綠能與節能材料之第一原理研究

Abstract

儘管文獻已經廣泛討論過：（1）使用銳鈦礦奈米管形成的薄膜作為染料敏化太陽能電池的光電極以及（2）拓樸絕緣體，然而針對銳鈦礦奈米管的表面修飾與拓樸絕緣體異質接面的的研究則較為相對缺乏。本篇論文探討使用密度泛函理論來研究銳鈦礦奈米管表面官能基吸附與氧化鎂長晶在硒化鉍上。此研究將焦點置於在不同酸鹼性溶液下進行銳鈦礦奈米管表面修飾、甲酸根離子對奈米管表面的吸附以及拓樸絕緣體異質接面的自旋極化量。計算的電子結構其性質都被分類和量化，用以對照實驗上觀測到的現象。研究的結果指出(1)在酸性溶液中進行奈米管表面修飾的效果較之鹼性溶液佳，甲酸根離子的吸附，在我們的研究當中只有一種吸附形式是穩定的；（2）對於不同的量測能量，自旋極化量會因覆蓋k點範圍的情況產生不同的螺旋性，使的電子自旋結構發生翻轉，進而自旋極化電流減小。

While （1）the thin film of anatase nanotube of electrode of DSSCs and （2） topological insulators have been extensively investigated, the surface modification of anatase nanotube and the hetero junction of topological insulators are relatively unexplored. This thesis studies DFT calculation of radicals absorption of anatase nanotube and magnesium oxide on bismuth selenide. The research focused on the surface modifications of anatase nanotube in different pH-value solutions、formic acid ion absorption on tube surface and spin polarizations of hetero junction of topological insulator. Properties of electronic structures are categorized and quantified in order to ascertain the observed phenomenon in the experiments. The results suggest that （1） the nanotube surface modification in low pH-value solutions is better than in high pH-value solutions and only one form of HCOO- absorption is stable in this work；（2）the spin polarized current reduced as the spin inversion occurred with the range of k-points at one energy value.