Light emitting device and method of fabricating the same

• US 20110175064A1
• Filed: 01/21/2010
• Published: 07/21/2011
• Est. Priority Date: 01/21/2010
• Status: Active Grant

• Current Assignee: Samsung Electronics Co. Ltd., Regents of the University of California (University of California)
• Original Assignee: Samsung Electronics Co. Ltd., Regents of the University of California (University of California)
• Inventors: Kim, Do-Hwan, Cho, Shinuk, Park, Sung Heum, Lee, Kwanghee, Lee, Jae-kwan, Lee, Sang-Yoon, Heeger, Alan J.
• Granted Patent: US 9,608,225 B2
• Time in Patent Office: Days
• US Class Current: 257/40
• CPC Class Codes: H10K 50/00 Organic light-emitting devices integrated devices or assemblies of multiple devices H10K59/00, H10K65/00; organic semiconductor lasers H01S5/36
• CPC Class Codes: H10K 50/125 specially adapted for multicolour light emission, e.g. for emitting white light
• CPC Class Codes: H10K 50/14 Carrier transporting layers
• CPC Class Codes: H10K 50/805 Electrodes
• CPC Class Codes: H10K 59/32 Stacked devices having two or more layers, each emitting at different wavelengths
• CPC Class Codes: H10K 59/805 Electrodes
• CPC Class Codes: H10K 71/00 Manufacture or treatment specially adapted for the organic devices covered by this subclass

Abstract

A light emitting device may include a first electrode on a substrate, a first emission layer on the first electrode, a buffer layer on the first emission layer, a middle electrode on the buffer layer, a second emission layer on the middle electrode, and a second electrode on the second emission layer. The buffer layer may include a material selected from the group consisting of a metal oxide, a polyelectrolyte, and a combination thereof. The first emission layer, buffer layer, middle electrode, and second emission layer may be fabricated using a wet process.

Claims

1. A light emitting device comprising:

a first electrode on a substrate;

a first emission layer on the first electrode;

a buffer layer on the first emission layer;

a middle electrode on the buffer layer;

a second emission layer on the middle electrode; and

a second electrode on the second emission layer,

wherein the buffer layer includes at least one of a metal oxide, a polyelectrolyte, and combinations thereof.

2. The light emitting device of claim 1, wherein the substrate includes a material selected from the group consisting of glass, quartz, silicon, a synthetic resin, a metal, and a combination thereof.

3. The light emitting device of claim 1, wherein the first electrode includes a material having a work function of about 4.3 eV to about 5.0 eV, and the second electrode includes a material having a work function of about 2.3 eV to about 2.7 eV.

4. The light emitting device of claim 1, wherein the middle electrode includes a material having a work function of about 4.3 eV to about 5.0 eV.

5. The light emitting device of claim 1, wherein the middle electrode includes a conductive polymer.

6. The light emitting device of claim 5, wherein the conductive polymer includes polythiophene, polyaniline, polypyrrole, polyacene (polyacene), polyphenylene, polyphenylenevinylene, a derivative thereof, a copolymer thereof, or a mixture thereof.

7. The light emitting device of claim 5, wherein the conductive polymer includes polypyrrole, poly(3-methylpyrrole), poly(3-butylpyrrole), poly(3-octylpyrrole), poly(3-decylpyrrole), poly(3,4-dimethylpyrrole), poly(3,4-dibutylpyrrole), poly(3-hydroxylpyrrole), poly(3-methyl-4-hydroxylpyrrole), poly(3-methoxypyrrole), poly(3-ethoxypyrrole), poly(3-octoxypyrrole), poly(3-carboxylpyrrole), poly(3-methyl-4-carboxylpyrrole), poly(N-methylpyrrole), polythiophene, poly(3-methylthiophene), poly(3-butylthiophene), poly(3-octylthiophene), poly(3-decylthiophene), poly(3-dodecylthiophene), poly(3-methoxythiophene), poly(3-ethoxythiophene), poly(3-octoxythiophene), poly(3-carboxylthiophene), poly(3-methyl-4-carboxylthiophene), poly(3,4-ethylenedioxythiophene), polyaniline, poly(2-methylaniline), poly(2-octylaniline), poly(2-isobutylaniline), poly(3-isobutylaniline), poly(2-anilinesulfonic acid), poly(3-anilinesulfonic acid), or a mixture thereof.

8. The light emitting device of claim 5, wherein the conductive polymer is doped with a dopant.

9. The light emitting device of claim 1, wherein the metal oxide includes a metal selected from titanium (Ti), zinc (Zn), strontium (Sr), indium (In), barium (Ba), potassium (K), niobium (Nb), iron (Fe), tantalum (Ta), tungsten (W), bismuth (Bi), nickel (Ni), copper (Cu), molybdenum (Mo), cerium (Ce), platinum (Pt), silver (Ag), rhodium (Rh), ruthenium (Ru), or a combination thereof.

10. The light emitting device of claim 1, wherein the polyelectrolyte includes a cationic polyelectrolyte, an anionic polyelectrolyte, a non-ionic polyelectrolyte, or a mixture thereof.

11. The light emitting device of claim 10, wherein the cationic polyelectrolyte is represented by one of the following Chemical Formulae 1 to 3:

12. The light emitting device of claim 10, wherein the cationic polyelectrolyte includes a fluorene alkyl ammonium salt, a poly(diallyldialkyl ammonium salt), a poly((meth)acryloyloxyalkyltrialkyl ammonium salt), poly((meth)acryloyloxyalkylaryldialkyl ammonium salt), poly(arylamine salt), poly(allylamine salt), poly(alkylene imine), poly((meth)acrylamide), poly(alkenyl amine), or a combination thereof.

13. The light emitting device of claim 10, wherein the anionic polyelectrolyte includes one selected from the group consisting of poly(styrene sulfonate) (PSS), poly(acrylic acid), poly(methacrylic acid), polymethyl(meth)acrylate, polymaleic acid, poly(alkylene oxide), poly(alkenyl sulfate), poly(alkenyl sulfonate), poly(3-sulfoalkyl(meth)acrylate), poly((meth)acrylamido-2-alkyl-alkanesulfonate, and a combination thereof.

14. The light emitting device of claim 1, wherein the polyelectrolyte has a weight average molecular weight of about 500 to about 20,000 g/mol.

15. The light emitting device of claim 1, further comprising:

a buffer layer between at least one of the first electrode and the first emission layer, and the second emission layer and the second electrode.

16. The light emitting device of claim 1, further comprising:

an electron transport layer (ETL) between at least one of the first electrode and the first light emitting layer, and the second light emitting layer and the second electrode.

17. The light emitting device of claim 1, further comprising:

a hole blocking layer (HBL) between at least one of the first electrode and the first emission layer, and the second electrode and the second emission layer.

18. A method of manufacturing a light-emitting device comprising:

providing a first electrode on a substrate;

providing a first emission layer on the first electrode;

providing a buffer layer on the first emission layer;

providing a middle electrode on the buffer layer;

providing a second emission layer on the middle electrode; and

providing a second electrode on the second emission layer,

wherein the first emission layer, the buffer layer, the middle electrode, and the second emission layer are made using a wet process.

19. The method of claim 18, wherein the wet process includes at least one of gravure printing, off-set printing, screen printing, inkjet printing, spin coating, spray coating, or combinations thereof.

20. The method of claim 18, wherein the buffer layer is formed by a sol-gel reaction of a metal oxide precursor with the first emission layer or by coating a composition including a polyelectrolyte on the first emission layer.