本論文討論了三顆串接耦合量子點的能源回收引擎之效率，該引擎將環境中的熱能轉換成電能。藉由引入外部負載，解系統的自洽方程式，可以推得能源回收引擎的穿隧電流、感應熱電位以及回收效率。我們發現系統於溫差驅動之下，其電流行為會呈現雙極效應。除此之外，穿隧電流與熱電位間遵循熱電的冷次定律。回收效率的最大值傾向發生於三顆串接耦合量子點系統處於軌道空態的情形，但效率容易受到冷端溫度及溫度差的影響。量子點間距影響電子的躍遷強度，使得效率會在特定條件達到最大值。然而，因量子點尺寸大小相異形成的量子點能階不均勻，使得效率大幅降低。即便量子點不均勻對回收效率影響甚劇，但可利用此製作新穎的熱電元件：溫差驅動之電流二極體。在非線性響應區間之下，階梯狀分布的量子點能階可產生具方向性的電流行為。若以整流率為基準判斷元件的優劣，經由調控量子點之間的距離以及尺寸大小，可以提升二極體的整流率，達到元件的最佳化設計。

The nonlinear transport properties of serially coupled triple quantum dots system (SCTQD) connected to the metallic electrodes is theoretically investigated in the Coulomb blockade regime for the application of energy harvesting engines (EHE). The thermal-induced voltage is solved self-consistently. Electron currents driven by a temperature difference shows the bipolar oscillatory behavior with respect to QD energy levels. The maximum efficiency of EHE occurs for SCTQD in the orbital depletion situation rather than electron orbital-filling situation. The efficiency of EHE increases with increasing a temperature-bias. In addition, we have investigated how the efficiency of EHE is influenced by the electron- hopping strengths, and QD energy level fluctuations (QDELF). Despite, the efficiency of EHE is seriously suppressed by QDELF, which is useful to design an electron diode driven by a temperature bias. We find that a SCTQD with staircase energy level structures shows the direction-dependent currents derived by a temperature bias.

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