Jump to main content
Jump to site search

Issue 4, 2018
Previous Article Next Article

Deep defect level engineering: a strategy of optimizing the carrier concentration for high thermoelectric performance

Author affiliations

Abstract

Thermoelectric properties are heavily dependent on the carrier concentration, and therefore the optimization of carrier concentration plays a central role in achieving high thermoelectric performance. The optimized carrier concentration is highly temperature-dependent and could even possibly vary within one order of magnitude in the temperature range of several hundreds of Kelvin. Practically, however, the traditional doping strategy will only lead to a constant carrier concentration, and thus the thermoelectric performance is only optimized within a limited temperature range. Here, we demonstrate that a temperature-dependent carrier concentration can be realized by simultaneously introducing shallow and deep defect levels. In this work, iodine (I) and indium (In) are co-doped in PbTe, where iodine acts as the shallow donor level that supplies sufficient electrons and indium builds up the localized half-filled deep defect state in the band gap. The indium deep defect state traps electrons at a lower temperature and the trapped electrons will be thermally activated back to the conduction band when the temperature rises. In this way, the carrier concentration can be engineered as temperature-dependent, which matches the theoretically predicted optimized carrier concentration over the whole temperature range. As a result, a room temperature ZT of ∼0.4 and a peak ZT of ∼1.4 at 773 K were obtained in the n-type In/I co-doped PbTe, leading to a record-high average ZT of ∼1.04 in the temperature range of 300 to 773 K. Importantly, since deep defect levels also exist in other materials, the strategy of deep defect level engineering should be widely applicable to a variety of materials for enhancing the thermoelectric performance across a broad temperature range.

Graphical abstract: Deep defect level engineering: a strategy of optimizing the carrier concentration for high thermoelectric performance

Back to tab navigation

Supplementary files

Publication details

The article was received on 11 Jan 2018, accepted on 22 Feb 2018 and first published on 22 Feb 2018


Article type: Paper
DOI: 10.1039/C8EE00112J
Citation: Energy Environ. Sci., 2018,11, 933-940
  •   Request permissions

    Deep defect level engineering: a strategy of optimizing the carrier concentration for high thermoelectric performance

    Q. Zhang, Q. Song, X. Wang, J. Sun, Q. Zhu, K. Dahal, X. Lin, F. Cao, J. Zhou, S. Chen, G. Chen, J. Mao and Z. Ren, Energy Environ. Sci., 2018, 11, 933
    DOI: 10.1039/C8EE00112J

Search articles by author

Spotlight

Advertisements