Photo-switchable chiral liquid crystal with optical tristability enabled by a photoresponsive azo-chiral dopant.

Yu-Cheng Hsiao,Kuan-Chung Huang,Wei Lee

doi:10.1364/oe.25.002687

Abstract

A light-driven tristable chiral-tilted homeotropic nematic (TCHN) cell is demonstrated. The liquid-crystal cell is photo-switchable among the three stable states: the tilted-homeotropic, fingerprint, and the tilted-twist states. The inclusion of a photosensitive chiral bis(azobenzene) compound into a typical nematic liquid crystal makes the resulting material possible to switch from one to another stable state directly and reversibly owing to the photoinduced trans-cis isomerization of the azo-chiral dopant and, hence, the configurational change of the liquid crystal via the guest-host effect. By further introducing dichroic dyes into the TCHN system, we devised a polarizer-free display and light modulators. The novel TCHN composite material opens up new possible applications in light-driven optical elements and devices.

Highlights

With the concept of green energy rising rapidly, energy-saving materials have attracted much global attention in recent years
The novel TCHN composite material opens up new possible applications in lightdriven optical elements and devices
Funding Ministry of Science and Technology (MOST), Taiwan, (104-2112-M-009-008-MY3)

Summary

Introduction

With the concept of green energy rising rapidly, energy-saving materials have attracted much global attention in recent years. White and Taylor suggested that a system of dye-doped, twisted-nematic LC device can absorb light polarized along all axes [15] Recently, Lee et al have devised a polarizer-free display based on a dye-doped bistable chiral-tilted homeotropic nematic (BHN) system [16]. A BHN system possesses two stable states; namely, the tilted-homeotropic (tH) and the tilted-twist (tT) states, operating in the crossed-polarizer scheme as the dark and bright states, respectively [1,2,17] It comprises a dual-frequency LC (DFLC) doped with a chiral agent, enabling its switch between the bistable tH and tT states [17,18].

Experiment

Results and discussion

Conclusions