In a groundbreaking advancement poised to redefine the landscape of energy materials, researchers from Korea Research Institute of Chemical Technology (KRICT) have unveiled an eco-friendly, high-performance thermoelectric (TE) material derived from silver selenide (Ag₂Se). Distinguished by its simple and scalable fabrication process, this novel material offers a sustainable alternative to conventional bismuth telluride-based thermoelectrics, while pushing the boundaries of thermoelectric efficiency and mechanical robustness.
Thermoelectric materials possess the unique capability to directly convert temperature differentials into electrical energy, as well as to induce heating or cooling when subjected to electrical currents. These dual phenomena, known respectively as the Seebeck and Peltier effects, have profound implications across various sectors—ranging from electronic cooling in computing hardware to harnessing waste heat in industrial and automotive processes. Despite their potential, widespread adoption has been hindered by the reliance on rare and environmentally concerning elements, complex manufacturing methodologies, and suboptimal mechanical properties.
The KRICT-led team tackled these persistent challenges head-on by focusing on silver selenide, a compound comprising relatively abundant elements. Their approach capitalizes on a solution-based synthesis process to produce Ag₂Se nanoparticles, which are subsequently enriched with an excess of selenium to form a Se-rich composition designated as Ag₂Se₁.₂. This meticulously engineered ratio pivots the structural and electrical properties of the material, enabling unprecedented thermoelectric performance.
Central to their innovation is the employment of a straightforward heat-treatment protocol at a notably mild temperature of approximately 350°C under ambient pressure conditions. Unlike conventional sintering, which demands extreme temperatures near 1000°C and high-pressure environments, this annealing step exploits the low melting point of selenium. During this phase, selenium transforms into a liquid state, permeating the interstitial spaces among Ag₂Se grains. This liquid-assisted grain growth fosters enhanced grain connectivity and densification, which are pivotal for lowering material porosity and boosting electrical conductivity.
The resultant microstructure of the synthesized Ag₂Se₁.₂ bulk exhibits substantial improvements in both electrical and thermal transport properties. Enhanced grain connectivity minimizes electron scattering, facilitating efficient charge carrier mobility, while the unique grain boundary structures contribute to scattering phonons, effectively suppressing lattice thermal conductivity. These combined effects culminate in an impressive maximum figure of merit (zT) reaching 0.927 at 393 K, a milestone approaching the benchmark set by commercial Bi₂Te₃-based materials.
Beyond thermoelectric efficiency, mechanical integrity remains a critical criterion for practical applications, especially in devices subjected to thermal cycling and mechanical stress. Impressively, the new material demonstrates more than a twofold increase in compressive strength and Young’s modulus compared to its predecessors. This newfound robustness underpins its suitability for integration into complex device geometries, including flexible and curved thermoelectric modules, expanding the horizon for wearable and portable energy-harvesting electronics.
The eco-friendly nature of the fabrication process is underscored by the elimination of rare, toxic elements and the circumvention of energy-intensive manufacturing steps. This aligns with the growing imperative to develop sustainable technologies that mitigate environmental impact while delivering high performance. The ambient pressure and relatively low-temperature annealing not only reduce production costs but also open pathways for scalable industrial adoption.
Potential applications of this high-performance Ag₂Se₁.₂ thermoelectric material span a broad spectrum. It is ideally suited for small-scale power generation systems that capitalize on waste heat from industrial plants, data centers, and concentrated solar thermal setups. Furthermore, its mechanical flexibility and stability offer promising prospects for wearable Internet of Things (IoT) devices and healthcare sensors, which require reliable and compact power sources capable of harvesting body heat or environmental temperature differentials.
This research represents a paradigm shift in thermoelectric material development, demonstrating that high performance need not be sacrificed for simplicity and environmental responsibility. The work of Dr. Young Hun Kang and colleagues exemplifies how leveraging fundamental material properties, such as phase transformations of selenium, can yield transformative results. Their strategy circumvents the customary reliance on complex doping or alloying while achieving near-commercial performance metrics.
Published in Advanced Composites and Hybrid Materials, this study marks a significant milestone in the quest for sustainable and efficient energy conversion technologies. The research community anticipates that this facile and scalable fabrication method will inspire subsequent innovations in thermoelectric materials and advance their commercialization.
Looking ahead, the translation of this technology from laboratory to market could drastically enhance energy efficiency across multiple sectors by enabling effective recovery of waste heat and improving thermal management. Collaboration between academia, industry, and government will be essential to refine processing techniques, optimize device integration, and establish robust standards for widespread application. This breakthrough certainly shines a hopeful light on the future of green energy technologies.
Subject of Research: Thermoelectric materials and material synthesis techniques
Article Title: Facile and scalable strategy for fabricating dense bulk Ag2Se as a highperformance thermoelectric material
News Publication Date: 26-Jan-2026
Web References: http://dx.doi.org/10.1007/s42114-026-01621-0
Image Credits: Korea Research Institute of Chemical Technology (KRICT)
Keywords
Thermoelectric materials, silver selenide, Ag₂Se, Seebeck effect, Peltier effect, energy conversion, waste heat recovery, solution-based synthesis, liquid phase annealing, mechanical robustness, eco-friendly fabrication, high-performance thermoelectrics
