Dielectric properties of two high birefringence liquid crystal mixtures in the Sub-THz band

ABSTRACT

In order to produce liquid crystal (LC) with high birefringence (Δn) in the THz band, eight LC monomers were designed and synthesized. We formulate two mixtures (LC S200-2 and E7-2) by adding eight LC monomers to two commercial LCs (S200 and E7), respectively. The dielectric constants of the mixture LCs were measured using the frequency selective surface (FSS) in the region from 90 to 140 GHz. We compare the simulated results with the experimental measurements and determine the dielectric constants of the LCs. The dielectric anisotropy (Δε) of the nematic S200-2 and E7-2 LC mixtures are 16.4% and 16.3% higher than that of the commercial S200 and E7 LCs, respectively. The results show the frequency tunability of the two LC mixtures is greater than that of the commercial LCs.

GRAPHICAL ABSTRACT

The dielectric anisotropy (Δε) of these standard NLCs show a relatively low value in the THz range. In this paper, eight NLC monomers with large birefringence were synthesized. we presented two LC mixtures S200-2 and E7-2 by adding eight liquid crystal monomers to commercial NLCs: SLC103014-200 (S200) (Shijiangzhuang Chengzhi Yonghua Display Material Co, Ltd.) and E7 (HCCH). We measured the dielectric constant of LCs using the frequency selective surface（FSS). The results show that the dielectric anisotropy of the nematic LC mixtures S200-2 and E7-2 are 16.4% and 16.3% higher than that of the commercial S200 and E7 LCs, respectively.

KEYWORDS:

• Liquid crystals
• large birefringence
• dielectric anisotropy
• frequency selective surface

Disclosure statement

No potential conflict of interest was reported by the authors.

Additional information

Funding

This work is supported by the National Natural Science Foundation of China (Grant No. 61871171 and 51607050).