Molecular aspects of photoconversion processes in organic solar cells

The field of organic photovoltaics research has received a great deal of attention in the past years. Global climate changes are renewing the need for cleaner alternative energies that will prevent increased effects in global warming. Solar photoconversion arises as a natural option for the satisfaction of large energy demands with diminished impact on the environment. However, the high production costs of the current solar conversion technologies have prevented the widespread use of the sun as energy source. Costs reductions will be possible by the use of organic materials as photoactive materials since manufacturing processes are less demanding that those for the inorganic counterparts. However, current laboratory efficiencies do not match those required for commercialization and a huge leap into improved photoconversion must be achieved. Small molecule organic photovoltaics are a relatively new field and much is still to be known about the processes involved in solar-to-electric conversion. The introduction of new materials will provide the insight required for learning more about those processes. Organic synthesis will play a fundamental role in the evolution of this area.;It is the goal of this thesis to provide new insight into the processes that control the performance of small molecule organic photovoltaics. By introducing new materials systematically we can study, for example, the effects of the excited state nature or the extension of the pi system into the exciton diffusion length, or the molecular geometry in the resultant value of the open circuit voltage. A simple model for the description of the open circuit voltage will be presented that provides good evidence of the effects of molecular shape and geometry on the solar cell performance. Studies of the effects of charge collection at the organic/cathode interface will also be presented. The experimental procedures involved in the preparation and testing of the small molecule organic solar cells are presented and standard procedures for reporting efficiencies are highlighted. Finally, an additional relevant work on the photophysics of a newly synthesized cyclometallated platinum complex is presented.