新型聚(胺-醯亞胺)薄膜之光電性質及其與PEDOT搭配之電致色變元件研究

Study on the Electro-optical Properties of a Novel Poly(amine-imide) Film and Its Electrochromic Devices Assembled with PEDOT

顏翠玲(Tsui-Ling Yen)

指導教授 ： 何國川

國立臺灣大學/工學院/高分子科學與工程學研究所/碩士(2006年)

https://doi.org/10.6342/NTU.2006.10257

摘要

本論文針對一新型聚(胺-醯亞胺)薄膜之光電性質及其與導電高分子poly(3,4-ethylenedioxythiophene) (PEDOT)搭配之電致色變元件進行探討。其中，此新型高分子是由N,N-bis(4-aminophenyl)-N’,N’-diphenyl-1,4-phenylenediamine 以及3,3’,4,4’-benzophenonetera carboxylic dianhydride 兩個單體所聚合而成，並直接取得自國立暨南國際大學應用化學系劉貴生教授之實驗室，而為了方便描述此高分子便將其命名為Poly(PD-BCD)。

於薄膜的特性分析上，分別利用循環伏安法以及階梯電位操作對兩薄膜進行電化學及光學量測。其中，當Poly(PD-BCD)的電位操作於第一段反應區間內時，不論是光學或是電化學穩定性都比第二段反應區間之表現好，然而，第一段反應區間之著色效率值為48.32 cm2/C (λ=624nm)比起第二段反應區間的著色效率值316.06 cm2/C (λ=624nm)低的許多，因此，考量穩定性以及穿透度變化，應適當選擇Poly(PD-BCD)薄膜的操作電位窗範圍，以使其表現達最佳狀態。而另一薄膜電極PEDOT，當其電位操作於0.3V以及-1.0V區間時，著色效率值大約為178.06 cm2/C (λ=624nm)。

由於Poly(PD-BCD)為一新型高分子，因此為了瞭解Poly(PD-BCD)於不同的操作電位下，陰、陽離子以及溶劑分子進出薄膜的情形，本研究利用電化學微量石英震盪天秤(EQCM)對其進行質量之特性分析，並進一步對此電致色變材料提出其氧化還原機制。由於Poly(PD-BCD)在進行氧化時會形成Poly(PD-BCD)+·或是Poly(PD-BCD)+2的狀態，因此，為了維持電中性的條件，陰離子勢必會進入膜內以中和電性，所以於EQCM數據分析方面，兩段反應皆應考慮陰離子對薄膜質量變化的貢獻。在陽離子的考量方面，當Poly(PD-BCD)於含有不同陽離子之電解質液下(如LiClO4、NaClO4以及TBAClO4)進行掃描時，經由CV以及EQCM所得之數據，可以發現Poly(PD-BCD)之第一個反應區段所表現的Δm-q斜率值皆不相同，因此，除了陰離子之外，陽離子也會參與Poly(PD-BCD)的第一段反應。而於第二個反應區段中此薄膜電極所表現的Δm-q斜率值卻幾乎相同，表示陽離子效應對於Poly(PD-BCD)的第二段反應的影響是較不明顯的。經由上述之實驗結果，本研究針對兩個反應區段分別提出了不同的氧化還原反應式。

於元件的組裝上，首先利用Poly(PD-BCD)薄膜的第一個氧化還原反應區段 (0.1 ~ 0.6 V；q rxn 10 mC)搭配PEDOT (0.3 ~ -1.0 V；q rxn 10 mC)組裝成ECDI，其中，ECDI所表現的ΔT624大約為43.06%。有鑑於Poly(PD-BCD)薄膜之電位窗跨越至第二段反應區時，其穿透度變化會大幅提升，因此本研究選擇Poly(PD-BCD)的第一個反應區段和部份第二反應區段(0.1 ~ 0.8 V；q rxn 10 mC)與PEDOT (0.3 ~ -1.0 V；q rxn 10 mC)搭配組裝成ECDII，以試著提高元件之穿透度變化，而ECDII之ΔT624大約為44.85%左右。其中，兩元件於去色態時為淡藍色，著色態則為深藍色。然而，由於元件之光學表現會同時受到兩薄膜電位分布以及薄膜本身特性的影響，因此由電位分布之方法可知雖然ECDII內的Poly(PD-BCD)薄膜電位窗已跨越至第二段反應區，但是為了使元件內兩薄膜之電量能以一比一搭配，因此，在組裝ECDII時，製備Poly(PD-BCD)薄膜的鍍液濃度會先經過稀釋，不過卻也使Poly(PD-BCD)薄膜可提供的著色態穿透度受到限制，再加上ECDII內PEDOT的反應電位窗有縮減的趨勢(相較於ECDI內之PEDOT薄膜)，因而使得PEDOT薄膜可提供的穿透度變化有限，所以ECDII穿透度差值的提升幅度並不明顯。

關鍵字

電致色變元件 ； EQCM ； 離子傳輸 ； PEDOT ； 聚(胺-醯亞胺) ； 氧化還原反應機制

並列摘要

The electro-optical properties of a poly(amine-imide) film and its electrochromic device assembled with poly(3,4-ethylenedioxythiophene) (PEDOT) have been studied in this study. The novel poly(amine-imide) film obtained from the lab. of Prof. Guey-Sheng Liou, Dept. of Applied Chemistry, National Chi Nan University, was synthesized with N,N-bis(4-aminophenyl)-N’,N’-diphenyl-1,4-phenylenediamine and 3,3’,4,4’-benzo-phenonetera carboxylic dianhydride, and the polymer was abbreviated as Poly(PD-BCD).

With cyclic voltammetry and potential step method, the electrochemical and optical properties of both films were investigated. For Poly(PD-BCD), the first redox stage showed higher electrochemical and optical stabilities than those of the second stage. However, the coloration efficiency of the first stage is 48.32 cm2/C (λ=624nm), which is lower than that of the second one, 316.06 cm2/C (λ=624nm). In order to optimize the optical and electrochemical properties of Poly(PD-BCD) electrode, the potential windows must be chosen properly. As for the other PEDOT thin film, the coloration efficiency is 178.06 cm2/C (λ=624nm) when the voltages were applied from 0.3 to -1.0 V.

The mass change of Poly(PD-BCD) was studied by an EQCM, including the transport of anions, cations and solvent into and out of the polymer matrix upon different applied voltages. The reaction mechanism of Poly(PD-BCD) has been proposed. Since the polymer chain possessed positive charge when Poly(PD-BCD) was oxidized to its radical cation state or dication state, the anions would insert into the polymer matrix in order to neutralize the charge, thus the contributions of anions should be taken into account toward the mass change for both reaction stages. However, when the electrodes were cycled in electrolytes containing different cations (such as LiClO4, NaClO4 and TBAClO4), the experimental results revealed different mechanisms for both reaction stages. The slopes of Δm-q obtained from the CV-EQCM measurements in three electrolytes were different for the first redox stage. This means that in addition to the involvement of anions, cations also play an important role in the first redox stage. However, the slopes of Δm-q were almost the same for the second redox stage. This reveals that cations play significantly less role in the second stage. Thus, different reaction mechanisms for the two reaction stages of Poly(PD-BCD) were proposed in this study.

Utilize the first redox reaction region of the Poly(PD-BCD) film (0.1 ~ 0.6 V；q rxn 10 mC) in conjunction with PEDOT film (0.3 ~ -1.0 V；q rxn 10 mC) to form ECDI which showed ΔT624 is 43.06%. As the operated potential of Poly(PD-BCD) film was extended to the second redox region, the transmittance attenuation of the electrode would be enlarged. In order to increase the transmittance attenuation of the devices, another reaction region of Poly(PD-BCD) (0.1 ~ 0.8 V；q rxn 10 mC) was selected to construct ECDII containing a PEDOT thin film (0.3 ~ -1.0 V；q rxn 10 mC), and ECDII achieved ΔT624 of 44.85%. Moreover, both devices showed light blue at the bleached state and deep blue at the colored state. However, the optical properties of the devices would be affected by the potential distribution and the intrinsic electro-optical properties on both films. Even when the potential window of the Poly(PD-BCD) in ECDII was extended to the second redox reaction region, the increase in the transmittance attenuation of ECDII was not obvious. It was due to that the polymer solution in forming the Poly(PD-BCD) film was diluted and the potential distribution of PEDOT film was decreased upon the operated potential of ECDII. Both reasons would restrain the transmittance attenuation of ECDII.

並列關鍵字

Electrochromic device ； EQCM ； ionic transport ； PEDOT ； Poly(amine-imide) ； redox reaction mechanis

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