ELECTRICALLY INDUCED OPTICAL AND STRUCTURAL RESPONSE OF CHOLESTERIC AND NEMATIC DROPLETS WITH CONICAL BOUNDARY CONDITIONS

摘要

The electro-optical response of polymer dispersed liquid crystals films has been studied. The polymer specifies the conical boundary conditions for the cholesteric and nematic LC. It is shown that for the cholesteric-based film with the relative chiral parameters of droplets equal to 0.32, control voltages are less than control voltages for the nematic-based film. The threshold voltages are 2.7 V and 4.9 V, and the saturation voltages are 7.3 V and 9.0 V for the cholesteric-based and nematic-based films, respectively. At saturation voltage, the light transmission of these films is over 80 %. The cholesteric-based film turns into a strong scattering state during 85 ms after switching off voltage, while the nematic-based film turns into initial scattering state during a few days. Significant differences in the electro-optical response of the studied films were explained using an examination of electrically induced transformations of the orientational structures formed in nematic and cholesteric droplets. Polymer dispersed cholesteric liquid crystals with conical boundary conditions are prospectful for the development of devices with low-voltage control.