Design and processing of charge transport polymer semiconductors and their applications in n-channel organic field effect transistors

Abstract

The molecular structures of polymeric semiconductors were strategically designed to impart electronic characteristics conducive to increasing electron-transport performance in organic field effect transistor devices. The polymers were synthesized by Stille polymerization, and optoelectronic properties of the materials investigated using spectroscopic and electrochemical analytical methods. The polymers were incorporated into transistor devices using blade-coating deposition methods, and the structures and topology of these thin films investigated using microscopy and X-ray spectroscopy techniques. Results indicated that the patterns of the orbital wavefunction distributions are as important in determining the final electronic properties of the polymers as the frontier energy levels of the component monomeric units in utilizing the ‘all-acceptor’ design strategy. The polymers synthesized successfully achieved electron-transport upon incorporation into field-effect transistor devices. The findings of this thesis suggest further refinement of common molecular semiconductor design strategies would benefit the development of high-performance polymeric semiconductors. Blade-coating processing studies on the development of polymeric nanofiber network formation within thin films and the impact on transistor performance are also examined. and the implications for further research are discussed.