Research team develops key n-type thermoelectric semiconductor technology to recycle waste heat

A research team develops a bismuth telluride (Bi-Te)-based thermoelectric material with artificially formed atomic-scale defects and proposes a solution to improve its properties to harness wasted thermal energy. did. This is a semiconductor technology applied to thermoelectric power generation devices that generate electricity by reusing waste heat below 200℃ emitted from industrial and transportation fields such as factories, automobiles, and ship engines. A thermoelectric generator is a combination of p-type and n-type semiconductors that reversibly converts temperature differences into electrical energy and vice versa.

Previous research has focused on improving the properties of p-type thermoelectric materials composed of bismuth (Bi) and tellurium (Te). On the other hand, improvements in properties of n-type thermoelectric semiconductors containing selenium (Se) have been slow due to the difficulty of controlling their composition and microstructure, which has been pointed out as an obstacle to the practical application of thermoelectric technology.

The research team focused on the n-type thermoelectric semiconductor, which determines the performance of thermoelectric generators, and made breakthrough progress that had stalled for decades. The key to this breakthrough lies in doping materials and manufacturing processes. The research is published in the journal ACS Applied Materials & Interfaces.

Doping materials are elements added to improve the conductivity of semiconductors. Recognizing that p-type bismuth telluride using antimony (Sb) as a doping material is likely to achieve optimal performance, the research team decided to replace the commonly used selenium (Se) as a doping material. We have developed an n-type material incorporating antimony (Sb). Doping material for n-type bismuth telluride.

The research team also developed a method to artificially induce “atomic defects” that promote electron generation and “dislocation networks” that scatter the movement of lattice phonons, which are heat transfer media, during the fabrication process of n-type thermoelectric materials. did. It has high electrical conductivity and low thermal conductivity. This technology uses the powder metallurgy route of heating and sintering in a mold, making it easy to produce thermoelectric materials in designed shapes and sizes.

The n-type thermoelectric semiconductor developed using this technology clearly exhibits the thermal and electrical properties required for thermoelectric devices, such as more than doubling electrical conductivity while lowering thermal conductivity. In particular, our research team’s thermoelectric technology boasts excellent energy conversion performance and is easy to combine with materials, so it is expected to be applied to recycling heat at room temperatures of around 200 degrees Celsius, including the heat of the human body.

The thermoelectric generator market is growing at a CAGR of 8.2% and is expected to reach $1.18 billion globally by 2029. The research team is currently developing a thermoelectric power plant in collaboration with Living Care Co., Ltd. In cooperation with Hyundai Motor’s Ulsan Plant, we will conduct basic research on a power generation system that recovers waste heat generated from molds.

Dr. Kim Kyung-tae, who led this research, said, “This research served as a stepping stone to solving the problem of controlling the characteristics of n-type thermoelectric semiconductors, which has been an obstacle in recycling various types of waste heat below 200 degrees Celsius.” said.

“Their importance lies in the development of nanostructured thermoelectric material technology using conventional powder metallurgy techniques to control defects at the atomic level.”