Max Planck Institute for Polymer Research , Ackermannweg 10, 55128 Mainz, Germany.
Department of Molecular Physics, Faculty of Chemistry, Lodz University of Technology , Zeromskiego 116, 90-924 Lodz, Poland.
ACS Appl Mater Interfaces. 2016 Jun 29;8(25):16200-6. doi: 10.1021/acsami.6b03233. Epub 2016 Jun 17.
The effect of dielectric roughness on the microstructure evolution of thermally evaporated α,ω-dihexylsexithiophene (α,ω-DH6T) thin films from a single molecular layer to tens of monolayers (ML) is studied. Thereby, the surface roughness of dielectrics is controlled within a sub-nanometer range. It is found that the grain size of an α,ω-DH6T ML is affected by dielectric roughness, especially for 1.5 ML, whereby the transistor performance is barely influenced. This can be attributed to a domain interconnection in the second layer over a long-range formed on the rough surface. With deposition of more layers, both microstructure and charge carrier transport exhibit a roughness-independent behavior. The structural characterization of α,ω-DH6T 10 ML by grazing-incidence wide-angle X-ray scattering reveals that the interlayer distance is slightly decreased from 3.30 to 3.15 nm due to a higher roughness, while an unchanged π-stacking distance is in excellent agreement with the roughness-independent hole mobility. This study excludes the influence of molecular-solvent interaction and preaggregation taking place during solution deposition, and provides further evidence that the microstructure of the interfacial layer of organic semiconductors has only minor impact on the bulk charge carrier transport in thicker films.
研究了介质粗糙度对从单分子层到数十个单层（ML）热蒸发的α，ω-二己基噻吩（α，ω-DH6T）薄膜微观结构演变的影响。从而，将电介质的表面粗糙度控制在亚纳米范围内。研究发现，α，ω-DH6T ML 的晶粒尺寸受介电粗糙度的影响，特别是在 1.5 ML 时，晶体管性能几乎不受影响。这可以归因于在粗糙表面上形成的第二层中的长程域连接。随着沉积更多的层，微观结构和电荷载流子输运都表现出与粗糙度无关的行为。掠入射广角 X 射线散射对α，ω-DH6T 10 ML 的结构表征表明，由于较高的粗糙度，层间距离略有从 3.30nm 减小到 3.15nm，而不变的π-堆积距离与粗糙度无关的空穴迁移率非常吻合。这项研究排除了在溶液沉积过程中发生的分子-溶剂相互作用和预聚集的影响，并进一步证明了有机半导体界面层的微观结构对较厚薄膜中体电荷载流子输运的影响很小。
