Alexandria Digital Research Library

Relating Film Structure/Microstructure on Device Function/Microproperties in Conjugated Polymers and Polymer/Small Molecule Blends

Cochran, Justin Enir
Degree Grantor:
University of California, Santa Barbara. Chemistry
Degree Supervisor:
Michael L. Chabinyc and Thuc-Quyen Nguyen
Place of Publication:
[Santa Barbara, Calif.]
University of California, Santa Barbara
Creation Date:
Issued Date:
Chemistry, Organic, Chemistry, Polymer, Engineering, Materials Science, and Chemistry, Molecular
Conjugated Polymers
Organic Electronics
Semiconducting Polymers
Dissertations, Academic and Online resources
Ph.D.--University of California, Santa Barbara, 2014

Over the last twenty years conjugated organic materials, polymers and small molecules, have attracted broad interest due to their potential applications in the field of solution processed low cost electronics. Due to their semi/polycrystalline nature the spatial arrangement of crystallites and disordered regions in the film have a significant influence over charge transport properties. Structure-Function relationships are universal; consequently, the focus of my research thesis is to relate the film structure/microstructure to device performance and micro-properties, specifically in thin film transistors and bulk conductivity measurements. My initial research focus was on how modification of a semiconducting polymers backbone alters the packing structure and in turn impacts device performance.

We then focused on how modification of TFT interface microstructures by altering between dielectric surfaces changes the orientaional correlation length in the semiconductors crystalline domains which in turn directly impacts the field effect mobility. The final two projects focused on doping conjugated polymers with small molecular acceptors. The purpose was to understand how bulk packing dominates conductivity in order to better understand what appears to be a universal transport behavior in these blends. These insights into the structural changes provide a platform under which to analyze the electrical measurements where significant changes in conductivity were observed at high acceptor concentrations but results showed dependence upon pre and post processing conditions.

As expected, increases in film conductivity scaled with acceptor concentration but of special interest is how the conductivity showed temperature stability upon annealing, even increasing under certain conditions, near the polymer liquid crystal transition temperature and then decreasing below the as cast baseline at higher annealing temperatures. The electrical study combined with the structural analysis provided insight on the location of the small molecule dopants and how they directly impact film properties.

Physical Description:
1 online resource (251 pages)
UCSB electronic theses and dissertations
Catalog System Number:
Inc.icon only.dark In Copyright
Copyright Holder:
Justin Cochran
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