Nature 361, 428 - 430 (04 February 1993); doi:10.1038/361428a0

Photochemical switching of polarization in ferroelectric liquid-crystal films

Tomiki Ikeda^*, Takeo Sasaki & Kunihiro Ichimura

PRESTO, JRDC, Research Laboratory of Resources Utilization, Tokyo Institute of Technology, 4259 Nagatsuta, Midori-ku, Yokohama 227, Japan
^* To whom correspondence should be addressed.

LIQUID crystals have been used extensively as active media in display devices such as full-colour television screens. These devices are generally based on changes in the arrangement of the liquidcrystal molecules induced by electric fields, which change their optical properties¹. Ferroelectric liquid crystals^2,3 exhibit spontaneous polarization and therefore show a faster response to changes in the applied field. Switching of this field causes a reversal in the direction of polarization^2–;5. Here we report polarization switching in ferroelectric liquid crystals driven by a photochemical process. The liquid-crystal films are doped with a photochromic compound which undergoes trans–cis isomerization on irradiation. Photoisomerization induces a change in the switching potential of the host liquid-crystal film, and thereby causes switching at the irradiated sites. The process is fast, stable, reversible and repeatable, and should be exploitable in device applications.

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