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|Title:||Studies of Alignment of Copper Phthalocyanine Compounds on Au(111) and Sidewall Functionalization of Single-Walled Carbon Nanotubes with Scanning Tunneling Microscopy|
|Keywords:||alignment of copper phthalocyanine, compounds, sidewall functionalization, carbon nanotubes, scanning tunneling microscopy, molecular electronics|
|Abstract:||<p> This thesis consists of two projects: alignment of copper phthalocyanine compounds on Au(111) and sidewall functionalization of single-walled carbon nanotubes on graphite. Both of these projects are performed with scanning tunneling microscopy (STM), which is used to study the structure of modified surfaces that are of interest in molecular electronics.</p> <p> In the first project, copper phthalocyanine compounds are made into a thin film with different methods, such as solution deposition, self-assembly and Langmuir-Blodgett film deposition. Those films are important materials in photoelectric devices such as organic light emitting diodes (OLED's). Molecules in these films are aligned on the solid surface with face-on orientation or edge-on orientation. However, the films of molecules with face-on orientation are preferentially used in LED's. In this project, we focus on finding a method to force molecules with face-on orientation in the film. The structure of copper octakisalkylthiophthalocyanine films on Au(111) was investigated with STM under ambient conditions. Columns of molecules are commonly observed due to the π-π interaction between molecules. The presence and length of alkyl chains in the molecules affects the alignment of molecules on the gold surface. The weak interaction between molecules and substrate caused the structure to be easily modified by an STM tip.</p> <p> In addition, chemical sidewall functionalization of SWCNTs was also explored with STM under ambient conditions. It was found that the spatial distribution of functional groups on nanotube sidewall is not random. Understanding the rules behind the distribution of functional groups will allow scientists to better control carbon nanotube functionalization and improve the properties of nanotubes. High resolution STM images provide direct evidence of the distribution and the effects of functional groups on nanotubes. Possible mechanisms are proposed to elucidate the process of SWCNT functionalization by free radicals and via the Bingel reaction.</p>|
|Appears in Collections:||Digitized Open Access Dissertations and Theses|
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