鉑金與氣相成長碳纖維複合材於染料敏化太陽能電池之應用

Application of Platinum / vapor grown carbon fiber (VGCF) composite for dye sensitized solar cells

李冠儒(Kuan-Ju Li)

指導教授 ： 陳龍泉

崑山科技大學/工程學院/材料工程研究所/碩士(2012年)

摘要

本研究製備氣相成長碳纖維(VGCF)與鉑金(Pt)的複合材料，利用刀刮法於FTO導電玻璃上製作染料敏化太陽能電池(DSSC)的對電極，討論VGCF、Pt、以及VGCF/Pt複合材對電極的物理性質；並將這些對電極與二氧化鈦工作電極組合成DSSC，探討VGCF、Pt以及不同比例的VGCF/Pt複合材在不同熱處理溫度的光電轉換效率。
由SEM及TEM分析可看出Pt均勻分散且附著於VGCF的表面，X光繞射(XRD)分析可明顯看出VGCF/Pt複合材中有鉑金及VGCF的特徵峰，拉曼分析可看出VGCF/Pt複合材的D band對G band強度比值(D/G)大於純VGCF者，由電化學阻抗分析圖譜可看出VGCF/Pt複合材有較低的電荷轉移阻抗；循環伏安法可觀察VGCF/Pt複合材比純VGCF及純Pt對I3-還原為I-有較佳的催化能力；塔佛曲線分析指出VGCF/Pt複合材比純VGCF及純Pt有較高的交換電流密度，反映出較低的還原過電位。化學分析電子光譜儀分析(ESAC)顯示熱處理溫度提升有助於VGCF/Pt複合材中鉑金的還原程度，但熱重分析(TGA)顯示VGCF在530℃以上會開始裂解。VGCF及Pt以7:3比例複合，經450℃熱處理後可得DSSC光電轉換效率7.77%，優於其他複合材料的比例；而VGCF/Pt以7:3比例複合且經530℃熱處理可得光電轉換效率8.15%，優於其他熱處理溫度。

關鍵字

染料敏化太陽能電池 ； 氣象成長碳纖維 ； 鉑金 ； 二氧化鈦對電極 ； 化學分析電子光譜

並列摘要

This study is to employ vapor grown carbon fiber (VGCF) and platinum (Pt) composite materials as the counter electrodes by the doctor blade method for the dye sensitized solar cells (DSSCs) application. The physical and chemical properties of the VGCF/Pt composites and the performance of DSSCs based on the VGCF/Pt counter electrodes were investigated.
SEM and TEM analyses indicate that the Pt particles dispersed uniformly on the VGCF surface. X-ray diffraction (XRD) analysis exhibits both peaks of VGCF and Pt of the VGCF/Pt composites. Raman analysis demonstrates that the D/G band intensity of VGCF/Pt composite is larger than that of pure VGCF. Electrochemical impedance analysis explores a lower charge transfer resistance for VGCF/Pt composite than that of pure VGCF and pure Pt alone. The same tendency was also supported by cyclic voltammetry and Tafel curves because VGCF/Pt composites show high ability toward the reduction of I3- to I-. X-ray photoelectrons measurement illustrates that increasing calcination temperature can enhance the reduction level of Pt(IV) to Pt(0). Thermal gravimetric analysis (TGA) shows that compositing Pt with VGCF can improve the thermal stability of VGCF. The DSSCs based on 450℃-calcined VGCF/Pt counter electrode with weight ratio of 7/3 display the highest photo-to-electricity conversion of 7.77% among the ratios examined. Increasing the calcination temperature of VGCF/Pt from 450℃ to 530℃ enhances photo-to-electricity conversion efficiency from 7.77 to 8.15%, however, the conversion efficiency inversely decreases as further increasing the calcination temperature due to the thermal instability of VGCF.

並列關鍵字

dye-sensitized solar cell ； vapor grown carbon fiber ； platinum ； titanium dioxide ； counter electrode ； x-ray photoelectron

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