Electrochromism

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

Soluble Narrow Band Gap and Blue Propylenedioxythiophene-Cyanovinylene Polymers as Multifunctional Materials for Photovoltaic and Electrochromic Applications

Abstract: A family of soluble narrow band gap donor-acceptor conjugated polymers based on dioxythiophenes and cyanovinylenes is reported. The polymers were synthesized using Knoevenagel polycondensation or Yamamoto coupling polymerizations to yield polymers with molecular weights on the order of 10 000-20 000 g/mol, which possess solubility in common organic solvents. Thin film optical measurements revealed narrow band gaps of 1.5-1.8 eV, which gives the polymers a strong overlap of the solar spectrum. The energetic positions of the band edges were determined by cyclic voltammetry and differential pulse voltammetry and demonstrate that the polymers are both air stable and show a strong propensity for photoinduced charge transfer to fullerene acceptors. Such measurements also suggest that the polymers can be both p- and n-type doped, which is supported by spectroelectrochemical results. These polymers have been investigated as electron donors in photovoltaic devices in combination with PCBM ([6,6]-phenyl C(61)-butyric acid methyl ester) as an electron acceptor based on the near ideal band structures designed into the polymers. Efficiencies as high as 0.2% (AM1.5) with short circuit current densities as high as 1.2-1.3 mA/cm(2) have been observed in polymer/PCBM (1:4 by weight) devices and external quantum efficiencies of more than 10% have been observed at wavelengths longer than 600 nm. The electrochromic properties of the narrow band gap polymers are also of interest as the polymers show three accessible color states changing from an absorptive blue or purple in the neutral state to a transmissive sky-blue or gray in the oxidized and reduced forms. The wide electrochemical range of electrochromic activity coupled with the strong observed changes in transmissivity between oxidation states makes these materials potentially interesting for application to electrochromic displays.

Stretchable and Wearable Electrochromic Devices

Abstract: Stretchable and wearable WO3 electrochromic devices on silver nanowire (AgNW) elastic conductors are reported. The stretchable devices are mechanically robust and can be stretched, twisted, folded, and crumpled without performance failure. Fast coloration (1 s) and bleaching (4 s) time and good cyclic stability (81% retention after 100 cycles) were achieved at relaxed state. Proper functioning at stretched state (50% strain) was also demonstrated. The electrochromic devices were successfully implanted onto textile substrates for potential wearable applications. As most existing electrochromic devices are based on rigid technologies, the innovative devices in their soft form hold the promise for next-generation electronics such as stretchable, wearable, and implantable display applications.

Nanocrystalline TiO2 (Anatase) Electrodes: Surface Morphology, Adsorption, and Electrochemical Properties

Abstract: Films of sintered anatase nanoparticles are promising electrode materials for solar cells, electrochromics, and lithium batteries. For the last application, the anatase phase is essential, since the Li{sup +} insertion into other TiO{sub 2} polymorphs (rutile, brookite) is mostly considered to be negligible. Ten different nanotextured TiO{sub 2} films were prepared from six commercial and four laboratory synthesized precursors. Krypton adsorption isotherms on the films and apparent powders indicate the effect of sintering and agglomeration. Electrochemical characterization of the films was aimed at double-layer charging and Li{sup +} insertion. The relations between the film`s morphology, adsorption properties, and electrochemical behavior in the accumulation regime are discussed.