Issue 11, 2011

Highly sensitive photoalignment of calamitic and discotic liquid crystals assisted by axis-selective triplet energy transfer

Abstract

Highly sensitive photoalignment of liquid crystals (LCs) can be realized by axis-selective triplet energy transfer. Addition of a triplet photosensitizer (phosphorescent donor) into a photocrosslinkable polymer tethering E-cinnamate side chains ensures dramatic enhancement of photosensitivity to generate the optical anisotropy of polymer film and surface-assisted LC photoalignment. Photoirradiation of triplet photosensitizer-doped polymer films with linearly polarized 365 nm light for the selective excitation of triplet sensitizer gives rise to optical anisotropy of cinnamates as a result of axis-selective triplet energy transfer. By analyzing phosphorescence spectra with theoretical Perrin's formula, we find that triplet energy transfer is efficient within a radius of ∼0.3 nm from the triplet photosensitizer. Such photoaligned polymer films can be used for the surface-assisted orientation photocontrol of not only calamitic LC, but also discotic LC, even for extremely low exposure energies. The present procedure would be greatly advantageous for high-throughput fabrication of optical devices by photoalignment techniques.

Graphical abstract: Highly sensitive photoalignment of calamitic and discotic liquid crystals assisted by axis-selective triplet energy transfer

Supplementary files

Article information

Article type
Paper
Submitted
04 Oct 2010
Accepted
07 Dec 2010
First published
10 Jan 2011

Phys. Chem. Chem. Phys., 2011,13, 4919-4927

Highly sensitive photoalignment of calamitic and discotic liquid crystals assisted by axis-selective triplet energy transfer

S. Furumi and K. Ichimura, Phys. Chem. Chem. Phys., 2011, 13, 4919 DOI: 10.1039/C0CP02016H

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