Synthesis and characterisation of molecules with optoelectronic applications

This thesis describes the synthesis and characterisation of conjugated materials, and their optoelectronic applications. The first chapter introduces the concept of solar cells and describes the most common types of solar cells used nowadays, including examples of some of the best performing materials. The second chapter describes the donor-functionalised synthesis of a small library of DPP derivatives with optoelectronic applications. DPP derivatives were used to gain knowledge about the physical parameters contributing to better PCE in organic solar cells, others were used as donors for BHJSC giving a highest PCE of 1.76%. Finally one DPP derivative proved to be an efficient fluoride chemosensor, able to selectively detect fluoride in the presence of other anions by means of colour change (and absorbance in the near infrared), and a change in its 1H NMR spectrum. The third chapter describes the one-pot synthesis of BODIPY molecules that can be further tuned to adjust their photophysical properties. These derivatives were used as donors for BHJSC giving a highest PCE of 0.45%. The absorption and emission properties of the molecules were studied, and it was found that the intensity of the emission depends on the electron richness of the substituent in the meso position. Some derivatives proved not to be fluorescent, whereas others exhibited extremely small Stokes shifts, sometimes as low as 1 nm. Chapter 4 describes the synthesis of a spirofluorene and a copper complex derivative with the aim of preparing molecules that could self-assemble forming 3D networks, in order to improve the dimensionality of the system. Their photophysical properties were studied, and the molecules proved to be fluorescent with large Stokes shifts, sometimes up to 100 nm. Chapter 5 describes the synthesis of fullerene derivatives with optoelectronic properties. One of the most successful derivatives was involved in a supramolecular chemistry study, to investigate how recognition-mediated assembly can lead to effective charge transfer from a quantum dot. Finally Chapter 6 describes a series of dyes synthesised using a simple 2/3 step synthetic pathway. DSSC were fabricated and the best performing dye with a 2 step synthetic route gave a PCE of 2.32%, whereas the best performing dye with a 3 step synthetic route gave a PCE of 4.35%. The high PCE of these types of dyes considering their ease of preparation makes their large-scale synthesis commercially feasible