靜電紡絲在電池材料的應用研究 (1)銦錫氧化物（ITO）導電纖維之製備 (2)TiO2及其前驅物混層薄膜的製備

Application of Electrospinning in Photovoltaic Cell (1)Preparation of ITO Fibre (2)Preparation of a Hybrid Layer of TiO2 and its Precursor

林若純(Jo-Chun Lin)

指導教授 ： 趙豫州

國立臺北科技大學/工程學院/工程科技研究所/博士(2013年)

https://doi.org/10.6841/NTUT.2013.00558

摘要

(1)銦錫氧化物（ITO）導電纖維之製備
熔融紡絲、液體結晶紡絲和膠體紡絲等纖維直徑一般為5∼500μm，但由靜電紡絲所製備出的纖維直徑是大約3 nm至5μm，因此靜電紡絲被視為製造奈米纖維的基本方法。靜電紡絲是施加電場於聚合物溶液使其成為纖維的技術。靜電紡絲技術可用於包括聚酯尼龍與聚乙酸乙烯酯等多種聚合物材料上。
透明導電氧化物（TCO），如銦錫氧化物（ITO）中可應用於平板顯示器、太陽能電池以及發光二極管。 ITO作為透明導電電極有其獨特的性能，例如高透光率、低電阻率的和良好的基板的吸附性。ITO一般薄膜的製備，採用沉積技術，如脈衝激光沉積的溶膠-凝膠浸/旋塗、磁控濺射法和噴霧熱解法等。脈衝激光沉積的溶膠-凝膠浸/旋塗其缺點在於基板需經過高溫熱處理，膜薄厚度與均勻性不易控制等。磁控濺射法其主要缺點是所需設備價格高，且需要高壓或大功率直流電源。噴霧熱解法其缺點是制得的ITO薄膜品質不高，性能不穩定，且鹽類噴霧熱分解過程很複雜。本研究使用溶凝膠之靜電紡絲技術製備纖維以改善上述缺失。ITO與聚氧化乙烯(PEO)的重量比為8.5:1.5時可製得導電度可達1000Ω/□的奈米纖維。

(2)TiO2及其前驅物混層薄膜的製備
過去的二十年來，染料敏化太陽能電池（DSSC)因製程簡易和環境污染低，已被廣泛的研究。大多數染料敏化太陽能電池採用二氧化鈦的奈米半導體材料，作為電子傳輸介質，染料敏化劑因光照而激發電子並轉移到二氧化鈦通過外部電路使一個工作電極和對電極，分別在電解質的存在下形成太陽能電池。重要的是，太陽能電池的染料要盡可能吸收較多光子以產生更多的電子。以便在相同的光電流下可使用較薄的薄膜，以及增加與電解質的還原效率。較薄的太陽能電池，可抑制載流子複合，並減少內部電阻，因此染料敏化太陽能電池是使用奈米二氧化鈦薄膜以具有較高的比表面積，以及具有較好的光散射層（400-500 nm厚的二氧化鈦薄膜）以增加電池的效能。雖然小尺寸的奈米TiO2（粒徑約20 nm）薄膜，可確保高表面積，但光散射較傳統的奈米TiO2薄膜為差，因此文獻報導將其與大顆粒的TiO2上下疊層以提高光的散射與光的路徑。但需塗佈兩次且層與層間容易會有暗電流產生。若將兩者混和均勻，再用價格低廉的靜電紡絲設備製造TiO2電極，不僅可以簡化製程更可以減少暗電流的產生，而提高效率。本研究係以混合大小尺寸的TiO2並以靜電紡絲製造TiO2電極，其效率較傳統的電池佳。以靜電紡絲來製造染料敏化太陽能電池(DSSC)不但可以簡化製程及降低製作成本，而且能提升染料敏化太陽能電池的競爭力。

關鍵字

銦錫氧化物 ； 靜電紡絲 ； 導電纖維 ； 染料敏化太陽能電池

並列摘要

(1) Preparation of ITO fibre
Melted spinning, liquid crystallized spinning and colloidal spinning is generally between 5 to 500μm. The diameter of a fibre made by any traditional method such as, whereas the diameter of fibre made by electrospinning is roughly between 3 nm to 5μm. Electrospinning is regarded as the essential fundamental method for manufacturing nanometer fibres. Electrospinning is the technology of making polymer fibres by applying electric field to a polymer solution. The electrospinning technology is utilized in multiple polymer materials including nylon and polyvinyl acetate. ITO is a transparent conducting electrode because of its unique properties of high transmittance, low resistivity and excellent adhesion to substrates. This studied is used a sol-gel composition for producing conductive fibres in an electrospinning process. The sol-gel composition comprises an indium tin oxide and a polyethylene oxide; wherein they are mixed in a ratio of about 8.5:1.5 (w/w) that conductivity is 1000Ω/□。

(2) Preparation of a hybrid layer of TiO2 and its precursor
In a solar cell system, it is important that the active layer of the solar cell absorbs as many photons as possible to produce more carrier electrons. In other words, the same photocurrent may be produced with a thinner film, and additional enhancement is also expected in thinner solar cells owing to the suppressed carrier recombination and decreased internal resistance. The essential requirement for the production of DSSC modules is to produce thin nanocrystalline TiO2 films with higher surface area, together with a better light scattering layer (400-500 nm sized TiO2), so that the production cost can be reduced by lowering the dye consumption without sacrificing the cell performance. Although the small size of the TiO2 nanoparticles (∼20 nm) employed to ensure a high surface area makes conventional nanocrystalline TiO2 films as poor light scatters, mixing the nanoparticles with larger particles or applying a scattering layer to the nanocrystalline film has been shown in simulations and increase of light harvesting by enhancing the scattering of light is feasible. The efficiency of hybrid TiO2 film by P25 and titanium tetraisopropoxide is better than that of P25 and that of two layers made by P25 and titanium tetraisopropoxide respectively. Besides that, hybrid TiO2 film can be made by electrospinning, less time and lower production cost. We believe the simple and cheap merit of electrospinning will have wide application in DSSC and help then move quickly to commercialisation.

並列關鍵字

electrospinning ； indium tin oxide ； fibre ； DSSC

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