Date of Award

12-2011

Document Type

Thesis

Degree Name

Master of Science (MS)

Legacy Department

Materials Science and Engineering

Advisor

Foulger, Stephen H

Committee Member

Luzinov , Igor A

Committee Member

Mefford , Olin T

Abstract

Organic light emitting diodes (OLED) have received a great deal of
attention in the research community in the past few decades. This
work focuses on OLEDs utilizing the donor-acceptor operational
approach. In specific a single layer device architecture with an
emissive layer of copolymerized hole and electron transport moieties
in an effort to frustrate phase segregation that can occur during
device operation. A new methacryalate based oxadiazole monomer,
4-[5-(biphenly-4-yl)- 1,3,4-oxadiazol-2-yl] phenyl methacrylate (mPBD) an electron transporter, was successfully synthesized. The new monomer was copolymerized with N-vinylcarbazole (VK), a hole transporter, to form statistical copolymers. The glass transition of the copolymers follows the Fox equation, indicating a lack of preferential
interactions between similar and dissimilar pendant groups. OLED
devices containing copolymers of varying composition and coumarin 6 were fabricated and tested. Copolymer devices surpassed 100 cd/m2 but failed to reach 1 cd/A efficiency. The copolymer with a 0.501 mole fraction VK proved to give the highest luminance and luminous efficiency. It is also of intrest to synthesize colloidal OLEDs for future printing applications. Homopolymer colloids of
poly(N-vinylcarbazole) (PVK) and poly(4-[5-(biphenly-4-yl)-
1,3,4-oxadiazol-2-yl] phenyl methacrylate) (PmPBD) were successfully synthesized and their corresponding colloidal copolymers were synthesized. The copolymer colloids exhibited an odd photoluminescent shift and broadening with colloid concentration. Reabsorption and then subsequently re-emission at a lower wavelength seems to be the best explanation for the broadening and bathochromic shift with increased colloid concentration.

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