On the Electro-Optical Properties of PDMICA Thin Film and Its Application to Electrochromic Devices
Date Issued
2012
Date
2012
Author(s)
Tseng, Chen-Ya
Abstract
In this research, the main objective is to analyze the electrochemical properties of a novel conducting polymer, poly(5,6-dimethoxyindole-2-carboxylic acid) (PDMICA), and its electrochromic device assembled with poly(3,4-ethylenedioxythiophene) (PEDOT).
In the first part (Chapter 4), the transport phenomena of anions, cations, and water molecules through the film of PDMICA was studied in the electrolytes of LiTFSI, LiNO3, LiI, and NaNO3, by means of electrochemical quartz crystal microbalance (EQCM), intending to throw more light on its electrochromic behavior. Cations do not affect the ion transport, but anions play an important role during the reduction and oxidation of the film. The molar fluxes of anions and water molecules in the film of PDMICA were estimated for LiTFSI and LiNO3. Besides, the number of accompanying water molecules with TFSI- and NO3-, during the redox switching of PDMICA in LiTFSI and LiNO3 were calculated to be 14.7 and 3.4 per TFSI- and NO3-, respectively.
In the second part (Chapter 4 and Chapter 5), PDMICA is prepared by electro-polymerization and investigated using in situ spectro-electrochemical analyses, including cyclic voltammertry (CV) and UV-visible (UV-vis) spectroscopy. A significant change from transparent (-0.5 V vs. Ag/AgCl) to green (0.5 V vs. Ag/AgCl) and a reversible electrochromic behavior of PDMICA film are observed when the film is performed in an aqueous solution consisting of 0.1 M lithium bis(trifluoromethanesulfonyl)imide (LiTFSI) and 1.0 mM hydrochloric acid (HCl). The maximum transmittance change (∆T) and the coloration efficiency (η) of PDMICA film are 15% and 73 cm2/C, respectively, at 520 nm. The PDMICA thin film and a thin film of PEDOT are chosen as an anode and a cathode, respectively, in a complementary manner to form a film-type electrochromic device (ECD). A remarkable absorbance attenuation of this ECD is observed in the visible region. The maximum ∆T of the ECD gives a value of 39% (@583 nm) when the applied potential for the device is switched between -0.5 and 1.0 V (PDMICA vs. PEDOT); the η of this ECD is estimated to be 372 cm2/C at 583 nm.
Subjects
Coloration efficiency
electrochromic
electrochemical quartz crystal microbalance
ion transport
poly(5,6-dimethoxyindole-2-carboxylic acid)
Type
thesis
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