Award Date

5-1-2016

Degree Type

Thesis

Degree Name

Master of Science (MS)

Department

Chemistry and Biochemistry

First Committee Member

Dong-Chan Lee

Second Committee Member

Gary Kleiger

Third Committee Member

Kathleen Robins

Fourth Committee Member

Woosoon Yim

Number of Pages

82

Abstract

Development of electron-accepting (n-type) semiconductors used in organic photovoltaic cells and field effect transistors has been an area of research with less advancement compared to their electron-donating (p-type) counterparts. Currently, the highest performing n-type semiconductor is a fullerene-based derivative (PCBM) with a favorable ELUMO of -4.08 eV. However, PCBM has limited absorption in the visible region and fixed electron affinity. This work focuses on the development of self-assembling n-type materials with controllable electronic properties by strategically lowering ELUMO to a level comparable to PCBM. Molecular design follows an acceptor-acceptor'-acceptor (A-A'-A) configuration; with A being two 2,3-dioctyloxyphenazine substituents connected to A’ with a C-C triple bond. A’ was altered to increase the electron deficiency using benzothiadiazole (BTD), naphthalene diimide (NDI), and perylene-tetracarboxylic diimide (PTCDI). Based on this molecular design, four new n-type materials (BTD-P, NDI-P-1, NDI-P-2, PTCDI-P) were successfully synthesized with low ELUMO values of -3.34 eV, -3.90 eV, -3.90, and -3.97 eV, respectively. Photophysical, thermal, and electrochemical properties were studied using UV-Visible absorption and fluorescence emission spectroscopy, differential scanning calorimetry, thermogravimetric analysis, and cyclic voltammetry. Theoretical evaluations were conducted to understand the experimental electronic properties. Charge-transfer (CT) was also used to test the accepting properties of the title molecules when paired with a pyrene donor. Successful CT results were seen using NDI-P-1, which were confirmed through UV-Vis and fluorescence spectroscopy. The morphology of the CT complex was studied with polarized optical microscopy (POM). Additionally, fluorescence resonance energy transfer (FRET) through organogelation was studied with BTD-P as a donor with NDI-P-2 as an acceptor. It was found that FRET was efficient even at low acceptor concentration of 5mole%. FRET results were characterized with fluorescence spectroscopy and POM.

Keywords

Molecular Design; Organic Chemistry; Semiconductors

Disciplines

Chemistry

File Format

pdf

File Size

3500 KB

Degree Grantor

University of Nevada, Las Vegas

Language

English

Rights

IN COPYRIGHT. For more information about this rights statement, please visit http://rightsstatements.org/vocab/InC/1.0/

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