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Polymer Light Emitting Devices

#0872


Organic Polymer Light Emitting Devices

Tech Area / Field

  • MAT-ELE/Organic and Electronics Materials/Materials

Status
8 Project completed

Registration date
20.02.1997

Completion date
25.03.2002

Senior Project Manager
Komashko B A

Leading Institute
Institute of Electrochemistry, Russia, Moscow

Supporting institutes

  • Institute of Biochemical Physics, Russia, Moscow

Collaborators

  • University of New Mexico / Department of Physics and Astronomy/Center for Advanced Studies, USA, NM, Albuquerque\nUniversity of Cambridge / Department of Physics, UK, Cambridge\nPhilipps Universität / Department of Physical Chemistry, Germany, Marburg\nKatholieke Universiteit, Belgium, Leuven\nChalmers University of Technology / Department of Polymeric Materials, Sweden, Göteborg\nFukui University / Department of Applied Physics, Japan, Fukui\nUniversity of Missouri-Rolla, USA, MO, Rolla\nNapier University, UK, Edinburgh

Project summary

The goal of the proposed Project is investigation of the mechanism of electroluminescence in polymeric systems and determination of the optimal conditions of its occurrence in order to select the most efficient macromolecular luminophores and the most suitable polymeric layers which will be able to carry significant injected currents at low voltage. Among these polymers are newly synthesized promising classes of polymers - poly (hydroxyamino-esters), aromatic polyimides, vacuum-deposited polyaniline, intercalated carbon materials, along with highly efficient low-molecular-weight photoluminophores: 2-phenyl-4H-3,1-benzoxazinon-4, oxadiazoles and widely used 8-hydroxyquinoline metal complexes. Photophysical and electrophysical properties of these materials make them suitable for usage in organic light-emitting diodes (OLEDs). We also intend to investigate electroluminescent layers made of thin films of vacuum deposited polyconjugated polymers such as polythiophene, polypyrrole, PPV and others.

We intend to increase significantly (up to 10%) the quantum efficiency (photon/electron) of the polymer OLEDs and prolong the operation time of the devices. These parameters depend to a large extent on the physical and chemical aging of the active light-emitting and transporting polymer layers. Therefore we will investigate the influence of the physico-chemical state of the polymers, which is determined by the polymer specific free volume, Tg value, orientation of the macromolecules, the prehistory of polymer specimen etc., on the quantum yield of photoluminescence, the charge carrier transport and hence the efficiency of electroluminescence. In order to develop new injecting layers and methods of manufacturing of stable electroluminescent images, the processes of photodoping of electroconducting polymers and photochemical formation of luminescent elemento-organic complexes will be investigated.

Particular attention will be paid to the investigation of charge carrier mobility in polymer matrices and preparation of the trapless polymer layers with high charge carrier mobility. This is important for the protection of the OLEDs from the Joule heating. In this context a theoretical analysis of charge carrier transport in disordered and locally ordered polymeric matrices will be carried out.

Results of these studies will help us to find out the relationship between the characteristics of the electroluminescence and the transport, physico-chemical and structure properties of the polymer materials. As a final result of the investigation, highly efficient thermostable OLEDs will be produced.

Possible roles of international collaborators are:


(1) Synthesis and chemical modification of new polymer materials for electroluminescent layers and investigation of the morphology of polymer layers (group of prof. G.W.H. Milburn)
(2) Investigation of spectral properties and relaxation processes hi electroluminescent compounds using second harmonic generation methods (group of prof. Rychwalski)
(3) Joint theoretical researches on charge carrier transport in disordered organic matrices (groups of prof. Dunlap, prof. Parris, prof. Aoki, prof. Soos, prof. Bassler)
(4) Mesurements of charge carrier drift mobilities in electroactive compounds (group of prof. Bassler)
(5) Investigation of propagation of chemical reaction fronts in conductive polymers using unique microvisualization technique (group of prof. Aoki).


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