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高分子及二氧化鈦奈米晶體混成材料中溫度變化載子遷移率之特性研

时间:2009年10月20日来源:职称论文网 作者:曾云亨 点击:
  【关键词】特性,材料,of,and,the,in,J.,mobilit

中文關鍵字 混摻太陽能電池結構 載子遷移率 二氧化鈦
英文關鍵字 bulkheterojunction structures charge carrier mobility titanium dioxde
學科別分類 學科別>應用科學>材料工程

中文摘要 有機光伏打元件中混摻異質接面結構可增加電子受體/予體異質接面的接觸面因而有效的提升載子分離機制。然而高分子鏈的雜亂排列將降低有效載子遷移率。本研究主要是藉由變化溫度及電場量測高分子P3HT及二氧化鈦奈米晶體混成材料中的載子遷移率,並導用高斯亂度模型(Gaussian disorder models)以了解在不同長度及濃度的混成晶體中,其能量亂度(energetic disorder)與位置亂度(positional disorder)和載子傳導機制之間的關係。我們藉由改變奈米晶體大小及混摻濃度來改變混成系統中載子傳導的特性,並以線性增加電壓抽取電流(Current extraction by linearly increase voltage)方法量測在不同溫度下主要載子傳輸率,實驗結果顯示在混摻二氧化鈦奈米晶體後室溫中有效載子遷移率有很大的提升並可以有效的降低能量亂度以及提升位置亂度。能量亂度的下降表示載子跳躍的能障可以有效的降低,而提升位置亂度表示載子波型函數的重合(overlap)變化增加,可以有效的增加載子跳躍的位置及傳輸率因而有利於載子之傳導。
英文摘要 The bulk heterojunction structures of organic photovoltaic increase the donor/acceptor interfaces greatly and in favor of the charge separation, but the disorder extent of the polymer matrix would cause inefficient charge transport. The phonon-assisted hopping in disorder conjugate polymer matrix is employed to explain the charge transport mechanism. In this work, the charge carrier mobility of the organic/inorganic hybrid bulk heterojunction structures will be addressed based on the P3HT/TiO2 hybrid materials by employing the charge extraction by linearly increase voltage (CELIV) method. By adding different concentrations and sizes of the TiO2 nanocrystals, an enhancement of mobility can be observed. From temperature dependent CELIV measurement, the energetic and positional disorder parameters would be discussed. The result shows that the values of energetic disorder parameter decreases with increasing TiO2 hybrid concentration which is corresponding to the decrease of the Gaussian distribution width and hence the energy barrier of upward hopping decreased. Also an enhancement in positional disorder parameters would be observed, which indicating large variance of wavefunction overlap providing more efficient transport paths for carriers to transport and detour energetic unfavorable sites after hybrid with TiO2 nanorystals.
論文目次 審定書…………………………………………………………..I
誌謝…………………………………………………………….II
摘要……………………………………………………….......III
Abstract………………………………………………………..IV
Table of contents………………………………………….........V
Figures…….……………………………………………..….VIII

Chapter 1 Introduction 1
1.1 Alternative energy sources 1
1.2 Conventional inorganic solar cells 2
1.3 Organic/Polymer Solar Cell 4
1.4 Structure evolution of organic solar cell 6
1.5 Transport properties of bulkheterojunction structures 9
1.6 Research motivation 12
Chapter 2 Charge Transport in disordered materials 13
2.1 Introduction 13
2.2 Band structures for ordered/disordered materials 13
2.3 Hopping transport of charge carriers in disordered molecules 15


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