ORGN 763 |
| Design and synthesis of novel optoelectronic devices requires deeper understanding of the photophysics of model oligomeric compounds, and comparison of their properties to those of structurally related polymers. This work was aimed at synthesis, characterization and electronic spectroscopy of alternating block copolymer analogues of model compound 1. Alternating block conjugated systems 2, 3, 4 and 5 were synthesized using step–growth polymerization method yielding polymers with Mw ranging from 70000 to 1000 and having a broad distribution curve with PDI ranging from 3 to1 based on GPC analysis. Characterization was done using NMR, IR, UV-vis and fluorescence spectroscopy. LED characteristics were also studied with these species with the assistance of Dr. Ali Cirpan of the Karasz group in the Polymer Science and Engineering department at University of Massachusetts Amherst. All the compounds have two UV–vis absorbance bands, one at 304-310 nm and other at 350 – 370 nm. Fluorescence emission is found in the 390–400 nm region upon excitation at various wavelengths. Neat solid films of all the compounds show UV–vis absorbance in same region (maximum shift of 5 nm) as in the solution phase compared to a large red shift (60 nm) in the model compound. Emission spectra of neat solid films of compounds 7-10 shows a slight red shift of 10-20 nm compared to the solution phase spectra, whereas the red shift is much higher (75 nm) in case of the model compound. Fluorescence quantum yields in THF at room temperature are 0.60, 0.24, 0.51 and 0.58 respectively for compounds 2, 3, 4 and 5. All of the compounds except 2 show electroluminescence with a λ max around 500 -520 nm and turn – on voltages of 6-8 volts.
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Materials, Devices, and Switches
8:00 AM-12:00 PM, Thursday, March 29, 2007 McCormick Place Lakeside -- Room E450 A/B, Level 4, Oral
Division of Organic Chemistry |
