Compatibilisation of blends of incompatible mesogens

• Main Author: Herbaut, Antoine Joel
• Published: University of Birmingham 2017
• Subjects: 547; QD Chemistry
• Online Access: https://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.707668

Controlling the morphology of blends of materials is crucial for organic optoelectronic devices. However, the blends are often made of incompatible materials, resulting in an undesirable macrophase separation. This thesis focusses on the addition of a third component into the immiscible blend of small molecules to control their morphology. After introducing the concept of organic solar cells and the liquid crystalline state of matter, the available methods to control the morphology of blends in these two fields will be reviewed. Model compounds based on triphenylene derivatives was first studied. After preparing two incompatible triphenylenes based on the immiscibility of their pendent chains, the introduction of tailor-made compatibilisers was shown to have a tremendous effect on the morphology by suppressing the macrophase separation between the incompatible materials to a reproducible micro-segregation. Our research was then focussed on incompatible functional materials showing high promises for solar cell application: the hexa-peri-hexabenzocoronene and the perylene diimide family. By applying the same concept as in the triphenylene derivatives, the incompatibility between hexa-peri-hexabenzocoronene and perylene diimide was introduced by the immiscibility of their pendent chains. The synthesis of a tailor-made functional dyad was successfully carried out and preliminary results of its effect on the compatibilisation of hexa-perihexabenzocoronene and perylene diimide was investigated.