Conductive polymers electrochromic display

Conducting polymers have found applications in a wide variety of areas,44 45 and many more have been proposed. From an electrochemical perspective, the most important applications46 appear to be in batteries and supercapacitors 47,48 electroanalysis and sensors49-51 electrocatalysis,12,1, 52 display and electrochromic devices,46 and electromechanical actuators.53... 

The enormous efforts put into the basic research and development of conducting polymers are naturally related to hopes of feasible technical apphcations The starting point of this development was the discovery that PA can fimction as an active electrode in a rechargeable polymer battery. Since then, the prospects of technical application have grown considerably Apart from the battery electrode, conducting polymers are discussed as potential electrochromic displays... 

The development of conducting polymers is naturally related to hopes of feasible technical applications. Thus, conducting polymers are discussed as active battery electrodes [10], electrochromic displays (BCD) [11], anticorrosives [12], sensors [13], electrocatalysts [14], antistatic materials [15], or light-emitting materials (OLED) [16],... 

Since the band structure which develops upon doping induces changes not only in the conductivity but also in the optical absorption (see Fig. 9.8), conducting polymers may be exploited for electrochromic displays, which are optical devices with marked colour transitions. An example is illustrated diagramatically in Fig. 9.18. 

Poly(3,4-ethylenedioxythiophene) (PEDOT) is a particularly popular conducting polymer as it can have good conductivity and stability and has a low band gap, which is pertinent to its use in photovoltaic devices. A number of authors have now studied the electrochemical synthesis of this polymer in different ionic liquids. Lu et al. [77] first demonstrated the use of [C4mim][BF4] to electrodeposit PEDOT onto ITO, and its application in an electrochromic numeric display. 

High-resolution circuitry and active devices employing Langmuir-Blodgett film techniques or polymer-based transistors are being considered for the sophisticated electronics required in future vehicles. Temperature or energy balance in the vehicle could be controlled through conductive polymers or semiconductor deposits on electrochromic windows. Electroluminescent liquid crystals and fluorescent and electrochromic materials used for visual displays show promise for future development. 

Conducting polymers such as polyacetylene, polypyrrole, polyaniline, polythiophene, etc. have been actively studied for use in various fields due to their interesting properties batteries,46 electrochromic displays,47 materials for supercapacitors,48 corrosion protection,49 protecting layers for static electricity,50 materials for organic electroluminescence displays,51 sensing materials,52 etc. Polypyrrole is reported to be extremely rigid, with a semi-crystalline structure. 

As an environmentally stable conducting polymer, polyaniline has been recognized as a potential candidate for application in secondary battery electrodes, sensors, electrochromic display devices, microelectronics, ion-exchange resins etc. [151-161]. 

An electrochromic display (BCD) is a thin solid state device that changes color reversibly when subjected to a small electrical potential. Since the doping processes of certain conducting polymers are accompanied by changes in the color, this effect has been conveniently exploited in the realization of BCD devices. Thin films of a conducting polymer polythiophene, for example, are red in the doped state and deep blue in the undoped state. 

Many electrochemically dopant-induced structure-property changes in conducting polymers have been described for use in, for example, electrochromic windows and displays, electrochemically controlled chemical separation and delivery systems, redox capacitors, electromechanical actuators, etc.,32. Some of these are apparently close to commercial application. Polypyrrole capacitors are already in conunercial production,27. 

Flexible electrochromic devices (ECDs) are becoming increasing important for their promising applications in many areas, such as the portable and wearable electronic devices, including smart windows, functional supercapacitors, and flexible displays. Typically, an ECD consists of four parts of substrate, conductive electrode, electrochromic material, and electrolyte. Enormous efforts have been made to improve the flexibility of ECDs including utilizing flexible polymer substrates and conductive materials. 

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