# US 7,608,856 B2 · Electronic devices comprising organic semiconductors

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- Number: US 7,608,856 B2
- Document ID: US7608856B2
- Status: Granted
- Kind: B2
- Application number: 11/587,462
- Filed: 2005-05-03
- Published: 2007-09-27
- Granted: 2009-10-27
- Earliest claimed: 2004-05-03
- Assignees: Merck Patent GmbH
- Inventors: Heinrich Becker; Reinhard Strey; Klaus Meerholz; David Christoph Müller
- Web page: https://patentgrep.com/patent/US7608856B2

## CPC

- H10K 85/631: {Amine compounds having at least two aryl rest on at least one amine-nitrogen atom, e.g. triphenylamine}
- H10K 50/85: Arrangements for extracting light from the devices
- Y02E 10/549: Organic PV cells
- H10K: ORGANIC ELECTRIC SOLID-STATE DEVICES
- Y02E: REDUCTION OF GREENHOUSE GAS [GHG] EMISSIONS, RELATED TO ENERGY GENERATION, TRANSMISSION OR DISTRIBUTION

## Abstract

The present invention describes organic electronic devices in which at least one organic layer of low refractive index is introduced. The light output of the electronic devices is thereby improved.

## Claims

### Claim 1

An organic electronic device comprising cathode and anode, at least one of which is transparent, and at least one layer comprising at least one organic semi-conductor, characterised in that at least one organic buffer layer which has a low refractive index is introduced between the transparent electrode and the layer which comprises the organic semiconductor and said buffer layer has a refractive index n<1.5.

### Claim 2 (depends on 1)

Organic electronic device according to claim 1, characterised in that the refractive index n of the buffer layer is between 1.2 and 1.4.

### Claim 3 (depends on 1)

Organic electronic device according to claim 1, wherein the organic electronic device is an organic or polymeric light-emitting diode, an organic solar cell, an organic optical detector, an organic laser diode, a field-quenching device or an organic optical amplifier.

### Claim 4 (depends on 1)

Organic electronic device according to claim 1, wherein the cathode is made of metals, metal alloys or multilayered structures with various metals, at least one of which has a low work function.

### Claim 5 (depends on 1)

Organic electronic device according to claim 1, wherein the anode has a potential of greater than 4.5 eV vs. vacuum.

### Claim 6 (depends on 5)

Organic electronic device according to claim 5, characterised in that a mixed metal oxide is used as anode.

### Claim 7 (depends on 1)

Organic electronic device according to claim 1, wherein the organic semiconductor is low-molecular-weight, oligomeric, dendritic or polymeric.

### Claim 8 (depends on 1)

Organic electronic device according to claim 1, wherein the total layer thickness of the organic semiconductor(s) is 10-300 nm.

### Claim 9 (depends on 1)

Organic electronic device according to claim 1, wherein a hole-injection layer is used on the anode.

### Claim 10 (depends on 2)

Organic electronic device according to claim 2, wherein the layer thickness of the buffer layer is in the range 50-1000 nm.

### Claim 11 (depends on 1)

Organic electronic device according to claim 1, wherein the layer of low refractive index is produced through the use of compounds of low refractive index.

### Claim 12 (depends on 2)

Organic electronic device according to claim 2, wherein the organic buffer layer of low refractive index is a porous layer whose pore size is in the nanometer region.

### Claim 13 (depends on 12)

Organic electronic device according to claim 12, characterised in that the pores of the buffer layer are closed.

### Claim 14

An organic electronic device comprising cathode and anode, at least one of which is transparent, and at least one layer comprising at least one organic semi-conductor, characterised in that at least one organic buffer layer which has a low refractive index is introduced between the transparent electrode and the layer which comprises the organic semiconductor and the buffer layer is open-pored, and the surface is thermally sealed.

### Claim 15 (depends on 12)

Organic electronic device according to claim 12, wherein the pore size of the layer is in an order of magnitude of 5 to 500 nm.

### Claim 16 (depends on 12)

Organic electronic device according to claim 12, wherein the porosity of the buffer layer is between 20 and 80%.

### Claim 17 (depends on 12)

Organic electronic device according to claim 12, wherein the porous layer is produced by means of porogens, which are removed from the layer after the layer formation.

### Claim 18 (depends on 12)

Organic electronic device according to claim 12, wherein the buffer layer is foamed.

### Claim 19 (depends on 18)

Organic electronic device according to claim 18, characterised in that the blowing agents used are compressed gases or low-boiling hydrocarbons.

### Claim 20 (depends on 18)

Organic electronic device according to claim 18, characterised in that the blowing agents used are supercritical fluids.

### Claim 21 (depends on 18)

Organic electronic device according to claim 18, characterised in that the buffer layer is foamed by means of chemical blowing agents.

### Claim 22 (depends on 18)

Organic electronic device according to claim 18, wherein finely dispersed solids of nanometer size are added as nucleation seeds.

### Claim 23 (depends on 18)

Organic electronic device according to claim 18, wherein emulsions are used.

### Claim 24 (depends on 23)

Organic electronic device according to claim 23, characterised in that micro-emulsions or finely divided emulsions are developed from a supercritical blowing agent in polymer.

### Claim 25

An organic electronic device comprising cathode and anode, at least one of which is transparent, and at least one layer comprising at least one organic semi-conductor, characterised in that at least one organic buffer layer which has a low refractive index is introduced between the transparent electrode and the layer which comprises the organic semiconductor and the organic buffer layer is crosslinked.

### Claim 26 (depends on 25)

Organic electronic device according to claim 25, characterised in that organic materials are used in which at least one H atom has been replaced by a group which reacts by cationic ring-opening polymerisation.

### Claim 27 (depends on 26)

Organic electronic device according to claim 26, characterised in that the crosslinking takes place via oxetane groups.

### Claim 28 (depends on 27)

Organic electronic device according to claim 27, characterised in that use is made in the buffer layer of low-molecular-weight, oligomeric, dendritic or polymeric organic semiconductors or conductors in which at least one H atom has been replaced by a group of the formula (1), formula (2), formula (3) or formula (4)
where
R1 is on each occurrence, identically or differently, H, a straight-chain, branched or cyclic alkyl, alkoxy or thioalkoxy group having 1 to 20 C atoms, an aromatic or heteroaromatic ring system having 5 to 24 aromatic ring atoms or an alkenyl group having 2 to 10 C atoms, in which one or more hydrogen atoms is optionally replaced by halogen or CN and one or more non-adjacent C atoms is optionally replaced by —O—, —S—, —CO—, —COO—, —O—CO—;
R2 is on each occurrence, identically or differently, H, a straight-chain, branched or cyclic alkyl group having 1 to 20 C atoms, an aromatic or heteroaromatic ring system having 5 to 24 aromatic ring atoms or an alkenyl group having 2 to 10 C atoms, in which one or more hydrogen atoms is optionally replaced by halogen or CN and one or more non-adjacent C atoms is optionally replaced by —O—, —S—, —CO—, —COO—, —O—CO—;
Z is on each occurrence, identically or differently, a divalent group —(CR3R4)n—, in which, in addition, one or more non-adjacent C atoms is optionally replaced by —O—, —S—, —CO—, —COO— or —O—CO—,
or a divalent aromatic or heteroaromatic ring system having 5 to 40 aromatic ring atoms, which is optionally substituted by one or more radicals R3;
R3, R4 are on each occurrence, identically or differently, hydrogen, a straight-chain, branched or cyclic alkyl, alkoxy or thioalkoxy group having 1 to 20 C atoms, an aryl or heteroaryl group having 5 to 20 aromatic ring atoms or an alkenyl group having 2 to 10 C atoms, in which, in addition, one or more hydrogen atoms is optionally replaced by halogen or CN; radicals R3 or 4 optionally forms a ring system here with one another or with R1 or R2;
n is on each occurrence, identically or differently, an integer between 0 and 30;
x is on each occurrence, identically or differently, an integer between 0 and 5,
with the proviso that the number of groups of the formula (1) or formula (2) or formula (3) or formula (4) is limited by the maximum number of available H atoms of the organic semiconductor or conductor; the dashed line here describes the link to the organic semiconductor or conductor.

### Claim 29 (depends on 25)

Organic electronic device according to claim 25, wherein the crosslinking is carried out during the foaming process.

### Claim 30 (depends on 25)

Organic electronic device according to claim 25, wherein the crosslinking is carried out after application and where appropriate conditioning of the layer and before the removal of the porogens.

### Claim 31 (depends on 2)

Organic electronic device according to claim 2, wherein the materials for the buffer layer are hole-conducting.

### Claim 32 (depends on 31)

Organic electronic device according to claim 31, characterised in that the materials for the buffer layer are doped.

### Claim 33

An organic electronic device comprising cathode and anode, at least one of which is transparent, and at least one layer comprising at least one organic semi-conductor, characterised in that at least one organic buffer layer which has a low refractive index is introduced between the transparent electrode and the layer which comprises the organic semiconductor and the materials for the buffer layer are doped materials based on triarylamine, based on thiophene, based on triaryiphosphine and/or based on pyrrole.

### Claim 34

An organic electronic device comprising cathode and anode, at least one of which is transparent, and at least one layer comprising at least one organic semi-conductor, characterised in that at least one organic buffer layer which has a low refractive index is introduced between the transparent electrode and the layer which comprises the organic semiconductor and the buffer layer is produced through the use of compounds having long alkyl chains and/or fluorinated compounds.

### Claim 35 (depends on 12)

Organic electronic device according to claim 12, characterised in that the buffer layer is open-pored, and the surface is thermally sealed by irradiation with a laser or by infrared irradiation.

### Claim 36 (depends on 1)

The organic electronic device as claimed in claim 1, wherein said buffer layer has a refractive index n<1.4.

### Claim 37 (depends on 1)

The organic electronic device as claimed in claim 1, wherein the device is an organic or polymeric light-emitting diode.