Viologen-Based Electrochromic Materials: From Small Molecules, Polymers and Composites to Their Applications

Abstract

Organic materials have gained considerable attention for electrochromic (EC) applications owing to improved EC performance and good processability. As a class of well-recognized organic EC materials, viologens have received persistent attention due to the structural versatility and property tunability, and are major active EC components for most of the marketed EC devices. Over the past two decades, extensive efforts have been made to design and synthesize different types of viologen-based materials with enhanced EC properties. This review summarizes chemical structures, preparation and EC properties of various latest viologen-based electrochromes, including small viologen derivatives, main-chain viologen-based polymers, conjugated polymers with viologen side-chains and viologen-based organic/inorganic composites. The performance enhancement mechanisms are concisely discussed. The current marketed viologens-based electrochromic devices (ECDs) are briefly introduced and an outlook on the challenges and future exploration directions for viologen-based materials and their ECDs are also proposed.

Targeted Synthesis of NIR Luminescent Rhenium Diimine cis,trans‐[Re()(CO)2(L)2]n+ Complexes Containing N‐Donor Axial Ligands: Photophysical, Electrochemical, and Theoretical Studies

“…Complex 2Re(BiPy-Me) 2 containing viologen-type N-methyl-4,4'-bipyridinium ligand (MQ + ) demonstrates rich electrochemistry both in oxidation and reduction modes (Figure 8) due to availability of low lying filled and empty orbitals of the aromatic ligands and a variety of charge transfer processes, which may occur in these systems. [65][66][67][68][69][70][71][72][73][74] Application of several spectro-electrochemical techniques in the study of the [Re(N N)(CO) 3 MQ] 2 + complexes [67][68][69][70]75,76] showed that CV of this type of compounds commonly display four reversible one-electron reduction waves related to successive one and two electron reduction of the diimine and MQ…”

Electrosynthesis and Electrochromism of a New Crosslinked Polydithienylpyrrole with Diphenylpyrenylamine Subunits

“…Thiophene, pyrrole, carbazole, viologen, triphenylamine and others are commonly used as building blocks in order to modify the electrochromic properties of the π-conjugated polymers [27][28][29][30][31][32]. Since 1986, poly(2,5-dithienylpyrrole)s (PSNS) have attracted particular interest, which could be easily synthesized via chemical and electrochemical polymerization of 2,5-dithienylpyrrole (SNS) unit [33][34][35].…”

Mono- and Di-Quaternized 4,4′-Bipyridine Derivatives as Key Building Blocks for Medium- and Environment-Responsive Compounds and Materials

“…There is a constant increase of published research works involving viologens (see Figure 1) and this perhaps is associated with the need for new materials corresponding to a variety of hi-tech applications. The importance of viologens is reflected through the numerous review papers (many of them very recent) underlining the high versatility of this class of compounds [9,10,[12][13][14][15]. Perhaps, the most reviewed subject regarding the viologens is their electrochromism [13,14,16].…”

“…Two important classes of 4,4 -bipyridine-based products with solvatochromic and/or environment-responsive character are reviewed: viologens (i.e., N,N -disubstituted derivatives) and monoquats (i.e., monosubstituted 4,4 -bipyridine derivatives). The multifunctional nature of these derivatives is analyzed and structure-property relations are discussed in connection to the role of these derivatives in various novel applications.Molecules 2020, 25, 1 2 of 30 recent) underlining the high versatility of this class of compounds [9,10,[12][13][14][15]. Perhaps, the most reviewed subject regarding the viologens is their electrochromism [13,14,16].…”

“…Molecules 2020, 25, 1 2 of 30 recent) underlining the high versatility of this class of compounds [9,10,[12][13][14][15]. Perhaps, the most reviewed subject regarding the viologens is their electrochromism [13,14,16].…”