No abstract

Pyrene is composed of four benzene rings and has a unique planar melting ring structure.

Two donor units (D)‐acceptor units (A) type monomers were synthesized by Stille coupling reaction, and then three D‐A type hybrid polymers based on 3,4‐ethylenedioxythiophene and various benzodiazoles were synthesized by electrochemical polymerization. Spectroelectrochemical and kinetic studies of these polymers showed that all polymer films exhibited excellent electrochromic behavior, obvious optical contrast, and excellent stability. Among them, the response time of P3 film was the shortest (tc = 1.6 s, tb = 2.2 s), the coloring efficiency of P2 film was the highest (CE = 333 cm2·C−1), and the stability of P1 was the best (the ΔT loss of P1 after 1000 s cycles is only 2.3%). Therefore, these data prove that these new polymers have great potential in applications as electrochromic materials.

Based on the performance of improving the stabilities and coloring efficiencies of triphenylamine polymers, this paper separately synthesized different diamines and 3,4-dimethylthieno[2,3-b]thiophene-2,5-dicarboxylic acid, and the electrochromic functions of the polymer films were studied on indium-tin oxide glass (ITO) glass. The polymers had a thiophene group, which was rich in π-electrons and conducive to molecular stability, and showed good stabilities. Ultraviolet spectrum showed that all the six polymers had a wide absorption band in the neutral range of 200-700 nm. Electrochromic analysis showed that the six kinds of polymer films all showed reasonable optical contrast, short response time and low band gap in the infrared spectrum range of 200-1000 nm. Among them, the film formed by PAD2 on ITO glass had better electrochromic properties, longer bleaching response time (t c = 1.3 s, t b = 4.1 s), PAD3 had better coloration efficiency (214 cm 2 C À1 ).

The development prospect of conductive electrochromic (EC) polymers requires the design of polymers with high performance and good stability. Here, a new scheme is designed to enhance EC properties by adjusting the monomer molecular structure. Four monomers with different structures based on thiophene and 3,4-ethylenedioxythiophene (EDOT) are designed and synthesized. The corresponding polymer films (P1, P2, P3, and P4) are prepared by electrochemical polymerization at low applied potential. The spatial structure-performance relationship of precursors with different structures and polymers is systematically discussed. In the electropolymerization experiments, it is noted that P3 has no EC property. This may be connected to the spatial structure of P3 polymerization which is not suitable for charge transporting. By contrast, the other three polymers exhibit excellent electrochemical properties. The diffusion rate higher of P1 has also been corroborated by using electrochemical impedance spectroscopy (EIS) spectrum. The P1 film has the best stability and fastest colorized time among the samples; such superior electrochemical property may be associated with the closely stacked formed by the unique sheet-like spatial structure. The design of the space structure has a significant impact on the optical and electrical properties of the polymer film.