Stabilisation of reverse twisted nematic structure by forming polymer matrix in the vicinity of the alignment layer

ABSTRACT

Reverse Twisted Nematic (RTN) LCDs, which use the liquid crystalline materials twisting opposite from the one for usual TN-LCDs, have been reported to be driven by low driving voltage. RTN molecular arrangement can be formed by applying electric voltage to the splay twist state. The formed RTN state can be maintained tentatively, however, returns into splay twist state gradually without applied voltage. For stabilisation of RTN state, polymer matrix formation in the whole LC region was effective but caused driving voltage to increase. The usage of high pretilt angle alignment layers and the introduction of wall structures into LC layer were proposed. However, these methods had the defects like low transmittance and the complicated procedures, respectively. In this article, it is reported that RTN state can be stabilised by the polymer matrix formation just in the vicinity of alignment layer. This phenomenon is considered to be the first successful example in which the LC molecular arrangement twisting opposite from the intrinsic twist direction can be stabilised by fixing the structure near alignment layer surface. By this method, the usage of RTN-LCDs of low driving voltage can be realised.

Graphical Abstract

KEYWORDS:

• Twisted nematic
• reverse TN
• low driving voltage
• polymer stabilisation

Acknowledgments

The authors are thankful to Merck Corporation for providing LC materials, and to the JNC Corporation for providing polyimide materials.

Disclosure statement

No potential conflict of interest was reported by the author(s).