Toward Purple-to-Green-to-Transmissive-to-Black Color Switching in Polymeric Electrochrome

Abstract

A novel 3,4-ethylenedioxythiophene (EDOT)-based donor−acceptor electroactive monomer (HCQE) bearing carbazole subunit is synthesized, and then the corresponding polymer, poly(HCQE), is directly deposited onto ITO/glass surface via electrochemical process. Spectroelectrochemical studies demonstrate that poly(HCQE) is capable of showing both n-and p-doping processes. Hence, this low band polymer serves the multielectrochromic feature at three separate states (−0.4 to −2.0 V, −0.4 to 1.2 V, and 1.2 to 2.0 V) with a highly unique near colorless and colored states, fast switching times, redox switching stability, and exceptional transmittance change. To the best of our knowledge, this is the first report of a neutral state green multielectrochromic polymer exhibiting successive switching of colored-to-bleached-to-colored in three distinct regimes.

Synthesis and characterization of novel donor–acceptor type neutral green electrochromic polymers containing an indolo[3,2-b]carbazole donor and diketopyrrolopyrrole acceptor

“…Besides, for the sake of transparent color in the oxidized state, the two bands should be controlled by the same potentials and disappear simultaneously. [16][17][18][19] Up to now, there are several strategies to adjust the polymer color such as growing conjugate chain, tuning steric interaction and adopting donor-acceptor (D-A) approach, among which synthesizing D-A type polymers is by far the most popular and effective method through designing different donors and acceptors. 16,20 Furthermore, another signicant advantage of D-A structure is the lower band gap of polymer owing to the inter-or intra-molecular charge transfer effects from push/pull interactions between donor and acceptor.…”

“…Various neutral green D-A type polymers previously reported primarily employ thiophene derivatives, especially 3,4-ethoxylenedioxythiophene (EDOT) and 3,4-propylenedioxythiophene (ProDOT) as the donors, which causes the diversity of polymer species depends on changes in acceptors. [16][17][18][19]25,29 So actively exploring new kind of donors can be considered as an effectual way to expand green electrochromic polymers. Indolo [3,2-b] carbazole (IC), as an important class of donor unit containing electron-rich indole and carbazole groups, has notable planar and rigid conjugate structures similar with pentacene, which could facilitate charge carrier effectively and result in high hole transporting ability for its corresponding polymers.…”

Synthesis, Characterization and Application of Four Novel Electrochromic Materials Employing Nitrotriphenylamine Unit as the Acceptor and Different Thiophene Derivatives as the Donor

“…However, the preparation of such polymers is very complicated, only high purity monomer can meet to this purpose, and it needs tedious workup to obtain the monomers with high purity [ 20 ]. In addition, the response times of such polymers in electrochromic switching are usually longer than other CPs, e.g., polythiophenes, which is an obvious disadvantage for high quality electrochromic materials [ 20 , 21 ].…”

Effects of Fluoro Substitution on the Electrochromic Performance of Alternating Benzotriazole and Benzothiadiazole-Based Donor–Acceptor Type Copolymers

“…When the interactions are sufficiently intense, the difference of energy levels between highest occupied molecular orbital (HOMO) and lowest unoccupied molecular orbital (LUMO) are reduced accordingly, which can lead to lower band gap and favorable electrochromic properties of the polymers [ 11 , 12 ]. For the sake of further fine-tuning solubility, stability, optical contrast, switching time and coloration efficiency of the electrochromic polymers, as well as color change of RGB (red, green, blue), various strategies of molecule structure design of D–A type polymer have been researched widely [ 13 , 14 ]. Recently, a new kind of donor–acceptor(1)–donor–acceptor(2) (D–A 1 –D–A 2 ) type polymer, containing two different alternately arranged acceptors in the polymer backbone, has attracted much attention.…”