KR20230164641A - Organic light emitting display device having a micro cavity structure - Google Patents

Abstract

The present invention discloses an organic electroluminescent display device. The organic electroluminescent display device of the disclosed invention includes a first electrode divided into red (R), green (G), and blue (B) sub-pixel areas; A first light emitting unit including a hole injection layer, a first hole transport layer, a first organic light emitting layer, and a first electron transport layer on the first electrode; a second light-emitting unit including a second hole transport layer, a second organic light-emitting layer, and a second electron transport layer on the first light-emitting unit; and a second electrode disposed on the second light-emitting unit, wherein the distance between the first organic light-emitting layer and the second organic light-emitting layer is greater than the distance between the first electrode and the first organic light-emitting layer.
The organic electroluminescent display device having a micro-cavity structure of the present invention arranges two or more light-emitting layers in red (R), green (G), and blue (B) sub-pixel areas, and adjusts the distance between the light-emitting layers. It has the effect of improving light efficiency.

Description

Organic electroluminescent display device having a micro cavity structure {ORGANIC LIGHT EMITTING DISPLAY DEVICE HAVING A MICRO CAVITY STRUCTURE}

The present invention relates to an organic electroluminescent display device, and more specifically, to an organic electroluminescent display device having a micro cavity structure in which power consumption is reduced and light efficiency is improved by adjusting the distance between organic light emitting layers.

Recently, various flat panel display devices that can reduce the weight and volume, which are disadvantages of cathode ray tubes, are being developed.

In particular, the Organic Light Emitting Diode Display (Organic Light Emitting Diode Display) is a self-emitting display device that does not require a backlight like a liquid crystal display device, making it easier to make it lighter and thinner. Additionally, the process can be simplified and manufactured. And organic light-emitting diode displays have many advantages such as low-voltage operation, high luminous efficiency, and wide viewing angles, and are attracting attention as next-generation display devices.

The organic light emitting display device includes an organic light emitting diode, which is a self-light emitting device in which an organic light emitting layer is formed between two electrodes. Organic light-emitting diodes inject electrons and holes into the light-emitting layer from an electron (selection) injection electrode (cathode) and a hole (hole) injection electrode (anode), respectively, and exciton (exciton), which is a combination of the injected electrons and holes, is released from the excited state. It is a device that emits light when it falls to the ground state.

The organic electroluminescent display device using the organic light-emitting diode includes a top-emission method, a bottom-emission method, and a dual-emission method, depending on the direction in which light is emitted, and a driving method. Depending on the type, it is divided into passive matrix type and active matrix type.

Additionally, an organic light emitting display device can display an image by causing the selected sub-pixel to emit light when a scan signal, data signal, and power are supplied to each of a plurality of sub-pixels arranged in a matrix form.

Recently, in organic electroluminescent displays, the number of pixels per unit area of the display panel has increased in response to high-resolution requirements, and each pixel requires high luminance.

However, in order to implement a high-brightness organic light emitting display device, a high current must be applied to the organic light emitting diode, which increases power consumption and reduces device lifespan.

The present invention is an organic electric field having a micro-cavity structure that improves light efficiency by arranging two or more light-emitting layers in the red (R), green (G), and blue (B) sub-pixel areas and adjusting the distance between the light-emitting layers. The purpose is to provide a light emitting display device.

In addition, the present invention arranges two or more light-emitting layers in the red (R), green (G), and blue (B) sub-pixel areas, and adjusts the thickness of the organic material layers disposed above and below the light-emitting layers to produce a white color of the display panel. Another purpose is to provide an organic electroluminescent display device with a micro-cavity structure that improves light efficiency.

The organic electroluminescent display device of the present invention to solve the problems of the prior art as described above includes a first electrode divided into red (R), green (G), and blue (B) sub-pixel areas; A first light emitting unit including a hole injection layer, a first hole transport layer, a first organic light emitting layer, and a first electron transport layer on the first electrode; a second light-emitting unit including a second hole transport layer, a second organic light-emitting layer, and a second electron transport layer on the first light-emitting unit; and a second electrode disposed on the second light-emitting unit, wherein the distance between the first organic light-emitting layer and the second organic light-emitting layer is greater than the distance between the first electrode and the first organic light-emitting layer.

In addition, the organic electroluminescent display device of the present invention includes a first electrode divided into red (R), green (G), and blue (B) sub-pixel areas; A first light emitting unit including a hole injection layer, a first hole transport layer, a first organic light emitting layer, and a first electron transport layer on the first electrode; a second light-emitting unit including a second hole transport layer, a second organic light-emitting layer, and a second electron transport layer on the first light-emitting unit; and a second electrode disposed on the second light-emitting unit, wherein the distance between the first organic light-emitting layer and the second organic light-emitting layer is greater than the distance between the first electrode and the first organic light-emitting layer.

The organic electroluminescent display device having a micro-cavity structure of the present invention arranges two or more light-emitting layers in red (R), green (G), and blue (B) sub-pixel areas, and adjusts the distance between the light-emitting layers. It has the effect of improving light efficiency.

In addition, the organic electroluminescent display device having a micro-cavity structure of the present invention has two or more light-emitting layers arranged in red (R), green (G), and blue (B) sub-pixel areas, and disposed above and below the light-emitting layers. There is an effect of improving the efficiency of white light of the display panel by adjusting the thickness of the organic material layers.

1 is a diagram showing the structure of an organic light emitting display device according to an embodiment of the present invention.
Figures 2a and 2b are comparison tables of thickness values of the examples and comparative examples of the present invention.
Figure 3 is a diagram comparing the luminous efficiency characteristics of examples of the present invention and comparative examples.
Figure 4 is a graph comparing the device lifespan in the blue (B) pixel area for the embodiment of the present invention and comparative examples.
Figure 5 is a table of thickness values of other embodiments of the present invention and comparative examples.
Figure 6 is a diagram comparing light efficiency characteristics in the blue (B) pixel region for different embodiments of the present invention.
Figure 7 is a diagram comparing light efficiency characteristics in the green (B) pixel area for different embodiments of the present invention.
Figure 8 is a diagram comparing light efficiency characteristics in the red (R) pixel region for different embodiments of the present invention.

Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings. The embodiments introduced below are provided as examples so that the idea of the present invention can be sufficiently conveyed to those skilled in the art. Accordingly, the present invention is not limited to the embodiments described below and may be embodied in other forms. And in the drawings, the size and thickness of the device may be exaggerated for convenience. Like reference numerals refer to like elements throughout the specification.

The organic electroluminescent display device according to the present invention includes a timing control unit, a data driver, a scan driver, and a display panel.

The timing control unit receives vertical synchronization signals, horizontal synchronization signals, data enable signals, clock signals, and data signals from an external source, such as an image processing unit. The timing control unit controls the operation timing of the data driver and scan driver using timing signals such as a vertical synchronization signal, a horizontal synchronization signal, a data enable signal, and a clock signal.

The data driver samples and latches the data signal supplied from the timing control unit in response to the data timing control signal supplied from the timing control unit and converts it into a data signal of a parallel data system. The data driver converts the digital data signal into an analog data signal in a parallel data system in response to the gamma reference voltage. The data driver supplies the converted data signal to subpixels included in the display panel through data lines.

The scan driver sequentially generates scan signals in response to the gate timing control signal supplied from the timing control unit. The scan driver supplies scan signals generated through scan lines to subpixels included in the display panel.

The display panel includes subpixels arranged in a matrix form. The subpixels may be composed of red, green, and blue subpixels, or may be composed of a white subpixel and a color conversion layer that converts the white light of the white subpixel into red, green, and blue. Subpixels are either passive or active. For example, an active subpixel includes a switching transistor that supplies a data signal in response to a scan signal, a capacitor that stores the data signal as a data voltage, a driving transistor that generates a driving current in response to the data voltage, and emits light in response to the driving current. Organic light emitting diodes are included. Active subpixels may be composed of a 2T (Transistor) 1C (Capacitor) structure including a switching transistor, driving transistor, capacitor, and organic light-emitting diode, or may be composed of a structure with additional transistors or capacitors, such as 3T1C, 4T2C, 5T2C, etc. there is. Additionally, subpixels may be formed in a top-emission, bottom-emission, or dual-emission manner depending on their structure.

Meanwhile, the subpixels that make up the display panel are composed of a micro cavity or stack structure to improve luminous efficiency and color coordinates, which will be described in more detail as follows.

1 is a diagram showing the structure of an organic light emitting display device according to an embodiment of the present invention.

Referring to FIG. 1, the organic electroluminescent display device of the present invention includes a first electrode 110 serving as a reflective electrode on a substrate divided into red (R), green (G), and blue (B) sub-pixel regions. is formed on the first electrode 110, and a hole injection layer (HIL) 120 is formed as a common layer in the red (R), green (G), and blue (B) sub-pixel regions.

The first electrode 110 serves as an anode electrode of the organic light emitting diode, and is formed by forming ITO (Indium Tin Oxide) on the first metal film 110a with high reflectivity, such as aluminum (Al) or silver (Ag). , it may be composed of a second metal film 110b made of a transparent conductive material such as IZO (Indium Zinc Oxide).

The hole injection layer (HIL: 120) is composed of phthalocyanine compounds such as copper phthalocyanine, starburst type amines such as TCTA, m-MTDATA, and m-MTDAPB, or arylamine bases such as NATA, 2T-NATA, It may be selected from the group consisting of NPNPB, F4-TCNQ, which is a P-doped system, and PPDN.

The first thickness of the hole injection layer (HIL: 120) may be formed to a value of X1.

A first hole transport layer (HTL: 130) is stacked on the hole injection layer 120, and may be formed to a second thickness of X2.

The first hole transport layer (HTL: 130) is an arylamine base series (NPB (N,N-naphthyl-N,N'-phenyl benzidine), TPD (N,N'-bis-(3-methylphenyl )-N,N'-bis-(phenyl)-benzidine), PPD, TTBND, FFD, p-dmDPS, TAPC, and starbust aromatic amines such as TCTA, PTDATA, TDAPB, TDBA, 4 -a, TCTA, Spiro and Ladder Type substances (Spiro and Ladder Type) Spiro-TPD, Spiro-mTTB, Spiro-2, NPD (N,N-dinaphthyl-N,N'-diphenyl benzidine), s- It may be composed of one or more selected from the group consisting of TAD and MTDATA (4,4',4"-Tris(N-3-methylphenyl-N-phenyl-amino)-triphenylamine), but is not limited thereto.

On the first hole transport layer 130, a first organic light emitting layer 135 is formed in red (R), green (G), and blue (B) sub-pixel regions, respectively. An electron blocking layer (EBL: Electron Blocking Layer, not shown) may be formed between the first hole transport layer 130 and the first organic light-emitting layer 135, and the first organic light-emitting layer 135 may be formed between holes and electrons. By transporting and combining each, it can contain a material that can emit light in the visible light range.

The first organic light-emitting layer 135 includes a first red (R) light-emitting layer 135a, a first green (G) light-emitting layer ( It is formed separately into a first blue (B) emission layer 135b) and a first blue (B) emission layer 135c, and the thickness of each emission layer may be different from each other.

The first red (R) emission layer 135a in the red (R) sub-pixel area is formed to a thickness of 600 to 800 Å, and the first green (G) emission layer 135b in the green (G) sub-pixel area is formed with a thickness of 300 Å. It is formed to a thickness of ~500 Å, and the first blue (B) emission layer in the blue (B) sub-pixel region can be formed to a thickness of 100 to 300 Å.

Additionally, materials with good quantum efficiency for fluorescence or phosphorescence can be used as the material for the light-emitting layer. As a specific example of the light emitting layer material, the first red (R) light emitting layer 135a includes a host material containing CBP (carbazole biphenyl) or mCP (1,3-bis (carbazol-9-yl), and PIQIr ( acac)(bis(1-phenylsoquinoline)acetylacetonate iridium), PQIr(acac)(bis(1-phenylquinoline)acetylacetonate iridium), PQIr(tris(1-phenylquinoline)iridium), and PtOEP(octaethylporphyrin platinum). It may be made of a phosphorescent material containing one or more dopants, and alternatively, it may be made of a fluorescent material containing PBD:Eu(DBM)3(Phen) or Perylene, but is not limited thereto.

In the case of the first green (G) emission layer 135b, it includes a host material including CBP or mCP and a phosphorescent material including a dopant material including Ir(ppy)3 (fac tris(2-phenylpyridine)iridium). It may be made of a material, or alternatively, it may be made of a fluorescent material containing Alq3 (tris(8-hydroxyquinolino)aluminum), but is not limited thereto.

In the case of the first blue (B) emission layer 135c, it may be made of a phosphorescent material including a host material including CBP or mCP and a dopant material including (4,6-F2ppy)2Irpic, which includes Alternatively, it may be made of a fluorescent material containing any one selected from the group consisting of spiro-DPVBi, spiro-6P, distylbenzene (DSB), distrylarylene (DSA), PFO-based polymer, and PPV-based polymer, but is limited thereto. It doesn't work.

A first electron transport layer (ETL) 136 is formed on the first organic light-emitting layer 135, and first and second charge generation layers (CGL) are formed on the first electron transport layer 136. 151, 152) are stacked.

The first electron transport layer 136 may include an electron injection layer (EIL).

The third thickness of the first electron transport layer 136 may have a Y1 value, the fourth thickness of the first charge generation layer 151 may have a Y2 value, and the second charge generation layer 152 The fifth thickness may have a Y3 value.

The first electron transport layer 136 serves to facilitate the transport of electrons, and is at least one selected from the group consisting of Alq3 (tris(8-hydroxyquinolino)aluminum), PBD, TAZ, spiro-PBD, BAlq, and SAlq. It may consist of, but is not limited to this.

The first and second charge generation layers 151 and 152 are stacked on the first electron transport layer 136, and as in the present invention, the organic light emitting display device may include two or more light emitting layers. Additionally, each light-emitting layer functions as an organic light-emitting diode and can emit light.

The first and second charge generation layers 151 and 152 may include an n-type organic material layer and a p-type organic material layer, respectively. The first charge generation layer 151, which is an n-type charge generation layer, is disposed closer to the first electrode 110, and the second charge generation layer 152, which is a p-type charge generation layer, is disposed closer to the second electrode 140 to be formed later. ) is placed closer to the

The LUMO energy level of the first charge generation layer 151 has a value equal to or greater than the HOMO energy level of the second charge generation layer 152, and in this case, it is more effective in generating charges. The HOMO energy level refers to the distance from the vacuum level to the highest occupied molecular orbital. Additionally, the LUMO energy level refers to the distance from the vacuum level to the lowest unoccupied molecular orbital.

Charges may be generated by forming an NP junction structure between the first charge generation layer 151 and the second charge generation layer 152. The first and second charge generation layers 151 and 152 may not be formed in some cases.

In addition, the hole injection layer 120, the first hole transport layer 130, the first organic light-emitting layer 135, the first electron transport layer 136, and the first charge generation layer 151 are colored red (R), green ( Organic light-emitting diodes formed in the G) and blue (B) sub-pixel areas constitute the first light-emitting unit (First Unit).

On the second charge generation layer 152, a second hole transport layer 230, a second organic light emitting layer 235, and a second electron transport layer 240 are sequentially stacked, and the colors are red (R), green (G), and blue. (B) An organic light emitting diode formed in the sub-pixel area, forming a second light emitting unit. The second hole transport layer 230 has a sixth thickness Y4, and the second electron transport layer 240 has a seventh thickness E.

At least two or more light emitting units can be formed in the above structure.

In addition, the second organic light-emitting layer 235 is formed by dividing into a second red (R) light-emitting layer 235a, a second green (G) light-emitting layer 235b, and a second blue (B) light-emitting layer 235c, respectively. The thickness of the light emitting layers may have different thicknesses.

The thickness of the second red (R) light-emitting layer 235a, the second green (G) light-emitting layer 235b, and the second blue (B) light-emitting layer 235c is the same as that of the first red (R) light-emitting layer 135a and the first blue (B) light-emitting layer 235c. It may be the same as the thickness of the green (G) emission layer 135b and the first blue (B) emission layer 135c.

Additionally, the thickness of the first organic emission layer 135 and the second organic emission layer 235 may be different from each other.

The second electron transport layer 240 may be formed of the same material as the first electron transport layer 136, and the second hole transport layer 230 may be formed of the same material as the first hole transport layer 130.

Additionally, a second electrode 140 is formed on the second electron transport layer 240 of the second light emitting unit, and a capping layer (CPL: 150) is formed on the second electrode 140.

The second electrode 140 is a cathode electrode, and a material with a low work function, excellent conductivity, and low sheet resistance is used. Group 1 or 2 alkali metals, alkaline earth metals, and transition metals may be used. You can. For example, single-layer electrodes, multi-layer electrodes made of silver (Ag), aluminum (Al), magnesium (Mg), lithium (Li), calcium (Ca), lithium fluoride (LiF), ITO, IZO, etc., or a mixture thereof. It may consist of an electrode, but is not limited thereto.

Additionally, the capping layer 150 may be formed of a material such as NPD.

Additionally, in an embodiment of the present invention, the total thickness of the organic material layer in each red (R), green (G), and blue (B) sub-pixel region may have different values. Preferably, the thickness of the red (R) sub-pixel region may be 2500 to 3100 Å, the thickness of the green (G) sub-pixel region may be 2000 to 2700 Å, and the thickness of the blue (B) sub-pixel region may be 1500 to 2000 Å.

In addition, the hole injection layer 120, the first hole transport layer 130, the first electron transport layer 136, the first charge generation layer 151, the second charge generation layer 152, and the second hole transport layer 230 ), the second electron transport layer 240 is used as a common layer in the first light-emitting unit and the second light-emitting unit.

That is, the first and second red (R) emission layers 135a and 235a, and the first and second green (G) emission layers 135b for the first organic emission layer 135 and the second organic emission layer 235, respectively. 235b), the first and second blue (B) light emitting layers 135c and 235c may each be formed to have different thicknesses.

In addition, a first red light-emitting layer (135a) corresponding to the first organic light-emitting layer 135 of the first light-emitting unit, and a second red light-emitting layer (235a) corresponding to the second organic light-emitting layer 235 of the second light-emitting unit. The thickness can be formed differently. Likewise, the first and second green (G) light emitting layers 135b and 235b and the first and second blue (B) light emitting layers 135c and 235c may be formed to have different thicknesses.

As shown in Figure 1, in the embodiment of the present invention, the thickness (A) of the organic material layer disposed below the first organic light-emitting layer 135 and the distance between the first organic light-emitting layer 135 and the second organic light-emitting layer 235 Light efficiency was improved by adjusting the thickness (B) of the organic layer.

The thickness (A) of the organic material layer disposed below the first organic light-emitting layer 135 has a value smaller than the thickness (B) of the organic material layer disposed between the first and second organic light-emitting layers 135 and 235.

[Equation 1]

A<B, (A=X1+X2, B=Y1+Y2+Y3+Y4)

Here, when the first charge generation layer 151 and the second charge generation layer 152 are not formed, the thickness B of the organic material layer may be Y1+Y4.

Implementing the micro cavity structure as described above increases the white efficiency of the display panel, which is achieved in the blue (B) sub-pixel area among the red (R), green (G) and blue (B) sub-pixel areas. In particular, this is because light extraction efficiency increases.

FIGS. 2A and 2B are comparison tables of thickness values of the examples of the present invention and comparative examples, FIG. 3 is a diagram comparing the luminous efficiency characteristics of the examples of the present invention and the comparative examples, and FIG. 4 is an example of the present invention. This is a graph comparing the device lifespan in the blue (B) pixel area for and comparative examples.

Referring to Figures 2A to 4 along with Figure 1, the organic electroluminescent display device according to an embodiment of the present invention has a first thickness of the hole injection layer (HIL: 120) disposed below the first organic light emitting layer 135. is formed to a value of X1 (Å), and the second thickness of the first hole transport layer (HTL: 130) is formed to a value of X2 (Å).

In addition, the third thickness of the first electron transport layer 136 disposed on the first organic light-emitting layer 135 has a Y1 (Å value, and the fourth thickness of the first charge generation layer 151 is Y2 ( It has an Å value, the fifth thickness of the second charge generation layer 152 has a Y3 (Å value), and the sixth thickness of the second hole transport layer 230 has a Y4 (Å value).

In Comparative Example 1, X1 is 50ÅX2 is 700Å, Y1 is 100ÅY2 is 100Å, Y3 is 50ÅY4 is 250Å, and the total thickness is 1250Å. Additionally, A(X1+X2) is 750 Å, and B(Y1+Y2+Y3+Y4) is 500 Å, so there is a condition of A>B.

In Comparative Example 2, X1 is 50ÅX2 is 600ÅY1 is 100ÅY2 is 100ÅY3 is 50ÅY4 is 350Å, and the total thickness is 1250Å. In addition, A (X1 +

In Comparative Example 3, X1 is 50ÅX2, 600ÅY1, 50ÅY2, 50ÅY3, 50ÅY4 is 450Å, and the total thickness (Total) is 1250Å. In addition, A (X1 +

In Example 1, X1 is 50ÅX2, 400ÅY1 is 100ÅY2, 100ÅY3 is 50ÅY4 is 450Å, and the total thickness is 1150Å. Additionally, A(X1+X2) is 450 Å, and B(Y1+Y2+Y3+Y4) is 700 Å, so there is a condition of A<B.

Referring to FIG. 3, the driving voltage (Volt) and current efficiency (Cd/A) for each red (R), green (G), and blue (B) sub-pixel region for Comparative Examples 1, 2, and 3 and Example 1 ), the characteristics of color coordinates (CIE_x, CIE_y) were analyzed.

Looking at the characteristics of Comparative Examples 1, 2, 3 and Example 1, A (X1 + It can be seen that Example 1 exhibits lower power consumption (12.3W) and higher luminance (brightness) than the comparative examples.

In particular, the power supply voltage (Vdd) is almost the same as Comparative Example 1, but it can be seen that power consumption and panel brightness characteristics are excellent.

That is, in the present invention, it can be seen that high light efficiency is achieved with low power consumption by controlling the thickness of the organic material between the organic light-emitting layers and the thickness of the organic material disposed below the organic light-emitting layer.

In addition, as shown in FIG. 4, looking at the lifespan of the organic light emitting diodes arranged in the red (R), green (G), and blue (B) sub-pixel areas, the device lifespan of Example 1 (which showed low power consumption) You can see that LifeTime) appears the longest.

In Comparative Examples 1 to 3, the lifespan of the organic light emitting diode is about half that of Example 1, which is because the lifespan of the device is reduced due to high temperature operation due to high power consumption.

In the present invention, the thickness of the organic material layers between the first organic light-emitting layer 135 and the second organic light-emitting layer 235 is formed to be thicker than the thickness of the organic material layers between the first electrode 110 and the first organic light-emitting layer 135, thereby improving light efficiency. did.

The organic electroluminescent display device having a micro-cavity structure of the present invention arranges two or more light-emitting layers in red (R), green (G), and blue (B) sub-pixel areas, and adjusts the distance between the light-emitting layers. It has the effect of improving light efficiency.

In addition, the organic electroluminescent display device having a micro-cavity structure of the present invention has two or more light-emitting layers arranged in red (R), green (G), and blue (B) sub-pixel areas, and disposed above and below the light-emitting layers. There is an effect of improving the efficiency of white light of the display panel by adjusting the thickness of the organic material layers.

FIG. 5 is a table of thickness values of other embodiments of the present invention and comparative examples, FIG. 6 is a diagram comparing light efficiency characteristics in the blue (B) pixel area for other embodiments of the present invention, and FIG. 7 is a diagram comparing the luminous efficiency characteristics in the green (B) pixel area for different embodiments of the present invention, and Figure 8 is a diagram comparing the luminous efficiency characteristics in the red (R) pixel area for other embodiments of the present invention. It is a drawing.

Referring to Figures 5 to 8 along with Figure 1, in the organic electroluminescent display device according to another embodiment of the present invention, the hole injection layer 120 and the first hole disposed below the first organic light emitting layer 135. The thickness of the transport layer 130 is A(X1+X2), the thickness of the first electron transport layer 136 and the first charge generation layer 151 is C(Y1+Y2), and the second charge generation layer ( 152) and the thickness of the second hole transport layer 230 is D(Y3+Y4), and the thickness of the second electron transport layer 240 is E.

[Equation 2]

D≥A (D is Y3+Y4, A is X1+X2)

[Equation 3]

D+E≥A+C (A is X1+X2, C is Y1+Y2, D is Y3+Y4, E)

[Equation 4]

(D+E)/(A+C)≥1 (A is X1+X2, C is Y1+Y2, D is Y3+Y4, E)

Here, A is the thickness of the hole injection layer 120 (X1) and the thickness (X2) of the first hole transport layer 130, and D is the thickness (Y4) of the second hole transport layer 230, or 2 The thickness may be the sum of the thickness (Y4) of the hole transport layer 230 and the thickness (Y3) of the second charge generation layer 152.

In addition, C may be the thickness (Y1) of the first electron transport layer 136, or the combined thickness of the thickness (Y1) of the first electron transport layer 136 and the thickness (Y2) of the first charge generation layer 151. .

As explained in FIG. 1, since the first charge generation layer 151 and the second charge generation layer 152 can be selectively formed or removed, the thickness of the organic material layers of D and C depends on the presence or absence of the charge generation layer. can be changed.

If the above conditions are satisfied, the red light, green light, and blue light generated from the first organic light emitting layer 135 corresponding to the red (R), green (G), and blue (B) sub-pixel regions are transmitted to the second organic light emitting layer. After the red light, green light, and blue light generated at 235 are reflected by the first electrode 110, constructive interference occurs without destructive interference, thereby maximizing optical efficiency.

In other words, if a micro cavity structure is implemented to meet the conditions of Equations 2 to 4 in the red (R), green (G), and blue (B) sub-pixel areas, the extraction efficiency of red light, green light, and blue light generated respectively can be reduced. By increasing it to the maximum, the white light efficiency of the display panel can be improved.

Specific examples of the organic electroluminescent display device of the present invention are as follows.

Referring to Figures 5 to 8, in Comparative Example 4, the thickness of A was set to 400Å, the thickness of C was set to 300Å, the thickness of D was set to 300Å, and the thickness of C was set to 300Å to meet the condition of A+C>D+E. Comparative Example 4 corresponds to a mathematical equation opposite to the light efficiency improvement structure of the present invention.

In Example 2, the thickness of A was set to 350ÅC, the thickness of 300ÅD, and the thickness of 350ÅE were set to 300Å to meet the conditions of A+C=D+E.

In Example 3, the thickness of A was set to 350 ÅC, the thickness of A to 200 ÅD, the thickness of 450 ÅE, and the thickness of A to 300 Å to meet the conditions of A + C < D + E.

In Example 4, the thickness of A was set to 300 ÅC, the thickness of 200 ÅD, and the thickness of 500 ÅE were set to 300 Å to meet the conditions of A + C < D + E.

In Example 4, the thickness condition of D+E was made larger than that in Example 3.

Looking at the device characteristics in the blue (B) sub-pixel area of FIG. 6, it can be seen that both current efficiency [cd/A] and external quantum efficiency [EQE] are improved from Comparative Example 4 to Example 4. On the other hand, it can be seen that the change in color coordinate value and driving voltage is not large, and by applying the design structure of the present invention, it can be seen that the luminous efficiency of blue light can be improved with a voltage that is almost the same as the conventional driving voltage.

Looking at the device characteristics in the green (G) sub-pixel area of FIG. 7, it can be seen that the current efficiency [cd/A] and external quantum efficiency [EQE] were improved in Examples 3 and 4 compared to Comparative Example 4 and Example 2. You can. On the other hand, it can be seen that the change in color coordinate value and driving voltage is not large, and by applying the design structure of the present invention, it can be seen that the luminous efficiency of green light can be improved with almost the same voltage as the conventional driving voltage.

Looking at the device characteristics in the red (R) sub-pixel area of FIG. 8, Examples 3 and 4 have slightly lower current efficiency [cd/A] than Comparative Example 4 and Example 2 in the red (R) sub-pixel area. , it can be seen that there is no significant change in external quantum efficiency [EQE].

On the other hand, it can be seen that the changes in color coordinate values and driving voltage are not large.

When the design structure of the present invention is applied, high luminous efficiency does not appear in the red (R) sub-pixel area, but high luminous efficiency appears in the blue (B) and green (G) sub-pixel areas, thereby reducing the white (W) color of the display panel. Light efficiency is improved.

In particular, since white (W) light efficiency greatly depends on blue (B) light efficiency, improving the efficiency of blue (B) light improves the white light efficiency of the display panel.

The organic light emitting display device according to the present invention stacks two or more organic light emitting diodes in red (R), green (G), and blue (B) sub-pixel areas, and the distance between the light emitting layers of the organic light emitting diodes is, There is an effect of improving light efficiency by adjusting the distance between the light emitting layer and the electrode of the organic light emitting diode.

In addition, the organic electroluminescent display device according to the present invention has an electron transport layer (ETL) and a hole transport layer (HTL) of organic light emitting diodes stacked in the red (R), green (G), and blue (B) sub-pixel regions, respectively. By adjusting the thickness, there is an effect of reducing power consumption.

110: first electrode 120: hole injection layer
130: first hole transport layer 135: first organic light-emitting layer
136: first electron transport layer 140: second electrode
150: capping layer 230: second hole transport layer
235: second organic light-emitting layer 240: second electron transport layer

Claims (24)

A substrate including sub-pixels divided into red (R), green (G), and blue (B) colors;
a first electrode disposed on the sub-pixel;
a plurality of first light emitting units including a first organic light emitting layer and disposed on the first electrode;
a first charge generation layer disposed on the first light emitting unit;
a second charge generation layer disposed on the first charge generation layer;
a plurality of second light-emitting units including a second organic light-emitting layer and disposed on the second charge generation layer; and
a second electrode disposed on the second light emitting unit; Including,
A display device wherein the distance between the first charge generation layer and the second organic light-emitting layer is greater than the distance between the first electrode and the first organic light-emitting layer. The display device of claim 1, wherein the first electrode has the same thickness in the red (R), green (G), and blue (B) sub-pixels. According to paragraph 1,
The first light-emitting unit and the second light-emitting unit arranged to correspond to the red (R), green (G), and blue (B) sub-pixels, respectively, emit light in the same color. The display device according to claim 1, wherein the thickness of the first organic emission layer and the thickness of the second organic emission layer are different from each other. The method of claim 1, wherein the first light emitting unit further includes a hole injection layer and a first hole transport layer,
The display device wherein the second light emitting unit further includes a second hole transport layer. The method of claim 5, wherein the hole injection layer and the first hole transport layer are disposed between the first electrode and the first organic light-emitting layer,
A display device, wherein the second hole transport layer is disposed between the second charge generation layer and the second organic light emitting layer. The display device of claim 5, wherein the sum of thicknesses (D) of the second charge generation layer and the second hole transport layer is greater than the sum of thicknesses (A) of the hole injection layer and the first hole transport layer. . The method of claim 5, wherein the first light emitting unit further includes a first electron transport layer,
The display device wherein the second light emitting unit further includes a second electron transport layer. The method of claim 8, wherein the sum of the thicknesses of the second charge generation layer and the second hole transport layer (D) is greater than the sum of the thicknesses of the first electron transport layer and the first charge generation layer (C). Display device. The method of claim 8, wherein the sum (A+C) of the thicknesses of the hole injection layer, the first hole transport layer, the first electron transport layer, and the first charge generation layer is the second charge generation layer, the second hole A display device characterized in that it is smaller than the sum (D+E) of the thicknesses of the transport layer and the second electron transport layer. The method of claim 8, wherein the thickness (B) of the organic material layer between the first organic light-emitting layer and the second organic light-emitting layer is greater than the thickness (A) of the organic material layer between the first electrode and the first organic light-emitting layer. Display device. The method of claim 11, wherein the thickness (B) of the organic material layer between the first organic emission layer and the second organic emission layer is the first electron transport layer, the first charge generation layer, the second charge generation layer, and the second hole transport layer. A display device characterized in that the thickness is the sum of the thicknesses. The display device of claim 11, wherein the thickness (A) of the organic material layer between the first electrode and the first organic light-emitting layer is the sum of the thicknesses of the hole injection layer and the first hole transport layer. The display device of claim 5, wherein the hole injection layer is a common layer of the red (R), green (G), and blue (B) sub-pixel regions. The display device of claim 1, wherein the first charge generation layer and the second charge generation layer have an NP junction structure. The method of claim 1, wherein the first organic light-emitting layer includes a red light-emitting layer, a green light-emitting layer, and a blue light-emitting layer, corresponding to the red (R), green (G), and blue (B) sub-pixel regions, respectively, and , A display device characterized in that the green and blue light emitting layers have different thicknesses. The method of claim 1, wherein the second organic light emitting layer includes a red light emitting layer, a green light emitting layer, and a blue light emitting layer, respectively corresponding to the red (R), green (G), and blue (B) sub-pixel regions, and the red light emitting layer and the blue light emitting layer. , A display device characterized in that the green and blue light emitting layers have different thicknesses. The display device according to claim 1, wherein the first electrode has a stacked structure of a first metal film having a high reflectivity and a second metal film formed of a transparent conductive material on the first metal film. The display device of claim 18, wherein the first metal film is aluminum (Al) or silver (Ag), and the second metal film is indium tin oxide (ITO) or indium zinc oxide (IZO). The method of claim 1, wherein the second electrode is a single layer composed of silver (Ag), aluminum (Al), magnesium (Mg), lithium (Li), calcium (Ca), lithium fluoride (LiF), ITO, and IZO. A display device characterized by a multi-layer structure. The display device of claim 1, wherein the red (R), green (G), and blue (B) sub-pixel areas are divided in a horizontal direction. The display device of claim 1, wherein the red (R), green (G), and blue (B) sub-pixel areas emit white light. The display device of claim 1, wherein the red (R) sub-pixel area, the green (G) sub-pixel area, and the blue (B) sub-pixel area have different heights. The display device of claim 23, wherein the red (R) sub-pixel area has the highest height and the blue (B) sub-pixel area has the lowest height.