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A research team has developed a bismuth telluride (Bi-Te) based thermoelectric material with artificially formed atomic-scale defects and proposed a solution to improve its properties in order to harness wasted thermal energy. This is a semiconductor technology applied to thermoelectric power generators that generate electricity by recycling waste heat below 200℃ from industrial and transportation sectors such as factories, automobiles, and ship engines. Thermoelectric power generators are a combination of p-type and n-type semiconductors that reversibly convert temperature differences into electrical energy and vice versa.

Until now, research has focused on improving the properties of p-type thermoelectric materials composed of bismuth (Bi) and tellurium (Te). On the other hand, n-type thermoelectric semiconductors containing selenium (Se) have been slow to improve their properties due to the difficulty in controlling the composition and microstructure, which has been pointed out as a hindrance to the commercialization of thermoelectric technology.

The research team focused on n-type thermoelectric semiconductors, which determine the performance of thermoelectric power generators, and made a breakthrough that has been stalled for decades. The key to the breakthrough lies in the doping material and manufacturing process. The study is published in the journal ACS Applied Materials & Interfaces.

Doping materials are elements that are added to improve the electrical conductivity of a semiconductor. Recognizing that p-type bismuth telluride with antimony (Sb) as a doping material are likely to achieve optimal performance, the team developed an n-type material that incorporates antimony (Sb) instead of selenium (Se), which is commonly used as a doping material for n-type bismuth telluride.

Key products developed by the research team (from left: n-type thermoelectric semiconductor powder material—wafer—thermoelectric power generator). Credit: Korea Institute of Materials Science (KIMS)

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