Fast electro-optical switching with banana-shaped liquid crystals (WPC.5325)
2004 - 08 / 2005
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One of the main problems related to application of liquid crystals in large flat panel displays for computer monitors and color televisions is the relatively slow switching behaviour of the commonly used nematic liquid crystals. Ferroelectric crystals based on the chiral smectic-C phase are capable of much faster switching. However there are still many problems with device construction using these materials. The relatively new antiferroelectric crystals posess even better material properties. Very recently completely new liquid crystalline phases were obtained from bent or banana-shaped molecules, which are capable of fast antiferroelectric optical switching. Structurally related bent dimer liquid crystals were also found to exhibit fast antiferroelectric switching behaviour. Application of these compounds is hampered by the high temperatures of liquid crystalline phases. In addition, they contain chemically instable imine bonds. Based on our expertise with dimer and trimer liquid crystals, we propose to investigate dimer and trimer liquid crystals that exhibit fast antiferroelectric optical switching. Our research will focus on the one hand on finding structural requirements for obtaining these interesting phases in order to obtain materials that can be used at room temperatures and that are chemically stable. On the other hand, in close cooperation with Philips, interesting materials will be tested in experimental cells to study their (anti)ferroelectric switching behavior and electrooptical response as a function of time and applied voltage. In addition to the monomolecular compounds, polymeric materials based on the above mentioned dimer and trimer liquid crystals will be prepared. It is expected that even polymers with these phases exhibit fast enough switching for display applications. This opens possibilities for new and cheap display manufacturing technologies and new applications.