KR101706680B1 - Organic light-emitting component - Google Patents

Abstract

The present invention relates to an electrode (1); A counter electrode (2); And a stack (3) of organic layers having at least two light emitting units (4, 5) and at least one connecting unit (6) each having a light emitting layer (8; 10) As the first connecting unit having the n-dopant layer made of the electrically p-doped hole transporting layer and the organic n-doping material, the n-dopant layer 20 is formed adjacent to the light emitting layer 8 Wherein the organic n-doping material is a first connecting unit having a HOMO level greater than -3.3 eV; And a p-dopant layer (21) made from an organic p-doped material, wherein the p-dopant layer (21) is adjacent to the luminescent layer (10) And the organic p-doped material is formed according to one of the second connection units having a LUMO level lower than -4.5 eV.

Description

[0001] ORGANIC LIGHT-EMITTING COMPONENT [0002]

The present invention relates to an organic light emitting device.

These devices typically include a stack of organic layers disposed between the electrodes and the opposing electrodes, as well as electrodes and counter electrodes. By applying a voltage to both electrodes in the stack, the organic layer is in the form of electrons and holes that recombine in the light- Free charge carrier can be produced. The organic light emitting device is preferably produced as an organic light emitting diode (OLED).

A known embodiment of the organic light emitting element has a configuration in which a plurality of so-called light emitting units are arranged in a stack and a so-called connecting unit is arranged between adjacent light emitting units. A simple embodiment of such a device is also referred to as a tandem component wherein precisely two light emitting units are arranged between the electrodes and the opposing electrodes adjacent to the two electrodes and exactly one connection unit between the two light emitting units Respectively. The connection unit is formed of an electrically n-doped electron transport layer (ETL) and an electrically p-doped hole transport layer (HTL). The intermediate layer of organic material may be disposed between two electrically-doped transport layers.

The light-emitting unit has a charge-carrier transporting layer and at least one light-emitting layer (EML). With the aid of the charge carrier transport layer, the charge carriers, i.e., holes and electrons, formed in the stack of organic layers when a voltage is applied to the two electrodes are transferred to the individual light emitting layers of the combined light emitting units, And is recombined with another charge carrier. Optionally, the light emitting unit may comprise a so-called block layer for electrons or holes, by which movement of a particular charge carrier in the corresponding layer region is inhibited. The charge carrier transport layer may be electrically p- or n-doped. On the other hand, these devices are described in patent documents US 2009/0009072 A1 and US 2008/045728 A1.

An object of the present invention is to produce an organic light emitting device having a simple structure in which a stack of an organic layer having a light emitting unit and at least one connecting unit is disposed between an electrode and a counter electrode and whose efficiency is improved.

This object is achieved by the present invention through an organic light emitting device according to independent claim 1. Advantageous embodiments of the invention are subject of dependent claims.

1 shows a schematic view of an organic light emitting element in which an electrode 1, that is, an anode, and a counter electrode 2, that is, a stack 3 of organic layers are formed between cathodes.

The basic idea underlying the present invention is an electrode comprising: an electrode; An opposing electrode; And at least two light emitting units each having a light emitting layer disposed between the electrode and the counter electrode, and at least one connecting unit disposed between the adjacent light emitting units and formed according to one of the following embodiments An organic light emitting device having a stack:

A first connecting unit having an electrically p-doped hole transporting layer and an n-dopant layer made from an organic n-doping material, wherein the n-dopant layer is disposed adjacent to the light emitting layer, A first connecting unit having a HOMO level higher than 2.8 eV; And

A second connecting unit having a p-dopant layer made from an organic n-doped electron transporting layer and an organic p-doping material, wherein the p-dopant layer is disposed adjacent to the light emitting layer and the organic p- And a second connection unit having a LUMO level of less than 4.5 eV.

The organic light emitting element preferably emits white light. In this case, it may be provided to form a light emitting unit to emit different color light, wherein all of the colored light is combined together to form white light.

A preferred development of the present invention provides that at least one connection unit is formed with an organic interlayer made from an organic matrix material, wherein the interlayer is not electrically doped,

In the case of the first connecting unit, between the electrically p-doped hole transporting layer and the n-dopant layer, wherein the organic matrix material of the intermediate layer is electrically n-doped with the organic n-doping material of the n-dopant layer And / or electrically p-doped with p-doped material of the hole transport layer,

- in the case of the second connecting unit, between the electrically n-doped electron transporting layer and the p-dopant layer, wherein the organic matrix material of the intermediate layer is electrically p-doped with the organic p-doped material of the p- And / or electrically n-doped with an n-doped material of the electron transport layer.

In this embodiment, the electrically doped charge carrier transport layer and the dopant layer are spaced from each other in the individual connection units and are not in direct contact with the intermediate layer disposed between these layers. The intermediate layer is made from an electrically-dopable organic matrix material. However, the interlayer itself is not electrically doped. The intermediate layer preferably has a molecular weight of up to 400 g / mol, preferably up to 600 g / mol, of the organic doping material used in the adjacent charge carrier transporting layer, i. E. P-doped hole transporting layer or n-doped electron transporting layer . In this embodiment, the intermediate layer contains no metal and contains no pure organic compounds. The intermediate layer preferably comprises a single material (greater than 99% by volume).

The intermediate layer preferably exhibits a layer thickness of 0.5 nm to 5 nm, more preferably 1 nm to 3 nm.

The material in the intermediate layer preferably has a very high crystallization temperature. Also, a very high glass transition temperature (T _g ), preferably a glass transition temperature of more than 170 ° C, is preferred. An intermediate layer material preferably does not exhibit a T _g. Another desirable property of the interlayer material is a sublimation temperature of 250 DEG C or higher, preferably 300 DEG C or higher.

The material of the intermediate layer is preferably electrically dopeable by at least one of the dopants in the adjacent layer. This means that the matrix material has a property of being electrically doped by the dopant, which does not mean that this layer is doped with the matrix material.

In one embodiment, the material of the interlayer is simultaneously p- and n-doped electrically. The material of the intermediate layer preferably has a high charge carrier mobility, a charge carrier mobility (for holes or electrons) of at least 10 ^-5 cm ² V ^-1 s ^-1 . To be able to be p- and n-doped by an organic dopant, the LUMO of the interlayer is preferably less than -2.2 eV (less) and the HOMO of the interlayer is greater than -5.8 eV (higher).

Suitable materials for the intermediate layer include, for example, organometallic complexes, metal-phthalocyanine (M-Pc), metal naphthalocyanine, ZnPc, CuPc, MgPc, H2-phthalocyanine, H2- - phenyl isoquinoline), metal triquinoxaline complex, metal tetraquinoxaline complex, Zr-tetraquinoxaline complex, Zr-tetra (2,3-dimethyl-quinoxaline complex), and hexaazatriphenylene.

The development of the present invention can provide that at least one of the following features is generated:

The proximal light emitting unit with respect to the electrode contacts the electrode with an electrically p-doped hole transport layer, the electrode is designed as an anode,

- the proximal light emitting unit with respect to the counter electrode is in contact with the counter electrode with an electrically n-doped electron transport layer, and the counter electrode is designed as a cathode.

In this embodiment, in the case of two electrodes, it is understood that the electrically-charged charge carrier transporting layer in each of the light-emitting units adjacent to each of them is in contact with the electrode. In another embodiment, this electrically doped charge carrier injection layer, which in each case is in contact with the electrode, can be replaced by a combination of a charge carrier injection layer and a charge carrier transport layer, which is not electrically doped. A charge carrier injection layer is formed between the charge carrier transport layer and the allocated electrode. Typical charge carrier injection layers are described, for example, in patent application US 2009/009071 A1.

A preferred development example of the present invention is that an electron blocking layer is formed on the side away from the anode in the electron p-doped hole transporting layer and a hole blocking layer is provided on the side away from the cathode in the electron n-doped electron transporting layer . This embodiment contemplates disposing a charge carrier block layer that is assigned on the side of the respective individual electrically-doped charge carrier transport layer to the assigned electrode.

In a practical embodiment of the present invention,

In the first connecting unit, the light emitting layer in the proximal light emitting unit with respect to the n-dopant layer is ambipolar or is carried out as an electron transporting layer, wherein the charge carrier mobility for electrons is at least as large as the charge carrier mobility for holes (Approximately 1000 cd / m < ² > for typical operating conditions), and

In the case of the second connecting unit, the emitting layer in the proximal light emitting unit with respect to the p-dopant layer is either polar or is implemented as a hole transporting layer, wherein the charge carrier mobility for holes is at least approximately (Approximately 1000 cd / m < ² > in the case of normal operating conditions) can be provided.

The bipolar embodiment of the charge-carrier transport layer means that both the holes and the electrons can be moved by this layer, wherein the charge carrier mobility for electrons in the case of the electron transport layer is dependent on the charge carrier mobility The same or larger. In the case of the second connecting unit, this means that for the hole transporting layer, the charge carrier mobility for the holes in the bipolar embodiment is roughly equal to or greater than the charge carrier mobility for electrons in this layer.

An advantageous embodiment of the invention is that the organic n-doping material has a molecular weight greater than 350 g / mol, a molecular weight greater than 550 g / mol in the case of the first connecting unit and an organic p- The material is a metal-free material and has a molecular weight greater than 350 g / mol, preferably greater than 550 g / mol.

Electrical p- or n-doping within the meaning of the present application exists when the organic doping material deposited in the individual matrix material increases the electrical conductivity of the matrix by at least 10 times. Alternatively, the electrical doping of organic matrix material features may be specified by an organic doping material as follows. The following is for an n-doped material: HOMO_n-doped material <LUMO_matrix material + 0.5 eV. The following are for organic p-doped materials: LUMO_p-doped material> HOMO_matrix material - 0.5 eV. In this case, the energy numbers for HOMO (highest occupied molecular orbital) and LUMO (lowest unoccupied molecular orbital) are negative.

It is further advantageous that the n-dopant of the connecting unit is a metal-free member.

In another embodiment, the light emitting device can be made in the following layer order:

EML / n-dopant / p: HTL / EML

EML / p-dopant / n: ETL / EML

When the organic intermediate layer (OIL) is considered:

EML / n-dopant / OIL / p: HTL / EML

EML / p-dopant / OIL / n: ETL / EML

When the blocking layer is considered (EBL, HBL):

EML / n-dopant / p: HTL / EBL / EML

EML / p-dopant / n: ETL / HBL / EML

Providing intermediate and blocking layers:

EML / n-dopant / OIL / p: HTL / EBL / EML

EML / p-dopant / OIL / n: ETL / HBL / EML

In the exemplary embodiment described above, the list of layers for the individual layer structure between the electrode and the counter electrode is all listed. The individual layer structure is limited to the identified layers.

Other exemplary embodiments of the present invention are described in further detail below.

The individual light emitting layers in the light emitting unit are preferably formed by introducing one or more light emitting materials into the organic matrix material. The following materials can be used as matrix materials primarily to transfer charge carriers in the form of holes: a-NDP, TCTA, CBP (4,4'-N, N'-dicarbazole- Bis [carbazolyl] benzene), TCPB (1,3,5-tris [4- (N-carbazolyl) phenyl] benzene), mCP (N, N'-dicarbazolyl- , TCB (1,3,5-tris [carbazolyl] benzene) and CDBP (4,4'-bis [9-carbazolyl] 2,2'-dimethyl-biphenyl).

The following materials can be used primarily as matrix materials to transfer charge carriers in electronic form: SEB084 (commercially available from the manufacturer Merck), TPBI (1,3,5-tris [N-phenylbenzimidazol- Benzene, TAZ-1 (3-phenyl-4- [1'-naphthyl] -5-phenyl-1,2,4-triazole), TAZ- Phenyl-5-tert-butylphenyl-1,2,4-triazole), TAZ-3 ), PBD (2- [4-biphenyl] -5- [4- tert -butylphenyl] -1,3,4-oxadiazole) and TMM004 (commercially available from manufacturer Merck).

The properties of the various materials involved can be described by the energy layers of the lowest unoccupied molecular orbital (LUMO, synonym: ionization potential) and highest occupied molecular orbital (HOMO, synonym: electron affinity).

One way to determine the ionization potential (IP) is by ultraviolet photoelectron spectroscopy (UPS). Although the ionization potential is usually determined for a solid body, it is also possible to measure the ionization potential in the gas phase. The two variables are distinguished by a solid body effect, such as the polarization energy of a hole formed in a photoionization process, for example. Typical values for the polarization energy are approximately 1 eV, but larger deviations therefrom can also occur [Sato et al., J. Chem. Soc. Faraday Trans 2, 77, 1621 (1981)].

The ionization potential is in this case the initiation of the ionization spectrum in the region of the high kinetic energy of the photoelectron, in other words, the energy of the weakest coupled photoelectron.

An associated method, inverted photoelectron spectroscopy (IPES), can be used to determine the electron affinity (EA) (see, for example, Gao et. al., Appl. Phys. Lett. 82, 4815 (2003)). However, this method is a very uncommon method. Alternatively, the solid body energy level can be determined by an electrochemical oxidation measurement (Eox) or a reduction potential (Ered) in solution. Suitable methods include, for example, cyclic voltammetry (see, for example, Ander-son, J. Amer. Chem. Soc. 120, 9646 (1998)).

No empirical formula for converting the reduction potential to an electron affinity is known. This is because it is difficult to determine the electron affinity. Thus, a simple rule is often applied: IP = 4.8 eV + e ^* Eox (large ferrocene / ferrocenium) or EA = 4.8 eV + e ^* Ered (great ferrocene / ferrocenium). When other reference electrodes or reduction pairs are used to refer to electrochemical potentials, conversion methods are known.

Although not precisely calibrated, it is common that the term "HOMO energy" E (HOMO) or "LUMO energy" E (LUMO) is used synonymously with the term ionization energy or electron affinity [Koopmans theorem]. In this respect, it is important to ensure that the higher the ionization potential and the electron affinity, the higher the value, the more dissolved or the binding of the attached electrons becomes stronger. The energy magnitude of the molecular orbital function (HOMO, LUMO) is the opposite. Thus, based on a rough approximation, the following equations apply: IP = -E (HOMO) and EA = E (LUMO).

The specified potential corresponds to the solid body potential.

The dopant within the meaning of the present invention is an electrical dopant, which increases the density of charge carriers on the matrix (transport material) through charge transport and thereby changes the position of the Fermi level. Such dopants and doping should be distinguished from chemical reactions that alter the transport material; These will also be distinguished from mixtures of two different transport materials. Electrodoping and emitter doping to the dye should also be distinguished.

Exemplary embodiments relating to organic n-doped materials are described in more detail below.

The n-dopant is a molecule and / or a neutral radical with a HOMO level (solid body ionization potential) greater than -3.3 eV, preferably greater than -2.8 eV (more positive). The HOMO of the dopant can be determined from the cyclic voltammetry measurement of the oxidation potential. Alternatively, the reduction potential of the dopant cation can be determined in the salt of the dopant. The dopant will exhibit an oxidation potential, which is less than or equal to about -1.5 V, preferably less than or equal to about -2.0 V, and more preferably less than about -2.0 V, as compared to Fc / Fc + (ferrocene / ferrocenium redox pair) -2.2 V or less. The molecular weight of the dopant is preferably 200 to 2000 g / mol, preferably 500 to 2000 g / mol.

The molar doping concentration is preferably 1: 1000 (dopant molecule: matrix molecule) to 1: 5, preferably 1: 100 to 1: 5, more preferably 1: 100 to 1:10. In each case, it is also possible that the doping ratio is also used at a concentration greater than 1: 5.

The dopant may be formed from precursors only during the layer production process or subsequent layer production process (cf. DE 103 07 125). The HOMO level of the stated dopant refers to the species obtained.

Patent document DE 10 2004 010 954 describes the use of electron-rich metal complexes as donors in organic semiconductor materials. Examples of electron-rich metal complexes include tetrakis (1,3,4,6,7,8-hexahydro-2H-pyrimido [1,2-a] pyrimidinate) dichromium (II) Or tetrakis (1,2,3,3a, 4,5,6,6a, 7,8-decahydro-1,9,9b-triazapanalenyl) di-bromram (II).

In many cases, the LUMO of the p-dopant (the HOMO of the n-dopant) is at most 0.5 eV larger (up to 0.5 eV small) than the p-type (n-type) HOMO (LUMO) for p- ) Is advantageous. In this case, according to the regulations, the HOMO and LUMO variables are considered to be the same in terms of the amount of ionization potential or electron affinity, but have opposite signs.

A dopant from the patent document EP 2 002 492 is also preferred.

Preferred n-dopants include Cr ₂ hpp ₄ (an anion of hpp: 1,3,4,6,7,8-hexahydro-2H-pyrimido [1,2-a] pyrimidine); Fe ₂ hpp ₄ ; Mn ₂ hpp ₄ ; Co ₂ hpp ₄ ; Mo ₂ hpp ₄ ; W ₂ hpp ₄ ; Ni ₂ hpp ₄ ; Cu ₂ hpp ₄ ; Zn ₂ hpp ₄ ; W (hpp) ₄ ; 4,4 ', 5,5'-tetracyclohexyl-1,1', 2,2 ', 3,3'-hexamethyl-2,2', 3,3-tetrahydro-1H, 2,2'-biimidazole;2,2'-diisopropyl-1,1',3,3'-tetramethyl-2,2', 3,3 ', 4,4', 5,5 ', 6,6', 7,7 '-Dodecahydro-1H, 1'H-2,2'-bibenzo [d] imidazole; 2,2'-diisopropyl-4,4 ', 5,5'-tetrakis (4-methoxyphenyl) -1,1', 3,3'-tetramethyl-2,2 ', 3,3 '-Tetrahydro-1H, 1'H-2,2'-biimidazole; Bis (2-methoxyphenyl) -4 ', 5'-bis (4-methoxyphenyl) -1,1', 3,3'-tetramethyl- 2,2 ', 3,3'-tetrahydro-1H, 1'H-2,2'-biimidazole; Bis (2-methoxyphenyl) -4 ', 5'-bis (3-methoxyphenyl) -1,1', 3,3'-tetramethyl- 2,2 ', 3,3'-tetrahydro-1H, 1'H-2,2'-biimidazole.

Particularly preferred are dopants which do not represent any metal.

Other exemplary embodiments of the organic p-doped material are described below.

The p-dopant is a molecule and / or a neutral radical having a LUMO level of less than -4.5 eV (preferably less than -5.1 eV, more preferably less than -5.3 eV) (even more negative). The LUMO of the receptor can be determined from cyclic voltammetry measurements of the reduction potential, which is greater than or equal to about -0.3 V, preferably greater than or equal to about 0.0 V, and more preferably greater than or equal to about 0.24 V Is greater than or equal to.

The molecular weight of the receptor is preferably 200 to 2000 g / mol, preferably 300 to 2000 g / mol, more preferably 400 g / mol to 2000 g / mol.

The molar doping concentration is preferably 1: 1000 (receptor molecule: matrix molecule) to 1: 5, preferably 1: 100 to 1: 5, more preferably 1: 100 to 1:10. In each case, it is also possible that the doping ratio is also used at a concentration higher than 1: 5.

The acceptor may only form from the precursor during the layer production process or subsequent layer production process. The LUMO level of the indicated receptor refers to the species obtained.

Patent document DE 103 57 044 describes the use of quinones and their derivatives as acceptors in organic semiconductor materials. Receptors include, for example, 2,2,7,7-tetrafluoro-2,7-dihydro-1,3,6,8-dioxa-2,7-diborane-pentachloro-benzo [e] Pyrene or 1,4,5,8-tetrahydro-1,4,5,8-tetrathia-2,3,6,7-tetracyanoanthraquinone or 1,3,4,5,7,8- Hexafluoronaphtho-2,6-quinonetetracano-methane.

Other preferred p-dopants are known from patent document US 2008/265216 A1.

Preferred p-dopants include 2,2 '- (perfluoronaphthalene-2,6-diylidene) dimalononitrile; 2,2 '- (2,5-dibromo-3,6-difluorocyclohexa-2,5-diene-1,4-diylidene) dimalononitrile; (2E, 2'E, 2 "E) -2,2 ', 2" - (cyclopropane-1,2,3-triylidene) tris (2- (2,6- Difluoro-4- (trifluoromethyl) phenyl) acetonitrile); 4,4 ', 4 "-cyclopropane-1,2,3-triylidene tris (cyanomethan-1-yl-1-ylidene) tris (2,3,5,6-tetrafluorobenzonitrile) .

Exemplary embodiments of materials in the charge-carrier transport layer and the charge carrier transport layer are described in more detail below.

The matrix material for the hole transport layer is usually a neutral, non-radically conjugated molecule. By doping with a receptor compound, similarly one transversely (negatively charged) charged cation of the matrix material is formed. When a transversely charged cation is formed, it is a radical cation. Accordingly, the layer formed from the matrix material and the dopant contains the neutral molecules of the matrix material and the cations of the matrix material formed by doping.

As a general rule, the charge state of a matrix molecule is altered by doping through one or several positive charges. For example, when the matrix material itself is an anion, the anion is converted to a neutral molecule or cation by doping.

The hole transport layer (including the corresponding blocker) typically has a HOMO in the range of -4.5 to -5.5 eV (sub-vacuum level), a LUMO in the range of -1.5 eV to -3 eV, an emission layer material , The HOMO is in the range of -5 eV to -6.5 eV, the LUMO is in the range of -2 to -3 eV, in the case of the electron transport material (including the corresponding blocker), the HOMO is in the range of -5.5 eV to -6.8 eV And the LUMO is -2.3 to -3.3 eV. The work function of the contact material is typically about -4 to -5.3 eV for the anode and -2.7 to -4.5 eV for the cathode.

In addition, the requirement for a matrix material for a hole transport layer is that such a matrix material has a relatively high mobility for holes. In this case, a hole mobility of > ¹ x 10 ^-8 cm ² V ^-1 s ^-1 , preferably> 1 x 10 ^-6 cm ² V ^-1 s ^-1 , is advantageous. The matrix material for the hole transport layer exhibits a hole mobility higher than the electron mobility under the operating conditions (typically 10 mA / cm ² ).

In particular, when the device is produced using a solvent process, a polymer matrix material can also be considered. Similar requirements relate to this material in relation to mobility and oxidation potential. Suitable matrix materials may be, for example, polythiophene or derivatives thereof.

Examples of possible matrix materials for the electron transporting layer are fullerenes such as C60, oxadiazole derivatives such as 2- (4-biphenyl) -5- (4- tert -butylphenyl) -1,3 , 4-oxadiazole, quinoxaline-based compounds such as bis (phenylquinoxaline), or oligothiophene, perylene derivatives such as perylene tetracarboxylic di-anhydride, naphthalene derivatives, Naphthalene tetracarboxylic acid di-anhydride or other electron transport materials such as, for example, AP Kulkarni et al., Chem. Mater. 2004, 16, 4556).

Materials such as C60 and NTCDA are not used in certain applications and for example C60 is not used in OLEDs with blue emission (e.g., white or cyan) as the transport layer because C60 is highly absorbing and at the same time C60 LUMO is too low. NTCDA is transparent but crystallizes at 85 캜.

Other possible matrices for the electron transporting layer include, for example, quinolinato complexes of aluminum or other rare earth metals, in which case quinolinato ligands are also substituted. In particular, the matrix metal may be tris (8-hydroxy-quinolinato) -aluminum. Other aluminum complexes with O- and / or N-donor atoms can be used if desired. The quinolinato complexes may contain, for example, one, two or three quinolinato ligands, in which case the other ligands may contain a central atom, preferably an O- and / or N- To form a complex.

The matrix material for the electron transport layer is usually a neutral, non-radically conjugated molecule. By doping with the donor compound, a corresponding monovalent (more rarely charged) charged anion of the matrix material is produced. When a uncharged anion is formed, it is a radical anion. Accordingly, the layer formed from the matrix material and the dopant contains the neutral molecules of the matrix material and the anions of the matrix material formed by doping.

As a general rule, the charge state of a matrix molecule is altered by doping through one or more negative charges. For example, when the matrix material itself is a cation, doping converts the cation to a neutral molecule or anion.

The matrix material for the electron transport layer in organic light emitting diodes often exhibits a reduction potential of -2.4 V compared to -1.9 V to Fc / Fc + compared to Fc / Fc +.

In addition, the requirement of a matrix material for an electron transport layer is that the matrix material has a relative mobility to electrons. In this case, electron mobility of > ¹ x ^10-8 cm ² V ^-1 s ^-1 , preferably> 1 x 10 ^-6 cm ² V ^-1 s ^-1 , is advantageous. The matrix material for the electron transport layer exhibits electron mobility higher than the hole mobility under the operating conditions (typically 10 mA / cm &lt; ² &gt;).

In particular, where the device is produced using a solvent process, a polymer matrix material can also be considered. Similar requirements apply to this material for mobility and reduction potential. Suitable matrix materials may be, for example, polyfluorenes or derivatives thereof.

Also heteroaromatics, such as in particular, triazole derivatives, possibly pyrrole, imidazole, triazole, pyridine, pyrimidine, pyridazine quinoxaline, pyrazino-quinoxaline, etc., can be used as the matrix material. The heteroaromatic is preferably substituted, especially aryl-substituted and, for example, phenyl- or naphthyl-substituted.

Preferred exemplary embodiments of the present invention Concrete example

Preferred exemplary embodiments of the present invention are described in more detail below with reference to the drawings.

1 shows a schematic view of an organic light emitting element in which a stack 3 of organic layers is formed between an electrode 1, i.e., an anode, and an opposite electrode 2, that is, a cathode. The stack 3 of organic layers consists of a light emitting unit 4 and a further light emitting unit 5 and a connecting unit 6 arranged between the two light emitting units 4 and 5. [ The light emitting unit 4 is formed of the light emitting layer 8 in contact with the hole transporting layer 7 and the connecting unit 6. [ The other light emitting unit 5 is adjacent to the counter electrode 2 with an electron transport layer 9 and an assigned light emitting layer 10 disposed adjacent to the connection unit 6. [ The hole transport layer 7 may be electrically p-doped. Alternatively or additionally, the electron transport layer 9 may be electrically n-doped.

In a different embodiment from the schematic drawing, a hole blocking layer may be formed between the electron transport layer 9 and the light emitting layer 10 in another light emitting unit 5. Alternatively or additionally, the electronic block layer can be formed on the side remote from the counter electrode 2 in the light emitting layer 10 of the other light emitting unit 5.

The connecting unit 6 is composed of three organic layers in the embodiment shown in the figure. In a first embodiment of the connecting unit 6, the first layer 20 is formed as an n-dopant layer made of an organic n-doping material, and the matrix n-doping material of the electron- Is electrically n-doped in the other light-emitting unit 5. In this variant, the second layer of connecting unit 6 is an electrically p-doped hole transporting layer. The third layer 22 of the connecting unit 6 is designed as an intermediate layer. The intermediate layer can be electrically n-doped with the organic n-doping material of the n-dopant layer in this embodiment and / or electrically p-doped with the p-doping material of the hole transporting layer 7 in the light emitting unit 4 .

In another embodiment, the second layer 21 in the connection unit 6 is a p-dopant layer made from an organic p-doped material and the hole transport layer The matrix material of 7) is electrically p-dopable. In this embodiment, the first layer 20 of the connecting unit 6 is formed as an electrically n-doped electron transporting layer. The third layer 22 forming the interlayer is designed with the matrix material in this embodiment, which can be electrically p-doped with the organic p-doped material of the p-dopant layer and / And is electrically n-doped with an n-doped material of the electron transport layer 9. [

Exemplary embodiments of the organic light emitting device of the drawings are described below.

Example  1 (White light emission)

A base electrode of ITO was formed on the glass substrate. This was followed by a subsequent stack of organic layer and top electrode:

(3 mol%) of 2,2 ', 2 "- (cyclopropane-1,2,3-triylidene) tris (2- (p-cyanotetrafluorophenyl) acetonitrile) (N, N'-bis (naphthalen-1-yl) -N, N'-bis (phenyl) -benzidine doped with a)

10 nm a-NPD;

A 10 nm blue emissive layer doped with an emitter dopant (commercial material), this emissive layer comprising a blue emissive layer doped with 5 mol% EK9, for example 10 nm blue Can be replaced by an emissive layer (both sources: Eastman Kodak);

10 nm 4- (naphthalen-1-yl) -2,7,9-triphenylpyrido [3,2-h] quinazoline;

As the n: ETL of the connecting unit, 1,1 ', 2,2', 3,3'-hexamethyl-4,4 ', 5,5'-tetrakis (4-methylcyclohexyl) (Naphthalene-1-yl) -2,7,9-triphenylpyrido [3, 3'-tetrahydro-1H, 1'H-2,2'-biimidazole (10 mol% 3,2-h] quinazoline;

5 nm CuPc as an interlayer of the connecting unit;

HTL2 or 3 mol% 2,2 ', 2 "- (cyclopropane-1,2,3-triylidene) tris (2- (p-cyanotetrafluorophenyl) acetonitrile) as 3 nm (ODS) &Lt; / RTI &gt; doped a-NPD;

10 or 0 nm a-NPD as EBL2;

A-NPD doped with 10 mol% RE-076 (ADS) as EML2;

10 nm 2,4,7,9-tetraphenyl-1,10-phenanthroline as HBL 2;

1,1 ', 2,2', 3,3'-hexamethyl-4,4 ', 5,5'-tetrakis (4-methylcyclohexyl) -2,2', 3,3'-tetrahydro (Naphthalen-1-yl) -2,7,9-triphenylpyrido [3, 2-h ] Quinazoline;

100 nM Al.

The following abbreviations were used: HTL - hole transport layer, ETL - electron transport layer, EML - light emitting layer, EBL - electron blocking layer, and HBL - hole blocking layer. n: ETL means that the electron transport layer is electrically n-doped.

The layer thickness of the ETL is dependent on the layer thickness variation of the HTL, so that the optical cavity and result remain similar. The following table shows the layer thicknesses for four different devices.

ODS - Organic doping material layer

Although device A and device C are simplified, they exhibit the same or even better features than comparative examples B and D. The 5 nm CuPc interlayer may also be omitted.

Example  2

Again, a base electrode of ITO was formed on the glass substrate and a subsequent layer structure was formed thereon as follows:

Doped with 2,2 ', 2 "- (cyclopropane-1,2,3-triylidene) tris (2- (p-cyanotetrafluorophenyl) acetonitrile) (3 mol%) as HTL1, a-NPD;

10 nm a-NPD;

40 nm blue emissive layer of BH121 doped with 5 mol% EK9 (both sources: Eastman Kodak);

(1, 2,3,4,6,7,8-hexahydro-2H-pyrimido [1,2-a] pyrimidinate) ditungsten (II) as the n-dopant layer of the connecting unit or 15 nm n: ETL as a comparative example;

5 nm CuPc as an interlayer of the connecting unit;

15 nm doped with 2,2 ', 2 "- (cyclopropane-1,2,3-triylidene) tris (2- (p-cyanotetrafluorophenyl) acetonitrile) (3 mol% a-NPD;

20 nm a-NPD doped with 10 mol% RE-076 (ADS) as EML2;

10 nm 2,4,7,9-tetraphenyl-1,10-phenanthroline as HBL 2;

4,4 ', 5,5'-tetracyclohexyl-1,1', 2,2 ', 3,3'-hexamethyl-2,2', 3,3'-tetrahydro-1H, 1'H 60 nm 4- (naphthalen-1-yl) -2,7,9-triphenylpyrido [3,2-h] quinazoline doped with 2,2'-biimidazole (10 mol%);

100 nM Al.

It has also been shown here that at least the simplified embodiments as well as the comparative examples work.

It is important that the features of the invention described in the foregoing description, the claims, and the drawings, individually and in any combination, be combined for realization of the invention in different embodiments thereof.

Claims (6)

The electrodes (1),
The counter electrode (2) and
An electrode 1 and an opposing electrode 2 having two or more light emitting units 4 and 5 each having a light emitting layer 8 and at least one connecting unit 6 arranged between adjacent light emitting units 4 and 5, (3) arranged between a pair of substrates (2), wherein at least one connecting unit (6)
- a first connecting unit having an electrically p-doped hole transport layer comprising a first matrix material and a p-dopant, and an n-dopant layer (20) made from an organic n-doped material, 20) is disposed adjacent to the light-emitting layer (8) and the organic n-doping material has a HOMO level greater than -3.3 eV, and
- a second connecting unit having an electrically n-doped electron transporting layer comprising a second matrix material and an n-dopant, and a p-dopant layer (21) made from an organic p-doping material, the p-doping layer 21) is disposed adjacent to the light emitting layer (10) and the organic p-doped material is formed according to one of the second connection units having a LUMO level lower than -4.5 eV. 2. A method according to claim 1, wherein in the at least one connecting unit (6) the organic interlayer (22) is made from an organic material, which is not electrically doped,
In the case of the first connecting unit, between the electrically p-doped hole transporting layer and the n-dopant layer 20, the organic matrix material of the intermediate layer is disposed between the organic n-doping material 20 of the n-dopant layer 20 And / or electrically p-doped with the p-doped material of the hole transport layer,
- in the case of the second connecting unit, between the electrically n-doped electron transporting layer and the p-dopant layer 21, and the organic matrix material of the intermediate layer is deposited on the organic p-doped material 21 of the p- , And / or electrically n-doped with an n-doped material of the electron transport layer. 3. The method according to claim 1 or 2,
A light emitting unit adjacent to the electrode 1 is in contact with the electrode 1 with an electrically p-doped hole transport layer, the electrode 1 is run as an anode,
In which the light emitting unit adjacent to the counter electrode 2 is in contact with the counter electrode 2 as an electronically transported layer which is electrically n-doped and in which the counter electrode 2 is implemented as a cathode, . The method of claim 3,
- an electron blocking layer is provided on the side remote from the anode in the electron p-doped hole transport layer,
- the hole blocking layer is provided on the side remote from the cathode in the electron n-doped electron transport layer. 3. The method according to claim 1 or 2,
In the case of the first connecting unit, the electron transporting layer in the light emitting unit 4 adjacent to the n-dopant layer 20 is either polar or is carried out as an electron transporting layer, where the charge carrier mobility for electrons is proportional to the charge carrier At least equal to the mobility,
In the case of the second connecting unit, the hole transporting layer in the light emitting unit 5 adjacent to the p-dopant layer 21 is either polar or is carried out as a hole transporting layer, where the charge carrier mobility for the holes is proportional to the charge carrier At least equal to the mobility. 3. The method according to claim 1 or 2,
In the case of the first connecting unit, the organic n-doping material has a molecular weight greater than 350 g / mol,
In the case of the second connecting unit, the organic p-doping material is metal-free and has a molecular weight greater than 350 g / mol.

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