What is it about?
In this paper, we have investigated the thermoelectric behavior of Ag2Se, which shows high-zT near room temperature and, therefore, has the potential to replace Bi2Te3 – the workhorse of the thermoelectric industry for near-room-temperature applications. In this paper, we demonstrate the successful use of an all-room-temperature method of synthesizing very high-density Ag2Se ingots exhibiting high and reproducible zT. Using our method, the highest zT obtained is 0.92 at 370 K. Besides a high value of zT, we show that this high zT value can also be reproduced exactly. This is done by preparing a second sample of the same composition. We found that the zT of our two independently prepared samples is not only high but also overlaps nicely over the whole temperature range.
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Why is it important?
In this paper, we demonstrate the successful use of an all-room-temperature method of synthesizing very high-density Ag2Se ingots exhibiting high and reproducible zT. Using our method, the highest zT obtained is 0.92 at 370 K. Besides a high value of zT, we show that this high zT value can also be reproduced exactly. This is done by preparing a second sample of the same composition. We found that the zT of our two independently prepared samples is not only high but also overlaps nicely over the whole temperature range. Further, by measuring the temperature dependence of carrier concertation and thereupon extracting the temperature-dependent mobilities, we present a clear picture of how the Se off-stoichiometry in Ag2Se (a subject of great interest in recent years for the reasons stated above) affects the carrier transport.
Perspectives
I hope that the work presented in this article will serve as a guide for thermoelectric researchers and industrialists working with room-temperature applications to prepare high-quality samples of Ag2Se. Additionally, it highlights the insights gained from manipulating defects in Ag2Se, which has been a source of confusion for decades due to the drastic variations in its transport properties resulting from even the slightest changes in anion access. Although the work initially encountered frustration when results were not reproducible with high-temperature synthesis, it ended well with the development of a new and innovative synthesis method that produced high-quality and reproducible data.
Navita Jakhar
Indian Institute of Science Education Research Pune
Read the Original
This page is a summary of: Reproducible high thermoelectric figure of merit in Ag2Se, Applied Physics Letters, April 2023, American Institute of Physics,
DOI: 10.1063/5.0143678.
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