Organic semiconductors combine the attractive properties of common plastics with electrical conductivities typical of metals, enabling their use across a wide range of emerging technologies. The synthetic utility of these materials allows the optoelectronics to be manipulated towards a diverse set of applications, ranging from photovoltaics to biological sensors. As such this thesis spans across four unique disciplines with organic semiconductors acting as the underlying motif throughout.
Chapter 2 focuses on singlet fission, a third-generation photovoltaic technology, aiming to surpass the Shockley-Queisser limit of solar cell efficiency. The synthesis of an original series of indenofluorene dimers, separated by a phenyl bridging unit, is presented herein. The complex optoelectronics of this system were then investigated using transient absorption spectroscopy to elucidate the feasibility for singlet fission. The indenofluorene backbone is further investigated in Chapter 3 as a spin sink material, demonstrating the versatility of this backbone. The quinoidal nature of this unit, alongside the corresponding thiophene-containing analogue of indacenodithiophene and a series of higher biradical character materials are synthesised and probed within a unique spintronic device, specifically the ferromagnetic linewidth broadening experiment.
Chapter 4 moves towards the area of organic semiconducting polymers, presenting the effects of sidechain manipulation on the mode of operation for a series of novel n-type polymers containing a fused aromatic backbone and ethylene glycol solubilising chains. These fused systems, synthesised using a metal catalyst free Aldol polycondensation, show excellent ambient stability and promise as semiconductor materials in both thermoelectric devices and organic electrochemical transistors (OECTs). Complementary to the n-type OECT channel materials in Chapter 4, a series of p-type materials is showcased in Chapter 5, investigating the effect of hybrid polarity (alkyl and ethylene glycol based) sidechains on OECT device performance. The four disciplines detailed herein are just a sampling of the versatility of organic semiconducting materials.Open Acces
