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RESEARCH PRODUCT

Frequency-Downconversion Stability of PMMA Coatings in Hybrid White Light-Emitting Diodes

Fulvio CarusoFilippo SaianoRoberto MacalusoClaudio CaliEric FeltinMauro MoscaSalvatore Rinella

subject

Materials scienceInfraredSettore AGR/13 - Chimica Agraria02 engineering and technologyengineering.materialSettore ING-INF/01 - Elettronica01 natural sciencesCoating0103 physical sciencesMaterials ChemistryElectrical and Electronic EngineeringPhotodegradationDiode010302 applied physicschemistry.chemical_classificationSpin coatingbusiness.industryPMMA hybrid LEDs Lumogen polymer degradation photostability spin coatingPolymer021001 nanoscience & nanotechnologyCondensed Matter PhysicsElectronic Optical and Magnetic MaterialsColor rendering indexchemistryengineeringOptoelectronics0210 nano-technologybusinessLayer (electronics)

description

We report on the properties of a poly(methyl methacrylate)-based coating used as a host for an organic dye in hybrid white light-emitting diodes. The device is composed by a pump source, which is a standard inorganic GaN/InGaN blue light-emitting diode (LED) emitting at around 450 nm, and a spin-coated conversion layer making use of Lumogen® F Yellow 083. Under prolonged irradiation, the coating exhibits significant bleaching, thus degrading the color rendering performance of the LED. We present experimental results that confirm that the local temperature rise of the operating diode does not affect the conversion layer. It is also proven that, during the test, the photostability of the organic dye is compromised, resulting in a chromatic shift from Commission Internationale de l’Eclairage (CIE) (x;y) coordinates (0.30;0.39) towards the color of the pump (0.15;0.04). Besides photodegradation of the dye, we address a phenomenon attributed to modification of the polymer matrix activated by the LED’s blue light energy as confirmed by ultraviolet–visible and Fourier-transform infrared spectroscopic analyses. Three methods for improving the overall stability of the organic coating are presented.

yearjournalcountryeditionlanguage
2015-11-13Journal of Electronic Materials
https://doi.org/10.1007/s11664-015-4173-y