CHED 693 |
| Polymer light-emitting diodes (PLEDs) were fabricated for improved charge injection and transfer. Single-layer devices were constructed by spin-coating MEH-PPV [poly(2-methoxy,5-(2'ethylhexyloxy)-1,4-phenylene vinylene)] from 1,2-dichloroethane/toluene or toluene/THF onto ITO/glass substrates prior to application of a Ga-In eutectic. Devices were tested for longevity and luminescent output at turn-on voltages ranging from 3.0-12.0 V. Electroluminescence of the ITO/MEH-PPV/Ga-In diode at 12.0 V was characterized by "front-face" fluorometry. The majority of ITO/MEH-PPV/Ga-In structures exhibited no luminescence if modified at the ITO interface by acid etching (H2PO4), insertion of a PEDOT:PSS [poly(3,4-ethylene dioxythiophene) doped with polystyrene sulfonate] hole-injection layer, or self-assembly of a trichloro(1H, 1H, 2H, 2H)-perfluorooctylsilane monolayer. Thermal annealing at 90°C under nitrogen and/or doping with t-Bu-PBD [4-(5-(4-tert-Butyl phenyl)-1,3,4-oxadiazole-2-yl)-biphenyl-4'-yl] resulted in functioning devices with potentially brighter, more uniform luminescent output. Diodes encapsulated in epoxy to exclude atmosphere induced degradation demonstrated longer operational lifetimes and an observed shelf-life of over four months. |
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Undergraduate Research Poster Session: Polymer Chemistry
11:00 AM-1:00 PM, Monday, April 7, 2008 Morial Convention Center -- Hall A, Poster
Division of Chemical Education |