Electrochromic organic materials applications

An important area where technology and heterocyclic chemistry combine is that of electroactive organic materials. The applications of these materials, which extend beyond simple replacements for metals, include use as conductors, superconductors, semiconductors, batteries, transistors, sensors, light emitting diodes (LEDs), and related electrochromic applications. This area is of great commercial importance. 

With regard to the importance for reversible lithium batteries and looking at the possible applications of reversible cathode materials in electrochromic (Sect. XI) and photo-electrochemical (Sect. XII) cells some significant results of this rapidly growing field should be presented. Both inorganic and organic materials are inv -gated. 

K-Conjugated polymers and oligomers are organic materials with many interesting and useful properties [1, 2], Examples of this class of materials include polyacetylene, polythiophene, polypyrrole, poly(phenylenevinylene) and their derivatives. Electronic conductivity, luminescence and nonlinear optical behavior are all observed in these materials and these properties have been exploited in applications such as electroluminescent devices (polymer light-emitting devices or PLEDs), electrostatic coatings, electrochromic windows, chemical sensors and memory devices [3-9]. 

Mortimer RJ, Dyer AL, Reynolds JR. Electrochromic organic and polymeric materials for display applications. Displays 2006 27(1) 2—18. 

Organic thin films have been extensively investigated in connection with the attempts to apply organic materials to electronic and electrochemical devices. Phthalocyanine and its metallo-derivatives are particularly of interest in this field a wide variety of physical and physicochemical properties applicable to such devices, i.e., photo-conductivity, photovoltaic effect a, electrochromism, electrocatalysis , have been reported for their films. 

At present, intercalation compounds are used widely in various electrochemical devices (batteries, fuel cells, electrochromic devices, etc.). At the same time, many fundamental problems in this field do not yet have an explanation (e.g., the influence of ion solvation, the influence of defects in the host structure and/or in the host stoichiometry on the kinetic and thermodynamic properties of intercalation compounds). Optimization of the host stoichiometry of high-voltage intercalation compounds into oxide host materials is of prime importance for their practical application. Intercalation processes into organic polymer host materials are discussed in Chapter 26. 

Stabilization of the redox cycle is relatively important in construction of potentially useful electrochromic materials, because the molecules needed for application require high redox-stability. Recently, S. Hiinig et al. proposed the concept of violene-cyanine hybrid to produce stabilized organic electrochromic materials (3). The hybrid is constructed by a violene-type redox system containing delocalized closed-shell polymethine dyes as end groups. The hybrid is expected to exhibit the color of a cyanine dye, by an overall two-electron... 

A further electro-optical effect which is studied for applications in display is electrochromism. Electrochromism is characterized as a reversible colour change induced in some organic and inorganic materials by an applied electric field or current. According to Chang [263], the physical mechanisms responsible for these phenomena are electronic and electrochemical in nature. A schematic electrochromic reaction can be formulated as follows ... 

Functionalized PTs have been investigated in various applications, e.g., their ability to detect, transduce, and amplify various physical or chemical informations into an electrical or an optical signal has led to the development of devices capable of detecting analytes or biomolecules in the field of environment, security, and biotechnology. Currently, functionalized PTs play a key role as active materials in the development of electrochromic devices and electronic devices, such as OLEDs, OFETs, and organic solar cells. 

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