Chemistry and Chemical Biology ETDs

Publication Date

Fall 10-31-2018

Abstract

Conjugated polymers have found widespread applications in flexible and printable electronic devices, among which poly(thienylene vinylene) (PTV) displays outstanding optoelectronic properties and promising applications. However, further studies of its structure-property-function relationship have been greatly impeded mainly due to the synthetic difficulty of generating new structures beyond its rudimentary form.

To further investigate this class of material, I have developed a facile methodology for the preparation of structurally diverse poly(chalcogenylene vinylene)s (PCVs) through a combination of acyclic diene metathesis (ADMET) polymerization and post-polymerization modification techniques. Specifically, a series of halogenated and cross-conjugated PCVs have been designed and synthesized, followed by complete characterizations. It was found the physical and optoelectronic properties of the obtained polymers can be fine-tuned through introducing halogen atoms and specific conjugated side chains. Interestingly, the PTVs with strong electron withdrawing cyano groups were found to be emissive, which is rarely observed in this class of materials. The newly prepared polymers combining with PCBM (electron acceptor) were eventually fabricated into solar cell devices. Power conversion efficiency of ca. 1.6%, 2-fold higher than the parent PTV, was achieved, resulting from the optimized energy levels, crystallinity and broadened absorption via chemical modifications. Our methodologies provide a facile tool to effectively diversify PTV’s structures and then systematically study their structure-property-function relationships, which enhanced our basic understanding on this type of materials and will potentially lead to new materials for advanced electronic applications.

The other part of the dissertation is about the preparation, photophysical studies and application of a conjugated Pt-containing small molecule. The incorporation of Pt atom into this molecule is supposed to increase the triplet exciton generation after radiation due to the heavy atom effect, offering us the opportunity to investigate the formation and transport of the triplet excitons and eventually capture them for solar cells. This acceptor is composed of our previously designed Pt-containing electron-rich unit in the middle and strong electron-deficient units on both sides. It was found that this acceptor-donor-acceptor Pt-containing compound possesses broad absorption from 300 to 1000 nm, good crystallinity and low LUMO energy level, which are prerequisite for a good acceptor material of organic solar cells. The device performance of the Pt-containing compound is currently under investigation.

Language

English

Keywords

poly(thienylene vinylene), poly(selenylene vinylene), acyclic diene metathesis, post-polymerization modification, photoluminescent PTV, halogenated PTV and PSV

Document Type

Dissertation

Degree Name

Chemistry

Level of Degree

Doctoral

Department Name

Department of Chemistry and Chemical Biology

First Committee Member (Chair)

Yang Qin

Second Committee Member

Ramesh Giri

Third Committee Member

John K. Grey

Fourth Committee Member

Mehran Tehrani

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