High Contrast Ratio and Rapid Switching Electrochromic Polymeric Films Based on 4-(Dimethylamino)triphenylamine-Functionalized Aromatic Polyamides

Abstract

A series of electroactive aromatic polyamides with 4-(dimethylamino)triphenylamine [(NMe 2 )TPA] units in the backbone were prepared from a newly synthesized diamine monomer, 4,4′-diamino-4′′-(dimethylamino)triphenylamine, and various aromatic dicarboxylic acids via the phophorylation polyamidation reaction. These polyamides are readily soluble in many organic solvents and can be solution-cast into tough and amorphous films. They had useful levels of thermal stability associated with relatively high glass-transition temperatures (277-298 °C), 10% weight loss temperatures in excess of 500 °C, and char yields at 800 °C in nitrogen higher than 67%. The polymer films showed reversible electrochemical oxidation accompanied by strong color changes with high coloration efficiency, high contrast ratio, and rapid switching time. The optical transmittance change (∆%T) at 640 nm between the neutral state and the fully oxidized state is up to 88%, and the coloration efficiency is as high as ca. 261 cm 2 /C with high optical density change (δOD) up to 0.94. The polymers also displayed low ionization potentials as a result of their (NMe 2 )TPA moieties. Cyclic voltammograms of the polyamide films on the indium-tin oxide (ITO)-coated glass substrate exhibited a pair of reversible oxidation waves with very low onset potential of 0.35 V (vs Ag/AgCl) in acetonitrile solution.

Interfacial redox centers as origin of color switching in organic electrochromic device

“…A 50 % transparency in the second cycle onwards has been considered as OFF state whereas ON state corresponds to 100 % transparency. Additionally, contrast between the ON and OFF states can be calculated by defining colour contrast ratio (CCR) using the following equation [35][36][37].…”

Synthesis and Photosensitive Properties of Poly(aryl imino) Containing Azobenzene Group (PAI‐A)

“…Upon complete protonation, the color of the polymer solution was transferred from yellow to blue which differs significantly from other polymers containing azobenzene group where the color transferred from yellow to purple. 12,13 The blue color is due to the interaction of the positive charge with the extent of the π-electron system in the former. …”

“…10,11 Owing to the photoactivities, a large number of polymers containing azobenzene groups have attracted interest because of their potential uses in various photonic applications. 12,13 Thus, the Pd-catalyzed polycondensation of 4,4'-dibromobenzophenone with 4,4'-diaminoazobenzene to afford polymers (PAI-A) were carried out. These polymers have an azobenzene structure in the main chain and are expected to show photochromic properties similar to those of the reported polymers containing azobenzene groups.…”

Synthesis, characterization and electrochromic properties of polyamides having triphenylamine derivatives

“…Among the electrochromic materials, oxidizable organic polymers containing triphenylamine derivatives have attracted considerable interest because triphenylamine derivatives can be oxidized easily in the nitrogen center to form a stable cationic radical, and the oxidation process is always associated with a noticeable change in coloration [11,12]. Moreover, the electrochemical properties, such as the band gap, color change and response time of triphenylamine derivatives, can be controlled by adjusting the incorporated substituent's position and introducing side groups.…”