Dynamic orientation of oligothiophenes in nematic liquid crystalline matrices

Polarized photoluminescence is observed from conjugated oligomers dissolved in nematic liquid crystalline matrices. In this host-guest system, conjugated oligomers (guest) exhibit an emission spectrum well separated from the emission of the liquid crystalline matrix (host). Therefore, the polarization of the photoluminescence spectrum in these systems is a well-defined measure of the orientation of the guest molecules (oligothiophenes) within the host matrix. The results clearly demonstrate the spontaneous orientation of the oligothiophenes along the director of the nematic matrix. Furthermore, upon applying an electric field perpendicular to the direction of the spontaneous orientation, the oligomers are dynamically reoriented (switched) with the host. This results in switching of the polarized photoluminescence. Keywords: Oligothiophene; Dynamic orientation; Crystals; Nematic matrices