Diastereomeric Effect on Bulk Photovoltaic Property and Polarized Electroluminescence in Ferroelectric Liquid Crystals Containing an Extended π-Conjugated Unit

Abstract

We synthesized two diastereomers comprising the same π-conjugated unit. One diastereomer exhibited a smectic crystal phase in which the chromophores tilted 45 degrees from the layer normal and macroscopic polarization was induced by a DC bias application in a cooling process from the high temperature phase to the smectic crystal phase. The other diastereomer exhibited a smectic crystal phase in which the chromophores were parallel to the layer normal and macroscopic polarization was not induced. The bulk photovoltaic effect and polarization-induced electroluminescence were observed only in the polarized smectic crystal phase in which the chromophores tilted from the layer normal. In the bulk photovoltaic effect in the tilted smectic crystal phase doped with fullerene derivative, the open circuit voltage and short circuit current were 1.03 V and 100 µAcm−2 for white light illumination (20 mWcm−2), respectively. In the polarization-induced electroluminescence in the tilted smectic crystal phase, linearly polarized emission with the dichroic ratio exceeding 10 was obtained and the axis of the linearly polarized emission could be rotated 90 degrees by an inversion of a DC bias of poling treatment.

Exploring the Impact of Linkage Structure in Ferroelectric Nematic and Smectic Liquid Crystals

“…reported an unidentified N phase of RM734, whose ferroelectric features were later confirmed . Furthermore, an LC molecule showing an N F phase at ambient temperature was recently described by Manabe et al Although ferroelectric LC materials have been extensively studied recently, − the origin of ferroelectricity, including the propagation of the microscopic orientation of molecular dipole moments to macroscopic spontaneous polarization, remains poorly understood.…”