Towards high charge-carrier mobilities by rational design of the shape and periphery of discotics
Towards high charge-carrier mobilities by rational design of the shape and periphery of discotics
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DOI：
10.1038/nmat2427
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发表时间：
2009-05-01
期刊：
影响因子：
41.2
通讯作者：
Muellen, Klaus
中科院分区：
文献类型：
--
作者：
Feng, Xinliang;Marcon, Valentina;Muellen, Klaus
盘状液晶具有自组织和电荷传输特性，是一类很有前途的分子电子学材料。到目前为止，最好的止痛药是围绕冠烯单元构建的，并具有六重对称性。在盘状阶段，六重对称的分子堆叠在一起，平均扭曲30度，而导致最大电子耦合的角度是60度。在这里，我们合成了一个具有三重对称性的亲水/疏水侧链交替的分子，并用X射线散射证明了所需螺旋结构的形成。时间分辨微波电导测量表明，该材料确实具有很高的迁移率，0：2 cm(2)V(-1)S(-1)。用分子动力学方法模拟了分子的组装过程，验证了X射线散射模型。模拟的结构，结合量子化学技术，证明了迁移率仍然受到结构缺陷的限制，并且无缺陷组装可以导致迁移率超过10 cm(2)V(-1)S(-1)。
Discotic liquid crystals are a promising class of materials for molecular electronics thanks to their self-organization and charge transporting properties. The best discotics so far are built around the coronene unit and possess six-fold symmetry. In the discotic phase six-fold-symmetric molecules stack with an average twist of 30 degrees, whereas the angle that would lead to the greatest electronic coupling is 60 degrees. Here, a molecule with three-fold symmetry and alternating hydrophilic/hydrophobic side chains is synthesized and X-ray scattering is used to prove the formation of the desired helical microstructure. Time-resolved microwave-conductivity measurements show that the material has indeed a very high mobility, 0 : 2 cm(2) V(-1)s(-1). The assemblies of molecules are simulated using molecular dynamics, confirming the model deduced from X-ray scattering. The simulated structures, together with quantum-chemical techniques, prove that mobility is still limited by structural defects and that a defect-free assembly could lead to mobilities in excess of 10 cm(2) V(-1)s(-1).