Thermoelectric generators harness the Seebeck effect, converting temperature gradients directly into electrical power without moving parts or fuel consumption. Despite decades of research enhancing material properties to boost thermoelectric performance, practical device efficiencies have struggled under real-world conditions. This discrepancy arises largely because device geometry significantly influences heat transfer pathways, electrical resistance distribution, and the impact of interface contact resistances—factors that interplay in complex ways to dictate overall system efficiency. Historically, TEG designs have relied heavily on human intuition, guided by classical geometric constraints such as simple rectangular shapes that facilitate fabrication but limit performance.

Recognizing these limitations, the research team deployed topology optimization, a computational strategy that enables the design of three-dimensional structures by iteratively refining shapes to maximize a specified objective—in this case, power-generation efficiency—subject to real-world thermal and electrical boundary conditions. Unlike conventional optimization methods, topology optimization does not require predefining the shape; instead, it explores vast design spaces unrestricted by preconceived notions, allowing the computer to “invent” novel geometries that human designers might never visualize.

The computational analyses revealed unconventional geometries, including asymmetric hourglass and I-shaped configurations, which strategically guide heat flow to enhance the temperature difference maintained across the thermoelectric module. By engineering these tailored pathways, heat is concentrated in a manner that optimizes the conversion efficiency while simultaneously mitigating electrical losses through minimized resistance and reduced contact degradations. These geometries cannot be realized with traditional design techniques and underscore the power of computational creativity in engineering innovation.

To validate their designs experimentally, the team utilized advanced additive manufacturing technologies—specifically 3D printing—to fabricate the complex structures predicted by the optimization algorithms. This capability to translate highly irregular and intricate topologies from virtual models to physical devices marks a significant milestone for thermoelectric devices, which have traditionally been constrained by fabrication challenges. Subsequent performance testing demonstrated an astonishing 8.2-fold increase in power-generation efficiency compared to a benchmark rectangular TEG, corroborating the computational predictions with remarkable fidelity.

The implications of this research are profound for the future of sustainable energy systems. Waste heat, abundantly produced in automotive exhausts, heavy industrial processes, semiconductor manufacturing, and even from the human body, has long been an untapped resource. The ability to convert this otherwise lost thermal energy into usable electrical power promises significant advances in energy efficiency and carbon footprint reduction. The geometry-driven optimization approach introduced here suggests that further leaps in thermoelectric technology will arise not only from better materials but from smarter, tailored designs optimally tuned to their operating environments.

Professor Jae Sung Son, leading the study from POSTECH’s Department of Chemical Engineering, highlighted that the research transcends material-centric improvements and pioneers a holistic design framework that integrates thermal, electrical, and geometric factors. This approach holds the potential to revolutionize the way thermoelectric devices are conceived and deployed, making them far more practical and efficient for widespread applications in energy harvesting and power systems.

Complementing this perspective, Professor Hayoung Chung of UNIST emphasized the role of artificial intelligence and machine learning integration, envisioning a future where device structures evolve dynamically from input conditions without manual intervention or extensive trial-and-error iterations. Such convergence of computational optimization and AI could accelerate the design cycle, foster innovation, and expand the applicability of thermoelectric generators across diverse fields.

Beyond the immediate application to energy harvesting, the methodology developed here demonstrates a broader principle relevant to materials engineering and device fabrication: by embracing topology optimization combined with additive manufacturing, engineers can unlock new performance regimes previously unattainable due to design and manufacturing constraints. This synergy opens new frontiers in engineering, from thermal management to electronics, where complex geometries provide tailored functional advantages.

The research was underpinned by significant support from the Korean National Research Foundation (NRF) through the Mid-Career Researcher Program and the Nano & Material Technology Development Program, funded by the Ministry of Science and ICT. Such funding underscores the strategic importance of advancing alternative and renewable energy technologies to address global energy challenges.

This innovative work not only lays the foundation for next-generation thermoelectric devices but also exemplifies how computational sciences and cutting-edge manufacturing can jointly propel sustainable technologies forward. As industries and societies strive for improved energy efficiency and reduced emissions, breakthroughs like this set a powerful precedent for the future of thermal energy harvesting and beyond.

As the research community digests these findings, the prospects for integrating topology-optimized thermoelectric generators into practical systems are promising. Whether embedded in automotive heat recovery units, industrial waste heat systems, or portable power generators, these newly conceptualized designs might redefine energy efficiency standards and fuel the transition towards smarter, greener energy solutions worldwide.

Subject of Research: Topology optimization for thermoelectric generator design to maximize power efficiency through advanced 3D geometries and additive manufacturing.

Article Title: Topology optimization of thermoelectric generator for maximum power efficiency

News Publication Date: 19-Feb-2026

Web References: DOI link

Image Credits: POSTECH

Keywords: Thermoelectricity, Electrical power, Energy harvesting, Power systems, Topology, Fabrication, Additive manufacturing, Alternative energy, Renewable energy

The essence of this novel thermoelectric generator lies in its ingenious use of kirigami, a Japanese paper art involving strategic cutting to transform flat sheets into expandable, three-dimensional structures. Unlike previous rigid thermoelectric devices, the application of kirigami enables the creation of a pop-up mechanism that expands and conforms seamlessly to non-planar and dynamic surfaces. This adaptive quality marks a significant improvement over traditional devices, which often suffer efficiency losses due to poor thermal interface contact and mechanical deformation when subjected to stretching.

At the core of this device is the synergy between mechanical flexibility and efficient thermoelectric performance. Thermoelectric generators fundamentally rely on the Seebeck effect, where a temperature gradient across materials generates a voltage difference, enabling the conversion of heat into electricity. Achieving high stretchability while maintaining this thermoelectric performance has been a notorious hurdle because mechanical strain often disrupts electrical pathways and degrades material properties. The kirigami-inspired architecture elegantly circumvents this, providing predefined stretch zones that mitigate strain on the active thermoelectric components.

The pop-up structure, revealed upon mechanical deformation, is meticulously engineered to maximize both thermal contact and mechanical resilience. By strategically patterning cuts and folds within the thermoelectric layer, the generator expands in three dimensions, allowing it to envelop complex geometries such as curved human skin or irregular industrial surfaces. This geometric adaptability not only enhances wearer comfort and device longevity in wearable applications but also improves heat harvesting efficiency by optimizing the thermal interface between the device and heat source.

Conformal thermal interfaces represent another critical advance exhibited by this technology. Traditional flat thermoelectric devices struggle to maintain intimate thermal contact with rough or moving surfaces, often causing thermal resistance and consequently reducing energy conversion efficiency. The kirigami pop-up design dynamically adjusts its contour to the surface topology, minimizing interfacial gaps that lead to thermal losses. This intimate contact promotes efficient heat flow from the heat source into the thermoelectric elements, heightening the overall power output.

Material selection remains paramount in this achievement. The research team employed advanced thin-film thermoelectric materials with high Seebeck coefficients, low thermal conductivity, and adequate electrical conductivity, ensuring robust energy conversion even under mechanical deformation. The implementation of stretchable substrates and conductive interconnections further enhances device durability and maintains electrical continuity throughout repetitive deformation cycles.

Another dimension of this work tackles the integration challenge characteristic of flexible thermoelectric systems. Conventional devices are often bulky or involve complex fabrication steps that hamper scalability and widespread adoption. The kirigami pop-up generator, by contrast, is fabricated through cost-effective processes adaptable to large-area manufacturing techniques. This aspect paves the way for scalable production and represents a crucial stride toward commercial applications ranging from wearable electronics to industrial waste heat recovery.

The potential applications for this transformative technology extend broadly. In wearable health monitors, for example, the stretchable thermoelectric generator could supply power by harnessing body heat without impeding natural movements or comfort. Such self-powered wearables could revolutionize medical diagnostics and fitness tracking by obviating the need for batteries. Industrially, embedding these conformal generators onto irregular machinery surfaces could recover and convert otherwise wasted thermal energy into auxiliary power, contributing to sustainable energy ecosystems.

This research also highlights remarkable durability under mechanical stress. Experimental data demonstrate that the device retains stable energy conversion performance even after multiple cycles of stretching and folding, underscoring its robustness for real-world conditions. The kirigami pattern inherently distributes strain uniformly, preventing localized damage that often plagues flexible electronic devices, thereby extending operational lifespan.

Thermal management is another inherent advantage of this innovation. The 3D pop-up structure naturally facilitates heat dissipation due to its increased surface area and air flow within folded segments, which can mitigate overheating issues common in tightly packed thermoelectric systems. This passive cooling effect can ensure consistent performance over prolonged operation, which is critical for both wearable and industrial environments.

Moreover, by combining mechanical adaptability and efficient thermal interfacing, this thermoelectric generator sets a new benchmark for multifunctional flexible electronics. It not only harvests energy but can also be integrated into sensor platforms that demand conformal and robust components. The versatility of the kirigami design opens avenues for smart skins and next-generation electronic textiles, potentially enabling devices that adapt in real-time to dynamic environmental conditions.

From a broader scientific perspective, the application of kirigami principles to thermoelectric energy harvesting introduces a paradigm shift, blending artful geometry with cutting-edge material science. This interdisciplinary approach underscores the importance of novel structural engineering concepts in overcoming physical limitations in flexible electronic devices, illustrating how biomimicry and cultural art forms can inspire high-tech solutions.

The implications of this development are far-reaching, particularly as the global push towards sustainable, decentralized energy solutions intensifies. By providing a flexible, efficient, and scalable method for converting low-grade heat into usable electrical power, the kirigami pop-up thermoelectric generator aligns perfectly with green technology initiatives aimed at enhancing energy autonomy and reducing fossil fuel dependence.

In conclusion, this pioneering work merges the elegance of kirigami design with state-of-the-art thermoelectric materials to produce a highly stretchable, conformal thermoelectric generator capable of efficient heat energy harvesting across complex surfaces. Its impressive mechanical resilience, scalable fabrication, and improved thermal interfaces mark it as a promising candidate for powering future flexible electronics and energy scavenging systems, potentially transforming how we harness and utilize ambient heat energy.

As energy demands evolve and the Internet of Things becomes increasingly pervasive, devices such as this kirigami thermoelectric generator will be pivotal in enabling sustainable, self-sufficient electronics. The research exemplifies how cross-disciplinary innovation can solve entrenched problems in energy technology and sets an exciting precedent for future explorations into adaptable, multifunctional electronic materials.

Subject of Research: Flexible and stretchable thermoelectric energy harvesting devices using kirigami-inspired design.

Article Title: Pop-up kirigami thermoelectric generator with high stretchability and conformal thermal interfaces.

Article References:
Terashima, S., Ohnishi, M., Shiomi, J. et al. Pop-up kirigami thermoelectric generator with high stretchability and conformal thermal interfaces. npj Flex Electron 9, 105 (2025). https://doi.org/10.1038/s41528-025-00454-z

Image Credits: AI Generated

Addressing this critical bottleneck, researchers at the University of Rochester’s Institute of Optics have developed a groundbreaking approach that radically enhances STEG performance. Their pioneering research, recently published in Light: Science and Applications, introduces an innovative integration of femtosecond laser-based spectral engineering alongside sophisticated thermal management techniques. This triad of strategies culminated in a STEG device capable of generating electrical power with 15 times the efficiency of prior models, signaling a transformative leap forward in renewable energy technology.

Central to this advancement is the adoption of a novel black metal technology cultivated within Chunlei Guo’s laboratory. By subjecting tungsten metal surfaces to ultrafast femtosecond laser pulses, the team precisely etched nanoscale structures that fundamentally alter the material’s optical properties. This meticulous surface engineering enhances the material’s absorption of solar wavelengths, maximizing the capture of incident sunlight while suppressing thermal emissions at non-solar wavelengths. Essentially, the engineered black metal acts as a highly selective solar absorber, efficiently converting sunlight into thermal energy localized on the hot side of the STEG, thereby amplifying the available thermal gradient.

Beyond the solar absorber itself, the researchers innovated with thermal management to sustain and exploit this enhanced energy capture. Drawing inspiration from agricultural greenhouses, they encapsulated the black metal surface beneath a transparent plastic layer. This “mini greenhouse” design effectively minimizes heat losses driven by convection and conduction, trapping the absorbed solar heat and substantially elevating the hot side temperature. By intensifying this thermal reservoir, the temperature differential across the STEG is significantly increased, directly boosting the electric power output due to the Seebeck effect’s temperature dependence.

Complementing the enhancements on the hot side, the cold side of the STEG was also optimized to refine overall device efficiency. Applying femtosecond laser pulses to aluminum surfaces, the researchers fabricated micro- and nanoscale textures designed to amplify heat dissipation via both radiative and convective mechanisms. This laser-induced structuring effectively doubles the cooling performance of standard aluminum heat sinks, ensuring the cold side remains efficiently cooled and preserving the critical temperature gradient across the semiconductor materials sandwiched within.

Interestingly, the research team deliberately chose not to modify the semiconductor materials at the STEG core, an area where many prior efforts have concentrated. Instead, by focusing on the engineering of the thermal interfaces—the hot and cold sides—they demonstrated that dramatic efficiency improvements can be realized through spectral and thermal control alone. This paradigm shift in design philosophy opens new avenues for device optimization that are compatible with existing, well-developed semiconductor technologies, potentially simplifying manufacturing and lowering costs.

To validate the practical implications of their design, Guo and colleagues demonstrated that their STEG could drive light-emitting diodes (LEDs) with markedly improved performance compared to conventional thermoelectric generators. This validation not only underscores the technical merit of their approach but also highlights its applicability in real-world power generation scenarios. The scalability and robustness of their method suggest compelling potential uses, including powering wireless sensor networks integral to the Internet of Things, energizing wearable devices, and enabling off-grid renewable power supplies for remote or rural communities where access to reliable electricity remains a challenge.

The innovative use of femtosecond lasers in this research exemplifies cutting-edge optical engineering and materials science synergy. Ultrafast laser pulses offer precise control over material morphology at nanometer scales, enabling the tailoring of optical and thermal properties in ways unattainable by conventional fabrication methods. This laser-based surface modification facilitates the creation of highly selective solar absorbers and enhanced thermal emissive surfaces without altering bulk material properties, a crucial advantage for industrial scalability and material stability.

Moreover, the approach of enhancing solar thermoelectric generators through spectral engineering and thermal management aligns well with global sustainability goals. Thermoelectric devices can leverage diverse heat sources, and improving their conversion efficiency directly decreases dependency on fossil fuels while offering avenues for clean, decentralized power generation. The potential environmental and economic impacts of such high-efficiency STEGs could be profound, extending from urban to off-grid applications and contributing to a more resilient and sustainable energy infrastructure.

This research received support from the National Science Foundation, FuzeHub, and the Goergen Institute for Data Science and Artificial Intelligence, illustrating the multidisciplinary collaboration necessary to tackle complex energy challenges. The successful integration of femtosecond laser technology, thermal physics, and materials engineering in this project epitomizes the kind of innovative thinking that drives transformative advances in renewable energy technologies.

Looking forward, the principles demonstrated in this study could inspire further investigations into hybrid devices combining thermoelectric and photovoltaic functionalities or the development of adaptive systems that dynamically optimize spectral and thermal responses based on environmental conditions. The marriage of ultrafast laser fabrication techniques with thermoelectric materials science opens a fertile landscape for tailored energy harvesting solutions, potentially revolutionizing how we convert and utilize solar and thermal energy.

In summary, the University of Rochester team’s achievement in elevating STEG performance by a factor of fifteen through femtosecond-laser spectral engineering and refined thermal management represents a watershed moment in the development of renewable energy technologies. This leap not only underscores the untapped potential within thermoelectric systems but also exemplifies how interdisciplinary innovation at the nexus of optics, materials science, and thermal engineering can unlock new frontiers in energy harvesting—heralding a future where clean, efficient, and versatile solar energy devices become integral components of the global energy landscape.

Subject of Research: Solar thermoelectric generators, femtosecond laser spectral engineering, thermal management, renewable energy technology.

Article Title: 15-Fold increase in solar thermoelectric generator performance through femtosecond-laser spectral engineering and thermal management

News Publication Date: 12-Aug-2025

Web References:

• https://www.nature.com/articles/s41377-025-01916-9
• http://dx.doi.org/10.1038/s41377-025-01916-9
• https://www.rochester.edu/newscenter/lasers-etch-a-perfect-solar-energy-absorber-414902/

Image Credits: University of Rochester photo / J. Adam Fenster

Keywords

Thermoelectricity, Physics, Condensed matter physics, Physical sciences, Applied optics, Applied physics, Laser systems, Lasers, Photovoltaics, Electronics, Engineering, Solar energy, Alternative energy, Energy resources

In the heart of this breakthrough lies a team led by Professor Andrej Pustogow at the Institute of Solid State Physics. Their work centers around reimagining the classical understanding of thermoelectricity by exploring metallic materials traditionally overlooked in this field. "Despite decades of optimism and research into semiconductors for thermoelectric applications, the fundamental performance ceiling has remained stubbornly consistent," Pustogow notes. "Our approach challenges that status quo by focusing on metallic systems, which were widely deemed unsuitable because of their balanced positive and negative charge carriers cancelling out voltage generation." This paradigm shift has allowed them to unlock thermoelectric potential in previously uncharted metallic compounds.

The cornerstone of thermoelectricity rests on how charge carriers—namely electrons and holes—move within a material under a thermal gradient. In semiconductors, where predominantly one type of charge carrier prevails, heating one side causes those charges to diffuse differently than on the cooler side, creating a voltage difference. Metals, conversely, contain both positive and negative carriers that tend to neutralize each other’s thermally induced movements, resulting in negligible net voltage. The core challenge, then, is to decouple this balancing act by disrupting the synchronized flow of oppositely charged carriers.

Pustogow’s team has ingeniously conceptualized the charge carriers’ transport like vehicles on a multilane highway—each lane representing a carrier type moving in parallel. By introducing deliberate “traffic jams” on one lane, positive and negative carriers can be made to traverse at differing speeds. This traffic congestion analogy maps to real physical mechanisms where certain charge carriers face localized immobilization due to engineered defects or intrinsic material properties, thereby skewing the balance and generating substantial voltages even in metals.

One realization of this principle emerged with nickel-gold alloys studied by the researchers in 2023, where the presence of gold atoms introduced specific scattering centers that hindered positive charges more than negative ones. Although effective, the cost of gold posed a barrier to commercial viability, prompting the search for more economical alternatives. The team’s subsequent discovery of nickel-indium compounds shows similar promise at a fraction of the expense, marking a critical step toward scalable thermoelectric technologies.

A particularly fascinating facet of this research is the exploitation of a geometric pattern known as the kagome lattice—a configuration reminiscent of woven Japanese bamboo baskets featuring an interlaced arrangement of triangles and hexagons. This “geometrical frustration” creates unusual electronic properties, including highly localized and immobilized charges within the lattice’s motifs. Such spatial charge confinement generates an asymmetric mobility landscape for electrons and holes, which is ideally suited to enhancing thermoelectric performance.

The kagome lattice’s unique quantum mechanical effects cause one subset of carriers to become effectively trapped, disrupting the natural compensation between positive and negative charges. In the case of nickel-indium kagome metals, the negative charges maintain free flow while positive charges face significant mobility reduction. This imbalance leads to remarkably high Seebeck coefficients, surpassing those of traditional bismuth telluride thermoelectrics widely used today. Significantly, this effect manifests at room temperature, making these materials practical for real-world applications.

Beyond the geometry, the research delves into the complex interplay of topology and electronic band structure—fields rapidly gaining traction in condensed matter physics. In particular, “flat bands” induced by the kagome architecture lead to highly localized electronic states with minimized kinetic energy, favoring strong electronic correlations that underlie the traffic jam phenomenon. By tuning these topological band features, the TU Wien team has demonstrated a novel mechanism to control and enhance thermoelectric responses in metals, fundamentally distinct from traditional semiconductor approaches.

Optimizing these metallic thermoelectrics requires balancing several competing factors, including electrical conductivity, thermal conductivity, and the Seebeck coefficient—a triad collectively described by the dimensionless figure of merit, ZT. The team’s experiments reveal that geometrically frustrated kagome metals achieve a synergistic enhancement of these parameters, pushing ZT values to unprecedented levels for metallic systems. This opens the door for efficient waste heat recovery technologies and compact power sources that were previously thought unattainable with metal-based materials.

What this research exemplifies is the transformative potential of combining intricate quantum phenomena with materials engineering to address classic challenges in energy science. By moving away from the semiconductor-centric view and embracing metallic systems with engineered band structures and frustration effects, thermoelectric technology gains a fresh trajectory. As Prof. Pustogow highlights, “We are now harnessing the power of topology, geometry, and strong electron interactions to realize thermoelectrics that were simply unimaginable a decade ago.”

The implications are far-reaching. Widespread deployment of high-efficiency thermoelectrics could revolutionize industries by harvesting low-grade waste heat from engines, industrial processes, and even body heat, converting it directly into electricity without moving parts or emissions. This aligns with global sustainability goals and the push for decentralized renewable energy solutions. Moreover, the scalability and relative abundance of the constituent elements in kagome metals promise economical manufacturing routes.

Looking ahead, ongoing efforts by the TU Wien group focus on fine-tuning the synthesis methods to optimize the purity, crystal quality, and defect landscape, all critical to maximizing thermoelectric performance. Parallel theoretical studies continue to unravel the intricate quantum mechanics governing kagome lattices, laying the groundwork for designing materials with tailor-made properties. The convergence of these experimental and computational advances signals an exciting future where metallic thermoelectrics become a commercial reality.

In essence, this breakthrough marks a pivotal moment in thermoelectrics research, challenging long-standing dogmas and unveiling metallic compounds as powerful candidates for energy conversion. By marrying classical concepts with cutting-edge quantum material science, the team at TU Wien has not only “struck gold” metaphorically but has also pointed the way toward a cleaner, more efficient energy future powered by the subtle dance of electrons within kagome lattices.

Subject of Research: Not applicable

Article Title: Topological Flat-Band-Driven Metallic Thermoelectricity

News Publication Date: 14-May-2025

Web References: 10.1103/PhysRevX.15.021054

Image Credits: TU Wien

Keywords

Thermoelectricity, Seebeck Effect, Kagome Lattice, Metallic Thermoelectrics, Geometrical Frustration, Topological Flat Bands, Nickel-Indium Alloys, Charge Carrier Mobility, Waste Heat Recovery, Quantum Materials, Energy Conversion, Solid State Physics