Effects of Pentacene on the Properties of Negative Anisotropy Nematic Liquid Crystal in Vertical Alignment Cell

Abstract

This paper proposes a vertical alignment cell based on a negative anisotropy nematic liquid crystal doped with pentacene. The device shows a lower operating voltage and faster dynamic response time compared to a vertical alignment cell without pentacene. The dielectric anisotropy, elastic constant and rotational viscosity of the pentacene-doped liquid crystal have been measured, and the results show that the low operating voltage and fast response time of the pentacene-doped vertical alignment cell is due to the increase of dielectric anisotropy and the decrease of rotational viscosity. Also, the frequency dependent dielectric relaxations of both the normal and the pentacene-doped nematic liquid crystal have been measured. As the result, it is shown that the pentacene lowers the dielectric response, which in turn reduces the rotational viscosity.