KR20150075674A - Organic light emitting device - Google Patents

Abstract

The present invention relates to an organic light emitting device. The organic light emitting device comprises: an anode; a cathode facing the anode; and an organic layer including a light emitting layer formed between the anode and the cathode. The organic layer comprises a first electron transport layer and a mixed layer between the light emitting layer and the cathode.

Description

ORGANIC LIGHT EMITTING DEVICE

The present disclosure relates to an organic light emitting device.

The organic light emission phenomenon is one example in which current is converted into visible light by an internal process of a specific organic molecule. The principle of organic luminescence phenomenon is as follows. When an organic layer is positioned between the anode and the cathode, a voltage is applied between the inside of the specific organic molecule through the two electrodes, electrons and holes are injected into the organic layer from the cathode and the anode, respectively. Electrons and holes injected into the organic material layer recombine to form an exciton, and the exciton falls back to the ground state to emit light. An organic light emitting device using such a principle may generally include an organic material layer including an anode, a cathode, and an organic material layer disposed therebetween, for example, a hole injecting layer, a hole transporting layer, a light emitting layer, and an electron transporting layer.

The organic light emitting device refers to a self-emitting type device using an electroluminescent phenomenon that emits light when a current flows through a light emitting organic compound, and has been attracting attention as a next generation material in various industrial fields such as display and illumination.

It is necessary to develop a technique for lowering the driving voltage of the organic light emitting device to improve the light emitting efficiency of the organic light emitting device.

Korean public disclosure: 10-2007-0076521

The present invention provides an organic light emitting device having a novel structure.

One embodiment of the present disclosure includes an anode; A cathode opposite to the anode; And an organic layer including an emitting layer provided between the anode and the cathode, wherein the organic layer includes a first electron transporting layer and a mixed layer between the emitting layer and the cathode, and the first electron transporting layer and the mixed layer Wherein the mixed layer comprises at least one hole transporting material and at least one electron transporting material, and the first electron transporting layer is doped with an n-type dopant.

In addition, one embodiment of the present disclosure relates to an anode; A cathode opposite to the anode; Wherein each of the light emitting units includes an organic layer including a light emitting layer, and at least one organic layer of the light emitting unit includes a light emitting layer and a light emitting layer, And a first electron transport layer and a mixed layer between the cathodes, wherein the first electron transport layer and the mixed layer are in contact with each other, and the mixed layer includes at least one hole transport material and at least one electron transport material, And the transport layer is doped with an n-type dopant.

In addition, one embodiment of the present invention provides a display including the organic light emitting element.

In addition, one embodiment of the present invention provides a lighting apparatus including the organic light emitting element.

The organic light emitting device according to one embodiment of the present invention has an advantage of low driving voltage. Specifically, the organic light emitting device according to one embodiment of the present invention has a wide density of states (DOS) generated in the mixed layer, which facilitates injection of electrons into the electron injection layer, have.

In addition, the organic light emitting device according to one embodiment of the present invention is advantageous in terms of quantum efficiency (QE).

1 and 2 show an example of a laminated structure of an organic light emitting diode according to an embodiment of the present invention.
FIGS. 3 and 4 show an example of a light emitting unit of an organic light emitting diode according to an embodiment of the present invention.
FIG. 5 illustrates electron transfer between a mixed layer and a first electron transport layer in an organic light emitting device according to one embodiment of the present invention.
Fig. 6 shows the electron movement in the case where the mixed layer is not provided and in the case where the mixed layer is provided.
FIG. 7 shows an example of the difference in energy level between the hole transporting material and the electron transporting material forming the bandgap and charge transfer complex of the charge transfer complex in the mixed layer.

Hereinafter, the present invention will be described in more detail.

One embodiment of the present disclosure includes an anode; A cathode opposite to the anode; And an organic layer including a light emitting layer provided between the anode and the cathode,

Wherein the organic material layer includes a first electron transporting layer and a mixed layer between the light emitting layer and the cathode,

Wherein the first electron transporting layer and the mixed layer are provided in contact with each other,

Wherein the mixed layer comprises at least one hole transporting material and at least one electron transporting material,

And the first electron transporting layer is doped with an n-type dopant.

In addition, one embodiment of the present disclosure relates to an anode; A cathode opposite to the anode; A cathode, and at least two light emitting units provided between the anode and the cathode,

Wherein each of the light emitting units includes an organic layer including a light emitting layer,

At least one organic layer of the light emitting unit includes a first electron transporting layer and a mixed layer between the light emitting layer and the cathode,

Wherein the first electron transporting layer and the mixed layer are provided in contact with each other,

Wherein the mixed layer comprises at least one hole transporting material and at least one electron transporting material,

And the first electron transporting layer is doped with an n-type dopant.

The first electron transporting layer and the mixed layer are provided in contact with each other, which means that the first electron transporting layer and the mixed layer are physically in contact with each other.

The light-emitting unit includes at least one light-emitting layer, and the light-emitting layer in the light-emitting unit corresponds to the light-emitting region as a point where electrons transported from the cathode and holes transported from the anode meet together to form an exciton. Further, the light emitting unit may further include an additional layer in addition to the light emitting layer.

According to an embodiment of the present invention, the mixed layer may be provided between the light emitting layer and the first electron transporting layer.

According to an embodiment of the present invention, the organic layer may further include a second electron transport layer provided between the light emitting layer and the mixed layer.

The second electron transport layer may not be doped with an n-type dopant, but may be a layer made of an electron transporting material. That is, the second electron transporting layer may be made of a single material.

1 and 2 show an example of a laminated structure of an organic light emitting diode according to an embodiment of the present invention.

Specifically, the organic luminescent device of FIG. 1 includes a structure in which a hole transport layer 201, a light emitting layer 301, a mixed layer 401, a first electron transport layer 501, and a cathode 601 are sequentially stacked on the anode 101 Respectively. The mixed layer 401 and the first electron transport layer 501 of FIG. 1 are provided in contact with each other, and the organic light emitting device according to one embodiment of the present invention is not limited to the structure of FIG. 1, It is also possible.

2 includes a hole transporting layer 201, a light emitting layer 301, a second electron transporting layer 701, a mixed layer 401, a first electron transporting layer 501, and a cathode (not shown) on the anode 101. [ 601 are sequentially stacked. The mixed layer 401 and the first electron transport layer 501 of FIG. 2 are in contact with each other, and the organic light emitting device according to one embodiment of the present disclosure is not limited to the structure of FIG. 2, It is also possible.

FIGS. 3 and 4 show an example of a light emitting unit of an organic light emitting diode according to an embodiment of the present invention.

3 shows that the mixed layer 401 and the first electron transporting layer 501 are provided on the light emitting layer 301. The mixed layer 401 and the first electron transporting layer 501 ) Are in contact with each other. In addition, the light emitting unit of the organic light emitting diode according to one embodiment of the present invention is not limited to the structure of FIG. 3, but may include a further layer.

4 shows that the second electron transport layer 701, the mixed layer 401 and the first electron transport layer 501 are provided on the light emitting layer 301. The mixed layer 401 is formed on the light emitting layer 301, And the first electron transport layer 501 are in contact with each other. In addition, the light emitting unit of the organic light emitting diode according to one embodiment of the present invention is not limited to the structure of FIG. 4, but may include a further layer.

The light emitting layer may serve to facilitate electron transfer between the first electron transporting layer doped with the n-type dopant and the light emitting layer and / or the second electron transporting layer.

The mixed layer may have a high density of state (DOS) in the mixed layer due to the mixing of the different materials of the electron transporting material and the hole transporting material, so that the electrons of the first electron transporting layer may form a state density (DOS) of the mixed layer. Density of State "). Specifically, electrons move smoothly from the light emitting layer to the first electron transporting layer along the density (State of Density) of the mixed layer (DOS), thereby increasing the efficiency of the organic light emitting device.

FIG. 5 illustrates electron transfer between a mixed layer and a first electron transport layer in an organic light emitting device according to one embodiment of the present invention. In FIG. 5, ETL (Electron Transporting Layer) refers to an electron transporting layer, and n-ETL refers to a first electron transporting layer doped with an n-type dopant. In addition, E _F means the Fermi level. Referring to FIG. 5, it can be seen that the first electron transport layer is doped with an n-type dopant, and the Fermi level (E _F ) is moved close to the LUMO energy level.

When an electron transport layer doped with an n-type dopant and an electron transport layer made of a single material are provided in contact with each other, an electron injection barrier exists between the two layers. Specifically, in the electron transport layer doped with the n-type dopant, the Fermi level (E _F ) is moved close to the LUMO energy level, and since the electron transport layer made of a single material has inherent weak n-type characteristics, The level is moderately or weakly biased to the LUMO energy level. Since electron injection between the respective layers is performed according to the density of state (DOS) of each layer, the difference in state density level between the electron transport layer doped with the n-type dopant and the electron transport layer made of a single material The electron injection barrier by the electron injection barrier does not smoothly inject electrons.

On the contrary, the organic light emitting device according to one embodiment of the present invention includes the mixed layer between the electron transporting layer doped with the n-type dopant and the electron transporting layer made of the single material, so that the electron transport from the n-type doped electron transporting layer is smooth . Further, the electron transport to the electron transport layer made of a single material in the mixed layer can be smoothly performed.

Fig. 6 shows the electron movement in the case where the mixed layer is not provided and in the case where the mixed layer is provided. Specifically, FIG. 6A shows an electron injection barrier between an electron transport layer doped with an n-type dopant and an electron transport layer made of a single material without a mixed layer. 6 (b) shows that the electron transport from the electron transport layer doped with the n-type dopant is smoothly provided by the mixed layer.

Referring to FIG. 6, it can be seen that electrons can move smoothly from the electron transport layer doped with the n-type dopant by the mixed layer having a wide state density in the organic light emitting device according to one embodiment of the present invention.

As described above, when an electron transport layer doped with an n-type dopant and an electron transport layer made of a single material are provided in contact with each other, an electron injection barrier between the two layers is generated to increase the driving voltage of the organic light emitting element , The efficiency is lowered.

In order to solve this problem, it is possible to solve the electron injection barrier problem of each layer by contacting an electron transport layer doped with an n-type dopant and an electron transport layer doped with a metal compound such as LiF or Liq. However, in such a case, the n-type characteristics of the electron transporting layer are deteriorated. In addition, the metal oxide included in the electron transport layer causes quenching of the luminescent layer, thereby reducing the efficiency of the organic luminescent device. Furthermore, since the metal oxide is often decomposed during vacuum thermal deposition or deforming molecules, the stability of the organic light emitting device may be deteriorated.

On the contrary, according to the organic light emitting device according to one embodiment of the present invention, the electron injection barrier generated at the interface of the first electron transporting layer due to the mixed layer can be removed. Further, the efficiency and stability of the organic light emitting device due to the use of the mixed layer are not affected. Further, the recombination region of excitons can be controlled by adjusting the mixing ratio of the electron transporting material and the hole transporting material of the mixed layer.

According to one embodiment of the present invention, the electron transporting material contained in the mixed layer may be the same as the electron transporting material forming the electron transporting layer of the organic light emitting device.

According to an embodiment of the present invention, the hole transporting material contained in the mixed layer may be the same as the hole transporting material forming the hole transporting layer of the organic light emitting device.

According to one embodiment of the present invention, the mixed layer can recycle the triplet excitons generated in the light emitting layer by using a charge transfer complex generated in the mixed layer, thereby increasing the efficiency of the organic light emitting device. Therefore, the mixed layer may be provided adjacent to the light emitting layer of the organic light emitting device.

According to one embodiment of the present invention, the light emitting position of the organic light emitting device is broadly distributed in a gaussian form, and a recombination zone may be distributed to a part of the mixed layer adjacent to the light emitting layer. In this case, since the spin state of the excitons in the charge transport complex of the hole transport material and the electron transport material in the mixed layer can be changed, triplet excitons discarded in the light emitting layer can be utilized. Further, when the triplet excitons generated in the light emitting layer move to the adjacent mixed layer and energy transfer is performed to the charge transfer complex, triplet excitons which are also discarded in the light emitting layer by changing the spin states of the excitons are also utilized It is possible.

According to one embodiment of the present invention, the material contained in the light emitting layer may be determined according to the energy level of the charge transfer complex generated in the mixed layer. Specifically, according to one embodiment of the present disclosure, when the energy of the charge transfer complex of the mixed layer is 2.5 eV, the energy of the light emitting material contained in the light emitting layer may have an energy exceeding 2.5 eV. More specifically, according to one embodiment of the present disclosure, when the light emitting layer comprises a blue light emitting material, the energy of the charge transfer complex of the mixed layer may be at least 2.7 eV.

The energy of the charge transfer complex may mean the energy level of the charge transfer complex, and the energy of the light emitting material may be a singlet state energy level of the light emitting material.

According to an embodiment of the present invention, the organic layer may further include a hole transporting layer, and the mixed layer may be provided between the hole transporting layer and the light emitting layer. Specifically, when the electron mobility of the light emitting layer is greater than the hole mobility, the recombination zone has a higher probability of occurring at the interface between the light emitting layer and the hole transporting layer, so that the mixed layer is provided between the light emitting layer and the hole transporting layer, The anti-exciton can be recycled.

According to an embodiment of the present invention, the mixed layer may be provided between the first electron transporting layer and the light emitting layer. Specifically, when the hole mobility of the light emitting layer is greater than the electron mobility, the recombination zone has a higher probability of occurring at the interface between the light emitting layer and the first electron transporting layer, so that the mixed layer is provided between the light emitting layer and the first electron transporting layer Whereby the triplet exciton of the light emitting layer can be recycled.

According to one embodiment of the present invention, the mixed layer may be a layer including one or more hole transporting materials and two or more electron transporting materials.

According to one embodiment of the present invention, the mixed layer may be a layer in which a hole transporting material and an electron transporting material are mixed. Specifically, the mixed layer may be a single layer in which the hole transporting material and the electron transporting material are not bonded to each other.

According to one embodiment of the present disclosure, the mixed layer may include a charge transfer complex of a hole transporting material and an electron transporting material. Specifically, according to one embodiment of the present invention, the mixed layer may be formed of a combination of a hole transporting material and an electron transporting material forming a charge transporting complex. Furthermore, according to one embodiment of the present disclosure, the mixed layer comprises the charge transfer complex; The remaining hole transport material without forming a charge transfer complex; And an electron transporting material.

According to one embodiment of the present disclosure, when the charge transport complex is mixed with the hole transporting material and the electron transporting material, a charge transfer complex may be formed between the two materials.

According to one embodiment of the present invention, in order to form the charge transport complex by mixing a hole transport material and an electron transport material, an electron transport material having an electron acceptor property in a hole transport material having an electron donating property in an excited state The complex between the two materials must be formed. Therefore, according to one embodiment of the present invention, the hole transporting material of the mixed layer has a strong electron donating property, and the electron transporting material has a strong electron accepting property.

According to an embodiment of the present invention, the hole transporting material and the electron transporting material of the mixed layer are combined to cause charge transfer between the two materials, so that the two materials can be coupled to each other by electrostatic attraction.

The charge transfer complex in the present specification may mean a state in which electrons and holes are distributed in two different materials.

According to one embodiment of the present disclosure, the charge transfer complex of the mixed layer produces a new energy level generated by the charge transfer complex in addition to the energy levels of the hole transport material and electron transport material forming the charge transfer complex.

Specifically, the charge-transporting complex has a property of binding electrons and positive holes with respect to excited states and excitons formed in the respective hole transporting materials and electron transporting materials in the charge transporting complex due to the binding properties of electrons and holes. The distance becomes farther away. That is, electrons and holes in the excited state of the charge transfer complex become weaker than electrons and holes in the exciton state generated in the respective hole transporting materials and electron transporting materials.

Therefore, the charge transfer complex lowers the exchange energy between electrons and holes, thus reducing the difference between singlet energy and triplet energy levels. As a result, when a charge transport complex is formed by a combination of a hole transport material and an electron transport material, a material having a small difference in singlet energy and triplet energy can be produced. Specifically, according to one embodiment of the present disclosure, the charge transfer complex can create a state in which the difference between singlet energy and triplet energy level is small. According to one embodiment of the present disclosure, the difference between singlet energy and triplet energy may be 0.3 eV or less.

The inventors of the present invention have found that triplet excitons generated by electron-hole recombination are the most important factor for inhibiting the efficiency in an organic light emitting device using fluorescent light emission utilizing only singlet excitons. In this case, the singlet exciton produced by recombination was only about 25%.

Accordingly, the present inventors have developed an organic light emitting device including the mixed layer of the present specification. That is, the organic light emitting device according to one embodiment of the present invention can solve the above-described problems and achieve higher efficiency. In particular, when a material having a small difference between singlet energy and triplet energy is used as the charge transfer complex, triplet excitons discarded in the organic light emitting device using fluorescence can be utilized and the efficiency can be further increased.

Specifically, the organic light emitting device according to one embodiment of the present invention forms a charge transfer complex through a combination of an electron transporting material and a hole transporting material, and utilizes a small singlet-triplet energy difference of the charge transfer complex to form an electron And the triplet exciton among the excitons generated through the recombination of the holes can be recycled, thereby realizing the improvement of the efficiency of the organic light emitting device.

The recombination of electrons and holes in the light emitting layer of the organic light emitting diode according to one embodiment of the present invention can be largely divided into two methods.

First, according to one embodiment of the present invention, electrons and holes in a light emitting layer recombine in a host material to form an exciton, and then light can be emitted through energy transfer to a dopant material . More specifically, when the light emitting layer is constituted by a host-guest system, holes and electrons are injected at the HOMO energy level and the LUMO energy level of the host material, respectively, and recombine with the Langevin type, The excitons are first generated in the material, and the excitons are sequentially formed in the dopant material through the energy transfer, and finally, the light can be emitted from the dopant material. According to an embodiment of the present invention, the light emission may be an organic light emitting device including a fluorescent light emitting layer.

Second, according to one embodiment of the present invention, electrons and holes are directly injected into the dopant material, and excitons are formed directly in the dopant material to emit light. Specifically, light emission may occur in a form similar to that of the SRH type (Shockley-Read-Hall type). According to one embodiment of the present invention, the light emission may be an organic light emitting device including a phosphorescent light emitting layer.

According to one embodiment of the present invention, when the light emitting layer is formed of a combination of a host material and a dopant material, the host material may serve to transfer excitons to the dopant without participating in actual light emission. Therefore, the host material may have a higher energy level than the dopant material. Thus, according to one embodiment of the present disclosure, host materials that emit energy in a range overlapping the energy absorption range of the dopant material may be used for more efficient energy transfer.

According to one embodiment of the present invention, when the recombination of electrons and holes in the light emitting layer occurs by the recombination of the Langevin type and the light emission occurs through the energy transfer from the host material to the dopant material, The excitons of the host material produced by the recombination of the light emitting material may have an energy higher than the energy of the dopant at which light emission takes place. At this time, not only the singlet exciton energy level of the host material but also the exciton energy level of the triplet may be higher than the energy level of the dopant material.

Further, according to one embodiment of the present invention, in the case of an organic light emitting device including a fluorescent light emitting layer, excitons used for light emission are singlet excitons of the host material, and triplet excitons of the host material may not contribute to light emission have. The triplet excitons of the host material have a long lifetime and can diffuse in the light emitting layer and react with each other (triplet-triplet annihilation) to form singlet excitons and can be used again for light emission. In addition, the triplet exciton of the host material may be extinguished by releasing heat along the vibronic level and may be extinguished after energy transfer to the triplet of dopant material. That is, the triplet exciton of the host material does not contribute to luminescence.

The triplet excitons of the host material may diffuse to adjacent layers. Therefore, according to one embodiment of the present invention, the efficiency of the organic light emitting device can be increased by recycling the triplet excitons of the host material diffused into the mixed layer provided adjacent to the light emitting layer. Specifically, the charge transfer complex in the mixed layer can convert the triplet excitons discarded in the light emitting layer into singlet excitons, and transmit the generated singlet excitons to the light emitting layer, thereby improving the light emitting efficiency. According to an embodiment of the present invention, when the light emitting layer of the organic light emitting device is a fluorescent light emitting layer, the luminous efficiency can be improved more.

According to one embodiment of the present disclosure, the energy level of triplet excitons of the host material is greater than or equal to the singlet energy level of the dopant, greater than or equal to the energy level of the charge transfer complex in the mixed layer, The energy level of the triplet exciton of the material and the electron transporting material may be smaller than that of the triplet exciton.

According to one embodiment of the present invention, the mass ratio of the hole transporting material and the electron transporting material in the mixed layer may be 1: 4 to 4: 1.

Specifically, when a mixed layer is formed using a hole transporting material and an electron transporting material within the above range, the utilization of the triplet exciton generated in the light emitting layer can be maximized. In addition, when the charge transfer complex is formed within the above range, the charge transfer complex can be maximally formed, thereby increasing the efficiency of the organic light emitting device.

According to one embodiment of the present invention, since the mixed layer includes the hole transporting material, the electron transporting material, and the charge transfer complex thereof, both the electron and the hole can be moved. Further, the mobility of electrons and holes can be controlled by adjusting the mixing ratio of the hole transporting material and the electron transporting material. That is, the charge balance in the light emitting layer can be controlled by controlling the mobility of electrons and holes.

Furthermore, according to one embodiment of the present invention, the density of state of the mixed layer may be more widely distributed than that of the hole transporting material and the electron transporting material alone. That is, the energy level at which the hole or electron can move may have the energy level of each of the hole transporting material and the electron transporting material, and the DOS of each of the hole transporting material and the electron transporting material may be intact .

According to an embodiment of the present disclosure, energy transfer may occur between the hole transporting material and the electron transporting material in the mixed layer, and energy transfer between the hole transporting material and / or the electron transporting material and the charge transporting complex This may happen.

According to one embodiment of the present invention, when the hole transporting material and the electron transporting material of the mixed layer form a charge transfer complex, the maximum energy that the charge transporting complex can have depends on the HOMO energy level of the hole transporting material, The LUMO energy level of the transport material may be different. In this case, the electrons are present in the LUMO of the electron transporting material, and the holes may be in a state of being weakly bound to each other while being present in the HOMO of the hole transporting material. Therefore, the band gap of the charge transfer complex becomes smaller than that of the hole transporting material or electron transporting material alone, which forms the charge transfer complex. Further, since the electrons and holes of the charge transfer complex are bound and stabilized by coulombic attraction, the band gap of the charge transfer complex is different from the HOMO energy level of the hole transporting material to the LUMO energy level of the electron transporting material Lt; / RTI >

FIG. 7 shows an example of the difference in energy level between the hole transporting material and the electron transporting material forming the bandgap and charge transfer complex of the charge transfer complex in the mixed layer.

According to one embodiment of the present invention, the binding energy between holes of the hole transporting material and electrons of the electron transporting material may be 0.2 eV or less when forming the charge transfer complex.

According to an embodiment of the present invention, the difference between the HOMO energy level of the hole transporting material and the electron transporting material of the mixed layer may be 0.2 eV or more. Specifically, the difference in the HOMO energy level may be 0.3 eV or more.

According to an embodiment of the present invention, the LUMO energy level difference between the hole transporting material and the electron transporting material of the mixed layer may be 0.2 eV or more. Specifically, the difference in the LUMO energy level may be 0.3 eV or more.

According to an embodiment of the present invention, the HOMO energy level difference between the hole transporting material and the electron transporting material of the mixed layer may be 0.2 eV or more, and the LUMO energy level difference may be 0.2 eV or more. Specifically, the difference in the HOMO energy level may be 0.3 eV or more, and the LUMO energy level difference may be 0.3 eV or more.

According to one embodiment of the present invention, the difference between the LUMO energy level of the electron transporting material of the mixed layer and the HOMO energy level of the hole transporting material may be 2 eV or more. Specifically, the difference between the LUMO energy level of the electron transporting material of the mixed layer and the HOMO energy level of the hole transporting material may be 2.6 eV or more.

According to one embodiment of the present invention, the difference between the ionization potential of the hole transporting material of the mixed layer and the electron transporting material may be 0.2 eV or more. Specifically, the difference between the ionization potential of the hole transporting material and the electron transporting material of the mixed layer may be 0.3 eV or more.

According to an embodiment of the present invention, the difference in electron affinity between the hole transporting material of the mixed layer and the electron transporting material may be 0.2 eV or more. Specifically, the difference in electron affinity between the hole transporting material and the electron transporting material in the mixed layer may be 0.3 eV or more.

According to an embodiment of the present invention, the difference in ionization potential between the hole transport material and the electron transport material in the mixed layer is 0.2 eV or more, and the difference in electron affinity between the hole transport material and the electron transport material in the mixed layer is 0.2 eV. Specifically, the difference between the ionization potentials of the hole transport material and the electron transport material in the mixed layer is 0.3 eV or more, and the difference in electron affinity between the hole transport material and the electron transport material in the mixed layer may be 0.3 eV or more.

According to one embodiment of the present invention, the difference between the electron affinity of the electron transport material of the mixed layer and the ionization potential of the hole transport material may be 2 eV or more. Specifically, the difference between the electron affinity of the electron transport material of the mixed layer and the ionization potential of the hole transport material may be 2.6 eV or more.

According to one embodiment of the present invention, the HOMO energy level difference between the hole transporting material and the electron transporting material of the mixed layer, the difference in the LUMO energy level, and the difference between the LUMO energy level of the electron transporting material and the HOMO energy level of the hole transporting material The binding energy of the excitons in the mixed layer may be greater than the exciton binding energy of the hole transporting material or the electron transporting material. That is, the hole transporting material and the electron transporting material can be smoothly formed as a charge transporting complex.

According to an embodiment of the present invention, the difference in ionization potential between the hole transport material and the electron transport material in the mixed layer, the difference in electron affinity, and the difference between the electron affinity of the electron transport material and the ionization potential of the hole transport material In the above range, the binding energy of the excitons in the mixed layer may be greater than the exciton binding energy of the hole transporting material or the electron transporting material. That is, in the case of the above range, the hole transporting material and the electron transporting material can be smoothly formed as the charge transporting complex.

Specifically, the binding energy of the excitons generated in the charge transfer complex of the mixed layer is smaller than the exciton binding energy of the hole transporting material or the electron transporting material in the mixed layer. This is because, in the case of charge transfer complexes, holes and electrons are farther apart than excitons produced in a single material. Therefore, the range for the difference of the energy levels in the present specification is such that the excitons generated in the hole transporting material and the electron transporting material in the mixed layer have a minimum energy for overcoming the binding energy of the excitons to be transferred to the charge transporting complex The energy level to be obtained may be a difference.

According to one embodiment of the present invention, the charge transfer complex can be produced by directly recombining holes in the hole transport material and electrons in the electron transport material. Specifically, when the range of the energy difference between the hole transporting material and the electron transporting material is satisfied, holes in the hole transporting material in the mixed layer and electrons in the electron transporting material are allowed to stay in the hole transporting material and the electron transporting material, respectively, Can be smoothly formed. That is, when the above range is not satisfied, holes in the hole transporting material move into the electron transporting material in the mixed layer, electrons in the electron transporting material move to the hole transporting material, do.

As used herein, "HOMO" means the highest occupied molecular orbital, and "LUMO" means the lowest unoccupied molecular orbital.

In the present specification, the "HOMO energy level difference" and "LUMO energy level difference" mean the difference in absolute value of each energy value. In addition, the HOMO and LUMO energy levels are shown as absolute values.

In addition, the exciton binding energy in the present specification means the magnitude of the coulomb potential between electrons and charges in a molecule in the excited state.

The measurement of the HOMO energy level can be performed by UV (ultraviolet photoelectron spectroscopy), which measures the ionization potential of a material by irradiating the surface of the thin film with ultraviolet rays and detecting electrons protruding therefrom. Alternatively, the HOMO energy level can be measured by cyclic voltammetry (CV), which measures the oxidation potential through a voltage sweep after dissolving the analyte in a solvent together with an electrolytic solution. In the case of measuring the HOMO energy level in the thin film form, the UPS can measure more accurate value than CV, and the HOMO energy level in this specification is measured by the UPS method.

The LUMO energy level can be obtained by measuring inverse photoelectron spectroscopy (IPES) or electrochemical reduction potential. IPES is a method of irradiating an electron beam onto a thin film and measuring the light emitted therefrom to determine the LUMO energy level. In addition, the electrochemical reduction potential can be measured by measuring the reduction potential through a voltage sweep after dissolving the analyte in a solvent together with an electrolytic solution. Alternatively, the LUMO energy level can be calculated using the singlet energy level obtained by measuring the HOMO energy level and the degree of UV absorption of the target material.

According to an embodiment of the present invention, the hole transporting material of the mixed layer may include an aromatic amine group; Ditolylamine; An aromatic aniline group; Indoleacridine; And an aromatic silane group.

According to one embodiment of the present invention, the aromatic amine group may be a carbazole group, a phenylamine group, a diphenylamine group or the like, but is not limited thereto.

According to one embodiment of the present invention, the hole transport material of the mixed layer is NPB (4,4'-bis [N- (1-napthyl) -N-phenyl-amino] -biphenyl); (4,4'4 "-tris [3-methylphenyl (phenyl) amino] triphenylamine and m-MTDATA (4,4'4" -tri (N-carbazolyl) triphenylamine) Or more species.

The LUMO energy level of the m-MTDATA is 2 eV, and the HOMO energy level is 5.1 eV. The LUMO energy level of TCTA is 2.1 eV and the HOMO energy level is 5.5 eV.

According to an embodiment of the present invention, the hole transporting material of the mixed layer may be selected from the group consisting of arylamine, aromatic amine, thiophene, carbazole, fluorine derivative, N, N'-bis (phenyl) -benzidine (N, N'-bis (naphthalen- benzidine, N, N'-bis (naphthalen-2-yl) -N, N'-bis N'-bis (phenyl) -benzidine, N, N'-bis (3-methylphenyl) -N, N'- ) -benzidine, N, N'-bis (3-methylphenyl) -N, N'-bis (phenyl) -9,9-spirobifluorene, N'-bis (phenyl) -9,9-spirobifluorene, N, N'-bis (naphthalen- Bis (phenyl) -9,9-spirobifluorene), N, N'-bis (3-methylphenyl) -N, N'- -9,9-diphenyl-fluorene (N, N'-bis (3-methylphenyl) -N, N'- N, N'-bis (naphthalen-1-yl) -N, N'-bis (phenyl) -9,9- N, N'-bis (phenyl) -9,9-dimethyl-fluorene), N, N'-bis (naphthalen- N, N'-bis (phenyl) -9,9-diphenyl-fluorene), 2,2 ', 7,7'-tetrakis (N , N-diphenylamino) -9,9-spirobifluorene, 9,9-bis [4 - (N, N-bis-naphthalen-2-yl-amino) phenyl] -9H- 9H-fluorene), 9,9-bis [4- (N-naphthalen-1-yl-N-phenylamino) -phenyl] -9H- (N, N'-bis (diphenylphosphino) phenyl) -9H-fluorene, N, N'-bis (N, N-di-phenyl-amino) -9,9-spirobifluorene (2,2'-bis (N, N-di-phenyl-amino) -9,9-spirobifluorene), di- [4- ] Cyclohexane), 2,2 ', 7,7'-tetra (N, N-ditolyl) amino-9,9-spiro N, N ', N'-tetra-naphthalene-2-carboxylate, N, N'- N, N ', N'-tetra- (3-methylphenyl) -3,3'-dimethylbenzidine (N, N'N'-tetra-naphthalen- (N, N ', N'-tetra- (3-methylphenyl) -3,3'-dimethylbenzidine) N, N'-diphenylbenzene-1,4-diamine, N1, N4-diphenyl-N1, N4-di- Diamine, Tris (4- (quinolin-8-yl) phenyl) amine (Tris (4- (quinolin- Bis (3- (N, N-di (tert-butyldimethylsilyl) N, N ', N'-tetrakis (4-methoxyphenyl) benzidine, and N, N'-tetrakis And N, N'-diphenyl-N, N'-di- [4- (N, N -ditolyl-amino) phenyl] benzidine N, N'-diphenyl-N, N'-di- [4- (N, N-ditolylamino) phenyl] benzidine). However, the hole transporting material is not limited to the above-mentioned hole transporting material, and can be used as the hole transporting material if it has a strong electron donating property.

According to one embodiment of the present invention, the electron transporting material of the mixed layer includes a pyridine group; Triazine; Phosphine oxide groups; Benzofuran group; A dibenzofurane group; Benzothiophene group; A dibenzothiophene group; Benzophenone group; And an oxadiazole group. In the present invention,

According to one embodiment of the present invention, the electron transport material of the mixed layer is PBP (4-phenylbenzophenone); t-Bu-PBD (2- (biphenyl-4yl) -5- (4-tert-butylphenyl) -1,3,4-oxadiazole); 3TPYMB (tris- [3- (3-pyridyl) mesityl] borane); And bis-4,6- (3,5-di-3-pyridylphenyl) -2-methylpyrimidine-dine (B3PYMPM).

For t-Bu-PBD, the LUMO energy level is 2.4 eV and the HOMO energy level is 6.1 eV. The LUMO energy level of B3PYMPB is 3.2 eV and the HOMO energy level is 6.8 eV.

According to an embodiment of the present invention, the electron transporting material of the mixed layer is selected from the group consisting of 2,2 ', 2 "- (1,3,5-benzyltriyl) -tris (1-phenyl-1H-benzimidazole) (2,2 ', 2 "- (1,3,5-benzinetriyl) -tris (1-phenyl-1H-benzimidazole) (4-biphenyl) -5- (4-tert-butylphenyl) -1,3,4-oxadiazole, 2,9- 2,7-diphenyl-1,10-phenanthroline, 4,7-diphenyl-1,10-phenanthroline, Bis (2-methyl-8-quinolinolate) -4- (phenylphenolato) aluminum, 1,1-phenanthroline, Bis [2- (2,2'-bipyridin-6-yl) -1,3,4-oxadiazo-5-yl] -bipyridine-6-yl) -1,3,4-oxadiazo-5-yl] benzene), 6,6'-bis [5- (biphenyl- -2,2-bipyridyl (6,6'-bis [5- (biphenyl-4-yl) -1,3,4-oxadiazol- bipyridyl), 3- (4-biphenyl) -4-phenyl-5-tert- 4-phenyl-5-tert-butylphenyl-1,2,4-triazole), 4- (naphthalen-1-yl) -3,5- , 2,4-triazole, 2,9-bis (naphthalen-2-yl) -4, Bis (naphthalen-2-yl) -4,7-diphenyl-1,10-phenanthroline, 1,3- Tert-butylphenyl) -1,3,4-oxadiazo-5-yl] benzene (1,3-bis [2- ] benzene), tris (2,4,6-trimethyl-3- (pyridin-3-yl) phenyl) borane 1-methyl-2- (4- (naphthalen-2-yl) phenyl) -1H-imidazo [4,5f] [1,10] phenanthroline 2-yl) phenyl) -1Himidazo [4,5f] [1,10] phenanthroline, Phenyl-dipyrenylphosphine oxide, 3,3 ', 5,5'- Pyridyl) -phen-3-yl] biphenyl (3,3 ', 5,5'-tetra [(m- -Pyridyl) -phen-3-yl] benzene (1,3,5-tri [(3-pyridyl) -phen- Bis (4,6-diphenyl-1,3,5-triazin-2-yl) biphenyl (4,6'- bis (3,5-di [pyridin-3-yl] phenyl] benzene), 1,3-bis (4- (pyridin-3-yl) phenyl) silane), and the like. However, the present invention is not limited to the above-mentioned electron transporting material, but can be used as the electron transporting material if the material has a high electron affinity and a strong electron acceptor property.

According to one embodiment of the present disclosure, the mixed layer comprises a charge transfer complex of NPB (4,4'-bis [N- (1-napthyl) -N-phenyl-amino] -biphenyl) and PBP (4-phenylbenzophenone); Bu-PBD (2- (biphenyl-4yl) -5- (4-tert-butylphenyl) -1, M-MTDATA (4,4'4 "-tris [3-methylphenyl (phenyl) amino] triphenylamine) and 3TPYMB (tris- [3- (3-pyridyl) mesityl] borane ) Charge transfer complex; And charge transporting complexes of TCTA (4,4 ', 4 "-tri (N-carbazolyl) triphenylamine) and B3PYMPM (bis-4,6- (3,5-di-3-pyridylphenyl) In particular, in the case of the above-mentioned specific charge transfer complexes, the excellent effects of the above-described mixed layer can be maximized.

According to an embodiment of the present invention, the driving voltage of the organic light emitting device including the mixed layer is not higher than the driving voltage of the organic light emitting device not including the mixed layer, and exhibits a low driving voltage. Therefore, the organic light emitting element of the present specification can have excellent efficiency.

According to an embodiment of the present invention, the quantum efficiency of the organic light emitting device including the mixed layer may be improved by at least 10% as compared with the quantum efficiency of the organic light emitting device not including the mixed layer.

According to one embodiment of the present invention, the luminous efficiency (lm / W) of the organic light emitting device including the mixed layer can be improved by 20% or more as compared with the organic light emitting device not including the mixed layer.

According to one embodiment of the present invention, the organic light emitting device including the mixed layer can obtain better quantum efficiency due to a small donation of DF (Delayed Fluorescence).

According to one embodiment of the present invention, the organic light emitting device including the mixed layer may have improved quantum efficiency in a fluorescent or phosphorescent device. Specifically, the organic light emitting device including the mixed layer may have improved quantum efficiency in the fluorescent device. More specifically, the fluorescent element may be a fluorescent blue element.

According to one embodiment of the present invention, the thickness of the mixed layer may be 1 nm or more and 100 nm or less. Specifically, the thickness of the mixed layer may be 1 nm or more and 20 nm or less, or 1 nm or more and 10 nm or less.

When the thickness of the mixed layer exceeds 100 nm, the charge transport property may be impaired. Since the mobility of the charge can be lower than that of the single layer in the mixed layer, it is preferable that the mobility is made thinner than the thickness in the range where the mobility of the charge is dominant. That is, when the thickness of the mixed layer is within the above range, the charge transfer characteristics can be excellently exerted.

When the mixed layer in this specification is formed within the above-mentioned thickness range, the mixed layer can easily recycle the triplet exciton of the light emitting layer. That is, when the mixed layer is in the thickness range, the efficiency of the organic light emitting device is improved.

And the first electron transporting layer is doped with an n-type dopant by an n-type dopant. Specifically, the n-type dopant included in the first electron transport layer should be capable of generating a charge transfer reaction so that electrons can move from the n-type dopant to the first electron transport layer material. Specifically, the n-type dopant should be a material capable of forming more free electrons in the first electron transporting layer, and the position of the energy region in which the first electron transporting layer material can receive electrons from the n- LUMO energy level. When the n-type dopant is doped in the first electron transporting layer, the Fermi level of the first electron transporting layer is increased. That is, the Fermi level of the first electron transport layer is close to the LUMO energy level, and the charge transfer reaction is smooth.

Therefore, it is preferable that the HOMO energy level of the material that can be used as the n-type dopant is equal to or higher than the LUMO energy level of the first electron transport layer material. In addition, since the movement of electrons in the first electron transporting layer passes through the LUMO air-surface level of the first electron transporting layer material in the n-type dopant, the work function of the n-type dopant must be higher than the LUMO energy level of the first electron transporting layer material. When the n-type dopant is not a metal, the valence electron band of the n-type dopant should be higher than the LUMO energy level of the first electron transporting layer material.

According to one embodiment of the present invention, the n-type dopant may have a HOMO energy level of 3 eV or less.

According to an embodiment of the present invention, the n-type dopant may be a material having a work function of 3.0 eV or more and 4.0 eV or less.

Specifically, according to one embodiment of the present disclosure, the n-type dopant is an alkali metal; Alkaline earth metals; A halide of an alkali metal; Halides of alkaline earth metals, alkali metal oxides; Alkaline earth metal oxide; Carbonates of metals; And an organic material having a HOMO energy level of 3 eV or less.

According to an exemplary embodiment of the present disclosure, the n-type dopant is LiF, MgF _2, Li ₂ O, MgO, MnO, ScCO _3, Ru ₂ CO _3, TTN (tetrathianaphthacene), nose Balto sensor (cobaltocene; bis (cyclopentadienyl) -cobalt (II)), bis (terpyridine) ruthenium, and rhodamine B, pyronin B, and the like.

According to an embodiment of the present invention, the content of the n-type dopant may be 0.1 wt% or more and 30 wt% or less with respect to the amount before the first electron transporting layer.

If the concentration of the n-type dopant is higher within the above range, more electrons can be transferred to the first electron transporting layer, so that the Fermi level of the first electron transporting layer is increased, thereby improving conductivity and charge mobility.

However, if the concentration of the n-type dopant is excessively higher than the above-mentioned range, a shape of the n-type dopant may be formed, and the effect of the n-type dopant may be deteriorated. In addition, the amount of light absorbed by the n-type dopant increases, which may result in a problem of inefficiency of the organic light emitting device.

In the tandem organic light emitting device including two or more light emitting units according to one embodiment of the present invention, a charge generating layer or an intermediate electrode may be provided between the light emitting unit and the light emitting unit.

The charge generating layer may mean a layer in which holes and electrons are generated when a voltage is applied.

According to one embodiment of the present disclosure, the charge generating layer comprises a p-type organic layer; And an n-type organic compound layer closer to the anode than the p-type organic compound layer, and the p-type organic compound layer and the n-type organic compound layer can form an NP junction.

According to one embodiment of the present invention, the n-type organic compound layer can be in contact with the first electron transporting layer. Specifically, the charge transport layer may be provided between each light emitting unit, and the n-type organic compound layer of the charge generation layer may be provided in contact with the electron transport layer or the first electron transport layer doped with the n-type dopant of the adjacent light emitting unit.

According to an embodiment of the present invention, the difference between the HOMO energy level of the p-type organic layer and the LUMO energy level of the n-type organic layer may be 1 eV or less.

When the NP junction is formed, charge generation may occur at the LUMO level of the n-type organic layer and at the HOMO level of the p-type organic layer. Therefore, holes or electrons are easily formed by an external voltage or a light source. That is, holes are formed in the p-type organic layer and electrons are readily formed in the n-type organic layer by the NP junction. Since holes and electrons are simultaneously generated in the NP junction, electrons are transported toward the anode through the LUMO level of the n-type organic layer, and holes are transported toward the cathode through the HOMO level of the p-type organic layer.

According to an embodiment of the present invention, it is preferable that the n-type organic compound layer has a predetermined LUMO energy level with respect to the HOMO energy level of the p-type organic compound layer in order for charge generation by the NP junction to occur. If the HOMO level of the p-type organic material is smaller than the LUMO level of the n-type organic material, spontaneous charge generation can be achieved. For reference, the smaller the energy level, the greater the energy value of the electron. In order for spontaneous charge generation to occur, the HOMO level of the p-type organic material needs only to be smaller than the LUMO level of the n-type organic material, and the magnitude of the energy difference is not particularly limited. In other words, even if the difference between the HOMO level of the p-type organic material and the LUMO level of the n-type organic material is large, spontaneous charge generation occurs if the HOMO level of the p-type organic material is smaller than the LUMO level of the n-type organic material.

In the NP junction having the energy relation as described above, electrons at the HOMO level of the p-type organic material can move spontaneously to the vacant LUMO level of the n-type organic material. In this case, holes are generated at the HOMO level of the p-type organic layer and electrons are generated at the LUMO level of the n-type organic layer. This is the principle of charge generation. At the opposite energy level, spontaneous charge generation does not occur. In this case, it is necessary to change the vacuum level by the dipole at the interface in order to generate the charge. According to one embodiment of the present invention, it is revealed that the vacuum level (VL) movement due to the dipole effect can be about 1 eV at the NP junction interface, and the HOMO level of the p- The energy level is limited up to 1 eV as compared with the LUMO level of the organic material layer.

If the HOMO level of the p-type organic material and the LUMO level of the n-type organic material do not have the above-described energy relationship, the NP junction between the p-type organic layer and the n-type organic layer is not easily generated, do. That is, according to one embodiment of the present specification, the NP junction should satisfy not only the physical contact of the n-type organic layer and the p-type organic layer but also the energy relationship described above.

When such a charge generation structure is applied to a unit organic light emitting device, the charge injection barrier is lowered to enable driving of the low voltage device. In addition, the charge generating layer having the NP junction structure may function as a connection layer of each light emitting unit when the light emitting units are stacked to implement the tandem organic light emitting device.

According to one embodiment of the present disclosure, the n-type organic layer is selected from the group consisting of 2,3,5,6-tetrafluoro-7,7,8,8-tetracyanoquinodimethane (F4TCNQ), fluorine-substituted 3, 4,9,10-perylene tetracarboxylic dianhydride (PTCDA), cyano-substituted PTCDA, naphthalene tetracarboxylic dianhydride (NTCDA), fluorine-substituted NTCDA, cyano-substituted NTCDA , And an organic compound selected from the group consisting of compounds represented by the following formula (1).

[Chemical Formula 1]

Each of R1 to R6 is hydrogen; A halogen group; Nitrile group (-CN); A nitro group (-NO ₂ ); A sulfonyl group (-SO ₂ R); Sulfoxide group (-SOR); A sulfonamide group (-SO ₂ NR _2); Sulfonate groups (-SO ₃ R); A trifluoromethyl group (-CF _3); Ester group (-COOR); An amide group (-CONHR or -CONRR '); A substituted or unsubstituted straight or branched chain C1 to C12 alkoxy group; A substituted or unsubstituted straight or branched chain C1 to C12 alkyl group; A substituted or unsubstituted straight or branched chain C2 to C12 alkenyl group; A substituted or unsubstituted aromatic or non-aromatic heterocyclic group; A substituted or unsubstituted aryl group; A substituted or unsubstituted mono- or di-arylamine group; And a substituted or unsubstituted aralkylamine group,

R and R 'are each a substituted or unsubstituted C1 to C60 alkyl group; A substituted or unsubstituted aryl group; And a substituted or unsubstituted 5- to 7-membered aliphatic cyclic group.

According to one embodiment of the present invention, the organic light emitting device includes a hole injection layer; A hole blocking layer; A charge generation layer; An electron blocking layer; A charge generation layer; And an electron injection layer may be further included.

According to an embodiment of the present invention, the tandem organic light emitting device may further include a substrate below the anode or the cathode.

In this specification, charge means electron or hole.

In this specification, quantum efficiency is defined as the ratio of the number of injected charges to the number of emitted photons.

Generally, in the organic light emitting device, electrons are injected and transported from the cathode to the light emitting layer, and holes are injected and transported from the anode to the light emitting layer.

In an organic light emitting device, luminescence characteristics are one of important characteristics of the device. In order to efficiently emit light in the organic light emitting device, it is important that the charge balance in the light emitting region is achieved. For this purpose, it is necessary not only that the electrons transported from the cathode and the holes transported from the anode have to be quantitatively balanced but also the point where the electrons and the holes meet together to form an exciton together with the emission region.

According to one embodiment of the present invention, the organic light emitting device including the mixed layer can improve the charge balance.

Hereinafter, each layer constituting the organic light emitting element according to the embodiment of the present invention will be described in detail. The materials of each layer described below may be a single material or a mixture of two or more materials.

Board

The substrate may be a glass substrate or a transparent plastic substrate having excellent transparency, surface smoothness, ease of handling, and waterproofness, but is not limited thereto and is not limited as long as it is a substrate commonly used in organic light emitting devices.

Anode

The anode is preferably made of a material having a large work function so that injection of holes into the organic material layer can be smoothly performed. Specifically, it may include a metal, a metal oxide, or a conductive polymer. The conductive polymer may include an electrically conductive polymer. For example, the anode may have a work function value of about 3.5 to 5.5 eV. Exemplary conductive materials include carbon, aluminum, vanadium, chromium, copper, zinc, silver, gold, other metals and alloys thereof; Zinc oxide, indium oxide, tin oxide, indium tin oxide (ITO), indium zinc oxide and other similar metal oxides; ZnO: Al and SnO _2: a mixture of oxide and metal, such as Sb; And conductive polymers such as poly (3-methylthiophene), poly [3,4- (ethylene-1,2-dioxy) thiophene] (PEDT), polypyrrole and polyaniline.

As the anode material, a transparent material may be used, or an opaque material may be used. In the case of a structure in which light is emitted in the anode direction, the anode may be formed to be transparent. Here, the transparency means that light emitted from the organic material layer can be transmitted, and the transparency of light is not particularly limited.

For example, when the organic light emitting element according to the present specification is a top emission type and the anode is formed on the substrate before formation of the organic layer and the cathode, an opaque material having excellent light reflectance as well as a transparent material as the anode material may be used. For example, when the organic light emitting device according to the present specification is of a back light emission type and the anode is formed on the substrate before formation of the organic material layer and the cathode, a transparent material is used as the anode material, or a thin film is formed so that the opaque material becomes transparent .

Cathode

The cathode material is preferably a material having a small work function so that electron injection can be easily performed. For example, in this specification, a material having a work function of 2 eV to 5 eV may be used as the cathode material. The cathode may include, but is not limited to, metals such as magnesium, calcium, sodium, potassium, titanium, indium, yttrium, lithium, gadolinium, aluminum, silver, tin and lead or alloys thereof; Layer structure materials such as LiF / Al or LiO ₂ / Al, and the like.

The cathode may be formed of the same material as the anode. In this case, the cathode may be formed of materials exemplified as the material of the anode in advance. Alternatively, the cathode or anode may comprise a transparent material.

Hole injection layer ( HIL )

As the hole injection layer material, it is preferable that the highest occupied molecular orbital (HOMO) of the hole injecting material is between the work function of the anode material and the HOMO of the surrounding organic layer. Specific examples of the hole injecting material include metal porphyrine, oligothiophene, arylamine-based organic materials; Hexanitrile hexaazatriphenylene, and quinacridone-based organic materials; Perylene organic materials; Anthraquinone, polyaniline, polythiophene based conductive polymers, and the like, but the present invention is not limited thereto.

Hole transport layer ( HTL )

As the hole transporting layer material, a material capable of transporting holes from the anode or the hole injecting layer and transferring the holes to the light emitting layer is preferable. Specific examples include arylamine-based organic materials, conductive polymers, and block copolymers having a conjugated portion and a non-conjugated portion together, but are not limited thereto.

The light- ( EML )

Since hole transport and electron transport occur simultaneously in the light emitting layer, the light emitting layer may have both n-type and p-type characteristics. For convenience sake, it can be defined as an n-type luminescent layer when the electron transport is faster than the hole transport, and a p-type luminescent layer when the hole transport is faster than the electron transport.

The n-type light emitting layer may include, but is not limited to, aluminum tris (8-hydroxyquinoline) (Alq ₃ ); 8-hydroxyquinoline beryllium (BAlq); A benzoxazole-based compound, a benzothiazole-based compound, or a benzimidazole-based compound; Polyfluorene compounds; Silacyclopentadiene (silole) -based compounds, and the like.

The p-type light emitting layer may include, but is not limited to, a carbazole compound; Anthracene-based compounds; Polyphenylene vinylene (PPV) based polymers; Or spiro compounds, and the like.

As the light emitting layer material, a material capable of emitting light in the visible light region by transporting and receiving holes and electrons from the hole transporting layer and the electron transporting layer, respectively, is preferably a material having good quantum efficiency for fluorescence or phosphorescence. Specific examples include 8-hydroxy-quinoline aluminum complex (Alq ₃ ); Carbazole-based compounds; Dimerized styryl compounds; BAlq; 10-hydroxybenzoquinoline-metal compounds; Benzoxazole, benzthiazole and benzimidazole compounds; Polymers of poly (p-phenylenevinylene) (PPV) series; Spiro compounds; Polyfluorene; Rubrene, and the like, but are not limited thereto.

Electron transport layer ( ETL )

The electron transport layer material is a material capable of transferring electrons from the cathode well into the light emitting layer, and a material having high mobility to electrons is suitable. Specific examples include an Al complex of 8-hydroxyquinoline; Complexes containing Alq ₃ ; Organic radical compounds; Hydroxyflavone-metal complexes, and the like, but are not limited thereto.

According to one embodiment of the present disclosure, the organic light emitting device may include a light extracting layer. Specifically, according to one embodiment of the present disclosure, the light extracting layer may be an inner light extracting layer or an outer light extracting layer.

According to an embodiment of the present invention, the organic light emitting diode may further include a substrate. Specifically, the organic light emitting diode may include the anode or the cathode on the substrate.

According to an embodiment of the present invention, the organic light emitting device further includes a substrate, the anode or the cathode is provided on the substrate, and the organic light emitting device is provided between the substrate and the anode or between the substrate and the cathode. And may further include an inner light scattering layer.

According to one embodiment of the present disclosure, the inner light-scattering layer may include a flat layer.

According to an embodiment of the present invention, the organic light emitting device further includes a substrate, the anode or the cathode is provided on the substrate, and a surface of the substrate facing the anode or the cathode, And may further include a light scattering layer.

According to an embodiment of the present invention, the inner light-scattering layer or the outer light-scattering layer is not particularly limited as long as it can induce light scattering and improve the light extraction efficiency of the organic light emitting device. Specifically, according to one embodiment of the present invention, the light scattering layer may be a structure in which scattering particles are dispersed in the binder.

According to an embodiment of the present invention, the light scattering layer may be formed directly on the substrate by spin coating, bar coating, slit coating, or the like, or may be formed in the form of a film.

According to an embodiment of the present invention, the organic light emitting device may be a flexible organic light emitting device. In this case, the substrate may comprise a flexible material. Specifically, the substrate may be a glass, a plastic substrate, or a film-like substrate in the form of a thin film which can be bent.

The material of the plastic substrate is not particularly limited, but may be a film including PET, PEN, PEEK and PI in a single layer or a multilayer form.

The present invention provides a display device including the organic light emitting device. In the display device, the organic light emitting diode may serve as a pixel or a backlight. Besides, the configuration of the display device may be applied to those known in the art.

The present specification provides a lighting apparatus including the organic light emitting element. In the illumination device, the organic light emitting element plays a role of a light emitting portion. In addition, configurations necessary for the illumination device can be applied to those known in the art.

101: anode
201: hole transport layer
301: light emitting layer
401: mixed layer
501: First electron transport layer
601: cathode
701: Second electron transport layer

Claims (33)

Anode; A cathode opposite to the anode; And an organic layer including a light emitting layer provided between the anode and the cathode,
Wherein the organic material layer includes a first electron transporting layer and a mixed layer between the light emitting layer and the cathode,
Wherein the first electron transporting layer and the mixed layer are provided in contact with each other,
Wherein the mixed layer comprises at least one hole transporting material and at least one electron transporting material,
Wherein the first electron transporting layer is doped with an n-type dopant. Anode; A cathode opposite to the anode; And at least two light emitting units provided between the anode and the cathode,
Wherein each of the light emitting units includes an organic layer including a light emitting layer,
At least one organic layer of the light emitting unit includes a first electron transporting layer and a mixed layer between the light emitting layer and the cathode,
Wherein the first electron transporting layer and the mixed layer are provided in contact with each other,
Wherein the mixed layer comprises at least one hole transporting material and at least one electron transporting material,
Wherein the first electron transporting layer is doped with an n-type dopant. The method according to claim 1 or 2,
Wherein the mixed layer is provided between the light emitting layer and the first electron transporting layer. The method of claim 3,
Wherein the organic layer further comprises a second electron transport layer provided between the light emitting layer and the mixed layer. The method according to claim 1 or 2,
Wherein the mass ratio of the hole transporting material to the electron transporting material in the mixed layer is 1: 4 to 4: 1. The method according to claim 1 or 2,
Wherein a difference between the HOMO energy level of the hole transporting material and the electron transporting material of the mixed layer is 0.2 eV or more. The method according to claim 1 or 2,
Wherein the LUMO energy level difference between the hole transporting material and the electron transporting material of the mixed layer is 0.2 eV or more. The method according to claim 1 or 2,
Wherein a difference between a LUMO energy level of the electron transporting material of the mixed layer and a HOMO energy level of the hole transporting material is 2 eV or more. The method according to claim 1 or 2,
Wherein the difference between the ionization potential of the hole transporting material and the electron transporting material of the mixed layer is 0.2 eV or more. The method according to claim 1 or 2,
Wherein the difference in electron affinity between the hole transporting material and the electron transporting material in the mixed layer is 0.2 eV or more. The method according to claim 1 or 2,
Wherein the difference between the electron affinity of the electron transporting material of the mixed layer and the ionization potential of the hole transporting material is 2 eV or more. The method according to claim 1 or 2,
The hole transport material of the mixed layer may include aromatic amine groups; Ditolylamine; An aromatic aniline group; Indoleacridine; An aromatic silane group, and an aromatic silane group. The method according to claim 1 or 2,
The electron transporting material of the mixed layer may be a pyridine group; Phosphine oxide groups; Benzofuran group; A dibenzofurane group; Benzothiophene group; A dibenzothiophene group; Benzophenone group; And an oxydazole group. 2. The organic light-emitting device according to claim 1, The method according to claim 1 or 2,
The hole-transporting material of the mixed layer is NPB (4,4'-bis [N- (1-napthyl) -N-phenyl-amino] -biphenyl); (4,4'4 "-tris [3-methylphenyl (phenyl) amino] triphenylamine and m-MTDATA (4,4'4" -tri (N-carbazolyl) triphenylamine) Or more. The method according to claim 1 or 2,
The electron transport material of the mixed layer may be PBP (4-phenylbenzophenone); t-Bu-PBD (2- (biphenyl-4yl) -5- (4-tert-butylphenyl) -1,3,4-oxadiazole); 3TPYMB (tris- [3- (3-pyridyl) mesityl] borane); And B3PYMPM (bis-4,6- (3,5-di-3-pyridylphenyl) -2-methylpyrimidine-dine). The method according to claim 1 or 2,
Wherein the mixed layer comprises the hole transporting material and a charge transfer complex of the electron transporting material. 18. The method of claim 16,
The mixed layer may be a charge transfer complex of NPB (4,4'-bis [N- (1-napthyl) -N-phenyl-amino] -biphenyl) and PBP (4-phenylbenzophenone); Bu-PBD (2- (biphenyl-4yl) -5- (4-tert-butylphenyl) -1, M-MTDATA (4,4'4 "-tris [3-methylphenyl (phenyl) amino] triphenylamine) and 3TPYMB (tris- [3- (3-pyridyl) mesityl] borane ) Charge transfer complex; And charge transfer complexes of TCTA (4,4 ', 4 "-tri (N-carbazolyl) triphenylamine) and B3PYMPM (bis-4,6- (3,5-di-3-pyridylphenyl) ≪ / RTI > and at least one organic compound selected from the group consisting of organic compounds. The method according to claim 1 or 2,
Wherein the mixed layer has a thickness of 1 nm or more and 100 nm or less. The method according to claim 1 or 2,
Wherein the n-type dopant has a HOMO energy level of 3 eV or less. The method according to claim 1 or 2,
Wherein the n-type dopant has a work function of 3.0 eV or more and 4.0 eV or less. The method according to claim 1 or 2,
The n-type dopant may be an alkali metal; Alkaline earth metals; A halide of an alkali metal; Halides of alkaline earth metals, alkali metal oxides; Alkaline earth metal oxide; Carbonates of metals; And an organic material having a HOMO energy level of 3 eV or less. The method according to claim 1 or 2,
The organic light emitting device includes a hole injection layer; A hole blocking layer; A charge generation layer; An electron blocking layer; A charge generation layer; And an electron injection layer. The organic light emitting device according to claim 1, The method of claim 2,
And a charge generating layer or an intermediate electrode between the light emitting unit and the light emitting unit. 24. The method of claim 23,
Wherein the charge generating layer comprises a p-type organic layer; And an n-type organic compound layer closer to the anode than the p-type organic compound layer, wherein the p-type organic compound layer and the n-type organic compound layer form an NP junction. 27. The method of claim 24,
Wherein the difference between the HOMO energy level of the p-type organic layer and the LUMO energy level of the n-type organic layer is 1 eV or less. 27. The method of claim 24,
And the n-type organic compound layer is in contact with the first electron transporting layer. 27. The method of claim 24,
Wherein the n-type organic compound layer is selected from the group consisting of 2,3,5,6-tetrafluoro-7,7,8,8-tetracyanoquinodimethane (F4TCNQ), fluorine-substituted 3,4,9,10-perylenetetra (PTCDA), cyano-substituted PTCDA, naphthalene tetracarboxylic dianhydride (NTCDA), fluorine-substituted NTCDA, cyano-substituted NTCDA, and compounds of the formula Organic light emitting device comprising:
[Chemical Formula 1]

Each of R1 to R6 is hydrogen; A halogen group; Nitrile group (-CN); A nitro group (-NO ₂ ); A sulfonyl group (-SO ₂ R); Sulfoxide group (-SOR); A sulfonamide group (-SO ₂ NR _2); Sulfonate groups (-SO ₃ R); A trifluoromethyl group (-CF _3); Ester group (-COOR); An amide group (-CONHR or -CONRR '); A substituted or unsubstituted straight or branched chain C1 to C12 alkoxy group; A substituted or unsubstituted straight or branched chain C1 to C12 alkyl group; A substituted or unsubstituted straight or branched chain C2 to C12 alkenyl group; A substituted or unsubstituted aromatic or non-aromatic heterocyclic group; A substituted or unsubstituted aryl group; A substituted or unsubstituted mono- or di-arylamine group; And a substituted or unsubstituted aralkylamine group,
R and R 'are each a substituted or unsubstituted C1 to C60 alkyl group; A substituted or unsubstituted aryl group; And a substituted or unsubstituted 5- to 7-membered aliphatic cyclic group. The method according to claim 1 or 2,
Wherein the organic light emitting device further comprises a substrate, the anode or the cathode is provided on the substrate,
And an internal light-scattering layer provided between the substrate and the anode or between the substrate and the cathode. The method according to claim 1 or 2,
Wherein the inner light-scattering layer comprises a flat layer. The method according to claim 1 or 2,
Wherein the organic light emitting device further comprises a substrate, the anode or the cathode is provided on the substrate,
And an external light-scattering layer on a surface of the substrate facing the surface on which the anode or the cathode is provided. The method according to claim 1 or 2,
Wherein the organic light emitting element is a flexible organic light emitting element. A display device comprising the organic light emitting device according to claim 1 or 2. A lighting device comprising the organic light-emitting device according to claim 1 or 2.

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