|10th November 2019|
( Nanowerk News ) A new technique for changing the structure of liquid crystals could lead to the development of fast-reacting liquid crystals suitable for next generation displays, e.g. For example, 3-D, augmented and virtual reality and advanced photonic applications such as mirrorless lasers, biosensors and fast / slow light generation, according to an international team of researchers from Penn State, the Air Force Research Laboratory and National Sun Yat-sen University, Taiwan ,
|"The liquid crystals we work with are called blue phase liquid crystals," said Iam Choon Khoo, a professor of electrical engineering at William E. Leonhard, the author of the article. "The most important thing about this research is the basic understanding of what happens when creating a field, which has led to the development of the technique of repetitive applied field. We believe that this method is almost a universal template with which many similar types of liquid crystals and soft matter can be reconfigured. "|
|Close-up of a mm-size blue-phase liquid crystal during its formation phase. (Photo: Khoo Lab / Penn State)|
|Liquid crystals of the blue phase typically self-assemble into a cubic photonic crystal structure. The researchers believed that by creating other structures, they could develop properties that are not present in their current form.|
After nearly two years of experimentation, they found that they could slowly move the crystals to stable and field-free orthorhombic and tetragonal structures by applying an intermittent electric field and relaxing the system between applications and dissipating the accumulated heat.
The resulting liquid crystals have a photonic bandgap that can be tuned to any location within the visible spectrum and has rapid responses required for a variety of next-generation displays and advanced photonic applications.
|The addition of a polymer to the crystal could stabilize it over a wide temperature range from freezing to near boiling, compared to its typical flawless counterparts, which are stable only in a range of 5 degrees. The polymer framework also speeds up the switching behavior.|
|In the latest research, the team uses the findings of this study ( Nature Materials "Reconfiguration of three-dimensional liquid crystalline photonic crystals by electrostriction") to generate new crystal structures and orientations using the electric field of a laser source.|
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