Fabrication of defect-free ferroelectric liquid crystal displays using photoalignment and their electrooptic performance

A photoalignment technique has been utilized for fabricatingzigzag-defect-f ree ferroelectric liquid crystal displays (FLCDs) using polyimide RN-1199, -1286, -1266 (Nissan Chem. Ind.) and adopting oblique irradiation of unpola rized UVlight. A rubbing technique was also utilized for comparison. It iss hown that among these polyimide materials, RN-1199 is the best forfabricati ng defect-free cells with C-1 uniform states, but RN-1286 requires low ener gy to produce a photoaligned FLC phase. We have conducted an analytical inv estigation to clarify the conditionsfor obtaining zigzag-defect-free C-1 st ates, and it is theoretically shown thatzigzag-defect-free C-1 state is obt ained using a low azimuthal anchoring energyat a low pretilt angle, while a zigzag-defect-free C-2 state is obtained byincreasing azimuthal anchoring energy above a critical value, also at alow pretilt angle. The estimated cr itical value of the azimuthalanchoring energy at which a transition from th e C-1 state to the C-2 state occurs is 3 x 10(-6)J/m(2) for the FLC materia l FELIX M4654/100 (Clariant) used in this research; this value is shown to fall in a favorable range which is measured in an independent experiment.