Date of Award

Fall 12-2017

Degree Type

Dissertation

Degree Name

Doctor of Philosophy (PhD)

Department

Polymers and High Performance Materials

Committee Chair

Sarah E. Morgan

Committee Chair Department

Polymers and High Performance Materials

Committee Member 2

Song Guo

Committee Member 2 Department

Chemistry and Biochemistry

Committee Member 3

James W. Rawlins

Committee Member 3 Department

Polymers and High Performance Materials

Committee Member 4

Robson F. Storey

Committee Member 4 Department

Polymers and High Performance Materials

Committee Member 5

Gopinath Subramanian

Committee Member 5 Department

Polymers and High Performance Materials

Abstract

Organic photovoltaics (OPVs) have undergone intense development in recent years due to their potential to produce inexpensive, flexible, lightweight, and portable solar cells utilizing organic photoactive materials. Polymer-based OPVs have recently surpassed the 10 % in laboratory-scale devices, but require strict processing conditions in inert environments. Materials and processing methods that are workable in air are therefore desired. In addition to the light-absorbing and charge transport properties of the active layer materials, the morphology, crystallinity and orientation of the components of the phase-separated blend are paramount in determining OPV device performance This dissertation explores the processing of the model polymer OPV system under environmental conditions, and how that processing affects the morphology of the active layer at the molecular scale. Advanced x-ray scattering was utilized along with conventional laboratory characterization to mechanistically determine how the processing steps involved affected the performance of the final devices. Additionally, a number of new compounds with hypothesized air stability were synthesized and characterized. Light-absorbing polyhedral oligomeric silsesquioxane (POSS) molecules were synthesized and incorporated into the active layer of a model polymer OPV to act as conductive nanostructuring agents. The air-stable thieno[3,4-b]pyrazine subunit was copolymerized into a donor-acceptor copolymer and used as a broadly-absorbing donor polymer in the conventional polymer:fullerene OPV architecture. Finally, a series of non-fullerene acceptors was synthesized based on perylene bisimide, an air-stable dye that has shown wide use in organic electronics due to its broad absorption and good electron transport capability, and utilized in polymer OPV devices. Alternate, higher-yielding pathways for the synthesis of intermediate compounds required for the target compounds were found, which expands available architectures available for perylene bisimide-based materials.

ORCID ID

0000-0002-8010-4795

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