Three Dimensional Self-Assembled Blue Phase Liquid Crystalline Photonic Crystal

Blue phase (BP) liquid crystals have been regarded as one kind of the most promising candidates for tunable three-dimensional photonic crystals due to their unique 3D self-assembly nanostructures, photonic bandgaps in visible light range and characteristics of soft matter. They exhibit great potential in numerous applications such as next-generation ultra-fast displays, reflection-mode displays, tunable lasers and optical communication devices. Herein, we provide the research advancement in the self-assembly structures of blue phase liquid crystals in recent years. First, the latest research on the hierarchical self-assembly of three-dimensional micro/nano structural and phase transition behaviors between three sub-phases are introduced. Then, the control methods of their self-assembly behavior or three-dimensional periodic lattice structures are demonstrated in detail. The lattice nucleation growth and lattice orientation of BPI and BPII can be modulated by substrate surface orientation treatment or nano patterning treatment. Owing to the response characteristics of BPs to external electric field, monodomain cubic crystals of BP or new sub-phase with non-cubic nanostructure can be obtained by controlling applied electric field. Besides, BP photonic crystals with different plane orientations can be obtained in a short time by appropriate heat treatment. These studies provide theoretical foundation for the appreciable application of BP materials in three-dimensional photonic crystals and functional devices. For example, the applications of blue phase liquid crystalline photonic crystal materials in optical fields such as tunable laser and tunable grating are shown. At the end of this review, the challenges and possible development direction of blue phase liquid crystalline photonic crystal is prospected briefly.