Materials and Surface Science Institute and Department of Chemical and Environmental Sciences, University of Limerick, Limerick, Ireland.
J Phys Chem B. 2013 Feb 14;117(6):1608-15. doi: 10.1021/jp305184n. Epub 2012 Nov 9.
Here we describe the formation of vertically aligned nanorod assemblies over several multilayers using CdS and CdSe nanorods by electrophoretic deposition. The presence of both charge and dipole on the rods allows both field driven deposition and orientational order to form close packed arrays where each rod is vertically aligned. Comparing assembly formation in electrophoresis to spontaneous assembly in solution gives important insights into nanorod organization by these different mechanisms. We show the influence of ligand environment on net charge (zeta potential) and its influence on assembly formation in CdSe nanorods that have long chain alkyl ligands (low charge) or pyridine ligands (high charge). The experimental observations show that highly charged rods deposit too quickly to allow close-packing to occur with perpendicular alignment only occurring with a lower net charge. This is supported by simulation predicting a lower energy configuration with a preference for perpendicular alignment as the charge state decreases. The resolute order that is retained over device scale areas and over several multilayers combined with inherent scalability of electrophoretic deposition makes this approach highly attractive for large scale nanorod integration in electronic, photonic, or photovoltaic devices.
在这里，我们通过电泳沉积的方法，描述了在多个多层结构上形成垂直排列的纳米棒组装体的过程。棒上的电荷和偶极子的存在使得电场驱动沉积和取向有序能够形成紧密堆积的阵列，其中每个棒都垂直排列。将电泳中的组装形成与溶液中的自发组装进行比较，可以深入了解不同机制对纳米棒组织的影响。我们展示了配体环境对净电荷（zeta 电位）的影响，以及它对具有长链烷基配体（低电荷）或吡啶配体（高电荷）的 CdSe 纳米棒组装形成的影响。实验观察表明，高电荷棒沉积太快，无法形成紧密堆积，只有在较低净电荷时才会发生垂直排列。这一结果得到了模拟的支持，模拟预测随着电荷状态的降低，具有垂直排列偏好的低能量构型更有可能出现。在器件尺度区域和多个多层结构上保留的这种有序性，以及电泳沉积固有的可扩展性，使得这种方法非常适合在电子、光子或光伏器件中进行大规模的纳米棒集成。
