Electrochromism

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

Electrochemistry and electrochromic behavior of Langmuir-Blodgett films of octakis-substituted rare-earth metal diphthalocyanines

Abstract: Heavy rare-earth metal diphthalocyanine complexes with alkoxy or alkyl substituents dissolved in common organic solvents formed stable Langmuir-Blodgett (L-B) films. The cyclic voltammogram of L-B films on indium-tin oxide Nesa glass electrodes showed smaller peak splitting and more symmetrical shape than those of corresponding solvent-cast films. The multicolor electrochromism was found both in L-B film and cast film systems in contact with an aqueous HCl-KCl electrolyte. For the completion of the color change, different potentials should be applied with different substituents. More than 1 V (versus SCE) was necessary for the tert-butyl-substituted complexes and less than 0.8 V for the propoxy-substituted ones. After about 7 h of repetitive cycling at 100 mV/s between 0 and 0.6 {approximately} 0.9 V, the relative Q-band intensity decreased by 2-5%, demonstrating good electrochemical stability.

Electrochromic Behavior of Nickel Oxide Electrodes II . Identification of the Bleached State by Raman Spectroscopy and Nuclear Reactions

Abstract: Three different types of nickel oxide electrochromic films are colored and bleached in 1M KOH solution: porous NiO prepared by anodic oxidation of nickel, NiO(OH) x obtained by reactive evaporation, and Ni(OH) 2 cathodically deposited. Their crystallographic and chemical identification in the colored and bleached states after one cycle and after long time performance testing is obtained by Raman spectroscopy. Nuclear reaction analysis is also performed

Colorless-to-colorful switching electrochromic polyimides with very high contrast ratio

Abstract: Colorless-to-colorful switching electrochromic polymers with very high contrast ratio are unattainable and attractive for the applications of smart wearable electronics. Here we report a facile strategy in developing colorless-to-colorful switching electrochromic polyimides by incorporating with alicyclic nonlinear, twisted structures and adjusted conjugated electrochromophores, which minimize the charge transfer complex formation. It is noted that, by controlling the conjugation length of electrochromophore, the colorless-to-black switching electrochromic polymer film (PI-1a) exhibites an ultrahigh integrated contrast ratio up to 91.4% from 380 to 780 nm, especially up to 96.8% at 798 nm. In addition, PI-1a film with asymmetric structure also demonstrates fast electrochemical and electrochromic behaviors (a switching and bleaching time of 1.3 s and 1.1 s, respectively) due to the loose chain stacking, which provides more pathways for the penetration of counterion. Moreover, the colorless-to-black EC device based on PI-1a reveals an overall integrated contrast ratio up to 80%. Electrochromic polymers (ECPs) receive great attention due to their facile colour tunablility, however colourless-to-black ECPs with high contrast ratio are still unattainable. Here the authors develop high contrast colourless-to-black switching polyimides by following specific molecular design criteria.

Enhanced Electrical Switching and Electrochromic Properties of Poly(p-phenylenebenzobisthiazole) Thin Films Embedded with Nano-WO3

Abstract: The electrical switching and electrochromic phenomena of a novel nanocomposite comprising poly(p-phenylenebenzobisthiazole) (PBZT) and tungsten oxide (WO 3 ) nanoparticles are investigated as a function of the nanoparticle loading. Both dissolving PBZT and doping PBZT backbone structure with acid are achieved by one simple step. Chlorosulfonic acid (CSA) is used as a solvent and spontaneously transformed to sulfuric acid upon exposure to moisture. The formed sulfuric acid serves as doping agent to improve the electrical conductivity of PBZT. The most significant enhancement of electrical switching is observed in the nanocomposites with low weight fraction (5%). The electrical conductivity of 5% WO 3 /PBZT nanocomposite thin film is increased by about 200 times and 2 times, respectively, as compared to those of the as-received PBZT and PBZT/CSA thin films. As the nanoparticle loading increases to 20% and 30%, the nanocomposites follow an ohmic conduction mechanism. Stable electrical conductivity switching is observed before and after applying a bias on the pristine PBZT and WO 3 /PBZT nanocomposite thin films. Electrochromic phenomena of both PBZT and WO 3 / PBZT nanocomposite thin films with high contrast ratio are observed after applying a bias (3 V). The mechanisms of the nanoparticles in enhancing the electrical switching and electrochromic properties are proposed.

Preparation and electrochromic properties of rf‐sputtered molybdenum oxide films

Abstract: Properties of rf‐sputtered molybdenum oxide films for electrochromic display devices have been investigated. This report mainly concerns the dependence of the properties on the oxygen concentration in the sputtering atmosphere. The oxide films were prepared by rf sputtering from a compressed powder MoO3 target under an operating pressure of 4×10−2 Torr using a mixture of Ar‐0.5–50% O2. Electrical resistivity of the films formed increases with increasing oxygen concentration in the sputtering atmosphere and ranges from 2.5×1010 to ∼1×1012 Ω cm. Spectral transmittance of the films is about 85% in the visible and near‐infrared region. Optical band gap and refractive index of these films are 2.67–2.76 eV and 2.01–2.26, respectively. Electrochemichromic properties of the films were also studied using asymmetric cells, and it was found that a good electrochromic performance was obtained usually by the cells composed of the films with a resistivity of 2.5×1010 Ω cm.