以脫層蒙脫石/多壁奈米碳管/聚合型離子液體製作軟質固態電解質之製程及其在染料敏化太陽能電池之應用

Fabrications of Flexible Solid Electrolytes Composed of Exfoliated Montmorillonite/Multi-walled Carbon Nanotubes/Polymerized Ionic Liquids and Their Applications on Dye-Sensitized Solar Cells

顧元斌(Yuan-Bin Gu)

指導教授 ： 林金福

國立臺灣大學/工學院/材料科學與工程學研究所/碩士(2015年)

https://doi.org/10.6342/NTU.2015.00153

摘要

本實驗首先合成一種可進行聚合反應的苯乙烯官能基的釕金屬染料Ru-S，并利用NMR、UV-vis光譜等方法鑑定其結構，同時還合成了聚合型離子液體1-(2-acryloyloxy-ethyl)-3-methylimidazol-1-ium iodide (AMIMI)，也用NMR測定其結構。并以UV-Vis光譜測試Ru-S吸附在TiO2表面後以不同濃度AMIMI的ACN溶液進行共聚合反應後的脫附實驗，探討其與TiO2鍵結的穩定性。
在太陽能電池元件的表現上，由於AMIMI黏度太高，本實驗設計了五種不同比例的EMII/AMIMI (1-Ethyl-3-methylimidazolium Iodide)進行稀釋，分別為1:4、1:3、1:2、1:1、2：1。實驗發現隨著EMII添加量的增加，電解質的黏度明顯降低、效率隨之提升，在EMII：AMIMI=1：1時，系統有最大效率，效率從原本的3.99%提升至5.87%。隨後將不同比例的exMMT加至EMII:AMIMI=1：1的電解質製作的DSSC后，發現隨著exMMT添加量的增大，其Voc上升，Jsc與效率都會明顯提升，當加入exMMT量達到1%時達到最大值，從不加exMMT的5.03 %提高到5.83%，推測因為exMMT的加入促進了I-氧化成I3-，使電解質中有更多離子幫助傳導。接著將不同比例的MWCNT加入EMII:AMIMI=1：1的電解質製作的DSSC中，可發現MWCNT的加入明顯提升了元件的Jsc，更是將效率從未加MWCNT的5.15%提升至6.19%，添加量為0.2wt%時最佳。推測原因是因為奈米碳管的加入能幫助電子導電，使電流上升。另外將不同比例的exMMT加入含有0.2wt%的MWCNT的電解質組成的DSSC後發現，在添加量達到1wt%時電池效率從6.19%提升至6.42%，而增加太多exMMT效率下降明顯。推測原因是因為只含MWCNT的元件本身存在MWCNT可以幫助電子導電，而少量的exMMT加入影響不明顯，加至1%時因exMMT幫助I-轉變成I3-可以幫助離子導電，兩者效應可發出促進，因此效率變高，但加入exMMT太多膠態系統容易過度硬化反而降低效應。
而對元件的長效性分析可以發現添加MWCNT後電池元件穩定性遠大於只含有EMII/AMIMI的體系，在經過一個月后添加MWCNT的電池仍保有7成以上的效率，而不加MWCNT的體系只剩下2成。將做完長效性的試片打開并用SEM觀察其表面形貌發現經過長效處理的試片因AMIMI聚合而產生裂紋，且添加MWCNT的試片裂紋較多且大，這可能是因為MWCNT導熱係數高，照光時AMIMI聚合硬化速度快而加速龜裂。

關鍵字：EMII；AMIMI；RuS；離子液體；exMMT；MWCNT；DSSC；長效

關鍵字

EMII ； AMIM ； RuS ； 離子液體 ； 脫層蒙脫石 ； 奈米碳管 ； 染料敏化太陽能電池 ； 長效

並列摘要

We synthesized the crosslinkable ruthenium complex with styryl groups attached on the bipyridine ligand, denoted as Ru-S which was characterized by NMR and UV-vis spectroscopies for this study. And we also synthesized 1-(2-acryloyloxy-ethyl)-3-methylimidazol-1-ium iodide (AMIMI), a polymerizable ionic liquid. The stability of Ru-S after crosslinking and copolymerization with different concentrations of AMIMI in ACN solutions were investigated by UV-vis spectroscopy through rinsing with NaOH aqueous solution to remove the unreacted RuS.
In order to decrease the viscosity of AMIMI ionic liquid electrolyte, EMII was added to prepare five different weight ratios of EMII/AMIMI. The power conversion efficiency (PCE) of resulting DSSCs was increased when the content of EMII was increased. The PCE was increased from 3.99% to 5.87% when the weight ratio of EMII/AMIMI reached 1:1. Then different contents of exMMT were incorporated into the eletrolytes with EMII/AMIMI=1:1 for the DSSC. The Jsc and PCE were both increased with increasing the content of exMMT. The PCE reached up to 5.83% when the content of exMMT was 1 wt%. It is because the presence of exMMT can promote the oxidation of I- to I3-. Moreover, different contents of MWCNT were also incorporated into the eletrolytes with EMII/AMIMI=1:1 for the DSSC. The presnence of MWCNT could also increase the Jsc and PCE of the resulting DSSC . The PCE could reach up to 6.19% as 0.2wt% MWCNT was incorporated. It is because the presence of MWCNT can increase the conductivity of the electrolyte. Then different contents of exMMT was incorporated into the eletrolytes with EMII/AMIMI=1:1 and 0.2wt% MWCNT for DSSC. The best performance of DSSC had the PCE increased from 6.19% to 6.42% as 1 wt% exMMT was incorporated. That is because the MWCNT can increase the conductivity of the electrolyte, and exMMT can promote the oxidation of I- to I3-. When the content of exMMT was more than 1 wt%, the system would be over the gel point and reduce the effects.
The long term service inverstingaion of DSSC showed that the stability of the DSSC with MWCNT was much greater than that without MWCNT. The PCE of the devise with MWCNT could remain more than 70% after testing for one month. However the PCE of the devise without MWCNT decreased to only 20%. Then we open the device and investigated the morphology of the electrolyte surface with SEM. More cracks have been produced on the layer of polymerized ionic liquid electrolyte in the device with MWCNT. It indicated that MWCNT with high thermal conductivity might accelerate the polymerization of AMIMI under the exposure of sunlight during long term testing.

Keyword: EMII；AMIMI；RuS；Ionic Liquids；exMMT；MWCNT；DSSC; long term

並列關鍵字

EMII ； AMIMI ； RuS ； Ionic Liquids ； exMMT ； MWCNT ； DSSC ； long term

參考文獻

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