Switchable windows

PDLC and NCAP films are just now reaching commercialization. Some applications, such as large area signs and switchable windows, could not be served by previous electro-optic materials. Recent innovations in PDLC films are expanding the possible applications for PDLC materials and improving their overall performance. 

In modem history, particularly in the recent decades, liquid crystals (LCs) have become a very important class of materials. Since the first invention of LC display (LCD), LCs have become the quintessential materials in information displays such as TVs, computer monitors, and digital displays. In the recent development of LC materials, LCs have moved rapidly beyond display applications and are evolving into entirely new scientific frontiers, opening broad avenues for versatile applications such as lasers, photovoltaics, light-emitting diodes, field effect transistors, biosensors, switchable windows, and nanophotonics [1]. AU these applications benefit from LC s unique properties, e.g. self-organization and being able to... 

Other improved polymer electrolytes suitable for room temperature switchable windows include an all-amorphous system formed by the dis-... 

Tremendous activity [33] has characterized the field of research on polymer-dispersed liquid crystals (PDLCs) which are potentially useful for a variety of electrooptical applications including light shutters and switchable windows, displays, and other devices. These materials consist of micrometer-size nematic droplets dispersed in a polymer matrix and their optical response is based on the electrically controlled light-scattering properties of the droplets. 

Polymer-dispersed liquid crystals (PDLCs) is a relatively new class of promising material for many applications such as, switchable windows, display devices, infrared shutters, angular-discriminating filters, thermoelectrooptic switches, memories, gas-flow sensors, optical sensors, and optical gratings etc. These materials are examples of combined application of polymers and liquid crystals and command the attention of the display industry as well as the researchers. These consist of LC droplets which are dispersed in a polymer matrix. These tiny droplet characteristics are responsible... 

In the UK, researchers at Cambridge University have devised a method of growing vertical carbon nanotubes on a flexible plastic substrate which gives scope for further research into potential applications especially where flexibility is a key element of the product design. At Sheffield University the research project involves the dispersion of nano-sized droplets of PEDOT (or other conducting polymers) into a polyethylene oxide polymer electrolyte matrix. Together with a suitable redox couple, where oxidation and reduction are considered together as complementary processes, it is possible to produce efficient, switchable windows for microwaves. 

PEDOT is a widely used / -type semiconductca . Typical applications include hole injection layers in OLEDs and LCD, antistatic coatings, electrically switchable windows, and polymer solar cells. In most of these applications, PEDOT-poly(styrenesulfonic acid) (PEDOT-PSS) copolymer is used because of improved solubility, film forming properties and stability [118]. 

Figure 5.31 Example of a PDLC display in operation as a switchable window...

Polymer-dispersed liquid crystals (PDLCs) are important to liquid-crystal technology. Nematic LC microdroplets are dispersed in a polymer matrix. These films are used similarly to liquid crystal displays such as displays, switchable windows, and light shutters. PDLC devices operate on the principle of electrical modulation of the LC refractive index to match or mismatch the refractive index of an optically transparent, isotropic solid. PDLC films are made between conductive, transparent substrates, and can be switched from being opaque to being transparent with the application of an electric field. Solid state NMR methods have been used to study (PCLCs) and to identify the LC/polymer interface [80,81]. Using NMR one can iden-... 

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