Advanced liquid crystal-based switchable optical devices for light protection applications: principles and strategies

Abstract

With the development of optical technologies, transparent materials that provide protection from light have received considerable attention from scholars. As important channels for external light, windows play a vital role in the regulation of light in buildings, vehicles, and aircrafts. There is a need for windows with switchable optical properties to prevent or attenuate damage or interference to the human eye and light-sensitive instruments by inappropriate optical radiation. In this context, liquid crystals (LCs), owing to their rich responsiveness and unique optical properties, have been considered among the best candidates for advanced light protection materials. In this review, we provide an overview of advances in research on LC-based methods for protection against light. First, we introduce the characteristics of different light sources and their protection requirements. Second, we introduce several classes of light modulation principles based on liquid crystal materials and demonstrate the feasibility of using them for light protection. In addition, we discuss current light protection strategies based on liquid crystal materials for different applications. Finally, we discuss the problems and shortcomings of current strategies. We propose several suggestions for the development of liquid crystal materials in the field of light protection.

Tunable Liquid Lenses: Emerging Technologies and Future Perspectives

“…Liquid crystal lens based on liquid crystal material is also a kind of very important liquid lens, [ 168–171 ] and they can be applied in many fields, such as optical switch, AR/VR displays, and 3D displays. [ 172–174 ] As it is very different from liquid lens, this paper does not introduce it.…”

Recent advances in solar infrared light regulating smart windows based on organic materials

“…Again, this review focuses on systems with the active materials being organics, generally avoiding papers in which the active elements are primarily inorganic, differentiating this work from other reviews on NIR control elements. [13][14][15][16][17][18][19][20] Organics provide several potential advantages over using inorganic materials, including organics do not interfere with, among others, radio signals, GPS, or cell phones, [21] nor do they corrode. In addition, processing of organic materials often requires lower temperatures and simpler processes than inorganic materials.…”

“…As this is a follow‐up work, only research published since 2017 will be discussed. Again, this review focuses on systems with the active materials being organics, generally avoiding papers in which the active elements are primarily inorganic, differentiating this work from other reviews on NIR control elements [13–20] . Organics provide several potential advantages over using inorganic materials, including organics do not interfere with, among others, radio signals, GPS, or cell phones, [21] nor do they corrode.…”

Low-Voltage Haze Tuning with Cellulose-Network Liquid Crystal Gels

“…Subsequently, the integration of anisotropic fluids such as liquid crystals (LCs) into networks of amorphous polymers forms composites whose properties can be modulated by using electrical stimulation. Until now, electrically driven dynamic optical scattering from the polymer–liquid crystal (P-LC) composite materials has been the most successful approach for regulating optical transparency with reduced optical scattering losses in the visible and NIR wavelengths. ,− The fast rotation of the LC director (average orientation of rod-like LC molecules) with respect to the applied electric field in different types of LC-based composites including polymer-dispersed liquid crystals (PDLCs), , polymer-stabilized liquid crystals (PSLCs), − polymer-stabilized cholesteric textures (PSCTs), and nematic gels with aligned network of fibers , offers a fast and consistent optical response, which is necessary for practical applications. The robust and reliable modulation of optical transparency in P-LC composite materials has shown potential impacts in diverse optical technologies ranging from smart windows ,, and information displays − to vision therapy, , optical security devices, and many more. , Yet, electrical switching in P-LC composites, including the commercially available PDLCs, suffers from the requirement of a high driving voltage, which is a key limiting factor for smart glass applications, especially in terms of power efficiency and both costs and safety considerations associated with high-voltage wiring of window units.…”