US-12622133-B2 - Display device and method for manufacturing thereof

US12622133B2US 12622133 B2US12622133 B2US 12622133B2US-12622133-B2

Abstract

To provide a display device, in which deterioration in characteristics is small even when some of layers are exposed to a solvent or an atmosphere when photolithography is performed, and a method for manufacturing the display device. The display device having a pixel including a plurality of sub-pixels includes: a substrate; a lower electrode provided on an upper side of the substrate; an organic EL layer provided on the lower electrode and including an emission layer configured to emit a different color for each sub-pixel; and an upper electrode disposed on an upper side of the organic EL layer. An exposure protection layer having transparency and conductivity provided for each sub-pixel is formed between the organic EL layer and the upper electrode. No emission layer is formed between the exposure protection layer and the upper electrode.

Inventors

Takahiro Ushikubo
Hayata AOKI
Jun Nitta
Hiroumi KINJO

Assignees

MAGNOLIA WHITE CORPORATION

Dates

Publication Date: 20260505
Application Date: 20230724
Priority Date: 20220729

Claims (4)

1 . A display device comprising: a substrate; and a plurality of pixels provided on the substrate, each of the plurality of pixels including a plurality of sub-pixels, wherein each of the plurality of pixels comprises: a lower electrode provided on an upper side of the substrate; an organic EL layer provided on the lower electrode and including an emission layer configured to emit a different color for each sub-pixel; and an upper electrode disposed on an upper side of the organic EL layer, the organic EL layer comprises a first hole injection layer disposed on the lower electrode, a first hole transport layer disposed on the first hole injection layer, a first electron blocking layer disposed on the first hole transport layer, a first emission layer disposed on the first electron blocking layer and configured to emit red, green, or blue light, a first hole blocking layer disposed on the first emission layer, a charge generation layer disposed on the first hole blocking layer, a second hole transport layer disposed on the charge generation layer, a second electron blocking layer disposed on the second hole transport layer, a second emission layer disposed on the second electron blocking layer and configured to emit red, green, or blue light, a second hole blocking layer disposed on the second emission layer, an electron transport layer disposed on the second hole blocking layer, and a second electron injection layer disposed on the electron transport layer, an exposure protection layer having transparency and conductivity provided for each sub-pixel is formed between the organic EL layer and the upper electrode, and no emission layer is formed between the exposure protection layer and the upper electrode.
2 . The display device according to claim 1 , wherein the organic EL layer has a tandem structure including at least two layers of the emission layer for each of the sub-pixels.
3 . The display device according to claim 1 , wherein the exposure protection layer contains the same material as the upper electrode.
4 . The display device according to claim 1 , further comprising: a bank disposed between the adjacent sub-pixels and configured to partition the adjacent sub-pixels.

Description

CROSS-REFERENCE TO RELATED APPLICATION The present application claims priority from Japanese application No. 2022-121820 filed on Jul. 29, 2022, the content of which is hereby incorporated by reference into this application. BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a display device and a method for manufacturing thereof. 2. Description of the Related Art In an organic electroluminescence (EL) display device, a thin film transistor (TFT), an organic light emitting diode (OLED), and the like are formed on a substrate. The OLED includes an organic layer between a pair of electrodes. The organic layer is formed by stacking, for example, a hole transport layer, an emission layer, and an electron transport layer. The emission layer may be formed of a material that emits white light, or may be formed of a material that emits a different color for each sub-pixel constituting a pixel. When the emission layer is formed of a material that emits white light, there is a risk that current leakage occurs between adjacent sub-pixels (see JP 2008-243559 A), and there is a problem that luminance is lowered due to absorption of light by a color filter. Therefore, in recent years, the emission layer is often formed of a material that emits a different color for each sub-pixel. In order to solve the above problem, JP 2008-243559 A discloses that a hole transport layer, which is formed on an upper portion of a partition wall and serves as a path through which a leakage current flows, is removed. When an emission layer emitting a different color for each sub-pixel is formed, a leakage current generated between adjacent sub-pixels and absorption of light by a color filter can be reduced. However, since it is necessary to form an organic EL layer by photolithography, some of layers are exposed to an atmosphere or a solvent, and characteristics may deteriorate. SUMMARY OF THE INVENTION The present disclosure has been made in view of the above problem, and an object of the present disclosure is to provide a display device, in which deterioration in characteristics is small even when some of layers are exposed to a solvent or an atmosphere when photolithography is performed, and a method for manufacturing the display device. In order to solve the above problem, a display device according to one aspect of the present disclosure is a display device having a pixel including a plurality of sub-pixels. The display device includes: a substrate; and a plurality of pixels provided on the substrate, each of the plurality of pixels including a plurality of sub-pixels. Each of the plurality of pixels includes: a lower electrode provided on an upper side of the substrate; an organic EL layer provided on the lower electrode and including an emission layer configured to emit a different color for each sub-pixel; and an upper electrode disposed on an upper side of the organic EL layer. An exposure protection layer having transparency and conductivity provided for each sub-pixel is formed between the organic EL layer and the upper electrode. No emission layer is formed between the exposure protection layer and the upper electrode. A method for manufacturing a display device according to another aspect of the present disclosure includes steps of: forming a lower electrode on an upper side of a substrate; forming an organic EL layer on the lower electrode, the organic EL layer including an emission layer configured to emit a different color for each sub-pixel; forming an exposure protection layer having transparency and conductivity for each sub-pixel in contact with the organic EL layer; and forming an upper electrode on an upper side of the exposure protection layer. No emission layer is formed between the exposure protection layer and the upper electrode. According to the invention, it is possible to provide a display device, in which deterioration in characteristics is small even when some of layers are exposed to a solvent or an atmosphere when photolithography is performed, and a method for manufacturing the display device. BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a schematic diagram showing a schematic configuration of an organic EL display device according to an embodiment. FIG. 2 is a schematic plan view showing an example of the organic EL display device according to the present embodiment. FIG. 3 is a diagram showing a cross section around a pixel. FIG. 4 is a diagram showing a layer configuration of an organic EL layer and an exposure protection layer according to a first embodiment. FIG. 5A to FIG. 5D are diagrams showing a method for manufacturing the organic EL display device. FIG. 6A to FIG. 6D are diagrams showing a method for manufacturing the organic EL display device. FIG. 7A to FIG. 7D are diagrams showing a method for manufacturing the organic EL display device. FIG. 8 is a diagram showing a layer configuration of an organic EL layer and an exposure protection layer according to a s