Tri-state switching of a high-order parameter, double-layered guest-host liquid-crystal shutter, doped with the mesogenic molecule 4HPB

ABSTRACT

Dye-doped guest-host liquid crystal (GHLC) light shutters are widely used for privacy protection (windows) and sunlight blocking because of their low power consumption and fast response speed. The mesogenic molecule 4-(4-Heptylphenyl) benzoic acid (4HPB) can form hydrogen bonds with a vertical PI alignment layer to create a superhydrophobic vertical alignment (polyimide) PI layer, which can improve the order parameters of the dye. Because the initial transmittance and contrast of the GHLC are proportional to its own order parameters, the addition of the mesogenic molecule 4HPB can increase both the initial transmittance and contrast of the GHLC significantly. Moreover, the addition of 4HPB can also greatly increase the ion concentration of the GHLC, which introduces an electro-hydrodynamic effect. The GHLC can be switch states between transparent, haze-free dark, and high-haze dark by changing the strength of the applied voltage of appropriate frequency. Double-layered guest-host liquid crystal (DGHLC), doped with mesogenic molecules, are suitable for fast-moving applications (such as cars and airplanes) due to their short response time and high-order parameters.

Graphical abstract

KEYWORDS:

• Liquid crystals
• switchable window
• dichroic dye
• electro-hydrodynamic instability

Disclosure statement

No potential conflict of interest was reported by the authors.

Supplementary material

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Additional information

Funding

This study was supported by Natural Science Foundation of Anhui Province, China (1708085MF150); Distinguished Youth Foundation of Anhui Province (1808085J03) and the Fundamental Research Funds for the Central Universities (Grant No. JZ2018HGPB0276).