KR20110043324A - Organic light emitting display device - Google Patents

Abstract

PURPOSE: An organic electroluminescent display device is provided to improve recombination between a hole and an electron in a light emitting layer by using a device to which a hole transport layer is applied for controlling the mobility of the hole. CONSTITUTION: A first electrode is located on a substrate. An organic light emitting layer is located on the first electrode. A second electrode is located on the organic light emitting layer. The organic light emitting layer includes hole transport layers(121b1,121b2). A hole transport control layer(121b3) is interposed between the hole transport layers. The hole transport control layer is adjacent to a hole injection layer included in the organic light emitting layer.

Description

Organic Light Emitting Display Device

The present invention relates to an organic light emitting display device.

The organic light emitting display device used in the organic light emitting display device is a self-light emitting device having a light emitting layer formed between two electrodes. In the organic light emitting display device, electrons and holes are injected into the light emitting layer from an electron injection electrode and a hole injection electrode, respectively, and an exciton in which the injected electrons and holes combine is excited. The device emits light when it falls from the ground state to the ground state.

An organic light emitting display device using an organic light emitting display device includes a top emission type, a bottom emission type, and a dual emission type according to a direction in which light is emitted. According to this, it is divided into passive matrix type and active matrix type.

When the scan signal, the data signal, and the power are supplied to the plurality of subpixels arranged in a matrix form, the organic light emitting display device may display an image by emitting light of the selected subpixel.

The subpixel includes a transistor unit including a switching transistor, a driving transistor, and a capacitor, and an organic light emitting diode including a first electrode connected to a driving transistor included in the transistor unit, an organic light emitting layer, and a second electrode. The organic light emitting layer includes a hole injection layer, a hole transport layer, a light emitting layer, an electron transport layer and an electron injection layer to help injection and movement of electrons and holes. By the way, the structure of the conventional organic light emitting layer has a problem that the life is reduced due to the imbalance between the holes and the electrons in the light emitting layer is required to improve it.

SUMMARY OF THE INVENTION The present invention for solving the above-mentioned problems of the background art is to provide an organic light emitting display device capable of balancing holes and electrons in the light emitting layer to increase recombination therebetween and improve lifespan.

The present invention as a problem solving means described above, the substrate; A first electrode on the substrate; An organic light emitting layer on the first electrode; And a second electrode on the organic light emitting layer, wherein the organic light emitting layer includes a hole transport layer having a hole transport control layer interposed therebetween.

The hole movement control layer may be located in the central region of the hole transport layer.

The hole movement control layer may be adjacent to the hole injection layer included in the organic light emitting layer.

The hole movement control layer may be adjacent to the light emitting layer included in the organic light emitting layer.

The hole transport control layer may be made of an organic-inorganic composite material and a hole transport material.

The organic-inorganic composite material and the hole transport material may be formed in the same ratio.

The hole movement adjusting layer may have a thickness of about 1 mm to 50 mm.

The hole transport layer may include a first hole transport layer adjacent to the hole injection layer included in the organic light emitting layer, a hole transport control layer, and a second hole transport layer adjacent to the light emitting layer included in the organic light emitting layer.

The organic light emitting layer includes a hole injection layer located on the first electrode, a hole transport control layer located on the hole injection layer, a light emitting layer located on the hole transport control layer, an electron transport layer located on the light emitting layer, and electrons. It may include an electron injection layer located on the transport layer.

The transistor may be disposed between the substrate and the first electrode and have a source electrode or a drain electrode connected to the first electrode.

The present invention has an effect of providing an organic light emitting display device that can increase the recombination between the hole and the electron in the light emitting layer and improve the life by using a device to which the hole transport layer that can control the hole mobility is applied. In addition, the device according to the present invention has the effect of improving the initial life extension characteristics to determine the afterimage of the life characteristics.

Hereinafter, with reference to the accompanying drawings, the specific content for the practice of the present invention will be described.

1 is a plan view of an organic light emitting display device according to an exemplary embodiment of the present invention, and FIG. 2 is a cross-sectional view of an I-II region shown in FIG. 1.

1 and 2, an organic light emitting display device according to an exemplary embodiment of the present invention includes a substrate 110 and a substrate in which a display area AA is defined by sub-pixels SP formed in a matrix form. It includes a sealing substrate 140 to protect the sub-pixels (SP) formed on the 110 from moisture or oxygen. The sub pixels SP are formed in a passive matrix type or an active matrix type. When the subpixels SP are formed in an active matrix type, the subpixels SP may be formed of a 2T (capacitor) structure including a switching transistor, a driving transistor, a capacitor, and an organic light emitting diode, or a structure in which a transistor and a capacitor are further added. It may be configured.

The substrate 110 and the encapsulation substrate 140 are bonded and sealed by the adhesive member 180 formed in the non-display area NA positioned outside the display area AA. However, the sealing substrate 140 may be sealed by a multi-protective film made of an organic, inorganic or organic-inorganic composite material. On the other hand, in the illustrated organic light emitting display device, the pad unit 170 is provided on the outside of the substrate 110 to receive various signals or power from the outside, and the substrate 110 is formed by the driving device 160 composed of one chip. It is an example that the elements formed on the) are driven. Although the driving device 160 is illustrated as having a structure including a data driver and a scan driver, the scan driver may be separately formed in the non-display area NA.

Hereinafter, the structure of the subpixel will be described in more detail.

3 is an exemplary cross-sectional view of the subpixel illustrated in FIG. 1, and FIG. 4 is a hierarchical view of the organic light emitting layer.

As shown in FIG. 3, the buffer layer 111 is positioned on the substrate 110. The buffer layer 111 may be formed to protect the thin film transistor formed in a subsequent process from impurities such as alkali ions flowing out of the substrate 110. The buffer layer 111 may be formed of silicon oxide (SiOx), silicon nitride (SiNx), or the like.

The gate 112 is positioned on the buffer layer 111. The gate 112 is selected from the group consisting of molybdenum (Mo), aluminum (Al), chromium (Cr), gold (Au), titanium (Ti), nickel (Ni), neodymium (Nd), and copper (Cu). It may be formed of a single layer or multiple layers of one or an alloy thereof.

The first insulating layer 113 is positioned on the gate electrode 112. The first insulating layer 113 may be, but is not limited to, a silicon oxide layer (SiOx), a silicon nitride layer (SiNx), or a multilayer thereof.

The active layer 114 is positioned on the first insulating layer 113. The active layer 114 may include amorphous silicon or polycrystalline silicon crystallized therefrom. Although not illustrated, the active layer 114 may include a channel region, a source region, and a drain region, and the source region and the drain region may be doped with P-type or N-type impurities. In addition, the active layer 114 may include an ohmic contact layer to lower the contact resistance.

The source electrode 115a and the drain electrode 115b are positioned on the active layer 114. The source electrode 115a and the drain electrode 115b may be formed of a single layer or multiple layers. When the source electrode 115a and the drain electrode 115b have a single layer, molybdenum (Mo), aluminum (Al), and chromium ( Cr), gold (Au), titanium (Ti), nickel (Ni), neodymium (Nd) and copper (Cu) may be made of any one or an alloy thereof. In contrast, when the source electrode 115a and the drain electrode 115b have multiple layers, a double layer of molybdenum / aluminum-neodymium, or a triple layer of molybdenum / aluminum / molybdenum or molybdenum / aluminum-neodymium / molybdenum may be used.

The second insulating layer 116 is positioned on the source electrode 115a and the drain electrode 115b. The second insulating layer 116 may be a silicon oxide layer (SiOx), a silicon nitride layer (SiNx), or a multilayer thereof, but is not limited thereto. The second insulating layer 116 may be a passivation layer.

The third insulating layer 117 is positioned on the second insulating layer 116. The third insulating layer 117 may be a silicon oxide layer (SiOx), a silicon nitride layer (SiNx), or multiple layers thereof, but is not limited thereto. The third insulating layer 117 may be a planarization layer.

The above is the description of the batam gate type driving transistor located on the substrate 110. Hereinafter, the organic light emitting diode on the driving transistor will be described.

The first electrode 119 is positioned on the third insulating layer 117. The first electrode 119 may be selected as an anode or a cathode. The first electrode 119 selected as the anode may be made of a transparent material such as indium tin oxide (ITO) or indium zinc oxide (IZO), but is not limited thereto.

The bank layer 120 having an opening exposing a part of the first electrode 119 is positioned on the first electrode 119. The bank layer 120 may include organic materials such as benzocyclobutene (BCB) -based resin, acrylic resin, or polyimide resin, but is not limited thereto.

The organic emission layer 121 is positioned in the opening of the bank layer 120. As illustrated in FIG. 4, the organic light emitting layer 121 includes a hole injection layer 121a, a hole transport layer 121b, a light emitting layer 121c, an electron transport layer 121d, and an electron injection layer 121e.

The hole injection layer 121a may play a role of smoothly injecting holes. CuPc (cupper phthalocyanine), PEDOT (poly (3,4) -ethylenedioxythiophene), PANI (polyaniline), and NPD (N, N-dinaphthyl) -N, N'-diphenyl benzidine) may be composed of any one or more selected from the group consisting of, but is not limited thereto.

The hole transport layer 121b serves to facilitate the transport of holes, NPD (or NPB) (N, N-dinaphthyl-N, N'-diphenyl benzidine), TPD (N, N'-bis- (3- methylphenyl) -N, N'-bis- (phenyl) -benzidine), s-TAD and MTDATA (4,4 ', 4 "-Tris (N-3-methylphenyl-N-phenyl-amino) -triphenylamine) The hole transport layer 121b may include a hole transport control layer, and the description of the hole transport layer 121b including the hole transport control layer will be described in more detail below. do.

The light emitting layer 121c includes a host and a dopant. The emission layer 121c may include a material emitting red, green, blue, and white light and may be formed using phosphorescent or fluorescent materials. When the light emitting layer 121c emits red, it includes a host material including CBP (carbazole biphenyl) or mCP (1,3-bis (carbazol-9-yl), and PIQIr (acac) (bis (1-phenylisoquinoline) acetylacetonate iridium), PQIr (acac) (bis (1-phenylquinoline) acetylacetonate iridium), PQIr (tris (1-phenylquinoline) iridium) and PtOEP (octaethylporphyrin platinum) It may be made of a phosphor material, otherwise it may be made of a fluorescent material including PBD: Eu (DBM) 3 (Phen) or Perylene, but is not limited thereto.When the light emitting layer 121c emits green, CBP or mCP It may include a host material comprising a, and a phosphor containing a dopant material including Ir (ppy) 3 (fac tris (2-phenylpyridine) iridium), alternatively, Alq3 (tris (8-hydroxyquinolino) aluminum) fluorescent material When the light emitting layer 121c emits blue, the light emitting layer 121c may include a host material including CBP or mCP, and may be formed of a phosphor including a dopant material including (4,6-F2ppy) 2Irpic. Alternatively, it may be composed of a fluorescent material including any one selected from the group consisting of spiro-DPVBi, spiro-6P, distilbenzene (DSB), distriarylene (DSA), PFO-based polymer and PPV-based polymer. But it is not limited thereto.

The electron transport layer 121d serves to facilitate the transport of electrons, and may be made of any one or more selected from the group consisting of Alq3 (tris (8-hydroxyquinolino) aluminum), PBD, TAZ, spiro-PBD, BAlq, and SAlq. However, the present invention is not limited thereto.

The electron injection layer 121e serves to facilitate the injection of electrons, and may be Alq3 (tris (8-hydroxyquinolino) aluminum), PBD, TAZ, LiF, spiro-PBD, BAlq or SAlq, but is not limited thereto. . An embodiment of the present invention is not limited to FIG. 4, and at least one of the hole injection layer 121a, the hole transport layer 121b, the electron transport layer 121d, and the electron injection layer 121e may be omitted.

The second electrode 122 is positioned on the organic emission layer 121. The second electrode 122 may be selected as a cathode or an anode. The second electrode 122 selected as the cathode may use aluminum (Al) or the like, but is not limited thereto.

Hereinafter, a hole transport layer according to an embodiment of the present invention will be described in more detail.

5 is a block diagram of a hole transport layer according to an embodiment of the present invention, Figure 6 is a lifetime graph of the comparative example and the embodiment.

As shown in Figure 5, the hole transport layer (121b1, 121b2) according to an embodiment of the present invention includes a hole movement control layer (121b3). The hole movement control layer 121b3 is located in the central region of the hole transport layers 121b1 and 121b2. In this case, the hole transport layers 121b1 and 121b2 are bisected into the first hole transport layer 121b1 and the second hole transport layer 121b1, and they are made of the same material. However, the first hole transport layer 121b1 and the second hole transport layer 121b1 may be formed of different materials in consideration of hole mobility.

The hole movement control layer 121b3 is formed of an organic-inorganic composite material 121ba and a hole transport material 121bb. The organic-inorganic composite material 121ba and the hole transport material 121bb may be mixed in the same ratio, but the ratio of the organic-inorganic composite material 121ba and the hole transport material 121bb is in the material constituting the organic light emitting layer 121. It may vary. The organic-inorganic composite material 121ba and the hole transport material 121bb may be formed by co-deposition, but are not limited thereto.

The hole movement control layer 121b3 configured as described above slightly reduces the movement characteristics of the holes H in the regions of the hole transport layers 121b1 and 121b2, thereby assisting recombination of holes and electrons in the emission layer 121c. It is possible to improve the life of the. In order to help the understanding of the description is added to the description of the experimental results of the embodiment compared to the comparative example as follows.

In an embodiment, the hole transport control layer 121b3 is applied to the hole transport layers 121b1 and 121b2 by applying Liq [8-Quinolinolato Lithium] and NPD (or NPB) as the organic-inorganic composite material 121ba and the hole transport material 121bb. Intervention results The following experimental results were obtained compared to the comparative example.

Table 1 shows the structure of the comparative example and the example. Structure of Comparative Example 1st electrode / hole injection layer / 1st hole transport layer / 2nd hole transport layer / light emitting layer / electron transport layer / electron injection layer / second electrode Structure of the Example 1st electrode / hole injection layer / 1st hole transport layer / hole transport control layer / 2nd hole transport layer / light emitting layer / electron transport layer / electron injection layer / second electrode

In the structure of Table 1, the embodiment was formed in the same structure as the comparative example except for the hole movement control layer interposed between the first hole transport layer and the second hole transport layer. In addition, the first hole transport layer and the second hole transport layer of Examples and Comparative Examples were formed of the same material.

Table 2 shows the voltage (V), light intensity (cd / A), current (Im / W), color coordinates (CIE_x, CIE_y) and quantum efficiency (EQE) measured in the structure of the comparative example and the example. rescue V cd / A Im / W CIE_x CIE_y EQE (%) Comparative example 3.9 6.6 5.2 0.134 0.125 7.0 Example 4.1 6.9 5.3 0.134 0.117 7.6

Table 2 shows measured values when the current-voltage-luminance (IVL) is 10 mA / cm 2.

As shown in Table 2 and Figure 6, the structure of the embodiment (Emb) slightly increased in the case of the driving voltage and efficiency compared to the comparative example (Ref), but it can be seen that the life (particularly the initial life) is significantly improved.

In the case of Liq constituting the hole movement control layer 121b3 of the embodiment, the HOMO level is -5.7 eV and the LUMO level is -3.15 eV, and in the case of NPD, the HOMO level is It has a characteristic of -5.5 eV and the LUMO level has -2.4 eV. Therefore, in the case of the holes injected through the hole injection layer 121a in the above experimental example, the mobility is slightly reduced because the low homo level of Liq forms a barrier while moving along the homo level of NPD. In general, since the mobility of holes is superior to the mobility of electrons, a balance between holes and electrons is very important in the emission layer 121c. On the other hand, the embodiment has found that the mobility of the holes can be slightly reduced to balance the holes and the electrons in the light emitting layer 121c, thereby improving the lifespan as described above.

In an embodiment, the thickness of the hole movement control layer 121b3 is formed in the range of 1Å ~ 50Å. When the thickness of the hole movement control layer 121b3 is formed to be 1 Å or more, the hole transport capacity is slightly reduced, so that the balance between holes and electrons in the light emitting layer 121c can be efficiently balanced. When the thickness of the hole movement control layer 121b3 is set to 50 μm or less, the hole transport capacity is slightly reduced within the range in which the device can be stably driven, thereby efficiently balancing the hole and the electron in the light emitting layer 121c. It becomes possible.

In the embodiment, Liq and NPD (or NPB) are applied as the organic-inorganic composite material 121ba and the hole transport material 121bb constituting the hole movement control layer 121b3. However, in the case of the organic-inorganic composite material 121ba, one of Znq2 [Bis (8-Quinolinolato) Zinc], Mgq2 [Bis (8-Quinolinolato) Magnesium] or a similar material may be selected. In the case of the hole transport material 121bb, a material that performs one or similar functions among TPD and MTDATA may be selected.

On the other hand, the hole movement control layer 121b3 may be formed between the hole transport layers 121b1 and 121b2 and the light emitting layer 121c, unlike the above-described embodiment. In addition, when the organic light emitting layer 121 includes a hole blocking layer for blocking the movement of holes, the hole movement adjusting layer 121b3 may be formed between the hole transport layers 121b1 and 121b2 and the hole blocking layer.

Hereinafter, a hole transport layer according to another embodiment of the present invention will be described.

7 to 10 is a block diagram of a hole transport layer according to another embodiment of the present invention.

7 and 8, the hole transport layers 121b1 and 121b2 according to the first embodiment of the present invention also include the hole movement control layer 121b3. The hole movement control layer 121b3 is composed of the organic-inorganic composite material 121ba and the hole transport material 121bb as described above in the embodiment of the present invention.

The hole movement control layer 121b3 is configured to be adjacent to the hole injection layer included in the organic light emitting layer as shown in FIG. 7 or to be adjacent to the light emitting layer included in the organic light emitting layer as shown in FIG. 8. In FIG. 7, the thickness of the second hole transport layer 121b2 is thicker than the thickness of the first hole transport layer 121b1 constituting the hole transport layers 121b1 and 121b2. 8, the thickness of the first hole transport layer 121b1 is thicker than the thickness of the second hole transport layer 121b2 constituting the hole transport layers 121b1 and 121b2.

9 and 10, the hole transport layers 121b1 and 121b2 according to the second embodiment of the present invention also include the hole movement control layer 121b3. The hole movement control layer 121b3 is composed of the organic-inorganic composite material 121ba and the hole transport material 121bb as described above in the embodiment of the present invention.

The hole movement control layer 121b3 is configured to contact the hole injection layer included in the organic light emitting layer as shown in FIG. 9 or to contact the light emitting layer included in the organic light emitting layer as shown in FIG. 10. In FIG. 9, instead of omitting the first hole transport layer 121b1 constituting the hole transport layers 121b1 and 121b2, the thickness of the second hole transport layer 121b2 is thicker. In contrast, in FIG. 10, instead of omitting the second hole transport layer 121b2 constituting the hole transport layers 121b1 and 121b2, the thickness of the first hole transport layer 121b1 is thicker.

The present invention has the effect of providing an organic light emitting display device which can increase the recombination between the holes and electrons in the light emitting layer and improve the life using the device to which the hole transport layer that can control the hole mobility is applied. In addition, the device according to the present invention has the effect of improving the initial life extension characteristics to determine the afterimage of the life characteristics.

While the present invention has been described in connection with what is presently considered to be practical exemplary embodiments thereof, it is to be understood that the invention is not limited to the disclosed embodiments, but, on the contrary, It will be understood that the invention may be practiced. Therefore, the embodiments described above are to be understood as illustrative and not restrictive in all aspects. In addition, the scope of the present invention is shown by the claims below, rather than the above detailed description. Also, it is to be construed that all changes or modifications derived from the meaning and scope of the claims and their equivalent concepts are included in the scope of the present invention.

1 is a plan view of an organic light emitting display device according to an embodiment of the present invention;

FIG. 2 is a cross-sectional view of the region I-II shown in FIG. 1. FIG.

3 is an exemplary cross-sectional view of the sub-pixel illustrated in FIG. 1.

4 is a hierarchical view of an organic light emitting layer.

5 is a block diagram of a hole transport layer according to an embodiment of the present invention.

6 is a life graph of the comparative example and the example.

7 to 10 is a block diagram of a hole transport layer according to another embodiment of the present invention.

<Explanation of symbols on main parts of the drawings>

110: substrate 140: sealing substrate

119: first electrode 121: organic light emitting layer

122: second electrode 121b: hole transport layer

121b1: first hole transport layer 121b2: second hole transport layer

121b3: hole transport control layer

Claims (10)

Board; A first electrode on the substrate; An organic light emitting layer on the first electrode; And A second electrode on the organic light emitting layer, The organic light emitting layer, An organic light emitting display device comprising a hole transport layer interposed with a hole transport control layer. The method of claim 1, The hole movement control layer, And an organic light emitting display device positioned in a central region of the hole transport layer. The method of claim 1, The hole movement control layer, And an adjacent hole injection layer included in the organic light emitting layer. The method of claim 1, The hole movement control layer, And an organic light emitting display device adjacent to the light emitting layer included in the organic light emitting layer. The method of claim 1, The hole movement control layer, An organic light emitting display device comprising an organic-inorganic composite material and a hole transport material. The method of claim 5, And the organic-inorganic composite material and the hole transport material have the same ratio. The method of claim 1, The thickness of the hole movement control layer, An organic light emitting display device, characterized in that 1 ~ 50 ~. The method of claim 1, The hole transport layer, An organic light emitting display device comprising: a first hole transport layer adjacent to a hole injection layer included in the organic light emitting layer, the hole movement control layer, and a second hole transport layer adjacent to a light emitting layer included in the organic light emitting layer. The method of claim 1, The organic light emitting layer, A hole injection layer on the first electrode; The hole movement adjusting layer positioned on the hole injection layer; A light emitting layer on the hole movement control layer; An electron transport layer on the light emitting layer; An organic light emitting display device comprising an electron injection layer on the electron transport layer. The method of claim 1, And a transistor unit disposed between the substrate and the first electrode and having a source electrode or a drain electrode connected to the first electrode.

Images