# US 10,483,478 B2 · Buffer assisted charge generation layer for tandem OLEDs

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- Number: US 10,483,478 B2
- Document ID: US10483478B2
- Status: Granted
- Kind: B2
- Application number: 15/908,502
- Filed: 2018-02-28
- Published: 2018-09-06
- Granted: 2019-11-19
- Earliest claimed: 2017-03-01
- Assignees: eMagin Corporation
- Applicants: eMagin Corporation
- Inventors: Qi Wang; Evan P. Donoghue; Ilyas I. Khayrullin; Tariq Ali; Kerry Tice; Amalkumar P. Ghosh
- Web page: https://patentgrep.com/patent/US10483478B2

## CPC

- H10K 50/19: Tandem OLEDs
- H10K 50/13: comprising stacked EL layers within one EL unit
- H10K 50/15: Hole transporting layers
- H10K 50/16: Electron transporting layers
- H10K 59/351: {comprising more than three subpixels, e.g. red-green-blue-white [RGBW]}
- H10K 59/12: Active-matrix OLED [AMOLED] displays
- H10K 59/35: comprising red-green-blue [RGB] subpixels
- H10K: ORGANIC ELECTRIC SOLID-STATE DEVICES

## Abstract

A tandem Organic Light Emitting Diode (OLED) apparatus and method of fabricating the same, where the tandem OLED apparatus includes a buffer assisted charge generation layer having a junction of a p-type doped semiconductor layer and an n-type doped semiconductor layer, where a hole buffer layer and an electron buffer layer pair surrounding the junction of the p-type and n-type doped semiconductor layers. The OLED apparatus further includes a first OLED emissive layer and a second OLED emissive layer pair surrounding the buffer assisted charge generation layer, and a cathode and anode layer pair further surrounding the first and second OLED emissive layer pair.

## Claims

### Claim 1

A tandem Organic Light Emitting Diode (OLED) apparatus comprising:
a buffer assisted charge generation layer including
a junction of a p-type doped semiconductor layer and an n-type doped semiconductor layer, and
a hole buffer layer and an electron buffer layer pair surrounding the junction of the p-type and n-type doped semiconductor layers;
a first OLED emissive layer and a second OLED emissive layer pair surrounding the buffer assisted charge generation layer; and
a cathode and anode layer pair surrounding the first and second OLED emissive layer pair;
wherein the hole buffer layer is between and adjacent to the p-type doped semiconductor layer and one of the first or second OLED emissive layers, and the electron buffer layer is between and adjacent to the n-type doped semiconductor layer and the other of the first or second OLED emissive layers.

### Claim 2 (depends on 1)

The apparatus according to claim 1, wherein at least one of the first or second OLED emissive layers comprises one of a red, green, blue or white light emission output.

### Claim 3 (depends on 1)

The apparatus according to claim 1, wherein the hole buffer layer is selected from at least one from the group comprising MoO3, WO3, Ag, HAT-CN and V2O5.

### Claim 4 (depends on 1)

The apparatus according to claim 1, wherein the electron buffer layer is selected from at least one from the group comprising LiF, LiQ, CsF, Cs2CO3, Ca, Li, Al or Mg.

### Claim 5 (depends on 1)

The apparatus according to claim 1, wherein the electron buffer layer is comprised of highly conductive one of organic, inorganic and metal materials, and
wherein the hole buffer layer is comprised of highly conductive one of p-type organic, inorganic and metal materials.

### Claim 6

An active matrix display comprising:
an array of organic light emitting diode (OLED) pixels, each of the OLED pixels including
a plurality of OLED sub-pixels, at least one of the OLED sub-pixels having a buffer assisted charge generation layer including
a junction of p-type doped semiconductor layer and an n-type doped semiconductor layer, and
a hole buffer layer and an electron buffer layer pair surrounding the junction of the p-type and n-type doped semiconductor layers;
a first OLED emissive layer and a second OLED emissive layer pair surrounding the buffer assisted charge generation layer; and
a cathode and anode layer pair surrounding the first and second OLED emissive layer pair; and
a driving circuit connected to and configured to provide an energizing signal to each of the plurality of sub-pixels of the array of OLED pixels within the active matrix display;
wherein the hole buffer layer is between and adjacent to the p-type doped semiconductor layer and one of the first or second OLED emissive layers, and the electron buffer layer is between and adjacent to the n-type doped semiconductor layer and the other of the first or second OLED emissive layers.

### Claim 7 (depends on 6)

The active matrix display according to claim 6, wherein each of the plurality of sub-pixels comprises one of a red, green, blue or white light emission output.

### Claim 8 (depends on 6)

The apparatus according to claim 6, wherein the hole buffer layer is selected from at least one from the group comprising MoO3, WO3, Ag, HAT-CN and V2O5.

### Claim 9 (depends on 6)

The apparatus according to claim 6, wherein the electron buffer layer is selected from at least one from the group comprising LiF, LiQ, CsF, Cs2CO3, Ca, Li, Al or Mg.

### Claim 10 (depends on 6)

The apparatus according to claim 6, wherein the electron buffer layer is comprised of highly conductive one of organic, inorganic and metal materials, and
wherein the hole buffer layer is comprised of highly conductive one of p-type organic, inorganic and metal materials.

### Claim 11

A method of fabricating an Organic Light Emitting Diode (OLED) matrix display, comprising:
forming an array of OLEDs pixels over a substrate, each pixel of the OLED array including a plurality of OLED sub-pixels, wherein at least one sub-pixel of the plurality of OLED subpixels include
a buffer assisted charge generation layer including
a p-type electrode layer adjacent an n-type electrode layer, and
a hole buffer layer and an electron buffer layer surrounding the coupled p-type and n-type electrode layers,
a first OLED emissive layer and a second OLED emissive layer pair surrounding the buffer assisted charge generation layer, and
a cathode and anode layer pair surrounding the first and second OLED emissive layers; and
providing a driving circuit connected to and configured to provide an energizing signal to each of the plurality of sub-pixels of the array of pixels within the active matrix display;
wherein the hole buffer layer is between and adjacent to the p-type doped semiconductor layer and one of the first or second OLED emissive layers, and the electron buffer layer is between and adjacent to the n-type doped semiconductor layer the other of the first or second OLED emissive layers.

### Claim 12 (depends on 11)

The method according to claim 11, further comprising:
providing each of the plurality of sub-pixels including one of a red, green, blue or white light emission output.

### Claim 13 (depends on 11)

The method according to claim 11, further comprising:
providing the hole buffer layer being selected from at least one from the group comprising MoO3, WO3, Ag, HAT-CN and V2O5.

### Claim 14 (depends on 11)

The method according to claim 11, further comprising:
providing the electron buffer layer being selected from at least one from the group comprising LiF, LiQ, CsF, Cs2CO3, Ca, Li, Al or Mg.