Regensburg 2022 – scientific programme
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O: Fachverband Oberflächenphysik
O 20: Poster Monday: Solid-Liquid Interfaces
O 20.5: Poster
Monday, September 5, 2022, 18:00–20:00, P4
Increase of the Spectroelectrochemical Performance of WO3 Films by Using Additives During Film Growth — •Thi Hai Quyen Nguyen1, Florian Eberheim1, Sophie Göbel1, Pascal Cop2, Marius Eckert1, Tim P. Schneider1, Lukas Gümbel1, Bernd M. Smarsly2, and Derck Schlettwein1 — 1Justus-Liebig-Universität Gießen, Institut für Angewandte Physik — 2Justus-Liebig-Universität Gießen, Physikalisch-Chemisches Institut
Tungsten oxide (WO3) is commonly used as an electrochromic material in smart windows. The electrochromic performance of WO3 is highly influenced by the mixed electronic and ionic transport in the film and, thus, by the accessibility of the internal film volume. In this work, WO3 thin films were prepared by spin-coating from a precursor solution based on peroxotungstic acid and different polymer additives such as polyethylene glycol (PEG), a block copolymer (PIB50−b−PEO45) and a combination thereof. The influence of the additives on the porosity and composition of WO3 was studied by, e.g., scanning electron microscopy, X-ray photoelectron spectroscopy and atomic emission spectroscopy. Electrochromic characteristics of the films were measured with LiClO4 in propylene carbonate as electrolyte. The intercalation of Li+ ions was analyzed by time-of-flight secondary ion mass spectrometry. The use of PEG provided microporous films leading to improved effective diffusion coefficients, transmittance modulations and response times compared to compact WO3. Further improved characteristics were obtained for films with interconnected mesopores prepared with PEG and PIB50−b−PEO45.