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Polyurethanes with covalent attached fluorescent dyes as deep red emitting materials

: Janietz, S.; Krüger, H.; Wedel, A.; Fischer, B.


Kafafi, Z.H. ; Society of Photo-Optical Instrumentation Engineers -SPIE-, Bellingham/Wash.:
Organic Light-Emitting Materials and Devices VI : 8 - 10 July 2002, Seattle, Washington, USA
Bellingham/Wash.: SPIE, 2003 (SPIE Proceedings Series 4800)
ISBN: 0-8194-4568-1
Conference "Organic Light-Emitting Materials and Devices" <6, 2002, Seattle/Wash.>
Conference Paper
Fraunhofer IAP ()

A unusual way is presented to obtain a new class of deep red emitting polymers. Polyurethanes with covalently attached fluorescent dyes were developed. The DCM-dye seems to be a favorable candidate but it has no reactive groups for linking into a polymer structure. DCM can be synthesized by the monofunctional addition of (2,6-dimethyl-4H-pyrane-4-ylidene)-malononitrile with 4-dimethylaminobenzaldehyde. We realized a bifunctional condensation of the pyrane with N-methyl-N-(2-hydroxyethyl)-4-aminobenzaldehyde to enlarge the conjugated system and to shift the emission maximum to more than 650 nm. Simultaneously we introduced two reactive hydroxy terminal groups into the dye molecule. Using this functionality we were able to synthesize several new polyurethanes with covalently attached DCM dye in the main chain. By co-condensation with non-dye molecules like N,N-bis-(2-hydroxyethyl)-aniline or butan-1,4-diole the dye content in the main chain can be varied and the influence of the absorption and emission behavior can be studied. Red emitting device structures were realized and some of the device properties will be given. It will be shown that the stability and the lifetime of the device can be increased by simple structure modification of the polyurethane, e.g. alkylation of the urethane groups or the change of the co-components.