本論文中利用Hubbard模型與Anderson模型來研究三個量子點串接耦合而成的分子與金屬電極連接形成的接面系統之熱電特性。利用格林函數，我們可以得到量子點系統中的電子狀態密度。在格林函數的建立上，我們考慮了平均場論和多體理論兩種推導方法。我們藉由凱帝旭格林函數的技巧可以計算出系統中的電流及熱流，探討在線性響應區下的電導、塞貝克(Seebeck)係數、電子熱導以及熱電優值(ZT)。我們發現使用平均場論時所得到的熱電優值是高估於多體理論的。在低溫區，塞貝克係數會在Hubbard能隙中出現異常的提升。在高溫區，電導會高估。此外，我們利用多體理論的方法來分析及討論量子點大小不一致、量子點間電子跳躍強度和庫倫交互作用改變時對於熱電優值的影響。 The thermoelectric properties of a serially coupled triple quantum dot molecule connected to the metallic electrodes are theoretically studied by using the Hubbard model and Anderson model. The charge and heat currents are calculated in the framework of Keldysh Green’s function technique. The electrical conductance, Seebeck coefficient, electron thermal conductance and figure of merit(ZT) are calculated in the linear response regime. We consider two procedures to evaluate Green’s functions : mean-field theory and many-body theory. We find that the ZT calculated by the mean-field theory is overestimated, in the comparison between two theories. In the low temperature regime, Seebeck coefficient appears an abnormal enhancement in the Hubbard gap. In the high temperature regime, the electrical conductance is overestimated. Based on the many-body theory, the effects of quantum dot size fluctuation, interdot hopping strength variation and interdot Coulomb interaction change on the figure of merit are analyzed and discussed.
