Investigation of Dynamic Orientation Process of Nematic Liquid Crystals Triggered by Conformational Change of Surface Monolayer

Yutaka MAJIMA  Keisuke KATO  Mitsumasa IWAMOTO  Kunihiro ICHIMURA  

IEICE TRANSACTIONS on Electronics   Vol.E81-C   No.7   pp.1070-1076
Publication Date: 1998/07/25
Online ISSN: 
Print ISSN: 0916-8516
Type of Manuscript: Special Section PAPER (Special Issue on Organic Materials for Optics and Electronics)
liquid crystal,  Langmuir-Blodgett film,  command surface,  transmittance,  capacitance,  

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We developed a measuring system that measures both capacitance and transmittance of a liquid crystal (LC) cell simultaneously. We then studied the dynamic orientation process of nematic LC molecules between two-photochromic command surfaces. The command surfaces consist of a polymer monolayer bearing azobenzene side chains and they are deposited on glass substrate coated with indium-tin-oxide by using the Langmuir-Blodgett technique. The capacitance of LC cells increased and decreased alternately due to orientation transition in LC molecules by irradiating ultraviolet (UV) and visible light, respectively. Similarly, with the alternating irradiation of UV and visible lights, the transmittance of the LC cell changed periodically. Mean tilt angles of LC molecules under irradiation of UV and visible lights were evaluated from the results of capacitance and transmittance. It was found that the transient transmittance response was delayed to the transient capacitance under the UV irradiation. This result corresponds to that the LC molecules in homeotropic mode tend to remain the optical alignment.