- 學位論文
以鈦(III)離子製備石墨烯並將其應用於可撓式染料敏化太陽能電池
Synthesis of graphene using titanium(III) ions, and it's application of flexible dys-sensitized solar cells.
摘要
本研究的第一部份是石墨烯的製備，我們主要是利用氧化還原的方式來製備少層堆疊的石墨烯。先利用Hummers法將石墨塊材剝離成片狀的氧化石墨烯，再利用鈦金屬在酸性溶液中解離出的鈦(III)離子來進行還原。我們發現當系統中同時存在著鈦金屬與鈦(III)離子時，其還原效果遠高於反應系統中僅存有鈦(III)離子。從X-ray光電子能譜儀的分析中得知，當系統為鈦以及鈦(III)離子共存時，其還原石墨烯具有極高的碳氧比(23.44)，且整個還原製程不需涉及高溫，非常適合用來製作軟性的石墨烯電極。 本研究的第二部分則是利用鈦(III)離子還原法，製做出軟性石墨烯電極，並應用於染料敏化太陽能電池的對電極。在這一個部份，我們製備出了兩種不同結構的石墨烯電極，一個是緻密結構，一個是多孔性結構。而其光電轉換效率有非常大的差異，緻密結構的僅有1.61 %，而多孔性結構的可高達5.45 %，與白金電極非常接近(5.52 %)。我們以掃描式電子顯微鏡、電化學阻抗頻譜以及循環伏安法，來探討其石墨烯電極結構是如何影響光電轉換效率。在本章節的最後，我們進一步的附載少量的白金粒子於石墨烯上，其效率可提升到5.87 %。 本研究的第三部分為可撓式染料敏化太陽能電池。首先先針對附載白金粒子的石墨烯電極進行耐久度的測試，其石墨烯電極在經由1500次的撓曲之下，轉換效率從5.75 %衰退至5.09 %。再來是製備軟性的TiO2工作電極，在經由一系列的優化處理後，其軟性工作電極的效率為4.85 %。我們進一步的將白金電極置換成附載白金粒子的軟性石墨烯電極，組裝成可撓式的染料敏化太陽能電池，其轉換效率可高達5.30 %。
並列摘要
The first part of this study was the preparation of graphene. We prepare few-layer stacked graphene sheet mainly using redox method. We first exfoliated graphite into graphene-oxide nano sheet by using Hummers method. Then, using titanium(III) ions dissolved from titanium metallic powder in acid solution, to reduce graphene-oxide. We found that when the system is in the simultaneous existence of titanium metal and titanium (III) ions, the reduction ability is much higher than the reaction system containing only titanium (III) ions. From X-ray photoelectron spectroscopy analysis, we confirmed that when the titanium and titanium (III) ions was coexist, the reduced-graphene has a very high carbon to oxygen ratio (23.44). The second part of this study was the prepartion of graphene electrode by using titanium(III) ions reduction method, and applied to the counter electrode of dye-sensitized solar cells. In this part, we have prepared two different structures of the graphene electrode, one is a dense structure, another one is a porous structure. The photoelectric conversion efficiency of dense structure was 1.61%, while the porous structure was 5.45 %, which was comparable to the platium electrode (5.52 %). We use field emission scanning electron microscopy, electrochemical impedance spectra and cyclic voltammetry to investigated into how the porous structure affect the photoelectric conversion efficiency. In the final of this chapter, we further loaded a small amount of platinum particles at graphene nano sheet, and its efficiency can be raised to 5.87%. The third part of this study was the flexible dye-sensitized solar cells. First, we exame the durability of the flexible Pt-graphene electrode by bending it for 1500 times. Aftter 1500 times bending, the photoelectric conversion efficiency of the Pt-graphene electrode decayed from 5.75 % to 5.09 %. Then, we prepared a flexible TiO2 working electrode, and through a series of optimization treatment, the photoelectric conversion efficiency was achieve 4.85 %(the counter electrode was Pt). We further replace Pt electrode by Pt-graphene electrode, and the photoelectric conversion efficiency was raised to 5.30 %.