Developing Materials Enabling More Efficient and Sustainable LED Technology for Solid State Lighting

Lopes Rodrigues, Edward (2023) Developing Materials Enabling More Efficient and Sustainable LED Technology for Solid State Lighting. Masters thesis, UNSPECIFIED.

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Abstract

The project developed materials such as the one shown below based on phenanthrene and fluorene as starting material by attaching side chains to the molecule to adapt the material. The monomers were polymerised using the Suzuki coupling reaction or an organometallic dehalogenative polycondensation reaction. The resulting polymer was then characterised as nanoparticles. The synthesis of two polymer materials was completed including the monomer synthesis of the second material, with yields of up to 45% for the side chain addition step, and 30% for the bromination step. The polymers were successfully synthesised from these monomers, obtaining yields of 73% and 82%. Nanoparticle suspensions were then formed using 3 different methods including nanoprecipitation and mini-emulsion techniques. The nanoparticle sizes were then measured, and the stability and efficiency of both polymer nanoparticles were then measured. The results showed that moving to a phenanthrene-based polymer compared to a fluorene-based polymer led to greater stability in blue-emitting polymers. The increase in the size of the monomer unit reduces the efficiency of the phenanthrene polymer compared to the fluorene polymer which has greater efficiency. The reduction in efficiency is due to the greater chance of annihilation of the exciton-exciton singlet and triplet states as it has a larger absorption cross section and limited energy transfer within the polymer.