Details

Autor(en) / Beteiligte

• Li, Meng
• Sun, Qiang
• Xu, Sheng‐Duo
• Hong, Min
• Lyu, Wan‐Yu
• Liu, Ji‐Xing
• Wang, Yuan
• Dargusch, Matthew
• Zou, Jin
• Chen, Zhi‐Gang

Titel

Optimizing Electronic Quality Factor toward High‐Performance Ge1−x−yTaxSbyTe Thermoelectrics: The Role of Transition Metal Doping

Ist Teil von

• Advanced materials (Weinheim), 2021-10, Vol.33 (40), p.n/a

Ort / Verlag

Weinheim: Wiley Subscription Services, Inc

Erscheinungsjahr

2021

Quelle

Wiley Online Library Journals Frontfile Complete

Beschreibungen/Notizen

• Owing to high intrinsic figure‐of‐merit implemented by multi‐band valleytronics, GeTe‐based thermoelectric materials are promising for medium‐temperature applications. Transition metals are widely used as dopants for developing high‐performance GeTe thermoelectric materials. Herein, relevant work is critically reviewed to establish a correlation among transition metal doping, electronic quality factor, and figure‐of‐merit of GeTe. From first‐principle calculations, it is found that Ta, as an undiscovered dopant in GeTe, can effectively converge energy offset between light and heavy conduction band extrema to enhance effective mass at high temperature. Such manipulation is verified by the increased Seebeck coefficient of synthesized Ge1−x−yTaxSbyTe samples from 160 to 180 µV K−1 at 775 K upon doping Ta, then to 220 µV K−1 with further alloying Sb. Characterization using electron microscopy also reveals the unique herringbone structure associated with multi‐scale lattice defects induced by Ta doping, which greatly hinder phonon propagation to decrease thermal conductivity. As a result, a figure‐of‐merit of ≈2.0 is attained in the Ge0.88Ta0.02Sb0.10Te sample, reflecting a maximum heat‐to‐electricity efficiency up to 17.7% under a temperature gradient of 400 K. The rationalized beneficial effects stemming from Ta doping is an important observation that will stimulate new exploration toward high‐performance GeTe‐based thermoelectric materials. The nexus between electronic quality factor and thermoelectric figure‐of‐merit in transition‐metal‐doped GeTe, which can serve as a facile yet efficient descriptor for high‐throughput screening of good thermoelectric materials, is explained. To clarify this point, Ta‐doped GeTe is designed with optimized electronic quality factor, rendering a figure‐of‐merit over 2.0 and a conceptional efficiency over 15%.