Accession Number : ADA318383
Title : AASERT 92 - Synthesis and Properties of Complex Polyarylene Vinylenes.
Descriptive Note : Final rept. 1 Jun 93-31 Jul 96,
Corporate Author : MASSACHUSETTS UNIV AMHERST DEPT OF POLYMER SCIENCE AND ENGINEERING
Personal Author(s) : Karasz, F. E.
PDF Url : ADA318383
Report Date : OCT 1996
Pagination or Media Count : 11
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.
Descriptors : *POLYMERS, *BLOCK COPOLYMERS, BLENDING, SYNTHESIS, CHROMOPHORES, ELECTROLUMINESCENCE, PHOTOLUMINESCENCE, PROBABILITY, CHARGE CARRIERS, ENERGY TRANSFER, ROOM TEMPERATURE, ELECTRONS, SPECTRA, QUANTUM EFFICIENCY, EXTERNAL, CONFINEMENT(GENERAL), ABSORPTION, LIGHT EMITTING DIODES, EXCITONS.
Subject Categories : Polymer Chemistry
Electricity and Magnetism
Distribution Statement : APPROVED FOR PUBLIC RELEASE