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Anomalous Thermoelectricity of Pure ZnO from 3D Continuous Ultrathin Nanoshell Structures

Abstract

ZnO is a potential thermoelectric material because of its non-toxicity, high thermal stability, and relatively high Seebeck coefficient (S) of metal oxides. However, the extremely low figure of merit (zT), which comes from a high thermal conductivity (κ) over 40 W/mK, limits the thermoelectric application of ZnO. In particular, below 500 K, ZnO exhibits a nearly negligible zT (< 10-3), unless a dopant is incorporated into the crystal structure. Here, we propose a new strategy for achieving a reduced κ and a correspondingly increased zT of pure ZnO over a wide temperature range from 333 K to 723 K by forming an ~72 nm thick, 3D continuous ultrathin nanoshell structure. The suppressed κ of the 3D ZnO film is ~3.6 W/mK at 333 K, which is ~38 times lower than that of the blanket ZnO film (3.2 μm thick), which was set as a reference. The experimental zT of the 3D ZnO film is ~0.017 at 333 K, which is the highest value among pure ZnO reported to date and is estimated to increase by ~0.072 at 693 K according to the Debye-Callaway approach. Large-area (~1 in2) fabrication of the 3D ZnO film with high structural uniformity allows the realization of an integrated thermoelectric device, which generates ~60 mV at a temperature difference of 40 K along the in-plane direction.

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Publication details

The article was received on 02 Nov 2017, accepted on 31 Dec 2017 and first published on 02 Jan 2018


Article type: Paper
DOI: 10.1039/C7NR08167G
Citation: Nanoscale, 2018, Accepted Manuscript
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    Anomalous Thermoelectricity of Pure ZnO from 3D Continuous Ultrathin Nanoshell Structures

    K. Kim, J. Park, S. Hong, S. H. Park, S. G. Jeon, C. Ahn, J. Y. Song and S. Jeon, Nanoscale, 2018, Accepted Manuscript , DOI: 10.1039/C7NR08167G

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