| Summary: | 碩士 === 國立臺灣大學 === 高分子科學與工程學研究所 === 94 === 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.
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