Electrochromism

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

Highly stable anodic green electrochromic aromatic polyamides: synthesis and electrochromic properties

Abstract: A 4-methoxy-substituted triphenylamine containing the aromatic diamine, 4,4′-diamino-4″-methoxytriphenylamine (2), was synthesized by the caesium fluoride-mediated condensation of p-anisidine with 4-fluoronitrobenzene, followed by palladium-catalyzed hydrazine reduction of the dinitro intermediate. A series of new polyamides with pendent 4-methoxy-substituted triphenylamine (TPA) units having inherent viscosities of 0.27–1.39 dL g−1 were prepared via the direct phosphorylation polycondensation of various dicarboxylic acids and the diamine (2). All the polymers were readily soluble in many organic solvents, such as N-methyl-2-pyrrolidinone (NMP) and N,N-dimethylacetamide (DMAc), and could be solution-cast into tough and flexible polymer films. These aromatic polyamides had useful levels of thermal stability associated with their relatively high softening temperature (242–282 °C), 10% weight-loss temperatures in excess of 470 °C, and char yields at 800 °C in nitrogen higher than 60%. The hole-transporting and electrochromic properties are examined by electrochemical and spectroelectrochemical methods. Cyclic voltammograms of the polyamide films cast onto an indium-tin oxide (ITO)-coated glass substrate exhibited reversible oxidation at 0.73–0.79 V versus Ag/AgCl in acetonitrile solution, and revealed excellent stability of electrochromic characteristics with a color change from colorless to green at applied potentials ranging from 0.00 to 1.05 V. These anodically polymeric electrochromic materials not only showed excellent reversible electrochromic stability with good green coloration efficiency (CE = 374 cm2 C−1) but also exhibited high contrast of optical transmittance change (ΔT %) up to 85% at 787 nm and 30% at 391 nm. After over 1000 cyclic switches, the polymer films still exhibited excellent stability of electrochromic characteristics.

Poly(3,4-alkylenedioxypyrrole)s: Highly Stable Electronically Conducting and Electrochromic Polymers

Abstract: A series of poly(3,4-alkylenedioxypyrrole)s are reported as a new class of electronically conducting polymers exhibiting especially low oxidation potentials from ca. −0.6 to −0.4 V vs Fc/Fc+ (equivalent to −0.15 to +0.05 V vs SCE) as desired for ambient stability of the doped and conducting states. These polymers exhibit unique combinations of multicolor electrochromism, switching from a red or orange neutral state to a light blue/gray doped state, passing through a darker intermediate state (brown), as examined by in situ colorimetry. High spectral contrast ratios have been measured throughout the visible region with a maximum Δ%T = 76% at 534 nm for poly[3,4-(2,2-dimethylpropylenedioxy)pyrrole) (PProDOP−(CH3)2). PProDOP−(CH3)2 exhibits outstanding redox switching stability, being able to undergo 40 000 deep double-potential switches between its doped and neutral states (1 s, Δ%Tmax = 76%) while retaining more than 90% of its electroactivity. A high level of stability to overoxidation has also been obser...

Stabilization of superionic α -Agl at room temperature in a glass matrix

Abstract: SINCE the discovery1 that the high-temperature phase of silver iodide (α-AgI) has an ionic conductivity comparable to that of the best liquid electrolytes, solid electrolytes have attracted wide interest. Possible applications of these materials range from solid-state batteries to electrochromic displays and sensors2. Although α-AgI displays conductivities of more than 10 S cm−1 (ref. 3), owing to the almost liquid-like mobility of Ag+ ions, the crystal transforms below 147 °C to the β-phase with a conductivity of only ∼10−5 S cm−1 at room temperature. Efforts to achieve good conductivities at lower temperatures have focused on the addition of a second component to AgI to form solid solutions or new compounds such as RbAg4I5 and Ag2HgI4 (refs 4–7). Here we report our success in depressing the α→β transformation temperature so as to stabilize α-AgI itself at room temperature. We use a melt-quenching technique to prepare crystallites of α-AgI frozen into a silver borate glass matrix. The quenched material showed diffraction peaks characteristic of α-AgI and displayed ionic conductivities of about 10−1S cm−1. Further development of these glass/crystal composites may make the high ionic conductivity of α-AgI available for room-temperature solid-state applications.