# US 2010/0167440 A1 · Light Emissive Device

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- Number: US 2010/0167440 A1
- Document ID: US20100167440A1
- Status: Published application
- Kind: A1
- Application number: 12/721,523
- Filed: 2010-03-10
- Published: 2010-07-01
- Earliest claimed: 2004-12-24
- Assignees: Cambridge Display Technology Limited
- Inventors: Matthew Roberts
- Web page: https://patentgrep.com/patent/US20100167440A1

## CPC

- C09K 11/06: containing organic luminescent materials
- H05B 33/14: characterised by the chemical or physical composition or the arrangement of the electroluminescent material {, or by the simultaneous addition of the electroluminescent material in or onto the light source}
- H10K 59/80524: {Transparent cathodes, e.g. comprising thin metal layers}
- C09K 2211/1011: Condensed systems
- C09K 2211/1014: bridged by heteroatoms, e.g. N, P, Si or B
- H10K 2102/3026: {Top emission}
- Y10T 428/31678: Of metal
- C09K: MATERIALS FOR MISCELLANEOUS APPLICATIONS, NOT PROVIDED FOR ELSEWHERE
- H05B: ELECTRIC HEATING; ELECTRIC LIGHT SOURCES NOT OTHERWISE PROVIDED FOR; CIRCUIT ARRANGEMENTS FOR ELECTRIC LIGHT SOURCES, IN GENERAL
- H10K: ORGANIC ELECTRIC SOLID-STATE DEVICES
- Y10T: TECHNICAL SUBJECTS COVERED BY FORMER US CLASSIFICATION

## Abstract

An organic light emissive device including a cathode; an anode; and an organic light emissive region between the cathode and the anode, wherein the cathode includes a transparent bilayer comprising a layer of a low work function metal having a work function of no more than 3.5 eV and a transparent layer of silver.

## Claims

### Claim 1

A process for the manufacture of an organic light emissive device comprising:
providing a device comprising an anode and an organic light emissive region;
forming a cathode comprising a transparent bilayer over the light emissive region by (i) depositing a layer of a low work function metal having a work function of no more than 3.5 eV over the light emissive region and (ii) depositing a transparent silver layer on the layer of low work function metal; and
depositing a transparent encapsulation layer over the bilayer in order to minimize exposure of the bilayer to oxygen and/or moisture.

### Claim 2 (depends on 1)

The process according to claim 1, wherein the low work function metal is an alkali metal or an alkaline earth metal.

### Claim 3 (depends on 1)

The process according to claim 1, wherein the low work function metal is barium.

### Claim 4 (depends on 1)

The process according to claim 1, wherein the bilayer has a thickness in the range of from 5 nm to 20 nm.

### Claim 5 (depends on 1)

The process according to claim 1, wherein the bilayer has a thickness in the range of from 5 nm to 10 nm.

### Claim 6 (depends on 1)

The process according to claim 1, wherein the layer of silver has a thickness in the range of from 2 nm to 18 nm.

### Claim 7 (depends on 1)

The process according to claim 1, wherein the device is a top-emitting device.

### Claim 8 (depends on 1)

The process according to claim 1, wherein the anode is reflective.

### Claim 9 (depends on 1)

The process according to claim 1, wherein the anode is provided on a substrate comprising a metal mirror.

### Claim 10 (depends on 1)

The process according to claim 1, wherein the substrate comprises an active matrix back plane.

### Claim 11 (depends on 1)

The process according to claim 1, wherein the organic light emissive region comprises subpixels of red, green and blue light emitting materials, and the cathode injects electrons into each subpixel.

### Claim 12 (depends on 1)

The process according to claim 1, wherein the organic light emissive region comprises a light emitting polymer or light emitting dendrimer.

### Claim 13 (depends on 1)

The process according to claim 1, wherein the bilayer has a transparency in the device of at least 60%.

### Claim 15 (depends on 1)

The process according to claim 1, wherein the bilayer has a transparency in the device of at least 65%.

### Claim 16 (depends on 1)

The process according to claim 1, wherein the layer of low work function metal consists essentially of the low work function metal having a work function of no more than 3.5 eV and the transparent silver layer consists essentially of silver.

### Claim 17

A process for the manufacture of an organic light emissive device comprising:
providing a device comprising an anode and an organic light emissive region;
forming a cathode comprising a transparent bilayer over the light emissive region by (i) depositing a layer of a low work function metal having a work function of no more than 3.5 eV over the light emissive region and (ii) depositing a transparent silver layer on the layer of low work function metal; and
depositing a transparent encapsulation layer over the bilayer in order to minimize exposure of the bilayer to oxygen and/or moisture,
wherein the layer of low work function metal consists essentially of the low work function metal having a work function of no more than 3.5 eV and the transparent silver layer consists essentially of silver and the bilayer has a transparency in the device of at least 60%.

### Claim 18 (depends on 17)

The process according to claim 17, wherein the low work function metal is an alkali metal or an alkaline earth metal.

### Claim 19 (depends on 17)

The process according to claim 17, wherein the low work function metal is barium.

### Claim 20 (depends on 17)

The process according to claim 17, wherein the bilayer has a thickness in the range of from 5 nm to 20 nm.