Electroluminescent display and process for producing the same

• US 20040021413A1
• Filed: 07/30/2003
• Published: 02/05/2004
• Est. Priority Date: 07/31/2002
• Status: Active Grant

• Current Assignee: Dai Nippon Printing Company Limited
• Original Assignee: Dai Nippon Printing Company Limited
• Inventors: Ito, Norihito, Ito, Nobuyuki
• Granted Patent: US 7,307,381 B2
• Time in Patent Office: Days
• US Class Current: 313/504
• CPC Class Codes: H10K 59/122 Pixel-defining structures or layers, e.g. banks
• CPC Class Codes: H10K 71/135 using ink-jet printing
• CPC Class Codes: H10K 85/1135 Polyethylene dioxythiophene [PEDOT]; Derivatives thereof
• CPC Class Codes: H10K 85/146 poly N-vinylcarbazol; Derivatives thereof
• CPC Class Codes: H10K 85/60 Organic compounds having low molecular weight H10K85/10 - H10K85/50 take precedence
• CPC Class Codes: H10K 85/615 Polycyclic condensed aromatic hydrocarbons, e.g. anthracene
• CPC Class Codes: Y10S 428/917 Electroluminescent
• CPC Class Codes: Y10T 428/24777 Edge feature

Abstract

There is provided an organic electroluminescent display having excellent practicality that can be produced by a simple method which does not cause electrode breaking and can realize even thickness of an electroluminescent layer. There is also provided a pattern formed object having a coating as an electroluminescent layer or the like having even thickness, for an electroluminescent element, formed using a coating liquid and provided in each area surrounded by partition walls provided on a substrate. The electroluminescent display comprises at least a substrate, an electrode provided on the substrate, protrusions which each are provided on the substrate so as to cover the ends of the electrode and are convexly curved in section relatively to the surface of the substrate, and an electroluminescent layer provided in each opening which is located on the electrode and defined by adjacent protrusions. The pattern formed object comprises: a substrate; partition walls provided on the substrate; and a coating stacked on the substrate in its part between the partition walls, wherein the partition walls have a sloped liquid-nonrepellent surface and have such a sectional form that, at least in the lower part of the partition wall, as the distance from the substrate increases, the size of the partition wall in a direction parallel to the substrate decreases, and, in the coating, the ratio of the maximum thickness (Tmax) to the minimum thickness (Tmin), Tmax/Tmin, is not more than 130% as measured in the coating in its part between the lower ends of the partition walls adjacent to each other.

Claims

1. An electroluminescent display comprising

a substrate,

an electrode provided on the substrate,

protrusions which each are provided on the

substrate so as to cover the ends of the electrode and are convexly curved in section relatively to the surface of the substrate, and

an electroluminescent layer provided in each opening which is located on the electrode and defined by adjacent protrusions.

2. The electroluminescent display according to claim 1, wherein the electroluminescent layer in its part around the boundary between the electroluminescent layer and the protrusion is in contact with the protrusion in such a state that the electroluminescent layer is curved in section in a direction opposite to the convexly curved protrusion.

3. The electroluminescent display according to claim 1, wherein the electroluminescent layer in its part around the boundary between the electroluminescent layer and the protrusion is in smooth and continuous contact with the protrusion.

4. The electroluminescent display according to claim 1, wherein the sectional form of the protrusion comprises a part of an arc.

5. The electroluminescent display according to claim 1, wherein the sectional form of the protrusion comprises a part of an arc and a flat part as an upper part which is extended continuously from the arc part.

6. The electroluminescent display according to claim 1, wherein the thickness of the protrusion is not less than 5 μ

m.

7. A process for producing an electroluminescent display, comprising the step of

forming an organic layer including at least an electroluminescent layer on the surface of the substrate with protrusions provided thereon as defined in any one of claims 1 to 6 by a wet process selected from an ink jet method, a printing method, a casting method, an alternating adsorption method, a spin coating method, a dipping method, and a dispenser method.

8. An electronic equipment comprising the display according to any one of claims 1 to 6 as a display part.

9. A pattern formed object comprising:

a substrate;

partition walls provided on the substrate; and

a coating formed on the substrate in its part between the partition walls, wherein

said partition walls have a liquid-nonrepellent surface and have such a sectional form that, at least in the lower part of the partition wall, as the distance from the substrate increases, the size of the partition wall in a direction parallel to the substrate decreases, and

in said coating, the ratio of the maximum thickness (Tmax) to the minimum thickness (Tmin), Tmax/Tmin, is not more than 130% as measured in the coating in its part between the lower ends of the partition walls adjacent to each other.

10. The pattern formed object according to claim 9, wherein the angle of the lower part of the partition wall to the substrate is not more than 60 degrees.

11. The pattern formed object according to claim 10, wherein each of the partition walls comprises a lower partition wall structure, which is provided on the substrate side and is in the form of a trapezoid, in section, with the long side being located on the substrate side, and an upper partition wall structure provided on the lower partition wall structure.

12. The pattern formed object according to claim 11, wherein the angle of the slope of the lower partition wall structure to the substrate is not more than 30 degrees.

13. The pattern formed object according to claim 11, wherein the distance between the lower part of the upper partition wall structure and the end of the lower partition wall structure on its substrate side as measured in a direction parallel to the substrate is not less than 1 μ

m.

14. The pattern formed object according to claim 11, wherein the height H₁ of the lower partition wall structure as measured in a direction perpendicular to the substrate and the height H₂ of the upper partition wall structure satisfy a requirement represented by H₂>

2×

H₁>

0.1 μ

m.

15. A pattern formed object for an electroluminescent element, comprising the pattern formed object according to any one of claims 9 to 14, said coating being an EL light emitting layer interposed between a first electrode and a second electrode.

16. The pattern formed object for an electroluminescent element according to claim 15, wherein said EL light emitting layer has a hole injection layer stacked on its substrate side.

17. A method for pattern formation, comprising the steps of:

forming, on a substrate, partition walls which have a liquid-nonrepellent surface and have such a sectional form that, at least in the lower part of the partition wall, as the distance from the substrate increases, the size of the partition wall in a direction parallel to the substrate decreases;

applying a coating liquid onto the substrate in its part between the partition walls adjacent to each other; and

drying and solidifying the coating to form a solidified coating of which the ratio of the maximum thickness (Tmax) to the minimum thickness (Tmin), Tmax/Tmin, is not more than 130% as measured in the coating in its part between the lower ends of the partition walls adjacent to each other.

18. The method for pattern formation according to claim 17, wherein said partition wall is formed by forming a lower partition wall structure, which is provided on the substrate side and is in the form of a trapezoid, in section, with the long side being located on the substrate side, and then forming an upper partition wall structure provided on the lower partition wall structure.

19. A method for pattern formation for an electroluminescent element, comprising the steps of:

forming a first electrode on a substrate;

forming partition walls according to the method as defined in claim 17;

forming a coating as an EL light emitting layer using a coating liquid for EL light emitting layer formation according to the method as defined in claim 17;

and

forming a second electrode on the EL light emitting layer.

20. The method for pattern formation for an electroluminescent element according to claim 19, wherein the coating liquid for EL light emitting layer formation is applied by a dispenser method or an ink jet method.

21. The method for pattern formation for an electroluminescent element according to claim 19 or 20, wherein, prior to the formation of the EL light emitting layer, a hole injection layer is formed in a space between the partition walls adjacent to each other.

22. The method for pattern formation for an electroluminescent element according to claim 19 or 20, wherein, prior to the formation of the EL light emitting layer, a hole injection layer is formed on the whole area of the assembly including the upper surface of the partition walls.