Wide temperature range of an electrically tunable selective reflection of light by oblique helicoidal cholesteric |
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Authors: | Mateusz Mrukiewicz Olena S Iadlovska Greta Babakhanova Simon Siemianowski Sergij V Shiyanovskii |
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Institution: | 1. Advanced Materials and Liquid Crystal Institute, Kent State University, Kent, OH, USA;2. Institute of Applied Physics, Military University of Technology, Warsaw, Poland https://orcid.org/0000-0002-0212-4520;3. Department of Physics, Kent State University, Kent, OH, USA https://orcid.org/0000-0002-8239-6859;4. Chemical Physics Interdisciplinary Program, Kent State University, Kent, OH, USA https://orcid.org/0000-0002-5027-5673;5. Performance Materials Division, Merck KGaA, Darmstadt, Germany;6. Chemical Physics Interdisciplinary Program, Kent State University, Kent, OH, USA https://orcid.org/0000-0003-0394-1183 |
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Abstract: | ABSTRACTOblique helicoidal cholesteric liquid crystals (ChOH) offer an unprecedented opportunity to tune selective reflection of light in a broad spectral range from ultraviolet to infrared by an electric field. The major problem is that the temperature range of stable ChOH is typically above the room temperature and is relatively narrow, a few degrees. In this work, we demonstrate that by using a mixture of flexible dimeric and rod-like molecules, one can significantly expand the temperature range of intense Bragg reflection, from 16°C to 27°C. We demonstrate that the selective reflection peak, reflection intensity, bandwidth and threshold electric field are all temperature dependent and discuss the associated mechanisms. The results show that both the electric field and temperature can be used to tune the structural colour of oblique helicoidal cholesteric structures. The proposed material can be used in switchable optical devices based on liquid crystals, such as light modulators, indoor smart windows, and filters. |
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Keywords: | colour tuning chiral nematic oblique helicoid electrooptics twist-bend nematic |
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