– Realization of thermoelectric figure of merit ZT = 1.0 by controlling the crystal structure in the nanometer range –
Researchers) Priyanka JOOD, Researcher, and OHTA Michihiro, Senior Researcher, Thermoelectrics and Thermal Management Team, Global Zero Emission Research Center
- Development of a thermoelectric conversion material (n-type) consisting of silver selenide (Ag2Se), which exhibits excellent performance at near-room temperature
- Achievement of a thermoelectric figure of merit ZT = 1.0, which is a guide for practical use, over the range from room temperature to 100 °C, by stabilization of the crystal structure, etc.
- Contribution to development of an IoT society by realizing stand-alone power supply by thermoelectric power generation and local cooling by thermoelectric cooling, etc.
Scanning transmission electron microscope images of the developed Ag2Se thermoelectric conversion material and thermoelectric figure of merit ZT
(a) Low-ZT sample with a slight amount of monoclinic crystal structures, (b) High-ZT sample in which formation of monoclinic crystal structures is suppressed by a slight excess of Se
Thermoelectric conversion, which enables conversion between heat and electricity, is expected to be applied to thermoelectric power generation devices that can convert unused thermal energy into useful electricity, and is also used in thermoelectric cooling devices that enable precise cooling using electricity. With the recent, rapid advancement of smart technologies such as IoT, development of stand-alone power supplies for electronic devices and thermal control for electronic devices are becoming an issue, and expectations are increasing for thermoelectric power generation devices and cooling devices. To achieve the full-scale spread of thermoelectric power generation devices and the further spread of thermoelectric cooling devices, it is essential to increase the efficiency, that is to say improve the thermoelectric figure of merit ZT, of thermoelectric conversion materials that are at the core of thermoelectric conversion technology.
Researchers have developed a n-type thermoelectric conversion material consisting of silver selenide (Ag2Se), which exhibits excellent performance at near-room temperature, as part of the New Energy and Industrial Technology Development Organization's (NEDO) "Research and Development Project for Innovative Thermal Management Materials and Technologies."
The high performance of the developed thermoelectric conversion material is due to stabilization of the crystal structure, which enhances the charge carrier mobility and optimizes the carrier concentration. Use is expected for applications such as stand-alone power supplies that can be used in electronic devices for IoT and local cooling of electrical equipment.