Organic light emitting diode color display

• US 6,395,328 B1
• Filed: 07/15/1999
• Issued: 05/28/2002
• Est. Priority Date: 04/10/1996
• Status: Expired due to Term

• Current Assignee: IPIFS Guarantee Corp.
• Original Assignee: Cambridge Display Technology Limited (Sumitomo Chemical Company Limited)
• Inventors: May, Paul
• Primary Examiner(s): YAMNITZKY, MARIE ROSE
• Application Number:
  US09/155,951
• Time in Patent Office: 1,048 Days
• Field of Search: 428/690,917,201,209,212 313/504,505,506,510 257/40,89,90,103 427/66
• US Class Current: 427/66
• CPC Class Codes: H10K 50/11 characterised by the electroluminescent [EL] layers
• CPC Class Codes: H10K 59/35 comprising red-green-blue [RGB] subpixels
• CPC Class Codes: Y10S 428/917 Electroluminescent

Abstract

A multi-color electroluminescent display has a plurality of discrete, laterally spaced areas of light emitting material formed over respective groups of first and second electrode regions. The light emissive material over each group is capable of emitting radiation of a different color. The multi-colored device is formed by a sequence of steps where each emitting layer is deposited as. a precursor which is susceptible to patterning and which is then converted into its polymer which is not susceptible to subsequent patterning steps. This allows a second color to be deposited on top of a first color, the second color being patterned while avoiding damage to the first color below it.

Claims

1. A method of fabricating a multi-colour electroluminescent display, comprising the steps of:

forming on a substrate a plurality of first electrode regions;

forming over a first selected group of said first electrode regions a first layer of a precursor for a first organic polymeric material for emitting radiation of a first colour, said precursor for said first material being susceptible to patterning,

at least partially converting said precursor for said first material into said first material, the product of the at least partially converted precursor being substantially resistant to subsequent patterning steps;

depositing over said first layer and over at least a second selected group of said first electrode regions a second layer of a precursor for a second organic polymeric material for emitting radiation of a second colour, said precursor for said second material being susceptible to patterning;

patterning said second layer to remove said second layer from above said first layer and leaving said second layer over said second selected group of said first electrode regions;

at least partially converting said precursor for said second material into said second material;

finally converting any partially-converted precursors into said respective materials;

forming a plurality of second electrode regions over said layers in such a manner that said materials for emitting radiation can be selectively excited to emit radiation by applying an electric field between said first and second electrode regions.

2. A method of fabricating a multi-colour electroluminescent display according to claim 1, wherein said step of forming a plurality of first electrode regions comprises the steps of:

depositing a layer of a conductive material on a substrate; and

patterning said layer of said conductive material to form a plurality of first electrode regions.

3. A method of fabricating a multi-colour electroluminescent display according to claim 2, wherein said step of forming a first layer of a precursor for a first material comprises the steps of:

depositing a layer of a precursor for a first material for emitting radiation of a first colour over said first electrode regions; and

patterning said layer of said precursor for said first material to form a layer of said precursor for said first material over a first selected group of said first electrode regions.

4. A method of fabricating a multi-colour electroluminescent display according to claim 2, wherein said step of forming a plurality of second electrode regions comprises the steps of:

depositing a layer of a conductive material over said layers; and

patterning said layer of conductive material to form a plurality of second electrode regions.

5. A method of fabricating a multi-colour electroluminescent display according to claim 1, wherein said step of forming a first layer of a precursor for a first material comprises the steps of:

depositing a layer of a precursor for a first material for emitting radiation of a first colour over said first electrode regions; and

patterning said layer of said precursor for said first material to form a layer of said precursor for said first material over a first selected group of said first electrode regions.

6. A method of fabricating a multi-colour electroluminescent display according to claims 1, wherein said step of forming a plurality of second electrode regions comprises the steps of:

depositing a layer of a conductive material over said layers; and

patterning said layer of conductive material to form a plurality of second electrode regions.

7. A method of fabricating a multi-colour electroluminescent display according to claim 1, wherein said steps of at least partially converting said precursor for said second material into said second material and finally converting any partially-converted precursors for said first and second materials into said first and second materials are performed in a single step.

8. A method of fabricating a multi-colour electroluminescent display according to claim 1, wherein the product of at least partially converting said precursor for said second material is substantially resistant to subsequent patterning steps, and further comprising, after said step of at least partially converting said precursor for said second material, the steps of:

depositing over said first and second layers and over a third selected group of said first electrode regions a third layer of a precursor for a third organic polymeric material for emitting radiation of a third colour, said precursor for said third material being susceptible to patterning;

patterning said third layer to remove said third layer from over said first and second layers and leaving said third layer over said third selected group of said first electrode regions; and

at least partially converting said precursor for said third material into said third material.

9. A method of fabricating a multi-colour electroluminescent display according to claim 8, wherein said steps of at least partially converting said precursor for said third material into said third material and finally converting any partially-converted precursors for said first, second and third materials into said first, second and third materials are performed in a single step.

10. A method of fabricating a multi-colour electroluminescent display according to claim 1, wherein said polymer materials are selected from poly(p-phenylene vinylene) for a green colour, poly(p-phenylene) or poly(p-phenylene vinylene) co-polymer with non-conjugated sections for a blue colour, poly(1,4-naphthylene vinylene) or a dialkoxy substituted polyp-phenylene vinylene) for a red colour;

the poly(p-phenylene) precursors comprising;

(a)(i) poly(5,6 dialkyloxy—

1,3 cyclohexadiene) with an optional monosubstitution or 2,5 disubstitution of alkoxy, alkyl, aryloxy, aryl, nitrile, nitro or —

CF₃

the poly(p-phenylene vinylene) precursor comprising;

(b)(i) poly(p-xylylene-α

-dialkyl sulphonium halide);

(b)(ii) poly(p-xylylene-α

-cycloalkyl sulphonium halide);

(b)(iii) poly(p-xylylene-α

-halide);

(b)(iv) poly(p-xylylene-α

-alkoxide) where the alkyl ether can contain a cross-linkable group;

(b)(v) poly(p-xylylene-α

-aryloxide) where the aromatic ester can be substituted by a cross-linkable group;

(b)(vi) poly(p-xylylene-α

-carboxylate) where the ester can be aliphatic or aromatic and contain a cross-linkable group;

(b)(vii) a polymer comprising recurring units of the general formula;

X denotes —

SR³, —

SO—

R³, —

SO₂—

R³, —

COOR³, —

NO₂, —

CN, —

CF₃ or —

R³,

R¹, R², R³ are the same or different and denote —

H, —

R⁴ or —

X,

R⁴ denotes a straight chain or branched alkyl group with 1 to 20 carbon atoms, phenyl or benzyl, either of which can be substituted once or twice with —

R³, —

OR¹, —

NO₂, —

CN, —

Br, —

Cl or —

F, and

Ar denotes a phenylene group which can optionally be substituted;

or

(b)(viii) one of (b)(i) to (b)(vii) with a monosubstitution or 2,5 disubstitution of alkoxy, alkyl, aryloxy, aryl, nitrile, nitro or —

CF₃

the poly(1,4-naphthylene vinylene) precursor comprising;

(c)(i) poly(1,4 benzoxylylene-α

-dialkyl sulphonium halide);

(c)(ii) poly(1,4 benzoxylylene-α

-cycloalkyl sulphonium halide);

(c)(iii) poly(1,4 benzoxylylene-α

-halide)

(c)(iv) poly(1,4 benzoxylylene-α

-alkoxide) where the alkyl ether can contain a cross-linkable group;

(c)(v) poly(1,4 benzoxylylene-α

-aryloxide) where the aromatic ester can be substituted by a cross-linkable group;

(c) (vi) poly(1,4 benzoxylylene-α

-carboxylate) where the ester can be aliphatic or aromatic and contain a cross-linkable group; and

(c) (vii) a polymer comprising recurring units of the general formula;

X denotes —

SR³, —

SO—

R³, —

SO₂—

R³, —

COOR³, —

NO₂, —

CN, —

CF₃ or —

R³,

R¹, R², R³ are the same or different and denote —

H, —

R⁴, or —

X,

R⁴ denotes a straight chain or branched alkyl group with 1 to 20 carbon atoms, phenyl or benzyl, either of which can be substituted once or twice with —

R³, —

OR¹, —

NO₂, —

CN, —

Br, —

Cl or —

F, and

Ar denotes a naphthalene group which can optionally be substituted.

11. A method of fabricating a multi-colour electroluminescent display according to claim 1, wherein said polymer materials are selected from the group consisting of thiophene, furan, pyrrole and pyridine polymers, the precursors comprising a thiophene, furan, pyrrole or pyridine analogue of

(i) poly(5,6-dialkyloxy-1,3-cyclohexadiene);

(ii) poly(p-xylylene-α

-dialkyl sulphonium halide);

(iii) poly(p-xylylene-α

-cycloalkyl sulphonium halide);

(iv) poly(p-xylylene-α

-halide);

(v) poly(p-xylylene-α

-alkoxide), where the alkylether can contain a cross-linkable group;

(vi) poly(p-xylylene-α

-aryloxide), where the aromatic ester can be substituted by a cross-linkable group;

(vii) poly(p-xylylene-α

-carboxylate), where the ester can be aliphatic or aromatic and contain a cross-linkable group;

or

(viii) one of (i) to (vii) with a monosubstitution or 2, 5 disubstitution of alkoxy, alkyl, aryloxy, aryl, nitrile, nitro or —

CF₃.

12. A method of fabricating a multi-colour electroluminescent display according to claim 1, wherein said polymer materials are selected from the group consisting of thiophene, furan, pyrrole and pyridine polymers, the precursor comprising a polymer comprising recurring units of the following general formula:

X denotes —

SR³, —

SO—

R³, —

SO₂—

R³, —

COOR³, —

NO₂, —

CN, —

CF₃ or —

R³,

R¹, R², R³ are the same or different and denote —

H, —

R⁴ or —

X,

R⁴ denotes a straight chain or branched alkyl group with 1 to 20 carbon atoms, phenyl or benzyl, either of which can be substituted once or twice with —

R³, —

OR¹, —

NO₂, —

CN, —

Br, —

Cl or —

F, and

Ar denotes a furan, thiophene, pyrrole or pyridine system which can optionally be substituted.