Electro-Optical and Photo Stabilization Study of Nematic Ternary Mixture.

Aleksandra Kalbarczyk,Noureddine Bennis,Leszek R Jaroszewicz,Przemysław Kula,Jakub Herman

doi:10.3390/ma14092283

Aleksandra Kalbarczyk, Noureddine Bennis + Show 3 more

Open Access

https://doi.org/10.3390/ma14092283

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Abstract

Liquid crystal materials composed of mixed nematic compounds find broad use in liquid crystal displays and photonic applications. A ternary mixture formed from three different nematic compounds shows peculiar behavior such as tunable electro-optical properties dependent on the frequency of the driving voltage. The paper presents an analysis of the response time and phase retardation of a frequency tunable nematic liquid crystal mixture (under code name 5005). This material possesses high birefringence (Δn = 0.32 at 633 nm) as well as high dielectric anisotropy (Δε = 6.3 at 100 Hz). The unique property of the 5005 mixture is frequency-controlled phase modulation, as in a dual frequency liquid crystal, while dielectric anisotropy goes to zero instead of being negative at high frequencies. For each component of the mixture, details on mesomorphic properties and their role in the formulation of the mixture are reported. The 5005 mixture was characterized by multiple investigation techniques, such as temperature dependence dielectric anisotropy, transmittance measurements image polarizing microscopy, and UV stability.

Highlights

Liquid crystal’s (LC) optical properties are electrically tunable, and they are attractive for displays [1,2,3,4,5,6,7,8], spatial light modulators [9,10,11], laser beam steering [11,12,13], lenses [14,15,16], filters [17,18], etc
We have demonstrated that astigmatism and aberration can be minimized in LC micro-lenses with tunable focal length determined by frequency, keeping driving voltage constant [14]
The optical characteristics of the frequency-controlled birefringence effect were observed in dual-frequency liquid crystals (DFLCs)

Summary

Introduction

Liquid crystal’s (LC) optical properties are electrically tunable, and they are attractive for displays [1,2,3,4,5,6,7,8], spatial light modulators [9,10,11], laser beam steering [11,12,13], lenses [14,15,16], filters [17,18], etc. We study a high birefringence NLC material with ∆n = 0.32 and high dielectric anisotropy ∆ε, which is positive in the working frequency range This mixture (named 5005) was formulated in the Institute of Chemistry at Military University of Technology in Warsaw, and it can be controlled to DFLC, but its frequencies are low, and the sign of dielectric anisotropy does not change. Using this mixture, multiple levels of phase modulation, tunable by adjusting the frequency of the applied signal from 3–34 kHz range, can be obtained [24]. We describe the influence of temperature on the dielectric properties, and UV stability tests have been performed

Physical Properties of LC Host

Findings

UV Stability Test