WO2008023008A1

WO2008023008A1 - Planar luminous element and use of the planar luminous element

Info

Publication number: WO2008023008A1
Application number: PCT/EP2007/058660
Authority: WO
Inventors: Christoph Gärditz; Stefan Seidel
Original assignee: Osram Opto Semiconductors Gmbh
Priority date: 2006-08-24
Filing date: 2007-08-21
Publication date: 2008-02-28
Also published as: DE102006039789A1

Abstract

The invention relates to a planar luminous element, wherein the luminous element is constructed from at least one organic light-emitting diode, wherein a plurality of points of the anode (3) are at least approximately at the same potential, wherein the organic light-emitting diode comprises a cathode (1) and an anode (3), and at least one organic layer (2) between the cathode (1) and the anode (3), wherein at least one of the at least one organic layers (2) emits light when an electrical voltage is applied to the cathode (1) and the anode (2), wherein, for making electrical contact with the plurality of points (7) of the anode (3), no material of the cathode (1) and of the organic layer (2) is present at said points (7) such that contact can be made with the corresponding points (7) of the anode (3) from the rear side of the planar luminous element. In addition, the invention relates to the use of such a luminous element for the illumination of road signs and/or signals.

Description

description

Flat luminous element and use of the planar luminous element

The present invention relates to a planar luminous element according to the preamble of patent claim 1 and the Verwen ^¬ tion of such a planar luminous element according to claim 3.

Applicants are aware of attempts to use organic light emitting diodes (OLEDs) in the field of lighting and signaling / signage. Such light-emitting elements are composed of Wenig ^¬ least an organic light-emitting diode, wherein a plurality of points of the anode are at least approximately at the same potential, wherein the organic light emitting diode from a leitfähi ^¬ gen cathode and anode is made and at least one organic ^¬ rule layer between the cathode and the anode of which at least one layer emits light when a voltage is applied to the cathode and the anode.

A particular advantage results from the fact that the light ^¬ de is thin, can be carried out over a large area, only a small voltage needed and potentially can be flexibly designed.

However, due to the materials used and / or the small layer thicknesses, the electrodes of an OLED have a relatively high resistance. This applies in particular to the material indium tin oxide (ITO), which is frequently used for the anode. Be ^¬ Sonder at high current densities results in a voltage drop, which leads to significant inhomogeneities in luminance due to this Wi ^¬ derstands emitting large areas. This is problematic, especially for lighting applications requiring large and homogenous illuminated surfaces.

This could be solved for example by means of new, higher conductive materials with similar properties as the previous anodes. Such materials are currently not known. At present, additional conductive auxiliary structures (eg metal strips) or layers are applied to the anode in order to increase the conductivity and thus to improve the homogeneity of the current and consequently of the luminance.

The object of the present invention is to improve the homogeneity of the luminance of such luminous elements.

This object is achieved according to the present invention according to claim 1, in that for the electrical contacting of the points of the anode at several points no material of the cathode and the organic layer is present, so that the corresponding points of the anode from the back of the planar lighting element are contactable.

It can be advantageously avoided by this embodiment that metallic compounds are mounted on the visible side of the light ^¬ element to apply a voltage to the corre sponding ^¬ points. In particular, there is also the possibility of the center of the area to see through such points vorzu ^¬ without cover this area in part.

The preparation of such planar light-emitting elements can be carried out by means of shadow masks or by means of a Materialab ^¬ Trages the cathode and an organic layer at least Zvi ^¬ rule in a subsequent manufacturing step. In general, this production can be summarized by the term "suitable structuring measures." These can also be, for example, in lithographic steps, printing or other production processes.

As a particularly advantageous over the prior art, it ^{¬ it} shows that the manufacturing step for applying the metallic contact tracks can be omitted. This step had to be done in a vacuum and brought problems Impurities and associated functional problems with it.

In the embodiment according to claim 2, the cathode and the organic layer at least over the entire surface are produced in a first step, followed removal of the material of the cathode and the material of one organic layer occurs at the entspre ^¬ sponding points at least.

This removal of the layers can take place, for example, by means of microstructuring, laser radiation, by mechanical measures or also chemically.

This approach turns out to manufacture than be ^¬ Sonder's easy to carry out.

Claim 3 relates to the use of a flat Leuchtele ^¬ mentes according to claim 1 or 2 for the illumination of street signs and / or signals.

Here, the uniform illumination also RESIZE ^¬ ßerer surfaces turns at relatively low energy input to be particularly advantageous.

The electrical contact can be done by means of spring contacts. The holes at the corresponding points in the cathode as well as the at least one organic layer can be made comparatively small, so that they are no longer perceptible at a comparatively small distance from the luminous element.

In contrast to the prior art, in the present invention the anode is not supplied with power to the side by way of broad metallizations but by many point contact points which are distributed over the entire surface. This will be explained in the following drawing. The contact points can be produced, for example, according to the following procedure. The OLED consists for example of the layer sequence glass substrate / ITO anode / organic layers / metal cathode. Other anode materials and layer sequences as well as substrate materials are also possible. By means of a fine laser beam of suitable wavelength or by means of microstructuring, the organic layers and the cathode of the OLED are removed. What remains is the bare anode at this point is freely accessible (by the non-emissive back of OLED) and from the cathode iso ^¬ lines. By suitable contacting (for example by spring contact pins) can be fed into the anode at such a location power.

At the same time the cathode from the back ENTRANCE ^¬ Lich remains. Through many such contact points, the OLED can be powered. The density and position of the contacts is adjusted to the required current density and their required homogeneity. They can be made so small that they are no longer noticeable on the front of the OLED from a short distance.

According to the present invention advantageously provides additional metal structures or layers may be omitted, which are mounted on or un- ter the anode to treble the conductivity to he ^¬. This eliminates a laborious process advantageous ^¬ step which usually has to take place in a vacuum. Any Me ^¬ tallstruktur on / under the anode reduces the emitting area of the OLED. This is the case to a much lesser extent in the case of the present invention, since the contacts are punctiform in nature and do not represent lines.

Also, no engagement will take place in the area of the electrically active layers in the processing of the OELD, which play as examples the burden of particles / residue verrin ^¬ siege and thus positively affects the reliability, performance and visual appearance of the OLED. The ablation of the OLED layers down to the anode can be done quickly and automatically, and thus cost-effectively, for example, with an established laser process.

The density and position of the contact points can be varied as needed.

Since by the present invention, the lateral feedline ^¬ tracks to the anode on the substrate dispensed with, the filling factor is increased on the substrate. With the same size, a larger area can be used to generate light.

In a construction comprising a plurality of light-emitting diodes, the individual tiles can be packed closer together with less or no gap. As a result, for example, the homogeneity of a large area, which consists of individual elements, significantly improved.

An embodiment of the invention is shown in the drawing. The two figures show:

Fig. 1: a section of a flat luminous element in a lateral section and

Fig. 2: the planar luminous element in plan view.

1 shows a planar light-emitting element in a seitli ^¬ chen section. It is the substrate 4 to see as a carrier of the flat luminous element.

Attached thereto is the anode 3, which may consist of indium tin oxide (ITO), for example. Between this anode 3 and the metallic cathode 1, an organic layer 2 is introduced.

It can also be seen that 2 holes are introduced in the cathode 1 and in the organic layer. In the Figure 1 it can be seen that are inserted through these holes contact pins 6, by means of which the anode 3 is connected to a tensioning ^¬ voltage source. It can also be seen that the cathode 1 is also connected to the voltage source.

The anode 3 is therefore contacted by the rear side of the planar luminous element.

The reference numeral 5, the light is emitted, which is emitted from the flat luminous element.

If the cathode 1 consists of individual surface elements, a contact with the voltage source must be present for each of these surface elements. If the cathode 1 is formed as a continuous surface with the holes, it is sufficient in a metallic cathode u.U. merely to make contact of the cathode with the voltage source.

FIG. 2 shows a part of the planar luminous element in plan view. There are the holes 7 to see, through which the

Contacting the anode takes place. Likewise, the emitting surface 8 can be seen.

Claims

claims

1. The sheet light emitting element, the light-emitting element made of soft ^¬ an organic light emitting diode is constructed nigstens, wherein a plurality of points of the anode (3) at least approximately lie on demsel ^¬ ben potential, wherein the organic light emitting diode composed of a cathode (1) and an anode (3 ) is made as well as Wenig ^¬ least one organic layer (2) between the cathode (1) and the anode (3), wherein at least one of the at least one organic layer (2) to the cathode (upon application of a voltage 1) and the anode ( 3) emitted light, characterized in that for electrical contacting of the plurality of points (7) of the anode (3) at these points (7) no material of the cathode (1) and the at least one organic layer (2) is present, so that the corresponding points (7) of the anode (3) can be contacted from the rear side of the planar luminous element.

2. Luminous element according to claim 1, characterized in that the cathode (1) and the we ^¬ least one organic layer (2) are produced over the entire surface in a first step, wherein subsequently at the corresponding points (7) removal of the material of the cathode (1) and the material of the at least one organic layer (2).

3. Use of a flat luminous element according to claim 1 or 2 for the illumination of street signs and / or signals.