Field-induced polymer wall formation in a bistable smectic-A liquid crystal display

Abstract

We developed a composite system to produce robust bistable smectic-A ͑SmA͒ liquid crystal based flexible displays by encapsulating the liquid crystal material in a polymer wall structure. While keeping all the intrinsic bistable properties of the SmA material, the field-induced polymer walls bridge the two display substrates and bring significant advantages over the polymer dispersed liquid crystal structure. Here we analyze the performance of an encapsulated pixel and demonstrate superior electro-optical characteristics, high contrast ratio, and excellent sunlight readability.

Bistable SmA liquid‐crystal display driven by a two‐direction electric field

“…To prevent this phenomenon from occurring, the LC molecules try to tilt to hold the layer spacing, which in turn modulates the layer surface because the director of the LCs should be perpendicular to the layer surface in the SmA phase. 13,14 It easily forms parabolic focal-conic defects, 12 as shown in Fig. 3(e).…”

“…This device also displays a faster response time (less than 1 msec) from the bright to dark state than other bistable LC displays. [10][11][12] However, the driving voltage in our new mode is still too high for photonic application. In this paper, we provide a way to reduce the driving electric field of the bistable SmA LCD by adding high-dielectric-anisotropy ferroelectric nanoparticles into the host SmA material.…”

“…A conventional SmA LCD can achieve longtime bistability, but the display performance is poor due to operation in a scattering mode. [9][10][11][12] The director of the SmA LC is switched between a light transparent state (homeotropic orientation) and an opaque light scattering state (focal-conic texture) by applying an external field with various frequencies. Because of the strong electrohydrodynamic instability, during the application at low frequency (<1 kHz), the stable focal-conic texture forms in the bulk of the cell and scatters the incident light.…”

A multistable smectic‐A liquid‐crystal device with low threshold field

“…For most of nematic liquid-crystal (NLC) materials, the bistability can be induced by adding chiral dopant or changing the anchoring force exerted by the treatment of the alignment layers. [1][2][3] Otherwise, methods based on smectic-A (SmA) LCs are also attractive in that they exhibit good bistability and can be operated under a passive-matrix driving scheme, 4,5 letting them become the candidate for energy-saving and low-cost devices, such as flexible displays and switchable storage devices. There are two electrical addressing methods having been used in SmA LCDs.…”

Paperlike thermochromic display

“…For example, displays with high flexibility can be fabricated using liquid crystal encapsulated as single pixels in elastomer substrate, 3 or in field-induced polymer structures. 4 To drive the displays, conducting wires/patterns are indispensable for transmitting the controlling signals. Recently, an ultralow-power organic circuit has been realized.…”