Polymer Stabilized Bistable Dual Frequency Cholesteric Liquid Crystal Devices Assisted by a Predesigned Chiral Dopant

2021 ◽  
Author(s):  
Chun-Yen Liu ◽  
Chi-Feng Yen ◽  
Yi-Hua Hung ◽  
Chia-Ming Tu ◽  
Guan-Yi Wu ◽  
...  
Keyword(s):  
Liquid Crystal ◽  
Liquid Crystals ◽  
Cholesteric Liquid Crystal ◽  
Photonic Devices ◽  
Smart Devices ◽  
Dual Frequency ◽  
External Stimulation ◽  
Liquid Crystal Devices ◽  
Polymer Stabilized

Liquid crystals have great potential for developing photonic devices that control the optical behaviors of liquid crystals in smart devices with external stimulation. In this study, we demonstrated a series...

Thermal and electrical wavelength tuning of Bragg reflection with ultraviolet light absorbers in polymer-stabilized cholesteric liquid crystals

2018 ◽  
Vol 6 (45) ◽  
pp. 12377-12385 ◽  
Author(s):  
Amid Ranjkesh ◽  
Tae-Hoon Yoon
Keyword(s):  
Liquid Crystal ◽  
Liquid Crystals ◽  
Electric Field ◽  
Ultraviolet Light ◽  
Bragg Reflection ◽  
Cholesteric Liquid Crystal ◽  
Wavelength Tuning ◽  
Cholesteric Liquid Crystals ◽  
Light Absorbers ◽  
Polymer Stabilized

A dual thermal and electrical polymer-stabilized cholesteric liquid crystal has been fabricated by using ultraviolet light absorbers. The Bragg reflection can be autonomously controlled by temperature and manually by an electric field.

scholarly journals Photo-Aligned Ferroelectric Liquid Crystal Devices with Novel Electro-Optic Characteristics

Crystals ◽  
2020 ◽  
Vol 10 (7) ◽  
pp. 563
Author(s):  
Vladimir Chigrinov ◽  
Qi Guo ◽  
Aleksey Kudreyko
Keyword(s):  
Liquid Crystal ◽  
Liquid Crystals ◽  
Berry Phase ◽  
Photonic Devices ◽  
Ferroelectric Liquid Crystal ◽  
Optical Elements ◽  
Ferroelectric Liquid Crystals ◽  
Liquid Crystal Devices ◽  
Alignment Technique ◽  
Photo Alignment

This paper examines different applications of ferroelectric liquid crystal devices based on photo-alignment. Successful application of the photo-alignment technique is considered to be a critical breakthrough. A variety of display and photonic devices with azo dye aligned ferroelectric liquid crystals is presented: smart glasses, liquid crystal Pancharatnam–Berry phase optical elements, 2D/3D switchable lenses, and laser therapy devices. Comparison of electro-optical behavior of ferroelectric liquid crystals is described considering the performance of devices. This paper facilitates the optimization of device design, and broadens the possible applications in the display and photonic area.

scholarly journals Enhanced Bandwidth Broadening of Infrared Reflector Based on Polymer Stabilized Cholesteric Liquid Crystals with Poly(N-vinylcarbazole) Used as Alignment Layer

Polymers ◽  
2021 ◽  
Vol 13 (14) ◽  
pp. 2238
Author(s):  
Limin Zhang ◽  
Qiumei Nie ◽  
Xiao-Fang Jiang ◽  
Wei Zhao ◽  
Xiaowen Hu ◽  
...  
Keyword(s):  
Liquid Crystal ◽  
Liquid Crystals ◽  
Electric Field ◽  
Cholesteric Liquid Crystal ◽  
Critical Role ◽  
Cholesteric Liquid Crystals ◽  
Smart Window ◽  
Alignment Layer ◽  
Thermal And Electrical Properties ◽  
Polymer Stabilized

Alignment layer plays a critical role on liquid crystal (LC) conformation for most LC devices. Normally, polyimide (PI) or polyvinyl alcohol (PVA), characterized by their outstanding thermal and electrical properties, have been widely applied as the alignment layer to align LC molecules. Here, we used a semi-conductive material poly(N-vinylcarbazole) (PVK) as the alignment layer to fabricate the cholesteric liquid crystal (CLC) device and the polymer-stabilized cholesteric liquid crystals (PSCLC)-based infrared (IR) reflectors. In the presence of ultraviolet (UV) irradiation, there are hole–electron pairs generated in the PVK layer, which neutralizes the impurity electrons in the LC–PVK junction, resulting in the reduction in the built-in electric field in the LC device. Therefore, the operational voltage of the CLC device switching from cholesteric texture to focal conic texture decreases from 45 V to 30 V. For the PSCLC-based IR reflectors with the PVK alignment layer, at the same applied electric field, the reflection bandwidth is enhanced from 647 to 821 nm, ranging from 685 to 1506 nm in the IR region, which makes it attractive for saving energy as a smart window.

scholarly journals Overlooked Ionic Phenomena Affecting the Electrical Conductivity of Liquid Crystals

2021 ◽  
Vol 11 (1) ◽  
pp. 1
Author(s):  
David Webb ◽  
Yuriy Garbovskiy
Keyword(s):  
Electrical Conductivity ◽  
Liquid Crystal ◽  
Liquid Crystals ◽  
Physical Properties ◽  
Soft Matter ◽  
Photonic Devices ◽  
Optical Components ◽  
Dynamically Reconfigurable ◽  
Liquid Crystal Devices ◽  
New Applications

Liquid crystal devices, such as displays, various tunable optical components, and sensors, are becoming increasingly ubiquitous. Basic physical properties of liquid crystal materials can be controlled by external physical fields, thus making liquid crystal devices dynamically reconfigurable. The tunability of liquid crystals offers exciting opportunities for the development of new applications, including advanced electronic and photonic devices, by merging the concepts of flat optics, tunable metasurfaces, nanoplasmonics, and soft matter biophotonics. As a rule, the tunability of liquid crystals is achieved by applying an electric field. This field reorients liquid crystals and changes their physical properties. Ions, typically present in liquid crystals in minute quantities, can alter the reorientation of liquid crystals through the well-known screening effect. Because the electrical conductivity of thermotropic liquid crystals is normally caused by ions, an understanding of ion generation processes in liquid crystals is of utmost importance to existing and emerging technologies relying on such materials. That is why measuring of electrical conductivity of liquid crystals is a standard part of their material characterization. Measuring the electrical conductivity of liquid crystals is a very delicate process. In this paper, we discuss overlooked ionic phenomena caused by interactions of ions with substrates of the liquid crystal cells. These interactions affect the measured values of the DC electrical conductivity of liquid crystals and make them dependent on the cell thickness.

scholarly journals Thermo-Chromic Response of Polymer Stabilized Cholesteric Liquid Crystal for Thermal Imaging

2019 ◽  
Vol 1 (2) ◽  
Author(s):  
Rishi Kumar
Keyword(s):  
Optical Properties ◽  
Liquid Crystal ◽  
Liquid Crystals ◽  
Thermal Imaging ◽  
Cholesteric Liquid Crystal ◽  
Helical Structure ◽  
Cholesteric Liquid Crystals ◽  
Polymer Stabilized

Cholesteric liquid crystal (Ch-LC) exhibits many remarkable optical properties due to formation of a macroscopic helical structure. A low amount of monomer (5wt.%) is dispersed into cholesteric liquid crystal and get polymerized under UV radiations to form polymer stabilized cholesteric texture (PSCT). The thermo-chromic response made this device suitable for the developing applications in thermal imaging. Temperature based measurements of PSCT exploits the key property of some polymer stabilized cholesteric liquid crystals (PSCLC) to reflect definite colors at specific temperatures. The selective color of PSCT texture shifts with raise in temperature from 30oC to 85oC, which can be utilized in thermal imaging applications.

scholarly journals Liquid Crystal Devices for Beam Steering Applications

Micromachines ◽  
2021 ◽  
Vol 12 (3) ◽  
pp. 247
Author(s):  
Rowan Morris ◽  
Cliff Jones ◽  
Mamatha Nagaraj
Keyword(s):  
Liquid Crystal ◽  
Liquid Crystals ◽  
Adaptive Optics ◽  
Beam Steering ◽  
Optical Components ◽  
Advantages And Disadvantages ◽  
Liquid Crystal Devices

Liquid crystals are valuable materials for applications in beam steering devices. In this paper, an overview of the use of liquid crystals in the field of adaptive optics specifically for beam steering and lensing devices is presented. The paper introduces the properties of liquid crystals that have made them useful in this field followed by a more detailed discussion of specific liquid crystal devices that act as switchable optical components of refractive and diffractive types. The relative advantages and disadvantages of the different devices and techniques are summarised.

Graphene Glass Inducing Multidomain Orientations in Cholesteric Liquid Crystal Devices toward Wide Viewing Angles

ACS Nano ◽  
2018 ◽  
Vol 12 (7) ◽  
pp. 6443-6451 ◽  
Author(s):  
Huihui Wang ◽  
Bingzhi Liu ◽  
Ling Wang ◽  
Xudong Chen ◽  
Zhaolong Chen ◽  
...  
Keyword(s):  
Liquid Crystal ◽  
Cholesteric Liquid Crystal ◽  
Liquid Crystal Devices ◽  
Graphene Glass
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