Thin Films of Antimony-Tin Oxide as Counter-Electrodes for Proton Working Electrochromic Devices
- PDF / 1,512,298 Bytes
- 6 Pages / 612 x 792 pts (letter) Page_size
- 40 Downloads / 206 Views
Thin Films of Antimony-Tin Oxide as Counter-Electrodes for Proton Working Electrochromic Devices N. Naghavi, C. Marcel, L. Dupont, A. Rougier and J-M. Tarascon Laboratoire de Réactivité et Chimie des Solides, Université de Picardie Jules Verne, 80039 Amiens Cedex. ABSTRACT We report here on thin films proton-working electrochromic devices based on the wellknown tungsten oxide as the coloring electrode, and Antimony Tin Oxide (ATO) as the ionstorage counter-electrode. We show that films deposited by Pulsed Laser Deposition (PLD) technique have an apparent Sb solubility up to 70 at %, and exhibit unusual electrochromic properties. Through potentiostatic tests we’ll demonstrate that depending on the composition which influences film morphology, the Sn-Sb-O films could either present a faradic or a capacitive-like behavior, associated to a color or a neutral switching over a wide range of potentials, respectively. The structural properties of ATO films are characterized by X-ray diffraction and transmission electron microscopy (TEM). Electrochromic behavior is studied by means of cyclic voltamperometry coupled with ex situ optical transmittance measurements in the visible range. The maximum proton-storage capacity is observed for ATO films containing 4050 at % Sb, while being quasi-neutral when switching over a wide range of potentials. These compositions are finally retained for the assembly of our WO3/proton-electrolyte/ATO devices, whose performances are reported. INTRODUCTION In recent years, owing to their capability of persistent and reversible color changes under a reversible electrochemical process, electrochromic materials have been widely involved in optical technology, particularly in the field of display panels, antiglare car rear-view mirrors and transmission modulation through building windows [1,2]. To ensure a large-scale development for this energy conscious architecture, the cost of smart windows needs to be lowered, especially for proton-working devices, which are easier to build than lithium conducting ones. Until now, the most durable all-solid inorganic system is composed of tungsten oxide as the cathodically colored working electrode and iridium [3] as the complementary counter-electrode, both components exchanging proton ions. However, owing to the high cost of iridium oxide, research has turned on cheaper electrochromic materials such as hydrous nickel oxide [4]. But the latter also presents non-negligible drawbacks such as a poor stability in acidic electrolytes. Thus, a need for alternative and economical materials, which can be used in the composition of protonconducting electrochromic devices, remained in order to constitute an ion-storage for WO3, and keep the same optical density over cycling. Based on our previous works we will show that the Sn-Sb-O system may effectively satisfy that need [5]. EXPERIMENTAL DETAILS Thin oxide films were prepared by pulsed laser deposition using a KrF excimer laser H8.3.1
beam (Lambda Physic, Compex 102, λ=248 nm) with a laser fluence of 1-2 J/cm2. The t
Data Loading...
