有限長度石墨稀奈米帶的熱電特性;Thermoelectric properties of finite size graphene nanoribbons

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Title:	有限長度石墨稀奈米帶的熱電特性;Thermoelectric properties of finite size graphene nanoribbons
Authors:	黃康儼;Huang, Kang-Yan
Contributors:	電機工程學系
Keywords:	熱電特性;石墨稀;2D matrials
Date:	2022-06-23
Issue Date:	2022-07-14 01:19:54 (UTC+8)
Publisher:	國立中央大學
Abstract:	從舊有的文獻得知，石墨稀有兩種不同的排列，會造成截然不同的特性。第一種是armchair graphene nanoribbons具有半導體特性，另一種是zigzag graphene nanoribbons具有金屬特性，但以熱電材料來說，armchair graphene nanoribbons會有較高的熱電優值，因此本碩論會著重在這一塊。接著利用電子流與電子熱流去推導出電導、席貝克、功率因素以及熱電優值，從模擬中的結果可以發現，增加nanoribbons的線寬會造成bandgap的縮小，這可以證實Quantum confinement所帶來的效應。我們也觀察到armchair graphene nanoribbons的功率因素和ZT的最大值主要發生在bandgap的兩端點，若要有良好的熱電轉換效率，聲子熱導k_ph要越小，而席貝克係數S和電導G_e要越大，因為這些參數彼此會互相影響，因此使ZT值的增加變得困難，這是目前研究需要突破的地方。;It is known from the old literature that there are two different arrangements of graphene, which result in very different properties. The first one is that armchair graphene nanoribbons have semiconducting properties, and the other is that zigzag graphene nanoribbons have metallic properties, but in terms of thermoelectric materials, armchair graphene nanoribbons have higher thermoelectric figure of merit, so this thes is will focus on this one. Then use electron flow and electron heat flow to deduce conductance, Seebeck, power factor and thermoelectric figure of merit. From the results in the simulation, it can be found that increasing the line width of nanoribbons will cause the bandgap to shrink, which can greatly confirm the effect of Quantum confinement effect. We also observed that the power factor and ZT maxima of armchair graphene nanoribbons mainly occur at the two ends of the bandgap. To have great thermoelectric conversion efficiency, the phonon thermal conductance k_ph should be smaller, while the Seebeck coefficient S and conductance Ge. If it is larger, because these parameters will affect each other,it becomes difficult to increase the ZT , which is where the current research needs to break through.
Appears in Collections:	[Graduate Institute of Electrical Engineering] Electronic Thesis & Dissertation

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