Influence of Periodic Non-Uniformities of Well-Structured Sapphire Surface by LIPSS on the Alignment of Nematic Liquid Crystal
In this study, we report on the alignment properties of nematic liquid crystals on various transparent structured sapphire layers formed by laser-induced periodic surface structures (LIPSS). One-dimensional LIPSS (1D-LSFL) are generated by infrared femtosecond laser pulses along parallel lines cover...
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MDPI AG
2022-02-01
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| Series: | Nanomaterials |
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| Online Access: | https://www.mdpi.com/2079-4991/12/3/508 |
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| author | Igor Gvozdovskyy Zoya Kazantseva Simon Schwarz Ralf Hellmann |
| author_facet | Igor Gvozdovskyy Zoya Kazantseva Simon Schwarz Ralf Hellmann |
| author_sort | Igor Gvozdovskyy |
| collection | DOAJ |
| description | In this study, we report on the alignment properties of nematic liquid crystals on various transparent structured sapphire layers formed by laser-induced periodic surface structures (LIPSS). One-dimensional LIPSS (1D-LSFL) are generated by infrared femtosecond laser pulses along parallel lines covering an area of 5 × 5 mm<sup>2</sup>, with a line spacing that is varied between 7 and 17 µm. These periodic structures, employed as alignment layers, have a spatial periodicity of about 980 nm, a modulation depth of about 100 nm, and exhibit a high quality due to being characterized by a high degree of homogeneity and parallelism of the structured features. It is found that such alignment layers of the sapphire surface lead to a decreasing azimuthal anchoring energy, when the width of the unstructured gap is increased. Modifying the sapphire surface by an ITO-coating with further deposition of a polyimide film increases the azimuthal anchoring energy by a factor of about four up to <i>W<sub>φ</sub></i> ~ 4.25 × 10<sup>−6</sup> J/m<sup>2</sup>, when the minimum width of the unstructured gap is 7 µm. Comprehensive measurements and comparisons of the azimuthal anchoring energy as well as the pretilt angle for the 1D-LSFL, unstructured gaps, and entire areas depending on the width of unstructured gaps are presented and discussed. |
| first_indexed | 2024-03-09T23:23:23Z |
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| issn | 2079-4991 |
| language | English |
| last_indexed | 2024-03-09T23:23:23Z |
| publishDate | 2022-02-01 |
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| series | Nanomaterials |
| spelling | doaj.art-64127dd2889f4b31b09fd673a0101d022023-11-23T17:21:54ZengMDPI AGNanomaterials2079-49912022-02-0112350810.3390/nano12030508Influence of Periodic Non-Uniformities of Well-Structured Sapphire Surface by LIPSS on the Alignment of Nematic Liquid CrystalIgor Gvozdovskyy0Zoya Kazantseva1Simon Schwarz2Ralf Hellmann3Institute of Physics of the National Academy of Sciences of Ukraine, Prospekt Nauki 46, 03028 Kyiv-28, UkraineV.E. Lashkaryov Institute of Semiconductor Physics of the National Academy of Sciences of Ukraine, Prospekt Nauki 45, 03028 Kyiv-28, UkraineApplied Laser and Photonics Group, University of Applied Sciences, Würzburger Straße 45, 63743 Aschaffenburg, GermanyApplied Laser and Photonics Group, University of Applied Sciences, Würzburger Straße 45, 63743 Aschaffenburg, GermanyIn this study, we report on the alignment properties of nematic liquid crystals on various transparent structured sapphire layers formed by laser-induced periodic surface structures (LIPSS). One-dimensional LIPSS (1D-LSFL) are generated by infrared femtosecond laser pulses along parallel lines covering an area of 5 × 5 mm<sup>2</sup>, with a line spacing that is varied between 7 and 17 µm. These periodic structures, employed as alignment layers, have a spatial periodicity of about 980 nm, a modulation depth of about 100 nm, and exhibit a high quality due to being characterized by a high degree of homogeneity and parallelism of the structured features. It is found that such alignment layers of the sapphire surface lead to a decreasing azimuthal anchoring energy, when the width of the unstructured gap is increased. Modifying the sapphire surface by an ITO-coating with further deposition of a polyimide film increases the azimuthal anchoring energy by a factor of about four up to <i>W<sub>φ</sub></i> ~ 4.25 × 10<sup>−6</sup> J/m<sup>2</sup>, when the minimum width of the unstructured gap is 7 µm. Comprehensive measurements and comparisons of the azimuthal anchoring energy as well as the pretilt angle for the 1D-LSFL, unstructured gaps, and entire areas depending on the width of unstructured gaps are presented and discussed.https://www.mdpi.com/2079-4991/12/3/508aligning layersnematic liquid crystalsazimuthal anchoring energystructured sapphire layerslaser-induced periodic surface structuring |
| spellingShingle | Igor Gvozdovskyy Zoya Kazantseva Simon Schwarz Ralf Hellmann Influence of Periodic Non-Uniformities of Well-Structured Sapphire Surface by LIPSS on the Alignment of Nematic Liquid Crystal Nanomaterials aligning layers nematic liquid crystals azimuthal anchoring energy structured sapphire layers laser-induced periodic surface structuring |
| title | Influence of Periodic Non-Uniformities of Well-Structured Sapphire Surface by LIPSS on the Alignment of Nematic Liquid Crystal |
| title_full | Influence of Periodic Non-Uniformities of Well-Structured Sapphire Surface by LIPSS on the Alignment of Nematic Liquid Crystal |
| title_fullStr | Influence of Periodic Non-Uniformities of Well-Structured Sapphire Surface by LIPSS on the Alignment of Nematic Liquid Crystal |
| title_full_unstemmed | Influence of Periodic Non-Uniformities of Well-Structured Sapphire Surface by LIPSS on the Alignment of Nematic Liquid Crystal |
| title_short | Influence of Periodic Non-Uniformities of Well-Structured Sapphire Surface by LIPSS on the Alignment of Nematic Liquid Crystal |
| title_sort | influence of periodic non uniformities of well structured sapphire surface by lipss on the alignment of nematic liquid crystal |
| topic | aligning layers nematic liquid crystals azimuthal anchoring energy structured sapphire layers laser-induced periodic surface structuring |
| url | https://www.mdpi.com/2079-4991/12/3/508 |
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