Electro-optical applications

6 APPLICATIONS AND APPLICABLE MATERIALS 7.6.1 Electro-optical Applications 

While comb LCPs exhibit display-relevant properties, they do not seem appropriate for real-time active displays of the type associated with 

SMLC the viscosity of the polymer matrix imposes switching times that are too slow. Instead, use can be made of the combination of thermoplastic and thermotropic behaviour. Nakamura et have listed the merits of polymeric versus metallic components, and of polymeric versus SMLC components, in electro-optic devices. Compared to metals, polymers have low thermal conductivity, low toxicity, low manufacturing costs and good environmental stability. Compared to SMLC systems they offer possibilities of large size, free-standing, flat and thin displays, and may be compatible with directly deposited electrodes (avoiding cumbersome connection substrates). Even so, McArdle has pointed out that many practical problems remain before significant commercial exploitation becomes a reality. 

Various designs are possible to allow for choice of contrast (e.g. dark track on light background or vice versa), and devices can be fabricated from LCPs doped with dyes for coloured storage or for enhanced 

Ferroelectric behaviour in a material implies a macroscopic dipole. In most materials that contain polar molecules, the dipole moments associated with the macroscopic sum of constituent molecules are non-additive each molecule is dipolar but the molecules are so arranged in the material that the moments average to zero in the absence of an external polarizing influence. The key property of a ferroelectric 

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M. Okawata, T. Kitao, T. Hirashima, and M. Matsuoka, Organic Colorants A Handbook of Selected Dyesfor Electro-Optical Applications, Elsevier, Amsterdam and New York, 1988. 

Since the end of the 1970s, the polyimides have been introduced for the production of electronic components mainly for the passivation. But more and more they are interesting for the integrated circuits and multichip modulus fabrications. Processability and dielectric and thermomechanical properties are the most attractive features of these materials for the electronic31 and electro-optical applications.32... 

Electron microscopy, 163-164 Electro-optic applications, polyimide, 269 Electrophilic aromatic substitution, 329-334, 398... 

Characterization of Liquid Crystalline Polymers for Electro-optic Applications... 

Very recently, even transparent conducting oxides (TCOs), such as indium-tin-oxide (ITO), have been prepared using suitable KLE templates.59 As one potential application, such porous TCOs (ZnO, etc.) are interesting for use in dye-sensitized solar cells. In general, such porous electrodes cover a variety of potential electro-optical applications, because they are both conducting and transparent. 

In lead zirconate, PbZr03, the larger lead ions are displaced alternately from the cube comer sites to produce an antiferroelectric. This can readily be converted to a ferroelectric by the substitution of Ti4+ ions for some of the Zr4+ ions, the maximum value of permittivity occurring at about the 50 50 mixture of PbZrC>3 and PbTiC>3. The resulting PZT ceramics are used in a number of capacitance and electro-optic applications. The major problem in the preparation of these solid solutions is the volatility of PbO. This is overcome by... 

M Okawara et al., Organic colorants A handbook of data of selected dyes for electro-optical applications, (Oxford Elsevier, 1988). 

Second order materials will be used in optical switching (modulation), frequency conversion (SHG, wave mixing) and electro-optic applications, especially EO modulators (SLM). The applications all rely on the manifestation of... 

Bosch M, Fischer C, Cai C, Liakatas I, Jager M, Bosshard Ch, Gunter P (1999) Photochemical stability of highly nonlinear optical chromophores for electro-optic applications. In Organic thin films for photonics applications. Optical Society of America, Washington DC, p 75... 

Figure 2. Example of a chromophore optimized for electro-optic applications. A PMMA-doped film with this chromophore had = 83 pm V . ...

Optical processing systems are proposed based on relative intensity changes of second harmonic generation in sorbate complexes of p-nitroaniline and 2-methyl-p-nitroaniline in molecular sieve hosts [98]. Optical data storage would be one of a variety of potential electro-optical applications. In addition, molecular optical effects by third harmonic generation are suggested for optical data storage based on the possible formation of bistabilities for the local fields [65,99]. 

Silicon carbide (SiC) is an attractive semiconductor material for high temperature electronic and electro-optic applications. From the device application point of view the thermal conductivity of SiC exceeds that of copper, BeO, A1203 and AIN. The actual value of the thermal conductivity can be varied with polytype and/or doping [1,2]. 

All electronic and electro-optic applications of poly-conjugated systems require the preparation of polymers with high chemical and structural homogeneity. Several optical and electrical properties of conjugated polymers such as their quantum efficiency of electroluminescence or maximum conductivity after doping can be correlated with the concentration of conjugation breaking defects introduced to the polymer upon its preparation. 

Fig. 5 a) General structure of a thermotropic LC with two alkyl chains b) structure of a LC for electro-optical applications with a polar group. 

Functional bi- and tripyridyl-based ruthenium(II)- and iridium(lll)-con-taining polymers for potential electro-optical applications 07CSR618. 

Ferroelectric liquid crystals (FLC) are of great interest due to their fast electro-optical response which is about 1,000 times faster than conventional twisted nematic cells [131]. The geometry used is called a surface stabilized FLC cell which utilizes a very thin gap (=2 pm) to unwind the FLC supramolecular pitch (=1-2 pm) since the bulk FLC materials do not show macroscopic polarization. This very thin gap, however, leads to difficulties in manufacturing large panels and very poor shock resistance. Researchers have proposed the concept of microphase stabilized FLC [79,109, 130] using FLC-coil diblock copolymers for electro-optical applications as shown in Fig. 15. This concept takes advantage of ferroelectric liquid crystallinity and block copolymer microphase separation since the block... 

A Handbook of Data of Selected Dyes for Electro-optical Applications... 

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