Temperature-independent hole mobility of a smectic liquid-crystalline semiconductor based on band-like conduction.
Temperature-independent hole mobility of a smectic liquid-crystalline semiconductor based on band-like conduction.
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DOI：
10.1002/cphc.201300362
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发表时间：
2013-08
期刊：
影响因子：
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通讯作者：
M. Funahashi;T. Ishii;A. Sonoda
中科院分区：
文献类型：
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作者：
M. Funahashi;T. Ishii;A. Sonoda
采用真空升华法制备了一种液晶(LC)苯基三噻吩衍生物，该化合物在室温下呈有序的近晶相。在升华过程中，真空管表面生长出尺寸为1 mm的薄片。这些晶体的X射线衍射图与通过使用有机溶剂的传统重结晶过程形成的LC状态的有序近晶相相同。由于化学杂质的去除，室温下真空生长的薄膜有序近晶相的空穴迁移率增加到1.20×10(-1)cm(-1)·V(-1)·S(-1)，而LC析出物的空穴迁移率为7×10(-2)cm(-2)·V(-1)·S(-1)。真空升华样品的有序近晶相中的空穴迁移率在400~220K之间与温度无关，在此温度范围内空穴迁移率的电场依赖性也很小。空穴迁移率与温度的关系可用Hoester ey-Letson模型很好地描述。空穴输运特性表明，受局域态影响的带状导电机制，而不是载流子跳跃机制，是有序近晶相中空穴输运的有效机制。
A liquid-crystalline (LC) phenylterthiophene derivative, which exhibited an ordered smectic phase at room temperature, was purified by vacuum sublimation under a flow of nitrogen. During the sublimation process, thin plates with sizes of 1 mm grew on the surface of the vacuum tube. The crystals exhibited the same X-ray diffraction patterns as the ordered smectic phase of the LC state that was formed through a conventional recrystallization process by using organic solvents. Because of the removal of chemical impurities, the hole mobility in the ordered smectic phase of the vacuum-grown thin plates increased to 1.2×10(-1) cm(2) V(-1) s(-1) at room temperature, whereas that of the LC precipitates was 7×10(-2) cm(2) V(-1) s(-1). The hole mobility in the ordered smectic phase of the vacuum-sublimated sample was temperature-independent between 400 and 220 K. The electric-field dependence of the hole mobility was also very small within this temperature range. The temperature dependence of hole mobility was well-described by the Hoesterey-Letson model. The hole-transport characteristics indicate that band-like conduction affected by the localized states, rather than a charge-carrier-hopping mechanism, is a valid mechanism for hole transport in an ordered smectic phase.