Functional molecular liquids for singlet fission and spintronics

Abstract

Functional molecular liquids (FMLs) are an emerging field in organic research due to their distinct advantages over solid materials such as ease of handling, processability, high thermal stability, flexibility and their versatile optoelectronic properties. This thesis describes the synthesis and potential of liquid organic chromophores in two novel concepts in synthetic organic chemistry: singlet fission in FMLs and FMLs for organic spintronics. Chapter 01 gives a fundamental overview on FMLs including their key properties, their potential applications and a comprehensive exploration of the strategies employed to achieve liquefaction. Chapter 02 presents the role of liquidity in singlet fission from the motivation of answering the Cristopher J. Bardeen’s question regarding the enhanced singlet fission efficiency of molten rubrene. The design principles, synthesis strategies and characterization of rubrene derivatives are explained in this chapter up to the rubrene in solid state unsubstituted intermediates and up to the stage of propargyl alcohols in novel substituted liquid rubrene derivatives. This chapter explains the design principles, synthesis strategies and characterization of rubrene derivatives starting from solid-state unsubstituted intermediates and progressing to the formation of novel substituted liquid rubrene derivatives, specifically up to the stage involving propargyl alcohols. Chapter 03 extends the concept of FMLs into the organic spintronics by exploring how liquidity impacts the spin transport and stability of radicals and merge the two concepts inspired by the recent studies of Takahashi Nakanishi’s spin hydrodynamic generation. The chapter explains the synthesis of stable, solid state organic radicals with propensity to liquefaction is described in this chapter. Overall, this thesis demonstrates that introducing liquidity into functional organic materials can be used to control electronic, photophysical and spin dependent properties which opens new pathways in next generation of optoelectronic, photovoltaics and spintronic devices.