Electrochromism

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

Composite Coloration Efficiency Measurements of Electrochromic Polymers Based on 3,4-Alkylenedioxythiophenes

Abstract: We report a method to measure the composite coloration efficiency of organic electrochromic polymers at 95% of the total optical density change measured at λmax. This practical method is useful for the comparison of organic polymers as well as inorganic electrochromic oxides and for gaining insights into the reasons for increased efficiencies in organic polymer systems. Three polymers from the family of the poly(3,4-alkylenedioxythiophenes) (PXDOTs) were chosen, due to their well-behaved electrochromic properties, to develop the tandem chronoabsorptometry/chronocoulometry method. Coloration efficiencies were measured by monitoring the amount of injected/ejected charge as a function of the change in optical density of the polymer film. The results of these experiments revealed a significant relationship between structure and coloration efficiency determined at λmax in organic polymers. Poly(3,3-dimethyl-3,4-dihydro-2H-thieno[3,4-b]dioxepine) (PProDOT-Me2) possessed the highest coloration efficiency (375 cm...

Roll-to-Roll Production of Transparent Silver-Nanofiber-Network Electrodes for Flexible Electrochromic Smart Windows.

Abstract: Electrochromic smart windows (ECSWs) are considered as the most promising alternative to traditional dimming devices. However, the electrode technology in ECSWs remains stagnant, wherein inflexible indium tin oxide and fluorine-doped tin oxide are the main materials being used. Although various complicated production methods, such as high-temperature calcination and sputtering, have been reported, the mass production of flexible and transparent electrodes remains challenging. Here, a nonheated roll-to-roll process is developed for the continuous production of flexible, extralarge, and transparent silver nanofiber (AgNF) network electrodes. The optical and mechanical properties, as well as the electrical conductivity of these products (i.e., 12 Ω sq-1 at 95% transmittance) are comparable with those AgNF networks produced via high-temperature sintering. Moreover, the as-prepared AgNF network is successfully assembled into an A4-sized ECSW with short switching time, good coloration efficiency, and flexibility.

Controlled synthesis of WO3 nanorods and their electrochromic properties in H2SO4 electrolyte

Abstract: Uniform crystalline WO3 nanorods were synthesized by a lithium- or sulfate-free hydrothermal process with NaCl as a capping agent. It is found that variations in the pH and amount of capping agent have critical influence on the morphologies of the resultant WO3 nanostructures. The electrochromic film comprised of the as-synthesized crystalline WO3 nanorods exhibits a fast coloration/bleaching switching, coloration efficiency comparable to that of conventional amorphous WO3 films, and a high H+ ion-insertion ability in 0.5 mol/L H2SO4 solution without degradation.

Multiple-Color Electrochromism from Layer-by-Layer-Assembled Polyaniline/Prussian Blue Nanocomposite Thin Films

Abstract: The creation of new materials systems for lightweight and flexible displays is an extremely active research field. Electrochromic displays possess a keen advantage over other technologies because it is possible for a single electrochromic pixel to produce multiple colors in addition to white, depending on applied potential. This possibility has proven quite challenging to achieve in practice. Here we present the successful fabrication of a multiply colored electrochromic electrode using layer-by-layer (LBL) assembly. The electrode films are created by exploiting intrinsic electrostatic attraction between the polycation poly(aniline) (PANI) and a negatively ionized Prussian Blue (PB) nanoparticle dispersion. The resultant organic/inorganic nanocomposites exhibit excellent smoothness and a classical linear increase in film thickness with assembly exposure steps. Electrochemical and spectrophotometric characterization confirms the distinct and noninteracting contributions from PANI and PB and reveals that bo...