Degree Type

Dissertation

Date of Award

2005

Degree Name

Doctor of Philosophy

Department

Physics and Astronomy

First Advisor

Joseph Shinar

Abstract

The Origin of the PLDMR enhancing signal and various aspects of the device physics of small molecular doped PLEDs were described and discussed. The difference between the delay model and the quenching model was explained. The microwave- and laser-modulation-frequency dependence of the PLDMR and DM-PLDMR, respectively, in MEH-PPV, invalidated the delay models, questioning reports of SE yields exceeding 25% in fluorescent OLEDs. Rather, the results were consistent with the quenching model where SEs are annihilated by TEs and polarons. For the device, the proper procedure for the treatment of the PEDOT/PSS layer with EG was suggested and a 10 fold enhancement was shown. The radiance of the device showed ~10 fold improvement with an addition of EG treated PEDOT/PSS layer and ~5 fold with 12 nm thick BCP and Alga layer. With both layers, a 45 fold improvement in the brightness, 8 fold in the external quantum efficiency, and 7 fold in the power efficiency were achieved. Also, for WOLED, the addition of the DPVBi layer on top of the DPVBi doped PVK improved device performance ~3 fold by reducing quenching by the cathode. The optimized device structure was suggested and tested. They exhibited white emission with a brightness of 9000 Cd/m2 at a current density of 1000 mA/cm 2 and the maximal quantum efficiency of 2.2% at 16 V.

DOI

https://doi.org/10.31274/rtd-180813-11835

Publisher

Digital Repository @ Iowa State University, http://lib.dr.iastate.edu/

Copyright Owner

Moon-Ky Lee

Language

en

Proquest ID

AAI3200437

File Format

application/pdf

File Size

81 pages

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