Modification of Naphthalene Core Tetracarboxylic Diimides for Silicon Surface Functionalizatioon

Abstract

Organic semiconductors have attracted increasing interest in the field of semiconductors, due to their possible potential applications in various electronic and opto-electronic devices. Perylene and naphthalene diimides are an important class of organic compounds which play a major role in the above mentioned areas. This dissertation describes the investigation of photophysical and photochemical properties of several naphthalene and perylene core molecules that are potentially useful as precursors for organic semiconductors. The main focus of the research was on functionalizing the cores to influence interactions with a substrate, and to further influence packing in the subsequent films and in the solid state. Using commercially available 3,4,9,10-perylene tetracarboxylic dianhydride and 1,4,5,8-naphthalene tetracarboxylic dianhydride, bis-(N,N-diethylaminoethyl)perylene-3,4,9,10-tetracarboxylic diimide and bis-(N,N-diethylaminoethyl)naphthalene-1,4,5,8-tetracarboxylic diimide were synthesized. The synthesized diimides were acidified with HCl in order to make them water soluble and were dissolved in water to form liquid crystalline solutions with different weight percents of diimide. The different solutions were coated onto glass or silica substrates by two different coating methods, rod shear coating and spin coating. The relative order of the molecules in these films was characterized by polarized ultraviolet-visible (UV-vis) and attenuated total reflectance Fourier transform infrared (IR) spectroscopies.Several other naphthalene core dye molecules were functionalized with a number of alternate terminal groups to allow for attachment to substrates of interest. These molecules were synthesized using traditional reflux methods as well as newly developed microwave synthesis methods. These molecules were characterized using UV-Vis, IR, and nuclear magnetic resonance techniques. In addition, theoretical calculations of these derivatives of naphthalene core dye molecules were examined to understand and compare the influence of the added terminal groups on the electronics of the core, and to aid in the characterization by comparing calculated properties to experimentally determined values. All the computational studies were performed by using Hartree-Fock or density functional theory (DFT) methods to examine the ground electronic states for these molecules. Excited state calculations were carried out using two methods available in the Gaussian03 program, either the configuration interaction with single excitation method and or time dependent DFT methods.