29‐3: Highly Versatile and Stable Photoalignment Process for AMLCDs

McGinty, Colin; Wang, Junren; Finnemeyer, Valerie; Reich, R.; Clark, Harry; Berry, Shaun; Bos, Philip J.

doi:10.1002/sdtp.12576

Cited by 2 publications

(3 citation statements)

References 8 publications

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“…We conclude that for thin LC films, the anchoring strength is sufficient even with very thin photoalignment layers. Concentrations as low as 0.1% in DMF have been shown to work well for photoalignment [28]. Hence, the concentration of BY can be selected depending on the target application.…”

Section: Discussionmentioning

confidence: 99%

A practical guide to versatile photoalignment of azobenzenes

et al. 2020

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Photoalignment refers to a technique for the definition of the orientation of liquid crystals using light. The approach is based on the use of materials that either absorb or trigger a chemical reaction with an anisotropy that depends on the polarisation of light. Azobenzenes are a wellestablished for aligning liquid crystals in research applications. Despite their popularity, only few details of the process are publicly available. We consider here the optimisation of the photoalignment process using the dichroic dye Brilliant Yellow. Its solubility in various solvents; the alignment quality as a function of exposure time and intensity; the influence of humidity at various stages; and the stability of the process in the presence of environmental light are investigated. Additionally, the dichroic dyes Congo Red and Chrysophenine are tested to increase the portfolio of available photoalignment materials.

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Section: Discussionmentioning

confidence: 99%

A practical guide to versatile photoalignment of azobenzenes

et al. 2020

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“…Life tests re-expose the LC-filled cells to linearly polarized blue light at 45° with respect to the original photo-alignment process. Photo-bleaching re-exposes the cells with un-polarized blue light to eliminate the photosensitivity of the azo dye layer [ 10 , 11 ] because the brilliant yellow molecules re-orient along the un-polarized light propagation direction where no light absorption occurs and the molecules are at rest. If the monomer was not polymerized on (or close to) the surface, the resulting cells would show: (1) re-alignment with life test and/or photo-bleaching, (2) some light scattering observation because of the network through bulk, or (3) increased threshold voltage as indicated by the T/V curve after UV polymerization.…”

Section: Methodsmentioning

confidence: 99%

“…To simplify the process, V. Finnemeyer et al [ 6 ] proposed that a small amount of reactive monomer added to the liquid crystal host could provide excellent stabilization of the alignment by phase separation. Additionally, C. McGinty et al [ 10 , 11 ] showed that the underlying azodye layer can be photo-bleached to eliminate its visible absorption as well as its ability to re-orient further.…”

Section: Introductionmentioning

confidence: 99%

Process for a Reactive Monomer Alignment Layer for Liquid Crystals Formed on an Azodye Sublayer

et al. 2018

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In this work, the detailed studies of surface polymerization stabilizing liquid crystal formed on an azodye sublayer are presented. The surface localized stabilization is obtained by free-radical polymerization of a dilute solution of a bi-functional reactive monomer (RM) in a liquid crystal (LC) solvent. To optimize the process for surface localized stabilization, we investigate the effects of several process parameters including RM concentration in LC hosts, the types of materials (either RM or LC), the photo-initiator (PI) concentration, ultra-violet (UV) polymerization intensity, and the UV curing temperature. The quality of surface localized stabilization is characterized and/or evaluated by optical microscopy, electro-optical behavior (transmission/voltage curve), the life test, and photo-bleaching. Our results show that, by carefully selecting materials, formulating mixtures, and controlling the polymerizing variables, the RM polymerization can be realized either at the surface or through the bulk. Overall, the combination of surface localized stabilization and photo-alignment offers an elegant and dynamic solution for controlling the alignment for LC, which could play a profound role in almost all liquid crystal optical devices.

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29‐3: Highly Versatile and Stable Photoalignment Process for AMLCDs

Cited by 2 publications

References 8 publications

A practical guide to versatile photoalignment of azobenzenes

A practical guide to versatile photoalignment of azobenzenes

Process for a Reactive Monomer Alignment Layer for Liquid Crystals Formed on an Azodye Sublayer

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