Stacked white OLED having separate red, green and blue sub-elements

• US 9,065,067 B2
• Filed: 05/27/2014
• Issued: 06/23/2015
• Est. Priority Date: 10/28/2008
• Status: Active Grant

• Current Assignee: Board of Regents of the University of Michigan (University of Michigan)
• Original Assignee: Board of Regents of the University of Michigan (University of Michigan)
• Inventors: Forrest, Stephen, Qi, Xiangfei, Slootsky, Michael
• Primary Examiner(s): Soward, Ida M
• Application Number:
  US14/287,272
• Publication Number:
  US 20140361271A1
• Time in Patent Office: 392 Days
• US Class Current: 1/1
• CPC Class Codes: H10K 2101/10 Triplet emission
• CPC Class Codes: H10K 2101/30 Highest occupied molecular orbital [HOMO], lowest unoccupied molecular orbital [LUMO] or Fermi energy values
• CPC Class Codes: H10K 2101/40 Interrelation of parameters between multiple constituent active layers or sublayers, e.g. HOMO values in adjacent layers
• CPC Class Codes: H10K 2102/00 Constructional details relating to the organic devices covered by this subclass
• CPC Class Codes: H10K 2102/103 comprising indium oxides, e.g. ITO
• CPC Class Codes: H10K 50/11 characterised by the electroluminescent [EL] layers
• CPC Class Codes: H10K 50/125 specially adapted for multicolour light emission, e.g. for emitting white light
• CPC Class Codes: H10K 50/13 comprising stacked EL layers within one EL unit
• CPC Class Codes: H10K 50/19 Tandem OLEDs
• CPC Class Codes: H10K 59/30 Devices specially adapted for multicolour light emission
• CPC Class Codes: H10K 59/32 Stacked devices having two or more layers, each emitting at different wavelengths
• CPC Class Codes: H10K 59/35 comprising red-green-blue [RGB] subpixels

Abstract

The present invention relates to efficient organic light emitting devices (OLEDs). More specifically, the present invention relates to white-emitting OLEDs, or WOLEDs. The devices of the present invention employ three emissive sub-elements, typically emitting red, green and blue, to sufficiently cover the visible spectrum. The sub-elements are separated by charge generating layers.

Claims

1. An organic light emitting device comprising in order:

a cathode;

a blue-emitting sub-element comprising an emissive layer comprising a phosphorescent blue emissive material;

a charge-generating layer;

a green-emitting sub-element comprising an emissive layer comprising a phosphorescent green emissive material;

a charge-generating layer;

a red-emitting sub-element comprising an emissive layer comprising a phosphorescent red emissive material;

and an anode;

wherein a combined emission of the emissive materials gives a white emission from the device.

2. The organic light emitting device of claim 1, wherein each sub-element comprises a hole transporting layer, an electron transporting layer and the emissive layer, wherein the emissive layer is the hole transporting layer, the electron transporting layer or a separate layer.

3. The organic light emitting device of claim 1, wherein the device emits light having CIE coordinates of X=0.37±

0.08, and Y=0.37±

0.08.

4. The organic light emitting device of claim 1, wherein the device is capable of a maximum external quantum efficiency of at least about 30%.

5. The organic light emitting device of claim 1, wherein the charge-generating layers comprises an n-type layer adjacent to a p-type layer.

6. The organic light emitting device of claim 5, wherein the p-type layers comprise a material selected from MoO₃, V₂O₅, ITO, TiO₂, WO₃ and SnO₂.

7. The organic light emitting device of claim 6, wherein the p-type layers comprise MoO₃.

8. The organic light emitting device of claim 1, wherein the emissive layers of each subelement are within about 20% of the distance to an antinode for that emitter.

9. The organic light emitting device of claim 1, wherein at least two of the emissive layers are close enough to an antinode so as to provide at least 90% of its maximum emission.

10. The organic light emitting device of claim 9, wherein each of the emissive layers are close enough to an antinode so as to provide at least 90% of its maximum emission.