METHODS FOR MANUFACTURING ORGANIC EL DISPLAY PANEL AND ORGANIC EL DISPLAY DEVICE

• US 20120135556A1
• Filed: 02/03/2012
• Published: 05/31/2012
• Est. Priority Date: 07/15/2010
• Status: Active Grant

• Current Assignee: JDI Design and Development GK
• Original Assignee: Panasonic Corporation (Panasonic Holdings Corporation)
• Inventors: TAKEUCHI, Takayuki
• Granted Patent: US 8,524,328 B2
• Time in Patent Office: Days
• US Class Current: 438/34
• CPC Class Codes: H10K 59/121 characterised by the geometry or disposition of pixel elements
• CPC Class Codes: H10K 59/122 Pixel-defining structures or layers, e.g. banks
• CPC Class Codes: H10K 59/123 Connection of the pixel electrodes to the thin film transistors [TFT]
• CPC Class Codes: H10K 71/135 using ink-jet printing

Abstract

Provided is an organic EL display panel offering improved luminance without increasing the current density of current flowing through organic light-emitting layers, comprising: substrate; TFT layer formed on substrate; planarizing film formed above TFT layer and having contact holes; lower electrodes arranged above planarizing film in a matrix in one-to-one correspondence with pixel units, and brought into conduction with TFT layer via contact holes; grid-shaped bank formed above planarizing film and defining openings corresponding one-to-one to lower electrodes; organic light-emitting layers formed in openings; and upper electrode formed above light-emitting layers. Each contact hole is positioned between a pair of openings adjacent in the column direction. At least one of opposing sides of any pair of openings adjacent in the column direction is reduced in width in the row direction and extends in the column direction so as to be adjacent in the row direction to the corresponding contact hole.

Claims

1. A method of manufacturing an organic EL display panel, comprising the steps of:

preparing a substrate;

forming a TFT layer on the substrate;

forming a planarizing film above the TFT layer;

providing a plurality of contact holes in the planarizing film such that the contact holes penetrate the planarizing film;

arranging a plurality of lower electrodes in a matrix above the planarizing film in such a manner that the TFT layer and the lower electrodes are brought into conduction via the contact holes, the lower electrodes corresponding one-to-one to pixel units;

forming, above the planarizing film, a bank defining a plurality of openings corresponding one-to-one to the lower electrodes;

forming organic light-emitting layers in the openings in one-to-one correspondence; and

forming an upper electrode above the organic light-emitting layers, wherein the bank is formed such that

each contact hole is positioned between a corresponding pair of the openings adjacent in a column direction, and

at least one of opposing sides of any pair of the openings adjacent in the column direction includes a reduced-width area that (i) is reduced in width in a row direction and (ii) extends in the column direction so as to be adjacent in the row direction to a corresponding one of the contact holes,

the organic light-emitting layers are formed by (i) causing a plurality of nozzles provided in an inkjet head to eject drops of ink into each opening, the ink containing one or more solvents and one or more organic materials to constitute the organic light-emitting layers, and (ii) drying the one or more solvents by evaporation, and

in the step of forming the organic light-emitting layers,

the inkjet head is positioned so that the nozzles are aligned in the column direction,

while the inkjet head is being moved in the row direction, every one of the nozzles is set to eject the drops of ink by (i) causing predetermined nozzles that pass over the contact holes to eject the drops of ink into the reduced-width area of each opening, the predetermined nozzles being included among the nozzles, and (ii) causing the rest of the nozzles other than the predetermined nozzles to eject the drops of ink into an area of each opening excluding the reduced-width area thereof, and

as to any pair of the openings adjacent in the column direction, a column-direction gap between opposing edges of the reduced-width area of one opening and the other opening is smaller than a column-direction gap between any pair of the nozzles adjacent in the column direction.

2. The method according to claim 1, wherein

the bank is formed such that

said opposing side of the other opening includes a reduced-width area that is reduced in width in the row direction,

as to any pair of the openings adjacent in the column direction, the reduced-width area of one opening extends in the column direction past the corresponding contact hole so as to be partially adjacent in the row direction to the reduced-width area of the other opening, and

the direction in which each reduced-width area extends alternates in the column direction.

3. The method according to claim 1, wherein

in the step of forming the bank, a plurality of concavities are formed in portions of the bank as a result of the portions sinking into the contact holes, and

in the step of forming the organic light-emitting layers, the predetermined nozzles that pass over the contact holes are caused to further eject the drops of ink into each concavity.

4. The method according to claim 1 further comprising the step of forming charge transport layers in the openings in one-to-one correspondence, wherein

the step of forming the charge transport layers is performed between the step of forming the bank and the step of forming the organic light-emitting layers, and

the charge transport layers are formed by (i) causing the nozzles provided in the inkjet head to eject drops of another ink into each opening, said another ink containing one or more solvents and one or more organic materials to constitute the charge transport layers, and (ii) drying the one or more solvents by evaporation.

5. The method according to claim 4, wherein

in the step of forming the charge transport layers,

the inkjet head is positioned so that the nozzles are aligned in the column direction, and

while the inkjet head is being moved in the row direction, every one of the nozzles is set to eject the drops of said another ink by (i) causing the predetermined nozzles that pass over the contact holes to eject the drops of said another ink into the reduced-width area of each opening, and (ii) causing the rest of the nozzles to eject the drops of said another ink into the area of each opening excluding the reduced-width area thereof.

6. The method according to claim 5, wherein

in the step of forming the bank, a plurality of concavities are formed in portions of the bank as a result of the portions sinking into the contact holes, and

in the step of forming the charge transport layers, the predetermined nozzles that pass over the contact holes are caused to further eject the drops of said another ink into each concavity.