AASERT 92 - Synthesis and Properties of Complex Polyarylene Vinylenes.
Final rept. 1 Jun 93-31 Jul 96,
MASSACHUSETTS UNIV AMHERST DEPT OF POLYMER SCIENCE AND ENGINEERING
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A series of polymeric chromophores has been synthesized for use in polymeric light emitting diodes. These materials are based on the concept of alternating block copolymers containing a soft oligomethylene sequence and a hard chromophoric block based on an oligo arylene vinylene structure. Furthermore these materials can be blended to improve exciton confinement and enhance electroluminescence. For example, in a 11 weight ratio blend of a fully conjugated poly2,5-diheptoxy-p-phenylene vinylene-alt-2,5-dimethoxy-p-phenylene DHDMPPV with a conjugated-nonconjugated multiblock copolymer CNMBC poly1,8-octanedioxy-2,6-dimethoxy-1,4-phenylene-1,2-ethenylene-1 ,4-phenylene-1,2-ethenylene-1,4-phenylene-1,2-ethenylene-3,5-dimethoxy-1,4-phenylene, efficient energy transfer both in photoluminescence PL and electroluminescence EL from CNMBC to DHDMPPV was observed by measuring the absorption, PL, and EL spectra of DHDMPPV, CNMBC, and of their blend at room temperature RT and at 77K. The external EL quantum efficiency 0.03 photonelectron and the brightness 400 cdsq m of the DHDMPPV EL device was increased, respectively, to 0.12 photonelectron and 800 cdsq m, by blending. The measurements show this is achieved by confinement of injected holes and electrons in the blend resulting in enhanced probability of exciton formation. This confinement of injected charge carriers by blending is consistent with a large body of experimental results obtained here.
- Polymer Chemistry
- Physical Chemistry
- Electricity and Magnetism