KR20090031146A - Organic light emitting device - Google Patents

Abstract

An organic light emitting device is provided to improve a driving voltage, light emitting efficiency, and luminance by adding dispersed inorganic material to a hole injection layer. An organic light emitting device comprises a substrate(100), a first electrode(110), organic functional layers(120), and a second electrode(130). The first electrode is positioned on the substrate. The organic functional layers are positioned on the first electrode, and include at least a light emitting layer(125). The second electrode is positioned on the organic functional layers. An organic functional layer adjacent to the second electrode among the organic functional layers includes dispersed inorganic material(128). The inorganic material includes metal compound. The metal compound is one or more selected in a group composed of LiQ, LiF, NaF, KF, RbF, CsF, FrF, BeF2, MgF2, CaF2, SrF2, BaF2, and RaF2.

Description

Organic Light Emitting Device

The present invention relates to an organic electroluminescent device, and more particularly, to an organic electroluminescent device in which inorganic substances are dispersed in an organic functional layer.

Recently, the importance of the flat panel display (FPD) has increased with the development of multimedia. In response, Liquid Crystal Display (LCD), Plasma Display Panel (PDP), Field Emission Display (FED), Organic Light Emitting Diode Display Device, etc. The same various displays are put to practical use.

Among them, the organic light emitting display device has a high response time with a response speed of 1 ms or less, low power consumption, and no self-emission, thus having no problem in viewing angle.

In a typical organic light emitting display device, a substrate, a first electrode is positioned on the substrate, and an organic layer including at least a light emitting layer is disposed on the first electrode. The second electrode is positioned on the organic layer. The organic layer may further include a hole injection layer (HIL), a hole transportation layer (HTL), an electron transport layer (ETL) and an electron injection layer (EIL). have.

The principle of operation of the organic light emitting device of this structure is as follows. When a voltage is applied between the first electrode and the second electrode, holes are injected from the first electrode and injected into the light emitting layer through the hole injection layer and the hole transport layer, and electrons are injected from the second electrode through the electron injection layer and the electron transport layer. It is injected into the light emitting layer. Holes and electrons injected into the emission layer recombine to form an exciton, and emit light by energy generated as the exciton transitions to the ground state.

For the high luminous efficiency of the organic light emitting device, the balance of holes and electrons injected into the light emitting layer should be well balanced. To this end, conventionally, a hole injection layer or a hole transport layer is formed between the first electrode and the light emitting layer, and an electron transport layer or an electron injection layer is formed between the light emitting layer and the second electrode to lower the energy barrier between the layers to move electrons and holes. Was made smooth.

However, in the conventional organic light emitting device, since the hole mobility is 10 times faster than the electron mobility, the amount of holes and electrons injected into the light emitting layer is changed. Therefore, there is a problem that the luminous efficiency of the organic light emitting device is lowered.

Accordingly, the present invention provides an organic light emitting device that can improve the luminous efficiency of the organic light emitting device.

In order to achieve the above object, an organic light emitting display device according to an embodiment of the present invention is a substrate, a first electrode positioned on the substrate, the organic functional layer positioned on the first electrode, at least including a light emitting layer For example, the second electrode positioned on the organic functional layers and the organic functional layer adjacent to the second electrode among the organic functional layers may include an inorganic material, and the inorganic material may be dispersed in the organic functional layer.

In addition, an organic light emitting display device according to an embodiment of the present invention is a substrate, a first electrode positioned on the substrate, the organic functional layers positioned on the first electrode, at least including a light emitting layer, the organic functional layer The second electrode positioned on the field and the organic functional layer adjacent to the first electrode of the organic functional layers may include an inorganic material, and the inorganic material may be dispersed in the organic functional layer.

The organic light emitting display device of the present invention has an advantage of improving the luminous efficiency of the organic light emitting display device.

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

<Example 1>

1 is a cross-sectional view illustrating an organic light emitting display device according to a first embodiment of the present invention.

Referring to FIG. 1, in the organic light emitting display device according to the first embodiment of the present invention, a first electrode 100, a first electrode 110 positioned on the first substrate 100, is positioned, and the first electrode ( The organic functional layers 120 including the hole injection layer 121, the hole transport layer 122, the light emitting layer 125, the electron transport layer 126, and the electron injection layer 127 positioned on the 110 are positioned. It may include a second electrode 130 positioned on the functional layers 120. The electron injection layer 127 adjacent to the second electrode 130 may further include an inorganic material 128 dispersed in the electron injection layer 127.

First, the first electrode 110 is positioned on the first substrate 100. At least one thin film transistor including a semiconductor layer, a gate electrode, a source electrode, and a drain electrode may be included between the first substrate 100 and the first electrode 110.

The first substrate 100 may be made of a material including insulating glass, plastic, or a conductive material.

The first electrode 110 may be an anode and may be a transparent electrode or a reflective electrode. When the first electrode 110 is a transparent electrode, the first electrode 110 may be any one of indium tin oxide (ITO), indium zinc oxide (IZO), or zinc oxide (ZnO). In addition, when the first electrode 110 is a reflective electrode, the first electrode 110 may be formed of aluminum (Al), silver (Ag), or nickel (Ni) under a layer made of any one of ITO, IZO, or ZnO. It may further include a reflective layer made of any one, and in addition, may include the reflective layer between two layers made of any one of ITO, IZO or ZnO.

The first electrode 110 may be formed using a sputtering method, an evaporation method, a vapor phase deposition method, or an electron beam deposition method.

Organic functional layers 120 are positioned on the first electrode 110. The organic functional layers 120 may include at least the light emitting layer 125. In addition, the organic functional layers 120 may further include any one or more selected from the group consisting of a hole injection layer 121, a hole transport layer 122, an electron transport layer 126, and an electron injection layer 127. .

 The hole injection layer 121 may play a role of smoothly injecting holes from the first electrode 110 to the light emitting layer 125, and may include CuPc (cupper phthalocyanine) and PEDOT (poly (3,4) -ethylenedioxythiophene). ), PANI (polyaniline) and NPD (N, N-dinaphthyl-N, N'-diphenyl benzidine) may be made of any one selected from the group consisting of, but not limited to.

The hole injection layer 121 may have a valence band level of -5.0 to -5.5 eV and a conducting band level of -1.8 to -2.8 eV to facilitate movement of holes to the light emitting layer. have.

The hole injection layer 121 may be formed using an evaporation method or a spin coating method.

The hole injection layer 121 may have a thickness of about 5 nm to about 150 nm. Here, when the thickness of the hole injection layer 121 is 5 nm or more, there is an advantage that the hole injection characteristics can be prevented from being lowered. There is an advantage that can be prevented from increasing the driving voltage to improve.

A buffer layer may be further included between the first electrode 110 and the hole injection layer 121. The buffer layer may include a compound including a hydroxyl group (-OH), a cyan group (-CN), or a halogen group having a strong electron affinity. For example, the buffer layer may include a compound having the following formula.

At least one of R1 to R6 may be a hydroxyl group (-OH), a cyan group (-CN) or a halogen group.

Since the buffer layer serves to stabilize the interface and includes a material having a strong electron affinity, the buffer layer attracts electrons present in the hole injection layer 121 into the buffer layer. Thus, a relatively large amount of holes are generated in the hole injection layer 121, these holes are transferred to the hole transport layer, the light emitting layer is supplied with a sufficient amount of holes. Therefore, the buffer layer has an effect of lowering the driving voltage by stabilizing the interface and generating holes in the hole injection layer.

The difference between the conduction band level and the valence band level of the buffer layer may be within ± 5 eV. Here, when the difference between the conduction band level and the valence band level of the buffer layer is -0.5 eV or more, hole trapping in which holes cannot move from the first electrode to the hole injection layer can be prevented from occurring.

The thickness of the buffer layer may be 10 to 100 kPa. If the thickness of the buffer layer is 10 GPa or more, the interface between the first electrode and the hole injection layer can be stabilized. If the thickness of the buffer layer is 100 GPa or less, holes can be easily moved from the first electrode to the hole injection layer.

The hole transport layer 122 serves to facilitate the transport of holes, NPD (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) It may be made of any one, but is not limited thereto.

The hole transport layer 122 may have a valence band level of -5.0 to -5.8 eV, and a conduction band level of -1.8 to -3.0 eV to facilitate movement of holes to the light emitting layer.

The hole transport layer 122 may be formed using an evaporation method or a spin coating method.

The hole transport layer 122 may have a thickness of about 5 nm to about 150 nm. In this case, when the thickness of the hole transport layer 122 is 5 nm or more, there is an advantage of preventing the hole transporting property from being lowered. When the thickness of the hole transport layer 122 is less than or equal to 150 nm, the thickness of the hole transport layer 122 is too thick to improve the movement of holes. In order to prevent the driving voltage from rising, there is an advantage.

The emission layer 125 may be formed of a material emitting red, green, and blue, and may be formed using phosphorescent or fluorescent materials.

When the light emitting layer 125 is 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, and, alternatively, may be made of a phosphor including PBD: Eu (DBM) ₃ (Phen) or perylene, but is not limited thereto.

In this case, in the case of the light emitting layer 125 emitting red, the valence band level of the host material may be -5.0 to -6.5 eV, and the conduction band level may be -2.0 to -3.5 eV. And, the valence band level of the dopant material may be -4.0 to -6.0 eV, and the conduction band level may be -2.4 to -3.5 eV. The conduction band level of the host material may comprise the conduction band level of the dopant material.

When the light emitting layer 125 is green, the light emitting layer 125 may include a host material including CBP or mCP, and may be formed of a phosphor including a dopant material including Ir (ppy) 3 (fac tris (2-phenylpyridine) iridium). And, alternatively, it may be made of a fluorescent material including Alq3 (tris (8-hydroxyquinolino) aluminum), but is not limited thereto.

In this case, in the case of the light emitting layer 125 emitting green, the valence band level of the host material may be -5.0 to -6.5 eV, and the conduction band level may be -2.0 to -3.5 eV. And, the valence band level of the dopant material may be -4.5 to -6.0 eV, and the conduction band level may be -2.0 to -3.5 eV. The conduction band level of the host material may comprise the conduction band level of the dopant material.

When the light emitting layer 125 is blue, the phosphor may include a host material including CBP or mCP and a dopant material including (4,6-F ₂ ppy) ₂ Irpic. , spiro-DPVBi, spiro-6P, distilbenzene (DSB), distriarylene (DSA), PFO-based polymer and PPV-based polymer may be composed of a fluorescent material including any one selected from the group consisting of, but not limited to Do not.

In this case, in the case of the light emitting layer 125 emitting blue light, the valence band level of the host material may be -5.0 to -6.5 eV, and the conduction band level may be -2.0 to -3.5 eV. And, the valence band level of the dopant material may be -4.5 to -6.0 eV, and the conduction band level may be -2.0 to -3.5 eV. The conduction band level of the host material may comprise the conduction band level of the dopant material.

The electron transport layer 126 serves to facilitate the transport of electrons, and may be made of any one selected from the group consisting of Alq3 (tris (8-hydroxyquinolino) aluminum), PBD, TAZ, spiro-PBD, BAlq, and SAlq. It is not limited to this.

The electron transport layer 126 may have a valence band level of -5.0 to -6.5 eV, and a conduction band level of -2.5 to -3.8 eV to facilitate movement of electrons to the light emitting layer.

The electron transport layer 126 may be formed using an evaporation method or a spin coating method.

The electron transport layer 126 may have a thickness of about 1 nm to about 50 nm. Here, when the thickness of the electron transporting layer 126 is 1 nm or more, there is an advantage of preventing the electron transporting property from decreasing. When the thickness of the electron transporting layer 126 is 50 nm or less, the thickness of the electron transporting layer 126 is too thick to improve the movement of electrons. In order to prevent the driving voltage from rising, there is an advantage.

The electron injection layer 127 serves to facilitate the injection of electrons, and may be Alq3 (tris (8-hydroxyquinolino) aluminum), PBD, TAZ, spiro-PBD, BAlq or SAlq, but is not limited thereto.

The electron injection layer 127 may further include an inorganic material 128, and the inorganic material 128 may further include a metal compound. The metal compound may include an alkali metal or an alkaline earth metal. The metal compound containing the alkali metal or alkaline earth metal is LiF, NaF, KF, RbF, CsF, FrF, BeF ₂ , MgF ₂ , CaF ₂ , SrF ₂ , BaF ₂ And RaF ₂ may be any one or more selected from the group consisting of, but is not limited thereto.

The electron injection layer 127 may have a valence band level of −5.0 to −6.5 eV, and a conduction band level of −2.5 to −3.5 eV to facilitate movement of electrons to the emission layer. Here, the highest valence band level of the electron injection layer 127 may be lower than or equal to the highest valence band level of the electron transport layer 126, and the lowest level of conduction band of the electron injection layer 127 is the electron transport layer 126. Can be lower than or equal to the lowest level of conduction band.

On the contrary, when the electron transport layer 126 is not formed, the valence band maximum level of the electron injection layer 127 may be lower than or equal to the peak level of the emission layer 125. The conduction band minimum level may be lower than or equal to the conduction band minimum level of the light emitting layer 125.

Further, the highest valence band of the electron injection layer 127 may be higher than or equal to the highest valence band of the second electrode, that is, the cathode electrode, and the lowest conductive band of the electron injection layer 127 is the valence band of the cathode electrode. It can be higher than the highest level.

The inorganic material 128 may have a conduction band level and a valence band level of -2.0 to -4.0 eV.

Here, the highest valence band level of the inorganic material 128 may be higher than the highest valence band level of the organic functional layer including the inorganic material. In addition, the valence band maximum level of the inorganic material 128 may be higher than the valence band maximum level of the remaining organic functional layers except for the organic functional layer including the inorganic material 128 among the organic functional layers.

The electron injection layer 127 may have a thickness of about 1 nm to about 50 nm. In this case, when the thickness of the electron injection layer 127 is 1 nm or more, there is an advantage that the electron injection characteristics may be prevented from being lowered. There is an advantage that the driving voltage can be prevented from rising.

Here, in the embodiment of the present invention, the thickness of the electron injection layer 127 including an inorganic material may be any one of organic functional layers other than the electron injection layer 127, that is, the hole injection layer 121 and the hole transport layer 122. It may be thinner than the light emitting layer 125 or the electron transport layer 126.

That is, since the hole injected from the first electrode 110 has a mobility 10 times faster than the electron injected from the second electrode 130, when the thickness of the electron injection layer 127 is thinner than other layers, the second Since the electron injected from the electrode 130 has a small thickness of the electron injection layer 127, the electrons can move quickly, so that the hole and the charge can be balanced. Therefore, the formation of excitons in the light emitting layer 125 may be uniform, thereby improving luminous efficiency.

As described above, in the first embodiment of the present invention, the electron injection layer 127 may include an inorganic material 128, and the inorganic material 128 may be dispersed in the electron injection layer 127. .

The electron injection layer 127 may form an organic material and an inorganic material constituting the electron injection layer by a co-deposition method. In this case, the mixing ratio of the organic material and the inorganic material may be 2: 1 to 10: 1. Here, when the mixing ratio of the organic material and the inorganic material is 2: 1 or more, the mobility of electrons injected into the light emitting layer from the second electrode can be improved, and when the mixing ratio of the organic material and the inorganic material is 10: 1 or less, the inorganic material in the electron injection layer Since the ratio of is reduced, it is possible to prevent the problem that the mobility of electrons is difficult to be improved.

The inorganic material 128 in the electron injection layer 127 may be uniformly dispersed, and the spacing between the particles of the inorganic material 128 dispersed in the electron injection layer 127 may be 5 to 45 mm 3. Here, when the interval between the particles of the inorganic material 128 is 5 Å or more, it is possible to prevent the inorganic material from acting as a barrier, that is, an insulating film, in the passage through which the electrons move, to hinder the movement of the electrons, and between the particles of the inorganic material 128. If the interval of is 45 kHz or less, there is an advantage that the hopping of the electrons can be prevented from becoming difficult.

In addition, the electron injection layer 127 including the inorganic material 128 may serve to lower the conduction band level of the organic material forming the electron injection layer 127 of the valence band level of the inorganic material 128.

Therefore, the inorganic material 128 in the electron injection layer 127 facilitates hopping of electrons injected from the second electrode to the light emitting layer, thereby improving the light emission efficiency by balancing holes and electrons injected into the light emitting layer. There is an advantage to that.

The second electrode 130 may be a cathode electrode, and may be made of magnesium (Mg), calcium (Ca), aluminum (Al), silver (Ag), or an alloy thereof having a low work function. Here, the second electrode 130 may be formed to a thickness thin enough to transmit light when the organic light emitting device is a front or double-side light emitting structure, and when the organic light emitting device is a bottom light emitting structure, It can be formed thick enough to reflect.

In the first embodiment of the present invention, the electron transport layer 126 and the electron injection layer 127 are formed between the light emitting layer 125 and the second electrode 130 as an example, the light emitting layer 125, the electron transport layer 126 ) And the organic light emitting diode in which the inorganic material 128 is dispersed in the electron injection layer 127 closest to the second electrode 130 among the electron injection layer 127 has been described.

On the contrary, when the electron injection layer is not interposed between the light emitting layer and the second electrode, the inorganic material may be dispersed in the electron transport layer, which is an organic functional layer adjacent to the second electrode.

2 is a conceptual view illustrating the operation of the organic light emitting display device according to the first embodiment of the present invention, the left and right direction shows the position of the stacking direction of the organic light emitting device and the up and down direction is the conduction band and the valence band of each layer material. Energy level is indicated.

Referring to FIG. 2, the first electrode 110, the light emitting layer 125, the electron injection layer 127, and the second electrode 130 are positioned. The Fermi level 110a is shown in the first electrode 110, and the lowest level 125a of the conduction band and the highest level 125b of the valence band are shown in the light emitting layer 125. In the electron injection layer 127, the lowest level of conduction band 127a and the highest level of valence band 127b are shown, and the Fermi level 130a of the second electrode 130a is shown.

Since the conduction band minimum level 125a of the emission layer 125 is higher than the conduction band minimum level 127a of the electron injection layer 127, the electrons injected from the second electrode 130 move in the direction of the emission layer 125. It must cross the gap 125c. Also, since the valence band highest level 127b of the electron injection layer 127 is lower than the valence band maximum level 125b of the emission layer 125, holes injected from the first electrode 110 are directed toward the electron injection layer 127. In order to move to, the energy bandgap 127c must be exceeded.

An organic light emitting display device according to an embodiment of the present invention is an inorganic material having a valence band peak level 128a higher than the valence band peak level 127b of the organic functional layer adjacent to the second electrode, that is, the electron injection layer 127. It is included to facilitate the movement of electrons.

That is, by mixing the inorganic material having the valence band highest level 128a higher than the valence band highest level 127b of the electron injection layer 127 and lower than the conduction band minimum level 127a, the valence band maximum level 128a of the inorganic material is mixed. The high conduction band minimum level 127a of the electron injection layer 127 can be lowered to facilitate hopping of electrons.

In addition, the valence band highest level 128a of the inorganic material may be higher than the valence band maximum level 125b of the emission layer 125 and lower than the conduction band minimum level 125a. Here, the valence band highest level 128a of the inorganic material may be lower than the conduction band minimum level of the host material of the emission layer 125 and may be higher than the valence band maximum level. In addition, the valence band peak level 128a of the inorganic material may be lower than the conduction band minimum level of the dopant material of the light emitting layer 125 and may be higher than or equal to the valence band peak level.

Also, although not shown in FIG. 2, when the electron transport layer is interposed between the light emitting layer 125 and the electron injection layer 127, the valence band peak level 128a of the inorganic material is higher than the valence band peak level of the electron transport layer and is a conduction band. It may be lower than the lowest level.

Hereinafter, in the second embodiment of the present invention described below, unlike the first embodiment, an organic light emitting diode in which the inorganic material 128 is included in the hole injection layer 121 closest to the first electrode will be described. . The description of the first electrode, the hole transport layer, the light emitting layer, the electron transport layer, and the electron injection layer, which overlap with the first embodiment, will be omitted.

3 is a cross-sectional view of an organic light emitting display device according to a second embodiment of the present invention.

Referring to FIG. 3, in the organic light emitting display device according to the second embodiment of the present invention, a first electrode 100, a first electrode 110 positioned on the first substrate 100, is positioned, and the first electrode ( The organic functional layers 120 including the hole injection layer 121, the hole transport layer 122, the light emitting layer 125, the electron transport layer 126, and the electron injection layer 127 positioned on the 110 are positioned. It may include a second electrode 130 positioned on the functional layers 120. The hole injection layer 121 adjacent to the first electrode 110 may further include a dispersed inorganic material 128.

The hole injection layer 121 of the organic light emitting diode according to the second embodiment of the present invention is CuPc (cupper phthalocyanine), PEDOT (poly (3,4) -ethylenedioxythiophene), PANI (polyaniline) and NPD (N, N- dinaphthyl-N, N'-diphenyl benzidine) may be any one selected from the group consisting of, but is not limited thereto.

The hole injection layer 121 may further include an inorganic material 128, and the inorganic material 128 may further include a metal compound. The metal compound may include an alkali metal or an alkaline earth metal. The metal compound containing the alkali metal or alkaline earth metal is LiF, NaF, KF, RbF, CsF, FrF, BeF ₂ , MgF ₂ , CaF ₂ , SrF ₂ , BaF ₂ And RaF ₂ may be any one or more selected from the group consisting of, but is not limited thereto.

The hole injection layer 121 may have a valence band level of 5.0 to 5.5 eV, and a conduction band level of 1.8 to 2.8 eV to facilitate movement of holes to the emission layer. Here, the highest valence band level of the hole injection layer 121 may be higher than or equal to the highest valence band level of the hole transport layer 122, and the lowest level of conduction band of the hole injection layer 121 may be defined as that of the hole transport layer 122. It may be higher than or equal to the lowest level of the conduction band.

In contrast, when the hole transport layer 122 is not formed, the valence band highest level of the hole injection layer 121 may be higher than or equal to the highest level of the valence band of the emission layer 125, and the hole injection layer 121 may be formed. The conduction band minimum level may be higher than or equal to the conduction band minimum level of the light emitting layer 125.

Also, the highest valence band of the hole injection layer 121 may be lower than or equal to the highest valence band of the first electrode, that is, the anode electrode, and the lowest conductive band of the hole injection layer 121 is the valence band of the anode electrode. It can be higher than the highest level.

The inorganic material 128 may have a valence band level and a conduction band level of 2.0 to 4.0 eV.

The hole injection layer 121 may have a thickness of about 1 nm to about 50 nm. Here, when the thickness of the hole injection layer 121 is 1 nm or more, there is an advantage that the hole injection characteristics can be prevented from deteriorating. When the thickness of the hole injection layer is 50 nm or less, the thickness of the hole injection layer is too thick to improve the movement of holes. There is an advantage that the driving voltage can be prevented from rising.

Here, in the embodiment of the present invention, the thickness of the hole injection layer 121 including an inorganic material may be any one of organic functional layers other than the hole injection layer 121, that is, the hole transport layer 122, the light emitting layer 125, and the electron. It may be thicker than the transport layer 126 or the electron injection layer 127.

That is, since the hole injected from the first electrode has a mobility 10 times faster than the electron injected from the second electrode, when the thickness of the hole injection layer is thicker than other layers, the hole injected from the first electrode is the hole injection layer. Since the thickness of is large, the mobility of holes can be reduced, so that the balance between the holes and the charges can be balanced. Therefore, it is possible to improve the luminous efficiency by making excitons uniform in the light emitting layer.

As described above, in the second embodiment of the present invention, the hole injection layer 121 may further include an inorganic material 128, and the inorganic material 128 may be dispersed in the hole injection layer 121. .

The interval between the particles of the inorganic material 128 dispersed in the hole injection layer 121 may be 5 to 45 kPa. Here, when the distance between the particles of the inorganic material 128 is 5 Å or more, it is possible to prevent the inorganic material from acting as a barrier, that is, an insulating film in the passage through which the holes move, so that the mobility of the holes is too low, and the particles of the inorganic material 128 If the spacing between the holes is 45 kPa or less, the mobility of the holes is so high that it is possible to prevent a problem that it is difficult to balance the holes and electrons bonded in the light emitting layer.

The hole injection layer 121 may form an organic material and an inorganic material constituting the hole injection layer by a co-deposition method. In this case, the mixing ratio of the organic material and the inorganic material may be 2: 1 to 10: 1. Here, when the mixing ratio of organic material and inorganic material is 2: 1 or more, the mobility of holes injected from the first electrode into the light emitting layer can be lowered to balance the holes and electrons bonded in the light emitting layer, and the mixing ratio of organic material and inorganic material is 10. When the ratio is less than or equal to 1, the ratio of the inorganic material in the hole injection layer is reduced, thereby making it difficult to lower the mobility of the holes, thereby preventing the problem of hardly balancing the holes and electrons bonded in the light emitting layer.

The valence band peak level of the inorganic material 128 may be higher than the valence band peak level of the organic functional layer including the inorganic material. In addition, the valence band maximum level of the inorganic material 128 may be higher than the valence band maximum level of the remaining organic functional layers except for the organic functional layer including the inorganic material 128 among the organic functional layers.

Here, the hole injection layer 121 including the inorganic material 128 may serve to lower the valence band level of the organic material of the inorganic material 128 forming the hole injection layer 121.

Accordingly, the inorganic material 128 in the hole injection layer 121 may reduce the mobility of holes injected from the first electrode to the light emitting layer, thereby improving luminous efficiency by balancing holes and electrons injected into the light emitting layer. .

4 is a conceptual diagram for explaining the operation of the organic light emitting display device according to the second embodiment of the present invention, the left and right direction shows the position of the stacking direction of the organic light emitting device and the up and down direction is the conduction band and valence band of each layer material Energy level is indicated.

Referring to FIG. 4, the first electrode 110, the hole injection layer 121, the light emitting layer 125, and the second electrode 130 are positioned. The Fermi level 110a is illustrated in the first electrode 110, and the lowest level of conduction band 121a and the highest valence band 121b are illustrated in the hole injection layer 121. In the light emitting layer 125, the lowest level of conduction band 125a and the highest level of valence band 125b are shown, and the Fermi level 130a of the second electrode 130a is shown.

Since the lowest conduction band level 125a of the emission layer 125 is lower than the lowest conduction band level 121a of the hole injection layer 121, electrons injected from the second electrode 130 move in the direction of the first electrode 110. The energy band gap 121c must be exceeded. In addition, since the highest valence band 121b of the hole injection layer 121 is higher than the highest valence band 125b of the emission layer 125, holes injected from the first electrode 110 move toward the emission layer 125. In order to do so, the energy bandgap 125c must be exceeded.

An organic light emitting display device according to an embodiment of the present invention is an inorganic material having a valence band peak level 128a higher than the valence band peak level 121b of the organic functional layer adjacent to the first electrode, that is, the hole injection layer 121. To reduce hole mobility.

That is, by mixing the inorganic material having the valence band highest level 128a higher than the valence band highest level 121b of the hole injection layer 121 and lower than the conduction band minimum level 121a, the valence band maximum level 128a of the inorganic material is mixed. The high conduction band minimum level 121a of the hole injection layer 121 can be lowered to reduce the mobility of holes.

In addition, the valence band highest level 128a of the inorganic material may be higher than the valence band maximum level 125b of the emission layer 125 and lower than the conduction band minimum level 125a. Here, the valence band highest level 128a of the inorganic material may be lower than the conduction band minimum level of the host material of the emission layer 125 and may be higher than the valence band maximum level. In addition, the valence band peak level 128a of the inorganic material may be lower than the conduction band minimum level of the dopant material of the light emitting layer 125 and may be higher than or equal to the valence band peak level.

In addition, although not shown in FIG. 4, when the hole transport layer is interposed between the light emitting layer 125 and the hole injection layer 121, the valence band maximum level 128a of the inorganic material is higher than the valence band maximum level of the hole transport layer and is conducted. It may be lower than the lowest level.

In the second exemplary embodiment of the present invention, the hole transport layer 122 and the hole injection layer 121 are formed between the light emitting layer 125 and the first electrode 110. For example, the light emitting layer 125 and the hole transport layer 122 may be used. ) And the organic light emitting diode in which the inorganic material 128 is dispersed in the hole injection layer 121 closest to the first electrode 110 of the hole injection layer 121 has been described.

Alternatively, when the hole injection layer is not formed between the light emitting layer and the first electrode, the inorganic material may be dispersed in the electron transport layer, which is an organic functional layer adjacent to the first electrode.

Hereinafter, unlike the above-described embodiments, an active matrix organic light emitting diode including a thin film transistor on a substrate will be described.

5 is a cross-sectional view of an organic light emitting display device according to a third embodiment of the present invention.

Referring to FIG. 5, a buffer layer 205 is positioned on a substrate 200. The buffer layer 205 is formed to protect the thin film transistor formed in a subsequent process from impurities such as alkali ions flowing out of the substrate 200, and is selectively selected using silicon oxide (SiO ₂ ), silicon nitride (SiNx), or the like. It may be formed as, but is not limited thereto.

The semiconductor layer 210 is positioned on the buffer layer 205. The semiconductor layer 210 may include amorphous silicon or polycrystalline silicon obtained by crystallizing the same. Although not illustrated, the semiconductor layer 210 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.

The gate insulating layer 215 is positioned on the substrate 200 including the semiconductor layer 210. The gate insulating layer 215 may be selectively formed using silicon oxide (SiO ₂ ), silicon nitride (SiNx), or the like.

The gate electrode 220 is positioned on a gate insulating layer 215 corresponding to a predetermined region of the semiconductor layer 210, that is, a channel region. The gate electrode 220 includes aluminum (Al), aluminum alloy (Al alloy), titanium (Ti), silver (Ag), molybdenum (Mo), molybdenum alloy (Mo alloy), tungsten (W), tungsten silicide (WSi _2). ) May include any one or more of the above.

An interlayer insulating layer 225 is disposed on the substrate 200 including the gate electrode 220. The interlayer insulating film 225 may be an organic film or an inorganic film, or may be a composite film thereof. have. When the interlayer insulating layer 225 is an inorganic layer, the interlayer insulating layer 225 may include silicon oxide (SiO ₂ ), silicon nitride (SiNx), or SOG (silicate on glass). It may include (benzocyclobutene, BCB) resin, but is not limited thereto.

Contact holes 230a and 230b may be disposed to penetrate the interlayer insulating layer 225 and the gate insulating layer 215 to expose a portion of the semiconductor layer 210.

The source electrode 235a and the drain electrode 235b electrically connected to the semiconductor layer 210 through the contact holes 230a and 230b are positioned on the substrate 200 including the contact holes 230a and 230b. do. The source and drain electrodes 235a and 235b may include a low resistance material to reduce wiring resistance, and may include a multilayer film made of molybdenum tungsten (MoW), titanium (Ti), aluminum (Al), or an aluminum alloy (Al alloy). Can be. In this case, a multilayer structure of titanium / aluminum / titanium (Ti / Al / Ti), molybdenum / aluminum / molybdenum (Mo / Al / Mo) or molybdenum tungsten / aluminum / molly tungsten (MoW / Al / MoW) may be used. Can be.

The planarization layer 240 is positioned on the source electrode 235a and the drain electrode 235b. The planarization layer 240 may include organic materials such as benzocyclobutene (BCB) -based resin, acrylic resin, or polyimide resin, but is not limited thereto.

The first electrode 250 is electrically connected to the drain electrode 235b through the via hole 245 formed in the planarization layer 240. The first electrode 250 may be an anode and may include a transparent conductive layer such as indium tin oxide (ITO) or indium zinc oxide (IZO). Alternatively, the first electrode 250 may have a stacked structure further including a reflective film under the transparent conductive layer, such as ITO / Ag / ITO or ITO / Ag.

The bank layer 255 exposing a portion of the first electrode 250 is disposed on the substrate 200 on which the first electrode 250 is formed. The bank layer 250 may include an organic material such as benzocyclobutene (BCB) -based resin, acrylic resin, or polyimide resin, but is not limited thereto.

The organic functional layer 260 is positioned on the first electrode 250 exposed by the bank layer 255. The organic functional layer 260 may be formed of an organic material, and the organic functional layer 260 may include at least a light emitting layer, and may further include an electron injection layer, an electron transport layer, a hole transport layer, or a hole injection layer on or below the light emitting layer. have.

The organic functional layer 260 may include an inorganic material in the electron injection layer as in the first embodiment described above. Alternatively, the organic functional layer 260 may include an inorganic material in the hole injection layer as in the second embodiment. .

Since the description of the organic functional layer 260 has been described with the above-described embodiments, a detailed description thereof will be omitted.

The second electrode 270 is positioned on the substrate 200 including the organic functional layer 260. The second electrode 270 may be a cathode for supplying electrons to the organic functional layer 260, and may include magnesium (Mg), silver (Ag), calcium (Ca), aluminum (Al), or an alloy thereof. Can be.

Hereinafter, an experimental example according to an organic light emitting display device according to an embodiment of the present invention. However, the following experimental examples are only preferable experimental examples of the present invention, and the present invention is not limited by the following experimental examples.

Experimental Example 1

Indium tin oxide (ITO) was formed as a first electrode on a substrate to a thickness of 130 nm, and NPD (4,4'-bis [N- (1-naphthyl) -N-phenyl was formed as a hole injection layer on the first electrode. -amino] biphenyl) was formed to a thickness of 40 nm, and NPD (4,4'-bis [N- (1-naphthyl) -N-phenyl-amino] biphenyl) was formed to a thickness of 30 nm as the hole transport layer. Blue light emitting layer by mixing a concentration of 2 wt% perylene (Perylene) with a dopant in DPVBi (4,4'-bis (2,2'-diphenyl vinyl) -1,1'-biphenyl) as a host on the hole transport layer Was formed to a thickness of 25nm, Alq ₃ (8-hydroxyquinoline aluminum) was formed to a thickness of 20nm as the electron transport layer. Next, Alq ₃ (8-hydroxyquinoline aluminum) and LiF were co-deposited at a ratio of 4: 1 to form an electron injection layer having a thickness of 10 nm. Subsequently, an Al film was formed to a thickness of 150 nm with a second electrode, and an Al film was formed to a thickness of 1000 kPa on the MgAg film.

Comparative Example 1

Except that the electron injection layer was formed of Alq ₃ (8-hydroxyquinoline aluminum) was formed in the same manner as the process conditions of Experimental Example 1.

Experimental Example 2

Experimental Example 1 except that the red light emitting layer was formed to a thickness of 25 nm by mixing a concentration of 2 wt% of the host CBP (carbazole biphenyl) dopant PIQIr (acac) (bis (1-phenylisoquinoline) acetylacetonate iridium) It was formed in the same manner as the process conditions.

Comparative Example 2

Except that the electron injection layer was formed of Alq ₃ (8-hydroxyquinoline aluminum) was formed under the same process conditions as in Experimental Example 2.

Experimental Example 3

Experimental Example 1 except that a green light emitting layer was formed to a thickness of 25 nm by mixing a concentration of 2 wt% of a dopant Ir (ppy) 3 (fac tris (2-phenylpyridine) iridium) with a host CBP (carbazole biphenyl). It formed similarly to process conditions of.

Comparative Example 3

Except that the electron injection layer was formed of Alq ₃ (8-hydroxyquinoline aluminum) was formed under the same process conditions as in Experimental Example 3.

The driving voltage, luminous efficiency and luminance of the organic light emitting diodes manufactured according to Experimental Examples 1,2 and 3 and Comparative Examples 1,2 and 3 were measured, and the results are shown in Table 1.

Experimental Example 1 Comparative Example 1 Experimental Example 2 Comparative Example 2 Experimental Example 3 Comparative Example 3 Driving voltage (V) 5.5 6.9 5.4 7.7 5.4 7.0 Luminous Efficiency (cd / A) 5.2 2.0 17.8 16.3 33.3 24.2 Luminance (lm / w) 3.0 1.3 9.4 6.7 19.4 10.8

As shown in Table 1, the organic light emitting display device according to an embodiment of the present invention includes LiF, that is, inorganic material 128 dispersed in the electron injection layer, and includes an electron injection layer made of a conventional organic material 128. Compared to one organic light emitting device, it can be seen that the driving voltage, luminous efficiency and luminance are further improved.

That is, by including the inorganic material dispersed in the electron injection layer, it is possible to improve the efficiency of the organic electroluminescent device by maintaining the charge balance between the hole and the electron by improving the mobility of the electron.

Hereinafter, unlike Experimental Examples 1, 2 and 3 described above, an organic electric field including an inorganic material in a hole injection layer, which is an organic functional layer adjacent to the first electrode, among the organic functional layers interposed between the first electrode and the light emitting layer. Experimental examples of the light emitting device will be described.

Experimental Example 4

Indium tin oxide (ITO) was formed as a first electrode on a substrate to a thickness of 130 nm, and NPD (4,4'-bis [N- (1-naphthyl) -N-phenyl was formed as a hole injection layer on the first electrode. -amino] biphenyl) and LiF were co-deposited at a ratio of 4: 1 to form a thickness of 40 nm, and as the hole transport layer, NPD (4,4'-bis [N- (1-naphthyl) -N-phenyl-amino ] biphenyl) was formed to a thickness of 30 nm. Blue light emitting layer by mixing a concentration of 2 wt% perylene (Perylene) with a dopant in DPVBi (4,4'-bis (2,2'-diphenyl vinyl) -1,1'-biphenyl) as a host on the hole transport layer Was formed to a thickness of 25nm, Alq ₃ (8-hydroxyquinoline aluminum) was formed to a thickness of 20nm as the electron transport layer. Next, Alq ₃ (8-hydroxyquinoline aluminum) was deposited to form an electron injection layer having a thickness of 10 nm. Subsequently, an Al film was formed to a thickness of 150 nm with a second electrode, and an Al film was formed to a thickness of 1000 kPa on the MgAg film.

<Comparative Example 4>

The hole injection layer was formed in the same manner as in Experimental Example 4, except that the hole injection layer was formed of NPD (4,4'-bis [N- (1-naphthyl) -N-phenyl-amino] biphenyl).

Experimental Example 5

Experimental Example 4 except that a red light emitting layer was formed to a thickness of 25 nm by mixing a concentration of 2 wt% of the host CBP (carbazole biphenyl) dopant PIQIr (acac) (bis (1-phenylisoquinoline) acetylacetonate iridium) It was formed in the same manner as the process conditions.

Comparative Example 5

The hole injection layer was formed in the same manner as in Experimental Example 5, except that the hole injection layer was formed of NPD (4,4'-bis [N- (1-naphthyl) -N-phenyl-amino] biphenyl).

Experimental Example 6

Experimental Example 5 except that the green light emitting layer was formed to a thickness of 25 nm by mixing a concentration of 2 wt% of the dopant Ir (ppy) 3 (fac tris (2-phenylpyridine) iridium) with the host CBP (carbazole biphenyl). It formed similarly to process conditions of.

Comparative Example 6

The hole injection layer was formed under the same process conditions as in Experiment 6, except that the hole injection layer was formed of NPD (4,4'-bis [N- (1-naphthyl) -N-phenyl-amino] biphenyl).

The driving voltage, luminous efficiency and luminance of the organic light emitting diodes manufactured according to Experimental Examples 4,5,6 and Comparative Examples 4,5,6 were measured, and the results are shown in Table 2.

Experimental Example 4 Comparative Example 4 Experimental Example 5 Comparative Example 5 Experimental Example 6 Comparative Example 6 Driving voltage (V) 5.4 7.1 5.5 7.8 5.5 7.2 Luminous Efficiency (cd / A) 5.0 2.1 16.5 15.8 31.0 22.1 Luminance (lm / w) 2.9 1.4 8.9 6.1 20.4 12.8

As shown in Table 2, the organic light emitting display device according to an embodiment of the present invention includes LiF dispersed in the hole injection layer, that is, an inorganic material, to the organic light emitting device having a hole injection layer made of a conventional organic material In comparison, it can be seen that the driving voltage, luminous efficiency and luminance are further improved.

That is, by including the inorganic material dispersed in the hole injection layer, by reducing the mobility of the hole it is possible to maintain the charge balance between the hole and the electron to increase the luminous efficiency of the organic light emitting device.

As described above, the organic light emitting display device according to an embodiment of the present invention, a hole injection layer or an electron injection layer adjacent to the first electrode or the second electrode of the organic functional layer interposed between the first electrode and the second electrode By including the inorganic material dispersed in, there is an advantage that can improve the driving voltage, luminous efficiency and brightness of the organic light emitting device.

Although the embodiments of the present invention have been described above with reference to the accompanying drawings, the above-described technical configuration of the present invention may be embodied in other specific forms by those skilled in the art to which the present invention pertains without changing its technical spirit or essential features. It will be appreciated that it 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 cross-sectional view of an organic light emitting display device according to a first embodiment of the present invention.

2 is a conceptual view showing the operation of the organic light emitting display device according to the first embodiment of the present invention.

3 is a cross-sectional view of an organic light emitting display device according to a second exemplary embodiment of the present invention.

4 is a conceptual diagram showing the operation of the organic light emitting display device according to the second embodiment of the present invention.

5 is a cross-sectional view of an organic light emitting display device according to a third exemplary embodiment of the present invention.

Claims (24)

Board; A first electrode on the substrate; Organic functional layers on the first electrode and including at least a light emitting layer; A second electrode on the organic functional layers; And Among the organic functional layers, the organic functional layer adjacent to the second electrode includes an inorganic material, The inorganic material is an organic light emitting device dispersed in the organic functional layer. The method of claim 1, The inorganic material is an organic electroluminescent device comprising a metal compound. The method of claim 2, The metal compound is an organic electroluminescent device comprising an alkali metal or alkaline earth metal. The method of claim 3, wherein The metal compound containing the alkali metal or alkaline earth metal is LiQ, LiF, NaF, KF, RbF, CsF, FrF, BeF ₂ , MgF ₂ , CaF ₂ , SrF ₂ , BaF ₂ And RaF _{2 The} organic electroluminescent device which is at least one selected from the group consisting of. The method of claim 1, And an organic functional layer adjacent to the second electrode is an electron injection layer or an electron transport layer. The method of claim 1, The organic light emitting device further comprises a hole transport layer or a hole injection layer between the first electrode and the light emitting layer. The method of claim 1, The organic functional layer of the organic functional layer including the inorganic material is thinner than any one of the organic functional layers except for the organic functional layer containing the inorganic of the organic functional layers. The method of claim 1, The valence band highest level of the inorganic material is higher than the valence band maximum level of the organic functional layer including the inorganic material. The method of claim 1, The valence band highest level of the inorganic material is higher than the valence band highest level of the remaining organic functional layers except for the organic functional layer including the inorganic material among the organic functional layers. The method of claim 1, The highest valence band level of the inorganic material is higher than the highest valence band level of the light emitting layer and lower than the lowest level of conduction band of the light emitting layer. The method of claim 1, And a thin film transistor including a semiconductor layer, a gate electrode, a source electrode, and a drain electrode on the substrate. The method of claim 1, An organic light emitting display device having an interval of 5 to 45 microns between the inorganic particles. Board; A first electrode on the substrate; Organic functional layers on the first electrode and including at least a light emitting layer; A second electrode on the organic functional layers; And The organic functional layer adjacent to the first electrode of the organic functional layers includes an inorganic material, The inorganic material is an organic light emitting device dispersed in the organic functional layer. The method of claim 13, The inorganic material is an organic electroluminescent device comprising a metal compound. The method of claim 14, The metal compound is an organic electroluminescent device comprising an alkali metal or alkaline earth metal. The method of claim 15, The metal compound containing the alkali metal or alkaline earth metal is LiQ, LiF, NaF, KF, RbF, CsF, FrF, BeF ₂ , MgF ₂ , CaF ₂ , SrF ₂ , BaF ₂ And RaF _{2 The} organic electroluminescent device which is at least one selected from the group consisting of. The method of claim 13, And an organic functional layer adjacent to the first electrode is a hole injection layer or a hole transport layer. The method of claim 13, The organic light emitting device further comprises an electron transport layer or an electron injection layer between the second electrode and the light emitting layer. The method of claim 13, The thickness of the organic functional layer containing the inorganic material is thicker than any one of the organic functional layers except for the organic functional layer containing the inorganic of the organic functional layer. The method of claim 13, The valence band highest level of the inorganic material is higher than the valence band maximum level of the organic functional layer including the inorganic material. The method of claim 13, The valence band highest level of the inorganic material is higher than the valence band maximum level of the remaining organic functional layers except for the inorganic material among the organic functional layers. The method of claim 13, The highest valence band level of the inorganic material is higher than the highest valence band level of the light emitting layer and lower than the lowest level of conduction band of the light emitting layer. The method of claim 13, And a thin film transistor including a semiconductor layer, a gate electrode, a source electrode, and a drain electrode on the substrate. The method of claim 13, An organic light emitting display device having an interval of 5 to 45 microns between the inorganic particles.

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