Surface and Thin Film Chemistry of Functionalized Naphthalene and Perylene Tetracarboxylic Diimides

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Authors

Hewage, Awanthi P. K.

Issue Date

2014

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Dissertation

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Liquid Crystals , Silver nanoclusters , Surface Chemistry , Thin Film Chemistry

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Organic semiconductors have become part of a number of applications in various electronic and opto-electronic devices and this has continued to spark interest in the field of semiconductor research. Out of the many organic molecules that have been examined for potential use in semiconductor research, perylene and naphthalene core molecules have been targets of particular interest based on their thermal and photo stability. This dissertation explores the synthesis and investigation of several perylene and naphthalene core molecules that are potentially useful as precursors for organic semiconductors. The main focus of this research is to investigate the packing and order of these molecules in the subsequently synthesized films in the solid phase as well as in the liquid phase. Commercially available 3,4,9,10-perylene tetracarboxylic dianhydride and 1,4,5,8-naphthalene tetracarboxylic dianhydride were used to synthesize bis-(N,N-diethylaminoethyl)perylene 3,4,9,10-tetracarboxylic diimide and bis-(N,N-diethylaminoethyl)naphthalene-1,4,5,8-tetracarboxylic diimide molecules. The aqueous solubility of these diimides was increased by acidifying them using HCl and the resulting salts were dissolved in water to form solutions of varying concentration. The different solutions were coated onto glass substrates by a rod shear coating method and polarized ultraviolet-visible spectroscopy was used to characterize the relative order of the molecules in these films. These diimides were also dissolved in aqueous solutions containing different surfactants and these solutions were used to form both thin solid films and free standing liquid films. The relative order of the molecules in these surfactant-containing films was investigated using polarized ultraviolet-visible spectroscopy. Several other naphthalene core molecules similar to the diimides described above were functionalized with alternate terminal groups. These molecules were used to functionalize Ag surfaces and synthesize monolayer protected Ag clusters. Two different reducing agents were used to synthesize the Ag clusters from aqueous solutions of silver nitrate. Terminal thiol and carboxylic acid naphthalene core diimides were added to the reaction mixture resulting in the formation of capped nanoclusters. These were analyzed using ultraviolet-visible and fluorescence spectroscopies.In addition theoretical calculations were performed to study the surface interactions and reactions of 1,3,5,7-tetraazaadamantane and 1,3,5-triaza-7-phosphaadamantane molecules on the Si(100)-(2x1) surface. The specific aim was to compare the N atom binding on the Si surface vs the P atom binding on the Si surface. The calculations predict that binding through the phosphorous is slightly favored over bonding via the nitrogen atom. Attempts to confirm these results experimentally were inconclusive pending further modifications of the chamber doser.

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