Luminescent copolymers for applications in multicolor-light-emitting devices

Light‐emitting diodes based on organic materials [organic light‐emitting diodes (OLEDs)] have attracted much interest over the past decade. Several different attempts have been made to realize multicolor OLEDs. This article describes a new approach based on energy transfer in a donor/acceptor system. A copolymer containing both donor and acceptor compounds as comonomer units is prepared. The polymer consists of a derivative of a luminescent dye [4‐dicyanmethylene‐2‐methyl‐6‐4H‐pyran (DCM); acceptor compound], which is copolymerized with fluorene (donor compound) to combine the properties of an electroactive polymer with a highly luminescent dye. Photochemical processing is achieved by UV irradiation of this copolymer in the presence of gaseous trialkylsilanes. This reagent selectively saturates the CC bonds in the DCM comonomer units while leaving the fluorene units essentially unaffected. As a result of the photochemical process, the red electroluminescence of the acceptor compound vanishes, and the blue‐green electroluminescence from the polyfluorene units is recovered. Compared with previous approaches based on polymer blends, this copolymer approach avoids problems associated with phase‐separation phenomena in the active layer of OLEDs. © 2006Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 44: 4317–4327, 2006 A donor/acceptor copolymer has been prepared by the Suzuki coupling of a derivative of a luminescent dye[4‐dicyanmethyl ene‐2‐methyl‐6‐4H‐pyran (DCM); acceptor] with fluorene (donor). UV irradiation of this copolymer under a trimethylsilane atmosphere leads to a selective saturation of CC bonds in the DCM units. As a result, the energy transfer in the copolymer is suppressed, and both photoluminescence and electroluminescence spectra undergo significant changes. Color‐tunable organic light‐emitting diodes based on this donor/acceptor copolymer are presented in this article.