Date of Award
Doctor of Philosophy (PhD)
Gardinier, James R.
Electro-active organic materials have received considerable attention in the emerging area of molecular electronics and nanotechnology not only because of the attractive optical and electronic properties but also the advantages of organic materials such as low cost, easy processing, and great opportunities for structural modification. These materials are now being considered as active components in electronic and optoelectronic devices such as light emitting diodes for display applications, thin film transistors for low-cost and ultra-dense logic and memory circuits, photodiodes for optical information processing, and photovoltaic cells for solar energy harvesting. Therefore the electro-active organic materials have become a focus of intense research. This thesis concentrates the synthesis and study of optoelectronic properties of several classes of novel electro-active organic materials.
A series of electro-active tetraarylbenzo[1,2-b:4,5-b¡¦]difuran (BDF) and model diarylbenzofuran derivatives have been synthesized and their structures were established by X-ray crystallography. The single charge stabilization by benzodifuran and coplanar fÑ-aryl groups lying on the longitudinal suggests that the linear arrays of BDFs may allow the construction of molecular wires suitable for long-range electron transport. The synthesis of hexa alkyloxy substituted hexa-peri-hexabenzocoronene (HBC), a larger and eletron rich chromophore, via oxidative cyclodehydrogenation of hexakis(4-alkyloxyphenyl)-benzene produced a quantitative yield of an indenofluorene derivative rather than the expected HBC. The mechanistic considerations for the formation of the indenofluorene derivative led us to devise an alternative synthesis of elusive alkoxy-substituted HBC. Furthermore a series of alkyloxy substituted HBCs were prepared and their electronic properties were studied. A series of aryloxy-substituted tetraphenylethylenes (TPEs), tetraphenylethylene based dendrimers and a series of phenyl ethers were prepared and the effect of the diarylether linkage on their electronic and optical properties was studied. Although the diarylether linkage in TPEs did not affect the properties significantly, these linkages in poly-p-phenyl ethers seem to mediate the delocalization of the cationic charges. A series of cycloannulated aromatic donors were prepared for the preparation of stable cation radical salts. The availability of wide range of donors with varied redox potentials (0.82 V- 1.85 V) and spectroscopic features make these cation radicals to be valuable oxidants for variety of organic, inorganic and organometallic donors.