Generation of pretilt angles on polyimides with a single linearly polarized UV exposure

We designed polyimide (PI) films containing fluorine atoms for liquid cryst al (LC) alignment using linearly polarized UV exposure. Using a single obli que polarized UV exposure we obtained unidirectional LC alignment with any desired pretilt angles from 0 degrees up to 90 degrees Pretilt angles depen d on the concentration of fluorine atoms in PI and the UV exposure time and angle. Dichroic ratio and capacitance measurements of the LC cells suggest that oblique polarized UV exposure breaks the surface order degeneracy of the LC molecules, generating uniform pretilt angle along the optic axis of PI film.