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Microstructures électroluminescentes organiques: application à la gestion de l'émission lumineuse.

Abstract : The present work deals with the control of the light emission properties in luminescent polymer films by means of periodic microstructuration of the films, in the optical wavelength scale.
Firstly we have investigated the effect of a transient perturbation of the film optical constants on its emission properties. The transient gratings are produced from the interferences of a doubled or tripled pulsed Nd:Yag laser. The first evidence of the action of periodical structures on the emission is the induction of a laser effect using a «distributed feedback» (DFB) configuration. The result of a modification of the grating and film parameters on the spectral and threshold characteristics of the emission shows the importance of the mode confinement and overlap with the modulated area of the film.
The next step has consisted in the realisation of permanent gratings. For this purpose we have implemented an original method of photo-induced patterning of film surface using laser controlled molecular motion in azo-dye aromatic polymers. Irradiation with an interference pattern of films made with such materials leads to surface relief grating formation where the parameters such as the period and the modulation amplitude can be controlled. The film surface structuration is produced by photo-induced mass transport processes that we have investigated in detail. Gratings with periodicities below 200nm using ultraviolet excitation have been produced.
In the last part, the patterning method is applied to two specific cases: realisation of a DFB laser and optimisation of electroluminescent diode emission properties. We demonstrate that diode surface patterning allows enhancing the external efficiency by recovering a part of the light initially guided in the diode structure. The improvement of diode efficiency is followed by modification of the emission spectra as well.
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Submitted on : Friday, January 26, 2007 - 2:21:24 PM
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  • HAL Id : tel-00126698, version 1

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Licinio Rocha. Microstructures électroluminescentes organiques: application à la gestion de l'émission lumineuse.. Physique Atomique [physics.atom-ph]. Université Pierre et Marie Curie - Paris VI, 2002. Français. ⟨tel-00126698⟩

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