Dresden 2020 – scientific programme
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O: Fachverband Oberflächenphysik
O 84: Poster Session - Solid-Liquid Interfaces: Reactions and Electrochemisty
O 84.1: Poster
Wednesday, March 18, 2020, 18:15–20:00, P2/EG
Water-Based Electrolytes and Porous Tungsten Oxide in Electrochromic Cells — •Florian Eberheim, Thi Hai Quyen Nguyen, and Derck Schlettwein — Justus Liebig University Gießen, Institute of Applied Physics
Sputter-deposited tungsten oxide (WO3) is commercially applied in light-managing devices (smart windows). The aim of this work consists in the preparation of porous WO3 films and in the measurement of their electrochromic characteristics in contact to aqueous LiCl, NaCl, KCl and H2SO4 as alternatives to the established Li+-containing organic electrolytes. The films were prepared by spin-coating a precursor solution with poly(ethylene glycole) (PEG) of different molecular weight as additives and subsequent heating on a hot-plate at 250∘C. Amorphous WO3 was formed, shown by SEM and EDX. The transparent films were characterized by cyclic voltammetry and chrono-amperometry while optical transmission was simultaneously monitored. It was shown that the films prepared with PEG as additive showed improved contrast of transmission compared to films prepared without additives. The water-based electrolytes led to the same blue coloration as the films in contact to Li+. Electrolytes with protons as ions reached the best coloration characteristics, but led to faster degradation of the films. It was shown in this study that porous WO3 films reversibly switch their optical transmission by intercalation of ions from water-based electrolytes. Such combinations could be a healthy and inexpensive alternative to the established state-of-the art.