Electrochromism

About: Electrochromism is a research topic. Over the lifetime, 13097 publications have been published within this topic receiving 294637 citations.

An Electrochromic Window Based on Li x WO 3 / ( PEO ) 8LiClO4 / NiO

Abstract: Electrochromic materials are characterized by reversible but persistent changes of the optical properties when subjected to suitable electrochemical reactions. Electrochromism can be utilized in windows, most conveniently by exploiting all-solid-state multilayer coating backed by glass. The multilayer coating should comprise the following sequence of layers: a transparent and electrically conducting base layer, an electrochromic layer, and electrolyte, a conterelectrode, and a transparent conducting top layer. For window applications, the electrolyte should be transparent, and the conterelectrode must be either optically passive (colorless irrespective of its ionic content) or electrochromic in a sense that is complementary to the electrochromism of the electrochromic layer. The latter condition implies that if the electrochromic layer is cathodic (anodic), the counterelectrode must be anodic (cathodic). This paper reports preliminary data taken on samples with electrochromic layers based on tungsten oxide, WO{sub 3}, and nickel oxide, NiO, and an intermediate solid electrolyte of poly(ethylene oxide) doped with lithium perchlorate, (PEO){sub 8}LiClO{sub 4}, where 8 signifies the number of oxygen heteroatoms per lithium ion.

In situ crystallization of high performing WO3-based electrochromic materials and the importance for durability and switching kinetics

Abstract: A chemical self-assembled synthesis was used to prepare disordered porous semicrystalline WO3-based cathodic electrochromic films. The resulting films were characterized with transmission electron microscopy (TEM), scanning electron microscopy (SEM), X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), N2 physisorption, Fourier transform infrared spectroscopy (FTIR) and near-edge X-ray absorption fine structure (NEXAFS). The electrochromic performance was evaluated in a Li-ion electrolyte (i.e., 1 M LiClO4 dissolved in propylene carbonate) with cyclic voltammetry (CV), galvanostatic cycling with potential limitation (GCPL) and chronoamperometry (CA) techniques. It is demonstrated that the crystallinity of WO3 thin films can be readily tuned with the variation of annealing temperatures and TiO2 addition. The results demonstrated excellent stability and durability (i.e., 1500 GCPL cycles in 32 days) for WO3 electrode annealed at 350 °C, ultrafast switching kinetics for WO3–TiO2 electrode (i.e., bleaching and coloration times are 5.5 s and 4.2 s, respectively) and excellent charge reversibility (%R ≈ 100%). Electrochemical, TEM and Raman spectroscopy studies suggest that a change in degree of crystallinity in WO3 occurs during the extended durability test, which then influences the durability and switching kinetics.

An electrochromic ionic liquid: design, characterization, and performance in a solid-state platform.

Abstract: This work describes the synthesis and characteristics of a novel electrochromic ionic liquid (IL) based on a phosphonium core tethered to a viologen moiety. When integrated into a solid-state electrochromic platform, the viologen modified IL behaved as both the electrolyte and the electrochromic material. Platform fabrication was achieved through in situ photo-polymerization and encapsulation of this novel IL within a hybrid sol–gel. Important parameters of the platform performance, including its coloration efficiency, switching kinetics, and optical properties were characterised using UV–vis spectroscopy and cyclic voltammetry in tandem. The electrochromic platform exhibits a coloration efficiency of 10.72 cm2 C–1 and a varied optical output as a function of the incident current. Despite the rather viscous nature of the material, the platform exhibited approximately 2 orders of magnitude faster switching kinetics (221 s to reach 95 % absorbance) when compared to previously reported electrochromic ILs (18...

Electrochromic properties of intercrossing nickel oxide nanoflakes synthesized by electrochemically anodic deposition

Abstract: Nanostructured nickel oxide film is synthesized directly onto a transparent and conducting indium tin oxide coated glass substrate by electrochemically anodic deposition from an aqueous solution. The deposited nickel oxide film has an intercrossing nanoflake and highly porous morphology. X-ray diffraction peaks of the film resemble closely to the cubic NiO structure. The deposited film oxidized/reduced electrochemically at 0.36 and 0.25V versus a saturated Ag∕AgCl electrode, respectively, which corresponds to the reversible changes in coloration and bleaching. The difference in optical response (transmittance) ΔT at wavelength of 550nm between the colored state and bleached state can reach as high as 80%.

Obtaining of films of tungsten trioxide (WO3) by resistive heating of a tungsten filament

Abstract: Resumen en: Thin film of tungsten oxide (WO3) has been studied extensively as an electrochromic material and has numerous applications in electrochromic devices, sma...