Polyimide-free homogeneous photoalignment induced by polymerisable liquid crystal containing cinnamate moiety

ABSTRACT

We designed and synthesised a reactive mesogen (CRM) containing cinnamate moiety in the core and two acrylate groups at both ends. The structure was characterised by ¹H NMR and FT-IR, and its liquid crystalline property was investigated by DSC and POM. The compound showed a nematic phase between 175.2 – 97.5 ^oC, followed by a smectic C phase between 97.5 and 57.9 ^oC during the cooling cycle. We proposed a fabrication method to achieve uniaxial homogeneous alignment of liquid crystals by irradiating the CRM-doped LC mixture in a sandwich cell of in-plane switching mode (CRM-IPS) with linearly polarised ultraviolet light. The results indicated that the CRM-IPS cell showed excellent initial dark state with a good alignment state, electro-optical performance and durability. This confirmed that the photo-induced alignment of LCs by CRM possesses outstanding alignment capability compared to the conventional rubbed polyimide alignment layer. We expect that this fabrication method is a promising candidate for cost-effective, green-manufacturing, and high-quality alignment method for the manufacturing of high-resolution liquid crystal displays (LCDs).

Graphical Abstract

KEYWORDS:

• Reactive mesogen
• photoalignment
• homogeneous alignment
• in-plane switching

Disclosure statement

No potential conflict of interest was reported by the authors.

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Funding

This work was supported by the Basic Science Research Program through the National Research Foundation of Korea (NRF) under Grant funded by the Ministry of Education [2013R1A1A2063696]; Institute for Information & Communications Technology Promotion (IITP) under Grant funded by the Korea Government (MSIP) [R7520-16-0010]; Key Projects of Guizhou Provincial Science and Technology Foundation [[2016]1419].