Electrohydrodynamic instabilities for smart window applications

ABSTRACT

Electrohydrodynamic instability in liquid crystals is investigated for smart window applications. By comparing different species of ions doped in liquid crystals, the positive charge of the organic part of the salt is the origin of the generation of vortexes and leads to the activation of electrohydrodynamic instability. By replacing conventional electrolytes with zwitterions, compared to electrolyte-doped liquid crystals, zwitterion-doped liquid crystals have a broader range of optimal frequency from 10 Hz to 5 kHz. The devices can be switched between the transparent state and the light scattering state for thousands of times without showing any fatigue. A scattering colour is obtained by incorporating a dichroic dye in zwitterion-doped liquid crystal. A patterned device is designed and shows a localised light scattering and colour effect in the presence of an electric field. This strategy will make electrohydrodynamic instability possible to enrich the applications across smart windows, projection screens and information displays.

GRAPHICAL ABSTRACT

KEYWORDS:

• Electrohydrodynamic instability
• zwitterion
• dichroic dye
• smart window
• information display

Acknowledgements

We thank Prof. Albert Schenning, Prof. Dirk Broer and Dr Danqing Liu for discussions. The results presented are part of research programs financed by the National Natural Science Foundation of China (51561135014, U1501244), Guangdong Innovative Research Team Program (No. 2013C102), the Program for Changjiang Scholars and Innovative Research Teams in Universities (No. IRT_17R40), Science and Technology Project of Guangdong Province (No. 2018A050501012), Guangdong Provincial Key Laboratory of Optical Information Materials and Technology (No. 2017B030301007), MOE International Laboratory for Optical Information Technologies and the 111 Project. Additional information is available in the supplementary materials and from the authors.

Disclosure statement

No potential conflict of interest was reported by the authors.

Supplementary material

Supplemental data for this article can be accessed here.

Additional information

Funding

This work was supported by the National Natural Science Foundation of China [51561135014, U1501244];Guangdong Provincial Key Laboratory of Optical Information Materials and Technology [No. 2017B030301007]; the Program for Changjiang Scholars and Innovative Research Teams in Universities [No. IRT_17R40];Science and Technology Project of Guangdong Province [No. 2018A050501012]; and Guangdong Innovative Research Team Program [No. 2013C102].