Evaluation of orientation and ordering of liquid crystalline triphenylene derivatives in microspace

Abstract We have investigated the molecular orientation of a columnar liquid crystalline triphenylene derivative hexapentyloxytriphenylene (H5T) at the interface of micro pillar walls. Samples were fabricated with sandwich structure cells and the pillars were formed by patterning photoresist with a minimum pitch of 5 μm. In conventional nematic liquid crystalline materials, polarized optical microscope (POM) images showed that the molecular orientation in nematic phase was observed to be affected in the region of approximately 10 μm near the pillars. On the other hand, the POM observation of H5T film could not reveal the disorder of molecular orientation near the pillars in this study. X-ray diffraction, Raman mapping, and time-of-flight measurements suggested that molecular orientation was disordered approximately 1–2 μm near the pillars. The small disordered region of H5T suggests that highly ordered columnar liquid crystalline materials are suitable for the miniaturization of organic semiconductor devices.