Flexoelectric-effect-based light waveguide liquid crystal display for transparent display

Abstract

We report a light waveguide liquid crystal display (LCD) based on the flexoelectric effect. The display consists of two parallel flat substrates with a layer of flexoelectric liquid crystal sandwiched between them. A light-emitting diode (LED) is installed on the edge of the display and the produced light is coupled into the display. When no voltage is applied, the liquid crystal is uniformly aligned and is transparent. The incident light propagates through the display by total internal reflection at the interface between the substrate and air, and no light comes out of the viewing side of the display. The display appears transparent. When a voltage is applied, the liquid crystal is switched to a micrometer-sized polydomain state due to flexoelectric interaction and becomes scattering. The incident light is deflected from the waveguide mode and comes out of the viewing side of the display. We achieved thin-film-transistor active matrix compatible driving voltage by doping liquid crystal dimers with large flexoelectric coefficients. The light waveguide LCD does not use polarizers as in conventional LCDs. It has an ultrahigh transmittance near 90% in the voltage-off state. It is very suitable for transparent display, which can be used for head-up display and augmented reality display.

An Extended Reality System for Situation Awareness in Flood Management and Media Production Planning

“…In particular, Shin et al [1] proposed a light waveguide LCD based on the flexoelectric effect, achieving ultrahigh transmittance and a high contrast ratio for transparent displays. Another study [2] presented a new optical system for VR displays, achieving compactness, light weight, and high light efficiency.…”

Performances of Polymer-Dispersed Liquid Crystal Films for Smart Glass Applications

“…The transparency of the smart glass can be controlled either manually by human interaction or autonomously by detecting the environmental temperature [ 20 ]. Liquid crystals can also be found in transparent displays, such as liquid crystal displays (LCD), due to the light-modulating properties of the crystals [ 21 ]. As voltage is applied to an LCD display, the liquid crystals within it change into the micrometer-sized polydomain state [ 21 ].…”

Manipulating the Switching of Liquid Crystals by Interfacial Nanotips Penetrating Polyimide Hybrid Alignment Layers

“…Alignment layers ensuring the initial orientation of liquid crystals (LCs) are one of the most essential components in LC devices. − So far, a lot of continuous works are focusing on aligning LCs. Dielectric polyimide (PI) is the most popular commercial alignment layer because of its high transparency, excellent thermal stability, long lifetime, and so on and has been proven to actualize the excellent electro-optical switching of LCs in liquid crystal displays (LCDs), lens, optical elements, terahertz devices, etc. − Recently, alignment layers with artificially micropatterned surface topologies have shown significant advantages in actualizing the flexibility of LC devices with the raised electro-optical performances. − However, the microscale architectures on alignment layers demand a more complicated fabrication process and generally are very expensive. These days, the hybrid thin layers prepared by blending nanoparticles in polymer solutions arise and are so attractive in altering the interfacial surface characteristics because of the simplified fabrication process, the obvious surface topology, and the generated surface interaction. − The carbon nanotubes (CNTs) in hybrid thin layer evidently accelerate the electro-optical switch of LCs, and the VO 2 nanoparticle-doped PI hybrid thin layer with remarkably roughened surface has been proven to efficiently prevent the sliding of LCs in a flexible cell .…”