異質接面二維石墨烯-硒化物之熱電性質

Thermoelectric Properties of 2D Graphene-Selenides Heterojunction

吳仁凱(Jen-Kai Wu)

指導教授 ： 張顏暉

共同指導教授 ： 謝雅萍(Ya-Ping Hsieh)

國立臺灣大學/理學院/物理學研究所/博士(2020年)

https://doi.org/10.6342/NTU202002053

摘要

數十年來，對環保和不斷增長的發電需求推動了熱電材料的發展。二維材料的最新發現像是提高聲子散射和增強結晶度，為這一活躍的研究領域提供了新的動力。二維熱電元件與塊材熱電元件相比已顯示出較強的性能，但由於在有限的尺寸下聲子邊界散射變得無效，因此無法通過奈米結構輕易地進行改進。
為了克服此問題，我們引入了一種一維紋理化方法，可有效抑制二維熱電晶粒之間的聲子傳輸。利用高度定向的單軸石墨烯皺紋分離高品質的硒化物薄膜。這些紋理化樣品的熱電特性表現出很強的各向異性，室溫下的最大熱電優值分別為1.03 (硒化鉍)、0.372 (二硒化錫)和1.02 (硒化銅)，這是目前為止此三種材料得到的最高報導值。另外，二硒化錫/石墨烯在微小應變下(小於0.2 %)，因應變感應致電荷轉移而顯示出良好的電阻響應且應變計因數約為50，這表明它在小應變下可以是良好的應變傳感器。
引入紋理化方法為將來的應用提供了增強二維熱電元件的途徑，並且適用於任何二維熱電元件。

關鍵字

二維材料 ； 熱電 ； 石墨烯 ； 硒化物

並列摘要

The ever increasing demand for environmentally friendly and ubiquitous power generation has driven the development of thermoelectric materials for decades. The recent discovery of Two-dimensional (2D) materials, like enhanced crystallinity and increased phonon scattering, has provided new impulses to this active research field. 2D thermoelectrics have shown enhanced performance compared to bulk thermoelectrics but cannot easily be improved through nanostructuring since phonon-boundary scattering becomes ineffective under confined dimensions.
To overcome this issue, we introduce a one-dimensional (1D) texturing approach that efficiently suppresses phonon transport between grains of 2D thermoelectrics. Uniaxial graphene wrinkles were utilized to separate high-quality, ultrathin selenides films in a highly directional manner. The thermoelectric properties of these textured samples exhibit a strongly anisotropic characteristic with a maximum ZT of 1.03 (Bi2Se3), 0.372 (SnSe2), and 1.02 (CuSe) at room temperature, which represents the highest reported value for the materials, respectively. Surprisingly, SnSe2/graphene shows good resistance response (gauge factor~ 50) which suggests it can be a good strain sensor.
The texturing approach provides a route for the enhancement of 2D thermoelectrics for future applications and is applicable to any 2D thermoelectrics.

並列關鍵字

two dimensional ； thermoelectrics ； graphene ； selenides

參考文獻

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