Electroluminescent device with improved cathode

• US 4,885,211 A
• Filed: 02/11/1987
• Issued: 12/05/1989
• Est. Priority Date: 02/11/1987
• Status: Expired due to Term

• Current Assignee: Eastman Kodak Company
• Original Assignee: Eastman Kodak Company
• Inventors: Tang, Ching W., VanSlyke, Steven A.
• Primary Examiner(s): NOT, DEFINED
• Assistant Examiner(s): Monroe, James B.
• Application Number:
  US07/013,530
• Time in Patent Office: 1,028 Days
• Field of Search: 313/346 R, 313/346 C, 313/498, 313/504, 313/506, 313/507, 252/301.16, 357/8, 428/411.1, 428/457, 428/461, 428/515, 428/917
• US Class Current: 428/457
• CPC Class Codes: C09K 11/06 containing organic luminescent materials
• CPC Class Codes: 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
• CPC Class Codes: H05B 33/26 characterised by the composition or arrangement of the conductive material used as an electrode
• CPC Class Codes: H05B 33/28 of translucent electrodes
• CPC Class Codes: H10K 50/82 Cathodes
• CPC Class Codes: H10K 85/311 Phthalocyanine
• CPC Class Codes: Y10S 428/917 Electroluminescent
• CPC Class Codes: Y10T 428/31504 Composite [nonstructural laminate]
• CPC Class Codes: Y10T 428/31678 Of metal
• CPC Class Codes: Y10T 428/31692 Next to addition polymer from unsaturated monomers
• CPC Class Codes: Y10T 428/31909 Next to second addition polymer from unsaturated monomers

Abstract

An electroluminescent device is disclosed comprised of, in sequence, an anode, an organic hole transporting zone, an organic electron transporting zone, and a cathode. The cathode is comprised of a layer of a plurality of metals other than alkali metals, at least one of said metals having a work function of less than 4 eV.

Claims

1. An electroluminescent device comprising in sequence, an anode, an organic hole transporting zone, an organic electron transporting zone, and a cathode, characterized in that

said cathode is comprised of a layer having a sheet resistance of less than 100 ohms per square consisting essentially of at least 50 percent magnesium and at least 0.1 percent of a metal having a work function greater than 4 eV, said metal percentages being based on total metal atoms present in said cathode layer.

2. An electroluminescent device according to claim 1 in which said organic hole transporting zone and said organic electron transporting zone together form an organic luminescent medium having a thickness of less than 1 micrometer.

3. An electroluminescent device according to claim 1 in which said organic electron transporting zone is formed of a stilbene or chelated oxinoid compound.

4. An electroluminescent device according to claim 3 in which said electron transporting zone is comprised of a vacuum vapor deposited stilbene or chelated oxinoid layer and said cathode layer is comprised of a mixture of magnesium and said high work function metal vacuum deposited on said electron transporting layer.

5. An electroluminescent device according to claim 1 in which said metal having a work function greater than 4 eV is present in said cathode layer in a concentration of from 1 to 20 percent of the total metal atoms present.

6. An electroluminescent device according to claim 1 in which said metal having a work function greater than 4 eV is a silver.

7. An electroluminescent device according to claim 1 in which said metal having a work function greater than 4 eV is aluminum.

8. An electroluminescent device according to claim 1 in which said metal having a work function greater than 4 eV is manganese.

9. An electroluminescent device according to claim 1 in which said metal having a work function greater than 4 eV is indium.

10. An electroluminescent device according to claim 1 in which said metal having a work function greater than 4 eV is tin.

11. An electroluminescent device according to claim 1 in which said metal having a work function greater than 4 eV is a copper.

12. An electroluminescent device according to claim 1 in which said metal having a work function greater than 4 eV is a gold.

13. An electroluminescent device according to claim 1 in which said metal having a work function greater than 4 eV is a Group VIII metal.

14. An electroluminescent device according to claim 13 in which said Group VIII metal is nickel.

15. An electroluminescent device according to claim 13 in which said Group VIII metal is a noble Group VIII metal.

16. An electroluminescent device according to claim 15 in which said noble Group VIII metal is palladium.

17. An electroluminescent device according to claim 1 in which said metal having a work function greater than 4 eV is chromium.

18. An electroluminescent device according to claim 1 in which said metal having a work function greater than 4 eV is antimony.

19. An electroluminescent device according to claim 1 in which said metal having a work function greater than 4 eV is tellurium.

20. An electroluminescent device comprising in sequence,

an opaque anode comprised of a metal having a work function greater than 4 eV,

an organic luminescent medium consisting of

an organic hole transporting zone and

a chelated oxinoid electron transporting zone, and

a light transmissive cathode consisting essentially of a vacuum vapor deposited layer having a thickness of from 50 to 250 Angstroms and a sheet resistance of less than 100 ohms per square consisting essentially of magnesium and silver,

said silver being present in a concentration of from 0.1 to 50 percent, based on total magnesium and silver atoms present.

21. An electroluminescent device according to claim 20 in which said silver is present in said cathode layer in a concentration of from 1 to 20 percent of the total metal atoms present.

22. An electroluminescent device according to claim 20 in which said organic luminescent medium has a thickness of less than 1 micrometer.

23. An electroluminescent device according to claim 20 in which said chelated oxinoid compound is aluminum trisoxine.