|Title of Invention||
TRANSPARENT, THERMALLY STABLE LIGHT EMITTING COMPONENT COMPRISING ORGANIC LAYERS
|Abstract||A transparent, thermally stable hght-emitting component having organic layers, in particular an organic light emitting diode, comprising an arrangement of layers including a transparent substrate (1) and two electrodes forming an anode (2; 8a) and a cathode (8; 2a), whereby said anode (2; 8a) is transparent, a hole transport layer (3; 7a), at least one light-emitting layer (5; 5a), and an electron transport layer (3;7a) are formed between said two electrodes, and said hole transport layer (3; 7a) is p-doped with an acceptor-type organic material, characterized in that said cathode (8; 2a) is transparent and said electron transport layer (7;3a) is n-doped with a donor-type organic material, whereby a molecular mass of said acceptor-type organic material and a molecular mass of said donor-type organic material are greater than 200 g/mole.|
THE PATENTS ACT, 1970 (39 of 1970)
COMPLETE SPECIFICATION (See Section 10, rule 13)
TRANSPARENT, THERMALLY STABLE LIGHT-EMITTING COMPONENT COMPRISING ORGANIC LAYERS
NOVALED GMBH of TATZBERG 49, 01307 DRESDEN, GERMANY, GERMAN COMPANY
The following specification particularly describes the nature of the invention and the manner in which it is to be performed : -
Transparent, thermally stable light emitting component with organic layers
The invention relates to a transparent and thermally stable light emitting component with organic layers, especially a transparent organic light emitting diode.
Organic light diodes (OLED) are candidates with rich prospects for the implementation of wide area displays since the demonstration of low working voltages by Tang et al. 1987 [C. W. Tang et al, Appl. Phys. Lett. 51 (12), 913 (1987)]. These consist of a sequence of thin (typically lmn to 1 urn) layers of organic materials, which are preferably vaporized in the vacuum or are obtained from the solution e.g. through centrifugal action. These layers are, therefore, typically transparent by over 80% in visual spectrum range. Otherwise, the OLED would have had lower external light efficiency through re-absorption. The contacting of organic layers with an anode and a cathode is done typically by means of at least one transparent electrode (in the majority of the cases with a transparent oxide, e.g. Indium Tin Oxide ITO) and one metallic contact. Typically this transparent contact (e.g. the ITO) is located directly on the substrate. In case of at least one metallic contact the OLED in totality is not transparent, but reflective or dispersing (through suitably modifying layers, which do not belong to the actual OLED structure). In case of the typical structure with the transparent electrode on the substrate, the OLED emits through the substrate located on its bottom side.
In case of organic light diodes by injecting charge carriers (electrons from one side and holes from the other side) from the contacts in the organic layers located between them tight is produced and emitted by the light diodes as a result of an externally put voltage, formation of excitons (electron hole pairs) in an active zone and the radiating re-combination of these excitons.
The advantage of such components on orgainic base vis-a-vis conventional components on inorganic base (semi conductors like silicium, gallium arsenide) is in
the fact that it is possible to produce very wide surface display elements (picture tubes, screens). The organic base materials are vis-a-vis the inorganic materials relatively economical (lower material and energy consumption). Further, these materials can be applied on flexible substrate because of their low process temperature vis-a-vis inorganic materials, which opens up an entire range of new applications in the display and lighting technology.
The usual arrangement of such components with at least one non-transparent electrode represents a series made of one or more of the following layers:
1. Carrier, substrate,
2. Base electrode, hole injecting (plus pole), typically transparent,
3. Holes injecting layer,
4. Holes transporting layer (HTL),
5. Light emitting layer (EL),
6. Electron transporting layer (ETL),
7. Electron injecting layer,
8 Top electrode, mostly a metal with low work function, electron injecting (minus
9. Encapsulation, to exclude environmental influences.
This is the most common case, mostly some of the layers are omitted (except 2nd, 5th and 8th), or alternatively one layer combines in it several properties. The light emission follows in the described layer sequence through the transparent base electrode and the substrate, whereas the top electrode consists of non-transparent metal layers. Commonly used materials for the transparent base electrode are indium tin oxide (ITO) and related oxide semi-conductor as injection contact for holes (a transparent degenerated semi-conductor). For the electron injection non-precious metals are considered for use, like aluminum (Al), magnesium (Mg), Calcium (Ca) or
a mix layer of Mg and silver (Ag) or such metals in combination with a thin layer of a salt like lithium fluoride (LiF).
Normally these OLEDs are non-transparent. However, there are also applications, for which the transparency is of critical significance. Thus a display element can be produced, which, in switched-off condition, appears transparent, that means the surroundings in the background become apparent, in the switched-on condition, however, allows an information to reach the observer. Here possible applications are for displays in car screens or displays for persons, who should not be restricted through the display in their freedom of movement (e.g. head-on displays for monitoring personnel). Such transparent OLEDs, which represent the basis for transparent displays, are known e. g. from:
1. G. Gu, V. Bulovic, P. E. Burrow, S. R. Ferrest, Appl. Phys. Lett, 68. 2606 (1996)
2. G. Gu, V. Khalfin, S. R. Forrest, Appl. Phys. Lett., 73, 2399 (1998),
3. G. Parthasarathy et al.. Appl. Phys. Lett. 72, 2138 (1997), 4.G. Parthasarathy etal., Adv. Mater. 11,907(1997),
5. G. Gu, G. Parthasarathy et al., S. R. Forrest. Apply. Phys. Lett. 74, 305 (1999). In (1) the transparence is achieved by the way that as basic electrode (that means directly on the substrate) the traditional transparent anode ITO is used. Here it can be found that it is favorable for the operating voltage of the OLED, if the ITO anode is pre-treated in a special method (e.g. ozone sputtering, plasma- incineration), with the aim of increasing the work function of the anode (e.g. C. C. Wu et at, Appl. Phys. Lett. 70, 1348 (1997); G. Gu et al., Appl. Phys. Lett. 73, 2399 (1998)). The work function of ITO can be changed e.g. through ozoning and / or oxygen plasma incineration from approx. 4.2eV to approx. 4.9eV. Then holes can be injected more efficiently from the ITO anode in the hole transport layer. This pretreatment of ITO anode is only possible, if the anode is directly located on the substrate. This structure of the OLED is called non-inverted, the structure of the OLED with the cathode on the substrate as inverted structure. As top electrode in (1) a combination of a thin, semitransparent
layer, non-precious metal (magnesium, stabilized through addition of silver) and a conductive transparent layer of known ITO is used. This combination is therefore necessary, because the work function of the ITO is too high, that efficient electrons can be injected directly in the electron transport layer, and so that OLEDs with low operating voltages could be manufactured. This problem is by-passed by means of very thin magnesium intermediate layer. The emerging component is semitransparent (transparence of the top electrode approx. 50-80%) due to metallic intermediate layer, whereas the transparence of the ITO anode considered as fully transparent is over 90%. In (1) on the metallic intermediate layer one more ITO contact is achieved through sputter process, in order to ensure side-ways conductivity to the connecting contacts of the OLED environment. The ITO sputter process has the consequence that the metallic intermediate layer should not be designed to be thinner than 7.5nm (1), otherwise t he sputter damages at the organic layers below it are too high. Structures of this kind are also described in the following patents: US Patent No. 5,703,436 (S. R. Forrest et al.), submitted on 6.3.1996; US Patent No. 5.757,026 (S.R. Forrest et al.), submitted on 15.4.1996; US Patent No. 5,969,474 (M. Arai), submitted on 24.10.1997. Two OLEDs above each other with cathodes described in (1) have been elaborated in the quotation. Here one green and one red OLED is produced one above the other (stacked OLED). Since both the OLEDs are semi-transparent, then with suitable voltages at three electrodes the emission color can be precisely selected.
Another known implementation of transparent OLEDs provides for an organic intermediate layer for improving the electron injection (quotation 3-5). Here between the light emitting layer (e.g. aluminum tri quinolate, Alq3) and the transparent electrode used as cathode (e.g. ITO) there is an organic intermediate layer. In most of the cases this is copper phthalocyanine (CuPc). This material is actually a hole transport material (more holes as electron move-ability). However, it has an advantage of a high thermal stability. The sputtered top electrode, therefore, cannot cause so much damage to the organic layer below. An advantage and at the same a
disadvantage of this CuPc intermediate layer is the small band gap (gap HOMO -highest occupied molecular orbital to LUMO - lowest unoccupied molecular orbital). The advantage is in the fact that due to low LUMO position relatively light electrons can be injected from LTO, but the absorption due to low band gap in the visual range is high. The layer thickness of CuPc, therefore, must be restricted to below lOnm. Further, the injection of electrons of CuPc in Alq3 or another emission material is difficult, since their LUMO's is at higher level. A further implementation of transparent cathode up on the OLED was suggested by Pioneer (US Patent No. 5.457,565 (T. Namiki), submitted on 18.11.1993). Here in place of CuPc layer a thin layer of an alkaline earth metal oxide (e.g. Li02) is used. This improves the otherwise bad electron injection from the transparent cathode in the light emitting layer. Another implementation of transparent OLED (G. Parthasarathy et al. Apply. Phys. Lett. 76, 2128 (2000), WO Patent 01/67825 Al (G. Parthasarathy), submitted on 7.3.2001. priority date 9.3.2000) provides for an additional electron transport layer (e.g. BCP - Bathocuproine with high electron move-ability) in contact with the transparent cathode (e.g. LTO). Either between the light emitting layer and the (thin From the above work following points become clear:
1. The choice of transparent electrodes is restricted (mainly LTO or similar
2. The work function of the transparent electrodes favor in principle hole injection,
even then, for this a special treatment of anode is necessary, in order to reduce their
3. All developments so far go from there to find out a suitable intermediate layer, which improves the injection of electrons in the organic layers.
For light diodes of inorganic materials it is known that with highly doped border layers thin volume charge zones can be achieved, which also lead with the existing energetic barriers through tunnels to efficient injection of charge carriers. Here doping (as is common in inorganic semi-conductor) means the targeted biasing of conductivity of semiconductor layer through addition of external atoms / molecules. For organic semiconductor often the addition of special emitting molecules to organic layer means doping; a distinction must be made here. The doping of organic materials was described in the US Patent No. 5,093,698 submitted on 12.2.1991. however, this in practical applications leads to problems with the energy balancing of different layers and reduction of efficiency of LEDs with doped layers.
The task of the invention introduced here is to indicate a fully transparent (transmission) organic light emitting diode, which can be operated with reduced operating voltage and which shows a high light emission efficiency. At the same time the protection of all organic layers, especially, however, the light emitting layers against damages is ensured as a result of producing the transparent top contact. The emerging component should be stable (operating temperature range up to 80°C, long time stability).
According to the invention the task in conjunction with the property mentioned in the general term of the transparent, thermally stable, light emitting component with organic layers, especially organic light diode, consisting of an arrangement of layers in a sequence made of a transparent substrate, transparent anode, holes transport layer first this anode, at least one light emitting layer, charge carrier transport layer for electrons and a transparent cathode, is wherein the holes transport layer is p-doped with an acceptor type organic material and the electron transport layer is
r)-doped with a donor type organic material and the molecular masses of dopants are greater than 200g/mol.
Further, according to the invention the task in conjunction with the property mentioned in the general term of the transparent, thermally stable, light emitting component with organic layers, especially organic light diode, consisting of an arrangement of layers in a sequence made of a transparent substrate, transparent cathode, electron transport layer first this cathode, at least one light emitting layer, charge carrier transport layer for holes and a transparent anode, wherein that the holes transport layer is n-doped with an donor type organic material and the holes transport layer is p-doped with an acceptor type organic material and the molecular masses of dopants are greater than 200g/mol
As described in the patent registration DE 101 35 513.0 (Leo et al., submitted on 20.7-2001), one can reverse the layer sequence of the OLED, that means the hole injecting (transparent) contact (anode) to be implemented as top electrode. Usually this leads to that fact that in case inverted organic light diodes the operating voltages are considerably higher than in comparable non-inverted structures. The cause for this is the worse injection from the contacts in the organic layers, because the work function of contacts cannot be optimized with specific target.
In the solution according to the invention the injection of charge carriers from the electrodes in the organic layers (irrespective whether hole or electron transport layers) does not any more depend so heavily on the work function of the electrodes themselves. Thus it is possible, to use on both sides of the OLED component the same electrode type, i.e. for example two same transparent electrodes, e.g. ITO.
The cause for the increase in the conductivity is an increased density of balancing charge carriers in the layer. The transport layer can have here higher layer thickness than what is possible in the non-doped layers (typically 20 to 40nm), without
drastically increasing the operating voltage. Analogue to this is the electron injecting layer (first) of cathode with a donor type molecule (preferable organic molecule or broken parts of it, refer Patent registration DE XXX Ansgars patent) n-doped, which leads to an increase of electron conductivity due to higher intrinsic charge carrier density. Also this layer can be designer thicker in the component than it would be possible with un-doped layers, because this would lead to an increase of operating voltage. Both the layers are thick enough to protect layers below against damages during the production process (sputter) of the transparent electrodes (e.g. ITO).
In the doped charge carrier transport layers (holes or electrons) on the electrodes (anode or cathode) a thin volume charge zone is produced, through which the charge carriers can be efficiently injected. Because of tunnel injection with very thin volume charge zone the injection is not prevented any more even in an energetic high barrier. The charge carrier transport layer is advantageously doped by adding an organic or inorganic substance (dopant). These large molecules set themselves stable in the matrix molecule structure of the charge carrier transport layers. Thereby a high stability is achieved while operating the OLED (no diffusion) and under thermal load.
In the patent registration DE 100 58 578.7 submitted on the 25.11.2000, (refer also X. Zhou et al., Appl. Phys. Lett. 78, 410 (2001)) it is described that organic light diodes with doped transport layers show only efficient light emission, if the doped transport layers are combined in suitable manner with block layers. In an advantageous execution form, therefore, the transparent light emitting diodes also provided with block layers. The block layer is every time between the charge carrier transport layer and a light emitting layer of the component, in which the conversion takes place of electrical energy of charge carriers - by current flow injected through the component -into light. The substances of the block layers are selected as per invention is such a way that with the applied voltage (in the direction of operating voltage) due to its energy level the majority charge carriers (HTL side: holes, ETL side: electrons) are not
prevented heavily at the border layer of doped charge carrier transport layer / block layer (low barrier), but the minority charge carriers are efficiently prevented at the border layer light emitting layer / block layer (high barrier). Further the level of barriers for injection of charge carriers from the block layer in the emitting layer should be so low that the conversion of a charge carrier pair at the border surface in to an exciton in the emitting layer is energy-wise advantageous. This prevents formation of exciplex at the border areas of the light emitting layer, which reduces the efficiency of light emission. Since the charge carrier transport layers preferably show a high band gap, the block layers can be selected very thin, because despite this no tunneling of charge carriers from the light emitting layer in energy statuses in the charge carrier transport layers possible. This allows, to achieve - despite block layers - a low operating voltage.
An advantageous design of a structure of an invention based transparent OLED contains following layers (non-inverted structure):
1. Carrier, substrate
2. Transparent electrode, e.g. TTO, holes injecting (anode=plus pole),
3. p-doped. holes injecting and transporting layer,
4. thin hole side block layer made of a material with band positions matching with those band positions of the surrounding layers,
5. light emitting layer (perhaps doped with emitter dye),
6. thin electron side block layer made of a material, whose band positions match with the band positions of the surrounding layers,
7. n-doped electrons injecting and transporting layer,
8. transparent electrode, electron injecting (cathode=minus pole),
9. encapsulation, for exclusion of environmental impacts.
An advantageous design of a structure of an invention based transparent OLED contains following layers (inverted structure):
1 Carrier, substrate
2a Transparent electrode, e.g. ITO. electron injecting (cathode=minus pole),
3a n-doped, electron injecting and transporting layer,
4a thin electron side block layer made of a material with band positions matching
with those band positions of the surrounding layers,
5a light emitting layer (perhaps doped with emitter dye),
6a thin hole side block layer made of a material, whose band positions match with the
band positions of the surrounding layers,
7a p-doped holes injecting and transporting layer,
8a transparent electrode, electron injecting (anode=plus pole), e.g. ITO
9 encapsulation, for exclusion of environmental impacts.
It is also in the sense of the invention, if only one block layer finds application, because the band positions of injecting and transporting layer and the light emitting layer already match with each other on one side. Further, the functions of charge carrier injection and the charge carrier transport in the layers 3 and 7 are divided in to several layers, of which at least one (and i.e. the one of the electrodes) is doped. If the doped layer is not located immediately at the respective electrode, then all layers between the doped layer and the respective electrode must be so thin, that these can tunneled through efficiently by charge carriers ( The invention is explained with more details in the following on the basis of execution examples. In the drawings following has been represented:
Fig.l An energy diagram of a transparent OLED in the existing common execution form (without doping, the numbers refer to the above described non- inverted layer structure of the OLED as per claim 1). At the top the position of the energy levels (HOMO and LUMO) without external voltage are described (it can be seen that both the electrodes possess equal work function), at the bottom with connected external voltage. For the purpose of easy representation also the block layers 4 and 6 have been depicted along.
Fig.2 An energy diagram of a transparent OLED with doped charge carrier transport layers and matching block layers (one must observe here the band bending first to the contact layers, here in both the cases UO). The numbers refer to both the above described executions. At the top the structure of the component has been shown, which due to its transparency emits light in both the directions, below the band structure.
Fig.3 Light emitting density - voltage characteristic curve of the execution example shown below, the typical monitor - light emitting density of 100cd/m2 is achieved with 4 V itself. The efficiency is 2cd/A. However, here as anode material - due to technical reasons - no transparent contact (e.g. ITO) is used, but it is simulated by means of a semi-transparent (50%) gold contact. It is a semi-transparent OLED.
In the execution form displayed in Fig.l no volume charge zone occurs at the contacts. This execution design asks for a low energy barrier for the charge carrier injection. This can - under the circumstances - not be achieved or only with great difficulty with available materials (refer technology status above). The injection of charge carriers from the contacts is, therefore, not so effective. The OLED shows an increased operating voltage.
According to the invention the disadvantage of the existing structures is avoided through transparent OLEDs with doped injection and transport layers, if necessary, in conjunction with block layers. Fig. 2 shows a suitable arrangement. Here the charge carrier injecting and charge carrier conducting layers 3 and 7 are doped, so that at the border layers to the contacts 2 and 8 volume charge zones are formed. Condition is that the doping is high enough, so that these volume charge zones can be easily through tunneled. That such doping is possible was already shown at least for the p-doping of holes transport layer in the literature for non-transparent light diodes (X.Q.Zhou et al., Appl. Phys. Lett. 78, 410 (2001); J. Blochwitz et al., Organic Electroics 2/97 (2001)).
This arrangement characterizes itself through following preferences:
• An excellent injection of charge carriers from the electrodes in the doped charge carrier transport layers.
• The independence from the detailed preparation of the charge carrier injecting materials 2 and 8.
• The possibility of selecting also materials with comparatively high barriers for the charge carrier injection for the electrodes 2 and 8, e.g. in both the cases the same material, e.g. no.
A preferred execution example is given below. However, in this example no n- doping of electron transport layer with stable large organic dopant occurs. As an example for the effectiveness of the design of transparent OLED with doped organic transport layers, an execution with the non-stable n-doping of a typical electron transport material (Bphen bathophenathroline) with Li is shown (Patent US 6,013,384 (J. Kido et at), submitted on 22.1.1998; J. Kido et al., Appl. Phys. Lett. 73, 2866 (1998)). As already described in the state-of-the-art technology this approx. 1:1 mixture of Li and Bphen can demonstrate the effectiveness of the doping. However, this layer is not stable from thermal and operational point of view. Since in this doping very high dopant
concentrations can occur, it must be assumed, that the mechanism of doping is different. In the doping with organic molecules and doping ratios between 1:10 and 1:10000 it is to be assumed that the dopant the dopant does not have major influence on the structure of the charge carrier transport layer. In the 1:1 addition of doping metals, e. g. Li cannot be assumed.
The OLED shows the following layer structure (inverted structure):
la: Substrate, e.g. glass.
2a: Cathode: 1TO as bought, not treated,
3a: n-doped electron transporting layer: 20nm Bphen: Li 1:1 molecular mixing ratio
4a: Electron side block layer lOrtm Bphen,
5a: Electron luminating layer: 20nm Alq3, can be mixed with emitter dopant, for
increasing the internal conversion quantum efficiency of the light generation,
6a; Hole side block layer: 5nm Triphenyle Diamine (TPD),
7a: p-doped holes transporting layer: lOOnm Starburst m-MTDATA 50:1 doped with
F4-TCNQ dopant (thermally stable up to about 80oC),
8a: transparent electrode (anode): Indium Tin oxide (JTO).
The mixed layers 3 and 7 are produced in a vaporizing process in the vacuum in mix evaporation. In principle such layers can also be produced through other processes, like e.g. vaporizing of substances one above other followed by possible temperature controlled diffusion of substances in each other; or through other application (e.g. with spinning effect) of already mixed substances in or outside the vacuum. The block layers 3 and 6 were also vaporized in the vacuum, however, these can also be produced in different way, e.g. through spinning effect within or without the vacuum.
In Fig. 3 the light density - voltage characteristic curve of a semi-transparent OLED has been represented. For the test purposes a semi-transparent gold contact was used as anode (50% transmission). An operating voltage of 4V is needed for a light density
of 100cd/m2. This is one of the smallest implemented operating voltages for transparent OLEDs, especially with inverted layer structure. This OLED demonstrates the implement-ability of the design introduced here. Because of semi-transparent top electrode the external current efficiency achieves only a value of about 2cd/A and not 5cd/A, which is expected maximum for OLEDs with pure Alq3 as emitter layer.
The invention based application of doped layers allows nearly the same low operating voltages and high efficiencies in a transparent structure to be achieved like these occur in a traditional structure with one sided emission through the substrate. This as described is due to the efficient charge carrier injection, which - thanks to doping - are relatively independent of the exact work function of the transparent contact materials. Thus the same electrode materials can be used (or transparent electrode materials which in their work function) as electron and hole injecting contact.
From the execution examples it is apparent for the technical expert, that many modifications and variations of the introduced invention are possible, which are in the sense of the invention. For example, other transparent contacts can be used as ITO as anode materials (e.g. like in H. Kirn et al, Appl. Phys. Lett. 76, 259 (2000); H. Kirn et al., Appl. Phys. Lett. 78,1050 (2001)). Further, it is in conformity with the invention to put together the transparent electrodes with a sufficiently thin intermediate layer of a non-transparent metal (e.g. silver or gold) and a thick layer of transparent conductive material. The thickness of the intermediate layer must be and can be (since due to thick doped charge carrier transport layers no damages to light emitting layers are expected during sputtering) so thin, that the entire component is still transparent in the above sense (transparence in the entire visible spectrum range > 75%). Another execution conforming to the invention is in the fact that for the doped electron transport layer a material is used, whose LUMO level is too deep (in the sense of Fig. 1 and 2: layer 7 or 3a) so that still efficient electrons can be injected in the block layer and the light emitting layer (6 or 4a and 5 or 5a) (that means greater barrier than
depicted in Fig.2). Then between the n-type doped election transport layer (7 or 3a) and the block layer (6 or 4a) or the light emitting layer (5 or 5a) a very thin ( List of reference symbols:
2,2a Anode or Cathode
3,3a Holes or electron transport layer (doped)
4, 4a Holes side and electron side thin block layer
5,5a Light emitting layer
6,6a Electron or hole side block layer
75 7a Hole or electron transport layer (doped)
89 8a Anode or cathode
1. A transparent, thermally stable hght-emitting component having organic layers, in particular an organic light emitting diode, comprising an arrangement of layers including a transparent substrate (1) and two electrodes forming an anode (2; 8a) and a cathode (8; 2a), whereby said anode (2; 8a) is transparent, a hole transport layer (3; 7a), at least one light-emitting layer (5; 5a), and an electron transport layer (3;7a) are formed between said two electrodes, and said hole transport layer (3; 7a) is p-doped with an acceptor-type organic material, characterized in that said cathode (8; 2a) is transparent and said electron transport layer (7;3a) is n-doped with a donor-type organic material, whereby a molecular mass of said acceptor-type organic material and a molecular mass of said donor-type organic material are greater than 200 g/mole.
2. A light-emitting component according to claim l,characterized in that a hole-side blocking layer (4; 6a) is provided between said doped hole transport layer (3; 7a) and said light-emitting layer (5; 5a),
3. A light-emitting component according to claim 1 or 2, characterized in that an electron-side blocking layer (6; 4a) is provided between said doped electron transport layer (7; 3a) and said light-emitting layer (5; 5a).
4. A hght-emitting component according to one of the claims 1 to 3, characterized in that said two transparent electrodes are of the same electrode type.
5. A light-emitting component according to one of the claims 1 to 4, characterized in that said two transparent electrodes consist of indium tin oxide (ITO).
6. A light-emitting component according to one of the claims 1 to 5, characterized in that said two transparent electrodes consist of a transparent material similar to ITO, namely of another degenerate oxide semiconductor.
7. A light-emitting component according to one of the claims 1 to 6, characterized in that said two transparent electrodes consist of different transparent contact materials.
8. A Hght-emitting component according to one of the claims 1 to 7, characterized in that a thin ( 9. A light-emitting component according to one of the claims 1 to 8, characterized in that said light-emitting layer (5; 5a) is a mixed layer of several materials.
10. A light-emitting component according to one of the claims 1 to 9, characterized in that said hole transport layer (3; 7a) consists of an organic main substance and said acceptor-type organic material.
11. A light-emitting component according to one of the claims 1 to 10, characterized in that said electron transporting layer (7; 3a) consists of a mixture of an organic main substance and said donor-type organic material.
12. A light-emitting component according to one of the claims 1 to 11, characterized in that a top situated of said two transparent electrodes (8; 8a) is provided with a transparent protective layer (9).
13. A light-emitting component according to one of the claims 1 to 12, characterized in that said top situated transparent electrode (8; 8a) is provided with a very thin ( 14. A light-emitting component according to one of the claims 1 to 13, characterized in that a bottom situated of said two transparent electrodes (2; 2a) is provided with a very thin ( 15. A hght-emitting component according to one of the claims 1 to 14, characterized in that an arrangement of said p-doped hole transport layer (3; 7a) and said transparent anode (2; 8a) is formed repeatedly.
16. A light-emitting component according to one of the claims 1 to 15, characterized in that an arrangement of said n-doped electron transport layer (7; 3a) and said transparent cathode (8; 2a) is formed repeatedly.
17. A light-emitting component according to one of the claims 1 to 16, characterized in that a thin ( 18. A light-emitting component according to one of the claims 1 to 17, characterized in that the molar concentration of the admixture in said hole transport layer (3; 7a) and/or in said electron transport layer (7; 3a) lies in the range of 1 : 100,000 to 1 : 10, calculated on the ratio of doping molecules to main-substance molecules.
19. A light-emitting component according to one of the claims 1 to 18, characterized in that a layer thickness of each of said hole transport layer (3; 7a), said electron transport layer (7; 3a), said at least one light- emitting layer (5; 5a), said hole-side blocking layer (4; 6a), and said electron-side blocking layer (6; 4a) lies in the range of 0.1 nm to 50 |um.
Dated this 19th day of April 2004.
ASEAN SAARC PATENT & TRADE MARK SERVICES AGENT FOR NOVALED AG
|Indian Patent Application Number||233/MUMNP/2004|
|PG Journal Number||41/2008|
|Date of Filing||19-Apr-2004|
|Name of Patentee||NOVALED AG|
|Applicant Address||TATZBERG 49, 01307 DRESDEN,|
|PCT International Classification Number||H01L 51/20|
|PCT International Application Number||PCT/DE03/01021|
|PCT International Filing date||2003-03-27|