisting of ceramic and metal can be explored for autonomous thermoelectric energy generation for low‐power applications.

Self-powered wireless sensor system utilizing a thermoelectric generator for photovoltaic module monitoring application

In this work, we demonstrate a self-powered wireless PV module monitoring system that utilizes a thermoelectric generator (TEG) to convert residual thermal energy from the PV module into electrical power. We investigated the TEG performance with and without the heat sink. Results show that the temperature difference between the hot and cold sides of the TEG increased to 7.2 °C with the heat sink, compared to only 1 °C without it, at a hot side temperature of 50 °C. We integrated the TEG/heat sink with the PV module, which served as the heat source, achieving a maximum output power of 0.981 mW at a voltage of 0.06 V under a temperature gradient of 3.6 °C in a 1 sun condition. We successfully demonstrated a self-powered wireless PV monitoring sensor system by integrating a step-up voltage converter, microcontroller, IR thermometer, Bluetooth communication module, and the TEG/heat sink, which generated sufficient power for the monitoring system operation. The findings introduce a novel solution for wireless PV module monitoring that operates independently of grid connections or battery power. This innovation not only signifies advancements in renewable energy management but also opens new opportunities in the Internet of Things (IoT) sector.

Realizing Ultrahigh Conversion Efficiency of ≈9.0% in YbCd2Sb2/Mg3Sb2 Zintl Module for Thermoelectric Power Generation.

Recently, YbCd2Sb2-based Zintl compounds have been widely investigated owing to their extraordinary thermoelectric (TE) performance. However, its p orbitals of anions that determined the valence band structure are split due to crystal field splitting that provides a good platform for band manipulation by doping/alloying and, more importantly, the YbCd2Sb2-based device has yet to be reported. In this work, single-phase YbCd1.5Zn0.5Sb2 is successfully obtained through precise chemical composition control. Then, YbMg2Sb2-alloying increases the cationic vacancy defect formation energy and further optimizes carrier concentration. Moreover, the band structure of YbCd1.5Zn0.5Sb2 is subtly manipulated, and the underlying mechanism is experimentally explored. Combined with the reduced lattice thermal conductivity, a high peak ZT value of ∼1.43 at 700K is obtained for YbCd1.425Zn0.475Mg0.1Sb2. Subsequently, choosing Fe90Sb10 as the diffusion barrier layer and adopting the transient liquid phase bonding technique, for the first time, it is demonstrated that YbCd2Sb2/Mg3(Sb, Bi)2 TE module with an ultrahigh conversion efficiency of ≈9.0% at a heat difference of 430K. More importantly, this module displays good thermal stability. This work paves the way for YbCd2Sb2 materials and devices in mid-temperature heat recovery.

Boosting performance of heat-source free water-floating thermoelectric generators by controlling wettability by mixing single-walled carbon nanotubes with α-cellulose

Thermoelectric generation (TEG) using single-walled carbon nanotubes (SWCNTs), which generate electricity simply by floating on the surface of water, is promising and has novel features that are not found in conventional TEG systems. However, water-floating SWCNT-TEGs generate only a small voltage owing to the hydrophobic nature of SWCNTs. In this study, to increase their output voltage, we added α-cellulose, which is hydrophilic in nature, to the SWCNT films for enhancing water evaporative thermal cooling, leading to an increase in the temperature gradient in the TEGs. When the TEGs were exposed to artificial sunlight, the TEG with SWCNT/α-cellulose (0.6 g) films exhibited the highest output voltage of 1.0 mV, which was more than three times higher than that exhibited for the SWCNT-TEG without α-cellulose. This phenomenon can be explained by the hydrophilic nature of the films, which increases the amount of water pumped to the film surface and enhances the evaporative cooling effect as this water evaporates, thereby creating a larger temperature difference within the TEGs. The results show their significant potential as a power source for sensors such as those monitoring water flow in water environments.

Two-dimensional BiSbTeX2 (X = S, Se, Te) and their Janus monolayers as efficient thermoelectric materials.

Today, there is a huge need for highly efficient and sustainable energy resources to tackle environmental degradation and energy crisis. We have analyzed the electronic, mechanical and thermoelectric (TE) characteristics of two-dimensional (2D) BiSbTeX2 (X = S, Se and Te) and Janus BiSbTeXY (X/Y = S, Se and Te) monolayers by implementing first principles simulations. These monolayers' dynamic stability and thermal stability have been demonstrated through phonon dispersion spectra and ab initio molecular dynamics (AIMD) simulations, respectively. The band structure of these monolayers can be tuned by applying uniaxial and biaxial strains. The investigated lattice thermal conductivity (κl) for these monolayers lies between 0.23 and 0.37 W m-1 K-1 at 300 K. For a more precise calculation of the scattering rate, we implemented electron-phonon coupling (EPC) and spin-orbit coupling effects to calculate the transport properties. For p(n)-type carriers, the power factor of these monolayers is predicted to be as high as 2.08 × 10-3 W m-1 K-2 and (0.47 × 10-3 W m-1 K-2) at 300 K. The higher thermoelectric figure of merit (ZT) of p-type carriers at 300 K is obtained because of their very low value of κl and high power factor. Our theoretical investigation predicts that these monolayers can be potential candidates for fabricating highly efficient thermoelectric power generators.

Probing the structural, mechanical, electro-magnetic, thermodynamic and thermoelectric properties of inner-transition based RaXO3 (X: Pr and U) cubic perovskites via first principle calculations

Here, we present ab-initio calculations of the structural, mechanical, electronic, magnetic, thermodynamic and thermoelectric properties of two radium-based perovskites by using density functional theory. These compounds are cubic in nature. Computation of tolerance factor, structural optimization by using the equation of state assures the stability of the materials. Further, we have checked the mechanical stability of the materials by computing the different mechanical parameters. The observed data of B/G and Cauchy pressure for the present materials reveals the ductile nature. The spin polarized band structures and density of states illustrate the half-metallic nature of these materials with the band gap of (3.74 and 4.80) eV in spin down channel for RaPrO3 and RaUO3 alloys respectively. The total magnetic moments calculated via GGA and mBJ approximations were found to be integral in nature (1 and 2) μB, for RaPrO3 and RaUO3 alloys respectively which also is an indication of the half-metallic character of these materials. The effect of temperature and pressure on the different thermodynamic properties like the specific heat capacity, thermal expansion and Gruneisen parameter were studied using the quasi-harmonic Debye model. Finally, we have speculated the temperature dependent thermoelectric properties in terms of Seebeck coefficient, electrical conductivity, thermal conductivity and power factor. The summed -up properties suggest the applications of these materials in thermoelectrics, spintronics and thermoelectric generators outlooks.

Effect of Heatsink Material on the Efficiency of Solar Panel-Thermoelectric Hybrid Devices

Solar panels exposed to solar radiation will produce heat, affecting their efficiency. A solution to this problem is integrating solar panels with thermoelectric generators that can convert thermal energy into electrical energy. In general, thermoelectric generators are equipped with heatsinks as heat absorbers. Many studies only look at the addition of heatsinks without examining the effect of the type of heatsink material used. Based on this background, this study identifies the effect of heatsink materials on the efficiency produced by solar panel thermoelectric devices. The purpose of this study is to determine which heatsink material can produce high efficiency in solar panel-thermoelectric devices. This research is useful for improving the efficiency of solar-thermoelectric hybrid devices. The novelty of this study is the selection of various heatsink materials that are directly tested against the efficiency of hybrid devices. The heatsink materials tested in this study were aluminum and copper. The equipment was tested by measuring the current and voltage generated by the solar panel-thermoelectric using a multimeter which was then used to calculate its power. The results showed that the hybrid solar panel-thermoelectric device with a heatsink made of copper produced a higher output power of 1.882 mW compared to aluminum material which was only 0.513 mW.

Ductile (Ag,Cu)2(S,Se,Te)-based auxetic metamaterials for sustainable thermoelectric power generation

Sustainable energy solution has resulted in significant interest in thermoelectric power generation, converting waste heat into electricity. However, the practical application of thermoelectric generators has been hindered by issues with their adaptability to arbitrary heat sources and durability in an operational environment. Here, we propose deformable auxetic thermoelectric metamaterials composed of high-entropy (Ag,Cu)2(S,Se,Te) ductile alloys, realized using finite element modelling and three-dimensional (3D) printing. We design a re-entrant auxetic structure with a negative Poisson’s ratio to maximize the mechanical deformability and develop an (Ag,Cu)2(S,Se,Te) particle-based colloidal 3D printable ink, tailored with Te microparticles. The 3D-printed (Ag,Cu)2(S,Se,Te) alloy exhibit a ZT value of 1.15 coupled with high compressive strength (208 MPa) and fracture strain (17.5 %). The fabricated auxetic metamaterials exhibit excellent vibrational stability and adaptability to diverse curved surfaces, realizing efficient power generation on a synclastic curved heat source. Our approach offers a method to design durable and efficient heat recovery devices.

Large Nernst effect in a layered metallic antiferromagnet EuAl2Si2

The large Nernst effect is advantageous for developing transverse Nernst thermoelectric generators or Ettingshausen coolers within a single component, avoiding the complexity of electron- and hole-modules in longitudinal Seebeck thermoelectric devices. We report a large Nernst signal reaching 130 μV/K at 8 K and 13 T in the layered metallic antiferromagnet EuAl2Si2. Notably, this large transverse Nernst thermopower is two orders of magnitude greater than its longitudinal counterpart. The Nernst coefficient peaks around 4 and 8 K at 3 and 13 T, respectively. At similar temperatures, both the Hall coefficient and the Seebeck signal change sign. Additionally, nearly compensated electron- and hole-like carriers with high mobility (∼ 4000 cm2/V s at 4 K) are revealed from the magnetoconductivity. These findings suggest that the large Nernst effect and vanishing Seebeck thermopower in EuAl2Si2 are due to the compensated electron- and hole-like bands, along with the high mobility of the Weyl band near the Fermi level. Our results underscore the importance of band compensation and topological fermiology in achieving large Nernst thermopower and exploring potential Nernst thermoelectric applications at low temperatures.

Tri-objective and multi-parameter geometric optimization of two-stage radioisotope thermoelectric generator based on NSGA-II

Radioisotope thermoelectric generator (RTG) is one of ideal power sources for deep space exploration due to the long service life and high stability. To further extend service life and improve electrical output, this study is first to simultaneously optimize electrical output and mechanical stability induced by thermal stress of the two-stage RTG using non-dominated sorting genetic algorithm-II. Skutterudite and bismuth telluride are used as the thermoelectric materials in hot-stage and cold-stage thermoelectric generators, respectively. The maximum von Mises stress of the skutterudite-stage (VonSKD) and bismuth telluride-stage (VonBT) thermoelectric generator and the conversion efficiency of the two-stage RTG (ηtwo) are set to the three objectives, and twelve geometrical parameters of two-stage RTG are used as variables. Electrical output and mechanical stability are simulated with COMSOL 6.0 Multiphysics software based on the finite element method. Results show that the ranges of ηtwo, VonSKD, and VonBT in the Pareto front are 4.81–7.57 %, 112.2–228.46 and 19.24–87.33 MPa, respectively, when the temperature difference is 300 K. TOPSIS decision-making method is used to select the specific optimal solution on the Pareto front according to the weight of the different objectives. Comparisons between tri- and bi-objective as well as single-stage optimization are also carried. Results show that there are strong influences among these three objectives. The performance of one objective would improve at the expense of the performance of the remaining objectives decrease if a larger weight was given. The VonSKD has the greatest importance among the three objectives, followed by ηtwo, and the smallest is VonBT. Skutterudite-stage thermoelectric generator should be particularly considered in the design of two-stage RTGs. The two-stage RTGs with different weight factors exhibit different electrical performances due to different geometrical parameters. This research can provide references for two-stage thermoelectric generators in more scenarios to improve electrical performances and extend service life.

The Graph Becomes the Dataset: Compiling Historical and Current RTG Data into One Place

Radioisotope thermoelectric generator (RTG) technology has a very long and incredibly successful history of providing heat and power to some of humankind’s most successful space exploration missions. Members of the community that support and maintain this technology often like to show the entire history of RTG performance on “The Graph.” Meant to impress, The Graph does its job in that regard. Unless you were connected to the right people, however, it was very difficult to get a copy of The Graph or its underlying data. This made it difficult for many to dive into the technical details or evaluate individual RTG performance from historical missions. To make matters worse, the performance for several missions in The Graph were incomplete. In 2020, with a little extra time on their hands thanks to COVID, the authors reached throughout the RTG community to locate and collate the missing RTG data. This information was then published as an open-source tabular Dataset. Users can now build their own version of The Graph or use the data for a more detailed analysis of RTG performance. Updates to the currently operating missions in The Dataset are expected to occur on a roughly annual basis. This Dataset represents the most comprehensive, authoritative, up-to-date repository of all RTG performance available today.

Boosting self-powered wearable thermoelectric generator with solar absorber and radiative cooler

The electrical output of wearable thermoelectric generators (wTEGs) has traditionally been constrained by small temperature differentials when powering microelectronics. In this study, we innovatively combine photothermal and radiative cooling mechanisms within a single wTEGs system, enabling substantial, uninterrupted power generation. Specifically, we designed a multilayer selective solar absorber (m-SSA) composed of flexible dielectric-metal stacks. This absorber demonstrates exceptional solar absorption efficiency of 93 % and significantly low thermal emissivity of 10 %. In practical outdoor conditions, it achieves a temperature increase of up to 108 °C under solar irradiation. Concurrently, we developed a flexible hierarchically porous radiative cooler (HP-RC), which reflects 96 % of solar energy and emits 97 % of thermal energy, achieving a cooling differential of up to 10 °C, even at ambient temperatures of 42 °C. Integration of the m-SSA and HP-RC with wTEGs allows for the simultaneous harvesting of heat from solar, cold space, and earth (robots or human body). This novel energy capture mechanism yielded a notable power density of 198 mW/m² for human body and 52 mW/m2 for steel robots in outdoor wearable applications. This significant advancement promotes the field toward high-performance, integrated green power technologies and holds promise for next-generation wearable self-powered devices.

Comparative Analysis and Integrated Methodology for the Electrical Design and Performance Evaluation of Thermoelectric Generators (TEGs) in Energy Harvesting Applications

Comparative Analysis and Integrated Methodology for the Electrical Design and Performance Evaluation of Thermoelectric Generators (TEGs) in Energy Harvesting Applications

Cost‐Effective Approach to Fabricate Oxide‐Based Bulk Thermoelectric Generator for Low‐Grade Waste Heat Harvesting

Oxide materials are well explored in thermoelectric and optoelectronic device applications due to their wide range of tunable properties, thermal stability, compatibility with other materials, nontoxicity, and earth abundancy. As a result, it can often be integrated into devices, which facilitates the development of oxide‐based thermoelectric generators at low cost. In this work, we synthesized BaxCoO2 and graphene‐doped In2O3 by solid‐state reaction route and then incorporated them in thermoelectric generator for the first time. A preliminary 3‐couple device is designed on a glass substrate. Here, the unique aspect is that graphite paint is used for the first time to make contact between oxide and metal electrodes instead of earlier used soldering and diffusion techniques, which prevents metals from diffusing in the oxide matrix. This device generates an open‐circuit voltage of 30 mV whereas it produces an output power of 0.3 μW with power density of ≈15.5 nW cm−2 for ΔT of 60 K, which is comparable to earlier reported metal‐based Bi0.5Se1.5Te3/Bi2Se0.3Te2.7TE devices. Further, the physical dimensions of the generators can be adjusted and the temperature gradient can be increased to get the desired power. This work offers a promising strategy for the development of thick as well as thin thermoelectric generators at an affordable cost.

Thermodynamic and economic analysis of a novel solid oxide fuel cell, two level thermoelectric generator and double effect parallel absorption chiller integrated system

This study presents a comprehensive thermodynamic and economic analysis of a novel hybrid energy system integrating a Solid Oxide Fuel Cell (SOFC) with a Two-Level Thermoelectric Generator (TTEG) and a Double-Effect Parallel Absorption Chiller (DEPAC) for enhanced waste heat recovery. The primary objective is to maximize energy utilization and overall efficiency by leveraging the synergetic effects of these components. Unlike previous studies, this research uniquely evaluates the effectiveness of the integrated system and examines the impact of different Absorption Chiller configurations and the number of TTEG elements, filling a critical gap in the literature. The proposed system achieves a net electrical efficiency of 42.88 %, an energy efficiency of 44.61 %, and an exergy efficiency of 57.16 % under optimal conditions. This marks a significant improvement compared to standalone SOFC systems, with the TTEG effectively harnessing waste heat and contributing an additional 0.680 kW/m2 to the overall power output. The integration of the DEPAC system further enhances performance by providing cooling with a Coefficient of Performance (COP) of 1.351. The economic analysis reveals a positive Net Present Value (NPV) of $1,993,136, a Dynamic Payback Period (DPP) of 6.7 years, and a Levelized Cost of Electricity (LCOE) of $59/MWh, underscoring the system's financial viability. These findings demonstrate that the hybrid system offers a sustainable and efficient solution for power generation and waste heat recovery, aligning with the broader goals of advancing renewable energy technologies and setting a new benchmark in hybrid energy system design and optimization.

Achieving High Thermoelectric Performance in Bi2(Te, Se)3 Thin Film with (00l)-Oriented by Incorporating Tellurization and Selenization Processes.

Flexible thermoelectric (TE) generators have received great attention as a sustainable and reliable option to convert heat from the human body and other ambient sources into electricity. This study provides a synthesis route that involves thermally induced diffusion to introduce Te and Se into Bi, fabricating an n-type Bi-Te-Se flexible thin film on a flexible substrate. This specific synthesis alters the crystal orientation (00l) of the thin film, improving in-plane electrical transportation and optimizing carrier concentration. Consequently, BixTeySe0.42 enhanced both the Seebeck coefficient and electrical conductivity, achieving a power factor of 17.1 μW cm-1 K-2 at room temperature. The TE device assembled with p-type Sb2Te3 exhibited exceptional flexibility with only a 26.2% change in resistance after 1000 times of bending at a radius of about 6 mm. The resistance change was further reduced to 7.5% after the application of a vinyl laurate coating. The fabricated TE device generated an ultrahigh output power of 792 nW with a temperature difference of 30 K.