含紫精與高分子電解質之新穎電致色變元件

Novel Electrochromic Devices Composed of Viologens and Polymer Electrolytes

呂昕則(Hsin-Che Lu)

指導教授 ： 何國川

國立臺灣大學/工學院/化學工程學研究所/碩士(2016年)

https://doi.org/10.6342/NTU201600341

摘要

本論文探討以兩種含有新穎紫精之電致色變元件之表現，包括二乙烯苯基紫精以及二壬基紫精，並以控制此兩元件之膠態電解質之聚合程度以探討其對於紫精固化的能力。本論文中提出兩種不同之方法來探討膠態電解質固化紫精之現象，並連結電致色變元件之表現、膠態電解質之固化程度、以及電解質中氧化還原對之質傳系數之間的關係。
首先為了探討紫精固化對於其電致色變元件之影響，本論文中合成了二乙烯苯基紫精並應於電致色變元件，二乙烯苯基紫精上可聚合之乙烯基將可使其在紫外光固化下自我固定。本論文中，藉由同時通過一電位差以及紫外光線於電致色變元件，二乙烯苯基紫精將被固定在電極上並與高分子電解質鍵結。本論文中提出含有氧化著色的普魯士藍、作為氧化還原對的二茂鐵、以及還原著色之固化二乙烯苯基紫精的電致色變元件。藉由使用高分子電解質、二茂鐵、以及固化二乙烯苯基紫精，此電致色變元件在40 s之紫外光固化下，表現出最好的長期穩定性。此元件在1.2 V以及-0.8 V來回操作時具有60.6%之光學穿透度變化，短的著去色響應時間(1.32 s去色時間、2.13 s著色時間)，以及在10,000圈後仍保持其最初86.5%之光學穿透度變化。本章節探討之元件也同時具備相較於其他含紫精的電致色變元件獨特的著去色效應，其具備可操控的多重電致色便特性。此外在本章節討論的元件中，透過Cottrell方程式也計算得到氧化還原對的質傳系數，並藉由質傳系數之變化，建立了其與高分子電解質聚合程度的關係，藉此高分子電解質聚合程度對於電致色變元件表現的影響也被證實。
在本論文中之另一章節探討了以不同紫精為基準之三種電致色變元件，其中分別含有二庚基紫精、二辛基紫精、以及二壬基紫精，在此三元件中同時含有二茂鐵作為氧化還原對。於此三元件中，含有二壬基紫精之元件因其最低之操作所需能源，固具有最高之著色效率(36.2 cm2/C)，同時其在0 V以及1.2 V間操作時，也具有理想之光學穿透度變化(在605 nm 為60.6%)以及長期穩定性(4,000圈後穿透度變化為45.4%)。根據上述結果，此元件更進一步混入了具有不同聚合程度之紫外光聚合之高分子電解質，於此電解質中含有高分子化離子液體([1-烯丙基-3-甲基咪唑][雙三氟甲基磺醯基亞醯胺])以及紫外光聚合交聯劑(乙氧基化三羥甲基丙烷三丙烯酸酯)。藉由控制高分子化離子液體之重量百分比可得到具有不同聚合程度之高分子電解質，並在含有二壬基紫精之電致色變元件中，由於其對紫精的固化，對長期穩定性有正面影響。於元件中，在不同聚合程度下，紫精固化的程度經由計算氧化還原對之質傳系數而被評估。同時提升高分子化離子液體的重量百分比能夠有效降低元件之操作所需能源，其變化表現出與質傳系數的下降同樣的趨勢。在含有二壬基紫精之電致色變元件中，具有20 wt%之元件(20-PIL電致色變元件)具有大的光學穿透度變化(在605 nm下有55.2%)、短的著去色響應時間(2.13 s去色時間、2.10 s著色時間)、高著色效率(60.4和273.5(不考慮在穩態之電流) cm2/C)、以及良好之長期穩定性 (10,000圈後穿透度變化為53.8% (保持原本之97.5%).

關鍵字

電致色變元件 ； 紫精 ； 高分子化離子液體 ； 膠態電解質 ； 紫外光固化 ； 高分子電解質

並列摘要

In this thesis, we investigated the electrochromic (EC) performance of two novel viologens-based electrochromic devices (ECDs), including vinyl benzyl viologen (VBV) and nonyl viologen (NV) through controlling the curing degrees of the gel electrolytes, namely, the immobilization of viologens. Two different methods were used to examine this phenomena, thus enabling us to establish the relationship between the EC performance of the two novel viologens, curing degrees of the gel electrolytes, and the diffusion coefficients of redox species in the electrolytes.
Firstly, to study the influence of immobilization of viologens on their EC performance. A novel viologen, VBV, was synthesized and utilized in an ECD. The polymerizable vinyl moieties on VBV allows it to perform self-immobilization by UV-curing method. Immobilized VBV (I-VBV) was obtained on the electrode and grafted with polymer electrolyte through simultaneously applying UV irradiation and potential bias toward an ECD. The ECD (PB/Fc/I-VBV ECD) was fabricated in which ferrocene (Fc) acted as a redox mediator, while Prussian blue (PB) and I-VBV served as anodic and cathodic coloring materials, respectively. With the utilization of polymer electrolyte, Fc, and I-VBV, the proposed PB/Fc/I-VBV ECD with a UV-curing time of 40 s (PB/Fc/I-VBV-40) exhibits the best EC performance among different UV-curing times in terms of long-term stability. It gives 60.6% transmittance change (∆T%) at 615 nm initially when switched between 1.2 V and -0.8 V. Short bleaching and coloring times of 1.32 s and 2.13 s were observed respectively. Moreover, a good long-term stability was obtained, maintaining 86.5% of its original ∆T% after 10,000 cycles. The PB/Fc/I-VBV ECD also exhibits a unique memory characteristic among all viologens-based ECDs reported in literatures and allows a tunable multi-electrochromism. In addition, the diffusion coefficients (apparent diffusivities (Dapp)) of the redox species in PB/Fc/I-VBV ECD were calculated based on Cottrell equation, establishing a relation between the diffusion rates of VBV and curing degrees. Thus, the reasons attributed to different EC performance of PB/Fc/I-VBV ECD were verified.
In the second part, we investigated three kinds of viologens-based electrochromic device (ECD) (heptyl viologen (HV), octyl viologen (OV), and nonyl viologen (NV) utilizing ferrocene (Fc) as a redox mediator. Among them, NV-based ECD exhibits the highest coloration efficiency (36.2 cm2/C) owing to the lowest driving energy. Besides, switching between 0 and 1.2 V, NV-based ECD shows a desirable initial transmittance change (∆T% = 56.7% at 605 nm), and long-term stability (∆T% = 45.4% after 4,000 cycles). According to the result from the first part, we introduced an UV-cured polymer electrolyte and varied its curing degrees in the NV-based ECD. UV-cured polymer electrolyte containing polymeric ionic liquid (PIL, 1-allyl-3-methylimidazolium bis(trifluoromethylsulfonyl)imide) and ethoxylated trimethylolpropane triacrylate (ETPTA). By controlling the weight percentage of the PIL, different curing degrees of the polymer electrolytes were obtained and led to an improved stability of the NV-based ECD because of the immobilization of NV. This phenomena was evaluated by calculating the apparent diffusivities (Dapp) of the redox species in the NV-based ECD under various curing degrees. In addition, increasing the amount of PIL leads to a lower driven energy of NV-based ECD, following the same trend as the Dapp. Among all NV-based ECD, 20 wt% of PIL addition (20-PIL ECD) exhibits a large transmittance change (∆T% = 55.2% at 605 nm), short switching times (2.13 s in coloring process and 2.10 s in bleaching process), high coloration efficiency (60.4 and 273.5 (after excluding the current at steady-state) cm2/C), and exceptional cycling stability (∆T% = 53.8% after 10,000 cycles (97.5% remained)).

並列關鍵字

Electrochromic devices ； Viologens ； Polymeric ionic liquids ； Gel electrolytes ； UV-curing ； Polymer electrolytes

參考文獻

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