KR20180038803A - Organic light emitting diode and Organic light emitting display device including the same - Google Patents

Abstract

The present invention relates to an organic light emitting diode and an organic light emitting display device including the same. The organic light emitting diode comprises: a first electrode; a hole transport layer; a first light emitting material layer; an electron transport layer; and a second electrode. Since red and green light emitting material layers include a hole injection material, the organic light emitting diode and the organic light emitting display device including the same can solve problem of blue light emitting in red and green pixel regions without having deterioration of light emitting efficiency and lifetime degradation in a blue pixel region.

Description

[0001] The present invention relates to an organic light emitting diode (OLED) and an organic light emitting diode (OLED)

The present invention relates to an organic light emitting diode. More particularly, the present invention relates to an organic light emitting diode having a blue common light emitting layer, an organic light emitting diode capable of suppressing blue light emission in red and green pixel regions, Emitting diode and an organic light emitting display including the same.

As the information society develops, the demand for display devices for displaying images is increasing in various forms. A liquid crystal display (LCD) device, a plasma display panel (PDP), or an organic light emitting diode (OLED), which is thinner and lighter than a conventional cathode ray tube (CRT) )) Display device is actively researched and commercialized.

Of the above flat panel display devices, the organic light emitting diode display device includes an organic light emitting diode as an essential component, and a lightweight thin type is possible because a backlight used in a liquid crystal display device, which is a non-light emitting device, is not required. In addition, it is advantageous in terms of power consumption as compared with liquid crystal display devices, has low voltage driving capability, and has a high response speed.

For example, the organic light emitting diode includes a hole injection layer (HIL), a hole transporting layer (HTL), an emitting material layer (EML), and an electron transporting layer an electron transporting layer, and an electron injection layer (EIL). The hole injection layer, the hole transport layer, the light emitting material layer, the electron transport layer, and the electron injection layer are formed by a deposition process.

On the other hand, a hybrid organic light emitting diode has been proposed in which a large area organic light emitting diode can not be manufactured by a deposition process, and thus a part of the organic light emitting diode is formed by a soluble process.

1 is a schematic cross-sectional view of a conventional hybrid type organic light emitting diode.

1, the organic light emitting diode 10 includes a first electrode 20, a second electrode 30 facing the first electrode 20, a first electrode 20 and a second electrode 30, A hole transporting layer 44, a red light emitting material layer 52, a green light emitting material layer 54, a blue light emitting material layer 56 and an electron transporting layer 60, .

The first electrode 20 may be made of a material having a large work function value, for example, a transparent conductive material, and may be used as an anode. The second electrode 30 may be made of a metal having a low work function value and may be used as a cathode. For example, the first electrode 20 may be made of indium-tin-oxide (ITO) or indium-zinc-oxide (IZO) (30) may be made of any one of aluminum (Al), magnesium (Mg), and aluminum-magnesium alloy (AlMg).

1 and 2, the first and second electrodes 20 and 30 are integrally formed in the red, green, and blue pixel regions Rp, Gp, and Bp. However, the first and second electrodes 20 and 30, 30 are separately formed for each pixel region Rp, Gp, Bp.

The hole injection layer 42 and the hole transport layer 44 are sequentially stacked corresponding to the red, green and blue pixel regions Rp, Gp and Bp, and the red light emitting material layer 52 and the blue light emitting material A layer 54 is formed in the red and green pixel regions Rp and Gp, respectively.

The hole injection layer 42, the hole transport layer 44, the red light emitting material layer 52, and the blue light emitting material layer 54 are formed by a solution process.

Meanwhile, the blue light emitting material layer 56 is formed corresponding to all of the red, green, and blue pixel regions Rp, Gp, and Bp. That is, the blue light emitting material layer 56 is formed on the red light emitting material layer 52 of the red pixel region Rp, the blue light emitting material layer 54 of the green pixel region Gp, The hole transport layer 44 is formed.

The electron transport layer 60 and the second electrode 30 are sequentially stacked on the blue light emitting material layer 56.

At this time, the blue light emitting material layer 56 and the electron transporting layer 60 are formed by a deposition process.

Since the hole injecting layer 42, the hole transporting layer 44, the red light emitting material layer 52, and the green light emitting material layer 54 are formed by the solution process, A large area organic light emitting diode 10 can be manufactured.

However, in the conventional hybrid type organic light emitting diode 10, blue light is emitted in the red and green pixel regions Rp and Gp, and the display quality of the organic light emitting diode 10 is degraded.

In the present invention, a problem of display quality deterioration in a conventional hybrid type organic light emitting diode is solved.

According to an aspect of the present invention, there is provided a light emitting device including a first light emitting material layer located in a first pixel region and including a hole blocking material, and a second light emitting material layer corresponding to first and second pixel regions, The HOMO value of the hole blocking material is smaller than the HOMO value of the host and the dopant and the LUMO value of the hole blocking material is larger than the LUMO value of the host and the dopant.

According to another aspect of the present invention, there is provided a light emitting device including a first light emitting material layer located in a first pixel region and including a hole blocking material, and a second light emitting material layer corresponding to first and second pixel regions, Wherein each of X ₁ , X ₂ and X ₃ is carbon or nitrogen, at least one of X ₁ , X ₂ and X ₃ is nitrogen, each of Ar ₁ , Ar ₂ and Ar ₃ is a substituted or unsubstituted C An aryl of ₆ to ₆₀ carbon atoms, a substituted or unsubstituted C ₅ to C ₅₀ heteroaryl, and at least one of Ar ₁ , Ar ₂ , and Ar ₃ is dibenzofuran or a carbazole.

The present invention also provides an OLED display device including a substrate, the above-described organic light emitting diode positioned above the substrate, and a thin film transistor located between the substrate and the organic light emitting diode and connected to the organic light emitting diode .

Further, in the present invention, the hole blocking layer is provided between the red and green luminescent material layers and the blue luminescent material layer, thereby solving the blue luminescent problem in the red and green pixel regions.

Further, in the present invention, the blue light emission problem in the red and green pixel regions can be solved without the luminous efficiency and lifetime degradation in the blue pixel region by including the hole injection material in the red and green light emitting material layers.

1 is a schematic cross-sectional view of a conventional hybrid type organic light emitting diode.
2 is a graph showing an emission spectrum of a conventional hybrid-type organic light emitting diode in a red pixel region.
3 is a schematic circuit diagram of an organic light emitting diode display according to the present invention.
4 is a schematic cross-sectional view of an OLED display according to the present invention.
5 is a schematic cross-sectional view of an organic light emitting diode according to a first embodiment of the present invention.
6 is a graph illustrating the efficiency of light emission in the blue pixel region of the organic light emitting diode according to the first embodiment of the present invention.
7 is a graph showing lifetime of the organic light emitting diode in the blue pixel region according to the first embodiment of the present invention.
8 is a schematic cross-sectional view of an organic light emitting diode according to a second embodiment of the present invention.
FIG. 9A is a graph showing an emission spectrum in a red pixel region of an organic light emitting diode according to a second embodiment of the present invention, and FIG. 9B is an enlarged view of a portion "A" in FIG. 9A.
10 is a graph showing the lifetime of the organic light emitting diode in the red pixel region according to the second embodiment of the present invention.

Since the blue light emitting material having the desired luminous efficiency has not been developed by the solution process, the blue light emitting material layer (56 in FIG. 1) is formed by the vapor deposition process, so that blue light emission is observed in the red and green pixel regions.

1, in the red and green pixel regions Rp and Gp, the red and green luminescent material layers 52 and 54 are in contact with the hole transport layer 44 while the red and green luminescent material layers 52 and 54 are in contact with the hole transport layer 44, 54 and the electron transport layer 60, a blue light emitting material layer 56 is present.

Therefore, in the red and green pixel regions Rp and Gp, holes and electrons can be combined in the blue light emitting material layer 56, and blue light emission is observed in the red and green pixel regions Rp and Gp.

Referring to FIG. 2, which is a graph showing the emission spectrum in the red pixel region of the conventional hybrid type organic light emitting diode, blue light emission occurs in the red pixel region, thereby deteriorating the display quality of the OLED display.

In order to solve such a problem, the present invention provides a liquid crystal display device comprising: a substrate on which first and second pixel regions are defined; a first electrode positioned in each of the first and second pixel regions; A first light emitting material layer disposed on the hole transporting layer in correspondence to the first pixel region and including a host, a dopant and a hole blocking material; A second light emitting material layer disposed on the hole transporting layer of the second pixel region, and an electron transporting layer and a second electrode sequentially stacked on the second common light emitting layer, wherein the hole blocking material The HOMO value is less than the HOMO value of the host and the dopant, and the LUMO value of the hole blocking material is greater than the LUMO value of the host and the dopant.

In the organic light emitting diode of the present invention, the hole blocking material may be represented by the following formula: wherein each of X ₁ , X ₂ and X ₃ is carbon or nitrogen, at least one of X ₁ , X ₂ and X ₃ is nitrogen, Ar Each of Ar ₁ , Ar ₂ and Ar _{3 is} selected from substituted or unsubstituted C ₆ to C ₆₀ aryl or substituted or unsubstituted C ₅ to C ₅₀ heteroaryl, and at least one of Ar ₁ , Ar ₂ and Ar ₃ One is dibenzofuran or carbazole.

According to another aspect of the present invention, there is provided a liquid crystal display device comprising: a first electrode disposed on a substrate on which first and second pixel regions are defined, the first electrode being located in each of the first and second pixel regions; A first light emitting material layer disposed on the hole transporting layer and corresponding to the first pixel region and including a hole blocking material; a second light emitting material layer disposed on the first light emitting material layer, A second light emitting material layer positioned on the hole transporting layer in the pixel region, and an electron transporting layer and a second electrode sequentially deposited on the second common light emitting layer, wherein the hole blocking material is represented by the following formula: X ₁ , X ₂ and X ₃ are each carbon or nitrogen and at least one of X ₁ , X ₂ and X ₃ is nitrogen and each of Ar ₁ , Ar ₂ and Ar ₃ is a substituted or unsubstituted C ₆ to C ₆₀ aryl or in the heteroaryl group of the substituted or unsubstituted C ₅ ~ C ₅₀ It is chosen, and Ar _1, Ar _2, at least one of Ar ₃ provides dibenzofuran or carbazole candied organic light emitting diode.

In the organic light emitting diode of the present invention, the hole blocking material is one of the following materials.

In the organic light emitting diode of the present invention, the HOMO value of the hole blocking material is -6.5 to -5.5 eV, and the LUMO value of the hole blocking material is -3.0 to -2.0 eV.

In the organic light emitting diode of the present invention, the hole blocking material has a concentration gradient in the first luminescent material layer.

In the organic light emitting diode of the present invention, the hole blocking material in the first light emitting material layer has a weight ratio of 5 to 10%.

According to another aspect of the present invention, there is provided an organic light emitting display comprising: a substrate; an organic light emitting diode disposed above the substrate; and a thin film transistor disposed between the substrate and the organic light emitting diode and connected to the organic light emitting diode. A display device is provided.

In the organic light emitting diode display of the present invention, the hole blocking material has a concentration gradient in the first luminescent material layer.

In the organic light emitting diode display of the present invention, the hole blocking material in the first light emitting material layer has a weight ratio of 5 to 10%.

Hereinafter, the present invention will be described in detail with reference to the drawings.

3 is a schematic circuit diagram of an organic light emitting diode display according to the present invention.

3, a gate line GL, a data line DL, and a power line PL are formed to intersect with each other to define a pixel region P, and the pixel region P, a switching thin film transistor Ts, a driving thin film transistor Td, a storage capacitor Cst, and an organic light emitting diode D are formed.

The switching thin film transistor Ts is connected to the gate line GL and the data line DL and the driving thin film transistor Td and the storage capacitor Cst are connected to the switching thin film transistor Ts and the power line DL, And is connected between the wiring lines PL. The organic light emitting diode D is connected to the driving thin film transistor Td.

In this organic light emitting diode display device, when the switching thin film transistor Ts is turned on according to a gate signal applied to the gate line GL, the data signal DL applied to the data line DL Is applied to the gate electrode of the driving thin film transistor Td and one electrode of the storage capacitor Cst through the switching thin film transistor Ts.

The driving thin film transistor Td is turned on according to a data signal applied to the gate electrode so that a current proportional to the data signal is supplied from the power wiring PL to the organic thin film transistor Td through the driving thin film transistor Td, And the organic light emitting diode D emits light with a luminance proportional to the current flowing through the driving thin film transistor Td.

At this time, the storage capacitor Cst is charged with a voltage proportional to the data signal so that the voltage of the gate electrode of the driving thin film transistor Td is kept constant during one frame.

Therefore, the organic light emitting display device can display a desired image.

4 is a schematic cross-sectional view of an OLED display according to the present invention.

4, a driving thin film transistor Td and an organic light emitting diode D connected to the driving thin film transistor Td are disposed on a substrate 150. [

The substrate 150 may be a glass substrate or a polymer such as polyimide.

Although not shown, a buffer layer made of an inorganic insulating material such as silicon oxide or silicon nitride may be formed on the substrate 150.

The driving thin film transistor Td is connected to the switching thin film transistor and includes a semiconductor layer 152, a gate electrode 160, a source electrode 170 and a drain electrode 172.

The semiconductor layer 152 is formed on the flexible substrate 110, and may be formed of an oxide semiconductor material or polycrystalline silicon.

When the semiconductor layer 152 is formed of an oxide semiconductor material, a light shielding pattern (not shown) may be formed under the semiconductor layer 152, and the light shielding pattern may prevent light from being incident on the semiconductor layer 152. Thereby preventing the semiconductor layer 152 from being deteriorated by light. Alternatively, the semiconductor layer 152 may be made of polycrystalline silicon. In this case, impurities may be doped on both edges of the semiconductor layer 152.

A gate insulating layer 154 made of an insulating material is formed on the entire surface of the flexible substrate 110 on the semiconductor layer 152. The gate insulating layer 154 may be formed of an inorganic insulating material such as silicon oxide or silicon nitride.

A gate electrode 160 made of a conductive material such as metal is formed on the gate insulating layer 154 to correspond to the center of the semiconductor layer 152. The gate electrode 160 is connected to the switching thin film transistor.

The gate insulating layer 154 may be formed on the entire surface of the flexible substrate 110. The gate insulating layer 154 may be patterned to have the same shape as the gate electrode 160. [

An interlayer insulating layer 162 made of an insulating material is formed on the entire surface of the substrate 150 on the gate electrode 160. The interlayer insulating layer 162 may be formed of an inorganic insulating material such as silicon oxide or silicon nitride, or may be formed of an organic insulating material such as benzocyclobutene or photo-acryl.

The interlayer insulating layer 162 has first and second contact holes 164 and 166 that expose both sides of the semiconductor layer 152. The first and second contact holes 164 and 166 are spaced apart from the gate electrode 160 on both sides of the gate electrode 160.

Here, the first and second contact holes 164 and 166 are also formed in the gate insulating film 154. Alternatively, when the gate insulating layer 154 is patterned to have the same shape as the gate electrode 160, the first and second contact holes 164 and 166 may be formed only in the interlayer insulating layer 162 .

A source electrode 170 and a drain electrode 172 made of a conductive material such as a metal are formed on the interlayer insulating layer 162.

The drain electrode 172 and the source electrode 170 are spaced apart from each other around the gate electrode 160 and are electrically connected to the semiconductor layer 152 through the first and second contact holes 164 and 166, As shown in Fig. The source electrode 170 is connected to the power wiring (PL in Fig. 3).

The semiconductor layer 152 and the gate electrode 160, the source electrode 170 and the drain electrode 172 constitute the driving thin film transistor Td, The gate electrode 160, the source electrode 170, and the drain electrode 172 are located on the upper surface of the gate electrode 152.

Alternatively, the driving thin film transistor Td may have an inverted staggered structure in which a gate electrode is located below the semiconductor layer and a source electrode and a drain electrode are located above the semiconductor layer. In this case, the semiconductor layer may be made of amorphous silicon.

Meanwhile, the switching thin film transistor (not shown) may have substantially the same structure as the driving thin film transistor Td.

A protective layer 174 having a drain contact hole 176 exposing the drain electrode 172 of the driving thin film transistor Td is formed to cover the driving thin film transistor Td.

A first electrode 110 connected to the drain electrode 172 of the driving TFT Td through the drain contact hole 176 is formed on the protective layer 174 for each pixel region.

The first electrode 110 may be an anode and may be formed of a conductive material having a relatively large work function value. For example, the first electrode 110 may be made of a transparent conductive material such as indium-tin-oxide (ITO) or indium-zinc-oxide (IZO) .

Meanwhile, when the organic light emitting diode display of the present invention is a top emission type, a reflective electrode or a reflective layer may be further formed under the first electrode 110. For example, the reflective electrode or the reflective layer may be formed of an aluminum-palladium-copper (APC) alloy.

A bank layer 115 covering the edge of the first electrode 110 is formed on the passivation layer 174. The bank layer 115 exposes the center of the first electrode 110 corresponding to the pixel region.

An organic light emitting layer 130 is formed on the first electrode 110. The specific structure of the organic emission layer 130 will be described later.

The second electrode 140 is formed on the substrate 150 on which the organic light emitting layer 130 is formed. The second electrode 140 covers the entire surface of the display region and is made of a conductive material having a relatively small work function value and can be used as a cathode. For example, the second electrode 140 may be formed of any one of aluminum (Al), magnesium (Mg), and aluminum-magnesium alloy (AlMg).

The first electrode 110, the organic light emitting layer 130, and the second electrode 140 form an organic light emitting diode (D).

In the present invention, a part of the organic light emitting layer 130 is formed by a solution process, and the remainder is formed by deposition fixation to have a hybrid structure.

5 is a schematic cross-sectional view of an organic light emitting diode according to a first embodiment of the present invention.

As shown in FIG. 5, the organic light emitting diode D according to the first embodiment of the present invention includes first and second electrodes 110 and 140 facing each other, and first and second electrodes 110 and 120, A red light emitting material layer 122 and a green light emitting material layer 124 located between the red and green pixel regions Rp and Gp and the red and green light emitting material layers 122 and 124, A hole blocking layer (HBL) 132 formed to cover the red, green and blue pixel regions Rp, Gp and Bp and a hole blocking layer 132 formed between the hole blocking layer 132 and the second electrode 140 And a blue light emitting layer 126 formed corresponding to the red, green, and blue pixel regions Rp, Gp, and Bp.

That is, the hole blocking layer 132 is located between each of the red and green light emitting layers 122 and 126 and the blue light emitting layer 126.

A hole injection layer 112 and a hole transport layer 114 may be sequentially stacked on the first electrode 110 to correspond to the red, green, and blue pixel regions Rp, Gp, and Bp, The electron transport layer 134 may be formed between the first electrode 126 and the second electrode 140 corresponding to the red, green, and blue pixel regions Rp, Gp, and Bp.

The hole injection layer 112, the hole transport layer 114, the red light emitting material layer 122, the green light emitting material layer 124, the blue light emitting material layer 126, the hole blocking layer 132, The electron transport layer 134 constitutes an organic light emitting layer 130.

Here, the hole injection layer 112, the hole transport layer 114, the red light emitting material layer 122, and the green light emitting material layer 124 are formed by a solution process, The blue light emitting material layer 132, the blue light emitting material layer 126, and the electron transporting layer 134 are formed by a deposition process.

The hole blocking layer 132 in the organic light emitting diode D according to the first embodiment of the present invention is disposed between the red light emitting material layer 122 and the blue light emitting material layer 126 in the red pixel region Rp, And is positioned between the green light emitting material layer 124 and the blue light emitting material layer 126 in the pixel region Gp and between the hole transporting layer 114 and the blue light emitting material layer 124 in the blue pixel region Bp.

Therefore, in the red and green pixel regions Rp and Gp, the holes are prevented from reaching the blue light emitting material layer 126 through the red and green light emitting material layers 122 and 124 by the hole blocking layer 132, Blue light emission is prevented in the red and green pixel regions Rp and Gp.

In the blue pixel region Bp, however, hole transport from the hole transport layer 114 to the blue light emitting material layer 126 is inhibited by the hole blocking layer 132. Therefore, the luminous efficiency and lifetime of the blue pixel region Bp are lowered.

6, which is a graph showing the luminous efficiency in the blue pixel region of the organic light emitting diode according to the first embodiment of the present invention, compared with the conventional organic light emitting diode (without HBL) having no hole blocking layer, The luminous efficiency of the blue pixel region (Bp in FIG. 5) in the organic light emitting diode (HBL applied) according to the first embodiment of the present invention forming the layer (132 in FIG.

7, which is a graph showing lifetime in the blue pixel region of the organic light emitting diode according to the first embodiment of the present invention, a blue pixel region (FIG. 5) is formed according to the formation of the hole blocking layer Bp) is also greatly reduced.

5, the hole blocking layer 132 is interposed between each of the red and green luminescent material layers 122 and 124 and the blue luminescent material layer 126 in the red and green pixel regions Rp and Gp, Light emission in the blue light emitting material layer 126 located in the red and green pixel regions Rp, Gp is prevented. Therefore, blue light emission is prevented in the red and green pixel regions Rp and Gp and the display quality of the organic light emitting display (100 in Fig. 4) is improved.

However, in the blue pixel region Bp, there is a problem that the luminous efficiency and lifetime of the blue pixel region Bp are reduced by interposing the hole blocking layer 132 between the hole transport layer 114 and the blue light emitting material layer 126 .

8 is a schematic cross-sectional view of an organic light emitting diode according to a second embodiment of the present invention.

8, the organic light emitting diode D according to the second embodiment of the present invention includes first and second electrodes 210 and 240 facing each other, a first electrode 210 and a second electrode 210, A red light emitting material layer 222 and a green light emitting material layer 224 located between the red and green pixel regions Rp and Gp and the red and green light emitting material layers 222 and 224, And a blue light emitting layer 126 formed covering the red, green, and blue pixel regions Rp, Gp, and Bp.

At this time, each of the red and green light emitting material layers 222 and 224 includes a hole blocking material 223. That is, each of the red and green luminescent material layers 222 and 224 includes a host (not shown), a dopant (not shown), and a hole blocking material 223. In other words, the sum of the weight ratio of the host, the dopant, and the hole blocking material 223 in each of the red and green light emitting material layers 222 and 224 is 100%.

Meanwhile, the blue light emitting material layer 226 includes only a host (not shown) and a dopant (not shown) without a hole blocking material. That is, the sum of the weight ratio of the host and the dopant in the blue light emitting material layer 226 is 100%.

A hole injection layer 212 and a hole transport layer 214 may be sequentially stacked on the first electrode 210 to correspond to the red, green, and blue pixel regions Rp, Gp, and Bp, The electron transport layer 234 may be formed between the first electrode 226 and the second electrode 240 to correspond to the red, green, and blue pixel regions Rp, Gp, and Bp.

The hole injection layer 212, the hole transport layer 214, the red light emitting material layer 222, the green light emitting material layer 224, the blue light emitting material layer 226, Thereby forming a light emitting layer 230.

Here, the hole injection layer 212, the hole transport layer 214, the red light emitting material layer 222 and the green light emitting material layer 224 are formed by a solution process, The layer 226 and the electron transport layer 234 are formed by a deposition process.

The highest occupied molecular orbital (HOMO) value of the hole blocking material 223 is smaller than the HOMO value of the host and the dopant, and the lowest unoccupied molecular orbital of the hole blocking material 223 Orbital, LUMO) value is larger than the LUMO value of the host and the dopant.

For example, the HOMO value of the hole blocking material 223 may be -6.5 to -5.5 eV, preferably -6.5 to -6.0 eV. The LUMO value of the hole blocking material 223 may be -3.0 to -2.0 eV, preferably -2.5 to -2.0 eV.

 Therefore, holes are prevented from being transferred from the red and green pixel regions Rp and Gp to the blue light emitting material layer 226 by the hole blocking material 223.

That is, in the organic light emitting diode D according to the second embodiment of the present invention, the red and green luminescent material layers 222 and 224 include the hole blocking material 223 and the holes are converted into the blue luminescent material layer 226 And blue light emission in the red and green pixel regions Rp, Gp is prevented. Therefore, the display quality of the organic light emitting display (100 in Fig. 4) is improved.

The hole blocking material 223 may have a concentration gradient or a density gradient in each of the red and green light emitting material layers 222 and 224. That is, in each of the red and green luminescent material layers 222 and 224, the hole blocking material 223 is smaller than the upper area adjacent to the blue luminescent material layer 226 in the lower region close to the hole transporting layer 214 Concentration (or density). Accordingly, hole transport to the blue light emitting material layer 226 can be suppressed without interfering with the combination of holes and electrons in the red and green light emitting material layers 222 and 224, respectively.

Since the blue light emitting material layer 226 does not include the hole blocking material 223, hole transport from the hole transporting layer 214 to the blue light emitting material layer 226 in the blue pixel region Bp It is not disturbed.

Accordingly, problems of luminous efficiency and life span in the blue pixel region generated in the organic light emitting diode and the OLED display according to the first embodiment of the present invention are solved.

For example, in each of the red and green emissive material layers 222 and 224, the host has a first weight ratio, the dopant has a second weight ratio that is less than the first weight ratio, the hole blocking material 223, May have a third weight ratio that is less than the second weight ratio. The first weight ratio may be about 50 to 90%, the second weight ratio may be about 5 to 30%, and the third weight ratio may be about 1 to 20%. Preferably, the third weight ratio may be about 5 to 10%.

Since the HOMO value of the hole blocking material 223 is smaller than the HOMO value of the host and the LUMO value is smaller than the LUMO value of the host, the hole blocking material 223 is not used as a dopant since it does not participate in light emission. It does not. Further, it is understood that the hole blocking material 223 is not used as a host since it has a weight ratio smaller than that of the dopant.

The hole blocking material 223 may be represented by the following formula (1).

[Chemical Formula 1]

In Formula 1, each of X ₁ , X ₂ , and X ₃ is carbon or nitrogen, and at least one of X ₁ , X ₂ , and X ₃ is nitrogen.

Each of Ar ₁ , Ar ₂ and Ar ₃ is a substituted or unsubstituted C ₆ to C ₆₀ aryl or substituted or unsubstituted C ₅ to C ₅₀ heteroaryl, And at least one of Ar ₁ , Ar ₂ and Ar ₃ is a dibenzofuran or a carbazole.

For example, the hole blocking material 223 may be any one of a plurality of materials represented by the following formula (2).

(2)

Synthetic example

1. Synthesis of Compound A

[Reaction Scheme 1]

(5 g, 10.1 mmol), compound b (2.57 g, 12.1 mmol), palladium (II) acetate (Pd (OAc) ₂ ) (0.11 g, 5 mol%), 2-dicyclohexylphosphino-2 a ', 4', 6'-triisopropylbiphenyl (XPhos) (0.96 g, 2.02 mmol), Cs 2 CO 3 (6.58 g, 20.2 mmol), toluene / ethanol / H 2 O (50 ml / 5 ml / 5 ml) And the mixture was stirred at 100 DEG C for 12 hours.

 After completion of the reaction, the reaction mixture was extracted with methylene chloride and filtered using MgSO4. The solvent was removed from the obtained organic layer and then purified by column chromatography (Hexane: EA (ethylene acetate) = 10: 1 (by volume)) to obtain Compound A (4.68 g, yield 74%). (GC-Mass theoretical value: 625.24 g / mol, GC-Mass measurement: 625 g / mol)

2. Synthesis of Compound B

[Reaction Scheme 2-1]

Compound in a nitrogen stream c (11.64 g, 40.39 mmol) , compound d (5 g, 18.36 mmol) , Palladium-tetrakis (triphenylphosphine), (Pd (PPh 3) 4) (1.06 g, 5 mol%), K 2 CO ₃ (12.69 g, 91.8 mmol) and THF (tetrahydrofuran) / H ₂ O (100 ml / 50 ml) were mixed and stirred at 80 ° C for 12 hours.

After completion of the reaction, the mixture was extracted with EA and filtered using MgSO ₄ . The solvent was removed from the obtained organic layer and then purified by column chromatography (Hexane: EA = 5: 1) to obtain a compound e (8.69 g, yield 79%).

[Reaction Scheme 2-2]

(3.69 g, 17.41 mmol), Pd (OAc) ₂ (0.16 g, 5 mol%), XPhos (1.38 g, 2.9 mmol), Cs ₂ CO ₃ (9.45 g, 29.01 mmol) and toluene / ethanol / H ₂ O (100 ml / 10 ml / 10 ml) were mixed and stirred at 100 ° C for 12 hours.

After completion of the reaction, the reaction mixture was extracted with methylene chloride and filtered using MgSO ₄ . The solvent was removed from the obtained organic layer and then purified by column chromatography (Hexane: EA = 10: 1) to obtain Compound B (7.17 g, yield 69%).

(GC-Mass theoretical value: 715.25 g / mol, GC-Mass measurement: 715 g / mol)

3. Synthesis of Compound C

[Reaction Scheme 3]

(5 g, 18.36 mmol), Pd (OAc) ₂ (0.42 g, 5 mol%), XPhos (5.26 g, 11.02 mmol), Cs ₂ CO ₃ (29.91 g, 91.8 mmol) and toluene / ethanol / H ₂ O (100 ml / 10 ml / 10 ml) were mixed and stirred at 100 ° C for 12 hours.

After completion of the reaction, the reaction mixture was extracted with methylene chloride and filtered using MgSO ₄ . The solvent was removed from the obtained organic layer and then purified by column chromatography (Hexane: EA = 10: 1) to obtain Compound C (7.7 g, yield 52%).

(GC-Mass theoretical value: 805.26 g / mol, GC-Mass measurement: 805 g / mol)

Organic light emitting diode

In the organic light emitting diode according to the second embodiment of the present invention (D of FIG. 8), when the red light emitting material layer contains only the host and the dopant without the hole blocking material (comparative example) And the hole blocking material (10 wt%) (experimental example) were measured.

[Table 1]

As shown in Table 1, the color coordinates and lifetime of the organic light emitting diode of the experimental example including the hole blocking material were improved.

Referring to FIG. 9A, which is a partial enlarged view of FIG. 9A and FIG. 9A, which is a graph showing the emission spectrum in the red pixel region of the organic light emitting diode according to the second embodiment of the present invention, By including the material, it can be seen that the blue peak in the red pixel region has disappeared.

Also, as shown in Table 1 and FIG. 10, the lifetime of the organic light emitting diode increases because the red light emitting material layer includes the hole blocking material. This is because the recombination zone of electrons and holes is formed within the red light emitting material layer .

The red light emitting material layer was formed by adding 10 wt% of each of the compounds A, B, and C as the hole blocking material, and the luminescent characteristics in the organic light emitting diode were measured.

[Table 2]

As shown in Table 2, it can be seen that the color coordinates are improved in both cases where the red light emitting material layer contains the compounds A, B, and C.

The red luminescent material layer was formed while changing the weight ratio of the compound B as the hole blocking material, and the luminescent characteristics in the organic light emitting diode were measured and are shown in Table 3.

[Table 3]

As shown in Table 3, when the hole blocking material had a weight ratio of 5 to 10%, the color coordinates were greatly improved under a driving voltage rising condition of a certain range.

In other words, in the organic light emitting diode D according to the second embodiment of the present invention, the first luminescent material layer (red or green luminescent material layer) formed in the first pixel region (red or green pixel region) And a second light emitting material layer (blue light emitting material layer) which is a light emitting layer of the second pixel region (blue pixel region) is formed corresponding to the entire first and second pixel regions, The problem of degradation of the display quality in the first pixel region is prevented by the hole blocking material without deteriorating the efficiency and the lifetime.

That is, in the organic light emitting diode and the OLED display according to the second embodiment of the present invention, the red and green luminescent material layers include a hole blocking material, and holes are transmitted to the blue luminescent material layer located in the red and green pixel regions . Therefore, deterioration of display quality due to blue light emission in the red and green pixel regions can be prevented.

In addition, since the hole blocking material is not included in the blue light emitting material layer, the problem of the luminous efficiency and life span in the blue light emitting material layer is prevented.

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 as defined in the appended claims. It can be understood that

110, 210: first electrode 112, 212: hole injection layer
114, 214: hole transport layer 13: organic light emitting layer
122, 222: red luminescent material layer 124, 224: green luminescent material layer
126, 226: blue light emitting material layer 134, 234: electron transporting layer
132: hole blocking layer 140, 240: second electrode
223: hole blocking material D: organic light emitting diode
100: organic light emitting display

Claims (10)

A first electrode disposed on the substrate on which the first and second pixel regions are defined, the first electrode and the second pixel region;
A hole transport layer located above the first electrode corresponding to the first and second pixel regions;
A first light emitting material layer located on the hole transporting layer corresponding to the first pixel region and including a host, a dopant, and a hole blocking material;
A second light emitting material layer positioned on the hole transporting layer of the second pixel region;
And an electron transport layer and a second electrode sequentially deposited on the second common light emission layer,
Wherein a HOMO value of the hole blocking material is smaller than a HOMO value of the host and the dopant and a LUMO value of the hole blocking material is larger than a LUMO value of the host and the dopant.
The method according to claim 1,
Wherein each of X ₁ , X ₂ and X ₃ is carbon or nitrogen, at least one of X ₁ , X ₂ and X ₃ is nitrogen, each of Ar ₁ , Ar ₂ and Ar ₃ is a Substituted or unsubstituted C ₆ to C ₆₀ aryl or substituted or unsubstituted C ₅ to C ₅₀ heteroaryl, and at least one of Ar ₁ , Ar ₂ and Ar ₃ is selected from dibenzofuran or carbazole Light emitting diode.

A first electrode disposed on the substrate on which the first and second pixel regions are defined, the first electrode and the second pixel region;
A hole transport layer located above the first electrode corresponding to the first and second pixel regions;
A first light emitting material layer disposed on the hole transporting layer and corresponding to the first pixel region and including a hole blocking material;
A second light emitting material layer positioned on the hole transporting layer of the second pixel region;
And an electron transport layer and a second electrode sequentially deposited on the second common light emission layer,
Wherein each of X ₁ , X ₂ and X ₃ is carbon or nitrogen, at least one of X ₁ , X ₂ and X ₃ is nitrogen, each of Ar ₁ , Ar ₂ and Ar ₃ is a Substituted or unsubstituted C ₆ to C ₆₀ aryl or substituted or unsubstituted C ₅ to C ₅₀ heteroaryl, and at least one of Ar ₁ , Ar ₂ and Ar ₃ is selected from dibenzofuran or carbazole Light emitting diode.

The method according to claim 2 or 3,
Wherein the hole blocking material is one of the following materials.

The method according to claim 1,
Wherein the HOMO value of the hole blocking material is -6.5 to -5.5 eV and the LUMO value of the hole blocking material is -3.0 to -2.0 eV.
The method according to claim 1 or 3,
Wherein the hole blocking material has a concentration gradient in the first light emitting material layer.
The method according to claim 1 or 3,
And the hole blocking material in the first light emitting material layer has a weight ratio of 5 to 10%.
Claims [1]
The organic light emitting diode according to any one of claims 1 to 3, wherein the organic light emitting diode is disposed on the substrate.
And a thin film transistor located between the substrate and the organic light emitting diode and connected to the organic light emitting diode.
9. The method of claim 8,
Wherein the hole blocking material has a concentration gradient in the first light emitting material layer.
9. The method of claim 8,
And the hole blocking material in the first light emitting material layer has a weight ratio of 5 to 10%.

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