Committee Members:

Prof. Natalie Stingelin, MSE/ChBE

Prof. Shannon Yee, ME

Prof. John Reynolds, CHEM/MSE

Prof. Faisal Alamgir, MSE

Prof. Mark Losego, MSE

Prof. Erin Ratcliff, The University of Arizona

Examining thermal and charge transport in organic materials with Pi-electron interactions

Abstract:

Organic materials continue to be explored as the active component in wearable, flexible electronics and, more recently, in thermal devices. Their low-temperature thermal transitions and extensive chemical tunability promise realization of a variety of technology platforms, including thermal switches, devices that dynamically control the flow of heat, and thermoelectric generators, devices that convert heat into electrical energy or vice versa. Despite these opportunities, the physical and electronic characteristics that lead to different thermal and charge transport in organic materials needs to be further examined.  

This proposal defense introduces three different chemistries and examines how subtly tuning an organic material’s chemical structure alters the thermal and electronic properties. First, the thermal properties will be examined. Specifically, the vibronic contribution to thermal conductivity of a conjugated monomer topochemically polymerizing into a macromolecular structure will be measured, and the results will be contextualized by comparing thermal switching performance. Second, the electronic properties of a family of semiconducting polymers with removable side chains will be assessed. The structure-property relationship of these semiconducting polymers will be surveyed as a potential route to optimizing thermal switches based on strong electronic contributions. Third, semiconducting polymeric systems with contrasting charge transport properties will be produced via physical blending versus block copolymerization. We explain how the chemical versatility of organic materials can be utilized to optimize their thermoelectric performance. In each system, the physical and electronic characteristics are correlated to the measured macroscopic properties. The impact of this thesis work is to provide a detailed understanding of what characteristics lead to different transport behavior in organic materials.