Circularly polarized light emission from a chiral nematic phenylterthiophene dimer exhibiting ambipolar carrier transport

Abstract

A dimer bearing two phenylterthiophene parts linked by a chiral moiety with a minimized molecular volume has been synthesized. This chiral dimer exhibits a chiral nematic phase and its helical structure can be fixed by cooling rapidly. The helical pitch is shorter than the visible light wavelength and the reflection band can be tuned between near ultraviolet and infrared wavelengths by mixing enantiomers of the dimer or changing the temperature. The hole and electron mobilities in the chiral nematic phase are of the order of 10⁻⁵ cm² V⁻¹ s⁻¹. Circularly polarized light emission has been observed in the chiral nematic phase. In the fluidic chiral nematic phase, circularly polarized photoluminescence can be switched to a non-polarized state reversibly by the application of the electric field.