Organic light-emitting device

An organic light-emitting device including a first sub-pixel, a second sub-pixel, and a third sub-pixel on a substrate; a plurality of first electrodes in the first sub-pixel, the second sub-pixel, and the third sub-pixel, respectively; a second electrode being a sub-common layer to the first sub-pixel and the second sub-pixel and facing the first electrodes of the first sub-pixel and the second sub-pixel; and a third electrode in the third sub-pixel and facing the first electrode of the third sub-pixel is disclosed.

CROSS-REFERENCE TO RELATED APPLICATION

This application claims priority to and the benefit of Korean Patent Application No. 10-2013-0121507, filed on Oct. 11, 2013, in the Korean Intellectual Property Office, the entire content of which is incorporated herein by reference.

BACKGROUND

One or more aspects according to embodiments of the present disclosure relate to an organic light-emitting device.

2. Description of the Related Art

Organic light-emitting devices (OLEDs), which are self-emitting devices, have advantages such as wide viewing angles, excellent contrast, quick response, high brightness, excellent driving voltage characteristics, and can provide multicolored images.

An organic light-emitting device may have a structure in which a first electrode, a hole transport layer (HTL), an emission layer (EML), an electron transport layer (ETL), and a second electrode are sequentially, in that order, on a substrate. Holes injected from the first electrode move to the EML via the HTL, while electrons injected from the second electrode move to the EML via the ETL. The holes and electrons recombine in the EML to generate excitons. When the excitons transition from an excited state to a ground state, light is emitted.

SUMMARY

One or more aspects according to embodiments of the present disclosure are directed toward a high-efficiency organic light-emitting device (OLED) with a low occurrence rate of progressive dark spots.

According to one or more embodiments of the present disclosure, an organic light-emitting device includes:

a first sub-pixel, a second sub-pixel, and a third sub-pixel on a substrate;

a plurality of first electrodes in the first sub-pixel, the second sub-pixel, and the third sub-pixel, respectively;

a second electrode being a sub-common layer to the first sub-pixel and the second sub-pixel and facing the first electrodes of the first sub-pixel and the second sub-pixel;

a third electrode in the third sub-pixel and facing the first electrode of the third sub-pixel; and

an organic layer including a first emission unit between the first electrode and the second electrode of the first sub-pixel and configured to emit a light of a first color, a second emission unit between the first electrode and the second electrode of the second sub-pixel and configured to emit a light of a second color, and a third emission unit between the first electrode and the third electrode of the third sub-pixel and configured to emit a light of a third color,

wherein the light of the third color is blue light, and a mixed light of the light of the first color, the light of the second color, and the light of the third color is white light, and

i) the second electrode is substantially free of magnesium (Mg) and the third electrode includes magnesium (Mg); or ii) the second electrode and the third electrode both include magnesium (Mg) according to Formula 1:
Con2(Mg)<Con3(Mg)  Formula 1

Con2(Mg) is a ratio, by percent, of a volume of magnesium (Mg) in the second electrode to a volume of the second electrode, and

Con3(Mg) is a ratio, by percent, of a volume of magnesium (Mg) in the third electrode to a volume of the third electrode.

The second electrode and the third electrode both may include silver (Ag) according to Formula 2:
Con2(Ag)>Con3(Ag)  Formula 2

Con2(Ag) is a ratio, by percent, of a volume of silver (Ag) in the second electrode to the volume of the second electrode, and

Con3(Ag) is a ratio, by percent, of a volume of silver (Ag) in the third electrode to the volume of the third electrode.

The second electrode and the third electrode further each independently may include a first metal, and the first metal includes at least one selected from silver (Ag), copper (Cu), gold (Au), zinc (Zn), aluminum (Al), and indium (In).

The second electrode and the third electrode further each independently may include a first material having a work function of about 4.0 eV or less, and the first material includes at least one selected from ytterbium (Yb), lithium (Li), sodium (Na), potassium (K), rubidium (Rb), cesium (Cs), calcium (Ca), strontium (Sr), barium (Ba), radium (Ra), scandium (Sc), yttrium (Y), lanthanum (La), cerium (Ce), ruthenium (Ru), and samarium (Sm).

The second electrode and the third electrode further each independently may include a second material as an electron injection material, and the second material includes at least one selected from an oxide, a fluoride, a quinolate compound, and an acetoacetate compound of an alkali metal and an alkali earth metal.

The second electrode may consist of silver (Ag) and the third electrode may consist of silver (Ag) and magnesium (Mg).

A thickness of the second electrode may be different from a thickness of the third electrode.

The light of the first color may be red light, the light of the second color may be green light, and the organic light-emitting device may satisfy Formula 3:
D1≧D2>D3Formula 3

D1is a distance between the first electrode and the second electrode in the first sub-pixel,

D2is a distance between the first electrode and the second electrode in the second sub-pixel, and

D3is a distance between the first electrode and the third electrode in the third sub-pixel.

The organic light-emitting may further include a first electron injection layer between the second electrode and the first and second emission units, the first electron injection layer being a sub-common layer to the first sub-pixel and the second sub-pixel; and a second electron injection layer between the third electrode and the third emission unit in the third sub-pixel, wherein the first electron injection layer and the second electron injection layer include materials different from each other.

The first electron injection layer may include a first material having a work function of about 4.0 eV or less, the first material including at least one selected from ytterbium (Yb), lithium (Li), sodium (Na), potassium (K), rubidium (Rb), cesium (Cs), calcium (Ca), strontium (Sr), barium (Ba), radium (Ra), scandium (Sc), yttrium (Y), lanthanum (La), cerium (Ce), ruthenium (Ru), and samarium (Sm), and the second electron injection layer includes a second material as an electron injection material, the second material including at least one selected from an oxide, a fluoride, a quinolate compound, and an acetoacetate compound of an alkali metal and an alkali earth metal.

The organic light-emitting device may further include an electron injection layer as a sub-common layer to the first sub-pixel, the second sub-pixel, and the third sub-pixel.

An edge portion of the second electrode and an edge portion of the third electrode in the third sub-pixel adjacent to the second sub-pixel may be electrically coupled together, and one of the edge portion of the second electrode and the edge portion of the third electrode overlaps the other of the edge portion of the second electrode and the edge portion of the third electrode.

The substrate may include a first transistor electrically coupled to the first electrode of the first sub-pixel; a second transistor electrically coupled to the first electrode of the second sub-pixel; and a third transistor electrically coupled to the first electrode of the third sub-pixel.

According to one or more embodiments of the present disclosure, an organic light-emitting device includes:

a first sub-pixel, a second sub-pixel, and a third sub-pixel on a substrate;

a plurality of first electrodes in the first sub-pixel, the second sub-pixel, and the third sub-pixel, respectively;

a second electrode being a sub-common layer to the first sub-pixel and the second sub-pixel and facing the first electrodes of the first sub-pixel and the second sub-pixel;

a third electrode in the third sub-pixel and facing the first electrode of the third sub-pixel; and

an organic layer including a first emission unit between the first electrode and the second electrode of the first sub-pixel and configured to emit a light of a first color, a second emission unit between the first electrode and the second electrode of the second sub-pixel and configured to emit a light of a second color, and a third emission unit between the first electrode and the third electrode of the third sub-pixel and configured to emit a light of a third color,

wherein the light of the third color is blue light, and a mixed light of the light of the first color, the light of the second color, and the light of the third color is white light, and

an edge portion of the second electrode and an edge portion of the third electrode in the third sub-pixel adjacent to the second sub-pixel are electrically coupled together and one of the edge portion of the second electrode and the edge portion of the third electrode overlaps the other of the edge portion of the second electrode and the edge portion of the third electrode.

In some embodiments, an edge portion of the second electrode and an edge portion of the third electrode in the third sub-pixel adjacent to the second sub-pixel may be electrically coupled together without overlapping with each other.

DETAILED DESCRIPTION

Reference will now be made to embodiments, examples of which are illustrated in the accompanying drawings, wherein like reference numerals refer to the like elements throughout. In this regard, the present embodiments may have different forms and should not be construed as being limited to the descriptions set forth herein. Accordingly, the embodiments are merely described below, by referring to the figures, to illustrate and explain aspects of the present description. As used herein, the term “and/or” includes any and all combinations of one or more of the associated listed items. Expressions such as “at least one of,” when preceding a list of elements, modify the entire list of elements and do not modify the individual elements of the list. Further, the use of “may” when describing embodiments of the present disclosure refers to “one or more embodiments of the present disclosure.” Also, in the context of the present application, when a first element is referred to as being “on” a second element, it can be directly on the second element or be indirectly on the second element with one or more intervening elements interposed therebetween.

Referring toFIG. 1, an organic light-emitting device400according to an embodiment of the present disclosure includes: a first sub-pixel, a second sub-pixel, and a third sub-pixel on a substrate201; a plurality of first electrodes203-1,203-2, and203-3in the first sub-pixel, the second sub-pixel, and the third sub-pixel on the substrate201, respectively; a second electrode217in common with (e.g., as a sub-common layer to) the first sub-pixel and the second sub-pixel (e.g., coupled to or in both the first sub-pixel and the second sub-pixel) and opposite to (e.g., facing) the first electrodes203-1and203-2of the first sub-pixel and the second sub-pixel respectively; a third electrode219in the third sub-pixel and opposite to (e.g., facing) the first electrode203-3of the third sub-pixel; and an organic layer207including a first emission unit207-1between the first electrode203-1and the second electrode217of the first sub-pixel and capable of emitting a light of a first color (e.g., a light having a single first color), a second emission unit207-2between the first electrode203-2and the second electrode217of the second sub-pixel and capable of emitting a light of a second color (e.g., a light having a single second color), and a third emission unit207-3between the first electrode203-3and the third electrode219of the third sub-pixel and capable of emitting a light of a third color (e.g., a light having a single third color).

In the organic light-emitting device400, the light of the third color may be blue light, and a mixed light of the light of the first color, the light of the second color, and the light of the third color may be white light. Accordingly, the organic light-emitting device400may emit light in full color. In some embodiments, the light of the first color may be red light, while the light of the second color may be green light. In some other embodiments, the light of the first color may be green light, while the light of the second color may be red light. However, the present disclosure is not limited thereto, and embodiments of the present disclosure may be implemented in different forms and/or arrangements.

As used herein, the term “common layer” refers to a layer that is over (or under, depending upon the point of view, or in) the first sub-pixel, the second sub-pixel, and the third sub-pixel, and is not patterned into individual layers respectively corresponding to the first sub-pixel, the second sub-pixel, and the third sub-pixel. In addition, as used herein, the term “sub-common layer to the first sub-pixel and the second sub-pixel” refers to a layer that is over (or under, depending upon the point of view, or in) the first sub-pixel and the second sub-pixel, and is not pattered into individual layers respectively corresponding to the first sub-pixel and the second sub-pixel.

The substrate201may be any suitable substrate that is used in existing organic light-emitting devices. In some embodiments, the substrate201may be a glass substrate or a transparent plastic substrate having strong mechanical strength, thermal stability, transparency, surface smoothness, ease of handling, and water resistance, but the present disclosure is not limited thereto.

The first electrodes203-1,203-2, and203-3may be formed on the substrate201to correspond to the first sub-pixel, the second sub-pixel, and the third sub-pixel, respectively, via patterning. The first electrodes203-1,203-2, and203-3may be reflective electrodes, transmissive electrodes, or semi-transmissive electrodes.

The first electrodes203-1,203-2, and203-3may be formed by depositing or sputtering a first electrode forming material onto the substrate201. When the first electrodes203-1,203-2, and203-3are anodes, the first electrode forming material may be selected from materials having high work functions to facilitate injection of holes into the first emission unit207-1, the second emission unit207-2, and the third emission unit207-3.

The first electrodes203-1,203-2, and203-3may include at least one metal, for example, magnesium (Mg), aluminum (Al), aluminum-lithium (Al—Li), calcium (Ca), magnesium-indium (Mg—In), and/or magnesium-silver (Mg—Ag) to form reflective electrodes, but the present disclosure is not limited thereto. In some other embodiments, the first electrodes203-1,203-2, and203-3may further include, in addition to the above-listed metals, a transparent material having high conductivity, for example, indium tin oxide (ITO), indium zinc oxide (IZO), tin oxide (SnO2), and/or zinc oxide (ZnO). However, the present disclosure is not limited thereto and embodiments of the present disclosure may be implemented in other different forms and/or arrangements.

The first electrodes203-1,203-2, and203-3may each have a single-layer structure or a multi-layer structure.

For example, the first electrodes203-1,203-2, and203-3may have a three-layered structure of indium tin oxide (ITO)/Ag/indium tin oxide (ITO), but the first electrodes are not limited thereto.

The first electrodes203-1,203-2, and203-3may have pixel defining layers205along opposite edge portions thereof. The pixel defining layers205may define pixel regions, and may include any of a variety of suitable insulating materials used in organic light-emitting devices, such as an organic insulating material (for example, a silicon-based material), an inorganic insulating material, or an organic/inorganic composite insulating material, but the present disclosure is not limited thereto.

The organic layer207is on the first electrode203-1,203-2, and203-3.

The organic layer207may include at least one layer selected from a hole injection layer (HIL), a hole transport layer (HTL), a buffer layer, an emission layer (EML), a hole blocking layer (HBL), and an electron transport layer (ETL). The HIL, the HTL, the buffer layer, the EML, the HBL, and the ETL may each be formed as a common layer extending over the first sub-pixel, the second sub-pixel, and the third sub-pixel, or as individual layers (e.g., separate layers) respectively corresponding to the first sub-pixel, the second sub-pixel, and the third sub-pixel, via patterning.

The organic layer207may include: the first emission unit207-1between the first electrode203-1and the second electrode217of the first sub-pixel and capable of emitting a light of a first color (e.g., a light having a single first color), the second emission unit207-2between the first electrode203-2and the second electrode217of the second sub-pixel and capable of emitting a light of a second color (e.g., a light having a single second color), and the third emission unit207-3between the first electrode203-3and the third electrode219of the third sub-pixel and capable of emitting a light of a third color (e.g., a light having single third color).

When the light of the first color is red light, and the light of the second color is green light, the organic light-emitting device400may satisfy Formula 3:
D1≧D2>D3Formula 3

In Formula 3, D1is a distance between the first electrode203-1and the second electrode217of the first sub-pixel, D2is a distance between the first electrode203-2and the second electrode217of the second sub-pixel, and D3is a distance between the first electrode203-3and the third electrode219of the third sub-pixel.

When the organic light-emitting device400satisfies the condition of Formula 3, a resonance distance for a wavelength of each of the light of the first color, the light of the second color and/or the light of the third color may be ensured (or provided) in each of the first, second, and third sub-pixels, and thus the organic light-emitting device400may have improved emission efficiency.

The organic light-emitting device400may include the second electrode217, which is in common with (e.g., in both) the first sub-pixel and the second sub-pixel (e.g., as a sub-common layer), opposite to (e.g., facing) the first electrodes203-1and203-2of the first sub-pixel and the second sub-pixel, respectively. The organic light-emitting device400may further include the third electrode219, which is in the third sub-pixel, opposite to (e.g., facing) the first electrode203-3of the third sub-pixel.

In some embodiments, the second electrode217of the organic light-emitting device400does not include magnesium (Mg), and the third electrode219may include magnesium (Mg). For example, in some embodiments the second electrode217is substantially free from Mg. As used herein, the term “substantially” is used as a term of approximation, and not as a term of degree. In particular, as used herein, “substantially free from Mg” refers to the absence of most Mg, but some trace amount of Mg may be present. In some embodiments, the second electrode217is completely free of Mg.

In some embodiments, the second electrode217and the third electrode219of the organic light-emitting device400may both include magnesium (Mg) according to Formula 1 below.
Con2(Mg)<Con3(Mg)  Formula 1

In Formula 1, Con2(Mg) is a ratio, by percent (e.g., volume percent), of a volume of magnesium (Mg) in the second electrode217to a total volume of the second electrode217, and Con3(Mg) is a ratio, by percent (e.g., volume percent), of a volume of magnesium (Mg) in the third electrode219to a total volume of the third electrode219.

The Con3(Mg) in the third electrode219may be about 55% by volume to about 95% by volume, but the third electrode is not limited thereto. For example, the third electrode219may be an electrode formed by co-depositing Mg and Ag in a volume ratio of about 9:1.

When the organic light-emitting device400satisfies the condition of Formula 3 where D3is the smallest among D1, D2, and D3, the third emission unit207-3of the third sub-pixel is most likely to be damaged from diffusion of metal of the third electrode219to the organic layer207. Accordingly, an occurrence rate of progressive dark spots in the third sub-pixel of the organic light-emitting device400may be relatively higher than those in the first sub-pixel and the second sub-pixel.

However, since Mg is an element that may not be substantially diffused into the organic layer207, when only the third electrode219of the organic light-emitting device400includes magnesium (Mg) (e.g., the second electrode217is free or substantially free of Mg) or the organic light-emitting device400satisfies the condition of Formula 1, the relatively higher occurrence rate of progressive dark spots in the third sub-pixel may be reduced.

Therefore, the first sub-pixel, the second sub-pixel, and the third sub-pixel of the organic light-emitting device400may all have low occurrence rates of progressive dark spots, and thus the organic light-emitting device400as a full color display may have an improved lifetime.

In some embodiments, the second electrode217and the third electrode219of the organic light-emitting device400may both include silver (Ag) according to Formula 2 below.
Con2(Ag)>Con3(Ag)  Formula 2

In Formula 2, Con2(Ag) is a ratio, by percent (e.g., volume percent), of a volume of silver (Ag) in the second electrode217to the total volume of the second electrode217, and Con3(Ag) is a ratio, by percent (e.g., volume percent), of a volume of silver (Ag) in the third electrode219to the total volume of the third electrode219.

The Con2(Ag) in the second electrode217may be about 55% by volume to about 100% by volume, but the second electrode is not limited thereto. For example, the second electrode217may exclusively include Ag. In some embodiments, the second electrode217consists of or consists essentially of silver. In some other embodiments, the Con2(Ag) in the second electrode217may be about 55% by volume to about 95% by volume. For example, the second electrode217may be an electrode formed by co-depositing Ag and Mg in a volume ratio of about 9:1.

Silver (Ag) is an element with high conductivity facilitating charge injection, and apt to be diffused into the organic layer207. For example, under the same (or substantially the same) conditions, a diffusion rate of Ag may be higher than that of Mg. Therefore, when the organic light-emitting device400satisfies the condition of Formula 2, the first sub-pixel and the second sub-pixel may have high emission efficiencies, while there may occur less diffusion of Ag from the third electrode219into the third emission unit207-3in the third sub-pixel where the occurrence rate of progressive dark spots is otherwise relatively higher, as compared to the first sub-pixel and the second sub-pixel. Thus, the organic light-emitting device400may have an improved lifetime as a full color display.

The second electrode217and the third electrode219may further each independently include a first metal, in addition to magnesium (Mg). The first metal may include at least one selected from silver (Ag), copper (Cu), gold (Au), zinc (Zn), aluminum (Al), and indium (In).

When the second electrode217and the third electrode219further includes the first metal, the type (kind) and amount of the first metal in the second electrode217may be the same as or different from those of the first metal in the third electrode219. When the second electrode217and the third electrode219both include silver (Ag) as the first metal, the organic light-emitting device400may satisfy the condition of Formula 2.

The second electrode217and the third electrode219may further each independently include a first material having a work function of about 4.0 eV or less. The first material may include at least one selected from ytterbium (Yb), lithium (Li), sodium (Na), potassium (K), rubidium (Rb), cesium (Cs), calcium (Ca), strontium (Sr), barium (Ba), radium (Ra), scandium (Sc), yttrium (Y), lanthanum (La), cerium (Ce), ruthenium (Ru), and samarium (Sm),

When the second electrode217and the third electrode219further each independently includes the first material, the type and amount of the first material in the second electrode217may be the same as or different from those of the first material in the third electrode219.

The second electrode217and the third electrode219may further each independently include a second material as an electron injection material. The second material may include at least one selected from an oxide, a fluoride, a quinolate compound, and an acetoacetate compound of an alkali metal and an alkali earth metal. For example, the second material may include at least one selected from LiF, CsF, Li2O, BaO, and lithium quinolate (Liq).

When the second electrode217and the third electrode219further includes the second material, the type and amount of the second material in the second electrode217may be the same as or different from those of the second material in the third electrode219.

In some embodiments, the second electrode217may include (e.g., consist of) silver (Ag), and the third electrode219may include (e.g., consist of) silver (Ag) and magnesium (Mg). In this regard, the Con3(Mg) of the third electrode219may be about 55% by volume to about 95% by volume.

An edge portion of the second electrode217may have an overlapping region OV1in which an edge portion of the second electrode217may be electrically connected to (e.g., electrically coupled to), and overlapping with, an edge portion of the third electrode219in the third sub-pixel adjacent to the second sub-pixel.

In the overlapping region OV1ofFIG. 1, the edge portion of the second electrode217is under the edge portion of the third electrode219, but embodiments of the present disclosure are not limited thereto. For example, the edge portion of the second electrode217may be over the edge portion of the third electrode219.

The presence of the overlapping region OV1may reduce sheet resistances of the second electrode217and the third electrode219, so that a rate of charge injection into the organic layer207may be improved, and thus the organic light-emitting device400may have improved emission efficiency.

In the organic light-emitting device400ofFIG. 1, at least one of the edge portion of the third electrode219and the edge portion of the second electrode217may extend to a non-emission region C between an emission region B of the third sub-pixel and an emission region A of the second sub-pixel adjacent to the third sub-pixel. In this embodiment, the edge portion of the third electrode219does not extend to an emission region A of the adjacent second sub-pixel, and the edge portion of the second electrode217does not extend to the emission region B of the adjacent third sub-pixel.

In the organic light-emitting device400ofFIG. 1, thicknesses of the second electrode217and the third electrode219may be the same as or different from each other. In some embodiments, the thicknesses of the second electrode217and the third electrode219may be different from each other.

A method of manufacturing the organic light-emitting device100ofFIG. 1, according to an embodiment of the present disclosure, will be described with reference toFIGS. 2A to 2C.

Referring toFIG. 2A, a plurality of first electrodes203-1,203-2, and203-3in a first sub-pixel, a second sub-pixel, and a third sub-pixel on a substrate201, respectively; a pixel defining layer205; and an organic layer207including a first emission unit207-1for emitting a light of a first color (e.g., a light having a single first color), a second emission unit207-2for emitting a light of a second color (e.g., a light having a single second color), and a third emission unit207-3for emitting light of a third color (e.g., a light having a single third color) may be sequentially formed on a substrate201.

Next, as illustrated inFIG. 2B, a second electrode217may be formed on a region of the organic layer207that corresponds to the first sub-pixel and the second sub-pixel by using (utilizing) a first mask500having an opening corresponding to the first sub-pixel and the second sub-pixel.

The second electrode217may be formed using any suitable deposition method used for forming electrodes of organic light-emitting devices. A material for the second electrode217may be a material as described above. When the second electrode217includes materials that are different from each other, the second electrode217may be formed using co-deposition.

An edge portion of the second electrode217may extend to a non-emission region C, but without extending to an emission region B of the adjacent third sub-pixel.

Next, as illustrated inFIG. 2C, a third electrode219may be formed on a region of the organic layer207that corresponds to the third sub-pixel by using a second mask501having an opening corresponding to the third sub-pixel.

The third electrode219may be formed using any suitable deposition method used for forming electrodes of organic light-emitting devices. A material for the third electrode219may be a material as described above. When the third electrode219includes materials that are different from each other, the third electrode219may be formed using co-deposition.

An edge portion of the third electrode219may extend to the non-emission region C, but without extending to an emission region A of the adjacent second sub-pixel.

Accordingly, an overlapping region OV1, in which respective edge portions of the second electrode217and the third electrode219are overlapped, is formed.

In the embodiment illustrated inFIGS. 2B and 2C, the forming of the second electrode217is followed by the forming of the third electrode219, but embodiments of the present disclosure are not limited thereto. For example, the forming of the third electrode219may be followed by the forming of the second electrode217.

FIG. 3is a schematic cross-sectional view of an organic light-emitting device401according to another embodiment of the present disclosure.

Referring toFIG. 3, regarding a substrate201, a pixel defining layer205, an organic layer207, D1, D2, and D3in an organic light-emitting device401, the above-detailed descriptions of the substrate201, the pixel defining layer205, the organic layer207, D1, D2, and D3in the organic light-emitting device400ofFIG. 1may be referred to.

The above-detailed descriptions of the second electrode217and the third electrode219of the organic light-emitting device400ofFIG. 2may be mostly referred to herein for understanding a second electrode317and a third electrode319of the organic light-emitting device401inFIG. 3, except that an edge portion of the second electrode317and an edge portion of the third electrode319in a third sub-pixel adjacent to a second sub-pixel are electrically connected (e.g., electrically coupled) without overlapping with each other.

At least one of the edge portion of the third electrode319and the edge portion of the second electrode317in the organic light-emitting device401may extend to a non-emission region C between an emission region B of the third sub-pixel and an emission region A of the second sub-pixel adjacent to the third sub-pixel. In this embodiment, the edge portion of the third electrode319does not extend to the emission region of the adjacent second sub-pixel, and the edge portion of the second electrode317does not extend to the emission region B of the adjacent sub-pixel.

FIG. 4is a schematic cross-sectional view of an organic light-emitting device402according to another embodiment of the present disclosure.

The above-detailed descriptions of the organic light-emitting device400ofFIG. 1may be mostly referred to herein for understanding the organic light-emitting device402ofFIG. 4, except that i) the organic light-emitting device402further includes a first electron injection layer215-2between the second electrode217and the first and second emission units207-1and207-2as a common layer of the first sub-pixel and the second sub-pixel, and a second electron injection layer215-3between the third emission unit207-3and the third electrode219in the third sub-pixel, and that ii) the organic light-emitting device402further includes a thin film transistor (TFT) in a substrate201.

In the organic light-emitting device402ofFIG. 4, the first electron injection layer215-2may directly contact (e.g., physically contact) the second electrode217, which is on the first injection layer215-2, and the second electron injection layer215-3may directly contact (e.g., physically contact) the third electrode219, which is also on the second electron injection layer215-3.

A material of the first electron injection layer215-2may be different from a material of the second electron injection layer215-3.

For example, the first electron injection layer215-2may include a first material having a work function of about 4.0 eV or less, but the first material is not limited thereto. The first material may include at least one selected from ytterbium (Yb), lithium (Li), sodium (Na), potassium (K), rubidium (Rb), cesium (Cs), calcium (Ca), strontium (Sr), barium (Ba), radium (Ra), scandium (Sc), yttrium (Y), lanthanum (La), cerium (Ce), ruthenium (Ru), and samarium (Sm), but the first material is not limited thereto.

The second electron injection layer215-3may include a second material as an electron injection material. The second material may include at least one selected from an oxide, a fluoride, a quinolate compound, and an acetoacetate compound of an alkali metal and an alkali earth metal, but the second material is not limited thereto. For example, the second electron injection layer215-3may include at least one selected from LiF, CsF, Li2O, BaO, and lithium quinolate (Liq), but the second electron injection layer is not limited thereto.

The first electron injection layer215-2may be formed on the organic layer207after placing the first mask500described with reference toFIG. 2Bon the organic layer207and before forming the second electrode217.

The second electron injection layer215-3may be formed on the organic layer207after placing the second mask501described with reference toFIG. 2Con the organic layer207and before forming the third electrode219.

Referring toFIG. 4, the substrate201of the organic light-emitting device402may include a first transistor TFT1electrically connected to (e.g., coupled to) a first electrode203-1of the first sub-pixel, a second transistor TFT2electrically connected to (e.g., coupled to) a first electrode203-2of the second sub-pixel, and a third transistor TFT3electrically connected to (e.g., coupled to) a first electrode203-3of the third sub-pixel. Accordingly, the organic light-emitting device402may be an active matrix organic light-emitting device.

The first electrode203-1of the first sub-pixel may be electrically connected to (e.g., coupled to) one of source and drain electrodes of the first transistor TFT1, the first electrode203-2of the second sub-pixel may be electrically connected to (e.g., coupled to) one of source and drain electrodes of the second transistor TFT2, and the first electrode203-3of the third sub-pixel may be electrically connected to (e.g., coupled to) one of source and drain electrodes of the third transistor TFT3.

Although the organic light-emitting devices according to embodiments of the present disclosure are described above with reference toFIGS. 1,2A,2B,2C,3, and4, embodiments of the present disclosure are not limited thereto. For example, the organic light-emitting device400ofFIG. 1may further include an electron injection layer between the organic layer207and the second and third electrodes217and219, as a common layer of the first sub-pixel, the second sub-pixel, and the third sub-pixel. The electron injection layer as a common layer of the first sub-pixel, the second sub-pixel, and the third sub-pixel may include at least one of a first material having a work function of about 4.0 eV or less, and a second material as an electron injection material.

In some embodiments, the organic light-emitting device400ofFIG. 1may further include transistors TFT1, TFT2, and TFT3as illustrated inFIG. 4, but embodiments of the organic light-emitting device400are not limited thereto.

In the organic light-emitting devices400,401, and402ofFIGS. 1,3, and4, the first electrodes203-1,203-2, and203-3may be anodes, and the second electrodes217and317and the third electrodes219and319may be cathodes. In some other embodiments, the first electrodes203-1,203-2, and203-3may be cathodes, and the second electrodes217and317and the third electrodes219and319may be anodes.

A performance test on organic light-emitting devices OLED1, OLED2, and OLED3that were manufactured as described below, was performed to observe efficiency and occurrence rate of dark spots of the organic light-emitting devices.

Anodes and organic layers of the organic light-emitting devices OLED1, OLED2, and OLED3were manufactured as follows. First, after an ITO/Ag/ITO anode (a first electrode) was formed on a glass substrate as a pattern corresponding to each of a first sub-pixel (capable of emitting red light), a second sub-pixel (capable of emitting green light), and a third sub-pixel (capable of emitting blue light), a pixel defining layer was formed to define pixel regions, and a hole injection layer and a hole transport layer as common layers of the first, second, and third sub-pixels were formed on the anode. After forming a first buffer layer and a red emission layer in the first sub-pixel, a second buffer layer and a green emission layer in the second sub-pixel, and a blue emission layer in the third sub-pixel via patterning, an electron transport layer was formed thereon as a common layer of the first, second, and third sub-pixels. The above-described structures of the anode and the organic layers were the same among the organic light-emitting devices OLED1, OLED2, and OLED3.

Next, an electron injection layer and a cathode were formed on the resultant structure including the anode and the organic layers described above to provide structures as set forth in Table 1, followed by forming a capping layer on the cathode, thereby completing the manufacture of the organic light-emitting devices OLED1, OLED2, and OLED3.

The second electrode, the third electrode, the first electron injection layer, and the second electron injection layer of the organic light-emitting device OLED1had the same (or substantially the same) structure as the second electrode217, the third electrode219, the first electron injection layer215-2, and the second electron injection layer215-3of the organic light-emitting device402ofFIG. 4.

White-light emission efficiencies of the organic light-emitting devices OLED1and OLED2were evaluated using a Kethley Source-Measure Unit (SMU) 236 and a PR650 Spectroscan (available from Photo Research, Inc.). The white-light emission efficiencies of the organic light-emitting devices OLED1and OLED2were found to be about 16.9 cd/A and about 14.8 cd/A, respectively.

An occurrence rate of dark spots in each of the organic light-emitting devices OLED1and OLED3, represented as [(Number of dark spots)/(Number of cells)×100(%)], was calculated after each organic light-emitting device was operated at a temperature of about −20° C. and a relative humidity of about 0% for about 120 hours at 300 nit (1 nit being equal to one candle per square meter). The occurrence rates of dark spots in the organic light-emitting devices OLED1and OLED3were found to be about 18.41% and about 21.82%, respectively.

These results indicate that the organic light-emitting device OLED1had an improved lifetime and improved efficiency compared to the other organic light-emitting devices OLED2and OLED3.

As described above, according to the one or more of the above embodiments, an organic light-emitting device may have high improved efficiency and a long lifetime.