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  • 09월 20일 16시 이후 : 초록수정 불가능, 일정확인 및 검색만 가능

제126회 대한화학회 학술발표회 및 총회 Realizing Exceptionally High Average Power Factor and Thermoelectric Figure of Merit in n-type PbSe by Dual Incorporation of Cu and Te

2020년 9월 3일 17시 03분 11초
MAT.P-490 이곳을 클릭하시면 발표코드에 대한 설명을 보실 수 있습니다.
10월 21일(수) 17:30~18:00
Materials Chemistry
저자 및
Zhou Chongjian, Chung In1,*
Chemical and biological engineering, Seoul National University, Korea
1School of Chemical & Biological Engineering, Seoul National University, Korea
Simultaneously improving power factor and ZT values has been one of the hardest challenges in thermoelectrics regardless of systems of interest. Here we report that new n-type thermoelectric system CuxPbSe0.99Te0.01 (x = 0.0025, 0.004, and 0.005) exhibiting record-high average ZT of ~1.3 from 400 to 773 K ever reported for any n-type polycrystalline materials including the state-of-the-art PbTe. We concurrently alloy Te to the PbSe lattice and introduce excess Cu to its interstitial voids. Atom probe tomography analysis confirmed a strong attraction between interstitial Cu and Te atoms in the lattice. It increased carrier concentration without damaging its mobility and the consequently improved electrical conductivity. This interaction also increases effective mass of electron in the conduction band according to the first principle calculation, raising the magnitude of Seebeck coefficient without diminishing electrical conductivity. Resultantly, Cu0.005PbSe0.99Te0.01 attains exceptionally high average power factor of ~27 μW cm−1 K−2 from 400 to 773 K with a maximum of ~30 μW cm−1 K−2 at 300 K, which is the highest among all PbSe-based materials. Its ~23 μW cm−1 K−2 at 773 K is even higher than ~21 μW cm−1 K−2 of the state-of-the-art n-type PbTe. Interstitial Cu atoms induce the formation of coherent nanostructures. They are highly mobile under electron beam irradiation accompanied by local heating, consequently displacing Pb atoms from the ideal octahedral center and severely distorting the local microstructure. This significantly depresses lattice thermal conductivity to ~0.2 Wm−1 K−1 at 773 K below the theoretical lower bound. The multiple effects of the dual incorporation of Cu and Te synergistically boosts a ZT of Cu0.005PbSe0.99Te0.01 to ~1.7 at 773 K.