KR20140086803A - Organic light emitting display and method of fabricating the same - Google Patents

Abstract

The present invention provides an organic light emitting display device and a method of fabricating the same having extended life span and improved efficiency. According to the present invention, the organic light emitting display device includes: a first and second electrodes facing each other on a substrate; an electric charge generating layer formed between the first electrode and the second electrode; a first light emitting unit having a first light emitting layer formed between the first electrode and the electric charge generating layer, a hole transport layer to supply a hole from the first electrode to the first light emitting layer, and a first electron transport layer to supply an electron from the electric charge generating layer to the first light emitting layer; and a second light emitting unit having a second light emitting layer formed between the second electrode and the electric charge generating layer, a hole transport layer to supply a hole from the electric charge generating layer to the second light emitting layer, and a second electron transport layer to supply an electron from the second electrode to the second light emitting layer. The entire thickness of the hole transport layer of the first light emitting unit is greater than the entire thickness of the hole transport layer of the second light emitting unit.

Description

TECHNICAL FIELD [0001] The present invention relates to an organic light emitting diode (OLED) display device,

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an organic light emitting display device and a manufacturing method thereof, which can improve lifetime and efficiency.

Recently, as the information age has come to the information age, a display field for visually expressing electrical information signals has been rapidly developed. In response to this, a variety of flat display devices having excellent performance such as thinning, light weight, and low power consumption have been developed. Device) is being developed.

Specific examples of such flat panel display devices include a liquid crystal display device (LCD), a plasma display panel (PDP), a field emission display (FED) (Organic Light Emitting Device: OLED).

Particularly, the organic light emitting display device is advantageous in that it has a higher response speed and a larger light emitting efficiency, luminance, and viewing angle than other flat panel display devices.

However, the organic light emitting display device has a short life span and low efficiency as compared with other flat panel display devices. Therefore, recently, a method for improving the lifetime and efficiency of the organic light emitting display device has been demanded.

In order to solve the above problems, the present invention provides an organic light emitting display and a method of manufacturing the same, which can improve lifetime and efficiency.

According to an aspect of the present invention, there is provided an organic light emitting diode display comprising: first and second electrodes opposing each other on a substrate; A charge generation layer formed between the first and second electrodes; A first light emitting layer formed between the first electrode and the charge generating layer, a hole transporting layer supplying holes from the first electrode to the first light emitting layer, a second light emitting layer supplying electrons from the charge generating layer to the first light emitting layer, A first light emitting unit having one electron transporting layer; A second light emitting layer formed between the second electrode and the charge generating layer, a hole transporting layer supplying holes from the charge generating layer to the second light emitting layer, and a second light emitting layer supplying electrons from the second electrode to the second light emitting layer And a second light emitting unit having a second electron transporting layer, wherein the total thickness of the hole transporting layer of the first light emitting unit is thicker than the total thickness of the hole transporting layer of the second light emitting unit.

Wherein the hole transport layer of the first light emitting unit comprises a first hole transport layer and a second hole transport layer that is thicker than the first hole transport layer, the hole transport layer of the second light emission unit comprises a third hole transport layer, And the sum of the thicknesses of the first and second hole transporting layers is greater than the sum of the thicknesses of the third and fourth hole transporting layers.

And the thickness of the first hole transporting layer is larger than the thickness of the third hole transporting layer.

The first hole transport layer is formed to a thickness of 700 to 1200 ANGSTROM, the second hole transport layer is formed to a thickness of 150 ANGSTROM to 250 ANGSTROM, the third hole transport layer is formed to a thickness of 250 ANGSTROM to 350 ANGSTROM, Is formed to a thickness of 100 to 150 ANGSTROM.

The hole mobility of the first hole transport layer is faster than the hole mobility of the second hole transport layer and the hole mobility of the third hole transport layer is faster than the hole mobility of the fourth hole transport layer.

And the hole mobility of the first hole transport layer is higher than the hole mobility of the third hole transport layer.

Wherein the organic light emitting display comprises: a second charge generating layer formed on a second electron transporting layer of the second light emitting unit; And a third light emitting unit formed between the second charge generation layer and the second electrode, wherein the third light emitting unit includes a third light emitting layer formed between the second electrode and the second charge generating layer, And a third light emitting unit having a hole transporting layer for supplying holes from the second charge generating layer to the third light emitting layer and a third electron transporting layer for supplying electrons to the third light emitting layer, The total thickness of the transport layer is thicker than the total thickness of the hole transport layer of the third light emitting unit and the thickness of the hole transport layer of the third light emitting unit is thicker than the thickness of the hole transport layer of the second light emitting unit.

The thickness of the hole transporting layer of the first light emitting unit is more than about 1050 Å and less than 1450 Å. The thickness of the hole transporting layer of the second light emitting unit is 200 to 600 Å. The thickness of the hole transporting layer of the third light emitting unit is 800 to 1000 ANGSTROM.

The two light emitting layers of the first to third light emitting layers implement a blue color, and the remaining light emitting layers realize a green color.

According to an aspect of the present invention, there is provided a method of manufacturing an organic light emitting diode display, including: forming a first electrode on a substrate; Forming a first light emitting unit having a first light emitting layer on the first electrode, a hole transporting layer supplying holes from the first electrode to the first light emitting layer, and a first electron transporting layer supplying electrons to the first light emitting layer ; Forming a charge generation layer for supplying the electrons to the first electron transport layer on the first light emitting unit; Forming a second light emitting unit having a second light emitting layer on the charge generating layer, a hole transporting layer for supplying holes from the charge generating layer to the second light emitting layer, and a second electron transporting layer for supplying electrons to the second light emitting layer ; And forming a second electrode on the second light emitting unit to supply the electrons to the second electron transporting layer, wherein a total thickness of the hole transporting layer of the first light emitting unit is larger than a total thickness of the hole transporting layer of the second light emitting unit And is thicker than the entire thickness.

The method of fabricating an organic light emitting display device includes forming a second charge generating layer on the second light emitting unit to supply electrons to the second electron transporting layer; A third light emitting layer having a third light emitting layer on the second charge generating layer, a hole transporting layer supplying holes from the second charge generating layer to the third light emitting layer, and a third electron transporting layer supplying electrons to the third light emitting layer Wherein the thickness of the hole transporting layer of the first light emitting unit is thicker than the thickness of the hole transporting layer of the third light emitting unit and the thickness of the hole transporting layer of the third light emitting unit is greater than the thickness of the second light emitting unit Is thicker than the thickness of the hole transport layer of the unit.

The thickness of the hole transport layer included in each of the plurality of light emitting units is differently formed. Accordingly, the organic light emitting display device and the method of manufacturing the same according to the present invention have improved efficiency and lifetime, and improved viewing angle.

1 is a cross-sectional view illustrating an organic light emitting display according to a first embodiment of the present invention.
2 is a diagram showing a band diagram of the organic light emitting display shown in FIG.
3 is a flowchart illustrating a method of manufacturing an organic light emitting diode display according to a first embodiment of the present invention.
4 is a cross-sectional view illustrating an OLED display according to a second embodiment of the present invention.
FIG. 5 is a diagram illustrating a band diagram of the organic light emitting display shown in FIG.
FIG. 6 is a graph showing the light emission intensities of green and blue light generated in the first to third light emitting layers shown in FIGS. 4 and 5. FIG.
FIGS. 7A and 7B are diagrams for explaining the emission peak of the organic light emitting display shown in FIG.
8 is a flowchart illustrating a method of manufacturing an OLED display according to a second embodiment of the present invention.
9 is a cross-sectional view illustrating an OLED display device having color filters according to first and second embodiments of the present invention.

Hereinafter, exemplary embodiments of the present invention will be described in detail with reference to the accompanying drawings and embodiments.

FIG. 1 is a cross-sectional view illustrating an organic light emitting display according to a first embodiment of the present invention, and FIG. 2 is a band diagram of the organic light emitting display shown in FIG.

The organic light emitting display shown in FIGS. 1 and 2 includes first and second electrodes 102 and 104 facing each other, first and second light emitting units 110 and 120 formed between the first and second electrodes 102 and 104, And a charge generation layer 130 located between the first and second light emitting units 110 and 120. In the present invention, the case where two light emitting units are used has been described as an example, but the light emitting units may be formed further.

At least one of the first and second electrodes 102 and 104 is formed as a transflective electrode and the other of the first and second electrodes 102 and 104 is formed as a reflective electrode. When the first electrode 102 is a transflective electrode and the second electrode 104 is a reflective electrode, the light is emitted to the bottom. When the second electrode 104 is a transflective electrode and the first electrode 102 is a reflective electrode, it is a top emission structure that emits light to the top. In the present invention, the first electrode 102 is formed as a reflective electrode as an anode, and the second electrode 104 is formed as a transflective electrode as a cathode.

The first electrode 102 is formed in a multilayer structure including a metal layer made of aluminum (Al) or an aluminum alloy (AlNd) and a transparent layer made of indium tin oxide (ITO) or indium zinc oxide And serves as a reflective electrode.

The second electrode 104 may be a single layer or a multilayer, and each layer constituting the second electrode 104 may be formed of a metal, an inorganic material, a metal mixed layer, or a mixed metal or inorganic material or a mixture thereof. At this time, when each layer is a mixed layer of metal and inorganic, the ratio is 10: 1 to 1:10, and when each layer is a mixed layer of metal and metal, the ratio is 10: 1 to 1:10 . The metal forming the second electrode 104 is formed of Ag, Mg, Yb, Li, or Ca, and the inorganic material is formed of Li ₂ O, CaO, LiF, or MgF ₂ , We can supply a lot.

The charge generation layer 130 generates and separates electrons as an n-type charge and holes as a p-type charge. The charge generation layer is formed on the N-type charge generation layer 130a formed on the first electron transport layer 118 of the first light emitting unit 110 and on the third hole transport layer 124a And a P-type charge generating layer 130b formed under the charge generating layer 130b. The N-type charge generation layer 130a injects electrons into the first light emitting unit 110 and holes injected from the first electrode 102 are injected into the first light emitting layer 116 of the first light emitting unit 110, To form excitons and emit light in the visible light region while emitting energy. The P-type charge generation layer 130b is formed by injecting holes into the second light emitting unit 120 and electrons moved from the second electrode 104 by the second light emitting layer 126 to form excitons, And emits light in the visible light region.

Here, the first light emitting layer 116 emits blue light to the light emitting layer including the blue fluorescent dopant and the host, the second light emitting layer 126 emits orange light to the light emitting layer including the yellow-green phosphorescent dopant and the host, Can be implemented. In addition, other fluorescent dopants and phosphorescent dopants can be used to realize white light.

The first light emitting unit 110 is formed between the first electrode 102 and the charge generating layer 130. The first light emitting unit 110 includes a hole injection layer 112 sequentially formed on the first electrode 102, first and second hole transporting layers 114a and 114b, a first light emitting layer 116, And a transport layer 118. The first and second hole transporting layers 114a and 114b supply holes from the first electrode 102 to the first emitting layer 116 and the first electron transporting layer 118 supplies electrons from the charge generating layer 132 The holes supplied through the first and second hole transporting layers 114 and the electrons supplied through the first electron transporting layer 118 are recombined in the first light emitting layer 116, Is generated.

Particularly, the first hole transport layer 114a supplies holes from the first electrode 102 to the second hole transport layer 114b and controls the cavity of the blue light generated in the first light emitting unit 110. The first hole transport layer (114a) is the amount of change in hole mobility ^{(5.0 × 10 -3 Vs / cm} 2) in accordance with the thickness is formed of a material small. For example, the first hole transport layer 114a is formed of at least one of rubrene, NPB, TBP, TAPC, TCTA, and 2-TMATA. At this time, the first hole transport layer 114a is formed to a thickness of about 700 to 1200 ANGSTROM.

The second hole transport layer 114b supplies holes from the first hole transport layer 114a to the first emission layer 116 and controls the cavity of the blue light generated by the first emission unit 110. [ The second hole transport layer 114b serves to block electrons supplied to the first emission layer 116. [ Here, the second hole transport layer 114b is formed of a material whose hole mobility is slower than that of the first hole transport layer 114a, so that electrons supplied to the first emission layer 116 are not transferred to the other layer, ) To block electrons to be coupled with electrons. For example, the second hole transport layer 114b may be formed of at least one of rubrene, NPB, TBP, TAPC, TCTA, and 2-TMATA.

On the other hand, since the mobility of the second hole transport layer 114b is lower than that of the first hole transport layer 114a, if the thickness of the second hole transport layer 114b increases, the driving voltage increases and the lifetime decreases do. Accordingly, the second hole transport layer 114b is formed to a thickness of about 150 to 250 ANGSTROM thinner than the first hole transport layer 114A.

The second light emitting unit 120 is formed between the second electrode 104 and the charge generating layer 130. The second light emitting unit 120 includes third and fourth hole transporting layers 124a and 124b, a second light emitting layer 126, and a second electron transporting layer 128 sequentially formed on the charge generating layer 130 . The third and fourth hole transporting layers 124a and 124b supply holes from the charge generating layer 1342 to the second light emitting layer 126 and the second electron transporting layer 128 supplies electrons from the second electrode 132 The holes supplied through the third and fourth hole transporting layers 124 and the electrons supplied through the second electron transporting layer 128 are recombined in the second light emitting layer 126, Is generated.

The third hole transport layer 124a supplies holes from the charge generation layer 130 to the fourth hole transport layer 124b and controls the cavity of the orange light generated in the second light emitting unit 120. [ The third hole transporting layer 124a is formed of a material having a higher hole mobility than the first and second hole transporting layers because holes injected from the charge generating layer 130 are injected. For example, the third hole transport layer 124a is formed of at least one of rubrene, NPB, TBP, TAPC, TCTA, and 2-TMATA. At this time, the third hole transport layer 124a is formed to a thickness of about 250 to 350 ANGSTROM.

The fourth hole transport layer 124b supplies holes from the third hole transport layer 124a to the second light emitting layer 126 and controls the cavity of the orange light generated in the second light emitting unit 120. [ Further, the fourth hole transport layer 124b is formed to have a triplet energy level (T1, for example, 2.5) of the second light emitting layer 126 so as to block electrons supplied to the second light emitting layer 126 And has a high triplet energy level (T1).

Here, the fourth hole transport layer 124b is formed of a material whose hole mobility is slower than that of the third hole transport layer 124a. For example, the fourth hole transport layer 124b is formed of at least one of rubrene, NPB, TBP, TAPC, TCTA, and 2-TMATA. On the other hand, since the mobility of the fourth hole transport layer 124b is slower than that of the third hole transport layer 124a, if the thickness of the fourth hole transport layer 124b increases, the driving voltage increases and the lifetime decreases do. Accordingly, the fourth hole transporting layer 124b is formed to a thickness of about 100 to 150 ANGSTROM thinner than the third hole transporting layer 124a.

The organic light emitting display according to the first embodiment of the present invention is formed such that the thicknesses of the first through fourth hole transporting layers 114a, 114b, 124a, and 124b satisfy Equation (1).

T3 is the thickness of the third hole transporting layer 124a, T4 is the thickness of the fourth hole transporting layer 124a, and T4 is the thickness of the third hole transporting layer 124a. In the equation 1, T1 is the thickness of the first hole transporting layer 114a, T2 is the thickness of the second hole transporting layer 114b, TT1 denotes the sum of the thicknesses of the first and second hole transporting layers 114a and 114b, that is, the total thickness of the hole transporting layer of the first light emitting unit 110, and TT2 denotes the thicknesses of the third and fourth hole transporting layers 114a and 114b. (124a, 124b), i.e., the total thickness of the hole transporting layer of the second light emitting unit 120.

When the condition of Equation (1) is satisfied, the blue light generated by the first light emitting unit 110 and the orange light generated by the second light emitting unit 120 can generate constructive interference to optimize the luminous efficiency, .

Table 1 shows voltage (V), chromaticity coordinates (CIE_x, CIE_y) and efficiency (cd / A) measured according to the thicknesses of the first and second hole transporting layers 114a and 114b, 2 shows the voltage (V), the color coordinates (CIE_x, CIE_y), and the efficiency (cd / A) measured in the structure of the comparative example and the embodiment according to the thicknesses of the third and fourth hole transporting layers 124a and 124b. In Table 1 and Table 2, HTL1, HTL2, HTL3 and HTL4 represent the first through fourth hole transporting layers 114a, 114b, 124a and 124b, respectively.

rescue HTL1 [Å] HTL2 [Å] HTL3 [Å] HTL4 [Å] V CIE_x CIE_y cd / ACIE_xCIE_ycd / A Comparative Example 1350 0 300







150







7.5 0.305 0.319 50 Comparative Example 1300 50 7.5 0.307 0.321 68 Example 1200 150 7.5 0.306 0.322 75 Example 1000 350 7.8 0.309 0.32 76 Example 800 550 8.5 0.31 0.321 77 Comparative Example 600 750 10 0.311 0.329 76 Comparative Example 400 950 12 0.309 0.328 71 Comparative Example 200 1150 12 0.307 0.325 69 Comparative Example 0 1350 12 0.305 0.32 70

rescue HTL1 [Å] HTL2 [Å] HTL3 [Å] HTL4 [Å] V CIE_x CIE_y cd / ACIE_xCIE_ycd / A Comparative Example 1200








150








450 0 7.5 0.311 0.319 65 Comparative Example 400 50 7.5 0.308 0.322 68 Comparative Example 350 100 7.5 0.309 0.329 72 Example 300 150 7.5 0.306 0.322 75 Comparative Example 250 200 7.7 0.308 0.33 76 Comparative Example 200 250 7.9 0.311 0.331 77 Comparative Example 150 300 8 0.301 0.325 77 Comparative Example 100 350 10 0.311 0.326 77 Comparative Example 50 400 10 0.315 0.327 70 Comparative Example 0 450 10 0.312 0.33 70

As shown in Table 1, the driving voltage increases as the thickness of the first hole transport layer 114a decreases and the thickness of the second hole transport layer 114b increases. As shown in Table 2, the third hole transport layer 124a, And the driving voltage increases as the thickness of the fourth hole transport layer 124b increases. Accordingly, as shown in Tables 1 and 2, the first hole transport layer 114a has a thickness of about 700 to 1200 ANGSTROM and the second hole transport layer 114b has a thickness of about 150 ANGSTROM to 250 ANGSTROM thinner than the first hole transport layer 114A. The third hole transport layer 124a is formed to a thickness of about 250 to 350 ANGSTROM and the fourth hole transport layer 124b is formed to a thickness of about 100 ANGSTROM to 150 ANGSTROM thinner than the third hole transport layer 124A, It can be seen that the electro-optical characteristics such as the voltage (V), the color coordinates (CIE_x, CIE_y) and the efficiency (cd / A) are improved. Also, in the embodiment of the present invention, if the efficiency is increased as described above, the driving current is reduced, and the same brightness as the conventional one can be obtained with a relatively low current. Accordingly, the lifetime of the organic light emitting diode display according to the present invention is also improved.

3 is a flowchart illustrating a method of manufacturing an organic light emitting diode display according to a first embodiment of the present invention.

First, a first electrode 102 is formed on a substrate 101 (step S10). The hole injection layer 112, the first and second hole transporting layers 114a and 114b, the first light emitting layer 116 and the first electron transporting layer 118 are formed on the substrate 101 on which the first electrode 122 is formed. A deposition method, a sputtering method, or a combination thereof, so that the first light emitting unit 110 is formed (step S12). Then, the charge generating layer 130 is formed on the first light emitting unit (step S14). The third and fourth hole transporting layers 124a and 124b, the second light emitting layer 126 and the second electron transporting layer 128 are formed on the substrate 101 on which the charge generating layer 130 is formed by a thermal deposition method, a sputtering method, And the second light emitting unit 120 is formed by sequentially stacking them in accordance with the combination method (step S16). The second electrode 104 is formed on the substrate 101 on which the second light emitting unit 120 is formed (step S18).

FIG. 4 is a block diagram illustrating an organic light emitting display according to a second embodiment of the present invention, and FIG. 5 is a band diagram illustrating the organic light emitting display shown in FIG.

The organic light emitting display shown in FIGS. 4 and 5 is different from the organic light emitting display shown in FIG. 1 in that a second charge generating layer (first charge generating layer) 132 composed of an N type charge generating layer 132a and a P type charge generating layer 132b 132, and a third light emitting unit 140 are additionally provided. Accordingly, detailed description of the same constituent elements will be omitted.

That is, the organic light emitting display shown in FIG. 4 includes first and second electrodes 102 and 104 facing each other; A first charge generation layer 130 formed between the first and second light emitting units 110 and 120, and a second charge generation layer 130 formed between the first and second light emitting units 110 and 120. The first and third light emitting units 110 and 120, And a second charge generating layer 132 formed between the first and second light emitting units 120 and 140.

The first light emitting unit 110 includes a hole injecting layer 112, a first hole transporting layer 214, a first light emitting layer 116 for emitting blue light, and a second electron transporting layer 112 sequentially formed on the first electrode 102. [ And a transport layer 118. In particular, the first hole transport layer 214 supplies holes from the first electrode 102 to the first emission layer 116 and controls the cavity of the blue light generated by the first emission unit 110.

The second light emitting unit 120 is formed between the first and third light emitting units 110 and 140. The second light emitting unit 120 includes a second hole transporting layer 224 sequentially formed on the first charge generating layer 130 located on the first light emitting unit 110, a second light emitting layer 126 ), And a second electron transporting layer (128). Particularly, the second hole transport layer 224 supplies holes from the first charge generation layer 130 to the second emission layer 126 and controls the cavity of the green light generated in the second emission unit 120 do.

The third light emitting unit 140 is formed between the second charge generating layer 132 and the second electrode 104. The third light emitting unit 140 includes a third hole transporting layer 244 sequentially formed on the second charge generating layer 132, a third light emitting layer 146 emitting blue light, and a third electron transporting layer 148 Respectively. Particularly, the third hole transport layer 244 supplies holes from the second charge generation layer 132 to the third emission layer 146 and controls the cavity of the blue light generated in the third emission unit 140 do.

Specifically, the blue light generated by the first and third light emitting units 110 and 140 is repeatedly refracted and reflected within the resonance region between the first and second electrodes 102 and 104. That is, due to the micro-cavity effect in which the blue light generated in each of the first and third light emitting layers 116 and 146 and the blue light reflected from the first electrode 102 interfere constructively, the resonance between the first and second electrodes 102 and 104 A blue light emission intensity (BEI) characteristic as shown in Fig. 6 appears in the region. The blue light emission intensity (BEI) has a plurality of blue emission peaks in the resonance region between the first and second electrodes 102 and 104.

Further, the green light generated by the second light emitting unit 120 is repeatedly refracted and reflected within the resonance region between the first and second electrodes 102 and 104. That is, even in the resonance region between the first and second electrodes 102 and 104, due to the micro-cavity effect in which the green light generated in the second emission layer 26 and the green light reflected in the first electrode 102 interfere constructively, (GEI) as shown in Fig. At this time, since the green light has a peak wavelength longer than that of the blue light, the green light emission intensity GEI has a plurality of green light emission peaks less than the blue light emission intensity BEI in the resonance region between the first and second electrodes 102 and 104.

At this time, when the blue light emitting layer 116 and the green light emitting layer 126 are positioned at the green light emitting peak position at the blue light emitting peak position, the highest light emitting efficiency can be obtained.

The positions of the hole injection layer 112 located under the first light emitting layer 116 and the first light emitting layer 116 for generating blue light by adjusting the thickness of the first hole transporting layer 214 are determined. The distance d1 from the upper surface of the first electrode 102 to the lower surface of the first light emitting layer 116, that is, the distance between the hole injection layer 112 located under the first light emitting layer 116, And the sum of the thicknesses of the hole transporting layer 214 is 1200 to 1400 ANGSTROM.

The thickness of the electron transport layer 118, the first charge generation layer 130 and the second hole transport layer 224 located between the first and second emission layers 116 and 126 is controlled to form a second light emission layer 126 are determined. The distance d2 from the upper surface of the first light emitting layer 116 to the lower surface of the second light emitting layer 126, that is, the electron transporting layer 118 located between the first and second light emitting layers 116 and 126, The sum of the thicknesses of the first charge generating layer 130 and the second hole transporting layer 224 is 400 to 600 ANGSTROM.

The thickness of the electron transport layer 128, the second charge generation layer 132, and the third hole transport layer 244 located between the second and third light emitting layers 126 and 146 is adjusted to form a third light emitting layer 146 are determined. The distance d3 from the upper surface of the second light emitting layer 126 to the lower surface of the third light emitting layer 146, that is, the electron transporting layer 128 located between the first and second light emitting layers 116 and 126, The sum of the thicknesses of the second charge generating layer 132 and the third hole transporting layer 244 is set to 1210 to 1350 ANGSTROM.

In particular, when the thicknesses of the electron transporting layers 118, 128, and 148 are adjusted to determine the positions of the first to third light emitting layers 116, 126, and 146, the driving voltage may be increased. Therefore, It is desirable to adjust the thickness of the transport layer 214, 224, 244.

That is, the organic light emitting display according to the present invention is formed such that the thicknesses of the first through third hole transporting layers 214, 224, and 244 satisfy Equation (2).

In the equation (1), TT1 denotes the thickness of the first hole transport layer 214 of the first light emitting unit 110, TT2 denotes the thickness of the second hole transport layer 224 of the second light emitting unit 120, And the thickness of the third hole transport layer 244 of the light emitting unit 140. The thickness of the first hole transport layer 214 is greater than about 1050 Å and less than 1450 Å. The thickness of the second hole transport layer 224 is 200 to 600 Å. The thickness of the third hole transport layer 244 The thickness is formed to 800 to 1000 ANGSTROM.

6, the first emission layer 116 of the first emission unit 110 is located at the second emission peak of the blue emission wavelength BEI, and the second emission layer 116 of the second emission unit 120 126 is located at the second emission peak of the green emission wavelength GEI and the third emission layer 146 of the third emission unit 140 is located at the third emission peak of the blue emission wavelength BEI.

As a result, the blue light generated by the first light emitting unit 110, the green light generated by the second light emitting unit 120, and the blue light generated by the third light emitting unit 140 generate constructive interference, The branch produces white light.

In the second embodiment of the present invention, the first and third light emitting layers 116 and 146 generate blue light and the second light emitting layer 126 generates green light. Alternatively, the first light emitting layer 116 may emit green light The second and third light emitting layers 126 and 146 generate blue light or the first and second light emitting layers 116 and 126 generate blue light and the third light emitting layer 146 generates green light.

The first through third hole transporting layers 214, 224, and 244 are formed at positions where the first through third hole transporting layers 214, 224, and 244 are formed according to the thickness of the first electrode 102 formed on the substrate, The positions of the lower surfaces of the first to third hole transporting layers 214, 224, and 244 may be changed, but the thick order of the thicknesses of the first to third hole transporting layers 214, 224, and 244 is not changed.

Table 3 is for explaining the efficiency characteristics of the organic light emitting display device and the comparative example according to the second embodiment of the present invention.

Example 2
[TT1>TT3> TT2] Comparative Example 1
[TT3>TT1> TT2] Comparative Example 2
[TT1>TT2> TT3] A B C D E F G TT1 [Å] 1150 1250 1350 1050 1450 1250 1250 TT2 [Å] 250 250 250 250 250 650 750 TT3 [Å] 1050 950 850 1150 750 550 450 Efficiency [cd / A] 75 80 74 65 66 30 40

As shown in Table 3 and FIG. 7A, in Comparative Example where the thickness TT1 of the first hole transporting layer of the first light emitting unit 110 is the thickest and the thickness of the hole transporting layer TT3 of the third light emitting unit 140 is the thinnest 1, the emission peak value is lower than that of the organic light emitting display according to the second embodiment of the present invention, resulting in an efficiency reduction efficiency of 30% or more.

Comparative Example 2 in which the thickness TT3 of the hole transporting layer of the third light emitting unit is the thickest and the thickness of the hole transporting layer TT2 of the second light emitting unit 120 is the thinnest is shown in Table 3 and Fig. The peak value is lower than that of the organic light emitting display device according to the second embodiment of the present invention, resulting in an efficiency reduction efficiency of 20% or more.

8 is a flowchart illustrating a method of manufacturing an OLED display according to a second embodiment of the present invention.

First, a first electrode 102 is formed on a substrate 101 (step S20). A hole injection layer 112, a first hole transport layer 214, a first emission layer 116, and a first electron transport layer 118 are formed on a substrate 101 on which a first electrode 122 is formed by a thermal deposition method, a sputtering method Or a combination thereof, so that the first light emitting unit 110 is formed (step S22). Then, the first charge generating layer 130 is formed on the first light emitting unit (step S24). The second hole transporting layer 224, the second light emitting layer 126 and the second electron transporting layer 128 are formed on the substrate 101 on which the first charge generating layer 130 is formed by a thermal deposition method, a sputtering method, And the second light emitting unit 120 is formed sequentially (step S26). Then, a second charge generating layer 132 is formed on the second light emitting unit (step S28). The third hole transporting layer 244, the third emitting layer 146 and the third electron transporting layer 148 are formed on the substrate 101 on which the second charge generating layer 132 is formed by a thermal deposition method, a sputtering method, And the third light emitting unit 140 is formed sequentially (step S30). The second electrode 104 is formed on the substrate 101 on which the third light emitting unit 140 is formed (step S32).

In the second embodiment of the present invention, the hole transporting layers 214, 224 and 244 of the light emitting units 110, 120 and 140 are single-layered. However, as in the first embodiment of the present invention, The transport layers 214, 224, 244 may be multi-layered.

Meanwhile, the OLED display according to the present invention is applicable to a structure having red, green, and blue color filters 150R, 150G, and 150B as shown in FIG. That is, the white light generated through the first and second light emitting units 110 and 120 shown in FIG. 1 or the white light generated through the first through third light emitting units 110, 120, and 140 shown in FIG. The red light is emitted while passing through the sub pixel region in which the blue color filter 150B is formed and the blue light is emitted while passing through the sub pixel region in which the blue color filter 150B is formed , And white light is emitted while passing through the sub pixel region where no color filter is formed.

It will be apparent to those skilled in the art that various modifications and variations can be made in the present invention without departing from the spirit or scope of the invention. Will be clear to those who have knowledge of.

102: first electrode 104: second electrode
110, 120, 140: light emitting unit 116, 126, 146:
130, 132; Charge generation layer

Claims (18)

First and second electrodes facing each other on a substrate;
A charge generation layer formed between the first and second electrodes;
A first light emitting layer formed between the first electrode and the charge generating layer, a hole transporting layer supplying holes from the first electrode to the first light emitting layer, a second light emitting layer supplying electrons from the charge generating layer to the first light emitting layer, A first light emitting unit having one electron transporting layer;
A second light emitting layer formed between the second electrode and the charge generating layer, a hole transporting layer supplying holes from the charge generating layer to the second light emitting layer, and a second light emitting layer supplying electrons from the second electrode to the second light emitting layer And a second light emitting unit having a second electron transporting layer,
Wherein a total thickness of the hole transporting layer of the first light emitting unit is greater than a total thickness of the hole transporting layer of the second light emitting unit. The method according to claim 1,
Wherein the hole transporting layer of the first light emitting unit comprises a first hole transporting layer and a second hole transporting layer thicker than the first hole transporting layer,
The hole transport layer of the second light emitting unit comprises a third hole transport layer and a fourth hole transport layer thicker than the third hole transport layer,
Wherein a sum of thicknesses of the first and second hole transporting layers is greater than a sum of thicknesses of the third and fourth hole transporting layers. 3. The method of claim 2,
Wherein the thickness of the first hole transporting layer is greater than the thickness of the third hole transporting layer. 3. The method of claim 2,
The first hole transport layer is formed to a thickness of 700 to 1200 ANGSTROM,
The second hole transport layer is formed to a thickness of 150 to 250 ANGSTROM,
The third hole transport layer is formed to a thickness of 250 to 350 ANGSTROM,
And the fourth hole transport layer is formed to a thickness of 100 to 150 ANGSTROM. 3. The method of claim 2,
The hole mobility of the first hole transport layer is faster than the hole mobility of the second hole transport layer,
And the hole mobility of the third hole transport layer is higher than the hole mobility of the fourth hole transport layer. 6. The method of claim 5,
And the hole mobility of the first hole transport layer is higher than the hole mobility of the third hole transport layer. The method according to claim 1,
A second charge generation layer formed on the second electron transporting layer of the second light emitting unit;
And a third light emitting unit formed between the second charge generation layer and the second electrode,
The third light emitting unit
A third light emitting layer formed between the second electrode and the second charge generating layer, a hole transporting layer supplying holes from the second charge generating layer to the third light emitting layer, a third hole transporting layer supplying electrons to the third light emitting layer, And a third light emitting unit having an electron transporting layer,
The total thickness of the hole transporting layer of the first light emitting unit is thicker than the total thickness of the hole transporting layer of the third light emitting unit,
Wherein a thickness of the hole transporting layer of the third light emitting unit is thicker than a thickness of the hole transporting layer of the second light emitting unit. 8. The method of claim 7,
The thickness of the hole transporting layer of the first light emitting unit is more than about 1050 Å and less than 1450 Å. The thickness of the hole transporting layer of the second light emitting unit is 200 to 600 Å. The thickness of the hole transporting layer of the third light emitting unit is Wherein the first electrode is formed to a thickness of about 800 to 1000 ANGSTROM. 8. The method of claim 7,
Wherein two of the first to third light emitting layers emit blue light and the remaining light emitting layers emit green light. Forming a first electrode on a substrate;
Forming a first light emitting unit having a first light emitting layer on the first electrode, a hole transporting layer supplying holes from the first electrode to the first light emitting layer, and a first electron transporting layer supplying electrons to the first light emitting layer ;
Forming a charge generation layer for supplying the electrons to the first electron transport layer on the first light emitting unit;
Forming a second light emitting unit having a second light emitting layer on the charge generating layer, a hole transporting layer for supplying holes from the charge generating layer to the second light emitting layer, and a second electron transporting layer for supplying electrons to the second light emitting layer ;
And forming a second electrode for supplying the electrons to the second electron transport layer on the second light emitting unit,
Wherein a total thickness of the hole transporting layer of the first light emitting unit is greater than a total thickness of the hole transporting layer of the second light emitting unit. 11. The method of claim 10,
Wherein the hole transporting layer of the first light emitting unit comprises a first hole transporting layer and a second hole transporting layer thicker than the first hole transporting layer,
The hole transport layer of the second light emitting unit comprises a third hole transport layer and a fourth hole transport layer thicker than the third hole transport layer,
Wherein a sum of thicknesses of the first and second hole transporting layers is greater than a sum of thicknesses of the third and fourth hole transporting layers. 12. The method of claim 11,
Wherein the thickness of the first hole transporting layer is greater than the thickness of the third hole transporting layer. 12. The method of claim 11,
The first hole transport layer is formed to a thickness of 700 to 1200 ANGSTROM,
The second hole transport layer is formed to a thickness of 150 to 250 ANGSTROM,
The third hole transport layer is formed to a thickness of 250 to 350 ANGSTROM,
Wherein the fourth hole transport layer is formed to a thickness of 100 to 150 ANGSTROM. 14. The method of claim 13,
The hole mobility of the first hole transport layer is faster than the hole mobility of the second hole transport layer,
And the hole mobility of the third hole transport layer is higher than the hole mobility of the fourth hole transport layer. 15. The method of claim 14,
Wherein the hole mobility of the first hole transport layer is higher than the hole mobility of the third hole transport layer. 11. The method of claim 10,
Forming a second charge generation layer for supplying the electron to the second electron transport layer on the second light emitting unit;
A third light emitting layer having a third light emitting layer on the second charge generating layer, a hole transporting layer supplying holes from the second charge generating layer to the third light emitting layer, and a third electron transporting layer supplying electrons to the third light emitting layer Further comprising forming a unit,
The thickness of the hole transporting layer of the first light emitting unit is thicker than the thickness of the hole transporting layer of the third light emitting unit and the thickness of the hole transporting layer of the third light emitting unit is thicker than the thickness of the hole transporting layer of the second light emitting unit Gt; < / RTI > 17. The method of claim 16,
The thickness of the hole transport layer of the first light emitting unit is greater than about 1050 ANGSTROM and less than 1450 ANGSTROM, the thickness of the hole transport layer of the second light emitting unit is 200 ANGSTROM to 600 ANGSTROM, Wherein the thickness of the organic light emitting display is in a range of 800 to 1000 ANGSTROM. 17. The method of claim 16,
Wherein two of the first to third light emitting layers emit blue light and the remaining light emitting layers emit green light.

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