High-quality alignment of nematic liquid crystals using periodic nanostructures created by nonlinear laser lithography

Date

2018-10-01

Author

Pavlov, Ihor
Rybak, A. S.
Dobrovolskiy, A. M.
Kadan, V. M.
Blonskiy, I. V.
Kazantseva, Z. I.
Gvozdovskyy, I. A.

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It is well known that today two main and well studied methods for alignment of liquid crystals has been used, namely: rubbing and photoalignment technologies, that lead to the change of anisotropic properties of aligning layers and long-range interaction of the liquid crystal molecules in a mesophase. In this manuscript, we use the nonlinear laser lithography technique, which was recently presented as a fast, relatively low-cost method for a large area micro and nanogrooves fabrication based on laser-induced periodic surface structuring, as a new perspective method of the alignment of nematic liquid crystals. 920 nm periodic grooves were formed on a Ti layer processed by means of the nonlinear laser lithography and studied as an aligning layer. Aligning properties of the periodic structures of Ti layers were examined by using a combined twist LC cell. In addition, the layer of the nanostructured Ti was coated with an oxidianiline-polyimide film with annealing of the polymer film followed without any further processing. The dependence of the twist angle of LC cells on a scanning speed and power of laser beam during processing of the Ti layer was studied. The azimuthal anchoring energy of Ti layers with a periodic nanostructure was calculated. The maximum azimuthal anchoring energy for the nanostructured Ti layer was about 4.6 x 10(-5) J/m(2), which is comparable to the photoalignment technology. It was found that after the deposition of a polyimide film on the periodic nanostructured Ti layer, the gain effect of the azimuthal anchoring energy to -1 x 10(-4) J/m(2) is observed. Also, AFM study of aligning surfaces was carried out.

Subject Keywords

Aligning layers, Azimuthal anchoring energy, Polyimide, Nematic liquid crystals, Nonlinear laser lithography, Nanostructured titanium layers

URI

https://hdl.handle.net/11511/56218

Collections

Department of Physics, Article