Preparation and characterization of polymer-based electrochromic films

In this study, electrochromic, optical and structural characterization of polypyrrole (PPy) films and polypyrrole/nanocellulose (PPy/NC) nanocomposite films, were used to determine the properties of the films in the three-electrode cell by using two different salts, tetrabutylammonium perchlorate (TBAP) ve 4,5-dihydroxy-1,3-benzenedisulfonate (Tiron). During the initial phase of this study suitable coating method and salt were sought in order to produce stable and uniform films. With the electrochemical method called as potentiostatic coating all film coatings were made at a constant potential of 1.2 V. TBAP salt, soluble in acetonitrile (ACN), was used first. At the same time, ACN has been found suitable as a solvent in terms of dispersing pyrrole in solution. Since the Tirone salt is not soluble in ACN, a solution with ratio of 0.1 M 6:4 ACN:deionized water (ACN:DI) was prepared in order to dissolve both the Tirone and the pyrrole. The amount of pyrrole in the coating solutions was kept constant as 0.1 M. New solution was prepared for each measurement. All films are coated on conductive and transparent Fluorine doped Indium Tin Oxide (FTO) glass in order to manage the coating and see the color change. Cyclic voltammetry (CV) and chronoamperometry (CA) measurements were made within the scope of electrochemical measurements. As a result of the measurements, information such as characteristic CV curves, stability, response time and charge density of electrochromic films were obtained. Transmittance of PPy (TBAP), PPy (Tiron), PPy/NC (TBAP) and PPy/NC (Tiron) electrochromic films were measured in the UV/Visible region. Films exhibiting petroleum green color in the oxidation state were found to exhibit light yellow color in the case of reduction. Structural characterization of electrochromic films was made by scanning electron microscopy (SEM). In this way we compared structural effects of different salts and the NC effect on film properties. Electrochromic films were coated electrochemically at Analytical Chemistry Laboratory within at Department of Molecular Biology and Genetics, Istanbul University. The transmittance measurements of electrochromic films has been examined at Electrochemical Characterization and Measurement Laboratory, Istanbul Technical University. Structural analysis of all electrochromic films was carried out at Nano and Optoelectronics Research Laboratory at Physics Department, Istanbul University.