Abstract
The ternary chalcopyrite AgInSe2 has emerged as a promising n-type thermoelectric material with ultralow lattice thermal conductivity. We report the thermoelectric transport properties of sodium-doped Ag1-xIn1+xSe2 using an effective mass model. Temperature-dependent Hall coefficient measurements pave the way to understand the thermal activation behavior of carriers and the corresponding carrier scattering mechanisms. A Pisarenko plot shows that a single parabolic band model can accurately describe the transport behavior witnessed in the Seebeck coefficient and Hall carrier concentration in most samples. Furthermore, the lattice thermal conductivity of the doped samples approaches the theoretical minimum at high temperature, which is mainly due to the decrease of sound velocity. The intrinsically ultralow lattice thermal conductivity of AgInSe2 can be attributed in part to several low-frequency optical phonon modes and strong acoustic-optical phonon hybridization due to an avoided crossing feature in our calculated phonon dispersions. With enhanced power factor arising from the optimization of carrier concentration and depressed lattice thermal conductivity, a maximum figure-of-merit zT of 0.74 was achieved for x = 0.01 with 1 mol % Na sample at 800 K, which doubles that of the pristine sample. The quality factor analysis implies that there is still much room for further improving their thermoelectric performance.
Original language | English (US) |
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Pages (from-to) | 8182-8190 |
Number of pages | 9 |
Journal | Chemistry of Materials |
Volume | 31 |
Issue number | 19 |
DOIs | |
State | Published - Oct 8 2019 |
Funding
The authors would like to acknowledge the financial support from the National Science Foundation of China (U1532128 and 11804023), China Postdoctoral Science Foundation (No. 2018M641205), and the National Science Foundation (NSF) of USA DMR program grant no. 1729487. N.Z.K. and J.M.R. were supported by the NSF (DMR-1454688). We also thank Lei Hu and Kazuki Imasato for helping with this project. Y.Z. acknowledges the financial support of China Scholarship Council (CSC) for studying abroad. N.Z.K. thanks Danilo Puggioni and Daniel Hickox-Young for helpful discussions.
ASJC Scopus subject areas
- General Chemistry
- General Chemical Engineering
- Materials Chemistry