Ruiz Virginia, Nicholson Patrick G, Jollands Stuart, Thomas Pamela A, Macpherson Julie V, Unwin Patrick R
Department of Chemistry, University of Warwick, Coventry CV4 7AL, UK.
J Phys Chem B. 2005 Oct 20;109(41):19335-44. doi: 10.1021/jp053647k.
This paper reports the first comparison of the structure and electrical conductivity properties of spin cast (SC) and Langmuir-Schaeffer (LS) films of regioregular poly(3-hexylthiophene) (P3HT). In addition, the effect of incorporating highly monodisperse Au nanoparticles (NPs), with a core diameter of approximately 5 nm, into SC and LS P3HT films is described. A detailed picture of molecular organization in the films has been obtained using ultraviolet-visible absorption spectroscopy, atomic force microscopy, field-emission scanning electron microscopy, X-ray diffraction, and X-ray reflectivity. Film morphology was correlated with pseudo-two-dimensional conductivity measured using scanning electrochemical microscopy, with P3HT in the semiconducting regime. It was found that SC films, which were slightly thicker than those formed with the LS technique, exhibited greater organization. This resulted in an order of magnitude higher lateral conductivity for the SC films. Inclusion of Au NPs (50 wt %) into both SC and LS films resulted in the formation of uniform and relatively flat (rms roughness approximately 1 nm) composite films. Surprisingly, the addition of NPs did not disrupt the characteristic crystal structure found for the native P3HT films. The effect of Au NPs on film lateral conductivity was found to be determined by the distribution of Au NPs within the polymer, which varied significantly between SC and LS films. Whereas Au NPs aggregated into hexagonally packed clusters in SC films, NPs in LS films were predominantly uniformly distributed between the lamella bilayer. It was found that, while the inclusion of Au NPs caused the lateral conductivity to decrease in SC films, in LS films, the lateral conductivity increased by a factor of 2.
本文报道了对区域规整聚（3-己基噻吩）（P3HT）的旋涂（SC）薄膜和朗缪尔-谢弗（LS）薄膜的结构与电导率特性的首次比较。此外，还描述了将核心直径约为5 nm的高度单分散金纳米颗粒（NPs）掺入SC和LS P3HT薄膜中的效果。使用紫外-可见吸收光谱、原子力显微镜、场发射扫描电子显微镜、X射线衍射和X射线反射率获得了薄膜中分子排列的详细情况。薄膜形态与使用扫描电化学显微镜测量的准二维电导率相关，其中P3HT处于半导体状态。结果发现，比用LS技术形成的薄膜稍厚的SC薄膜表现出更高的有序性。这导致SC薄膜的横向电导率高出一个数量级。在SC和LS薄膜中都掺入Au NPs（50 wt%）导致形成均匀且相对平坦（均方根粗糙度约为1 nm）的复合薄膜。令人惊讶的是，添加NPs并未破坏天然P3HT薄膜的特征晶体结构。发现Au NPs对薄膜横向电导率的影响取决于Au NPs在聚合物中的分布，这在SC和LS薄膜之间有显著差异。在SC薄膜中，Au NPs聚集成六边形堆积的簇，而在LS薄膜中，NPs主要均匀分布在片层双分子层之间。结果发现，虽然掺入Au NPs会导致SC薄膜的横向电导率降低，但在LS薄膜中，横向电导率增加了2倍。
