WO2011131185A1

WO2011131185A1 - Mixture for producing a doped semiconductor layer

Info

Publication number: WO2011131185A1
Application number: PCT/DE2011/075083
Authority: WO
Inventors: Michael Felicetti; Volker Lischewski; Mirko Tschunarjew; Carsten Rothe; Sascha Dorok; Ansgar Werner
Original assignee: Novaled Ag
Priority date: 2010-04-21
Filing date: 2011-04-20
Publication date: 2011-10-27

Abstract

The invention relates to an organic semiconductor layer, comprising at least one matrix material and at least one doping material, characterized in that the doping material is selected from compounds of formula (I), where R1 is independently selected from aryl and heteroaryl, aryl and heteroaryl being substituted, preferably completely substituted, by at least one electron-deficient substituent, and further characterized in that the matrix material is selected from compounds of formula (2) or compounds of formula (2), at least one H of formula (2) being substituted by aromatics and/or heteroaromatics and/or C1-C20 alkyl. The invention further relates to a mixture comprising at least one matrix material and at least one doping material for producing a doped semiconductor layer.

Description

Mixture for producing a doped semiconductor layer

The present invention relates to the use of 3-radial compounds as an organic dopant for doping an organic semiconducting matrix material for changing the electrical properties thereof. Also, the invention relates to organic semiconducting materials and electronic components in which the 3-radial compounds are used.

For some years it has been known that it is possible to strongly influence organic semiconductors by doping (electrical doping) with regard to their electrical conductivity. Such organic semiconductive matrix materials can be constructed from either compounds with good electron donating properties or from compounds having good electron acceptor properties. For doping electron donating materials (HT), strong electron acceptors such as tetracyanoquinone dimethane (TCNQ) or 2,3,5,6-tetrafluoro-tetracyano-1,4-benzoquinone dimethyne (F4TCNQ) have become known (US7074500). These generate by electron transfer processes in electron donor-like base materials (hole transport materials) so-called. Holes, the number and mobility of which changes the conductivity of the base material more or less significantly. Examples of suitable matrix materials with hole transport properties are Ν, Ν'-perarylated benzidines TPD or Ν, Ν ', Ν'-perarylated starburst compounds, such as the substance TDATA, or else certain metal phthalocyanines, in particular zinc phthalocyanine ZnPc.

However, the compounds described so far have disadvantages in the production of doped semiconductive organic layers or of corresponding electronic components with such doped layers for a technical application, since the manufacturing processes in large-scale production plants or those on a pilot plant scale can not always be controlled with sufficient precision, resulting in high control and control effort within the processes leads to a desired Product quality or unwanted tolerances of the products. Furthermore, there are disadvantages in the use of previously known organic dopant end with respect to the electronic component structures, such as light-emitting diodes (OLEDs), field effect transistor (FET) or solar cells themselves, since the mentioned production difficulties in handling the dopants to unwanted irregularities in the electronic components or unwanted aging effects of the electronic Can lead components. At the same time, however, it should be noted that the dopants to be used have extremely high electron affinities (reduction potentials) and other properties suitable for the application, since, for example, the dopants also determine the conductivity or other electrical properties of the organic semiconductive layer under given conditions. Decisive for the doping effect are the energetic layers of the HOMO of the matrix material and the LUMO of the dopant.

Electronic devices with doped layers are i.a. OLEDs and solar cells. OLEDs are known, for example, from US Pat. No. 7,355,197 or US 2009/051271. Solar cells are known, for example, from US 2007/090371 and US 2009/235971.

It is an object of the present invention to overcome the disadvantages of the prior art, in particular to provide doped organic semiconductors doped with 3 -radial compounds.

This object is solved by the independent claims 1 and / or 10 of the present application. Preferred embodiments will be apparent from the dependent claims.

A preferred alternative of the invention provides that the following layer sequences are present in the component: (i) anode / dopant / HTM; (ii) anode / dopant: HTM. Also preferred is: (iii) dopant / HTM / EML or dopant / HTM / OAS; (iv) p-doped HTM / EML or dopant: HTM / OAS. The p-doped HTM is mixed with the invention Dot doped. EML is the "emission layer" of an OLED, OAS stands for "optical absorption layer of a solar cell" (typically a DA hetero-junction).

It is further preferred that the layer sequences (i) - (iv) are final layer sequences. In the literature, doped hole transport layers or materials for forming these transport layers are based either on the properties of the dopant or on the properties of the hole transport material. The other component is described in general reference to the prior art. In fact, for devices with a doped hole transport layer, generally better results are achieved than for a device having the same structure but without the dopant in the hole transport layer. Due to this limited approach, however, it is overlooked that in order to fully optimize the overall properties of the component, the targeted adaptation of hole transport material and dopant to one another must take place as the next step. In particular, it should be noted that the most suitable hole transport material for a doped layer is not necessarily the one that functions best as undoped hole transport material. Rather, Dotand and Matrix form a system that must be considered in its entirety.

A central parameter for a hole transport material in an undoped layer is the so-called charge carrier mobility for holes. This determines how much voltage drops across this layer when a certain current density flows through this layer. Ideally, the charge carrier mobility is so high that the voltage drop across the single layer is negligible compared to the voltage drop across the entire device. In this case, this layer is no longer limiting the current flow, and the charge carrier mobility can be considered to be sufficiently optimized. In practice, this level has not yet been reached. Especially for colorless (in the visible non-absorbing) hole transport materials a significant voltage for driving the current flow through hole transport layers is needed. This is all the more true if the thickness of this layer should not only be chosen to be minimal, but must have a certain minimum layer thickness (> 50 nm), for example for process-technical reasons or for reasons of component stability. In this situation, the selection of a good hole transport material for this layer must first orients itself to a maximum charge carrier mobility in order to limit the negative consequences on the performance parameters of the device. Other parameters that describe the material, such as glass transition temperature (Tg), processing properties, cost of producing the material, take a back seat. For this reason, a-NPD with its very high charge carrier mobility is considered to be one of the best hole transport materials, despite its comparatively low glass transition temperature of only 96 ° C. As a result, a-NPD is also used commercially for the production of OLED products, although the low glass transition temperature was recognized as a disadvantage of this solution, but must be accepted.

The situation is different for a 3 -radio-doped hole transport layer. The inventors have found that a minimal voltage drop across the doped hole transport layer can be achieved for a larger number of hole transport materials. The doping effect of the 3 -radial compounds makes the layer conductive. The conductivities are for a large number of hole transporting materials above the threshold value of 10 ^"5 S / cm. Fall For this conductivity at a comparatively high current density of 100 mA / cm ² over a comparatively large layer thickness of 100 nm only 0.1 V ab. In particular, for This value is not very significant for OLED devices with a typical operating voltage of at least 3 V. In this context, it is important to recognize that among the hole transport materials functioning in doped hole transport layers, there are some such materials that can be used in one undoped hole transport layer showed insufficient suitability and therefore were not previously used for the production of components. Furthermore, it is important to realize that this fact opens up new degrees of freedom for the selection of hole transport materials for doped hole transport layers. The inventors have therefore set themselves the task of finding those hole transport materials that have the best possible performance in a doped hole transport layer, taking into account those materials that were not considered in conventional view. In fact, as a result of this study, it has been found that the best combination of 3-radial compounds and hole transport materials is not that which combines the 3-radial compounds with the conventional best hole transport materials (those with high charge carrier mobility). This will be demonstrated on the basis of the exemplary embodiments.

3-radial connections

In the following, some preferred 3-radialenes are shown, which can be advantageously used for the purposes according to the invention:

Wherein each Rl is independently selected from aryl and heteroaryl, wherein aryl and heteroaryl are at least partially, preferably fully substituted with electron-deficient compound (acceptor groups).

Aryl is preferably phenyl, biphenyl, a-naphthyl, b-naphthyl, phenanthryl, anthracyl, heteroaryl is preferably pyridyl, pyrimidyl, triazyl, quinoxalinyl

Acceptor groups are Electron-withdrawing groups preferably selected from are fluorine, chlorine, bromine, CN, trifluoromethyl, nitro.

General synthesis is described in the patent application EP1988587 under "Preparation of the Oxocarbon, Pseudooxocarbon or Radial Structures" Selection of the Matrix Material

In the present invention, suitable dopants are described for organic semiconductive materials, such as hole transport materials HT, which are commonly used in OLEDs or organic solar cells. The semiconductive materials are preferably intrinsically hole-conducting. It has been found that the following materials are suitable matrix materials and can be doped with the 3 -radial compounds.

Preferred are matrix materials selected from the following formula

where A =

wherein X = methyl or tert-butyl, and Y is selected from: substituted or unsubstituted tetraphenylmethane, or substituted or unsubstituted phenantherene. Preferably, Y is selected from:

The broken bond indicates the binding site of the substituents.

Also preferred are the materials of formulas (2), (3), (4), and (5). Particularly preferred is the matrix material of the formula (2). Formula (2)

Formula (3)

Formula (4)

Formula (5)

The following compounds are preferred: HTM of Formula 2, HTM of Formula 3, HTM of Formula 4, HTM of Formula 5, where HTM of Formula 2 is the best material.

Furthermore Favor matrix materials are selected from the following formula (2) wherein at least one H of formula (2) is substituted by aromatics and / or heteroaromatic and / or C1-C20 alkyl. Further preferred are doped HTL (hole transport layer) wherein the matrix material is a material of the HTM of formula 3, HTM of formula 4, HTM of formula 5 and the dopant 2,2 ', 2 "- (cyclopropane-1, 2,3-triylidene ) tris (2- (p-cyanotetrafluorophenyl) acetonitrile).

Also preferred is a doped HTL wherein the matrix material is HTM of formula 2 and the dopant is 2,2 ', 2 "- (cyclopropane-l, 2,3-triylidene) tris (2- (p-cyanotetrafluorophenyl) acetonitrile).

Advantages of the doped HTL according to the invention: lower absorption, better conductivity, better temperature stability. Better overall performance compared to a-NPD.

Description of the figures

FIG. 1a Schematic representation of a doped hole transport layer (12) on a substrate (11), wherein the hole transport layer (12) is electrically contacted between two electrodes (13) and (14). Such a planar structure is e.g. used as resistor, routing path, etc.

Fig. Lb Schematic representation of a doped hole transport layer (17) between two electrodes (16) and (17) on a substrate (15). Additional layers may be present. Such a stacked layer construction is e.g. used in OLEDs, organic solar cells, etc.

, 2 Representation of the diode characteristics.

Electronic component Using the organic compounds according to the invention for producing doped organic semiconducting materials, which may be arranged in particular in the form of layers or electrical conduction paths, a multiplicity of electronic components or devices containing them can be produced. In particular, the dopants according to the invention for the production of organic light-emitting diodes (OLED), organic solar cells, organic diodes, especially those with high

3 7 4 7 5 7

Rectification ratio as 10 -10 'preferably 10 -10 or 10 -10 or organic field effect transistors are used. The dopants according to the invention can be used to improve the conductivity of the doped layers and / or to improve the charge carrier injection of contacts into the doped layer. Particularly in the case of OLEDs, the component may have a pin structure or an inverted structure, without being limited thereto. However, the use of the dopants according to the invention is not limited to the above-mentioned advantageous embodiments. Preference is given to OLEDs that are ITO free. Also preferred are OLEDs with at least one organic electrode. Preferred organic electrode (s) are conductive layers containing as main components the following materials: PEDOT-PSS, polyaniline, carbon nanotubes, graphite.

The typical structure of a standard OLED may be as follows: 1. Support, substrate, e.g. Glass

Electrode, hole injecting (anode = positive pole), preferably transparent, e.g. Indium tin oxide (ITO) or FTO (Braz J. Phys., V. 35 no.4 pp.1016-1019 (2005))

Third hole layer, 5. Holeside block layer to prevent exciton diffusion from the emission layer and prevent carrier leakage from the emission layer

6. light-emitting layer or system of several light-emitting layers, e.g. Emitter admixed CBP (carbazole derivatives) (e.g., phosphorescent triplet emitter iridium-tris-phenylpyridine Ir (ppy) 3) or Alq3 (tris-quinolinato-aluminum) mixed with emitter molecules (e.g., fluorescent singlet emitter qoumarin),

7. electron-side blocking layer to prevent exciton diffusion from the emission layer and to prevent carrier leakage from the emission layer, e.g. BCP (Bathocuproine),

8. Electron Transport Layer (ETL), e.g. BPhen, Alq3 (tris-quinolinato-aluminum),

10. Electrode, usually a low work function metal, electron injecting (cathode = negative pole), e.g. Aluminum.

Of course, layers can be left out or a layer (or material) can take on several properties, e.g. For example, layers 3-5 and layers 7 and 8 can be combined. Other layers can be used. Stacked OLEDs are also provided.

This design describes the non-inverted (anode on the substrate), substrate-emitting (bottom-emission) structure of an OLED. There are various concepts to describe emitting OLEDs away from the substrate (see references in DE10215210.1), all in common that then the substrate side electrode (in the non-inverted case, the anode) is reflective (or transparent to a transparent OLED) and the cover electrode (semi-) transparent. If the order of the layers is inverted (cathode on substrate) one speaks of inverted OLEDs (see references in DE101 35 513.0). Again, without special measures to be expected performance losses.

A preferred design of the structure of an OLED according to the invention is the inverted structure (where the cathode is on the substrate) and wherein the light is emitted through the substrate. Furthermore, it is preferred that the OLED Top is emitting.

The typical structure of an organic solar cell can look like this:

1. support, substrate, e.g. Glass

2. Anode, preferably transparent, e.g. Indium Tin Oxide (ITO)

Third hole layer,

5. hole-side intermediate layer, preferably block layer in order to prevent exciton diffusion from the absorption layer (optical active layer, also called emission layer) and to prevent charge carrier leakage from the emission layer,

6. Optical active layer (absorption layer), typically a strongly light-absorbing layer of a heterojunction (two or more layers or mixed layer) e.g. Mixed layer of C60 and ZnPc,

7. electron transport layer,

10. Cathode, eg aluminum. Of course, layers can be left out or a layer can take over several properties. Other layers can be used. Stacked (tandem) solar cells are provided. Variants such as transparent solar cells, inverted structure or mip solar cells are also possible. A preferred configuration of the structure of a solar cell is the inverted structure (where the cathode is on the substrate) and wherein the light is incident through the substrate.

embodiments

The invention will be explained in more detail in some embodiments. Synthesis of the 3-Radial Compounds To a solution of 207 mmol starting material (ae) and 250 mmol potassium carbonate in 370 ml dimethylformamide, a solution of 207 mmol cyanoacetic ester in 50 ml dimethylformamide was added dropwise with stirring. This mixture was stirred at room temperature for 48 h. Subsequently, the mixture was added to 1 liter of ice water. The solution was stirred vigorously and treated with 100 ml of concentrated acetic acid. This aqueous solution was then extracted four times with chloroform. The combined organic phases were completely evaporated after drying with magnesium sulfate in vacuo. The crude product was used without further purification in the next synthesis.

The total amount of aryl cyanoacetic ester (fj) was refluxed in 84 ml of acetic acid (50%) along with 4.15 ml of concentrated sulfuric acid for 16 h. After cooling, the entire amount was added to 120 ml of ice water and stirred for 30 min. The phases were separated and the aqueous phase extracted with 100 ml of chloroform. The United organic phases were washed with 100 ml of water and then with 100 ml of saturated sodium bicarbonate solution. After drying with magnesium sulfate and removal of the solvent was obtained after distillation in vacuo colorless oils (ko).

Lithium hydride (98%) was suspended in 600 ml of glyme and cooled to 0 ° C. 152 mmol of the arylacetonitrile (k-o) were slowly added dropwise in 60 ml of glyme. The ice bath was removed and the mixture was allowed to warm to room temperature. After stirring for 15 min at room temperature, the mixture was cooled again to 0.degree. C. and 40.0 mmol of tetrachlorocyclopropene in 40 ml of glyme were slowly added dropwise. After warming to room temperature, stirring was continued for a further 44 h. The mixture was then added to 1.2 l of ice-water and acidified with hydrochloric acid (pH = 1). The aqueous solution was extracted by shaking three times with 500 ml of ethyl acetate each time and the combined organic phases were washed first with saturated brine, then with water, then with sodium bicarbonate solution and finally with water again. It was dried with magnesium sulfate and the solvent removed in vacuo. The remaining dark brown oil was used without further purification in the next synthesis.

The material was dissolved in 1.4 1 of glacial acetic acid and treated dropwise with stirring with a previously prepared mixture of 360 ml of hydrobromic acid (48%) and 120 ml of nitric acid (65%). It was stirred for 1.5 h and then filtered. The red solid was washed with water, dried in vacuo and then purified by gradient sublimation (p-t).

Starting material Arylcyanessigester

Hexafluorobenzene (a) (f) Ethyl 2-cyano-2- (perfluorophenyl) acetate Pentafluoropyridine (b) (g) Ethyl 2-cyano-2- (perfluoropyridin-4-yl) acetate

Pentafluorobenzonitrile (c) (h) Ethyl 2-cyano-2- (4-cyano-perfluorophenyl) -acetate

Octafluorotoluene (d) (i) Ethyl 2-cyano-2- (4-trifluoromethylperfluorophenyl) acetate

4-trifluoromethyl-2,6-dichloro (j) ethyl 2-cyano-2- (4-trifluoromethyl-2,6-dichloro-3,5-1,3,5-trifluorobenzene (e) difluorophenyl) acetate

Intermediates, aryl end products, [3] radials

acetonitrile was

(k) pentafluorophenyl acetonitrile (p) (2E, 2'E, 2 "E) ^-2,2, 2" - (1,2,3-cyclopropane triyliden) tris (2- (perfluorophenyl) acetonitrile)

(1) 4- (cyanomethyl) -2, 3,5,6 (q) (2E, 2'E, 2 "E) ^-2,2, 2" - (1,2,3-cyclopropane-tetrafluoropyridine triylidenetris (2- (perfluoropyridine-4-yl) acetonitrile)

(m) 4- (cyanomethyl) -2, 3,5,6- (r) (2E, 2 ^, E, 2 "E) -2,2 ', 2" - (cyclopropane-1,2,3-triylidene tris (2-tetrafluorobenzonitrile (4-cyanoperfluorophenyl) acetonitrile)

(n) 2- (2,3,5,6-tetrafluoro-4- (s) (2E, 2'E, 2 "E) ^-2,2, 2" - (cyclopropane-l, 2,3- triylidene) tris (2- (trifluoromethyl) phenyl) - acetonitrile (2,3,5,6-tetrafluoro-4- (trifluoromethyl) phenyl) acetonitrile)

(o) (4-trifluoromethyl-2,6- (t) (2E, 2'E, 2 "E) ^-2,2, 2" - (cyclopropane-l, 2,3-triyliden) tris (2- dichloro-3,5-difluorophenyl) (2,6-dichloro-3,5-difluoro-4- (trifluoromethyl) phenyl) acetonitrile acetonitrile)

Synthesis of HTM

Example HTM of the formula 2

In a 0.5 liter round bottom flask, 70 g (0.14 mol) of 4,4 "-diiododiphenyl, 140 g (0.44 mol) of bis (biphenylyl) -amine, 45 g of potassium carbonate, 220 ml of Marlotherm It is heated to 110 ° C. and 20 g of copper catalyst are added, and the mixture is heated to a temperature of about 195 ° C. over 3.5 hours The mixture is cooled to 90 ° C. and filtered with suction to remove inorganic constituents, 100 ml of methanol are added, and the product is filtered off with suction through a suction filter.The product was then recrystallised from 2 l of dimethylformamide this was washed with 200 ml of methanol to remove occluded dimethylformamide.

After drying at 100 ° C, 83 g of products are recovered.

HTM glass point T _G HTM of Formula 2 141 ° C

HTM of Formula 3 146 ° C

HTM of Formula 4 143 ° C

HTM of Formula 5 168 ° C

measurement methods

The conductivity of a thin-film sample is measured by the 2-point method. In this case, contacts made of a conductive material are applied to a substrate, e.g. Gold or indium tin oxide. Thereafter, the thin film to be examined is applied over a large area to the substrate, so that the contacts are covered by the thin film. After applying a voltage to the contacts, the current then flowing is measured. From the geometry of the contacts and the layer thickness of the sample results from the thus determined resistance, the conductivity of the thin-film material. The 2-point method is permissible if the resistance of the thin film is significantly greater than the resistance of the leads or the contact resistance. Experimentally, this is ensured by a sufficiently high contact distance, and thereby the linearity of the current-voltage characteristic can be checked.

The temperature stability can be determined by the same method or the same structure by the (undoped or doped) layer heated gradually and after a rest period, the conductivity is measured. The maximum temperature that the layer can withstand without losing the desired semiconductor property, then the temperature is just before the conductivity breaks down. For example, a doped layer may be heated on a substrate with two adjacent electrodes as described above in 1 ° C increments, with 10 seconds left after each step. Then the conductivity is measured. The conductivity changes with the temperature and abruptly breaks down at a certain temperature. The temperature stability therefore indicates the temperature up to which the conductivity does not abruptly break.

doping concentration

Preferably, the dopant is present in a doping concentration of <1: 1 to the matrix molecule or the monomeric unit of a polymeric matrix molecule, preferably in a doping concentration of 1: 2 or less, more preferably from 1: 5 or less or 1: 10 or smaller , The doping concentration may be limited in the range of 1: 5 to 1: 10,000.

Implementation of the Doping The doping of the respective matrix material with the p-dopants to be used according to the invention can be produced by one or a combination of the following methods: a) mixed evaporation in vacuo with a source for the matrix material and one for the dopant. b) doping of a matrix layer by a solution of p-dopants with subsequent evaporation of the solvent, in particular by thermal

treatment c) Surface doping of a matrix material layer by a superficially applied layer of dopants d) Preparation of a solution of matrix molecules and dopants and subsequent production of a layer from this solution by conventional methods such as evaporation of the solvent or spin coating

In this way, according to the invention, it is therefore possible to produce p-doped layers of organic semiconductors which can be used in a variety of ways.

conductivity measurements

Doped Semiconductor Layer - Example 1: A 50 nm thick layer of HTM of Formula 2 was doped with compound (p). The doped layer was prepared by mixed evaporation of the HTM of formula 2 and the dopant (p) under high vacuum. The concentration of dopant in the matrix was 3 mol%. The evaporation temperature of the dopant was 372 ° C. The doped layer showed a high conductivity of 6-10 ^"4 S / cm. The temperature stability of the layer was 133 ° C.

Components: Example 1:

A layer of HTM of formula 2 was doped with compound (p). The doped layer was deposited on a ITO coated glass substrate by coevaporation of the HTM of Formula 2 and the dopant (p) under high vacuum. The concentration of dopant in the matrix was 1.5; 3.0; 4.5 wt%. As an additional reference, an a NPD layer doped with 3 wt% of compound (p) deposited on the same substrate. Subsequently, a layer of a-NPD, a fluorescent blue emitter layer, an undoped ETL and block layer, an n: doped electron transport layer and an aluminum cathode were deposited without interruption of the vacuum. Subsequently, the thus processed components were encapsulated against water with a lidded glass - a corresponding getter was previously introduced.

This results in the glass substrate emitting blue OLEDs whose characteristics are summarized in the table below.

HTL: Voltage / Current Efficiency Power Quantum Effi Lifetime Lifetime Density Efficiency ciency / h / h g with (p) [at 10 (cd / A) / (lm / W) /% [at [at

mA / cm ² ] [at 1000 [at 1000 [at 1000 30 mA / cm ² ] 60 mA / cm ² ] cd / m ² ] cd / m ² ] cd / m ² ]

HTM's 3.21 11.12 10.93 6.64 497 225

Formula 2,

1.5 wt%

HTM of 3.2 10.85 10.72 6.48 556 252

Formula 2,

3.0 wt%

HTM of 3.18 10.5 10.41 6.33 547 262

Formula 2,

4.5 wt% a-NPD, 3.26 10.52 10.18 6.51 476 225

3.0 wt%

As can be seen from the table, the operating voltage is improved when using HTM of formula 2 relative to a-NPD. This lower initial voltage then leads to better Efficiencies. For example, the power efficiency improves from 10.18 for the reference to 10.72 lm / W using HTM of Formula 2, both of which, HTM of Formula 2 and a-NPD, have been doped with 3 wt% (p) , The improvement in efficiency is thus over 5%. Another important performance parameter of OLED devices is the lifetime defined as the time that the initial brightness has dropped to half at a given current density. As can be seen from the table, one does not have to accept any losses when using HTM of formula 2 relative to a-NPD. On the contrary, in the above example with 3 wt% electrical doping, the lifetime at 30 mA / cm ² improves from 476 to 556h, or more than 15%. Example 2

A layer of HTM of formula 2 was doped with compound (p). The doped layer was deposited on a ITO coated glass substrate by coevaporation of the HTM of Formula 2 and the dopant (p) under high vacuum. The concentration of dopant in the matrix was 3.0 wt%. As a reference, an a-NPD layer doped with 3 wt% of compound (p) was also deposited on the same substrate. Subsequently, either a layer of a-NPD or a layer of HTM of formula 2 was deposited without interruption of the vacuum. The device was completed by a fluorescent red emitter layer, an undoped ETL and block layer, an n: doped electron transport layer and an aluminum cathode. Subsequently, the thus processed components were encapsulated against water with a lidded glass - a corresponding getter was previously introduced.

This results in the glass substrate emitting red OLEDs whose characteristics are summarized in the table below. HTL: Undoped HTL Voltage / V Power Efficiency Quantum Efficiency

Doping with (p) [at nz /%

10 mA / cm ² ] / (lm / W) [at 10000 cd / m ² ]

[at 10000

cd / m ² ]

HTM the

HTM of Formula 2 Formula 2 2.68 8.4 7.0

HTM of Formula 2 a-NPD 2.70 7.1 6.2

HTM the

a-NPD Formula 2 2.73 8.5 7.2 a-NPD a-NPD 2.69 7.8 6.5

As can be seen from the table, the efficiency of the red OLED improves markedly when using HTM of formula 2 as doped and as undoped layer relative to a reference OLED where both of these layers consist of the standard material a-NPD. In this specific case, the power efficiency improves, for example, from 7.8 to 8.4 lm / W, ie by about 8%.

Example 3: Another component example is intended to represent the superior temperature stability of the doped semiconductor layers. For this purpose, a 30 nm thick layer HTM of formula 3, HTM of formula 4 and HTM of formula 5 were processed on ITO Glass. In addition, a reference layer of 30 nm NPD. All of these materials were electrically doped with (p) 3% by co-evaporation. As a series resistor, a uniform 50 nm thick layer of highly stable hole transporting material TBRb (TertButylRubrene) was evaporated on all these layers. The hole transporting devices were terminated with a common 100 nm thick aluminum electrode. Subsequently, the thus processed components were encapsulated against water with a lidded glass - a corresponding getter was previously introduced.

The current-voltage characteristics of the device thus obtained were measured. Thereafter, for the purpose of estimating the temperature stability, all the OLEDs were heated to 120 ° C. in an oven for one hour. After cooling to room temperature, the current-voltage characteristics were measured again. The diode characteristics thus obtained are shown in Figure 2, wherein (21) HTM of formula 5, (22) HTM of formula 4, (23) HTM of formula 3 and (24) show the I-V data of a-NPD.

The characteristics can be roughly subdivided into desired forward currents for voltages greater than 1 V and parasitic leakage currents for voltages of less than 1 V. 1V in this case is the turn-on voltage of the device. Clearly recognizable, the a-NPD device already after processing significantly higher leakage currents relative to the materials according to the invention, HTM of formula 2, HTM of formula 3, HTM of formula 4 and HTM of formula 5. The difference, for example at -5 V, is about 2 orders of magnitude. The problem of parasitic leakage increases further for a-NPD after heating. Here, the leakage currents at -5 V reach almost 10 mA / cm ² . In contrast, components which use hole transport layers in the context of the invention behave much more tolerant of increasing temperature, and are at -5 V by more than five Orders of magnitude lower than the reference value of a-NPD at about 0.0001 mA / cm ² . The example demonstrates that it is possible to realize significantly temperature-stable organic components with hole transport materials in the context of the invention than with the standard hole transport material a-NPD. Example 4:

Four layers consisting of HTM (see table below) were doped with compound (p). The doped layers were deposited by co-evaporation with the dopant (p) in a high vacuum on an ITO coated glass substrate. The concentration of dopant in the matrix was 3.0 wt% in each of the four cases. As a reference, an a-NPD layer doped with 3 wt% of compound (p) was also deposited on the same substrate. Subsequently, without interruption of the vacuum, a layer of a-NPD, a red, a yellow, a blue and a green emitting layer, an undoped ETL and block layer, an n-doped electron transport layer and an aluminum cathode were deposited. Subsequently, the thus processed components were encapsulated against water with a lidded glass - a corresponding getter was previously introduced.

The processed OLED emits warm white light with color coordinates of (0.39, 0.40). The corresponding characteristics are summarized in the following table.

HTL: doping voltage power efficiency Quantum efficiency lifetime with 3wt% (p) / V / (lm / W) /% at 85 ° C

[at 10 [at 1000 cd / m ² ] [1000 cd / m ² ] / h

mA / cm ² ] [at

30 mA / cm ² ] HTM of Formula 2 3.1 16 6.6 120

HTM of Formula 3 3.18 15.81 6.49 82

HTM of Formula 4 3.3 14.23 6.26 86

HTM of Formula 5 3.34 13.5 6.19 100 a-NPD 3.09 15.6 6.36 74

As can be seen from the table, the initial efficiency of the components when using a hole transport layer in the sense of the invention is somewhat better, in part slightly worse, relative to the standard hole transport material a-NPD. On the other hand, there are significant improvements in component life as defined above at 85 ° C. The latter is improved by up to 35%, for example when using Formula 5 HTM.

Claims

claims

Organic semiconductor layer comprising at least one matrix material and at least one doping material, characterized in that the doping material is selected from compounds of formula (1)

Formula 1)

wherein R 1 is independently selected from aryl and heteroaryl, wherein aryl and heteroaryl are substituted with at least one electron-deficient substituent, preferably are fully substituted, and that the matrix material is selected from compounds of formula (2)

Formula (2)

or compounds of formula (2) wherein at least one H of formula (2) is substituted by aromatics and / or heteroaromatics and / or C1-C20 alkyl.

2. Organic semiconductor layer according to claim 1, characterized in that the dopant is incorporated in the matrix material.

3. Organic semiconductor layer according to claim 1, characterized in that the

Dotand and the matrix material form two layers that are in touching contact.

4. Organic semiconductor layer according to one of the preceding claims, characterized in that the doping material is selected from:

2,2 ', 2 "- (cyclopropane-l, 2,3-triylidene) tris (2- (perfluorophenyl) acetonitrile); 2,2', 2" - (cyclopropane-1,2,3-triylidene tris (2 - (perfluoropyridine-4-yl) acetonitrile);

2,2 ', 2 "- (cyclopropane-l, 2,3-triyliden) tris (2- (4-cyanoperfluorphenyl) acetonitrile);

2,2 ', 2 "- (cyclopropane-l, 2,3-triylidene) tris (2- (2,3,5,6-tetrafluoro-4- (trifluoromethyl) phenyl) -acetonitrile);

(Cyclopropane-1,2,3-triylidene) tris (2- (2,6-dicm

acetonitrile).

5. Organic component comprising an organic semiconductor layer according to one of the preceding claims.

6. Organic component according to claim 5, characterized in that it is a light-emitting component.

7. Organic component according to claim 5, characterized in that it is an organic solar cell.

8. Organic component according to claim 7, characterized in that the anode is closer to the substrate than the cathode.

9. Organic component according to claim 8, characterized in that the anode is transparent, and that the substrate and / or the anode are reflective.

10. Mixture comprising at least one matrix material and at least one doping material for producing a doped semiconductor layer, characterized in that the doping material is selected from compounds of the formula (1)

Formula 1)

wherein R 1 is independently selected from aryl and heteroaryl, wherein aryl and heteroaryl are substituted with at least one electron-deficient substituent, preferably fully substituted, and that the matrix material is selected from compounds of the formula (2)

wherein either X is methyl or tert-butyl and Y is selected from substituted or unsubstituted tetraphenylmethane or substituted or unsubstituted phenanthrene, preferably wherein Y is selected from:

or where X = phenyl and Y = biphenyl

11. Mixture according to claim 10, wherein the matrix material N4, N4, N4 ", N4" tetra ([l, l'biphenyl] -4-yl) - [1, Γ: 4 ', 1 "-terphenyl] -4 , 4 "-diamine is.

12. Mixture according to claim 10, wherein the doping material is selected from:

2,2 ', 2 "- (cyclopropane-l, 2,3-triyliden) tris (2- (perfluorophenyl) acetonitrile);

2,2 ', 2 "- (cyclopropane-l, 2,3-triylidentris (2- (perfluoropyridine-4-yl) acetonitrile);

(Cyclopropane, 2,3-triylidene) tris (2- (2,6-dicm

acetonitrile).