KR101926524B1 - Organic light emitting display device - Google Patents

Abstract

The present invention relates to an organic light emitting diode (OLED) display device capable of reducing a material cost and a driving voltage, and an organic light emitting diode (OLED) display device having high efficiency. The OLED display includes first and second electrodes opposing each other on a substrate, A first stack in which a hole injecting layer, a first hole transporting layer, a second hole transporting layer, a first light emitting layer, and a first electron transporting layer are sequentially stacked on the electrode, and a third hole transporting layer between the first stack and the second electrode, A second stack in which a fourth hole transporting layer, a second light emitting layer and a second electron transporting layer are sequentially stacked, and a charge generating layer formed between the first stack and the second stack to control charge balance between the respective stacks , The second light emitting layer is formed of at least three hosts and one phosphorescent dopant, and at least one of the three hosts is connected to the HOMO (Highest Occupied Molecular Orbital) level of the fourth hole transport layer and LUMO cupied molecular orbital) level is formed of the same material.

Description

BACKGROUND OF THE INVENTION 1. Field of the Invention [0001] The present invention relates to an organic light-

BACKGROUND OF THE INVENTION 1. Field of the Invention [0001] The present invention relates to an organic light emitting diode display, and more particularly, to a high efficiency organic light emitting diode display capable of reducing a material cost and a driving voltage.

The image display device that realizes various information on the screen is a core technology of the information communication age and it is becoming thinner, lighter, more portable and higher performance. Accordingly, an organic light emitting device displaying an image by controlling the amount of emitted light of an organic light emitting layer is being spotlighted by a flat panel display capable of reducing weight and volume, which is a disadvantage of a cathode ray tube (CRT).

Organic Light Emitting Device (OLED) is a self-luminous device using a thin light emitting layer between electrodes and has an advantage that it can be made thin like paper. Specifically, the organic light emitting device includes an anode, a hole injection layer (HIL), a hole transport layer (HTL), a light emitting layer, an electron transport layer (ETL), an electron injection layer Injection Layer (EIL), and a cathode.

In this case, when the phosphorescent dopant is doped into the light emitting layer, the dopant should be doped to 10 to 20% based on the thickness of the light emitting layer in order to increase the efficiency.

1b, the first curve 20 represents a case where a phosphorescent dopant is doped to the light emitting layer by 8% based on the thickness of the light emitting layer, and the second curve 22 represents a case where a phosphorescent dopant is added to the light emitting layer, The third curve 24 represents a case where the phosphorescent dopant is doped to the light emitting layer by 15% based on the thickness of the light emitting layer, the fourth curve 26 represents the case where the phosphorescent dopant is added to the light emitting layer, And 20% doping. As can be seen from the first to fourth curves 20, 22, 24 and 26, the higher the doping concentration, the higher the efficiency.

1A, it is necessary to have a doping concentration of 10% or more to form a high barrier between the hole transport layer 12 and the light emitting layer 10, and a part of the holes is directly injected into the HOMO level of the dopant due to the high energy barrier Therefore, the efficiency increases at a high doping concentration. Therefore, the dopant must be doped into the light emitting layer at a high concentration of 10% or more, which results in a high material efficiency and a driving voltage rise.

SUMMARY OF THE INVENTION The present invention has been made to solve the above problems, and it is an object of the present invention to provide a highly efficient organic light emitting diode display capable of reducing material cost and driving voltage.

The organic light emitting display according to the present invention includes a first electrode and a second electrode opposed to each other on a substrate, and a hole injecting layer, a first hole transporting layer, a second hole transporting layer, a first emitting layer, A first stack in which first electron transporting layers are sequentially stacked and a second stack in which a third hole transporting layer, a fourth hole transporting layer, a second light emitting layer, and a second electron transporting layer are sequentially stacked between the first stack and the second electrode And a charge generation layer formed between the first stack and the second stack to adjust the charge balance between the respective stacks, wherein the second light emitting layer is formed of at least three hosts and one dopant, and at least three The host of one of the hosts and the fourth hole transport layer is formed of a material having the same HOMO (Lowest Uncoupled Molecular Orbital) level and LUMO (Lowest Unoccupied Molecular Orbital) level.

Here, the at least three hosts are formed of first to third hosts having different HOMO levels and LUMO levels.

The first host has a first HOMO level and a first LUMO level, the second host has a second HOMO level and a second LUMO level, and the third host has a third HOMO level and a third LUMO level .

The second HOMO level may define a second hole transport path, and the third HOMO level may define a third hole transport path, wherein the second hole transport path is formed by the second HOMO level, And a path is formed.

The first host has the LUMO level of 2.0 eV to 2.4 eV and the triplet level of 2.6 eV to 3.2 eV.

The dopant of the second light emitting layer is doped with 1% to 7% based on the thickness or the volume ratio of the second light emitting layer.

The second host may be formed of a material having excellent electron mobility characteristics, and the third host may be formed of a material having excellent hole mobility characteristics.

In addition, a hole blocking layer may be further provided between the fourth hole transporting layer and the second emitting layer, or an electron blocking layer may be further provided between the second electron transporting layer and the second emitting layer.

The organic light emitting diode display according to the present invention includes a first electrode and a second electrode opposed to each other on a substrate, and a hole injecting layer, a first hole transporting layer, a second hole transporting layer, a light emitting layer, Transport layer is sequentially stacked, the light emitting layer is formed of at least three hosts and one dopant, and one of the at least three hosts and the second hole transport layer have a HOMO (Highest Occupied Molecular Orbital) And the LUMO (Lowest Unoccupied Molecular Orbital) level is formed of the same material.

Here, the at least three hosts are formed of first to third hosts having different HOMO levels and LUMO levels.

The first host has a first HOMO level and a first LUMO level, the second host has a second HOMO level and a second LUMO level, and the third host has a third HOMO level and a third LUMO level .

In addition, a first hole transporting path is formed in the light emitting layer by the first HOMO level, a second hole transporting path is formed by the second HOMO level, and a third hole transporting path is formed by the third HOMO level .

The first host has the LUMO level of 2.0 eV to 2.4 eV and the triplet level of 2.6 eV to 3.2 eV.

The dopant of the light emitting layer is doped to 1% to 7% based on the thickness or the volume ratio of the light emitting layer.

The second host may be formed of a material having excellent electron mobility characteristics, and the third host may be formed of a material having excellent hole mobility characteristics.

Further, a hole blocking layer may be further provided between the second hole transporting layer and the light emitting layer, or an electron blocking layer may be further provided between the electron transporting layer and the light emitting layer.

The OLED display according to the present invention includes a light emitting layer having a structure having at least three hosts and one dopant, so that hole injection from the hole transport layer to the host of the light emitting layer is smooth and luminous efficiency can be improved.

In addition, the organic light emitting display device according to the present invention dopes the light emitting layer with dopant at 1% to 7%. As described above, even if the doping concentration of the light emitting layer is as low as 1% to 7%, at least three hosts can provide various hole transporting paths, thereby achieving high efficiency. Even when the doping concentration is low, The material cost can be reduced.

Also, by having high efficiency even at a low doping concentration, it is possible to drive with a low driving voltage, and the lifetime can be extended accordingly.

FIG. 1A is a graph showing efficiency according to a doping concentration of a phosphorescent dopant, and FIG. 1B is a band diagram of a conventional organic light emitting device.
2 is a perspective view illustrating an organic light emitting diode according to a first embodiment of the present invention.
FIG. 3 is a band diagram of the organic light emitting device shown in FIG. 2. FIG.
4A is a comparative graph of luminescence spectra according to the phosphorescent dopant concentration.
FIG. 4B is a graph showing the efficiency according to the phosphorescent dopant concentration shown in FIG. 4A.
5 is a perspective view illustrating an organic light emitting diode according to a second embodiment of the present invention.
6 is a band diagram of the organic light emitting device shown in FIG.
7 is an equivalent circuit diagram of R, G and B pixels of a display device using an organic light emitting diode according to a second embodiment of the present invention.
8 is a cross-sectional view of a display device using the organic light emitting device shown in FIG.

Hereinafter, embodiments of the present invention will be described in detail with reference to the accompanying drawings. The configuration of the present invention and the operation and effect thereof will be clearly understood through the following detailed description. Before describing the present invention in detail, the same components are denoted by the same reference symbols as possible even if they are displayed on different drawings. In the case where it is judged that the gist of the present invention may be blurred to a known configuration, do.

Hereinafter, preferred embodiments of the present invention will be described in detail with reference to FIGS. 2 to 7. FIG.

FIG. 2 is a perspective view illustrating an organic light emitting device according to a first embodiment of the present invention, and FIG. 3 is a band diagram of the organic light emitting device shown in FIG.

2 and 3, the organic light emitting diode according to the first embodiment of the present invention includes a first electrode 240 and a second electrode 230, a first electrode 240, Stack structure including a first stack 210, a charge generation layer 222 and a second stack 220 stacked between the first and second electrodes 230. The organic light emitting device having a multi-stack structure includes light emitting layers of different colors in each stack, and light emitted from the light emitting layers of each stack is mixed to realize white light. The organic light emitting device according to the first embodiment of the present invention is formed by mixing blue light emitted from the first light emitting layer 218 and yellow-green light emitted from the second light emitting layer 226, Light is realized. 2 illustrates a bottom emission method in which light emitted from the first and second emission layers 218 and 226 is emitted downward. However, the organic light emitting device according to the first exemplary embodiment of the present invention may be a top emission type or a double- Light can be emitted in such a manner. Therefore, it is not limited thereto.

The first electrode 240 is formed of a transparent conductive material such as ITO (Indium Tin Oxide), IZO (Indium Zinc Oxide), or the like as a transparent conductive oxide (TCO) .

The second electrode 230 may be formed of gold (Au), molybdenum (Mo), chromium (Cr), copper (Cu), LiF or the like as a reflective metal such as aluminum.

The first stack includes a hole injection layer (HIL) 214, a first hole transport layer (HTL) 216a, and a second hole transport layer (HTL) 216b between the first electrode 240 and the charge generation layer 222, A hole transport layer 216b, a first emission layer (ETL) 218, and a first electron transport layer (ETL) 212 are sequentially stacked. At this time, the first light emitting layer 218 emits blue light to a light emitting layer containing a dopant of a blue fluorescent component in one host.

A charge generation layer (CGL) 122 is formed between the stacks to adjust the charge balance between the stacks. The charge generation layer 122 is adjacent to the N-type organic layer 222a and the second stack 220 that are positioned adjacent to the first stack 210 and inject electrons into the first stack 210, And a P-type organic layer 222b for injecting holes into the second stack 220.

The second stack 220 includes a third hole transport layer 224a, a fourth hole transport layer 224b, a second light emitting layer 226, a second electron transport layer 224b, and a third electron transport layer 224b between the second electrode 230 and the charge generating layer 222 228 are stacked in this order.

The second light emitting layer 226 has at least three hosts and one phosphorescence yellow-phosphorescence green. The dopant has a bandgap less than that of each of the band gaps (difference between HOMO level and LUMO level) of at least three hosts. At least three hosts are composed of first to third hosts (1Host, 2Host, 3Host) having different levels of Lowest Unoccupied Molecular Orbital (LUMO) and Highest Occupied Molecular Orbital (HOMO) levels. That is, the dopant has a LUMO level (dopant LUMO) lower than the LUMO level of the first through third hosts (1Host, 2Host, and 3Host) and a HOMO level higher than the HOMO levels of the first through third hosts (1Host, 2Host, Level. By having at least three hosts and one dopant structure, holes from the fourth hole transport layer 224b can be injected into the host of the second emission layer 226 smoothly.

3, the first host 1Host has a first HOMO level (first Host HOMO level) and a first LUMO level (one Host LUMO Level), and the first HOMO level and the first LUMO level are Is equal to the HOMO level and the LUMO level of the fourth hole transport layer 224b. The second host (2 Host) has a second HOMO level (2 Host HOMO Level) and a second LUMO level (2 Host LUMO Level), and the third host (3 Host) has a third HOMO level Level) and a third LUMO level (3 Host LUMO Level). The first host has a first HOMO level higher than the HOMO level of the second and third hosts and a first LUMO level higher than the LUMO level of the second and third hosts. The second host has a second LUMO level lower than the first and third LUMO levels of the first and third hosts and a second HOMO level lower than the first HOMO level of the first host. The third host has a third LUMO level higher than the second LUMO level of the second host and a third HOMO level lower than the second HOMO level of the second host.

As described above, the first hole transporting path is formed by the first HOMO level of the first host in the second light emitting layer 226, the second hole transporting path is formed by the second HOMO level of the second host, And the third hole transport path is formed by the third HOMO level of the host. As described above, since the paths of holes are formed in various ways through the first to third hosts, the holes from the fourth hole transport layer 224b can smoothly move to the second light emitting layer 226.

The first host may be formed of the same material as the material of the fourth hole transport layer 224b and may have a first LUMO level (4 HTL LUMO Level) and a HOMO level (4 HTL HOMO Level) of the fourth hole transport layer 224b, Level and a first HOMO level. That is, the first HOMO level of the first host and the HOMO level of the fourth hole transport layer 224b are the same, and the first LUMO level of the first host and the LUMO level of the fourth hole transport layer 224b are the same. Accordingly, the holes can be easily transferred from the fourth hole transport layer 224b to the second emission layer 226. [ Also, the first host uses a material having a first LUMO level of 2.0 eV to 2.4 eV and a triplet level (T1) of 2.6 eV to 3.2 eV, which is excellent in hole transporting characteristics. The second host is formed of a material having excellent electron mobility, the second LUMO level is lower than the first and third LUMO levels of the first and third hosts, the second LUMO level is lower than the first and third LUMO levels of the second and third host, Similar to the LUMO level, electrons can pass well from the second electron transport layer. The third host is formed of a material having excellent hole mobility.

The phosphorescent dopant of the second light emitting layer 226 is doped to 1% to 7% based on the thickness or the volume ratio of the second light emitting layer 226. In general, when the second light emitting layer is formed using the phosphorescent dopant, the dopant is doped to 10 to 15%. As described above, when the phosphorescent dopant is used, the dopant should be doped to 10% or more to obtain the optimum doping concentration. This is because when the hole is injected from the hole transporting layer to the light emitting layer, the injection of the dopant into the hole having a relatively lower barrier than the injection of the hole into the host in the light emitting layer is advantageous, .

However, the second light emitting layer 226 of the present invention has optimum conditions even at a low doping concentration of 1 to 7% because the hole transport path varies due to three kinds of hosts. As such, the first to third hosts of the second light emitting layer 226 form first through third hole transport paths through which the holes can be easily diffused from the fourth hole transport layer 224b, thereby forming the fourth hole transport layer 224b It is effective to alleviate the accumulation of holes at the interface of the second light emitting layer 226 and hence to improve the lifetime. This will be described with reference to Figs. 4A and 4B.

A hole blocking layer for preventing the diffusion of holes may be further provided between the fourth hole transport layer 224b and the second emission layer 226 or a hole blocking layer may be formed between the second electron transport layer 228 and the second emission layer 226. [ 226 may be further provided with an electron blocking layer for preventing electrons from diffusing. Both the hole blocking layer and the electron blocking layer can be formed, which can be changed according to the user's selection.

FIG. 4A is a graph showing a comparison of luminescence spectra according to the phosphorescent dopant concentration, and FIG. 4B is a graph showing efficiency according to the phosphorescent dopant concentration shown in FIG. 4A.

The second light emitting layer 226 according to the present invention has a high efficiency at a low doping concentration of phosphorescent dopant of 1 to 7%.

4A shows the dopant concentration of the second light emitting layer 226 in the multi-stack structure. In the first curve 44 shown in FIG. 4A, the phosphorescent dopant concentration is higher than that of the second light emitting layer 226 And the second curve 42 shows a graph according to the case where the phosphorescent dopant concentration is 9% based on the thickness of the second light emitting layer 226 And the third curve 40 is a graph showing a case where the phosphorescent dopant concentration is 6% based on the thickness of the second light emitting layer 226.

As shown in FIG. 4A, it can be seen that efficiency increases from the first curve 44 to the third curve 40. That is, the efficiency of the second curve 42 is higher than that of the first curve 44, and the efficiency of the third curve 40 is higher than that of the second curve 42. As the concentration of the phosphorescent dopant is lower, Is high.

[Table 1] shows the quantum efficiency (QE (%)) and the color coordinates (CIEx and CIEy) according to the dopant concentration.

density QE (%) CIEx CIEy 6% 20.5 0.443 0.547 9% 18.6 0.462 0.531 12% 18.0 0.481 0.513

As shown in Table 1 and FIG. 4B, the quantum efficiency was 20.5% when the phosphorescent dopant was doped to the second emissive layer 226 at 6%, and the phosphorescent dopant was doped to the second emissive layer 226 at 9% , The quantum efficiency is 18.6%, and the quantum efficiency is 18.0% when the second light emitting layer 226 is doped with the phosphorescent dopant at 12%. As described above, it can be seen that the quantum efficiency increases as the concentration of the phosphorescent dopant in the second light emitting layer 226 decreases.

FIG. 5 is a perspective view illustrating an organic light emitting device according to a second embodiment of the present invention, and FIG. 6 is a band diagram of the organic light emitting device shown in FIG.

Referring to FIGS. 5 and 6, the organic light emitting diode according to the second embodiment of the present invention is formed as a single stack including a first electrode 310, an organic layer, and a second electrode 330 on a substrate. When a voltage is applied between the first electrode 310 and the second electrode 330, electrons are injected from the first electrode 310 into the organic light emitting device through the second electrode 330, And is recombined in the light emitting layer 318 to generate an exciton. As a result, the exciton falls to a ground state and light is emitted. 5 shows a bottom emission method in which light emitted from the light emitting layer 318 is emitted downward. However, the organic light emitting device according to the second embodiment of the present invention emits light in a top emission type or a double- can do. Therefore, it is not limited thereto.

The first electrode 310 is formed of ITO (Indium Tin Oxide), IZO (Indium Zinc Oxide, IZO) or the like as a transparent conductive material such as TCO (Transparent Conductive Oxide .

The second electrode 330 may be formed of gold (Au), molybdenum (Mo), chrome (Cr), copper (Cu), LiF or the like as a reflective metal such as aluminum.

The organic layer includes a hole injection layer (HIL) 314, a first hole transport layer (HTL) 316a, a second hole transport layer 316b, a light emitting layer 318, an electron transport layer (ETL) 328 are sequentially stacked. A hole blocking layer may be further formed between the second hole transporting layer 316 and the light emitting layer 319 to prevent diffusion of holes or an electron blocking layer may be interposed between the electron transporting layer 328 and the light emitting layer 318. [ And an electron blocking layer for preventing diffusion. Both the hole blocking layer and the electron blocking layer can be formed, which can be changed according to the user's selection.

The light emitting layer 318 has at least three hosts and one phosphorescent dopant, and the dopant has a bandgap less than that of each of the band gaps (difference between the HOMO level and the LUMO level) of at least three hosts. At least three hosts are composed of first to third hosts (1Host, 2Host, 3Host) having different levels of Lowest Unoccupied Molecular Orbital (LUMO) and Highest Occupied Molecular Orbital (HOMO) levels. That is, the dopant has a LUMO level lower than the LUMO level of the first through third hosts (1Host, 2Host, and 3Host) and has a HOMO level higher than the HOMO level of the first through third hosts (1Host, 2Host, and 3Host). As described above, by having at least three hosts and one dopant structure, the holes from the second hole transport layer 316b are smoothly injected into the host of the light emitting layer 318.

Specifically, the first host 1Host has a first HOMO level (1 Host HOMO level) and a first LUMO level (1 Host LUMO Level), and the second host 2 Host has a second HOMO level Level and a second LUMO level, and the third host has a third HOMO level and a third LUMO level. As described above, since the paths of holes are formed in various ways through the first to third hosts, the holes from the second hole transport layer 316b smoothly move to the light emitting layer 318. [

The first host may be formed of the same material as the material of the second hole transporting layer 316b so that the LUMO level and the HOMO level of the second hole transporting layer 316b may be the same. That is, the first HOMO level of the first host and the HOMO level of the second hole transport layer 316b are the same, and the first LUMO level of the first host and the LUMO level of the second hole transport layer 316b are the same. Accordingly, holes can be easily transferred from the second hole transporting layer 316b to the light emitting layer 318. [ Also, the first host uses a material having a first LUMO level of 2.0 eV to 2.4 eV and a triplet level (T1) of 2.6 eV to 3.2 eV, which is excellent in hole transporting characteristics. The second host is formed of a material having excellent electron mobility and the second LUMO level is formed to be lower than the LUMO level of the first and third hosts so that electrons can be easily transferred from the second electron transport layer. The third host is formed of a material having excellent hole mobility. Further, the phosphorescent dopant of the light emitting layer 318 is doped to 1% to 7% based on the thickness or the volume ratio of the light emitting layer.

7 is an equivalent circuit diagram of R, G, and B pixels of a display device using an organic light emitting diode according to a second embodiment of the present invention, and FIG. 8 is a cross-sectional view of a display device using the organic light emitting device shown in FIG. to be.

The organic light emitting diode display according to the present invention includes a substrate having a display area defined by subpixels formed in a matrix form and a sealing substrate for protecting subpixels formed on the substrate from moisture or oxygen. The subpixels are formed into a passive matrix or an active matrix. In the case where the subpixels are formed in an active matrix type, this may be a structure including a switch transistor, a driving transistor, a capacitor, and an organic light emitting element, or a structure in which a transistor and a capacitor are further added. Here, the organic light emitting device according to the first and second embodiments can be used as the organic light emitting device, and the organic light emitting display using the organic light emitting device according to the second embodiment will be described as an example.

Referring to FIGS. 7 and 8, each of R, G, and B pixels of a display device using an organic light emitting diode according to an exemplary embodiment of the present invention includes a cell driver and an organic light emitting diode connected to the cell driver. Specifically, the R pixel includes an R cell driver connected to a gate line GL, a data line DL and a power supply line PL, a first organic light emitting element connected to the R cell driver, and a gate line A second organic light emitting element connected to the G cell driving unit and a gate line GL and a data line DL and a second organic light emitting element connected to the data line DL and the power supply line PL, A B cell driving unit connected to the power supply line PL, and a third organic light emitting device connected to the B cell driving unit. Such a display device includes red (R) light emitted from the light emitting layer of the first organic light emitting element of R pixel, green (G) light emitted from the light emitting layer of the organic light emitting element of the second organic light emitting element of G pixel, 3 blue light emitted from the light emitting layer of the organic light emitting element of the organic light emitting element is mixed to realize white light. The organic light emitting device according to the embodiment of the present invention emits light on the whole surface.

The R cell driver includes a first switch thin film transistor TS1 connected to a gate line GL and a data line DL and a second switch thin film transistor TS1 connected to the first switch thin film transistor TS1 and the power source line PL, A first driving thin film transistor TD1 connected to the one electrode 112 and a storage capacitor C1 connected between the power line PL and the drain electrode 138 of the first switch thin film transistor TS1 .

The G cell driver includes a second switch thin film transistor TS2 connected to the gate line GL and the data line DL and a second switch thin film transistor TS2 connected to the second switch thin film transistor TS2 and the power source line PL, A second driving thin film transistor TD2 connected to the one electrode 112 and a storage capacitor C2 connected between the power supply line PL and the drain electrode 158 of the second switch thin film transistor TS2 .

The B cell driver includes a third switch thin film transistor TS3 connected to the gate line GL and the data line DL and a third switch thin film transistor TS3 connected to the third switch thin film transistor TS3 and the power source line PL, A third driving thin film transistor TD3 connected to the one electrode 158 and a storage capacitor C3 connected between the power supply line PL and the drain electrode 178 of the third switch thin film transistor TS3 .

The first to third driving TFTs TD1 to TD3 include gate electrodes 132, 152 and 172 formed on an insulating substrate 101 as shown in FIG. 8, a gate insulating film covering the gate electrodes 132, 152 and 172, The semiconductor layers 136, 156 and 176 formed on the gate insulating film, the interlayer insulating film covering the semiconductor layers 136, 156 and 176 and the source regions 136S and 136B of the semiconductor layers 136, 156 and 176 through the first and second contact holes 130, 119, And source electrodes 134, 154 and 174 and drain electrodes 138, 158 and 178 connected to the drain regions 136D, 156D and 176D, respectively. The semiconductor layers 136, 156 and 176 are formed of an LTPS thin film and have channel regions 136C, 156C and 176C overlapped with the gate electrodes 132 and 152 and 172 and gate electrodes 132 Doped source regions 136S, 156S, and 176S and drain regions 136D, 156D, and 176D, which are not overlapped with the source regions 136A, In the present invention, the semiconductor layer is formed of the LTPS thin film, but the present invention is not limited thereto.

The first organic light emitting diode includes a first electrode 110 formed on a protective film covering the first driving TFT, a bank insulating film 142 formed with a hole for exposing the first electrode 110, A hole injection layer 112 formed on one electrode 110, a first hole transport layer 114, a second hole transport layer 116, a red light emitting layer 122R, an electron transport layer 118 and a second electrode 128 do. The red light emitting layer 122R has at least three hosts and one phosphorescent red dopant.

The second organic light emitting device includes a first electrode 112 formed on a protective film covering the second driving thin film transistor, a bank insulating film 142 formed with a hole for exposing the first electrode 112, A hole injection layer 112 formed on one electrode 112, a first hole transport layer 114, a second hole transport layer 116, a green light emitting layer 122G, an electron transport layer 118 and a second electrode 128 do. The green light emitting layer 122G has at least three hosts and one phosphorescent green dopant.

The third organic light emitting device includes a first electrode 112 formed on a protective film covering the third driving thin film transistor, a bank insulating film 142 formed with a pixel hole exposing the first electrode 112, A hole injection layer 112 formed on one electrode 112, a first hole transport layer 114, a second hole transport layer 116, a blue light emitting layer 122B, an electron transport layer 118 and a second electrode 128 do. The blue light emitting layer 122B has at least three hosts and one phosphorescent blue dopant.

Except for the color of each dopant, the light-emitting layers of the first to third organic light-emitting devices are formed in the same manner as the light-emitting layer of the organic light-emitting device according to the second embodiment of the present invention, so a detailed description thereof will be omitted.

The foregoing description is merely illustrative of the present invention, and various modifications may be made by those skilled in the art without departing from the spirit of the present invention. Accordingly, the embodiments disclosed in the specification of the present invention are not intended to limit the present invention. The scope of the present invention should be construed according to the following claims, and all the techniques within the scope of equivalents should be construed as being included in the scope of the present invention.

100: substrate 210: first stack
212: first electron transport layer 214, 314: hole injection layer
216a, 316a: first hole transport layer 216b, 316b: second hole transport layer
218: first light emitting layer 220: second stack
222: charge generation layer 222a: N-type charge generation layer
222b: P type charge generation layer 224a: Third hole transport layer
224b: fourth hole transporting layer 226: second light emitting layer
228: second electron transport layer 230, 330: second electrode
240, 310: first electrode 318: light emitting layer
328: electron transport layer

Claims (16)

First and second electrodes opposed to each other on a substrate;
A first stack in which a hole injecting layer, a first hole transporting layer, a second hole transporting layer, a first light emitting layer, and a first electron transporting layer are sequentially stacked on the first electrode;
A second stack in which a third hole transport layer, a fourth hole transport layer, a second light emitting layer, and a second electron transport layer are sequentially stacked between the first stack and the second electrode;
And a charge generation layer formed between the first stack and the second stack to adjust the charge balance between the respective stacks,
Wherein the second light emitting layer is formed of at least first to third hosts and one phosphorescent dopant,
Wherein the first host and the fourth hole transport layer have the same first HOMO level and first LUMO level,
The second host having an electron transporting property and having a second HOMO level lower than the first HOMO level and a second LUMO level lower than the first LUMO level,
The third host has a hole transportability and has a third HOMO level lower than the second HOMO level and a third LUMO level lower than the first LUMO level and higher than the second LUMO level,
Wherein the phosphorescent dopant has a fourth HOMO level lower than the first through third HOMO levels and a fourth LUMO level higher than the first through third LUMO levels.
delete delete The method according to claim 1,
The second light emitting layer
A first hole transport path is formed by the first HOMO level,
A second hole transport path is formed by the second HOMO level,
And a third hole transporting path is formed by the third HOMO level. The method according to claim 1,
Wherein the first host has a LUMO level of 2.0 eV to 2.4 eV and a triplet level of 2.6 eV to 3.2 eV. The method according to claim 1,
Wherein the phosphorescent dopant of the second light emitting layer is doped with 1% to 7% based on the volume ratio of the second light emitting layer.
delete The method according to claim 1,
A hole blocking layer may be further provided between the fourth hole transporting layer and the second light emitting layer,
And an electron blocking layer between the second electron transport layer and the second light emitting layer. First and second electrodes opposed to each other on a substrate;
An organic layer in which a hole injection layer, a first hole transport layer, a second hole transport layer, a light emitting layer, and an electron transport layer are sequentially stacked between the first electrode and the second electrode,
Wherein the light emitting layer is formed of at least first to third hosts and one phosphorescent dopant,
Wherein the first host and the second hole transport layer have the same first HOMO level and the first LUMO level,
The second host having an electron transporting property and having a second HOMO level lower than the first HOMO level and a second LUMO level lower than the first LUMO level,
The third host has a hole transportability and has a third HOMO level lower than the second HOMO level and a third LUMO level lower than the first LUMO level and higher than the second LUMO level,
Wherein the phosphorescent dopant has a fourth HOMO level lower than the first through third HOMO levels and a fourth LUMO level higher than the first through third LUMO levels.
delete delete 10. The method of claim 9,
The light-
A first hole transport path is formed by the first HOMO level,
A second hole transport path is formed by the second HOMO level,
And a third hole transporting path is formed by the third HOMO level. 10. The method of claim 9,
Wherein the first host has a LUMO level of 2.0 eV to 2.4 eV and a triplet level of 2.6 eV to 3.2 eV. 10. The method of claim 9,
Wherein the phosphorescent dopant of the light emitting layer is doped at 1% to 7% based on the volume ratio of the light emitting layer.
delete 10. The method of claim 9,
A hole blocking layer may be further provided between the second hole transporting layer and the light emitting layer,
And an electron blocking layer is further provided between the electron transporting layer and the light emitting layer.

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