共軛高分子/奈米顆粒陣列結構應用於高分子太陽能電池之研究

Abstract

本論文利用陽極氧化鋁(AAO)模板製備聚共軛高分子/奈米顆粒一維奈米棒陣列結構後分別針對陣列奈米結構分析、太陽能電池元件的結構設計以及奈米棒尺寸對元件效率的影響等逐步深入探討。其中依序針對奈米結構與元件性質探討：(1)穿隧式電子顯微鏡與導電模式之原子力顯微鏡分析奈米棒之殼層結構、(2)奈米棒尺寸部分: 針對一系列不同尺寸的奈米棒尺寸對元件的內部量子轉換效率、外部量子轉換效率與太陽能電池元件效率的影響進行研究、(3)太陽能電池元件結構部分: 針對一般結構(normal structure)與反式結構(inverted structure)來討論不同元件結構對元件效率的影響、(4)研究奈米棒的電洞傳導與元件效率的關係、(5)導入不同奈米顆粒於此一維陣列結構中，增加其在太陽能電池元件研究的廣度。我們可以非常有系統的找出元件效率與奈米棒陣列結構間的關聯性。此完整的研究內容對未來高效率高分子太陽能電池的製作極具貢獻，其研究充分的被參考及引用。 此外，高分子太陽能電池的新材料開發上我們使用Grignard metathesis聚合法合成一系列具有強拉電子oxadiazole (OXD)基團之共軛高分子。在導入最佳比例的拉電子OXD基團下，使高分子在適度的結晶條件下以及在短波長區域(~304nm)具備額外的吸收波段，進而提升了高分子太陽能電池元件之效率。

The main objective of this dissertation is to study the performance of polymer heterojunction solar cell involving conjugated polymers/nanoparticles incorporating nanostructured rod arrays of device. In the introduction of this dissertation, we gave an explanation on the historical evolution of polymer nanocomposites heterojunction solar cell, and summarized the literatures in the recent years. In the chapter 2, we have used melt-assisted wetting of porous alumina templates to prepare ordered core–shell nanorod arrays of poly(3-hexylthiophene) (P3HT) and [6,6]-phenyl-C61-butyric acid methyl ester (PCBM). This particular core–shell nanorod arrays are characterized by using transmission electron microscopy and conductance atomic force microscopy, which revealed the presence of phase-separated shell (p-type) and core (n-type) regions. Under illumination, we observed a variation of several picoamperes between the currents in the core and shell regions of the P3HT/PCBM nanorod arrays. In the chapter 3, the internal quantum efficiencies (IQE) and external quantum efficiencies (EQE) of these core/shell nanorod inverted solar cells were higher than those of the corresponding conventional inverted bulk heterojunction device. The optimized nanorod array structure had a high hole mobility that was over one order magnitude greater than that of the conventional BHJ structure, as determined by fitting the dark J–V curves into the space charge–limited current model. The more efficient carrier transport of the device incorporating the core/shell nanorod arrays provided it with both a higher short-circuit current density and power conversion efficiency. The rod array devices incorporating titanium dioxide nanorod/P3HT were discussed in chapter 4. This arrays was revealed that phase-separated TiO2 rich (n-type) and P3HT rich (p-type) regions. The optimized composite array structure had a higher hole mobility than that of the film consisting of TiO2 nanorod and P3HT blend evidenced by fitting the dark J–V curves into the space charge–limited current model. In the chapter 5, we have used Grignard metathesis polymerization to prepare poly(3-hexylthiophene)-based copolymers containing electron-withdrawing 4-tert-butylphenyl-1,3,4-oxadiazole-phenyl moieties as side chains. The quenching effects was observed in the photoluminescence spectra of the copolymers incorporating pendent electron-deficient 1,3,4-oxadiazole moieties on the side chains. The photocurrents of devices were enhanced in the presence of an optimal amount of the 1,3,4-oxadiazole moieties, thereby leading to improved power conversion efficiencies.