Electric-field-induced orientation of polar organic microcrystals with different crystal sizes dispersed in liquid as a novel optical devices

DAST microcrystals with different crystal sizes, 250 nm to 600 nm, were prepared successfully by adding a special polymer in the inverse reprepicitation method. The relative changes in absorbance between applied and unapplied electric field were found to be approximately proportional to the crystal sizes. The applied electric field was ca. 300 V/ cm and remarkably low, compared with ordinary liquid crystal systems. This result reflects that DAST microcrystal has huge dipole moment, which depended on crystal size, and the dispersion system is regarded as a new concept of "Liquid-and-Crystal".