AASERT 92 - Synthesis and Properties of Complex Polyarylene Vinylenes.
Abstract
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 1:1 weight ratio blend of a fully conjugated poly(2,5-diheptoxy-p-phenylene vinylene-alt-2,5-dimethoxy-p-phenylene) (DHDMPPV) with a conjugated-nonconjugated multiblock copolymer (CNMBC) poly(1,8-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% photon/electron) and the brightness (400 cd/sq m) of the DHDMPPV EL device was increased, respectively, to 0.12% photon/electron and 800 cd/sq 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.
Document Details
- Document Type
- Technical Report
- Publication Date
- Oct 01, 1996
- Accession Number
- ADA318383
Entities
People
- F. E. Karasz
Organizations
- University of Massachusetts Amherst