کد مقاله | کد نشریه | سال انتشار | مقاله انگلیسی | نسخه تمام متن |
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1497664 | 993027 | 2007 | 6 صفحه PDF | دانلود رایگان |
Electrochromic devices (ECDs) are electrochemical cells with one or two electrochemically active coatings that change color during the reduction–oxidation process. In this work an electrochromic polyaniline (PANI) thin film and a viscous electrolyte, formed by mixing a basic aqueous solution of polyethylenimine (PEI) and concentrated sulfuric acid (H2SO4), have been used as the main components of an ECD. The pH value of the electrolyte is a function of the relative proportion between PEI and H2SO4. Fourier transform infrared spectroscopy (FT-IR) results show that for those PEI–H2SO4 complexes of pH value varied from 2 to 9 sulfate ions of the inorganic acid are associated to the imine groups of PEI. If the pH value of the same system is lower than or equal to 1, HSO4- anions appear in the electrolyte together with a notable reduction of the free water content. Electrochemical impedance spectroscopy study of these electrolytes show that the protonic conductivity of the PEI–H2SO4 complex with pH 1 is almost three orders of magnitude lower than that of the same electrolytes but with a pH value between 2 and 6. Optical switch speed of a PANI/PEI–H2SO4 based ECD at 550 nm under a square potential application of +1.2 V and −1.2 V is proportional to the ionic conductivity of the electrolyte of the device.
Journal: Optical Materials - Volume 29, Issue 6, February 2007, Pages 579–584