Title: Programmable Coloration and Patterning on Reconfigurable Chiral Photonic Paper

Author: Shuzhen Cui, Lang Qin, Xiaojun Liu, Yanlei Yu*

Journal: Adv. Optical Mater., 2022, 10(5), 2102108

Abstract:

Responsive photonic crystals are widely employed to construct rewritable paper, where patterns are written and erased repeatedly via color switching. The working principle mainly lies in the changes on the lattice constant of periodic structures, which, however, restricts the localized color tuning of the recorded patterns and thus limits multicolor information transfer. Herein, a novel strategy is reported to write, erase, and importantly to tune the colors by developing unique light-driven cholesteric liquid crystals (CLCs) that possess self-organized helical superstructures with two structural elements of pitch lengths (lattice constant) and helical axes (reconfiguration). Recon-figuration of the helical axes provides two high-contrast optical states for writing and erasing by pressure and electricity, whereas precise photocontrol of the pitch lengths contributes to localized color tuning. These features primarily capitalize on the light-driven CLC with diverse photostationary colors, which is induced by a newly designed binary chiral system and confined in the polymer dispersed liquid crystal layer. Distinct multicolor patterns are mechanically written, optically tuned, and electrically erased on the rewritable photonic paper in a programmable manner. Such photonic paper has potential to record, program, and remember optically addressed images in visualized color information and user-interactive display technologies.

Fulltext Link: https://onlinelibrary.wiley.com/doi/full/10.1002/adom.202102108

In those photonic paper reported, the working principle behind the process of writing and erasing mainly lies in the changes on the only lattice constant of periodic structures which, however, restricts localized color tuning of the recorded patterns. To address the challenge, we introduce polymers into the light-driven cholesteric liquid crystals (CLCs) to fabricate the polymer dispersed liquid crystal (PDLC) via photopolymerization-induced phase separation, constructing the photonic paper which can write, erase and tune the structural colors by pressure, electricity and light, respectively. Such functions are primarily ascribed to the internal PDLC layer composed of the light-driven CLCs and polymer networks. The helical axes turn from focal conic (FC) state to planar state upon pressure and perform the writing process; taking advantage of phototunable pitch length, the paper show colorful patterns; exposed to electricity, the helical axes refigure to FC state and erase the pattern. Furthermore, one should be emphasized that the basic “write-erase” cycles of normal photonic paper are upgraded to novel “write-tune-erase” and “tune-write-erase” modes. We demonstrate the potential of our photonic paper to record, program, and remember intricate multicolor information in user-interactive display technology.