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Proceedings Paper

Covalent bonding of coumarin molecules to sol-gel matrices for organic light-emitting device applications
Author(s): Ari H. O. Karkkainen; Osmo E. O. Hormi; Juha T. Rantala
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Paper Abstract

Coumarin molecules are widely used as laser dyes and their luminescence properties show a large potential for their use as light emitters in organic light emitting devices. These molecules however are lacking of photo, chemical and thermal stability. At the outset, the fact that when the coumarin or other organic active molecules are covalently bonded to a metal oxide host, the stability properties can be improved. In this paper we outline the synthesis of several different coumarin-3-carboxylic acids by using a one-pot synthesis from dipotassium o-methoxybenzylidenemalonates. We also outline a preparative route for the synthesis of corresponding coumarin-3-carboxylic amides with a side chain containing terminal trimethyoxysilane functionality, which allows the creation of a covalent bond between the molecule and a silicon oxide host matrix. These silylated coumarins are then covalently bonded through a sol-gel method to a developing siloxane host matrix. The silicon matrix materials have been synthesized through hydrolysis and simultaneous condensation of metalalkoxides such as phenylmethyltrimethoxysilane. Coumarin dyes are bonded in- situ to the developing matrix during the preparation of the matrix. The excitation and emission spectra of these molecules are examined in liquid phase to evaluate the effect of varying substitution pattern on luminescence characteristics. The photo luminescence characteristics are also measured from a solid thin film to explore the effect of the matrix on emission wavelengths. These materials show potentiality for their applications in thin film electro luminescence devices whose fabrication and properties are finally discussed.

Paper Details

Date Published: 2 May 2000
PDF: 16 pages
Proc. SPIE 3943, Sol-Gel Optics V, (2 May 2000); doi: 10.1117/12.384338
Show Author Affiliations
Ari H. O. Karkkainen, VTT Electronics (Finland)
Osmo E. O. Hormi, Univ. of Oulu (Finland)
Juha T. Rantala, VTT Electronics (Finland)

Published in SPIE Proceedings Vol. 3943:
Sol-Gel Optics V
Bruce S. Dunn; Edward J. A. Pope; Helmut K. Schmidt; Masayuki Yamane, Editor(s)

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