title: A redox-flow electrochromic window.
abstract: A low-cost electrochromic (EC) window based on a redox-flow system that does not require expensive transparent conductive oxide (TCO) substrates is introduced and demonstrated for the first time. An aqueous I3–/I– redox electrolyte is used in place of a TCO to oxidize/reduce a molecular layer of an EC triphenylamine derivative that is anchored to a mesoporous TiO2 scaffold on the inner faces of a double-paned window. The redox electrolyte is electrochemically oxidized/reduced in an external two-compartment cell and circulated through the window cavity using an inexpensive peristaltic pump, resulting in coloration or decoloration of the window due to reaction of the redox solution with the triphenylamine derivative. The absorption characteristics, coloration/decoloration times, and cycling stability of the prototype EC window are evaluated, and prospects for further development are discussed.
authors.affiliation: Department of Materials Science and Engineering, Faculty of Engineering, NUSNNI-Nanocore, National University of Singapore , 117576 Singapore.
authors.forename: James R
authors.initials: JR
authors.lastname: Jennings
authors.forename: Wei Yang
authors.initials: WY
authors.lastname: Lim
authors.forename: Shaik M
authors.initials: SM
authors.lastname: Zakeeruddin
authors.forename: Michael
authors.initials: M
authors.lastname: Grätzel
authors.forename: Qing
authors.initials: Q
authors.lastname: Wang
keywords: electrochromism; ioidide/triiodide; redox-flow; smart windows; titanium dioxide; triphenylamine