Electro-optic bistability in organosiloxane bimesogenic liquid crystals

D. J. Gardiner, C. J. Davenport, J. Newton, H. J. Coles
2006 Journal of Applied Physics  
In this paper we report the electro-optic characterization of two homologous series of low molar mass bimesogenic siloxane-containing liquid crystals. The materials used have two alkoxycyanobiphenyl mesogenic units with variable alkyl chain joined by a two-or five-siloxane moiety and all exhibit stable smectic A mesophases over wide temperature ranges ͑up to 100°C wide͒. Due to their inherent ruggedness these materials have potential for use in polarizer-free, bistable, scattering display and
more » ... orage devices. The bistable modes are at low and high frequencies. The low frequency mode ͑write͒ is a highly scattering focal conic texture resulting from electrohydrodynamic instabilities while the high frequency mode ͑erase͒ is a clear state due to dielectric reorientation of the material. Both modes are preserved upon removal of the applied electric field. We present threshold voltages as a function of temperature, frequency, and cell thickness and response times as a function of voltage for each of the bistable modes. We find reduced threshold voltages ͑5 ഛ V th ഛ 12 V / m͒ and response times that are strongly dependent on applied voltage ͑50 msഛ ഛ 10 s͒. These operating conditions would suggest that these materials are particularly suitable for slow update, large area, low power information panels and displays.
doi:10.1063/1.2203391 fatcat:5tnqdbugbnfchbkdmg6scibhuu