Thermoelectric Energy Harvesting for Exhaust Waste Heat Recovery: A System Design.

Thermal energy harvesting for high-speed moving objects is particularly promising in providing an efficient and sustainable energy source to enhance operational capabilities and endurance. Thermoelectric (TE) technology, by exploiting temperature gradients between a heat source and ambient temperature, can provide a continuous power supply to such systems, reducing the reliance on conventional batteries and extending operation times. However, the integrated thermoelectric generator (TEG) system design research is far behind materials development.

Underwater Thermoacoustic Generation by a Hierarchical Tetrapodal Carbon Nanotube Network.

Solid-state fabricated carbon nanotube (CNT) sheets have shown promise as thermoacoustic (TA) sound generators, emitting tunable sound waves across a broad frequency spectrum (1-10 Hz) due to their ultralow specific heat capacity. However, their applications as underwater TA sound generators are limited by the reduced mechanical strength of CNT sheets in aqueous environments. In this study, we present a mechanically robust underwater TA device constructed from a three-dimensional (3D) tetrapodal assembly of carbon nanotubes (t-CNTs).

Brookite TiO Nanorods as Promising Electrochromic and Energy Storage Materials for Smart Windows.

Electrochromic smart windows (ESWs) offer an attractive option for regulating indoor lighting conditions. Electrochromic materials based on ion insertion/desertion mechanisms also present the possibility for energy storage, thereby increasing overall energy efficiency and adding value to the system. However, current electrochromic electrodes suffer from performance degradation, long response time, and low coloration efficiency.

Toward Chiral Lasing from All-Solution-Processed Flexible Perovskite-Nanocrystal-Liquid-Crystal Membranes.

Circularly polarized (CP) coherent light sources are of great potential for various advanced optical applications spanning displays/imaging to data processing/encryption and quantum communication. Here, the first demonstration of CP amplified spontaneous emission (ASE)/lasing from a free-standing and flexible membrane device is reported. The membrane device consists of perovskite nanocrystals (PNCs) and cholesteric liquid crystals (CLCs) layers sandwiched within a Fabry-Pérot (F-P) cavity architecture.

High-Performance Thermomagnetic Gd-Si-Ge Alloys.

Exploring low-grade waste heat energy harvesting is crucial to address increasing environmental concerns. Thermomagnetic materials are magnetic phase change materials that enable energy harvesting from low-temperature gradients. To achieve a high thermomagnetic conversion efficiency, there are three main material requirements: (i) magnetic phase transition near room temperature, (ii) substantial change in magnetization with temperature, and (iii) high thermal conductivity.

Half-Heusler alloys as emerging high power density thermoelectric cooling materials.

To achieve optimal thermoelectric performance, it is crucial to manipulate the scattering processes within materials to decouple the transport of phonons and electrons. In half-Heusler (hH) compounds, selective defect reduction can significantly improve performance due to the weak electron-acoustic phonon interaction. This study utilized Sb-pressure controlled annealing process to modulate the microstructure and point defects of NbTaTiFeSb compound, resulting in a 100% increase in carrier mobility and a maximum power factor of 78 µW cm K, approaching the theoretical prediction for NbFeSb single crystal.

Thermoelectric Performance of Surface-Engineered CuTe-CuSe Nanocomposites.

CuS and CuSe have recently been reported as promising thermoelectric (TE) materials for medium-temperature applications. In contrast, CuTe, another member of the copper chalcogenide family, typically exhibits low Seebeck coefficients that limit its potential to achieve a superior thermoelectric figure of merit, , particularly in the low-temperature range where this material could be effective. To address this, we investigated the TE performance of CuTe-CuSe nanocomposites by consolidating surface-engineered CuTe nanocrystals.

Toward High Conversion Efficiency of Thermoelectric Modules through Synergistical Optimization of Layered Materials.

Waste-heat electricity generation using high-efficiency solid-state conversion technology can significantly decrease dependence on fossil fuels. Here, a synergistical optimization of layered half-Heusler (hH) materials and module to improve thermoelectric conversion efficiency is reported. This is realized by manufacturing multiple thermoelectric materials with major compositional variations and temperature-gradient-coupled carrier distribution by one-step spark plasma sintering.

High-Performance Skutterudite/Half-Heusler Cascaded Thermoelectric Module Using the Transient Liquid Phase Sintering Joining Technique.

Thermoelectric (TE) materials have made rapid advancement in the past decade, paving the pathway toward the design of solid-state waste heat recovery systems. The next requirement in the design process is realization of full-scale multistage TE devices in the medium to high temperature range for enhanced power generation. Here, we report the design and manufacturing of full-scale skutterudite (SKD)/half-Heusler (hH) cascaded TE devices with 49-couple TE legs for each stage.

Defect-Engineering-Stabilized AgSbTe with High Thermoelectric Performance.

Thermoelectric (TE) generators enable the direct and reversible conversion between heat and electricity, providing applications in both refrigeration and power generation. In the last decade, several TE materials with relatively high figures of merit (zT) have been reported in the low- and high-temperature regimes. However, there is an urgent demand for high-performance TE materials working in the mid-temperature range (400-700 K).

A universal all-solid synthesis for high throughput production of halide perovskite.

Halide perovskites show ubiquitous presences in growing fields at both fundamental and applied levels. Discovery, investigation, and application of innovative perovskites are heavily dependent on the synthetic methodology in terms of time-/yield-/effort-/energy- efficiency. Conventional wet chemistry method provides the easiness for growing thin film samples, but represents as an inefficient way for bulk crystal synthesis.

Development of Tetrapod Zinc Oxide-Based UV Sensor for Precision Livestock Farming and Productivity.

In order to ensure the health and welfare of livestock, there has been an emphasis on precision farming of ruminant animals. Monitoring the life index of ruminant animals is of importance for intelligent farming. Here, a wearable sensor for monitoring ultraviolet (UV) radiation is demonstrated to understand the effect of primary and secondary photosensitization on dairy animals.

Conformal High-Power-Density Half-Heusler Thermoelectric Modules: A Pathway toward Practical Power Generators.

Thermoelectric generators (TEGs) exploiting the Seebeck effect provide a promising solution for waste heat recovery. Among the large number of thermoelectric (TE) materials, half-Heusler (hH) alloys are leading candidates for medium- to high-temperature power generation applications. However, the fundamental challenge in this field has been inhomogeneous material properties at large wafer diameters, insufficient power output from the modules, and rigid form factors of TE modules.

Bismuth Telluride Thermoelectrics with 8% Module Efficiency for Waste Heat Recovery Application.

Thermoelectric generators (TEGs) offer cost-effective and sustainable solid-state energy conversion mechanism from wasted heat into useful electrical power. Thermoelectric (TE) materials based upon bismuth telluride (BiTe) systems are widely utilized in applications ranging from energy generation to sensing to cooling. There is demand for BiTe materials with high figure of merit (zT) and TEG modules with high conversion efficiency over intermediate temperatures (25°C-250°C).

Understanding Oxidation Resistance of Half-Heusler Alloys for in-Air High Temperature Sustainable Thermoelectric Generators.

High temperature waste heat recovery has gained tremendous interest to generate useful electricity while reducing the harmful impact on the environment. Thermoelectric (TE) solid-state materials enable direct conversion of heat into electricity with high efficiency, thereby offering a practical solution for waste heat recovery. Half-Heusler (hH) alloys are the leading TE materials for medium to high temperature applications, as they exhibit a high figure of merit and mechanical strength at temperatures as high as 973 K.

High-Performance Thermoelectric Generators for Field Deployments.

Thermoelectric power generation is a reliable energy harvesting technique for directly converting heat into electricity. Recent studies have reported the thermal-to-electrical energy conversion efficiency of thermoelectric generators (TEGs) up to 11% under laboratory settings. However, the practical efficiency of TEGs deployed under real environments is still not more than a few percent.

Filiform Metal Silver Nanoinclusions To Enhance Thermoelectric Performance of P-type CaCoO Oxide.

Cd doping and metallic Ag additives in CaCoO polycrystalline materials are shown to result in improved thermoelectric (TE) transport properties. Carrier concentration and mobility were optimized through the combination of doping and compositional modulation approaches. The formation of filiform Ag nanoinclusions between the interlayers and grain boundaries enhances the anisotropic carrier transport, leading to higher carrier mobility.

High Power Density Body Heat Energy Harvesting.

Thermoelectric generators (TEGs) can convert body heat into electricity, thereby providing a continuous power source for wearable and implantable devices. For wearables, the low fill factor (area occupied by legs over the TEG base area) TEG modules are relevant as they provide large thermal gradient across the legs and require less material, which reduces the cost and weight. However, TEGs with a fill factor below 15% suffer from reduced mechanical robustness; consequently, commercial modules are usually fabricated with a fill factor in the range of 25-50%.

Nanoscale Texturing and Interfaces in Compositionally Modified CaCoO with Enhanced Thermoelectric Performance.

Oxide thermoelectric materials are nontoxic, chemically and thermally stable in oxidizing environments, cost-effective, and comparatively simpler to synthesize. However, thermoelectric oxides exhibit comparatively lower figure of merit () than that of metallic alloy counterparts. In this study, nanoscale texturing and interface engineering were utilized for enhancing the thermoelectric performance of oxide polycrystalline CaCoO materials, which were synthesized using conventional sintering and spark plasma sintering (SPS) techniques.

Ultra-high performance wearable thermoelectric coolers with less materials.

Thermoelectric coolers are attracting significant attention for replacing age-old cooling and refrigeration devices. Localized cooling by wearable thermoelectric coolers will decrease the usage of traditional systems, thereby reducing global warming and providing savings on energy costs. Since human skin as well as ambient air is a poor conductor of heat, wearable thermoelectric coolers operate under huge thermally resistive environment.

All-inorganic nanocrystals as a glue for BiSbTe grains: design of interfaces in mesostructured thermoelectric materials.

Nano- and mesostructuring is widely used in thermoelectric (TE) materials. It introduces numerous interfaces and grain boundaries that scatter phonons and decrease thermal conductivity. A new approach has been developed for the rational design of the interfaces in TE materials by using all-inorganic nanocrystals (NCs) that serve as a "glue" for mesoscopic grains.

Reliable contact fabrication on nanostructured Bi2Te3-based thermoelectric materials.

A cost-effective and reliable Ni-Au contact on nanostructured Bi2Te3-based alloys for a solar thermoelectric generator (STEG) is reported. The use of MPS SAMs creates a strong covalent binding and more nucleation sites with even distribution for electroplating contact electrodes on nanostructured thermoelectric materials. A reliable high-performance flat-panel STEG can be obtained by using this new method.

High-performance flat-panel solar thermoelectric generators with high thermal concentration.

The conversion of sunlight into electricity has been dominated by photovoltaic and solar thermal power generation. Photovoltaic cells are deployed widely, mostly as flat panels, whereas solar thermal electricity generation relying on optical concentrators and mechanical heat engines is only seen in large-scale power plants. Here we demonstrate a promising flat-panel solar thermal to electric power conversion technology based on the Seebeck effect and high thermal concentration, thus enabling wider applications.

Experimental studies on anisotropic thermoelectric properties and structures of n-type Bi2Te2.7Se0.3.

The peak dimensionless thermoelectric figure-of-merit (ZT) of Bi(2)Te(3)-based n-type single crystals is about 0.85 in the ab plane at room temperature, which has not been improved over the last 50 years due to the high thermal conductivity of 1.65 W m(-1) K(-1) even though the power factor is 47 x 10(-4) W m(-1) K(-2).