CN104078623B - A kind of organic electroluminescence device, organic electroluminescence display device and method of manufacturing same - Google Patents

Abstract

The invention provides an organic electroluminescent device and an organic electroluminescent display device, belonging to the field of display technology, which can solve the problem that the mass percentage of the existing organic electroluminescent device and organic electroluminescent display device is too low Or too high will cause the problem of impure luminous color or low luminous efficiency of the device. The organic electroluminescent device and organic electroluminescent display device of the present invention can adjust the charge transport of the organic light-emitting layer and widen the exciton recombination region of the organic light-emitting layer due to the addition of dopants in the organic light-emitting layer, which overcomes the problem of guest materials. The shortcomings of impure luminous color and low luminous efficiency caused by too much or too little host material make the adjustment range of the mass percentage of the guest material in the organic light-emitting layer larger, and the selection range of materials is wider.

Description

An organic electroluminescence device, an organic electroluminescence display device

technical field

The invention belongs to the field of display technology, and in particular relates to an organic electroluminescence device and an organic electroluminescence display device comprising the organic electroluminescence device.

Background technique

Organic Light Emitting Diode (OLED, Organic Light Emitting Diode) display device has many advantages such as full solid state, active light emission, fast response speed, high contrast, no viewing angle limitation, and flexible display. It is a kind developed in the middle of the 20th century. The new display technology is widely used in people's daily production and life. Although liquid crystal display is currently the most mainstream flat-panel display, especially after combining thin-film transistor technology, its response speed, brightness, contrast and lightness of the display have been greatly improved. However, since the liquid crystal display panel itself cannot emit light, it must be used The backlight illuminates the panel to emit light, so there are certain limitations and no further improvement can be obtained. Therefore, the OLED display device will become the most ideal flat-panel display device of the next generation. Its superior performance and huge market potential have attracted many manufacturers and scientific research institutions all over the world to invest in the production and research and development of OLED display devices.

The structure of an existing organic electroluminescent device is shown in Figure 1, an anode layer 1, a hole injection layer 2, a hole transport layer 3, an organic light-emitting layer 4, an electron transport layer 5, Electron injection layer 6 and cathode layer 7. The organic light emitting layer 4 includes a host material and a guest material for emitting light. Driven by a certain voltage, electrons and holes are injected from the cathode and anode into the electron transport layer 5 and the hole transport layer 3 respectively, and the electrons and holes migrate to the organic light-emitting layer through the electron transport layer 5 and the hole transport layer 3 respectively, And meet in the light-emitting layer to form excitons, and transfer energy from the host material to the guest material to excite the molecules of the guest material to achieve light emission.

Wherein, the host material as the charge transport material includes hole transport material and electron transport material, and the guest material is used to receive the energy of the host material to realize light emission. For example, for red and green light guest materials, phosphorescent guest materials are mostly used. Through the structural design of host materials and guest materials, energy transfer from the host to the guest is obtained, thereby realizing the luminescence of the phosphorescent guest materials. One advantage of phosphorescence is that all excitons formed in a singlet or triplet excited state (obtained by the recombination of electrons and holes in the light-emitting layer) can participate in the light emission. Since the energy of the lowest triplet excited state in organic molecules is slightly lower than that of the lowest singlet excited state, singlet to triplet states can be achieved for most phosphorescent guest materials (phosphorescent organometallic compounds) The rapid decay achieves luminescence. Phosphorescent organic light-emitting layer (host material and guest material) compared with fluorescent organic light-emitting layer (host material is fluorescent material, no guest material) (only 25% of excitons can achieve light emission), its luminous efficiency is greatly improved.

However, the ratio of the guest material (relative to the mass of the host material) has a great influence on the luminous spectrum and luminous efficiency. When the mass fraction of the guest material is small, the energy of the host material cannot be completely transferred to the guest material, causing the host material to emit light itself. The emission color of the organic electroluminescence device is impure. However, when the mass fraction of the guest material is high, the exciton quenching phenomenon occurs, which reduces the luminous efficiency.

Contents of the invention

The purpose of the present invention is to solve the problem that the organic electroluminescent device and organic electroluminescent display device in the prior art have impure luminous color or low luminous efficiency due to too low or too high mass percentage of the guest material, and provide a An organic electroluminescent device and an organic electroluminescent display device capable of balancing charge transport and improving luminous efficiency.

The technical solution adopted to solve the technical problem of the present invention is an organic electroluminescence device, comprising an anode layer, a hole injection layer, a hole transport layer, an organic light-emitting layer, an electron transport layer, an electron injection layer and a cathode layer, the The organic light emitting layer includes a host material and a guest material for emitting light, and the organic light emitting layer also includes a dopant for adjusting charge transport.

Preferably, the mass percentage of the dopant relative to the host material increases or decreases along the direction from the hole transport layer to the electron transport layer.

Preferably, the mass percentage of the dopant relative to the host material increases linearly or decreases linearly, or increases or decreases gradually.

Preferably, the host material is an electron transport material, and the dopant is a hole transport material; or

The host material is a hole-transporting material, and the dopant is an electron-transporting material.

Preferably, the hole-transporting material is selected from N,N'-diphenyl-N,N'-(1-naphthyl)-1,1'-biphenyl-4,4'-diamine , 4,4'-bis(9-carbazole)biphenyl, 4,4'-bis(2,2-distyryl)-1,1'-biphenyl, 5,6,11,12-tetra Any of the phenyl tetracenes.

Preferably, the electron-transporting material is selected from tris(8-hydroxyquinoline)aluminum, 1,3,5-tris(1-phenyl-1H-benzimidazol-2-yl)benzene, 4, Any one of 7-diphenyl-1,10-phenanthroline.

Preferably, the mass percentage of the dopant is 0.1%-30% based on the mass of the host material as 100%.

Another object of the present invention is to provide an organic electroluminescent display device, which comprises the above organic electroluminescent device.

The organic electroluminescent device and the organic electroluminescent display device of the present invention can adjust the charge transport of the organic light-emitting layer so that the exciton recombination region of the organic light-emitting layer becomes It overcomes the shortcomings of impure luminous color and low luminous efficiency caused by too much or too little guest material in the host material; it makes the mass percentage of the guest material in the organic light-emitting layer more adjustable, and the material selection range is wider.

Description of drawings

FIG. 1 is a schematic diagram of the structure of an organic electroluminescent device.

in:

1. Anode layer; 2. Hole injection layer; 3. Hole transport layer; 4. Organic light-emitting layer; 5. Electron transport layer; 6. Electron injection layer; 7. Cathode layer.

detailed description

In order to enable those skilled in the art to better understand the technical solutions of the present invention, the present invention will be further described in detail below in conjunction with the accompanying drawings and specific embodiments.

For ease of reference, the full names and structural formulas of the organic compounds involved in the embodiments of the present invention are listed below:

The present invention provides an organic electroluminescent device, comprising an anode layer 1, a hole injection layer 2, a hole transport layer 3, an organic light-emitting layer 4, an electron transport layer 5, an electron injection layer 6 and a cathode layer 7, the organic The light-emitting layer includes a host material and a guest material for emitting light, and the organic light-emitting layer 4 also includes a dopant for adjusting charge transport.

The overall structure of the organic electroluminescent device of the present invention is basically the same as that of the prior art, except that the organic light-emitting layer includes a host material, a guest material for light emission, and a dopant for adjusting charge transport.

The invention adds a dopant for adjusting charge transport in the organic light-emitting layer, which can adjust the charge transport of the organic light-emitting layer to widen the exciton recombination region of the organic light-emitting layer, and overcomes the problem of too much or too much guest material in the host material. The disadvantages of impure luminescent color and low luminous efficiency caused by too little amount make the adjustment range of the mass percentage of the guest material of the organic light-emitting layer larger, and the selection range of materials is wider.

Preferably, the mass percentage of the dopant relative to the host material increases or decreases along the direction from the hole transport layer to the electron transport layer.

The exciton recombination region of the organic light emitting layer is widened by adjusting the mass percentage of the dopant in different sections of the organic light emitting layer to adjust the charge transport of the organic light emitting layer.

Preferably, the mass percentage of the dopant relative to the host material increases linearly or decreases linearly, or increases or decreases gradually.

Preferably, the host material is an electron-transporting material, and the dopant is a hole-transporting material; or

The host material is a hole-transporting material, and the dopant is an electron-transporting material.

Preferably, the hole-transporting material is selected from N,N'-diphenyl-N,N'-(1-naphthyl)-1,1'-biphenyl-4,4'-diamine ( NPB), 4,4'-bis(9-carbazole)biphenyl (CBP), 4,4'-bis(2,2-distyryl)-1,1'-biphenyl (DPVBi), 5 , Any one of 6,11,12-tetraphenyltetracene (Rubrene).

Preferably, the electron-transporting material is selected from tris(8-hydroxyquinoline)aluminum (Alq ₃ ), 1,3,5-tris(1-phenyl-1H-benzimidazol-2-yl)benzene (TPBi), any one of 4,7-diphenyl-1,10-phenanthroline (Bephen).

Preferably, the mass percentage of the dopant is 0.1%-30% based on the mass of the host material as 100%.

Example 1

As shown in Figure 1, this embodiment provides an organic electroluminescence device, comprising an anode layer 1, a hole injection layer 2, a hole transport layer 3, an organic light-emitting layer 4, an electron transport layer 5, an electron injection layer 6 and The cathode layer 7, the organic light-emitting layer includes a host material and a guest material for emitting light, and the organic light-emitting layer 4 also includes a dopant for adjusting charge transport.

In this embodiment, the structure design of the red light organic light-emitting layer is as follows:

The dopant rubrene is divided into n regions from the interface of the hole transport layer 3/organic light-emitting layer 4 to the end of the interface of the electron transport layer 5/organic light-emitting layer 4 (n can be a natural number above 2). In this embodiment n is 3, and the mass percentage of the dopant rubrene in each region increases with a certain gradient.

Specifically, the structure of the red organic electroluminescent device is as follows: ITO/CuPc (40nm)/NPB (40nm)/Alq ₃ :rubrene(5wt%):DCJTB(2wt%)(15nm)/Alq ₃ :rubrene(10wt%) ):DCJTB(2wt%)(15nm)/Alq ₃ :rubrene(15wt%):DCJTB(2wt%)(15nm)/Alq ₃ (40nm)/LiF(1nm)/Al(120nm).

Wherein, ITO is indium tin oxide; CuPc is copper phthalocyanine; LiF is lithium fluoride; the host material of the organic light-emitting layer 4 is Alq ₃ , the guest material is DCJTB, and the dopant is rubrene (rubrene). Taking the red light-emitting system as an example, it should be understood that other blue and green light-emitting systems are also feasible.

In this embodiment, the host material Alq ₃ is an electron-transporting material, the guest material is DCJTB, which is a hole-transporting material, and the dopant rubrene is a hole-transporting material.

Among them, the guest material DCJTB is a hole-transporting material, which also has a certain ability to adjust the hole-transporting ability of the host material, but the mass fraction of the guest material DCJTB cannot be too low or too high. When the mass fraction of the guest material DCJTB is too low, the host material The energy of the material cannot be completely transferred to the guest material, causing the host material itself to emit light, and the luminescent color of the device is impure; when the mass fraction of DCJTB in the guest material is too high, exciton quenching is prone to occur, which reduces the luminous efficiency.

Therefore, the guest material DCJTB is kept at a mass percentage with a better luminous effect, for example, 2wt% in this embodiment;

The hole transport ability of the host material is enhanced by adding the dopant rubrene; and then the charge transport of the organic light-emitting layer is balanced to improve the luminous efficiency. The mass percentage of the dopant rubrene in the above device is divided into three gradients, 5wt%, 10wt%, and 15wt%, so as to improve the hole transport ability of the organic light-emitting layer and improve the luminous efficiency.

When the dopant rubrene is not doped, the electron transport ability of the host material Alq ₃ is much greater than the hole, so the recombination region of the excitons is close to the interface of the organic light-emitting layer/hole transport layer, and the exciton recombination The area is small, and it is easy to be quenched with the hole transport material.

The dopant rubrene in the red organic light-emitting system in this embodiment provides an energy level ladder, which is beneficial to the transmission of energy from the host to the guest. At the same time, since the dopant rubrene is a hole-transporting material, its The transport ability is stronger than that of the host material Alq ₃ , so the overall hole transport ability of the organic light-emitting layer is enhanced, and the exciton recombination region of the organic light-emitting layer is widened.

In this embodiment, the doping concentration gradually increases from the interface of the hole transport layer/light emitting layer to the interface of the electron transport layer/light emitting layer, so that the concentration distribution of holes in the dopant shows a trend of changing from low to high. In contrast, since the host is an electron-transporting material, the hole concentration in the host material is low, and the hole density close to the hole-transporting layer is high during the hole-transporting process, and the density close to the electron-transporting layer is relatively high. Low, contrary to the change trend of the mass percentage of the dopant relative to the host material, it achieves the effect of balancing the hole concentration, thereby adjusting the transport balance of holes and electrons, and improving the luminous efficiency;

At the same time, due to the shortcomings of impure luminous color and low luminous efficiency caused by too much or too little guest material in the host material, adding a dopant as another substance that regulates charge transport can make the guest material of the organic light-emitting layer The adjustment range of mass percentage is larger, and the selection range of materials is wider. For example, the guest material can be selected from other materials with weaker hole regulation ability, or its mass percentage is in an optimal light-emitting state.

The luminous efficiency of the red organic electroluminescence device in this embodiment is increased from less than 2 cd/A to more than 5 cd/A compared to that without gradient doping of rubrene.

It should be understood that, if the host material is a hole-transporting material, the electron-transporting material should be selected for doping, so as to adjust the electron-transporting capability of the host material.

It should be understood that the hole-transporting material is selected from N,N'-diphenyl-N,N'-(1-naphthyl)-1,1'-biphenyl-4,4'-diamine (NPB ), 4,4'-bis(9-carbazole)biphenyl (CBP), 4,4'-bis(2,2-distyryl)-1,1'-biphenyl (DPVBi), 5, Any one of 6,11,12-tetraphenyltetracene (Rubrene).

It should be understood that the electron transport type material is selected from tris(8-quinolinolato)aluminum (Alq ₃ ), 1,3,5-tris(1-phenyl-1H-benzimidazol-2-yl)benzene ( TPBi), any one of 4,7-diphenyl-1,10-phenanthroline (Bephen).

The guest material can be selected from 4-(dicyanomethylene)-2-methyl-6-(4-dimethylaminostyryl)-4H-pyran (DCM), 4-dicyanomethylene-2 -tert-butyl-6-(1,1,7,7-tetramethyljulonidine vinyl)pyran (DCJTB), bis(2-phenylpyridine)iridium acetylacetonate (Ir(ppy)2 (acac)), (acetylacetonate) bis(2-methyldibenzo[F,H]quinoxaline) iridium (Ir(mphq)2(acac)), 5,6,11,12-tetraphenyl Rubrene, 2,3,6,7-tetrahydro-1,1,7,7-tetramethyl-1H,5H,11H-10-(2-benzothiazolyl)-quinolazine And any one of [9,9A,1GH]coumarin (C545T).

Example 2

This embodiment provides a structure of an organic electroluminescent device, specifically as follows:

ITO/fluorocarbon(1nm)/NPB(120nm)/Alq ₃ :NPB(5wt%):

C545T(1wt%)(10nm)/Alq ₃ :NPB(10wt%):C545T(1wt%)(10nm)/Alq ₃ :NPB(30wt%):C545T(1wt%)(10nm)/Alq ₃ (40nm) /LiF(1nm)/Al(120nm).

Among them, ITO is indium tin oxide; fluorocarbon is fluorocarbon; the host material is Alq ₃ , the guest material is C545T, and the dopant is NPB.

In this embodiment, the host material Alq ₃ is an electron-transporting material, the guest material is C545T, which is a hole-transporting material, and the dopant NPB is a hole-transporting material.

Among them, the guest material C545T is a hole-transporting material, which can also regulate the hole-transporting ability of the host material, but the mass fraction of the guest material C545T cannot be too low or too high. When the mass fraction of the guest material C545T is too low, the host material The energy of the material cannot be completely transferred to the guest material, causing the host material itself to emit light, and the luminescent color of the device is impure; when the mass fraction of C545T in the guest material is too high, the exciton quenching phenomenon is prone to occur, which reduces the luminous efficiency.

Therefore, keep the guest material C545T at a mass percentage with better luminous effect, for example, 1wt% in this embodiment;

The hole transport ability of the host material is enhanced by adding the dopant NPB, so as to balance the charge transport of the organic light-emitting layer and improve the luminous efficiency. The mass percentage of the dopant NPB in the above-mentioned device is divided into three gradients, 5wt%, 10wt%, and 30wt%, so as to improve the hole transport capability of the organic light-emitting layer and improve the luminous efficiency.

When the dopant NPB is not doped, because the electron transport ability of the host material Alq ₃ is much greater than that of holes, the recombination region of the excitons is close to the interface of the organic light-emitting layer/hole transport layer, and the exciton recombination region is relatively small. Small, easy to quench with hole transport materials.

The dopant NPB in the red organic light-emitting system in this embodiment provides an energy level ladder, which is beneficial to the transmission of energy from the host to the guest. At the same time, because the dopant NPB is a hole-transporting material, its hole-transporting ability is stronger than that of The host material is Alq ₃ , so the overall hole transport capability of the organic light-emitting layer is enhanced, and the exciton recombination region of the organic light-emitting layer is broadened.

In this embodiment, the doping concentration gradually increases from the interface of the hole transport layer/light emitting layer to the interface of the electron transport layer/light emitting layer, so that the concentration distribution of holes in the dopant shows a trend of change from low to high, In contrast, since the host is an electron-transporting material, the hole concentration in the host material is low, and the hole density close to the hole-transporting layer is high during the hole-transporting process, and the density close to the electron-transporting layer is relatively high. Low, contrary to the change trend of the mass percentage of the dopant relative to the host material, it achieves the effect of balancing the hole concentration, thereby adjusting the transport balance of holes and electrons, and improving the luminous efficiency. At the same time, due to the shortcomings of impure luminous color and low luminous efficiency caused by too much or too little guest material in the host material, adding dopants as another substance that regulates charge transport can make the guest material of the organic light-emitting layer The mass percentage adjustment range is larger, and the material selection range is wider. For example, the guest material can choose other materials with weaker hole adjustment ability, or make its mass percentage in the optimal light-emitting state

Compared with the NPB without gradient doping, the luminous efficiency of the red organic electroluminescent device in this embodiment is increased from less than 7.0 cd/A to more than 8.5 cd/A.

It should be understood that the mass percentage of the dopant can be linearly increased, or gradiently decreased or linearly decreased according to the specific application; similarly, the mass fraction of the dopant can be adjusted between 0.1%-30% according to the specific application. Linear increase in amplitude range, or gradient decrease or linear decrease.

Example 3

This embodiment provides an organic electroluminescent display device, including the above-mentioned organic electroluminescent device. The organic electroluminescent display device may be any product or component with a display function such as an OLED panel, a mobile phone, a tablet computer, a television set, a monitor, a notebook computer, a digital photo frame, a navigator, and the like.

It can be understood that, the above embodiments are only exemplary embodiments adopted for illustrating the principle of the present invention, but the present invention is not limited thereto. For those skilled in the art, various modifications and improvements can be made without departing from the spirit and essence of the present invention, and these modifications and improvements are also regarded as the protection scope of the present invention.

Claims (6)

1. an organic electroluminescence device, including anode layer, hole injection layer, hole Transport layer, organic luminous layer, electron transfer layer, electron injecting layer and cathode layer, described Organic luminous layer includes material of main part, for luminous guest materials, it is characterised in that Described organic luminous layer also includes the adulterant for adjusting electric charge transmission；

Described material of main part is electric transmission shaped material, and described adulterant is hole-transporting type Material；Or

Described material of main part is hole transport shaped material, and described adulterant is electron-transporting type Material；

Described adulterant relative to the mass percent of described material of main part along hole transport Layer is increased or decreased to the direction doping content of electron transfer layer.

2. organic electroluminescence device as claimed in claim 1, it is characterised in that institute The adulterant stated is linearly increasing relative to the mass percent of described material of main part or linearly drops Low, or gradient increases or gradient reduces.

3. organic electroluminescence device as claimed in claim 1, it is characterised in that institute The hole transport shaped material stated is selected from N, N'-diphenyl-N, N'-(1-naphthyl)-1,1'-biphenyl -4,4'-diamidogen, 4,4'-bis-(9-carbazole) biphenyl, 4,4'-bis-(2,2-diphenylethyllenes)-1,1'-biphenyl, Any one in 5,6,11,12-tetraphenyl aphthacene.

4. organic electroluminescence device as claimed in claim 1, it is characterised in that institute The electric transmission shaped material stated is selected from three (8-hydroxyquinoline) aluminum, 1,3,5-tri-(1-phenyl-1H- Benzimidazolyl-2 radicals-yl) benzene, 4,7-diphenyl-1, any one in 10-o-phenanthroline.

5. the organic electroluminescence device as described in claim 1-4 is arbitrary, its feature exists In, described adulterant is in terms of 100% by material of main part quality, and adulterant mass percent is 0.1%-30%.

6. an organic electroluminescence display device and method of manufacturing same, it is characterised in that include that right such as is wanted Seek the arbitrary described organic electroluminescence device of 1-5.