Patterning of Photonic Crystals Constructed by Light-driven Cholesteric Liquid Crystals

Photonic crystals fabricated by periodic dielectric materials generate a photonic bandgap to reflect the incident light, referred to structural color, which provides opportunities for various applications, including reflective displays, optical anti-counterfeiting, information storage, and VR/AR. The cutting edge in the development of the photonic crystals focuses on the dynamic tuning of the patterns with diverse structural colors. Cholesteric liquid crystals (CLCs) self-organize into helical superstructures induced by molecular chirality, and selectively reflect circularly polarized light with the same handedness as their helices according to Bragg’s law. Three key structural elements of the CLCs, including the pitch, handedness, and helical axis, are manipulated to construct different dimensional photonic crystals with tunable colors and specific handedness by designing chemical strictures of the photoresponsive chiral switches as well as employing numerous process technology. We remarkably widened the tuning range of reflection wavelength (＞ 2000 nm) by the piecewise phototuning strategy, realized continuous photopatterning according to programmable modulation of the CLC reflection, and created geminate labels carrying distinct information in reflective and fluorescent states with the aid of aggregation-induced emission materials. The projects were financially supported by the National Natural Science Foundation of China, and related works have been published in Nat. Commun., Adv. Mater., etc.

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