About Thermal Energy Materials Group
In the 20th century mankind has achieved unprecedented control over the electron, spin, photon, however one of the most important scientific challenges for the 21st century is how to achieve a high degree of control over phonons, or rather thermal energy.
Our group is mainly involved in research on development of cutting edge thermoelectric materials and also fundamental understanding, measurement technology, and control over thermal transport. We are also involved in developing thermoelectric devices which can be used to autonomously power innumerable IoT sensors, and modules for realizing energy saving and contributing to carbon neutral goals, and for cooling.
Specialized Research Field
1.Development of novel thermoelectric materials
For thermoelectric material research, we are developing novel enhancement principles based on phonon engineering, and also Seebeck enhancement, which can respectively, overcome the conventional tradeoffs between the individual thermoelectric properties. For the former, for example, we have discovered that selective phonon scattering from nano-micropores can enable simultaneous high electrical conductivity and low thermal conductivity, leading to discovery of a high performance rare-earth free material. For the latter, we have discovered how to utilize magnetism to enhance thermoelectric properties, and have been pioneering the new field of magnetic semiconductor thermoelectric materials. We have demonstrated new principles to enhance the Seebeck effect, through interaction between magnetic moments and electrical carriers, and also spin fluctuation, Anderson localization, for example.
Additionally, by utilizing electron scattering between bands, we have enhanced metal materials that typically have a small Seebeck effect, pioneering a new field of high-performance "metal thermoelectric materials." On the other hand, by utilizing grain boundary interface control and electron delocalization effects, we have also succeeded in enhancing electron mobility in thermoelectric materials.
In other approaches, we have also been carrying out research on band engineering, defect engineering, material informatics, AI, chemical bond engineering, nanocomposites to control thermal and electrical properties, inorganic-organic hybrids, utilization of grain boundaries and interfaces, to develop novel high-performance thermoelectric materials.
A notable example of these efforts is the successful development of abundant, high-performance thermoelectric materials that can surpass the rare bismuth telluride, which has reigned as champion for over half a century.
2.Development of novel electrode materials and thermoelectric power generation devices
We have also developed novel principle of active electrodes compatible to the new high-performance materials, as well as powerful device design techniques such as an AI neural network that enables performance prediction of thermoelectric devices 10,000 times faster than conventional finite element methods.]
We are also developing various implementation formats of thermoelectric power generation devices such as bulk, flexible, and thin-film types for practical applications such as IoT environmental energy harvesting power generation, waste heat power generation, topping cycles in thermal power plants, and solid-state cooling that contribute to energy saving and carbon neutrality.
3. Development of measurement technology for thermal transport, and thermoelectric device development
We have developed an original focused picosecond thermoreflectance apparatus, and have been successfully measuring the cross-plane and in-plane thermal diffusivity of thin films, and evaluation of interface thermal resistance. We have also been able to evaluate the site-selective thermal conductivity of small size crystals, for example.
We have also laid out the best practices for accurate evaluation methods for thermoelectric power generation devices and thermoelectric research.
４、Synthesis of novel inorganic materials and properties development
We have been utilizing the particular network structures (e.g. atomic cluster and 2D atomic nets) and structure-property relations of high temperature ceramic materials such as borides to find new functional materials.
We have also been carrying out multi-faceted research on inorganic materials such as novel oxides, silicides, nitrides, chalcogenides (sulfides, selenides, tellurides).
グループメンバー
Takao MORI
Deputy Director of MANA
Field Director of Nanomaterials Field
Group Leader
