Classifications

• • H—ELECTRICITY
  • H10—SEMICONDUCTOR DEVICES; ELECTRIC SOLID-STATE DEVICES NOT OTHERWISE PROVIDED FOR
  • H10K—ORGANIC ELECTRIC SOLID-STATE DEVICES
  • H10K85/00—Organic materials used in the body or electrodes of devices covered by this subclass
  • H10K85/10—Organic polymers or oligomers
  • H10K85/111—Organic polymers or oligomers comprising aromatic, heteroaromatic, or aryl chains, e.g. polyaniline, polyphenylene or polyphenylene vinylene
  • H10K85/113—Heteroaromatic compounds comprising sulfur or selene, e.g. polythiophene
  • H10K85/1135—Polyethylene dioxythiophene [PEDOT]; Derivatives thereof
• • H—ELECTRICITY
  • H10—SEMICONDUCTOR DEVICES; ELECTRIC SOLID-STATE DEVICES NOT OTHERWISE PROVIDED FOR
  • H10K—ORGANIC ELECTRIC SOLID-STATE DEVICES
  • H10K59/00—Integrated devices, or assemblies of multiple devices, comprising at least one organic light-emitting element covered by group H10K50/00
  • H10K59/80—Constructional details
  • H10K59/805—Electrodes
  • H10K59/8051—Anodes
  • H10K59/80516—Anodes combined with auxiliary electrodes, e.g. ITO layer combined with metal lines
• • H—ELECTRICITY
  • H10—SEMICONDUCTOR DEVICES; ELECTRIC SOLID-STATE DEVICES NOT OTHERWISE PROVIDED FOR
  • H10K—ORGANIC ELECTRIC SOLID-STATE DEVICES
  • H10K85/00—Organic materials used in the body or electrodes of devices covered by this subclass
  • H10K85/30—Coordination compounds
  • H10K85/341—Transition metal complexes, e.g. Ru(II)polypyridine complexes
  • H10K85/342—Transition metal complexes, e.g. Ru(II)polypyridine complexes comprising iridium

Definitions

• the invention relates to electroluminescent light emitting devices according to the preamble of claim 1.
• the invention relates to electroluminescent light-emitting devices which contain a conductive polymer and doped organic thin films of oligomers (small dye molecules of about 100 to 1500 amu, also referred to as small molecules) as functional layers.
• oligomers small dye molecules of about 100 to 1500 amu, also referred to as small molecules
• Organic light-emitting diodes represent an important sector of organic semiconductor research.
• the usual layer structure for OLEDs here consists of glass / transparent base contact / organic layer system / metal cover contact. In this structure, the OLED emits through the glass through the highly transparent base contact, which usually represents the anode.
• OLED displays are already available in the automotive and consumer electronics industries. Currently, large-scale lighting facilities represent a much-respected research area. Conceivable here are areas of application, such as billboards on a variety of surfaces and shapes or large-scale room lighting.
• TCO transparent conducting oxides
• ITO indium tin oxide
• ZnO zinc oxide
• a block layer is used on the TCO to separate the subsequent emission layer from the TCO-organic interface.
• An extension of this approach consists on the one hand in the use of a transport or injection layer (TL or IL) of doped organic materials between TCO and block layer. Blochwitz et al.
• PEDOTrPSS is also used for the coating of photo films and also very often in the production of polymer LEDs as anodes.
• the use of PEDOTiPSS in large-area displays / lighting surfaces is problematic because additional metal webs have to be applied to the substrate in order to ensure sufficient power supply to all areas of the display.
• TCOs have a higher conductivity than PEDOT: PSS, for large-area applications (eg large displays, lighting equipment), metal bars must also be applied to TCOs, since their conductivity is still orders of magnitude lower than that of metals.
• TCOs are well established electrode materials for organic light-emitting diodes, they also have detrimental properties for use in OLEDs.
• TCO on flexible substrates, such as PET film has been studied.
• ZnO substrate damage occurs in the ZnO coating, so a thin protective layer of Al 2 O 3 must be applied between the substrate and the ZnO (Pei et al., Thin Solid Films 497, 20-23 (2006) )).
• ITO proves to be too fragile and thus separates as contact material for organic light emitting diodes. on flexible substrates (Paetzold et al., Appl. Phys. Letters 82, 3342, (2003)). Investigations on OLEDs with ITO contacts indicate that indium diffuses from the anodic layer into the adjacent organics, where it can lead to a reduction in the OLED lifetime.
• the organic light-emitting diodes discussed above use a transparent substrate as well as a TCO as electrode (so-called bottom-emission OLED).
• the light emission occurs in this approach through the TCO and the substrate. If, on the other hand, a non-transparent substrate is used, the light emission must be made possible by a final transparent contact (top-emission OLED / Huang et al., Proc. SPIE 5937, 159-164 (2005)).
• Kowalsky et al. (APL 83, 5071 (2003)) demonstrate an approach using a small molecule light emitting diode with a PEDOT: PSS sputtering protective layer.
• the polymer layer represents a protective barrier for the underlying OLED since the sputtering of the terminating ITO contact would directly cause the OLED damage.
• a thin metal layer is normally used as a semitransparent electrode for this type of organic light-emitting diode without PEDOTrPSS is used.
• PEDOT: PSS is applied from an aqueous solution so that Water at the PEDOT small-molecule interface will reduce OLED life.
• the coated substrate is heated with PEDOT prior to the OLED coating ge ⁇ and / or stored in a vacuum, but still a moisture remaining in the can PEDOT OLED boundary surface occur.
• Kim et al. report of so-called "microshorts" (Chem. Mater., 16, 4681-4686 (2004)) in PEDOT: PSS, which should be responsible for leakage currents.
• PEDOT: PSS that the polymerized organic is dissolved in water and filtered before coating the substrate, but there is always the possibility of a residual particle on the PEDOT OLED interface.
• Such polymer particles can be of the order of magnitude of the OLED thickness, which can then lead to a short circuit of hole conductor (PEDOTrPSS) and electron conductor (cathode) of the organic light-emitting diode.
• This function is intended to simplify the manufacturing process and reduce the cost of the light emission device. In this case, a high efficiency and lifetime of the electroluminescent light-emitting device is to be achieved using the functional layer.
• the object is achieved in that a conductive polymer takes over the function of a planar electrode and no further layer of a metal or a transparent conductive oxide is needed.
• a conductive polymer takes over the function of a planar electrode and no further layer of a metal or a transparent conductive oxide is needed.
• the invention enables cost savings due to the use of a low cost, highly conductive polymer instead of a TCO or thin metal film.
• the polymer of the functional layer can be applied to the substrate in air or in a protective gas atmosphere (via spin coating, lolling or printing). After a heating step to remove the residual water from the polymer, the substrate can then be transported to a coating facility. If necessary, the coated substrate may be previously patterned or modified by a non-conductive layer to allow for later driving of the various OLED contacts. In the coating plant then the organic materials are individually or evaporated at the same time. Finally, an electrically conductive cover contact, for example a metal film, is applied, which assumes the function of the counter electrode.
• the object of the invention is achieved by using a combination of a conductive polymer together with a doped layer of oligomers (small molecules) as a functional layer.
• a significant improvement in the tolerance to particles can be achieved by using the doped layer of oligomers. This could be caused by the fact that the doped layer shows ohmic conduction and, unlike the previously used undoped layers in OLED, space-charge-limited currents whose conductivity depends on the thickness with high power.
• the object is achieved by contacting the polymeric electrode layer to a fraction (less than 50%) of its surface with another conductive electrode structure in order to increase the surface conductivity of the overall system.
• this functional layer makes it possible to achieve good results with regard to efficiency and homogeneous luminance in the case of large-area OLEDs, for example with metal webs for improving the current distribution.
• the thickness of the functional layer is chosen so that adverse polymer thicknesses are compensated at the metal edges and the organic light-emitting diode has similar performance, as on a flat polymer substrate. Since these metal lands are larger than the thickness of a conventional organic light-emitting diode (150-200 ⁇ m) for large-area organic light-emitting diodes, it is surprising that the functional layer very well compensates for these surface defects.
• Possible highly conductive polymers which may be used in the sense of the embodiments described herein are e.g. Baytron PH 500 (from HCStarck), or other recently reported highly conductive polymers such as Ormicon's Pani formulations.
• Exemplary embodiment 1 (polymer / doped organic thin layer of oligomers as electrode), see FIG. 1
• Figure 2 illustrates schematically the sample structure in plan view.
• An insulating layer (7) is applied to this substrate so that the counterelectrodes can not come into direct contact with the polymer and cause a short circuit.
• the organic layers (3) and finally counterelectrodes (4) are then applied to the organic layer stack on this substrate.
• As contact for the polymer an additional contact (6) is used.
• the effective luminous area (5) represents the overlap of the counterelectrode (4) with the polymer (2).
• Example sample 1 (according to FIGS. 1a and 2):
• Figure 3 shows the current efficiency and the brightness over the voltage.
• the presented sample on a glass substrate has the following structure:
• MeO-TPD F 4 -TCNQ (4%) 100 nm
• NPB Ir (MDQ) 2 (acac) (10%) 20 nm
• PEDOT Poly (3,4-ethylenedioxythiophene) poly (styrenesulfonate) aqueous dispersion] + 5% DMSO [diethyl sulfoxide]
• PSS Battery-S (Baytron PH 500 [poly (3,4-ethylenedioxythiophene) poly (styrenesulfonate) aqueous dispersion] + 5% DMSO [diethyl sulfoxide]) is placed on the positive pole and the aluminum terminal on the negative pole.
• the electrons and holes meet in the fourth layer (NPB: Ir (MDQ) 2 (acac)) and light is emitted in the red spectral region during the formation / decay of excitons. The light expands in any direction and passes through the transparent organic materials and through the glass from the sample.
• the highly reflective aluminum cathode reflects incoming light and throws it toward the glass substrate, increasing the overall yield of emitted light.
• the doping concentration of cesium in BPhen is in all samples discussed here chosen such that the conductivity of the BPhen: Cs-layer L *, is 5 ⁇ 10 4 S / cm.
• a white organic light emitting device is presented on a • glass substrate.
• various starting materials are combined, so that the components polymerize on the glass substrate (source of the materials, for example, Fa. HCStarck).
• MeO-TPD F 4 -TCNQ (4%) 200 nm 3.
• NPB Ir (MDQ) 2 (acac) (20%) 20 nm
• the organic light emitting diode shines with white light, with color coordinates of (0.30 / 0.29) according to CIE.
• the spectrum is shown in Figure 4.
• the effective luminous surface of the organic light emitting diode in this case shows homogeneous white light.
• the functional layer thus enables a uniform, trouble-free basis for the subsequent emission layers.
• the diode has a homogeneous luminous surface. Since a metal bar was applied at the upper end of the luminous area and the organic light-emitting diode there also shines homogeneously, the functional layer shows its ability to process well even over structured metal bars and their use for large homogenous illuminated areas.
• the thickness of the metal layer in this case was 200 nm.
• Example sample 4 (according to Ib and 2): An organic light-emitting diode is shown on a substrate coated with 100 nm of silver, with the main emission direction facing away from the substrate. This sample uses a reflective substrate on which PEDOT: PSS has been applied. After an insulating layer, the layer system of oligomers is applied to the substrate. Finally, a thin semitransparent metal contact is applied to the sample.
• Figure 6 shows the properties of the organic light emitting diode in terms of brightness and current efficiency as a function of the voltage.
• MeO-TPD F 4 -TCNQ (4%) 80 nm

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• 2006
  • 2006-02-07 DE DE102006006427A patent/DE102006006427A1/de not_active Withdrawn
• 2007
  • 2007-02-06 DE DE112007000905T patent/DE112007000905A5/de not_active Withdrawn
  • 2007-02-06 WO PCT/DE2007/000250 patent/WO2007090390A1/de active Application Filing

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