DISPLAY APPARATUS

A display apparatus includes: a first organic light-emitting diode, a second organic light-emitting diode, and a third organic light-emitting diode corresponding to a first sub-pixel, a second sub-pixel, and a third sub-pixel, respectively; a first intermediate layer commonly provided in the first organic light-emitting diode and the second organic light-emitting diode, and comprising a first emission layer and a first n-type charge generation layer; a second intermediate layer provided in the third organic light-emitting diode, and comprising a second emission layer and a second n-type charge generation layer, wherein the first n-type charge generation layer includes a first material, and the second n-type charge generation layer includes a second material different from the first material.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application claims priority from and the benefit of Korean Patent Application No. 10-2020-0154573, filed on Nov. 18, 2020, which is hereby incorporated by reference for all purposes as if fully set forth herein.

BACKGROUND

Field

Embodiments of the invention relate generally to display apparatuses.

Discussion of the Background

Display apparatuses visually display data. A display apparatus includes a substrate that is divided into a display area and a peripheral area in which an image is not capable of being displayed. In the display area, a scan line and a data line are insulated from each other, and a plurality of sub-pixels are included. In addition, a thin-film transistor and a sub-pixel electrode electrically connected to the thin-film transistor are provided in the display area to correspond to each of the sub-pixels. Furthermore, an opposite electrode commonly provided in the sub-pixels may be provided in the display area. The peripheral area may include various lines configured to transmit electrical signals to the display area, a scan driver, a data driver, a controller, a pad portion, and the like.

The usage of such display apparatuses has diversified. Accordingly, various designs have been attempted to improve the quality of display apparatuses.

SUMMARY

One or more embodiments include a display apparatus having a longer lifespan with reduced power consumption. However, these objectives are examples and do not limit the scope of the present disclosure.

According to an embodiment, a display apparatus including a first sub-pixel, a second sub-pixel, and a third sub-pixel emitting light of different colors includes a first organic light-emitting diode, a second organic light-emitting diode, and a third organic light-emitting diode arranged on a substrate and corresponding to the first sub-pixel, the second sub-pixel, and the third sub-pixel, respectively, a first intermediate layer commonly provided in the first organic light-emitting diode and the second organic light-emitting diode and including a first emission layer and a first charge generation layer, a second intermediate layer provided in the third organic light-emitting diode and including a second emission layer and a second charge generation layer, and a first color conversion layer, a second color conversion layer, and a transmission layer arranged to correspond to the first organic light-emitting diode, the second organic light-emitting diode, and the third organic light-emitting diode, respectively, wherein the first emission layer emits light of a different color from the second emission layer, the first charge generation layer includes a first material, and the second charge generation layer includes a second material different from the first material.

The first and charge generation layers may be n-type charge generation layers, and in the first n-type charge generation layer, a host may be doped with 0.5% to 20% of the first material, and in the second n-type charge generation layer, a host may be doped with 0.5% to 20% of the second material.

The second material may have a shallower work function than the first material.

Each of the first material and the second material may have a work function of 2.0 eV to 3.0 eV.

The first material may include at least one of ytterbium (Yb), calcium (Ca), terbium (Tb), and cerium (Ce), and the second material may include at least one of lithium (Li), potassium (K), rubidium (Rb), cesium (Cs), barium (Ba), europium (Eu), sodium (Na), strontium (Sr), and samarium (Sm).

The first emission layer may emit green light, and the second emission layer may emit blue light.

The display apparatus may further include a bank arranged on the substrate and arranged between the first emission layer and the second emission layer.

The bank may be arranged over an upper portion of a pixel-defining layer and may be arranged to surround the third organic light-emitting diode, wherein the upper portion of the pixel-defining layer defines an emission area of the first to third organic light-emitting diodes.

The second intermediate layer may further include a (2-1)st(second intermediate) emission layer above or below the second emission layer.

The first intermediate layer may include the (2-1)st(second intermediate) emission layer.

The (2-1)st(second intermediate) emission layer and the second emission layer may emit light of a same color.

The first intermediate layer may further include a (1-1)st(first intermediate) emission layer above or below the first emission layer, and the (1-1)st(first intermediate) emission layer and the first emission layer may emit light of a same color.

The display apparatus may further include a first color filter, a second color filter, and a third color filter corresponding to the first color conversion layer, the second color conversion layer, and the transmission layer, respectively.

A thickness of the transmission layer may be about 1 μm to about 12 μm, and a thickness of the third color filter may be about 0.5 μm to about 5 μm.

A thickness of the first color conversion layer and the second color conversion layer may be about 2 μm to about 18 μm.

The first color conversion layer may include first quantum dots, and a content of the first quantum dots in the first color conversion layer may be about 10% to about 60%.

The first color conversion layer may include scattering particles, and a content of the scattering particles in the first color conversion layer may be about 2% to about 10%.

The first organic light-emitting diode, the second organic light-emitting diode, and the third organic light-emitting diode may include a first sub-pixel electrode, a second sub-pixel electrode, and a third sub-pixel electrode, respectively.

The display apparatus may further include an opposite electrode commonly provided in the first organic light-emitting diode, the second organic light-emitting diode, and the third organic light-emitting diode.

According to another embodiment, a display apparatus including a first sub-pixel, a second sub-pixel, and a third sub-pixel emitting light of different colors includes a first organic light-emitting diode, a second organic light-emitting diode, and a third organic light-emitting diode arranged on a substrate and corresponding to the first sub-pixel, the second sub-pixel, and the third sub-pixel, respectively, a first intermediate layer commonly provided in the first organic light-emitting diode and the second organic light-emitting diode and including a first emission layer and a first n-type charge generation layer, a second intermediate layer provided in the third organic light-emitting diode, the second intermediate layer including a second emission layer emitting light of a different color from the first emission layer, and a second n-type charge generation layer, and a bank arranged to at least partially surround the second intermediate layer.

DETAILED DESCRIPTION

Display apparatuses display an image, and for example, may be organic light-emitting display apparatuses, inorganic light-emitting display apparatuses, quantum dot light-emitting display apparatuses, and the like.

In the following description, an organic light-emitting display apparatus is described as an example of a display apparatus according to an embodiment. However, a display apparatus of the present disclosure is not limited thereto, and display apparatuses of various types may be used.

FIGS. 1A and 1Bare plan views schematically illustrating a display apparatus according to one or more embodiments that has been constructed according to principles of the invention.

Referring toFIG. 1A, the display apparatus may be formed by bonding a substrate100and an upper substrate200to each other by a sealing member600. The sealing member600may be formed to surround an outer periphery surface of the substrate100and the upper substrate200to bond the substrate100and the upper substrate200together.

The display apparatus may include a display area DA and a peripheral area PA around the display area DA. The display apparatus may provide an image using light emitted from a plurality of sub-pixels arranged in the display area DA.

The display area DA may include sub-pixels P that are connected to a data line DL extending in an x direction and a scan line SL extending in a y direction orthogonal to or substantially orthogonal to the x direction. Each of the sub-pixels P may also be connected to a driving voltage line PL extending in the x direction.

Each of the sub-pixels P may include a display element such as an organic light-emitting diode (OLED). Each of the sub-pixels P may emit red, green, blue, or white light, for example, through the organic light-emitting diode (OLED). In some embodiments, independent of a color of light emitted from the organic light-emitting diode (OLED) included in the sub-pixels P, a color of each sub-pixel P may be implemented by a color filter or the like arranged above the organic light-emitting diode (OLED).

Each of the sub-pixels P may be electrically connected to internal circuits arranged in the peripheral area PA. A first power supply line10, a second power supply line20, and a pad portion30may be arranged in the peripheral area PA.

The first power supply line10may be arranged to correspond to one side of the display area DA. The first power supply line10may be connected to the driving voltage lines PL configured to transmit a driving voltage ELVDD (seeFIGS. 2A and 2B) to the sub-pixels P.

The second power supply line20may partially surround the display area DA in a loop shape with one side open. The second power supply line20may be configured to apply a common voltage to an opposite electrode of the sub-pixel P. The second power supply line20may also be referred to as a common voltage supply line.

The pad portion30includes pads31and may be arranged at one side of the substrate100. Each of the pads31may be connected to a first connection line41connected to the first power supply line10, a connection line CW extending to the display area DA, or the like. The pads31of the pad portion30are exposed without being covered with an insulating layer, and may be electrically connected to a printed circuit board PCB. A PCB terminal portion PCB—P of the printed circuit board PCB may be electrically connected to the pad portion30.

The printed circuit board PCB transmits a signal or power from a controller to the pad portion30. The controller may respectively provide the driving voltage ELVDD and a common voltage ELVSS (seeFIGS. 2A and 2B) to the first power supply line10and the second power supply line20, respectively through the first connection line41and a second connection line42.

A data driving circuit60is electrically connected to the data line DL. A data signal of the data driving circuit60may be provided to each of the sub-pixels P through the connection line CW connected to the pad portion30and the data line DL connected to the connection line CW. AlthoughFIG. 1Ashows that the data driving circuit60is arranged on the printed circuit board PCB, in an embodiment, the data driving circuit60may be arranged on the substrate100. For example, the data driving circuit60may be arranged between the pad portion30and the first power supply line10.

A dam portion120may be arranged in the peripheral area PA. When forming an organic encapsulation layer420(seeFIG. 4) of a thin-film encapsulation layer400(seeFIG. 4), the dam portion120may block an organic material from flowing in an edge direction of the substrate100and prevent an edge tail of the organic encapsulation layer420from being formed. In the peripheral area PA, the dam portion120may at least partially surround the display area DA. The dam portion120may include a plurality of dams, and in this case, the dams may be spaced apart from each other. In the peripheral area PA, the dam portion120may be closer to the display area DA than the sealing member600. The peripheral area PA may further include an internal driving circuit portion (not shown) that provides a scan signal to each sub-pixel P. In an embodiment, the internal driving circuit portion and the dam portion120may overlap each other.

FIG. 1Ashows that one printed circuit board PCB is attached to the pad portion30, but a plurality of printed circuit boards PCB may be attached to the pad portion30as shown inFIG. 1B.

In addition, the pad portion30may be arranged along two sides of the substrate100. The pad portion30may include a plurality of sub-pad portions30S, and one printed circuit board PCB may be attached for each of the sub-pad portions30S.

FIGS. 2A and 2Bare equivalent circuit diagrams of a sub-pixel of a display apparatus according to an embodiment.

Referring toFIG. 2A, each sub-pixel P (seeFIG. 1A) may be implemented by a pixel circuit PC connected to a scan line SL and a data line DL, and an organic light-emitting diode OLED connected to the pixel circuit PC. The pixel circuit PC may include a driving thin-film transistor T1, a switching thin-film transistor T2, and a storage capacitor Cst. The switching thin-film transistor T2is connected to the scan line SL and the data line DL and may transmit a data signal Dm received via the data line DL to the driving thin-film transistor T1according to a scan signal Sn received via the scan line SL.

The storage capacitor Cst is connected to the switching thin-film transistor T2and a driving voltage line PL and may be configured to store a voltage corresponding to a voltage difference between a voltage received via the switching thin-film transistor T2and the first power supply voltage ELVDD (or a driving voltage) applied to the driving voltage line PL.

The driving thin-film transistor T1is connected to the driving voltage line PL and the storage capacitor Cst and may control a driving current flowing from the driving voltage line PL to the organic light-emitting diode OLED corresponding to the voltage stored in the storage capacitor Cst. The organic light-emitting diode OLED may emit light having a luminance according to the driving current.

InFIG. 2A, the pixel circuit PC includes two thin-film transistors and one storage capacitor, but the present disclosure is not limited thereto.

Referring toFIG. 2B, a pixel circuit PC may include a driving thin-film transistor T1, a switching thin-film transistor T2, a sensing thin-film transistor T3, and a storage capacitor Cst.

A scan line SL may be connected to a gate electrode G2of the switching thin-film transistor T2, a data line DL may be connected to a source electrode S2of the switching thin-film transistor T2, and a first electrode CE1of the storage capacitor Cst may be connected to a drain electrode D2of the switching thin-film transistor T2.

Accordingly, the switching thin-film transistor T2may apply a data voltage of the data line DL to a first node N in response to a scan signal Sn received from the scan line SL of each sub-pixel P.

A gate electrode G1of the driving thin-film transistor T1may be connected to the first node N, a source electrode S1of the driving thin-film transistor T1may be connected to the driving voltage line PL for transmitting a driving voltage ELVDD, and a drain electrode D1of the driving thin-film transistor T1may be connected to an anode electrode of an organic light-emitting diode OLED.

Thus, the driving thin-film transistor T1may control a current flowing through the organic light-emitting diode OLED according to a source-gate voltage Vgs thereof, that is, a voltage applied between the driving voltage ELVDD and the first node N.

A sensing control line SSL may be connected to a gate electrode G3of the sensing thin-film transistor T3, a source electrode S3of the sensing thin-film transistor T3may be connected to a second node S, and a drain electrode D3of the sensing thin-film transistor T3may be connected to a reference voltage line RL. In an embodiment, the sensing thin-film transistor T3may be controlled by the scan line SL instead of the sensing control line SSL.

The sensing thin-film transistor T3may sense a potential of a sub-pixel electrode (e.g., an anode electrode) of the organic light-emitting diode OLED. The sensing thin-film transistor T3may apply a pre-charging voltage received via the reference voltage line RL to the second node S in response to a sensing signal SSn received via the sensing control line SSL, or may apply a voltage of the sub-pixel electrode (for example, the anode electrode) of the organic light-emitting diode OLED to the reference voltage line RL during a sensing period.

The first electrode CE1of the storage capacitor Cst may be connected to the first node N, and a second electrode CE2of the storage capacitor Cst may be connected to the second node S. The storage capacitor Cst may charge a voltage difference between voltages respectively applied to the first node N and the second node S, and supply the charged voltage as a driving voltage of the driving thin-film transistor T1. For example, the storage capacitor Cst may charge a voltage difference between a data voltage Dm and a pre-charging voltage Vpre respectively applied to the first node N and the second node S.

A bias electrode BSM may be formed to correspond to the driving thin-film transistor T1, and connected to the source electrode S3of the sensing thin-film transistor T3. The bias electrode BSM receives a voltage in connection with a potential of the source electrode S3of the sensing thin-film transistor T3, and thus, the driving thin-film transistor T1may be stabilized. In an embodiment, the bias electrode BSM may not be connected to the source electrode S3of the sensing thin-film transistor T3, but may be connected to a separate bias line.

An opposite electrode (for example, a cathode electrode) of the organic light-emitting diode OLED may receive a common voltage ELVSS. The organic light-emitting diode OLED may receive a driving current from the driving thin-film transistor T1to emit light.

InFIG. 2B, each of the sub-pixels P (seeFIG. 1A) includes the scan line SL, the sensing control line SSL, the data line DL, the reference voltage line RL, and a driving voltage line PL, the present disclosure is not limited thereto. For example, at least one of the scan line SL, the sensing control line SSL, the data line DL, and/or the reference voltage line RL, and the driving voltage line PL may be shared with neighboring sub-pixels.

The pixel circuit PC is not limited to the number of thin-film transistors and storage capacitors and the circuit design described with reference toFIGS. 2A and 2B, and various modifications to the number and circuit design thereof is possible.

FIG. 3is a plan view schematically illustrating part of a display apparatus according to an embodiment.

InFIG. 3, a first sub-pixel P1, a second sub-pixel P2, and a third sub-pixel P3are sequentially arranged in an x direction in a stripe arrangement, but the present disclosure is not limited thereto. The first sub-pixel P1, the second sub-pixel P2, and the third sub-pixel P3may be arranged in various ways, for example, in a pentile matrix arrangement, a mosaic arrangement, a delta arrangement, and the like.

In an embodiment, a first emission layer EMLa may be arranged in the first sub-pixel P1area and the second sub-pixel P2area, and a second emission layer EMLb may be arranged in the third sub-pixel P3area. In other words, an emission layer arranged in an area in which the first sub-pixel P1and the second sub-pixel P2are arranged may differ from an emission layer arranged in an area in which the third sub-pixel P3is arranged. The emission layer will be described later below.

A bank119bmay be arranged to separate the area where the first sub-pixel P1and the second sub-pixel P2are arranged from the area where the third sub-pixel P3is arranged. The bank119bmay be arranged between the first sub-pixel P1and the third sub-pixel P3and between the second sub-pixel P2and the third sub-pixel P3. In an embodiment, the bank119bmay surround at least a portion of the third sub-pixel P3. The bank119bis not arranged between the first sub-pixel P1and the second sub-pixel P2, but may surround at least a portion of the first sub-pixel P1and the second sub-pixel P2.

FIG. 4is a cross-sectional view schematically illustrating part of a display apparatus according to one or more embodiments.FIG. 4may correspond to line I-I′ inFIG. 3.

Referring toFIG. 4, at least one thin-film transistor T1and a display element connected to the at least one thin-film transistor T1may be arranged in a display area DA of the display apparatus according to an embodiment. In the display area ofFIG. 4, the driving thin-film transistor T1and the storage capacitor Cst of the pixel circuit PC described with reference toFIGS. 2A and 2Bare shown.

The display area DA of the display apparatus includes first, second, and third sub-pixels P1, P2, and P3, each of which may include an emission area EA. The emission area EA may be an area where light is generated and emitted to the outside. A non-emission area NEA may be arranged between each emission area EA, and the emission areas EA of the first, second, and third sub-pixels P1, P2, and P3may be distinguished by the non-emission area NEA.

In an embodiment, the display apparatus may include a color conversion layer corresponding to at least one sub-pixel. For example, as shown inFIG. 4, a first color conversion layer QD1and a second color conversion layer QD2may be arranged to correspond to the first sub-pixel P1and the second sub-pixel P2, respectively. Each of the first and second color conversion layers QD1and QD2may include quantum dots and scattering particles.

Also, no color conversion layer corresponds to the emission area EA of the third sub-pixel P3, but a transmission layer TW may be arranged in the emission area EA of the third sub-pixel P3. The transmission layer TW may include an organic material capable of emitting light without converting a wavelength of light emitted from a third organic light-emitting diode OLED3of the third sub-pixel P3.

In an embodiment, a first organic light-emitting diode OLED1and a second organic light-emitting diode OLED2respectively included in the first sub-pixel P1and the second sub-pixel P2may emit light of a same color. The third organic light-emitting diode OLED3included in the third sub-pixel P3may emit light of a color different from the color of light emitted from the first organic light-emitting diode OLED1included in the first sub-pixel P1and the second organic light-emitting diode OLED2included in the second sub-pixel P2.

Hereinafter, for convenience of explanation, the elements arranged in the display area DA ofFIG. 4will be described according to a stacked order.

The substrate100may include a glass material, a ceramic material, a metal material, or a material that is flexible or bendable. When the substrate100is flexible or bendable, the substrate100may include a polymer resin such as polyether sulfone, polyacrylate, polyether imide, polyethylene naphthalate, polyethylene terephthalide, polyphenylene sulfide, polyarylate, polyimide, polycarbonate, or cellulose acetate propionate. The substrate100may have a single layer or a multi-layer structure of the above material, and for a multi-layer structure, may further include an inorganic layer. In some embodiments, the substrate100may have a structure of an organic material, an inorganic material, and another organic material.

A first buffer layer111may be arranged on the substrate100. The first buffer layer111may be located on the substrate100and reduce or block the penetration of foreign materials, moisture, or ambient air into a lower portion of the substrate100, and may provide a flat surface on the substrate100. In an embodiment, the first buffer layer111may include an inorganic insulating material such as silicon oxide (SiO2), silicon nitride (SiNX), silicon oxynitride (SiOXNY), aluminum oxide (Al2O3), titanium oxide (TiO2), tantalum oxide (Ta2O5), hafnium oxide (HfO2), or zinc oxide (ZnO). For example, the first buffer layer111may include silicon oxide (SiO2) or silicon nitride (SiNX).

A barrier layer (not shown) may be further included between the substrate100and the first buffer layer111. The barrier layer may prevent or reduce impurities from the substrate100and the like from penetrating into a semiconductor layer A1. The barrier layer may include an inorganic material such as an oxide or a nitride, or may include an organic material, or may include an organic/inorganic composite material, and may have a single layer or a multi-layer structure of an inorganic material and an organic material.

A bias electrode BSM may be arranged on the first buffer layer111to correspond to the driving thin-film transistor T1. A voltage may be applied to the bias electrode BSM. For example, the bias electrode BSM may be connected to the source electrode S3(seeFIG. 2B) of the sensing thin-film transistor T3(seeFIG. 2B) to receive voltage of the source electrode S3. In addition, the bias electrode BSM may prevent external light from reaching the semiconductor layer A1. Thus, the characteristics of the driving thin-film transistor T1may be stabilized. In some cases, the bias electrode BSM may be omitted.

A second buffer layer112may be arranged on the bias electrode BSM. The second buffer layer112and the first buffer layer111may include a same material. In some embodiments, the second buffer layer112and the first buffer layer111may include different materials from each other.

The semiconductor layer A1may be arranged on the second buffer layer112. The semiconductor layer A1may include amorphous silicon or polysilicon. In an embodiment, the semiconductor layer A1may include an oxide of at least one material selected from the group consisting of indium (In), gallium (Ga), stannum (Sn), zirconium (Zr), vanadium (V), hafnium (Hf), cadmium (Cd), germanium (Ge), chromium (Cr), titanium (Ti), aluminum (Al), cesium (Cs), cerium (Ce), and zinc (Zn). In an embodiment, the semiconductor layer A1may include a Zn oxide-based material, such as a Zn oxide, an In—Zn oxide, and a Ga—In—Zn oxide. In another embodiment, the semiconductor layer A1may include In—Ga—Zn—O (IGZO), In—Sn—Zn—O (ITZO), or In—Ga—Sn—Zn—O (IGTZO) semiconductor, in which a metal such as indium (In), gallium (Ga), or stannum (Sn) is included in zinc oxide (ZnO). The semiconductor layer A1may include a channel area, a source area, and a drain area, wherein the source area and the drain area are arranged at opposite sides of the channel area, respectively. The semiconductor layer A1may include a single layer or multiple layers.

A gate insulating layer113may be arranged on the semiconductor layer A1. The gate insulating layer113may include an inorganic insulating material such as silicon oxide (SiO2), silicon nitride (SiNX), silicon oxynitride (SiOXNY), aluminum oxide (A12O3), titanium oxide (TiO2), tantalum oxide (Ta2O5), hafnium oxide (HfO2), or zinc oxide (ZnO).

A gate electrode G1may be arranged on the semiconductor layer A1with the gate insulating layer113therebetween, so as to at least partially overlap the semiconductor layer A1. The gate electrode G1may include molybdenum (Mo), aluminum (Al), copper (Cu), titanium (Ti), etc., and may include a single layer or multiple layers. In an embodiment, the gate electrode G1may include a single Mo layer. A first electrode CE1of a storage capacitor Cst and the gate electrode G1may be arranged on a same layer. The first electrode CE1and the gate electrode G1may include a same material. In an embodiment, the first electrode CE1and the gate electrode G1may be provided as a single body.

An interlayer insulating layer115may be arranged on the gate electrode G1and the first electrode CE1. The interlayer insulating layer115may include an inorganic insulating material such as silicon oxide (SiO2), silicon nitride (SiNX), silicon oxynitride (SiOXNY), aluminum oxide (Al2O3), titanium oxide (TiO2), tantalum oxide (Ta2O5), hafnium oxide (HfO2), or zinc oxide (ZnO).

The source electrode S1, the drain electrode D1, a data line DL (not shown), and a second electrode CE2of the storage capacitor Cst may be arranged on the interlayer insulating layer115.

Each of the source electrode S1, the drain electrode D1, the data line, and the second electrode CE2of the storage capacitor Cst may include a conductive material including molybdenum (Mo), aluminum (A1), copper (Cu), titanium (Ti), etc., and may include a single layer or multiple layers including the above material. In an embodiment, each of the source electrode S1, the drain electrode D1, the data line DL, and the second electrode CE2may have a multi-layer structure of a Ti layer, an A1layer, and another Ti layer. The source electrode S1and the drain electrode D1may be respectively connected to the source area and the drain area of the semiconductor layer A1through a contact hole.

The second electrode CE2of the storage capacitor Cst may overlap the first electrode CE1with the interlayer insulating layer115therebetween. Thus, the first electrode CE1and the second electrode CE2may form a capacitance. In this case, the interlayer insulating layer115may function as a dielectric layer of the storage capacitor Cst.

The source electrode S1, the drain electrode D1, the data line, and the second electrode CE2of the storage capacitor Cst may be covered with an inorganic protective layer PVX.

The inorganic protective layer PVX may be a single film or multiple films including silicon oxide (SiO2), silicon nitride (SiNX), silicon oxynitride (SiOXNY), aluminum oxide (Al2O3), titanium oxide (TiO2), tantalum oxide (Ta2O5), hafnium oxide (HfO2), or zinc oxide (ZnO). The inorganic protective layer PVX may be introduced to cover and protect some lines arranged on the interlayer insulating layer115. Lines (not shown) formed together in a same process as the data line may be exposed in a portion of the substrate100(e.g., a portion of a peripheral area). An exposed portion of the lines may be damaged by an etchant used to pattern a sub-pixel electrode310to be described below, but because the inorganic protective layer PVX may cover the data line and at least a portion of the lines formed together with the data line DL, the lines may be prevented from being damaged in the patterning process of the sub-pixel electrode310.

A planarization layer118may be arranged on the inorganic protective layer PVX, and a first organic light-emitting diode OLED1, a second organic light-emitting diode OLED2, and the third organic light-emitting diode OLED3may be arranged on the planarization layer118.

The planarization layer118may be formed as a single layer or multiple layers including an organic material and may provide a flat upper surface. The planarization layer118may include a general-purpose polymer (for example, benzocyclobutene, polyimide, hexamethyldisiloxane, polymethylmethacrylate, or polystyrene), a polymer derivative having a phenol-based group, an acryl-based polymer, an imide-based polymer, an aryl-ether-based polymer, an amide-based polymer, a fluorine-based polymer, a p-xylene-based polymer, a vinyl-alcohol-based polymer, and any blends thereof.

In the display area DA of the substrate100, the first organic light-emitting diode OLED1, the second organic light-emitting diode OLED2, and the third organic light-emitting diode OLED3may be arranged on the planarization layer118. The first organic light-emitting diode OLED1may be arranged in the first sub-pixel P1area, the second organic light-emitting diode OLED2may be arranged in the second sub-pixel P2area, and the third organic light-emitting diode OLED3may be arranged in the third sub-pixel P3area. Each of the first organic light-emitting diode OLED1, the second organic light-emitting diode OLED2, and the third organic light-emitting diode OLED3may include a sub-pixel electrode310, an intermediate layer including an emission layer, and an opposite electrode330.

The sub-pixel electrode310may be arranged on the planarization layer118. In an embodiment, the sub-pixel electrode310may be patterned and formed to correspond to each of the first, second, and third organic light-emitting diodes OLED1, OLED2, and OLED3. The sub-pixel electrode310may be electrically connected to a pixel circuit PC (seeFIG. 2B).

The pixel electrode310may be a (semi-)light-transmitting electrode or a reflective electrode. In some embodiments, the sub-pixel electrode310may include a reflective layer including silver (Ag), magnesium (Mg), aluminum (A1), platinum (Pt), palladium (Pd), gold (Au), nickel (Ni), neodymium (Nd), iridium (Ir), chromium (Cr), or any compounds thereof, and a transparent or translucent electrode layer formed on the reflective layer. The transparent or translucent electrode layer may include at least one material selected from the group consisting of indium tin oxide (ITO), indium zinc oxide (IZO), zinc oxide (ZnO), indium oxide (In2O3), indium gallium oxide (IGO), and aluminum zinc oxide (AZO). In an embodiment, the sub-pixel electrode310may be provided as an ITO layer, an Ag layer, and another ITO layer.

A pixel-defining layer119amay be arranged on the planarization layer118, and the pixel-defining layer may have an opening corresponding to each of the sub-pixels in the display area DA, that is, an opening OP exposing at least a portion of the sub-pixel electrode310, thereby defining the emission areas EA of the first, second, and third sub-pixels P1, P2, and P3. For example, the pixel-defining layer119amay have the opening OP through which at least a portion of a central portion of the sub-pixel electrode310is exposed. In addition, the pixel-defining layer119amay prevent an arc, etc. from occurring at an edge of the sub-pixel electrode310by increasing a distance between the edge of the sub-pixel electrode310and the opposite electrode330above the sub-pixel electrode310.

The pixel-defining layer119amay include at least one organic insulating material selected from the group consisting of polyimide, polyamide, an acryl-based resin, benzocyclobutene, and a phenol resin, and may be formed by spin coating, etc.

Each of the first organic light-emitting diode OLED1and the second organic light-emitting diode OLED2includes a first intermediate layer320a, and the first intermediate layer320amay include a first emission layer EMLa. The third organic light-emitting diode OLED3includes a second intermediate layer320b, and the second intermediate layer320bmay include a second emission layer EMLb. In the first organic light-emitting diode OLED1, the second organic light-emitting diode OLED2, and the third organic light-emitting diode OLED3, a functional layer such as a hole injection layer (HIL), a hole transport layer (HTL), an electron transport layer (ETL), an electron injection layer (EIL), and the like may be selectively further arranged below and above the first and second emission layers EMLa and EMLb.

In an embodiment, the first organic light-emitting diode OLED1and the second organic light-emitting diode OLED2may commonly include the first emission layer EMLa, and the third organic light-emitting diode OLED3may include the second emission layer EMLb.

The first emission layer EMLa and the second emission layer EMLb may emit light of different colors from each other. In an embodiment, the first emission layer EMLa may include an organic material emitting green light, and the second emission layer EMLb may include an organic material emitting blue light. The first emission layer EMLa may be formed by using, for example, a green dopant in a host material. For example, the first emission layer EMLa may include a phosphorescent host material such as Tris(4-carbazoyl-9-ylphenyl)amine (TCTA), 4,4′-Bis(N-carbazolyl)-1,1′-biphenyl (CBP), Bis(8-hydroxy-2-methylquinoline)-(4-phenylphenoxy)aluminum (BAlq), Poly(p phenylene vinylene) (PPV), and the like. In addition, the first emission layer EMLa may be doped with a phosphorescent dopant such as Ir(ppy)3or Ir(mmapy)3.

The second emission layer EMLb may be formed by using, for example, a blue dopant in a host material. For example, the second emission layer EMLb includes a host material including CBP or mCP, and may include a phosphorescent material including a dopant material including (4,6-F2ppy)2Irpic. In contrast, the second emission layer EMLb may include a fluorescent material including any one selected from the group consisting of spiro-DPVBi, spiro-6P, distill benzene (D SB), distrylarylene (DSA), a PFO-based polymer, and a PPV-based polymer, but is not limited thereto.

In an embodiment, a color of light ultimately emitted by the first sub-pixel P1, the second sub-pixel P2, and the third sub-pixel P3is a color seen from the outside of an upper substrate200, and thus, when a same emission layer is applied to the first organic light-emitting diode OLED1, the second organic light-emitting diode OLED2, and the third organic light-emitting diode OLED3, a voltage applied to the first organic light-emitting diode OLED1, the second organic light-emitting diode OLED2, and the third organic light-emitting diode OLED3may vary depending on light emission efficiencies of the first color conversion layer QD1and the second color conversion layer QD2.

For example, when a blue emission layer is applied to all of the first organic light-emitting diode OLED1, the second organic light-emitting diode OLED2, and the third organic light-emitting diode OLED3, light conversion may be performed on the first sub-pixel P1and the second sub-pixel P emitting red light or green light so as to produce a same luminance as the third sub-pixel P3emitting blue light, thus increasing a driving voltage applied to the first organic light-emitting diode OLED1and the second organic light-emitting diode OLED2. Therefore, the power consumption may rapidly increase while the lifespan of the first and second organic light-emitting diode OLED1and OLED2may be reduced.

In an embodiment, considering this light conversion efficiency, the first emission layer EMLa may be employed for the first organic light-emitting diode OLED1and the second organic light-emitting diode OLED2, and the second emission layer EMLb emitting light of a different color from the first emission layer EMLa may be employed, to thereby reduce power consumption and enhance efficiency. In an embodiment, the first emission layer EMLa may emit green light, and the second emission layer EMLb may emit blue light.

The opposite electrode330may be a cathode that is an electron injection electrode, and in this case, a metal, an alloy, an electrically conductive compound, or any combinations thereof having a low work function may be used as a material for the opposite electrode330. The opposite electrode330may be a transmissive electrode, a semi-transmissive electrode, or a reflective electrode. The opposite electrode330may include lithium (Li), silver (Ag), magnesium (Mg), aluminum (Al), aluminum-lithium (Al—Li), calcium (Ca), magnesium-indium (Mg—In), magnesium-silver (Mg—Ag), ytterbium (Yb), silver-ytterbium (Ag—Yb), ITO, IZO, or any combinations thereof. The opposite electrode330may have a single layer structure that is a single layer, or a multi-layer structure having a plurality of layers.

The opposite electrode330may be arranged over the display area DA and the peripheral area PA (seeFIG. 1A) and may be arranged above the intermediate layer and the pixel-defining layer119a. The opposite electrode330may be formed as a single body with the first, second, and third organic light-emitting diodes OLED1, OLED2, and OLED3so as to overlap the plurality of sub-pixel electrodes310.

A bank119bmay be arranged on the pixel-defining layer119a. The bank119bmay be formed as a single body with pixel-defining layer119a. For example, the bank119band the pixel-defining layer119amay be formed simultaneously in a same process using a half tone mask process. In an embodiment, the bank119bmay include a liquid repellent material.

The bank119bmay be a structure for separating the first emission layers EMLa and the second emission layer EMLb from each other. The bank119bmay be arranged between the first organic light-emitting diode OLED1and the third organic light-emitting diode OLED3and between the second organic light-emitting diode OLED2and the third organic light-emitting diode OLED3. Because the first organic light-emitting diode OLED1and the second organic light-emitting diode OLED2have the first emission layer EMLa in common, the bank119bmay not be arranged between the first organic light-emitting diode OLED1and the second organic light-emitting diode OLED2.

The first organic light-emitting diode OLED1, the second organic light-emitting diode OLED2, and the third organic light-emitting diode OLED3may be covered with a thin-film encapsulation layer400because they may be easily damaged by moisture or oxygen from the outside. The thin-film encapsulation layer400may cover the display area DA and extend out of the display area DA. The thin-film encapsulation layer400may include at least one organic layer and at least one inorganic layer. For example, the thin-film encapsulation layer400may include a first inorganic layer410, an organic layer420, and a second inorganic layer430.

For example, the first inorganic layer410may cover the opposite electrode330and may include silicon oxide (SiO2), silicon nitride (SiNX), silicon oxynitride (SiOXNY), aluminum oxide (Al2O3), titanium oxide (TiO2), tantalum oxide (Ta2O5), hafnium oxide (HfO2), or zinc oxide (ZnO). Although not shown, other layers such as a capping layer and the like may be located between the first inorganic layer410and the opposite electrode330when necessary. Because the first inorganic layer410is formed along an underlying structure thereof, an upper surface of the first inorganic layer410may not be flat. The organic layer420may cover the first inorganic layer410and may have a substantially flat upper surface unlike the first inorganic layer410. For example, the organic layer420may have a substantially flat upper surface in a portion thereof corresponding to the display area DA. The organic layer420may include one or more materials selected from the group consisting of polyethylene terephthalate, polyethylene naphthalate, polycarbonate, polyimide, polyethylene sulfonate, polyoxymethylene, polyarylate, and hexamethyldisiloxane. The second inorganic layer430covers the organic layer420, and the second inorganic layer430and the organic layer420may include a same material or different materials from each other.

Through the aforementioned multi-layer structure, even when cracks occur in the thin-film encapsulation layer400, those cracks may be prevented from connecting between the first inorganic layer410and the organic layer420or between the organic layer420and the second inorganic layer430. Therefore, the formation of a passage through which external moisture or oxygen penetrate into the display area DA may be prevented or reduced.

A filler610may be arranged above the thin-film encapsulation layer400. The filler610may buffer an external pressure, etc. The filler610may include an organic material such as methyl silicone, phenyl silicone, polyimide, and the like. However, the present disclosure is not limited thereto, and the filler610may include a urethane-based resin, an epoxy-based resin, and an acryl-based resin that are organic sealants, or may include silicone, etc. that is an inorganic sealant.

The first and second color conversion layers QD1and QD2, the transmission layer TW, and a partition wall210may be arranged on an upper substrate200facing the substrate100. The partition wall210may further include scattering particles (not shown).

Each of the first and second color conversion layers QD1and QD2may include quantum dots. As described herein, quantum dots denotes a crystal of a semiconductor compound, and may include any material capable of emitting light of various emission wavelengths according to the crystal size

Quantum dots exhibit intrinsic excitation and emission characteristics according to materials and sizes, and thus, incident light may be converted into light of a color. Various materials may be employed for quantum dots. For example, the quantum dots may include Group II-VI compounds, Group III-V compounds, Group III-VI compounds, Group semiconductor compounds, Group IV-VI semiconductor compounds, Group IV elements or compounds, or any combinations thereof.

The Group III-V compounds may be selected from the group consisting of: a binary compound selected from the group consisting of GaN, GaP, GaAs, GaSb, AlN, AlP, AlAs, AlSb, InN, InP, InAs, InSb, and any blends thereof; a ternary compound selected from the group consisting of GaNP, GaNAs, GaNSb, GaPAs, GaPSb, AlNP, AlNAs, AlNSb, AlPAs, AlPSb, InGaP, InNP, InNAs, InNSb, InPAs, InPSb, GaAlNP, and any blends thereof; and a quaternary compound selected from the group consisting of GaAlNAs, GaAlNSb, GaAlPAs, GaAlPSb, GaInNP, GaInNAs, GaInNSb, GaInPAs, GaInPSb, InAlNP, InAlNAs, InAlNSb, InAlPAs, InAlPSb, and any blends thereof. Meanwhile, the Group III-V semiconductor compounds may further include a Group II element. For example, the Group III-V semiconductor compounds further including a Group II element may include InZnP, InGaZnP, InAlZnP, etc.

For example, the Group III-VI semiconductor compounds may include: a binary compound such as GaS, GaSe, Ga2Se3, GaTe, InS, InSe, In2S3, In2Se3, InTe, and the like; and a ternary compound such as InGaS3, InGaSe3, and the like; or any combinations thereof.

For example, the Group semiconductor compounds may include: ternary compounds such as AgInS, AgInS2, CuInS, CuInS2, CuGaO2, AgGaO2, AgAlO2, or the like; or any combinations thereof.

The Group IV-VI compounds may be selected from the group consisting of: a binary compound selected from the group consisting of SnS, SnSe, SnTe, PbS, PbSe, PbTe, and any blends thereof; a ternary compound selected from the group consisting of SnSeS, SnSeTe, SnSTe, PbSeS, PbSeTe, PbSTe, SnPbS, SnPbSe, SnPbTe, and any blends thereof; and a quaternary compound selected from the group consisting of SnPbSSe, SnPbSeTe, SnPbSTe, and any blends thereof.

The Group IV elements may be selected from the group consisting of Si, Ge, and any blends thereof. The Group IV elements may include a binary compound selected from the group consisting of SiC, SiGe, and any blends thereof.

At this time, the binary compounds, the ternary compounds, or the quaternary compounds may be present in particles at a uniform concentration, or may be present in a same particle in partially different concentration distributions.

Quantum dots may be formed in a core-shell structure having a core and a shell. An interface between the core and the shell may have a concentration gradient in which a concentration of elements in the shell decreases toward the center of the core.

The shell of the quantum dot may serve as a protective layer for maintaining semiconductor properties by preventing chemical denaturation of the core and/or a charging layer that imparts electrophoretic properties to the quantum dots. The shell may include a single layer or a multi-layer.

The quantum dot may have a size of about 45 nm or less, for example, about 40 nm or less, and for example, about 30 nm or less, and the color purity or color reproducibility may be improved in those ranges. In addition, because light emitted from the quantum dots is emitted in all directions, an optical viewing angle may be improved.

In addition, shapes of the quantum dot are not particularly limited to shapes commonly used in the art, but more specifically, spherical, pyramidal, multi-arm, or cubic nanoparticles, nanotubes, nanowires, nanofibers, nanoplatelets, and the like may be used.

The core of the quantum dot may have a diameter of about 2 to about 10 nm, and when the quantum dot is exposed to light, light of a frequency may be emitted depending on a particle size and a material type, and thus, an average size of quantum dots included in the first color conversion layer QD1and an average size of quantum dots included in the second color conversion layer QD2may be different from each other. For example, light of a color of a longer wavelength may be emitted as a size of the quantum dot increases. Thus, a size of the quantum dot may be selected according to a color of the first sub-pixel P1and the second sub-pixel P2.

In addition to the quantum dots, the first and second color conversion layers QD1and QD2may further include various materials for mixing and dispersing the quantum dots properly. For example, scattering particles, a solvent, a photoinitiator, a binder polymer, a dispersant, etc., may be further included.

No color conversion layer may be arranged in the emission area EA of the third sub-pixel P3, and the transmission layer TW may be arranged in the emission area EA of the third sub-pixel P3. The transmission layer TW may include an organic material capable of emitting light without converting a wavelength of light emitted from the third organic light-emitting diode OLED3. The transmission layer TW may include scattering particles for uniform color spreading. In this case, the scattering particles may have a diameter in a range of about 200 nm to about 400 nm.

In an embodiment, the transmission layer TW may have a thickness of about 1 μm to about 12 μm. When the thickness of the transmission layer TW is less than about 1 μm, the thickness of the transmission layer TW is so thin that the color spreadability is deteriorated, and therefore, the color purity or the color reproducibility may be deteriorated. On the other hand, when the thickness of the transmission layer TW exceeds about 12 μm, the thickness of the transmission layer TW is so thick that the light emission efficiency may be deteriorated. Therefore, when the thickness of the transmission layer TW is about 1 μm to about 12 μm, the color spreadability may be improved, and the color purity or the color reproducibility may also be improved.

In an embodiment, the first color conversion layer QD1may have a thickness of about 2 μm to about 18 μm. When the thickness of the first color conversion layer QD1is less than 2 μm, unconverted light may exist. On the other hand, when the thickness of the first color conversion layer QD1exceeds about 18 μm, the light conversion efficiency may be deteriorated. Therefore, when the thickness of the first color conversion layer QD1is about 2 μm to about 18 μm, the light conversion efficiency may be improved, and the color purity or color reproducibility of the sub-pixels may also be improved.

In an embodiment, the second color conversion layer QD2may have a thickness of about 2 μm to about 18 μm. When the thickness of the second color conversion layer QD2is less than about 2 μm, light that has not been converted may exist. On the other hand, when the thickness of the second color conversion layer QD2exceeds about 18 μm, the light conversion efficiency may be deteriorated. Accordingly, when the thickness of the second color conversion layer QD2is about 2 μm to about 18 μm, the light conversion efficiency may be improved, and the color purity or color reproducibility of the sub-pixels may be improved.

In an embodiment, the first color conversion layer QD1may include first quantum dots. A content of the first quantum dots in the first color conversion layer QD1may be about 10% to about 60%. When the content of the first quantum dots in the first color conversion layer QD1is less than about 10%, light that has not been converted by the first color conversion layer QD1may be present, and thus, the color purity or color reproducibility of the sub-pixels may be deteriorated. On the other hand, when the content of the first quantum dots in the first color conversion layer QD1exceeds about 60%, the quantum dots are close to each other, and thus, may collide with each other. Therefore, when about 10% to about 60% of the first quantum dots are included in the first color conversion layer QD1, the color purity or color reproducibility of the sub-pixels may be improved.

In an embodiment, the first color conversion layer QD1may include scattering particles. A content of the scattering particles in the first color conversion layer QD1may be about 2% to about 10%. When the content of the scattering particles in the first color conversion layer QD1is less than about 2%, light emitted from the organic light-emitting diode may not be scattered. On the other hand, when the content of the scattering particles in the first color conversion layer QD1exceeds about 10%, the scattered light may be directed to a place other than the color filter, thus deteriorating the light conversion efficiency and/or the light emission efficiency.

In an embodiment, the second color conversion layer QD2may include second quantum dots. A content of the second quantum dots in the second color conversion layer QD2may be about 10% to about 60%. When the content of the second quantum dots in the second color conversion layer QD2is less than about 10%, light that has not been converted by the second color conversion layer QD2may be present, and thus, the color purity or color reproducibility of the sub-pixels may be deteriorated. On the other hand, when the content of the second quantum dots in the second color conversion layer QD2exceeds about 60%, the quantum dots are close to each other and may collide with each other. Therefore, when the second quantum dots are included in about 10% to 60% in the second color conversion layer QD2, the color purity or color reproducibility of the sub-pixels may be improved.

In an embodiment, the second color conversion layer QD2may include scattering particles. A content of the scattering particles in the second color conversion layer QD2may be about 2% to about 10%. When the content of the scattering particles in the second color conversion layer QD2is less than about 2%, light emitted from the organic light-emitting diode may not be scattered. On the other hand, when the content of the scattering particles in the second color conversion layer QD2exceeds about 10%, the scattered light may be directed to a place other than the color filter, and thus, the light conversion efficiency and/or the light emission efficiency may be lowered.

In an embodiment, at least one of the first color conversion layer QD1and the second color conversion layer QD2may not include quantum dots, but may include scattering particles. For example, when the first sub-pixel P1emits red light, the second sub-pixel P2emits green light, and the third sub-pixel P3emits blue light, the transmission layer TW is applied instead of the second color conversion layer QD2, and thus, a color of the second sub-pixel P2may be implemented as a color of light emitted by the second organic light-emitting diode OLED2.

The partition wall210may be arranged between the first color conversion layer QD1, the second color conversion layer QD2, and the transmission layer TW to correspond to the non-emission area NEA. For example, the partition wall210may be arranged between the first color conversion layer QD1and the second color conversion layer QD2and between the second color conversion layer QD2and the transmission layer TW, etc.

The partition wall210may include an organic material and a material for controlling an optical density such as Cr or CrOX, Cr/CrOX, Cr/CrOX/CrNY, a resin (carbon pigment, RGB mixed pigment, etc.), a graphite, and a non-Cr-based material. In some embodiments, the partition wall210may include a pigment of colors such as red, green, and yellow. The partition wall210may serve as a black matrix to prevent color mixing and improve visibility.

A first color filter CF1, a second color filter CF2, a third color filter CF3, and a light-blocking pattern BM may be provided between the upper substrate200and each of the first and second color conversion layers QD1and QD2and the transmission layer TW.

The first, second, and third color filters CF1, CF2, and CF3may be introduced to implement full color images and improve color purity and outdoor visibility. The first color filter CF1may pass light converted in the first color conversion layer QD1and absorb light that is not converted. Likewise, the second color filter CF2may pass light converted in the second color conversion layer QD2and absorb light that is not converted. In an embodiment, the second color filter CF2may be implemented with a same color as light emitted from the second organic light-emitting diode OLED2. The third color filter CF3may be implemented with a same color as light emitted from the third organic light-emitting diode OLED3. In addition, the first, second, and third color filters CF1, CF2, and CF3may block light incident from the outside and suppress the emission of quantum dots of the first and second color conversion layers QD1and QD2.

In an embodiment, the third color filter CF3may have a thickness of about 0.5 μm to about 5 μm. When the thickness of the third color filter CF3is less than about 0.5 μm, light incident from the outside may not be blocked. On the other hand, when the thickness of the third color filter CF3exceeds about 5 μm, light is absorbed by the third color filter CF3, and the light emission efficiency may be deteriorated.

In an embodiment, the first color filter CF1may be provided in red, the second color filter CF2may be provided in green, and the third color filter CF3may be provided in blue.

A light-blocking pattern BM may be arranged between the first to third color filters CF1, CF2, and CF3so as to correspond to the non-emission area NEA. The light blocking pattern BM is a black matrix and may improve the color clarity and the contrast. The light-blocking pattern BM may include at least one of black pigment, black dye, and black particles. In some embodiments, the light-blocking pattern BM may include a material such as Cr, CrOX, Cr/CrOX, Cr/CrOX/CrNY, a resin (e.g., carbon pigment or RGB mixed pigment), a graphite, non-Cr-based material, and the like.

Color filters adjacent to each other among the first, second, and third color filters CF1, CF2, and CF3may overlap each other in the non-emission area NEA. Because color filters of different colors overlap each other, the light-blocking rate may increase. In some cases, the first, second, and third color filters CF1, CF2, and CF3and the light-blocking pattern BM may be omitted.

FIG. 5is a cross-sectional view schematically illustrating part of a display apparatus according to an embodiment.

Referring toFIG. 5, sub-pixel electrodes310of a first organic light-emitting diode OLED1, a second organic light-emitting diode OLED2, and a third organic light-emitting diode OLED3may be patterned to respectively correspond to the first organic light-emitting diode OLED1, the second organic light-emitting diode OLED2, and the third organic light-emitting diode OLED3.

The first organic light-emitting diode OLED1and the second organic light-emitting diode OLED2may include a first intermediate layer320a, and the first intermediate layer320amay include a first emission layer EMLa. In addition, the first intermediate layer320amay further include a hole injection layer HIL, a first hole transport layer HTLa, a first electron transport layer ETLa, and an electron injection layer EIL. The hole injection layer HIL may be arranged between the sub-pixel electrodes310and the first hole transport layer HTLa. The first hole transport layer HTLa may be arranged between the hole injection layer HIL and the first emission layer EMLa. The first electron transport layer ETLa may be arranged on the first emission layer EMLa so as to transport electrons coming from the opposite electrode330to the first emission layer EMLa. The electron injection layer EIL may be arranged between the first electron transport layer ETLa and the opposite electrode330.

The third organic light-emitting diode OLED3may include a second intermediate layer320b, and the second intermediate layer320bmay include a second emission layer EMLb. In addition, the second intermediate layer320bmay further include the hole injection layer HIL, a second hole transport layer HTLb, a second electron transport layer ETLb, and the electron injection layer EIL. The hole injection layer HIL may be arranged between the sub-pixel electrode310and the second hole transport layer HTLb. The second hole transport layer HTLb may be arranged between the hole injection layer HIL and the second emission layer EMLb. The second electron transport layer ETLb may be arranged above the second emission layer EMLb so as to transport electrons coming from an opposite electrode330to the second emission layer EMLb. The electron injection layer EIL may be arranged between the second electron transport layer ETLb and the opposite electrode330.

The hole injection layer HIL may be commonly applied to the first to third organic light-emitting diodes OLED1, OLED2, and OLED3. The hole injection layer HIL may enable a smooth hole injection, and may include one or more materials selected from the group consisting of HATCN, copper phthalocyanine (CuPc), poly(3,4)-ethylenedioxythiophene (PEDOT), polyaniline (PANT), and N, N-dinaphthyl-N, N′-diphenylbenzidine (NPD), but is not limited thereto.

In an embodiment, the first organic light-emitting diode OLED1and the second organic light-emitting diode OLED2may commonly include the first emission layer EMLa and the first hole transport layer HTLa, and the second emission layer EMLb and the second hole transport layer HTLb may be provided in the third organic light-emitting diode OLED3.

The first emission layer EMLa and the second emission layer EMLb may emit light of different colors from each other. In an embodiment, the first emission layer EMLa may include an organic material emitting green light, and the second emission layer EMLb may include an organic material emitting blue light.

The first emission layer EMLa may be formed by using, for example, a green dopant in a host material. The second emission layer EMLb may be formed by using, for example, a blue dopant in a host material.

The first hole transport layer HTLa may be arranged between the sub-pixel electrodes310of the first organic light-emitting diode OLED1and the second organic light-emitting diode OLED2and the first emission layer EMLa, and the second hole transport layer HTLb may be arranged between the sub-pixel electrode310of the third organic light-emitting diode OLED3and the second emission layer EMLb.

In an embodiment, a hole mobility of the first hole transport layer HTLa may be equal to a hole mobility of the second hole transport layer HTLb. In an embodiment, the hole mobility of the first hole transport layer HTLa may be different from the hole mobility of the second hole transport layer HTLb. For example, the hole mobility of the first hole transport layer HTLa may be less than that of the second hole transport layer HTLb.

In an embodiment, each of the first hole transport layer HTLa, and the second hole transport layer HTLb may include, as a host thereof, a triphenylamine derivative having high hole mobility and excellent stability, such as N, N′-diphenyl-N,N′-bis(3-methylphenyl)-1, 1′-bi-phenyl-4,4′-diamine (TPD), N,N′-di(naphthalen-1-yl)-N,N′-diphenyl-benzidine (NPB), and the like.

To control the hole mobilities of the first hole transport layer HTLa and the second hole transport layer HTLb, the host of the first hole transport layer HTLa may be doped with a P-type organic dopant so as to increase the hole mobility thereof. The P-type organic dopant may include a quinone derivative such as tetracyanoquinonedimethane (TCNQ) and 2,3,5,6-tetrafluoro-tetracyano-1,4-benzoquinonedimethane (F4-TCNQ), and a cyano-group-containing compound such as 2-(7-dicyanomethylene-1,3,4,5,6,8,9,10-octafluoro-7H-pyrene-2-ylidene)-malononitrile (NDP-9; a commercial product by Novaled Corporation). A doping concentration of the P-type organic dopant may be about 0.5% to about 25%.

The host of the second hole transport layer HTLb may be doped with an oxide having a high dielectric constant to reduce the hole mobility of the second hole transport layer HTLb. The dielectric constant of the oxide may have a value in a range of about 3 to about 60. The oxide may include one from among HfOX, ZrOX, LaOX, La2O3, LaAlOX, TaOX, AlOX, Al2O3, SiO2, ZrSiO4, HfSiO4, SrO, Y2O3, CaO, BaO, BaZrO, MgO, and TiO2. In this case, the doping concentration of the oxide may be about 0.5% to about 30%.

In an embodiment, the hole mobility may be controlled by doping the host with an oxide having a high dielectric constant with respect to both of the first hole transport layer HTLa and the second hole transport layer HTLb. For example, by lowering a doping concentration of the oxide doped on the first hole transport layer HTLa compared to a doping concentration of the oxide doped on the second hole transport layer HTLb, the hole mobility of the first hole transport layer HTLa may be controlled higher than the hole mobility of the second hole transport layer HTLb.

The first electron transport layer ETLa and the second electron transport layer ETLb may make the transport of electrons smooth, and may include one or more materials selected from the group consisting of tris(8-hydroxyquinolino)aluminum) (Alq3), PBD, TAZ, spiro-PBD, BAlq, lithium quinolate (Liq), BMB-3T, PF-6P, TPBI, COT, and SAlq, but are not limited thereto. In an embodiment, the first electron transport layer ETLa may include a different material from a material of the second electron transport layer ETLb. In an embodiment, the first electron transport layer ETLa and the second electron transport layer ETLb may include a same material.

The electron injection layer EIL may be commonly applied to the first to third organic light-emitting diodes OLED1, OLED2, and OLED3. For example, the electron injection layer EIL may be Yb, tris(8-hydroxyquinolino)aluminum (Alq3), PBD, TAZ, Spiro-PBD, BAlq or SAlq, but is not limited thereto.

FIG. 6is a cross-sectional view schematically illustrating part of a display apparatus according to an embodiment. InFIG. 6, the same reference symbols as those ofFIG. 5denote the same, and redundant descriptions thereof will be omitted for ease in explanation of the embodiment.

Referring toFIG. 6, the first and second intermediate layers320aand320bof the first to third organic light-emitting diodes OLED1, OLED2, and OLED3may be provided by stacking a plurality of emission layers. For example, the first intermediate layer320aof the first organic light-emitting diode OLED1and the second organic light-emitting diode OLED2may include the first emission layer EMLa and a (1-1)st(or, first intermediate) emission layer EMLa-1. In an embodiment, the (1-1)st emission layer EMLa-1and the first emission layer EMLa may include a same material. For example, each of the first emission layer EMLa and the (1-1)stemission layer EMLa-1may include an organic material that emits green light.

The second intermediate layer320bof the third organic light-emitting diode OLED3may include the second emission layer EMLb and a (2-1)st(or, second intermediate) emission layer EMLb-1. In an embodiment, the (2-1)stemission layer EMLb-1and the second emission layer EMLb may include a same material. For example, each of the second emission layer EMLb and the (2-1)stemission layer EMLb-1may include an organic material emitting blue light.

In an embodiment, the first intermediate layer320amay include a first stack321aincluding the first emission layer EMLa, a (1-1)ststack323aincluding the (1-1)stemission layer EMLa-1, and a first charge generation layer322atherebetween.

The first stack321amay be provided in a structure in which the hole injection layer HIL, the first hole transport layer HTLa, the first emission layer EMLa, and the first electron transport layer ETLa are sequentially stacked. The (1-1)ststack323amay have a structure in which a (1-1)st hole transport layer HTLa-1, the (1-1)stemission layer EMLa-1, and a (1-1)stelectron transport layer ETLa-1are sequentially stacked.

The first charge generation layer322amay supply electric charges to the first stack321aand the (1-1)ststack323a. The first charge generation layer322amay include an n-type charge generation layer and a p-type charge generation layer. In this case, the n-type charge generation layer and the p-type charge generation layer may be in direct contact with each other and form a PN junction. By the PN junction, electrons and holes may be simultaneously generated between the n-type charge generation layer and the p-type charge generation layer. The n-type denotes an n-type semiconductor property, that is, a property of injecting or transporting electrons. The p-type denotes a p-type semiconductor property, that is, a property of injecting or transporting holes.

The first charge generation layer322amay include a first n-type charge generation layer n-CGLa and a p-type charge generation layer p-CGL, wherein the first n-type charge generation layer is for supplying electrons to the first stack321a, and the p-type charge generation layer p-CGL is for supplying holes to the (1-1)ststack323a. The first n-type charge generation layer n-CGLa may include a metal material as a dopant.

Similarly, the second intermediate layer320bmay include a second stack321bincluding the second emission layer EMLb, a (2-1)ststack323bincluding the (2-1)stemission layer EMLb-1, and a second charge generation layer322btherebetween.

The second stack321bmay have a structure in which the hole injection layer HIL, the second hole transport layer HTLb, the second emission layer EMLb, and the second electron transport layer ETLb are sequentially stacked. The (2-1)ststack323bmay have a structure in which a (2-1)sthole transport layer HTLb-1, the (2-1)stemission layer EMLb-1, and a (2-1)stelectron transport layer ETLb-1are sequentially stacked.

The second charge generation layer322bmay supply charges to the second stack321band the (2-1)ststack323b. The second charge generation layer322bmay include a second n-type charge generation layer n-CGLb and a p-type electron generation layer p-CGL, wherein the second n-type charge generation layer is for supplying electrons to the second stack321b, and the p-type charge generation layer p-CGL is for supplying holes to the (2-1)ststack323b. The second n-type charge generation layer n-CGLb may include a metal material as a dopant.

Some elements of the first intermediate layer320aand the second intermediate layer320bmay include a same material. For example, the hole injection layer HIL and the electron injection layer EIL may be commonly applied to the first intermediate layer320aand the second intermediate layer320b.

For example, when a blue emission layer is applied to all of the first organic light-emitting diode OLED1, the second organic light-emitting diode OLED2, and the third organic light-emitting diode OLED3, light conversion may be performed on the first sub-pixel P1and the second sub-pixel P emitting red light or green light so as to produce a same luminance as the third sub-pixel P3emitting blue light, thus increasing a driving voltage applied to the first organic light-emitting diode OLED1and the second organic light-emitting diode OLED2. Therefore, the power consumption may rapidly increase while the lifespan of the first and second organic light-emitting diode OLED1and OLED2may be reduced.

To this end, a green emission layer may be applied to the first organic light-emitting diode OLED1and the second organic light-emitting diode OLED2, and a blue emission layer may be applied to the third organic light-emitting diode OLED3. However, when the blue emission layer is applied only to the third organic light-emitting diode OLED3, the efficiency and lifespan of the third organic light-emitting diode OLED3to which the blue emission layer is applied may be lower than the efficiency and lifespan of the first organic light-emitting diode OLED1and the second organic light-emitting diode OLED2to which the green emission layer is applied.

In an embodiment, the charge generation characteristic of the second n-type charge generation layer n-CGLb arranged in the third sub-pixel P3area may be improved compared to the charge generation characteristic of the first n-type charge generation layer n-CGLa arranged in the first sub-pixel P1area and the second sub-pixel P2area. For example, the charge generation characteristic of the second n-type charge generation layer n-CGLb arranged in the third sub-pixel P3may be improved compared to the charge generation characteristic of the first n-type charge generation layer n-CGLa arranged in the first sub-pixel P1area and the second sub-pixel P2area by controlling a material forming the first n-type charge generation layer n-CGLa and the second n-type charge generation layer n-CGLb and/or a content of the material.

In an embodiment, the first n-type charge generation layer n-CGLa and the second n-type charge generation layer n-CGLb may be provided by doping a host with a dopant. For example, the host of the first n-type charge generation layer n-CGLa and the second n-type charge generation layer n-CGLb may include a phosphine-oxide-based material, a phenanthroline-based material, etc., but is not limited thereto. A metal in the first n-type charge generation layer n-CGLa and the second n-type charge generation layer n-CGLb may be an alkali metal, an alkaline earth metal, a rare earth metal, a transition metal and a post-transition metal, or any combinations thereof. The metal may include lithium (Li), potassium (K), rubidium (Rb), cesium (Cs), barium (Ba), europium (Eu), sodium (Na), strontium (Sr), samarium (Sm), calcium (Ca), terbium (Tb), cerium (Ce), magnesium (Mg), scandium (Sc), yttrium (Y), ytterbium (Yb), gadolinium (Gd), or any combinations thereof.

In an embodiment, the first n-type charge generation layer n-CGLa may include a first material, and the second n-type charge generation layer n-CGLb may include a second material different from the first material.

In an embodiment, the first n-type charge generation layer n-CGLa may be provided by doping the host with a concentration of about 0.5% to about 20% of the first material. When a doping concentration of the first material in the first n-type charge generation layer n-CGLa is less than about 0.5%, an electrical conductivity of the first n-type charge generation layer n-CGLa is so low that the efficiency of the organic light-emitting diode may decrease. On the other hand, when a doping concentration of the first material in the first n-type charge generation layer n-CGLa exceeds about 20%, an electrical conductivity may rapidly increase, the first n-type charge generation layer n-CGLa may have the properties of a metal layer, and the first n-type charge generation layer n-CGLa may become opaque. Therefore, when the doping concentration of the first material in the first n-type charge generation layer n-CGLa is about 0.5% to about 20%, the efficiency of the organic light-emitting diode may be improved, and the first n-type charge generation layer n-CGLa may be provided in a transparent state. In an embodiment, the doping concentration of the first material in the first n-type charge generation layer n-CGLa may be about 1% to about 10%. In an embodiment, the doping concentration of the first material in the first n-type charge generation layer n-CGLa may be about 5%.

In an embodiment, the second n-type charge generation layer n-CGLb may be provided by doping the host with a concentration about 0.5% to about 20% of the second material. When a doping concentration of the second material in the second n-type charge generation layer n-CGLb is less than about 0.5%, an electrical conductivity of the second n-type charge generation layer n-CGLb is so low that the efficiency of the organic light-emitting diode may be deteriorated. On the other hand, when the doping concentration of the second material in the second n-type charge generation layer n-CGLb exceeds about 20%, an electrical conductivity may rapidly increase, the second n-type charge generation layer n-CGLb may have the properties of a metal layer, and the second n-type charge generation layer n-CGLb may become opaque. Therefore, when the doping concentration of the second material in the second n-type charge generation layer n-CGLb is about 0.5% to about 20%, the efficiency of the organic light-emitting diode may be improved, and the second n-type charge generation layer n-CGLb may be provided in a transparent state. In an embodiment, the doping concentration of the second material in the second n-type charge generation layer n-CGLb may be about 1% to about 10%. In an embodiment, the doping concentration of the second material in the second n-type charge generation layer n-CGLb may be about 5%.

In an embodiment, each of the first material and the second material may include lithium (Li), potassium (K), rubidium (Rb), cesium (Cs), barium (Ba), europium (Eu), sodium (Na), strontium (Sr), samarium (Sm), calcium (Ca), terbium (Tb), cerium (Ce), ytterbium (Yb), or any combinations thereof. At this time, a work function of lithium (Li) may be 2.30 eV, a work function of potassium (K) may be 2.29 eV, a work function of rubidium (Rb) may be 2.26 eV, a work function of cesium (Cs) may be 2.14 eV, a work function of barium (Ba) may be 2.52 eV, a work function of europium (Eu) may be 2.50 eV, a work function of sodium (Na) may be 2.36 eV, a work function of strontium (Sr) may be 2.59 eV, a work function of samarium (Sm) may be 2.69 eV, a work function of calcium (Ca) may be 2.87 eV, a work function of terbium (Tb) may be 3.00 eV, a work function of cerium (Ce) may be 2.90 eV, and a work function of ytterbium (Yb) may be 2.70 eV.

In an embodiment, the second material may have a shallower work function than the first material. In an embodiment, a work function of the first material and the second material may be about 2.0 eV to about 3.0 eV, and the work function of the second material may be less than the work function of the first material. For example, the first material may include at least one of ytterbium (Yb), calcium (Ca), terbium (Tb), and cerium (Ce), and the second material may include lithium (Li), potassium (K), rubidium (Rb), cesium (Cs), barium (Ba), europium (Eu), sodium (Na), strontium (Sr), samarium (Sm), or any combinations thereof having a shallower work function than the above-mentioned ytterbium (Yb), calcium (Ca), terbium (Tb), and cerium (Ce).

Table 1 is a table showing the measurement result of a driving voltage of an organic light-emitting diode including an n-type charge generation layer doped with lithium (Li) or ytterbium (Yb).

Referring to Table 1, it may be seen that, when a doping concentration of lithium (Li) in the n-type charge generation layer n-CGLa increases, the driving voltage drops. In addition, it may be seen that, at a same doping concentration (e.g., 5%), the driving voltage of the organic light-emitting diode including the n-type charge generation layer n-CGLa doped with ytterbium (Yb) is about 0.7 V greater than the driving voltage of the organic light-emitting diode including the n-type charge generation layer n-CGLa doped with lithium (Li). Because the driving voltage of the organic light-emitting diode including the n-type charge generation layer n-CGLa doped with lithium (Li) is less than the driving voltage of the organic light-emitting diode including the n-type charge generation layer n-CGLa doped with ytterbium (Yb), it may be seen that the efficiency of the organic light-emitting diode including the n-type charge generation layer n-CGLa doped with lithium (Li) is greater than the efficiency of the organic light-emitting diode including the n-type charge generation layer n-CGLa doped with ytterbium (Yb).

When the work function of the second material is shallower than the work function of the first material, the injection barrier with the electron transport layer ETL is lowered, and thus, the characteristics of the organic light-emitting diode may be improved.

Therefore, by doping the second n-type charge generation layer n-CGLb with a metal having a shallower work function than the first n-type charge generation layer n-CGLa, the injection barrier of the second n-type charge generation layer n-CGLb and the electron transport layer ETL is lowered, and thus, the characteristics of the organic light-emitting diode including the second n-type charge generation layer n-CGLb may be improved. Through this, the efficiency of the third organic light-emitting diode OLED3corresponding to the third sub-pixel P3may be improved, and the lifespan of the third organic light-emitting diode OLED3may also be improved.

FIG. 7is a cross-sectional view schematically illustrating part of a display apparatus according to an embodiment. InFIG. 7, the same reference symbols as those ofFIG. 6denote the same, and redundant descriptions thereof will be omitted for ease in explanation of the embodiment.

Referring toFIG. 7, the first intermediate layer320aand one of stacks of the second intermediate layer320bmay include a same material. For example, the (2-1)ststack323bof the second intermediate layer320bmay be commonly applied to the first intermediate layer320aand the second intermediate layer320b. Accordingly, the first intermediate layer320aof the first organic light-emitting diode OLED1and the second organic light-emitting diode OLED2may include the first emission layer EMLa and the (2-1)stemission layer EMLb-1, and the second intermediate layer320bof the third organic light-emitting diode OLED3may include the second emission layer EMLb and the (2-1)stemission layer EMLb-1. In an embodiment, the first emission layer EMLa may include an organic material emitting green light, and each of the second emission layer EMLb and the (2-1)stemission layer EMLb-1may include an organic material emitting blue light.

In an embodiment, when the first intermediate layer320aand one of stacks of the second intermediate layer320binclude a same material, a process may be simplified.

FIG. 7shows that the (2-1)ststack323bof the second intermediate layer320bis commonly applied to the first intermediate layer320aand the second intermediate layer320b, but the present disclosure is not limited thereto. Although not shown, the second stack321bof the second intermediate layer320bmay be commonly applied to the first intermediate layer320aand the second intermediate layer320b.

FIGS. 8 and 9are cross-sectional views schematically illustrating part of a display apparatus according to an embodiment. InFIGS. 8 and 9, the same reference symbols as those ofFIGS. 6 and 7denote the same, and redundant descriptions thereof will be omitted for ease in explanation of the embodiment.

Referring toFIGS. 8 and 9, the first and second intermediate layers320aand320bof the first to third organic light-emitting diodes OLED1, OLED2, and OLED3may be provided by stacking a plurality of emission layers.FIGS. 8 and 9show a structure in which three emission layers are stacked on one organic light-emitting diode, but the present disclosure is not limited thereto. Although not shown, four or more emission layers may be provided on one organic light-emitting diode.

In an embodiment, for example, the first intermediate layer320aof the first organic light-emitting diode OLED1and the second organic light-emitting diode OLED2may include the first emission layer EMLa, the (1-1)stemission layer EMLa-1, and a (1-2)ndemission layer EMLa-2. In an embodiment, the first emission layer EMLa, the (1-1)stemission layer EMLa-1, and the (1-2)ndemission layer EMLa-2may include a material emitting a same color as each other. For example, each of the first emission layer EMLa, the (1-1)st emission layer EMLa-1, and the (1-2)nd emission layer EMLa-2may include an organic material emitting green light.

In an embodiment, at least one of the first emission layer EMLa, the (1-1)stemission layer EMLa-1, and the (1-2)ndemission layer EMLa-2may include a material emitting light of a different color from the other ones. For example, each of the first emission layer EMLa, the (1-1)stemission layer EMLa-1, and the (1-2)ndemission layer EMLa-2may include an organic material that sequentially emits green light, green light, and blue light, or may include an organic material that sequentially emits green light, blue light, and green light, or may include an organic material that sequentially emits blue light, green light, and green light.

The second intermediate layer320bof the third organic light-emitting diode OLED3may include the second emission layer EMLb, the (2-1)stemission layer EMLb-1, and a (2-2)ndemission layer EMLb-2. In an embodiment, each of the second emission layer EMLb, the (2-1)stemission layer EMLb-1, and the (2-2)ndemission layer EMLb-2may include a material emitting light of a same color. For example, all of the second emission layer EMLb, the (2-1)stemission layer EMLb-1, and the (2-2)ndemission layer EMLb-2may include an organic material emitting blue light.

In an embodiment, the first intermediate layer320amay include the first stack321aincluding the first emission layer EMLa, the (1-1)ststack323aincluding the (1-1)stemission layer EMLa-1, a (1-2)ndstack325aincluding the (1-2)ndemission layer EMLa-2, and first and second charge generation layers322aand324a, wherein the first charge generation layer322ais between the first stack321aand the (1-1)ststack323a, and the second charge generation layer324ais between the (1-1)ststack323aand the (1-2)ndstack325a. The (1-2)ndstack325amay be provided in a structure in which a (1-2)ndhole transport layer HTLa-2, a (1-2)ndemission layer EMLa-2, a (1-2)ndelectron transport layer ETLa-2, and the electron injection layer EIL are sequentially stacked.

The first charge generation layer322amay be located between the first stack321aand the (1-1)st stack323a, and a (1-1)st charge generation layer324amay be located between the (1-1)st stack323aand the (1-2)nd stack325a. The first charge generation layer322amay include the first n-type charge generation layer n-CGLa and the p-type charge generation layer p-CGL, and the (1-1)stcharge generation layer324amay include a (1-1)stn-type charge generation layer n-CGLa-1and another p-type charge generation layer p-CGL. In an embodiment, the first n-type charge generation layer n-CGLa and the (1-1)stn-type charge generation layer n-CGLa-1may include a same material.

Similarly, the second intermediate layer320bmay include the second stack321bincluding the second emission layer EMLb, the (2-1)ststack323bincluding the (2-1)stemission layer EMLb-1, a (2-2)ndstack325bincluding the (2-2)ndemission layer EMLb-2, and second and (2-1)stcharge generation layers322band324bbetween each stack. The (2-2)ndstack325bmay be provided in a structure in which a (2-2)ndhole transport layer HTLb-2, a (2-2)ndemission layer EMLb-2, a (2-2)ndelectron transport layer ETLb-2, and the electron injection layer EIL are sequentially stacked.

The second charge generation layer322bmay be located between the second stack321band the (2-1)ststack323b, and the (2-1)stcharge generation layer324bmay be located between the (2-1)ststack323band the (2-2)ndstack325b. The second charge generation layer322bmay include the second n-type charge generation layer n-CGLb and the p-type charge generation layer p-CGL, and the (2-1)stcharge generation layer324bmay include a (2-1)stn-type charge generation layer n-CGLb-1and another p-type charge generation layer p-CGL. In an embodiment, the second n-type charge generation layer n-CGLb and the (2-1)stn-type charge generation layer n-CGLb-1may include a same material.

Some elements of the first intermediate layer320aand the second intermediate layer320bmay include a same material. For example, the hole injection layer HIL and/or the electron injection layer EIL may be commonly applied to the first intermediate layer320aand the second intermediate layer320b.

In addition, as shown inFIG. 9, the first intermediate layer320aand one of stacks of the second intermediate layer320bmay include a same material. For example, the (2-1)ststack323bof the second intermediate layer320bmay be commonly applied to the first intermediate layer320aand the second intermediate layer320b. Accordingly, the first intermediate layer320aof the first organic light-emitting diode OLED1and the second organic light-emitting diode OLED2may include the first emission layer EMLa, the (2-1)stemission layer EMLb-1, and the (1-2)nd emission layer EMLa-2and the second intermediate layer320bof the third organic light-emitting diode OLED3may include the second emission layer EMLb, the (2-1)stemission layer EMLb-1, and the (2-2)ndemission layer EMLb-2. In an embodiment, each of the first emission layer EMLa and the (1-2)ndemission layer EMLa-2may include an organic material emitting green light, and each of the second emission layer EMLb, the (2-1)stemission layer EMLb-1, and the (2-2)ndemission layer EMLb-2may include an organic material emitting blue light.

In an embodiment, when the first intermediate layer320aand one of stacks of the second intermediate layer320binclude a same material, a process may be simplified.

InFIG. 9, the (2-1)ststack323bof the second intermediate layer320bis commonly applied to the first intermediate layer320aand the second intermediate layer320b, but the present disclosure is not limited thereto. Although not shown, the second stack321bor (2-2)ndstack325bof the second intermediate layer320bmay be commonly applied to the first intermediate layer320aand the second intermediate layer320b.

FIGS. 10 and 11are cross-sectional views schematically illustrating part of a display apparatus according to one or more embodiments. InFIGS. 10 and 11, the same reference symbols as those ofFIG. 4denote the same, and redundant descriptions thereof will be omitted for ease in explanation of the embodiment.

Referring toFIGS. 4 and 10, the emission area EA of the first to third organic light-emitting diodes OLED1, OLED2, and OLED3may be determined by the openings OP of the pixel-defining layer119a. In an embodiment, the bank119bmay be arranged on the pixel-defining layer119a.

The first and second intermediate layers320aand320bof the first to third organic light-emitting diodes OLED1, OLED2, and OLED3may be provided by stacking a plurality of emission layers. For example, the first intermediate layer320aof the first organic light-emitting diode OLED1and the second organic light-emitting diode OLED2may include the first emission layer EMLa and the (1-1)stemission layer EMLa-1, and the second intermediate layer320bof the third organic light-emitting diode OLED3may include the second emission layer EMLb and the (2-1)stemission layer EMLb-1.

The first hole transport layer HTLa may be arranged below the first emission layer EMLa, and the first electron transport layer ETLa may be arranged above the first emission layer EMLa. The (1-1)sthole transport layer HTLa-1may be arranged under the (1-1)stemission layer EMLa-1, and the (1-1)stelectron transport layer ETLa-1may be arranged above the (1-1)stemission layer EMLa-1. The first n-type charge generation layer n-CGLa may be arranged above the first electron transport layer ETLa, and the p-type charge generation layer p-CGL may be arranged above the first n-type charge generation layer n-CGLa.

The second hole transport layer HTLb may be arranged below the second emission layer EMLb, and the second electron transport layer ETLb may be arranged above the second emission layer EMLb. The (2-1)sthole transport layer HTLb-1may be arranged below the (2-1)stemission layer EMLb-1, and the (2-1)stelectron transport layer ETLb-1may be arranged above the (2-1)stemission layer EMLb-1. The second n-type charge generation layer n-CGLb may be arranged above the second electron transport layer ETLb, and the p-type charge generation layer p-CGL may be arranged on the second n-type charge generation layer n-CGLb.

In an embodiment, the bank119barranged on the pixel-defining layer119amay separate (disconnect) the first emission layer EMLa included in the first organic light-emitting diode OLED1and the second organic light-emitting diode OLED2from the second emission layer EMLb included in the third organic light-emitting diode OLED3. In addition, the bank119bmay separate (disconnect) the (1-1)stemission layer EMLa-1included in the first organic light-emitting diode OLED1and the second organic light-emitting diode OLED2from the (2-1)stemission layer EMLb-1included in the third organic light-emitting diode OLED3. In an embodiment, each of the first emission layer EMLa and (1-1)stemission layer EMLa-1may include an organic material emitting green light, and each of the second emission layer EMLb and the (2-1)stemission layer EMLb-1may include an organic material emitting blue light.

In some embodiments, as shown inFIG. 11, the p-type charge generation layer p-CGL, the (2-1)sthole transport layer HTLb-1, the (2-1)stemission layer EMLb-1, and the (2-1)stelectron transport layer ETLb-1may be provided as a single body with the first intermediate layer320aand the second intermediate layer320b. Meanwhile, the first hole transport layer HTLa and the second hole transport layer HTLb, the first emission layer EMLa and the second emission layer EMLb, and the first electron transport layer ETLa and the second electron transport layer ETLb may be separated (disconnected) from each other by the bank119b. In an embodiment, the first emission layer EMLa may include an organic material emitting green light, and each of the second emission layer EMLb and the (2-1)stemission layer EMLb-1may include an organic material emitting blue light.

As described above, in the display apparatus according to the embodiments of the present disclosure, emission layers and charge generation layers of a first sub-pixel and a second sub-pixel are applied differently from an emission layer and charge generation layer of a third sub-pixel, and thus, the power consumption is reduced and the lifespan of the organic light-emitting diode may increase.