Super-Fast Switching of Twisted Nematic Liquid Crystals on 2D Single Wall Carbon Nanotube Networks



We have developed a high performance liquid crystal (LC) alignment layer of ultra-thin single wall carbon nanotubes (SWNTs) and a conjugated block copolymer nanocomposite that is solution-processible for conventional twisted nematic (TN) LC cells. The alignment layer is based on the non-destructive solution dispersion of nanotubes with a poly(styrene-b- paraphenylene) (PS-b-PPP) copolymer and subsequent spin coating, followed by conventional rubbing without a post-annealing process. Topographically grooved nanocomposite films with two dimensionally (2D) networked SWNTs embedded in a block copolymer matrix were created using a rubbing process in which bundles of SWNTs on the composite surface were effectively removed. The LCs were well aligned with a stable pre-tilt angle of approximately 2° on our extremely transparent nanocomposite, which gave rise to superfast switching of the TN LC molecules that was approximately 3.8 ms, or four times faster than that on a commercial polyimide layer. Furthermore, the TN LCD cells containing our SWNT nanocomposite alignment layers exhibited low power operation at an effective switching voltage amplitude of approximately 1.3 V without capacitance hysteresis.