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Bi2SeO2 is a promising n-type semiconductor to pair with p-type BiCuSeO in a thermoelectric (TE) device. The TE figure of merit zT and, therefore, the device efficiency must be optimized by tuning the carrier concentration. However, electron concentrations in self-doped n-type Bi2SeO2 span several orders of magnitude, even in samples with same nominal compositions. Such unsystematic variations in the electron concentration has a thermodynamic origin related to the variations in native defect concentrations.
In this study, we use first-principles calculations to show that the selenium vacancy, which is the source of n-type conductivity in Bi2SeO2, varies by 1–2 orders of magnitude depending on the thermodynamic conditions. We predict that the electron concentration can be enhanced by synthesizing under more Se-poor conditions and/or at higher temperatures (TSSR), which promote the formation of selenium vacancies without introducing extrinsic dopants. We validate our computational predictions through solid-state synthesis of Bi2SeO2. We observe more than two orders of magnitude increase in the electron concentration by solely
adjusting the synthesis conditions. Additionally, we reveal the significant effect of grain boundary scattering on electron transport in Bi2SeO2, which is controlled by adjusting TSSR. By simultaneously optimizing the electron concentration and mobility, we achieve a zT of ∼0.2 at 773 K for self-doped n-type Bi2SeO2. Our study highlights the need for careful control of thermodynamic growth conditions and demonstrates TE performance improvement by varying synthesis parameters.

権利情報:

• In Copyright
  

  This is the peer reviewed version of the following article: Andrei Novitskii, Michael Y. Toriyama, Illia Serhiienko, Takao Mori, G. Jeffrey Snyder, Prashun Gorai. Defect Engineering of Bi2SeO2 Thermoelectrics. Advanced Functional Materials. 2024, 35 (10), 2416509, which has been published in final form at https://doi.org/10.1002/adfm.202416509. This article may be used for non-commercial purposes in accordance with Wiley Terms and Conditions for Use of Self-Archived Versions. This article may not be enhanced, enriched or otherwise transformed into a derivative work, without express permission from Wiley or by statutory rights under applicable legislation. Copyright notices must not be removed, obscured or modified. The article must be linked to Wiley’s version of record on Wiley Online Library and any embedding, framing or otherwise making available the article or pages thereof by third parties from platforms, services and websites other than Wiley Online Library must be prohibited.

キーワード: thermoelectric

刊行年月日: 2024-12-29

出版者: Wiley

掲載誌:

• Advanced Functional Materials (ISSN: 16163028) vol. 35 issue. 10 2416509

研究助成金:

• Japan Science and Technology Agency JPMJMI19A1
• Japan Science and Technology Agency JPMJMI19A1
• Japan Science and Technology Agency JPMJMI19A1
• Japan Science and Technology Agency JPMJSP2124
• Japan Science and Technology Agency JPMJSP2124
• Japan Science and Technology Agency JPMJSP2124
• Office of Science DE‐SC0020347
• Center for Hierarchical Materials Design 70NANB19H005
• Center for Hierarchical Materials Design 70NANB19H005
• Division of Materials Research DMR‐2102409

原稿種別: 著者最終稿 (Accepted manuscript)

MDR DOI: https://doi.org/10.48505/nims.5888

公開URL: https://doi.org/10.1002/adfm.202416509

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更新時刻: 2025-11-11 11:26:52 +0900

MDRでの公開時刻: 2026-01-02 17:31:04 +0900