Effects of Molecular Configuration and Driving Architecture on Electro-Optical Properties of Cholesteric Liquid Crystal Displays

The effects of molecular configuration and driving architecture on the electro-optical properties of cholesteric liquid crystal (ChLC) displays are demonstrated. Two kinds of ChLC cells, composed by mixing the chiral dopant with the positive nematic LC (P-ChLC cell) and with the negative nematic LC (N-ChLC cell), are fabricated in order to make a detailed investigation. Compared with the conventional P-ChLC cell driven by the uniform vertical electric fields, the N-ChLC cell driven by the in-plane switching electric fields shows a higher output light transmittance and a more stable helical molecular configuration, which is attributed to the fact that the focal conic configuration does not exist in the N-ChLC cell. In addition, via the three-terminal-electrode driving architecture, a faster switching response (5.2 ms) of the N-ChLC cell at a low driving voltage is successfully achieved. This study not only exhibits the difference in the electro-optical properties of the P-ChLC and N-ChLC cells, but also provides a driving method for the N-ChLC cell to enhance its electro-optical performance, which is beneficial to the development of fast dynamic optical devices.