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Multilayer OLEDs (multilayer + oled)

Distribution by Scientific Domains

Polymers and Materials Science	100%

Selected Abstracts

Organic LEDs: The Simple Way to Solution-Processed Multilayer OLEDs , Layered Block-Copolymer Networks by Living Cationic Polymerization (Adv. Mater.

ADVANCED MATERIALS, Issue 8 2009
8/2009)
A novel strategy for simple, intelligent, and cost-effective fabrication of multilayer OLEDs by solution-processing is demonstrated by Klaus Meerholz and co-workers on p. 879. The cover shows the self-smoothing of thin polymer films using this method, termed "layer-by-layer crosslinking" (LBLX). LBLX enables the crosslinking and smoothing of several polymer layers on top of each other simply by using a heat and wash procedure. [source]

The Simple Way to Solution-Processed Multilayer OLEDs , Layered Block-Copolymer Networks by Living Cationic Polymerization

ADVANCED MATERIALS, Issue 8 2009
Anne Köhnen
Solution-processed multilayered OLEDs are fabricated through a conceptually novel, simple, intelligent, and cost-effective strategy, namely "layer-by-layer cross-linking" (LBLX). It enables the use of a wide range of conventional and low-priced wet deposition techniques (e.g., all printing techniques), and is based on "PEDOT-initiated cross-linking" of oxetane-functionalized polymers, which resembles the "grafting-from" approach. [source]

Multifunctional Crosslinkable Iridium Complexes as Hole Transporting/Electron Blocking and Emitting Materials for Solution-Processed Multilayer Organic Light-Emitting Diodes

ADVANCED FUNCTIONAL MATERIALS, Issue 7 2009
Biwu Ma
Abstract Here, a new series of crosslinkable heteroleptic iridium (III) complexes for use in solution processed phosphorescent organic light emitting diodes (OLEDs) is reported. These iridium compounds have the general formula of (PPZ-VB)2Ir(C,N), where PPZ-VB is phenylpyrazole (PPZ) vinyl benzyl (VB) ether; and the C,N ligands represent a family of four different cyclometallating ligands including 1-phenylpyrazolyl (PPZ) (1), 2-(4,6-difluorophenyl)pyridyl (DFPPY) (2), 2-(p-tolyl)pyridyl (TPY) (3), and 2-phenylquinolyl (PQ) (4). With the incorporation of two crosslinkable VB ether groups, these compounds can be fully crosslinked after heating at 180,°C for 30,min. The crosslinked films exhibit excellent solvent resistance and film smoothness which enables fabrication of high-performance multilayer OLEDs by sequential solution processing of multiple layers. Furthermore, the photophysical properties of these compounds can be easily controlled by simply changing the cyclometallating C,N ligand in order to tune the triplet energy within the range of 3.0,2.2,eV. This diversity makes these materials not only suitable for use in hole transporting and electron blocking but also as emissive layers of several colors. Therefore, these compounds are applied as effective materials for all-solution processed OLEDs with (PPZ-VB)2IrPPZ (1) acting as hole transporting and electron blocking layer and host material, as well as three other compounds, (PPZ-VB)2IrDFPPY (2), (PPZ-VB)2IrTPY(3), and (PPZ-VB)2IrPQ(4), used as crosslinkable phosphorescent emitters. [source]

Modifying the Output Characteristics of an Organic Light-Emitting Device by Refractive-Index Modulation,

ADVANCED FUNCTIONAL MATERIALS, Issue 18 2006
T. Höfler
Abstract In order to modify the output characteristics of organic light-emitting devices (OLEDs), the optical properties of an active layer within the device are patterned without introducing any thickness modulation. For this purpose a new conjugated copolymer, which serves as a hole-transporting material and at the same time can be index patterned using UV techniques, is synthesized. Poly(VC- co -VBT) (VC: N -vinylcarbazole; VBT: 4-vinylbenzyl thiocyanate) is prepared by free-radical copolymerization of VC and VBT. The material contains photoreactive thiocyanate groups that enable altering of the material's refractive index under UV illumination. This copolymer is employed as a patternable hole-transporting layer in multilayer OLEDs. Refractive-index gratings in poly(VC- co -VBT) are inscribed using a holographic setup based upon a Lloyd mirror configuration. The fourth harmonic of a Nd:YAG (YAG: yttrium aluminum garnet) laser (266,nm) serves as the UV source. In this way 1D photonic structures are integrated in an OLED containing AlQ3 (tris(8-hydroxyquinoline) aluminum) as the emitting species. It is assured that only a periodical change of the refractive index (,n,=,0.006 at ,,=,540,nm) is generated in the active material but no surface-relief gratings are generated. The patterned devices show more forward-directed out-coupling behavior than unstructured devices (increase in luminosity by a factor of five for a perpendicular viewing direction). This effect is most likely due to Bragg scattering. For these multilayer structures, optimum outcoupling was observed for grating periods ,,,,390,nm. [source]