Electron-deficient conjugated materials

Loading...
Thumbnail Image
Date
2018
Journal Title
Journal ISSN
Volume Title
Publisher
University of Alabama Libraries
Abstract

The development of new conjugated materials with tailored properties is in high demand for applications in organic electronics. This has led to conjugated materials receiving a great deal of research attention over the last few decades. One efficient method to prepare these novel conjugated small molecules and polymers is the incorporation of p-block elements into conjugated systems. In Chapter 2, a new phosphafluorene is synthesized and copolymerized to produce a donor-acceptor (D-A) conjugated copolymer PPF-BDTT. Direct post-polymerization modification of PPF-BDTT was performed on the phosphorus center to prepare the phosphine sulfide polymer PPF-BDTT-S and phosphine gold chloride polymer PPF-BDTT-Au. These D-A polymers have been fully characterized, and their applications in organic solar cells was also investigated. In Chapter 3, three air-stable difuran small molecules were synthesized by the incorporation of phosphorus, germanium, and silicon. The good stability is partially due to the σ*-π* conjugation interaction between p-block elements and the pi systems. These molecules show strong absorption in the UV region and intense emissions. The phosphorus bridged difuran was also copolymerized with fluorene to produce a D-A conjugated polymer. In Chapter 4, bithiazole (BTz) was functionalized with a 9-borabicyclononane (BBN) moiety to produce a boronium molecule BTz-BBN. With similar synthetic methods, two conjugated organoboronium polymers PFOBPy-BBN and PFOBTz-BBN were developed, which demonstrated a novel method to prepare conjugated boronium polymers in high yield. PFOBPy-BBN and PFOBTz-BBN were studied optically and electrochemically. In Chapter 5, benzothiophene dioxide was selected to prepare the non-fullerene acceptor ITBC with an acceptor-donor-acceptor structure. The strong electron-withdrawing sulfonyl acceptor units lead to extended UV-Vis absorption and low frontier molecular orbital energy levels with a narrow bandgap. A power conversion efficiency of 4.17 % was achieved by fabricating organic solar cells with polymer FTAZ as the donor and ITBC as the acceptor. In Chapter 6, a chlorinated bifuran small molecule ClBF was synthesized, and a series of random copolymers (PNDI-ClBFx) using ClBF and naphthalene diimide were prepared. These polymers exhibit strong and broad absorption, and the low-lying frontier energy levels of PNDI-ClBFx are suitable as polymer acceptors in all-polymer solar cells applications.

Description
Electronic Thesis or Dissertation
Keywords
Organic chemistry
Citation