High Birefringence and Low Viscosity Liquid Crystals with Negative Dielectric Anisotropy Sebastian Gauza 1 , Przemyslaw Kula 2 , Xiao Liang 3 , Shin-Tson Wu 1 , and Roman Da ˛ browski 2 1 College of Optics and Photonics, University of Central Florida, Orlando, Florida, USA 2 Institute of Chemistry, Military University of Technology, Warsaw, Poland 3 Department of Chemistry, Tsinghua University, Beijing, China Fast response time is critical for reducing the image blurs in LCD TVs. A straight- forward approach is to use thin cell with a high birefringence and low viscosity liquid crystal material. We have synthesized and evaluated the physical properties of some high birefringence, laterally difluorinated terphenyl compounds and mixtures. These mixtures exhibit a high birefringence (Dn  0.24) in the visible spectral range and a relatively low viscosity. When doped in commercial mixtures, the difluoro terphenyl compounds enhance the mixture’s birefringence while caus- ing almost no penalty to the rotational viscosity. These mixtures are particularly attractive for thin cell LCDs to achieve fast response time. Keywords: fluorinated terphenyl; high birefringence; liquid crystals; response time; vertical alignment 1. INTRODUCTION Nematic liquid crystals (LCs) with a negative dielectric anisotropy (De < 0) play an important role in many electro-optical devices. For example, a vertical alignment (VA) cell using a negative De LC exhibits a high contrast ratio [1] which is particularly attractive for video applications. Besides high contrast ratio, fast response time is very desirable for almost all the LC devices, especially for reducing the motion blurs of liquid crystal display televisions (LCD TVs) and the This work is partially supported by NATO Programme Security Through Science, Collaborative Linkage Grant No. CBP.EAP.CLG 983701. Address correspondence to Shin-Tson Wu, College of Optics and Photonics, 4000 Central Florida Blvd., Orlando 32816, United States. E-mail: swu@mail.ucf.edu Mol. Cryst. Liq. Cryst., Vol. 509, pp. 47=[789]–59=[801], 2009 Copyright # Taylor & Francis Group, LLC ISSN: 1542-1406 print=1563-5287 online DOI: 10.1080/15421400903054006 47=[789]