高分子型分散劑之設計合成與奈米材料分散及染料敏化太陽能電池應用

Synthesis of Polymeric Dispersants for Nanomaterials and Dye-Sensitized Solar Cells

施柏達(Po-Ta Shih)

指導教授 ： 林江珍

國立臺灣大學/工學院/高分子科學與工程學研究所/博士(2015年)

https://doi.org/10.6342/NTU.2015.01203

摘要

今日奈米材料已廣泛被應用於各種產業，針對奈米材料之應用及製備具自我排列特性的奈米材料，分散技術實為製程中之關鍵。其中奈米碳材如奈米碳管及石墨烯在水相及有機相之分散對於奈米材料及其下游之應用至關重要。添加奈米碳管及石墨烯以為複合材料之後端表現端視於是否能均一性地將此些奈米材料分散至其一級結構以期充分發揮其性能。後續，吾人進一步利用離子交換反應亦或非共價鍵方式製造奈米混摻材料，如：將奈米銀粒子修飾在奈米碳管及奈米白金粒子在石墨烯上。這篇論文將分別探討奈米材料之分散性、粒徑大小、粒徑分佈、電性及應用於染料敏化太陽能電池之效率探討。
本論文分為二部分，旨在研究奈米粒子如銀奈米粒子、二氧化鈦奈米粒子、白金奈米粒子及奈米碳材如奈米碳管及石墨烯之分散作用力及機制及其於染料敏化太陽能電池之應用。在第一部分，兩大類的功能性高分子被使用來作碳材之分散及評估。在第三章中，吾人提出分散奈米碳管及其原位還原奈米銀粒子以製備奈米銀粒子修飾於奈米碳管上之連續製程，此奈米混摻材料亦展現出低溫導電之性質；第四章描述合成具有不同官能基之功能性高分子以作石墨烯分散之機制探討。隨著聚乙烯醇之導入原本分散良好的石墨烯分散液中，可製備出具高導電度及尺寸安定度之石墨烯膜，同時亦藉以驗證所合成高分子分散劑之分散性能。水性聚氨酯的導入則能成功製備兼具導電度及可撓曲性質之導電膜。此外，利用此石墨烯分散之機制，吾人更進一步開發由天然石墨直接脫層為少層石墨烯之製程，能有效避免石墨烯表面結構的破壞以維持其優異特性及降低製備成本。第二部分中，吾人將此些奈米材料之分散液導入染料敏化太陽能電池中，以為奈米材料分散性及分散重要性之評估。第五章中利用均勻分散之二氧化鈦奈米粒子製備出可調控粒子尺寸及孔洞分布之功能性薄膜，並將之應用於染料敏化太陽能電池之工作電極上。第六章則講述利用高分子分散劑製備出白金粒子/石墨烯奈米混摻材料，並將之塗佈於導電玻璃上以為染料敏化太陽能電池之對電極使用。由於該白金粒子/石墨烯奈米混摻材料之均勻分散性，此對電極具有的高穿透度亦有利於背照式染料敏化太陽能電池使用。

關鍵字

高分子分散劑 ； 分散 ； 染料敏化太陽能電池 ； 奈米碳管 ； 石墨烯 ； 非共價鍵鍵結 ； 奈米材料 ； 背照式染料敏化太陽能電池

並列摘要

“Dispersion technology” is considered as the key step in bottom-up process for self-assemblies and fabricating nanomaterial devices. Herein, dispersion of sp2 carbon materials, graphene and carbon nanotube (CNT), in aqueous or organic mediums is important process for utilizing nanomaterials in various downstream applications. Further, the performance of adding CNT and 2D platelet-like graphene as the nanoscale fillers to nanocomposites relies on the step of homogeneously dispersing the nanomaterials into their primary structure. Nanohybrids including silver nanoparticles decorated on the carbon nanotube (CNT) and platinum-on-graphene were fabricated by ionic excharge reaction and non-covalent method. These materials were investigated on dispersibility, particle size and distribution, electrical behavior, and the applications for dye-sensitized solar cells (DSSCs).
There are two parts in this dissertation, aiming to investigate the dispersion of nanomaterials including nanoparticles such as silver nanoparticle (AgNP), titanium dioxide and platinum nanoparticle (PtNP), carbon materials such as carbon nanotube (CNT) and graphene and the sequential hybridization for the use in DSSCs. In the first part, two families of functional polymers for homogeneously dispersing CNT and graphene in aqueous medium were reported. The tandem procedures of dispersing CNT and then AgNPs were developed to prepare CNT-tethered AgNPs nanohybrids, which allowed the conductive application at low temperature (Chapter 3); the structural differences in chemical functionalities of the synthesized polymers were allowed to evaluate their ability for dispersing graphene by disrupting the π-π stacking aggregation. With the assistance of adding polyvinyl alcohol, the homogeneously dispersed graphene in water was fabricated into a dimensionally stable film exhibiting high conductivity, evidenced the dispersing ability of the synthesized oligomers as the polymeric dispersants. With the introduction of waterborne polyurethane, conductive and flexible graphene films were prepared. In addition, by utilizing the dispersing mechanism of graphene, graphene directly exfoliated from graphite was realized, and that prevents the inevitable structural defects and lowers the cost of graphene preparation (Chapter 4). In the second part, dispersion of nanomaterials applied on DSSCs was exploited to assess the dispersibility and the importance of dispersion. The dispersion of TiO2 nanoparticles to generate the functional films effectively allows the control of TiO2 particle size and pore size distribution in film matrix for suitable uses as photoanodes in DSSCs (Chapter 5). A dispersion of platinum-on-graphene was prepared in the presence of a polymeric dispersant and subsequent in-situ reduction of dihydrogen hexachloroplatinate to metallic platinum on the graphene surface. The platinum-on-graphene dispersion was coated on an FTO glass to prepare a counter electrode (CE) for a DSSC. The hybrid film of platinum nanoparticles and graphene nanoplatelets (PtNP/GN) showed a transparency of 70% at 550 nm, indicating its suitability as a CE material for a rear-illuminated DSSC (Chapter 6).

並列關鍵字

Polymeric dispersant ； Dispersion ； Dye-sensitized solar cell ； Carbon nanotubes ； Graphene ； Noncovalent interactions ； Nanomaterials ； Rear-illuminated dye-sensitized solar cell

參考文獻

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