S-Space College of Engineering/Engineering Practice School (공과대학/대학원) Dept. of Chemical and Biological Engineering (화학생물공학부) Journal Papers (저널논문_화학생물공학부)
Enhancing p-Type Thermoelectric Performances of Polycrystalline SnSe via Tuning Phase Transition Temperature
- Lee, Yong Kyu; Ahn, Kyunghan; Cha, Joonil; Zhou, Chongjian; Kim, Hyo Seok; Choi, Garam; Chae, Sue In; Park, Jae-Hyuk; Cho, Sung-Pyo; Park, Sang Hyun; Sung, Yung-Eun; Lee, Won Bo; Hyeon, Taeghwan; Chung, In
- Issue Date
- Journal of the American Chemical Society, Vol.139 No.31, pp.10887-10896
- SnSe emerges as a new class of thermoelectric materials since the recent discovery of an ultrahigh thermoelectric figure of merit in its single crystals. Achieving such performance in the polycrystalline counterpart is still challenging and requires fundamental understandings of its electrical and thermal transport properties as well as structural chemistry. Here we demonstrate a new strategy of improving conversion efficiency of bulk polycrystalline SnSe thermoelethics. We show that PbSe alloying decreases the transition temperature between Pnma and Cmcm phases and thereby can serve as a means of controlling its onset temperature. Along with 1% Na doping, delicate control of the alloying fraction markedly enhances electrical conductivity by earlier initiation of bipolar conduction while reducing lattice thermal conductivity by alloy and point defect scattering simultaneously. As a result, a remarkably high peak ZT of similar to 1.2 at 773 K as well as average ZT of similar to 0.5 from RT to 773 K is achieved for Na-0.01(Sn1-xPbx)(0.99)Se. Surprisingly, spherical-aberration corrected scanning transmission electron microscopic studies reveal that NaySn1-xPbxSe (0 < x <= 0.2; y = 0, 0.01) alloys spontaneously form nanoscale particles with a typical size of similar to 5-10 nm embedded inside the bulk matrix, rather than solid solutions as previously believed. This unexpected feature results in further reduction in their lattice thermal conductivity.
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- College of Engineering/Engineering Practice School (공과대학/대학원)Dept. of Chemical and Biological Engineering (화학생물공학부)Journal Papers (저널논문_화학생물공학부)
College of Engineering/Engineering Practice School (공과대학/대학원)Dept. of Chemical and Biological Engineering (화학생물공학부)Chemical Convergence for Energy and Environment (에너지환경 화학융합기술전공)Journal Papers (저널논문_에너지환경 화학융합기술전공)