Synthesis and characterization of functional dyes for optoelectronic applications

Fossil fuels have been in the center of the global energy consumption for many years, contributing to serious complications in the environment and becoming gradually exhausted. Hence, seeking low cost and efficient renewable energy sources represents an important aim for the next years. Devices based on organic photovoltaics (OPVs) have undergone high performances. However, the required cost-efficiency balance to make a significant contribution to the global energy production is a remaining goal. This thesis reports the synthesis and characterization of conjugated molecules that can be employed for photovoltaic applications. The work is focused on the design of functional dyes for both bulk heterojunction (BHJ) solar cells and dye-sensitized solar cells (DSSC). The first chapter introduces the fundamentals of organic electronics, with a particular focus on photovoltaics. The use of functional dyes in the so called third-generation solar cells and and details of the principles behind the production of such technologies is covered. The second chapter describes the synthesis and characterization of a collection of new BODIPY derivatives. The materials were successfully applied as donor materials in BHJ solar cells and DSSCs and their performance was studied. The third chapter describes the synthesis and characterization of a library of thiophene-based molecules and presents a detailed investigation into the effect of alkyne spacers on the optoelectronic and BHJ properties of the materials. In chapter four, three generations of thiophene-based dyes that incorporate di-anchoring groups are designed, synthetized and tested in DSSCs. The dyes were used to gain knowledge about the structural parameters contributing to the power conversion efficiency of the di-anchoring architecture. The fifth chapter is devoted to the synthesis and characterization of DTS-based small molecules and covalently-linked donor-acceptor unimolecuar systems with the aim of preparing high efficiency BHJ solar cells. Finally, the sixth chapter focuses on the synthesis and characterization of thiophene-based macrocycles, and their investigation in BHJ solar cells, with interest in the possible host-guest interactions for supramolecular control of the BHJ morphology