Liquid crystals bearing extended π-conjugated units function as organic semiconductors and liquid crystalline semiconductors have been studied for their applications in light-emitting diodes, field-effect transistors, and solar cells. However, studies on electronic functionalities in chiral liquid crystal phases have been limited so far. Electronic charge carrier transport has been confirmed in chiral nematic and chiral smectic C phases. In the chiral nematic phase, consisting of molecules bearing extended π-conjugated units, circularly polarized photoluminescence has been observed within the wavelength range of reflection band. Recently, circularly polarized electroluminescence has been confirmed from devices based on active layers of chiral conjugated polymers with twisted structures induced by the molecular chirality. The chiral smectic C phase of oligothiophene derivatives is ferroelectric and indicates a bulk photovoltaic effect, which is driven by spontaneous polarization. This bulk photovoltaic effect has also been observed in achiral polar liquid crystal phases in which extended π-conjugated units are properly assembled. In this manuscript, optical and electronic functions of these chiral π-conjugated liquid crystalline semiconductors are reviewed.

中文翻译：

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手性液晶电子系统

具有扩展的π共轭单元的液晶用作有机半导体，并且已经研究了液晶半导体在发光二极管，场效应晶体管和太阳能电池中的应用。但是，迄今为止，对手性液晶相中的电子功能的研究受到限制。已经在手性向列相和手性近晶C相中证实了电荷载流子的传输。在由带有扩展的π共轭单元的分子组成的手性向列相中，在反射带的波长范围内观察到圆偏振光致发光。近来，已经从基于手性共轭聚合物的活性层的器件证实了圆偏振电致发光，所述手性共轭聚合物具有由分子手性引起的扭曲结构。寡聚噻吩衍生物的手性近晶C相是铁电的，并表明整体光伏效应，这是由自发极化驱动的。在非手性极性液晶相中还观察到了这种整体光伏效应，其中扩展的π共轭单元被适当地组装。在本手稿中，对这些手性π共轭液晶半导体的光学和电子功能进行了综述。