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dc.contributor.authorNosheen, Shabeena
dc.date.accessioned2019-02-15T10:56:18Z
dc.date.available2019-02-15T10:56:18Z
dc.date.issued2019-03-30
dc.date.submitted2018-09-05
dc.identifier.urihttps://www.repository.cam.ac.uk/handle/1810/289439
dc.description.abstractSoft matter, self-assembled 3D photonic structures such as blue phase liquid crystals have of great interest to the displays industry and are highly desirable as spatial light modulators because of their polarisation independence and fast switching. However, these types of devices suffer from multistep fabrication conditions and require high threshold voltages. To overcome these limitations, two key points were considered: High flexoelectric liquid crystals are capable of uniform 3D self-assembly, with a wide temperature range but have high threshold voltages, whereas, other classes of high dielectric liquid crystals have fast electro-optic response times with low threshold voltages but show poor 3D self-assembly. In this work, new mixture formulations have been devised having both properties in moderation in order to achieve simple yet stable 3D self-assembled blue phases with fast response times at as low as possible applied fields. Dielectric materials were considered from a commercial source whereas, miscible flexoelectric soft materials were synthesised in-house. These synthesised materials were fully characterised. Then mixtures were formulated in commercial high dielectric hosts to study their miscibility, new mesogenic transitions and electro-optic responses in terms of flexoelectric and dielectric properties. The selected mixtures were further investigated for the rapid growth of blue phases and their compatibility with reactive mesogens to form stable blue phases at room temperature. This new formulation of materials has given rise to mixtures and devices which are inherently easy to fabricate allowing the robust and resilient growth of blue phases under an hour in standard laboratory conditions. Furthermore, polarisation independent electro-optic switching has been characterised at fields <1V micron m-1. For phase modulation studies of these stabilised blue phase devices, phase shift was measured using a modified Young’s slit interferometer. The observed results were very promising, with a full 2.5 pi phase shift observed at a field of 9.25 V micron m-1 when compared to earlier reported devices (which required complicated multistep fabrication processes) giving values of full 1.8 pi phase shifts at 20 V micron m-1.
dc.description.sponsorshipEPRSC, Merck KGaA
dc.language.isoen
dc.rightsAll rights reserved
dc.rightsAll Rights Reserveden
dc.rights.urihttps://www.rioxx.net/licenses/all-rights-reserved/en
dc.subjectLiquid Crystals
dc.subjectFlexoelectro-optic properties
dc.subjectBlue Phase
dc.subjectPhase modulation
dc.subjectYoung's Slit
dc.titleFlexo electro-optic Liquid Crystals for Phase Modulation
dc.typeThesis
dc.type.qualificationlevelDoctoral
dc.type.qualificationnameDoctor of Philosophy (PhD)
dc.publisher.institutionUniversity of Cambridge
dc.publisher.departmentDepartment of Engineering
dc.date.updated2019-02-06T16:22:07Z
dc.identifier.doi10.17863/CAM.36688
dc.publisher.collegeJesus College Cambridge
dc.type.qualificationtitlePhD in Engineering
cam.supervisorWilkinson, Timothy
cam.thesis.fundingtrue


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