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White emission from organic and inorganic dyes dispersed polymers excited by GaN blue LEDs

1999; SPIE; Linguagem: Inglês

10.1117/12.372735

1996-756X

Jacques Tardy, Laurent Berthelot,

Conducting polymers and applications

This work reports on color controlled light converters fabricated from organic dyes (coumarin, DCM) and luminescent organic (Alq 3 ) and inorganic (SrGa 2 S 4 :Eu ++ ) molecules dispersed in a transparent polymer host matrix. These blends were pumped with a commercial GaN blue LED having a peak emission at 430 nm. First are reported the photoluminescence spectra of Alq 3 - DCM and coumarin-SrGa 2 S 4 :Eu ++ -DCM blends. By photoexcitation of these blends with GaN blue LEDs (which is partially absorbed by the dispersed dyes), it has been observed that the color can be tuned from blue to red depending on the composition. In particular, very pure white emitting hybridLEDs could have been obtained with organic- inorganic blends. Observed luminescence is due to cascade light absorption and emission from the various dyes in the blend. The influence of the polymer host matrix on the emitted color was also evidenced. Our results show how multicolor and white emitters could be fabricated with commercially available organic materials and rare earth doped inorganic dyes.