Reference : OLED Light extraction improvement with surface nano-micro texturation based on speckle l...
Scientific congresses and symposiums : Paper published in a book
Physical, chemical, mathematical & earth Sciences : Physics
http://hdl.handle.net/2268/117700
OLED Light extraction improvement with surface nano-micro texturation based on speckle lithography.
English
Loicq, Jerôme mailto [Université de Liège - ULg > > CSL (Centre Spatial de Liège) >]
Fleury-Frenette, Karl mailto [Université de Liège - ULg > > CSL (Centre Spatial de Liège) >]
Viville, Pascal [Materia Nova ASBL > > > >]
Lazzaroni, Roberto [Material Nova ASBL - UMH > > > >]
Kanaan, Hani [Commissariat à l'Energie Atomique (Saclay) - CEA > > > >]
Guaino, Philippe [CRM group > > > >]
2012
Physiscs and Optics of OLEDs
No
No
International
SPIE Photonics Europe 2012
16/04/2012 to 19/04/2012
[en] OLED ; Outcoupling ; Laser speckle
[en] Part of the light rays generated within a luminescent medium with a higher refractive index than that of the exit medium, typically air, undergo total internal reflection phenomenon (TIR); these rays will be trapped and guided into the emissive material and will not be extracted out of an OLED device for instance. Trapped light is reabsorbed and eventually converted into heat that will be detrimental to the device performance and lifetime. The amount of trapped energy is highly dependent on the values of the refractive indices involved in the multilayer stack constituting the light emitting device. The amount of trapped energy can be extensive and can even reach as much as 75% in certain cases. Solutions to improve the outcoupling efficiency are therefore attractive. In this paper we propose to use laser speckle to produce a random surface with controlled parameters to enhance the OLED outcoupling. A laser speckle pattern is transferred onto a photoresist which will be subsequently converted into a surface relief profile. The optical setup parameters drive the properties of such surface and thus the outcoupling properties. The resulting surface has a quasi-random shape which could be assimilated to a corrugated surface. We will show that these typical surfaces exhibit light extraction enhancement properties. The generated pattern is then transferred onto the exit interfaces of the emitting device. An extraction improvement close to a factor 3 is measured. We finally discuss a practical case for which the laser speckle shape is applied to texture the surface of encapsulating cover glasses in a top-emitting OLED on steel substrates.
Region Wallonne
Researchers ; Professionals ; Students ; General public ; Others
http://hdl.handle.net/2268/117700

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