Organic-based optoelectronic components, for example organic light-emitting diodes (OLEDs), are increasingly finding widespread use in general lighting, for example as an areal light source.
An organic optoelectronic component, for example an OLED—illustrated in FIG. 5—may include an anode 510 and a cathode 514 with an organic functional layer in between, on a substrate 502.
The electrodes 512, 514 are separated electrically from one another by means of electrically insulating structures 504. The electrodes 510, 514 can conventionally form electrical contacts in the edge regions of the optoelectronic component by means of contact strips 506 and contact pads 516.
The organic functional layer system 512 may include one or more emitter layer(s) in which electromagnetic radiation is generated, one or more charge carrier pair generation layer structure(s) each composed of two or more charge carrier pair generation layers (“charge generating layers”, CGL) for charge carrier pair generation, and one or more electron blocker layer(s), also called hole transport layer(s) (HTL), and one or more hole blocker layer(s), also referred to as electron transport layer(s) (ETL), in order to direct the current flow.
For protection from water and oxygen, the optoelectronic component is conventionally surrounded by a hermetic encapsulation which is impervious to water and oxygen. The encapsulation conventionally includes a thin-film encapsulation 508 and a cover glass 524 laminated on by means of adhesive 522. In addition, a conventional encapsulation may also take the form of a cavity glass encapsulation (cavity encapsulation).
Areal light sources, for example OLEDs, are very prone to defects such as particles 518. The particles 518 may have a measurement in the order of magnitude equal to or greater than the layer thicknesses of the layers of the optoelectronic component. The particles 518 may also lie atop the thin-film encapsulation 508 and be pushed mechanically through the layers of the optoelectronic component. Particles 518 may very frequently lead to a short circuit in the operation of the optoelectronic component, where mechanical stress on the particle by means of stress on the cover glass 524 causes the cathode 514 to form a contact with the anode 510. This can result in spontaneous failure of the lighting means for an indeterminate period of time.
In a conventional method of reducing particle contamination, organic light-emitting diodes are manufactured in cleanrooms with the minimum possible particle contamination, particularly in the case of manufacture of the substrate 502 and the encapsulation 508, 522, 524 of the organic light-emitting diodes. The cleanroom class, for example according to ISO 14644-1, may in principle not be good enough for this purpose, for example a lower particle concentration than in ISO 1 according to ISO 14644-1. Thus, as a result of particle contamination in the production of optoelectronic components, an indeterminate yield loss is to be expected.
In a conventional method of reducing particle contamination, the light-emitting area is discretized and an anti-short circuit means is integrated into the light-emitting area.
In a conventional method of reducing particle contamination, a particle screening method (particle grid method) is used in a cleanroom to detect particle contamination in the production of light-emitting diodes. However, this method is costly and inconvenient and merely reduces the yield loss in manufacturing.
In a conventional method of reducing particle contamination, the components are tested in electrooptical particle screening methods. However, components affected cannot be eliminated 100% from the yield, typically only to an extent of 98-99%.
In a conventional method of reducing particle contamination, the OLEDs are encapsulated with a cavity glass, with application of a layer sequence system composed of hard and soft layers to the organic functional layer stack in the cavity, in order to bind particles. In addition, thick thin-film encapsulations are used, having a thickness of 3 μm to 5 μm. In addition, insulation oils, pastes or adhesives are applied as buffers to the organic functional layer stack.
In addition, it is known that capacitor oils in capacitors lead to self-healing processes at temperatures around 1000 K.
Additionally known are solid-state oxidizing agents for reduction of the short-circuit risk in the event of particle contamination. The possible materials are restricted to particular materials which are nonconductive and nontoxic as reactant/product before/after the process. For efficacy, a certain minimum temperature at the potential short-circuit is required, in order to initiate the reaction.