Deep defect level engineering: a strategy of optimizing the carrier concentration for high thermoelectric performance
| Autor: | Jiawei Zhou, Keshab Dahal, Gang Chen, Shuo Chen, Xinyu Wang, Qichen Song, Jun Mao, Qing Zhu, Feng Cao, Jingying Sun, Xi Lin, Qian Zhang, Zhifeng Ren |
|---|---|
| Rok vydání: | 2018 |
| Předmět: |
Materials science
Renewable Energy Sustainability and the Environment Band gap business.industry Doping chemistry.chemical_element 02 engineering and technology Electron Atmospheric temperature range 010402 general chemistry 021001 nanoscience & nanotechnology 01 natural sciences Pollution 0104 chemical sciences Nuclear Energy and Engineering chemistry Thermoelectric effect Environmental Chemistry Optoelectronics 0210 nano-technology business Indium Shallow donor Order of magnitude |
| Zdroj: | Energy & Environmental Science. 11:933-940 |
| ISSN: | 1754-5706 1754-5692 |
| Popis: | 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. |
| Databáze: | OpenAIRE |
| Externí odkaz: |
|