Voltage holding properties of bend liquid crystal cells with treatments for bend alignment stabilisation

Abstract

We investigated the voltage holding property of cells with additional fabrication processes for the formation of high and low pretilt angle regions within a dot for achieving a smooth splay-to-bend transition and of π-cells with a polymer network in a liquid crystal (LC) layer to stabilise a bend state. The pretilt angle could be adjusted by irradiation of deep ultraviolet (UV) light to a vertical alignment polyimide layer. The voltage holding ratio (VHR) was above 97% even with irradiation with deep UV light of 10 J/cm². On the contrary, the VHR was decreased with increasing concentration of photoinitiator, which was added to LC mixture to form the polymer network. The VHR was 90% at the concentration of 0.3 wt%. The results indicate that the formation of the high and low pretilt angle regions within a dot is very useful from the point of reliability of the π-cell.

Keywords:

• π-cell
• voltage holding ratio
• pretilt angle