- 學位論文
以PEDOT-Cl或PProDOT-Et2與InHCF構成之互補式電致色變元件
Complementary Electrochromic Devices Based on PEDOT-Cl or PProDOT-Et2 and InHCF
摘要
本論文透過結合改質過的導電高分子或其衍生物(PEDOT-Cl or PProDOT-Et2)與新製程所製備出可分散於水相之無機普魯士藍類似物六氰鐵化銦(InHCF)所搭配，組成兩個新的互補式電致色變系統。由於液態電解質之電致色變元件於長期穩定性的測試下，往往無法避免漏液的問題，因此為了改善元件之長期穩定性，導入膠態電解質(PMMA gel electrolyte)於光電性質較好的PProDOT-Et2/InHCF之系統中進行研究，預期可有效改善漏液問題，並探討此元件分別於室溫及50 oC不同溫度下之光學長期穩定性。發展此一系統之主要動機在於對電極於可見光區之光學變化小，呈現顏色近乎透明，故可透過此搭配方式使陰極著色材料充分呈現出其光學變化。本研究利用循環伏安法、階梯電位及同步紫外光/可見光光譜，分析薄膜單及與元件之電致色變性質。 第四章為兩種陰極著色材料之單膜性質分析，其中透過在水相電聚合導電高分子poly(3,4-ethylenedioxythiophene) (PEDOT)的過程中添加具有強陰電性之氯離子(Cl-)當作電解質，意外得到具有不同於以往光學性質的導電高分子PEDOT(簡稱PEDOT-Cl)，分別呈現紅棕色及淡藍色的顏色轉換在其還原態與氧化態，有別於文獻中提及的深藍色與淺藍色之顏色變化。有鑑於其光學變化過程中無透明態，導致其單膜之穿透度變化受限僅30%，故引入具高光學對比poly(3,3-diethyl-3,4-dihydro-2H-thieno-[3,4-b][1,4]dioxepine) (簡稱PProDOT-Et2) 之導電高分子於本研究中，以改善元件於可見光區之表現。此外，針對PEDOT-Cl這新材料亦使用了EQCM去觀察此薄膜於氧化還原反應過程之離子進出情形，且由結果可總結出PEDOT-Cl薄膜與PEDOT皆屬陰離子主宰之電致色變材料。 第五章為陽極著色材料InHCF之材料分析及單膜性質探討，首先從文獻可知Kurihara’s group於2007年製備出水溶性普魯士藍奈米粒子，藉由參考其反應物之配方可製備出水溶性六氰鐵化銦奈米粒子，鑑定結構部分先透過X光繞射儀並與文獻交叉比對判斷此透過新製程方式所合成出之六氰鐵化銦晶格排列是與一般透過電鍍方式得到之產物相同，且進一步使用掃描式電子顯微鏡觀察其顆粒確認是其大小為奈米尺寸。再以循環伏安法、階梯電位及同步紫外光/可見光光譜了解薄膜之光電性質，並應用於電致色變系統之對電極擔任離子儲存層。 在了解單膜之電致色變特性之後，第六章將分別對於PEDOT-Cl/InHCF及PProDOT-ET2/InHCF電致色變元件進行一系列基礎電致色變性質的分析。同步紫外光/可見光光譜之吸收度光譜的結果分別呈現出其最敏感的光學吸收度發生於波長500 nm及590 nm，與其在單膜之結果相同，這結果說明了InHCF薄膜並未對光學性質有所貢獻。在PEDOT-Cl/InHCF系統中，操作於-0.1 ~ -1.4 V之電位窗下，可觀察其光學端透度變化為23.3%，著、去色時間分別為，2.7及2.5秒且其著色效率為570.7 cm2/C；然而在PProDOT-Et2/InHCF系統中，操作在0.5 ~ -0.9 V之電位窗下，可觀察其穿透度變化為44.7%，而著、去色時間分別是1.6及1.8秒且其著色效率為941.5 cm2/C。兩系統相較下可知PProDOT-Et2/InHCF系統具有較大的光學調幅、較快的想應時間及較高的著色效率。故特將此系統引入PMMA膠態電解質並探討不同溫度下對元件之光學長期穩定性之影響：於液態電解質的條件下所組成之元件於常溫下連續操作10,000圈，其穿透度變化從原先的41.3%減少至36.7%，保有起始穿透度的89%；而將液態電解質所組成之元件於50 oC條件下連續操作10,000圈後，其穿透度變化則是由起始的39.1%降低至32.8%，僅維持原先的84%；而在引入膠態電解質所組成之元件，於常溫條件下連續操作10,000圈，其穿透度變化則是由51.9%遞減為46.0%，與其起始的穿透度相比保持有89%，這結果說明PMMA為主體的膠態電解質不僅可改善液態電解質漏液之問題，更可提升元件之光學性質。
並列摘要
In this work, the complementary electrochromic devices (ECDs) were assembled by using modified conducting polymer (PEDOT-Cl) or its derivative (PProDOT-Et2) and a water-soluble Prussian blue analog, indium hexacyanoferrate (InHCF). For a liquid electrolyte-based ECD, leakage of electrolyte is a serious problem in the long-term stability test; therefore, we replaced the liquid electrolyte by PMMA gel electrolyte to improve its stability. Owing to the optical property of the PProDOT-Et2/InHCF ECD is better than that of the PEDOT-Cl/InHCF, the former system was studied using the PMMA gel electrolyte and investigated the stability of the ECD at room temperature (R.T.) and 50 oC. The main motivation to develop these two ECDs is that the optical density change of the counter electrode (InHCF) is small and the color change in the visible region is nearly transparent; therefore, all the optical density change was contributed from the cathodically coloring material. In this study, the electrochromic (EC) properties of thin films and devices were analyzed by cyclic voltammetry, potential step, and in-situ UV-Vis spectrophotometry. Two cathodically coloring materials were chosen in this study and will be discussed in Chapter 4. One was accidently obtained by adding chloride ions with strong nucleophilicity as the supporting electrolyte during electro-deposition of poly(3,4-ethylenedioxythiophene) (PEDOT), which is named PEDOT-Cl. This material exhibited light blue and red brown at the oxidized state and reduced state, respectively. Normally, the pristine PEDOT thin film can be switched between deep blue and light blue; however, the phenomenon we observed here is dramatically different from what have been reported in literatures. Since PEDOT-Cl has no transparent state in both the reduced state and the oxidized state, the obtained transmittance change of the film was only 30%. Therefore, we chose a high transmittance change conducting polymer, (poly(3,3-diethyl-3,4-dihydro-2H-thieno-[3,4-b][1,4]dioxepine), or PProDOT-Et2, thin film as the complementary cathodically coloring material in this study. Furthermore, electrochemical quartz crystal microbalance (EQCM) was used to observe the ionic transportation in a PEDOT-Cl thin film during the redox reactions and the results concluded that the PEDOT-Cl was an anion-dominant EC material, which is the same as that of the PEDOT. The analyses of anodically coloring indium hexacyanoferrate (InHCF) and its electrochemical properties will be discussed in Chapter 5. At first, we take the recipe from Kurihara’s group as reference to prepare the water-soluble InHCF nanoparticle ink. According to XRD analysis, the lattice of InHCF was found to be identical to what reported in the literature in which InHCF was synthesized by electro-deposition. In addition, the images of SEM show that the particle size is in nano scale. The EC properties of thin films were analyzed by cyclic voltammetry, potential step, and in-situ UV-Vis spectrophotometry. We focused on the EC performance of both PEDOT-Cl/InHCF ECD and PProDOT-Et2/InHCF ECD, with the maximum absorption wavelength at 500 and 590 nm, respectively, implying that the InHCF had little contribution to the device’s optical response. In the PEDOT-Cl/InHCF ECD, the transmittance change (∆T) was 23.3% under the potential bias of -0.1 ~ -1.4 V and the response times for coloring and bleaching was 2.7 and 2.5 s, respectively. Also the coloration efficiency can be calculated to be 570.7 cm2/C at 500 nm. In contrast, in the PProDOT-Et2/InHCF ECD, the ∆T was 44.7% under the operating potential bias of 0.5 ~ -0.9 V and the response times for coloring and bleaching was 1.6 and 1.8 s, respectively. The coloration efficiency was calculated to be 941.5 cm2/C at 590 nm. By comparing these two ECDs, we found that the PProDOT-Et2/InHCF ECD possessed better EC properties, including larger optical contrast, faster response times and higher coloration efficiency. We further investigated the temperature effect and its long-term stability by using PMMA gel electrolyte. For the case of liquid electrolyte and switching at R.T., the ∆T still remained 89% of its original value after 10,000 continuous cyclings, namely, the ∆T value decreased from 41.3% to 36.7%. For the case of liquid electrolyte and switching at 50 oC, the ∆T value decreased from 39.1% to 32.8% and only remained 84% of its original value for 10,000 continuous cyclings. For the case of gel electrolyte and switching at 50 oC, the ∆T also remained 89% of its original value after 10,000 continuous cyclings. That is, the ∆T value decreased from 51.9% to 46.0%, implying that the PMMA gel electrolyte not only can solve the problem of electrolyte leakage but also can improve the optical performance of the ECD.