High efficiency transparent organic light emitting devices

• US 6,885,149 B2
• Filed: 10/28/2003
• Issued: 04/26/2005
• Est. Priority Date: 02/28/2000
• Status: Expired due to Term

• Current Assignee: The Trustees of Princeton University (Princeton University)
• Original Assignee: The Trustees of Princeton University (Princeton University)
• Inventors: Parthasarathy, Gautam, Burrows, Paul E., Forrest, Stephen R., Adachi, Chihaya
• Primary Examiner(s): Williams, Joseph
• Assistant Examiner(s): Roy, Sikha
• Application Number:
  US10/696,286
• Publication Number:
  US 20040085016A1
• Time in Patent Office: 546 Days
• Field of Search: 313/504, 313/503, 313506-511, 428/690, 428/691, 428/917, 445/23, 445/24, 427/66, 427/69, 427/70
• US Class Current: 313/504
• CPC Class Codes: A61B 18/00 Surgical instruments, devices or methods for transferring non-mechanical forms of energy to or from the body eye surgery A61F9/007; ear surgery A61F11/00
• CPC Class Codes: A61B 2017/00084 Temperature
• CPC Class Codes: A61B 2017/22051 with an inflatable part, e.g. balloon, for positioning, blocking, or immobilisation A61B2017/22048, A61B2017/3486 take precedence
• CPC Class Codes: A61B 2018/00095 high, i.e. heat conducting
• CPC Class Codes: A61F 2007/126 for invasive application, e.g. for introducing into blood vessels
• CPC Class Codes: A61F 7/123 using a flexible balloon containing the thermal element
• CPC Class Codes: A61M 2025/1072 having balloons with two or more compartments
• CPC Class Codes: A61M 2025/1086 having a special balloon surface topography, e.g. pores, protuberances, spikes or grooves
• CPC Class Codes: A61M 25/00 Catheters; Hollow probes dilators A61M29/00; peritoneal catheters A61M1/285; tracheal tubes A61M16/04; for drainage A61M27/00; for uterus, vagina or rectum A61M31/00 ; for measuring or testing A61B; materials for catheters A61L29/00
• CPC Class Codes: A61M 25/1011 Multiple balloon catheters
• CPC Class Codes: H10K 2102/3031 Two-side emission, e.g. transparent OLEDs [TOLED]
• CPC Class Codes: H10K 2102/351 Thickness
• CPC Class Codes: H10K 50/165 comprising dopants
• CPC Class Codes: H10K 50/171 Electron injection layers
• CPC Class Codes: H10K 50/18 Carrier blocking layers
• CPC Class Codes: H10K 50/828 Transparent cathodes, e.g. comprising thin metal layers
• CPC Class Codes: H10K 85/311 Phthalocyanine
• CPC Class Codes: H10K 85/324 comprising aluminium, e.g. Alq3

Abstract

A highly transparent non-metallic cathode is disclosed that comprises a metal-doped organic electron injection layer that is in direct contact with a transparent non-metallic electron injecting cathode layer, such as indium tin oxide (ITO), wherein the metal-doped organic electron injection layer also functions as an exciton blocking or hole blocking layer. The metal-doped organic electron injection layer is created by diffusing an ultra-thin layer of about 5-10 Å of a highly electropositive metal such as Li throughout the layer. A representative embodiment of the highly transparent non-metallic cathode comprises a layer of ITO, a layer of 2,9-dimethyl-4,7-diphenyl-1,10-phenanthroline (BCP), which acts as an electron injection, exciton blocking, and hole blocking layer, and an ultra-thin layer of lithium, which degenerately dopes the layer of BCP, improving the electron injecting properties of the BCP layer. This cathode is demonstrated for use in an OLED having a transparency of about 90% or higher combined with a device external quantum efficiency of about 1% or higher.

Claims

1. A method for fabricating a highly transparent and highly efficient organic light emitting device comprising:

preparing, in sequence on a substrate, an anode, an organic hole transporting layer, an organic electron transporting layer, a transparent electron injection layer, and a transparent, non-metallic, electron injecting cathode layer, wherein said transparent electron injection layer is a material selected from the group consisting of a material which acts as a hole blocking layer, a material which acts as an exciton blocking material and a material which acts as a combination hole and exciton blocking material; and

wherein said preparing includes the step of doping said transparent electron injection layer with a metal to form a metal-doped transparent electron injection layer.

2. The method according to claim 1 wherein said transparent electron injection layer is doped with said metal by depositing an ultra-thin layer of said metal on said organic electron transporting layer prior to depositing said transparent electron injection layer.

3. The method according to claim 1 wherein said transparent, non-metallic, electron injecting cathode layer is doped with said metal by depositing an ultra-thin layer of said metal on said transparent electron injection layer prior to depositing said transparent electron, injecting layer.

4. The method according to claim 1 wherein said transparent, non-metallic electron injecting cathode layer comprises ITO.

5. The method according to claim 2 wherein said ultra-thin layer of said metal has a thickness of 5-10 Å

.

6. The method according to claim 2, wherein said metal comprises a metal selected from the group consisting of Li, Sr and Sm.

7. The method according to claim 2, wherein said metal comprises Li.

8. The method according to claim 1, wherein said metal-doped transparent electron injection layer comprises 2,9-dimethyl-4,7-diphenyl-1,10-phenanthroline.

9. The method according to claim 1, wherein said metal-doped transparent electron injection layer has a metal atom density sufficient to produce an electronic density of at least about 10¹⁵/cm³.

10. The method according to claim 1, wherein said metal-doped transparent electron injection layer has a metal atom density sufficient to produce an electronic density of at least about 10²¹/cm³.

11. The method according to claim 1, wherein said metal-doped transparent electron injection layer has a metal atom density sufficient to produce a total external quantum efficiency of at least 1% for said organic light emitting device.

12. The method according to claim 1, wherein said hole transporting layer comprises 4,4-bis[N-(1 -naphthyl)-N-phenyl-amino] biphenyl.

13. The method according to claim 1, wherein said electron transporting layer comprises tris-(8-hydroxyquinoline) aluminum.