Abstract:

Chiral nematic liquid crystals possess a self-assembled helical structure and exhibit unique selective reflection in visible and infrared light regions. Their optical properties can be electrically tuned.  The tuning involves the unwinding and restoring the helical structure.  We carried out an experimental study on the mechanism of the restoration of the helical structure.  We constructed chiral nematic liquid crystals with variable elastic constants by doping bent-dimers and studied their impact on the restoration. With matched twist and bend elastic constants, the helical structure can be restored dramatically fast from the field-induced homeotropic state.  Furthermore, defects can be eliminated to produce perfect planar state which exhibits high selective reflection.

报告人简介:

Yang received his Bachelor Degree and Ph.D. (1989) in Physics from Tsinghua University and University of Hawaii, respectively. Now he is a member of the Chemical Physics graduate faculty within Liquid Crystal Institute (LCI). His specialities include cholesteric liquid crystals, liquid crystal/polymer composites and electro-optic devices. He is one of the co-inventors of bistable cholesteric display (BCD) technology, currently the world's most promising technology for electronic paper.