11 December 2002 Surface electrical potential of the aligning polymer substrates and dielectric properties of LC layers
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Proceedings Volume 4938, Selected Papers from the International Conference on Spectroscopy of Molecules and Crystals; (2002) https://doi.org/10.1117/12.486657
Event: XV International School on Spectroscopy of Molecules and Crystals, 2001, Chernivsti, Ukraine
Abstract
UV light influence on the surface potential φs of poly(vinylcinnamate) (PVCN) layers widely used for liquid crystal (LC) photoalignment is investigated. In case when PVCN film is spin coated on the ITO electrodes the surface potential changes under irradiation in both PVCN aligning film and ITO coating. The measured increment of the surface potential changes under irradiation in both PVCN aligning film and ITO coating. The measured increment of the surface potential Δφs=400 mV is mainly cuased by the photoconductivity of ITO electrodes, whereas the part caused by PVCN substrate is at least one order of magnitude lower. The relaxation time of Δφs for the ITO-PVCN coatings was estimated to be about 1 h. The induced potential may substantially modify dielectric properties of the aligned LC layers and its anchoring characteristics when the freshly irradiated substrates are used. On the contrary, this influence is weak when the substrates are irradiated several hours before the use for LC alignment.
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R. Kravchuk, Oleg V. Yaroshchuk, O. Kovalchuk, P. Karageorgiev, B. Stiller, Joachim Stumpe, "Surface electrical potential of the aligning polymer substrates and dielectric properties of LC layers", Proc. SPIE 4938, Selected Papers from the International Conference on Spectroscopy of Molecules and Crystals, (11 December 2002); doi: 10.1117/12.486657; https://doi.org/10.1117/12.486657
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