Supramolecular structure of columnar liquid crystalline π-conjugated oligothiophenes with highly polarized photoluminescence properties

It is possible to control the alignment of columnar liquid crystalline π-conjugated systems by controlling photoluminescence (PL) properties to yield a polarized PL effect by shear stress. A polarization ratio of 11.2 at the fluorescence peak was obtained using columnar liquid crystalline π-conjugated oligothiophenes [T. Yasuda, Adv. Funct. Mater. 19, 411 (2009)]. We have therefore revealed the directional distribution of oligothiophene molecules inside the columns, which is the origin of a highly polarized PL emission, through detailed analysis of the dependence of PL polarization ratio on the detection polar angle, assuming that such PL emission is due to the summation of all dipole radiations from oligothiophene molecules in the measured area of the sample.