| 摘要: | 近期有很多的工作投入尋找高效能的熱電材料, 因具備儲能的固態冷卻器及發電機有很高的市埸需求. 熱電元件具有潛在的綠能應用, 因其低空氣污染, 低噪音及非常長的使用期. 不過熱電元件仍存在沒法代替傳統冰箱及冷器機的障礙, 主要是其熱電優值(ZT)尚末大於3. 本理論計算將討論室溫下量子點奈米線的線性及非線性之熱電特性. 近來利用人體熱源來發展穿載熱電的電源是重要的課題. 熱電電源供應器可以提供手機及其他低功率電子元件電力. 因此設計低價位, 高效能的熱電的電源供應器是重要的課題. 雖然有不少的研究討論了量子點熱電特性, 但都局限於低溫下的應用討論. 室溫下的熱電效能, 至今尚未有相關的理論. 此兩年的計劃:第一年, 計算量子點奈米線室溫下的ZT. 第二年討論電子熱流二極體. 室溫下半導體聲子熱導是長度的倒數, 和載面積成正比, 因此我們必須討論小量子點的長奈米線. 庫倫交互作用及電子的穿隨效應是這研究的困難點之一. ZT值的計算局限在線性區間, 電子熱流二極體必須考慮非平衡態的電子傳輸, 計算難度更高. 我們在此計劃提出創新的奈米結構, 並証明該結構的量子點奈米線有電子熱流二極體特性. ;Recently, many efforts have been devoted to the search of high-efficiency thermoelectric (TE) materials, because of the high demand of energy-saving solid state coolers and power generators. TE devices have very good potential for green energy applications due to their desirable features, including low air pollution, low noise, and long operation time. However, currently there exists certain barrier for TE devices to replace conventional refrigerators and power generators since TE materials with figure of merit (ZT) larger than three are not yet reported. In this two year project, we would like to investigate TE properties of quantum dot nanowires at room temperature. Although many literatures have devoted to study TE efficiency of nanostructures such as quantum dots and quantum wires, few studies have reported high TE efficiency to materials at room temperature. The body-temperature as heat source to design wearable TE generators becomes a concerned topic in TE community. It is expected that wearable TE generators provide convenient powers for hand phones and other low-power electronics. Therefore, it is remarkable to propose a novel TE device with high efficiency at room temperature. This study will focus on the TE properties of nanowires with and without QDs, because it is expected that the thermal conductivity of nanowire is much smaller than that of bulk materials. The first year we plan to looking for the optimization of physical parameters to have high ZT values (in particular ZT larger than three at room temperature). In the second year, we will focus on the design of the heat diodes, which show the direction-dependent heat currents under a temperature bias at room temperature. |
