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Liquid Crystals and their Application
Russian Journal

Zhidkie kristally i ikh prakticheskoe ispol'zovanie

Жидкие кристаллы и их практическое использование

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Rus Eng


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Zhidk. krist. ikh prakt. ispol'z. = Liq. Cryst. and their Appl., 2015, 15 (3), 64—81.
DOI: 10.18083/LCAppl.2015.3.64

Properties of Nematic Liquid Crystals Doped with CdSe/ZnS Semiconductor Nanoparticales

E. A. Konshina, D. P. Shcherbinin, E.O. Gavrish, I. F. Galin, M. A. Kurochkina

Author affiliations
National Research University of Information Technologies, Mechanics and Optics,
49 Kronverkskii Ave., St. Petersburg, 197101, Russia

The experimental results on the study of nematic liquid crystals (NLC) suspensions based on alkylcyanobiphenyl with positive dielectric anisotropy and doped with the semiconductor quantum dots (QDs) CdSe/ZnS of the core-shell type with the core size of 3,5 and 5 nm are presented. A modification of the dielectric permittivity components of the NLC depending on the nanoparticles concentration is shown. Increasing of the QDs concentration is accompanied by an increase in the conductivity of the suspensions for the frequencies below 1 kHz. Dielectric anisotropy of the suspensions with QDs concentrations less than 0,3 wt. % slightly deviated from its value for the NLC in the frequency range from 1 to 10 kHz. It has been found that the rotational viscosity of the suspension containing 10 wt. % of QDs increased by 2,5 times simultaneously with the ion density increasing. Examination of dynamic characteristics showed that the optical response time decreased 1,5 times with increasing of the QDs concentrations to 0,15 wt. % compared with the initial NLC. The quenching of the luminescence intensity of the NLC, depending on the concentration and the size of the QDs is demonstrated. As well as the management of the QDs luminescence intensity in the homogeneously oriented NLC layer by application of an electric field is shown.

Keywords: nematic liquid crystal, quantum dots, dielectric spectra, dielectric anisotropy, elastic coefficient, rotational viscosity, dynamic characteristics, luminescence

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