The growing need for cheap, reliable, economical, and environmentally safe sources of energy has prompted extensive research into the field of organic photovoltaics. Oligo(p-phenylenevinylenes) (OPVs) are model compounds for the polymer poly (p-phenylenevinylenes). These compounds are a highly conjugated, hole conductive materials used in both organic photovoltaics and organic light emitting diodes. Unfortunately, little research exists concerning the effects of nano- and microstructure on organic photovoltaic performance. In other words, how does the spatial relationship between adjacent OPV chains influence photoconductivity? The first project of this dissertation was comprised of two parts. The first part dealt with the need to improve the asymmetric synthesis of OPV chains. By modifying the current literature approach towards asymmetric OPVs, the total overall yield of these chromophores has been optimized to values that are 15 – 30% higher than current literature values. The methodology and synthetic steps are explored. This project became the basis for the second part, which was the synthesis of two OPV units attached cofacially to bridging groups, in order to study energy and electronic transfer between the two units as a function of interchain distance, angle, and/or orbital overlap.
The second project of this dissertation dealt with the creation of liquid crystalline perylene diimide (PDI) aggregates through non-covalent interactions. Perylene diimides have been utilized as optimal n-type materials for photoconductive organic devices, and have strong intermolecular π-π interactions that induce specific packing orientations. The nature of the packing can be influenced by the substituent at the cyclic imide portion of the chromophore. This unit has no real effect on the ground state electronic properties of the individual chromophore because it is located at a node in the PDI interacting molecular orbitals. The PDI therefore behaves as an isolated chromophore with minimal to no ground state mixing with the imide substituent. Nevertheless, the structure of that substituent can greatly influence the bulk properties of the chromophore by directly affecting the transverse and longitudinal packing in the solid state. The utilization of a hydrazide linkage could direct the self-assembly of appropriately substituted PDIs through both hydrogen bonding and π-π stacking, into ordered arrays. The synthesis and photophysical properties of these hydrazide-linked PDIs are presented.
The third and final project in this dissertation involves the self-assembly of a multichromophoric perylene diimide. Various self-assembly techniques were used to construct this assembly, including hydrogen bonding, π-π stacking, and ligation of metal-complexes, all of which provide site-specific platforms for the organized assembly of a multi-chromophoric system. The synthesis of this compound is presented.