Download ABSTRACT SYNTHESIS AND STUDY OF ELECTRO

ABSTRACT
SYNTHESIS AND STUDY OF ELECTRO-ACTIVE ORGANIC MOLECULES FOR
OPTOELECTRONIC APPLICATIONS
Shriya Hemalika Wadumethrige B.Sc. (Hons.)
Marquette University, 2012
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
-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(4alkyloxyphenyl)-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 alkoxysubstituted 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.