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Theoretical study of the optical properties of low voltage stacked cholesteric liquid-crystal displays
Dalarna University.
Dalarna University.
Dalarna University.
2004 (English)In: Asia Display/IMID'04, South Korea, 2004, 202-204 p.Conference paper (Refereed)
Abstract [en]

We study theoretically optical properties of thin layered stacked monochrome cholesteric liquid-crystal displays. Thin thickness of the layers (~1 µm) allows us appreciably to reduce driving voltage and use such displays in smart cards. Good selective reflection is achieved due to stacked structure. Dependence of the reflectivity of this type of displays on the quality of the layers, their thickness, and liquid crystal birefringence is investigated.

Place, publisher, year, edition, pages
2004. 202-204 p.
Keyword [en]
cholesteric liquid crystal, LCD, bistability
National Category
Computational Mathematics Atom and Molecular Physics and Optics
Research subject
Information Systems
URN: urn:nbn:se:uu:diva-107455OAI: oai:DiVA.org:uu-107455DiVA: diva2:229385
Available from: 2009-08-12 Created: 2009-08-12 Last updated: 2009-08-13
In thesis
1. Optical Characterization and Optimization of Display Components: Some Applications to Liquid-Crystal-Based and Electrochromics-Based Devices
Open this publication in new window or tab >>Optical Characterization and Optimization of Display Components: Some Applications to Liquid-Crystal-Based and Electrochromics-Based Devices
2009 (English)Doctoral thesis, comprehensive summary (Other academic)
Abstract [en]

This dissertation is focused on theoretical and experimental studies of optical properties of materials and multilayer structures composing liquid crystal displays (LCDs) and electrochromic (EC) devices.

By applying spectroscopic ellipsometry, we have determined the optical constants of thin films of electrochromic tungsten oxide (WOx) and nickel oxide (NiOy), the films’ thickness and roughness. These films, which were obtained at spattering conditions possess high transmittance that is important for achieving good visibility and high contrast in an EC device.

Another application of the general spectroscopic ellipsometry relates to the study of a photo-alignment layer of a mixture of azo-dyes SD-1 and SDA-2. We have found the optical constants of this mixture before and after illuminating it by polarized UV light. The results obtained confirm the diffusion model to explain the formation of the photo-induced order in azo-dye films.

We have developed new techniques for fast characterization of twisted nematic LC cells in transmissive and reflective modes. Our techniques are based on the characteristics functions that we have introduced for determination of parameters of non-uniform birefringent media. These characteristic functions are found by simple procedures and can be utilised for simultaneous determination of retardation, its wavelength dispersion, and twist angle, as well as for solving associated optimization problems.

Cholesteric LCD that possesses some unique properties, such as bistability and good selective scattering, however, has a disadvantage – relatively high driving voltage (tens of volts). The way we propose to reduce the driving voltage consists of applying a stack of thin (~1µm) LC layers.

We have studied the ability of a layer of a surface stabilized ferroelectric liquid crystal coupled with several retardation plates for birefringent color generation. We have demonstrated that in order to accomplish good color characteristics and high brightness of the display, one or two retardation plates are sufficient.

Place, publisher, year, edition, pages
Uppsala: Acta Universitatis Upsaliensis, 2009. 64 p.
Digital Comprehensive Summaries of Uppsala Dissertations from the Faculty of Science and Technology, ISSN 1651-6214 ; 664
ellipsometry, liquid crystal, LCD, optical anizotropy, electrochromic, inverse problems
National Category
Atom and Molecular Physics and Optics Atom and Molecular Physics and Optics Computational Mathematics
Research subject
Solid State Physics; Information Systems
urn:nbn:se:uu:diva-107429 (URN)978-91-554-7583-3 (ISBN)
Public defence
2009-09-24, 2001, Ångströmlaboratoriet, Lägerhyddsvägen 1, Uppsala, 13:15 (English)
Available from: 2009-09-03 Created: 2009-08-11 Last updated: 2009-09-03Bibliographically approved

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Valyukh, Iryna
Computational MathematicsAtom and Molecular Physics and Optics

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