Structure-property relationships of conjugated polymers

Conjugated polymers for application in optoelectronic devices have been an increasingly popular topic of research over the past two decades, with photovoltaic devices incorporating conjugated polymers now nearing large-scale commercialisation. This work focuses on the structure-property relationships of conjugated polymers. Firstly, the difference in backbone structure between an alternating copolymer and its statistical counterpart are investigated, the differences in backbone sequence is elucidated by kinetic and microscopic techniques. The resulting polymers are found to be more gradient or block-like and form better BHJ blends with the PC61BM acceptor and have deeper HOMOs resulting in the observed increase in PCE. Subsequently, alterations to the catalytic system for the synthesis of statistical copolymer by Stille polycondensation are investigated. Variations in the ligands electronic and steric effects are shown to have a profound effect on the relative rates of monomer conversion. Changing the catalyst directly effects the backbone sequence of the polymer. Polymers synthesised using various catalysts are investigated and their optoelectronic and morphological properties are discussed related to the monomer sequence. Finally, well-defined all-conjugated block copolymers are investigated. Electron deficient PTBT and electron rich PTBnDT blocks are synthesised and characterised. Each of the homoblocks demonstrate distinctly different miscibility and film morphology with the PC61BM electron acceptor. When coupled, the resulting block copolymers show signs of micro-phase separation and the viability of block copolymers as a means of domain size control is investigated