Reducing driving voltage and securing electro-optic reliability of in-plane switching liquid crystal display by applying polysulfone photoalignment layer with photo-reactive mesogens

Abstract

Newly synthesised photocurable polysulfone (PSCMh) was applied as a photoalignment layer of in-plane switching liquid crystal display (IPS LCD). When the linear polarised ultraviolet light (LPUVL) was irradiated on the typical calamitic nematic liquid crystals on the PSCMh alignment layer, the liquid-crystal director was aligned perpendicular to the LPUVL. Based on the experimental results, it was realised that IPS LCD photoaligned by PSCMh with additional polymer layer associated with reactive mesogen (RM) showed a low driving voltage with reduction of 0.2 V compared to the rubbed cell and also excellent electro-optic reliability such as alignment stability, residual direct current and voltage holding ratio compared to the purely photoaligned cell. Therefore, it was concluded that the polymer stabilisation of PSCMh with RM was effective for improving IPS LCD performances.

Keywords:

• photocrosslinkable polysulfone
• in-plane switching cell
• reactive mesogen
• electro-optic characteristics

Funding

This research was supported by BK Plus through the National Research Foundation of Korea (NRF) funded by the Ministry of Education, Science and Technology (MEST). One of us (X.-D. Li) acknowledges the National Science Foundation of Hubei Province [2008CDB251] and the Scientific Research Foundation for Returned Overseas Chinese Scholars of the Ministry of Education [BZY07001].