CN108963094B

CN108963094B - Organic electroluminescent device

Info

Publication number: CN108963094B
Application number: CN201810763668.XA
Authority: CN
Inventors: 李育豪; 王君; 于倩倩; 谢静; 朱映光; 郭立雪; 胡永岚
Original assignee: Guan Yeolight Technology Co Ltd
Current assignee: Guan Yeolight Technology Co Ltd
Priority date: 2018-07-12
Filing date: 2018-07-12
Publication date: 2020-06-09
Anticipated expiration: 2038-07-12
Also published as: CN108963094A

Abstract

The application discloses an organic electroluminescent device, which comprises a substrate, a first electrode, an organic layer, a second electrode and a packaging structure which are sequentially arranged; the organic layer comprises a light-emitting layer, a hole transmission functional layer and an electron transmission functional layer which are positioned on two sides of the light-emitting layer; a UV sacrificial layer is arranged between the electrode corresponding to the light-emitting surface of the light-emitting device and the light-emitting layer, and the UV sacrificial layer contains a light-absorbing material; a first additional functional layer for avoiding electroluminescence is arranged between the UV sacrificial layer and the luminescent layer. According to the OLED device, the UV sacrificial layer is arranged inside the light-emitting device, so that the OLED device has the capability of resisting high-energy light rays, the reliability and the service life of OLED related products are greatly improved, and the application space can be increased.

Description

Organic electroluminescent device

Technical Field

The present disclosure relates generally to the field of lighting, and more particularly to the field of OLED lighting.

Background

The OLED (Organic Light Emitting Diode) refers to a phenomenon that an Organic semiconductor material and a Light Emitting material emit Light by carrier injection and recombination under electric field driving. The principle is that a transparent/semitransparent metal/metal oxide electrode and a metal/metal oxide electrode are respectively used as an anode and a cathode of the device, carriers (electrons and holes) are respectively injected into an electron and hole transmission functional layer from the cathode and the anode under the drive of an external electric field, the electrons and the holes are respectively transmitted to a light-emitting layer through the electron and hole transmission functional layer, excitons (exiton) are formed in a light-emitting material, limited electrons and holes in the excitons disappear after recombination, and energy is radiated in the form of visible light (the light-emitting wavelength is limited by the characteristics of the light-emitting material). The radiated light can be observed from the transparent/translucent electrode side. This light-emitting principle is used in a large number of applications in lighting and display screens.

However, most organic materials are sensitive to high-energy light, and the high-energy light source mainly existing in the general environment is energy with luminous energy mainly falling in 2.8-4.1 electron volts; some materials in the OLED device may be attenuated by a high-energy light source in the environment, and the attenuation rule is: the product of the illumination intensity of the high-energy light source and the illumination time value is close to a fixed value. The decay to a certain ratio of the source-starting brightness for OLED lighting applications is defined as the lifetime of the OLED lighting, and if the OLED device (such as automotive or aircraft lighting) is heavily illuminated by high-energy light, the high-energy light source therein can accelerate the aging of the screen body and shorten the lifetime of the screen body.

All designs for blocking the high-energy light source outside the screen body all reduce the deterioration of the device when the high-energy light source enters the OLED device, for example, the service life of the OLED screen body can be prolonged by using an external lamp shell, an anti-ultraviolet material, a reflecting layer and the like.

The design of blocking the high-energy light source influences the attractiveness of the OLED device to a certain extent, and the cost of the OLED device is increased.

Disclosure of Invention

In view of the above-mentioned drawbacks or deficiencies in the prior art, it is desirable to provide an organic electroluminescent device that can substantially improve the resistance of the OLED device itself to irradiation by a high-energy light source without affecting the design of the device.

The first aspect of the present application provides an organic electroluminescent device, including a substrate, a first electrode, an organic layer, a second electrode, and an encapsulation structure, which are sequentially stacked; the light emitting surface of the organic electroluminescent device is positioned on one side of the first electrode or the second electrode; the organic layer comprises a light-emitting layer, a hole transmission functional layer and an electron transmission functional layer, wherein the hole transmission functional layer and the electron transmission functional layer are positioned on two sides of the light-emitting layer; a UV sacrificial layer is arranged between the first electrode or the second electrode where the light emitting surface of the light emitting device is located and the light emitting layer, and a first additional functional layer used for avoiding electroluminescence is arranged between the UV sacrificial layer and the light emitting layer.

According to the technical scheme provided by the embodiment of the application, the UV sacrificial layer is formed by doping a light absorption material by taking a hole transmission functional layer or an electron transmission functional layer as a doping main body.

According to the technical scheme provided by the embodiment of the application, the light absorption material is any one of a fluorescent material, a phosphorescent material or a quantum dot.

According to the technical scheme provided by the embodiment of the application, the hole transport function layer is formed by layering at least one of a hole injection layer HI, a hole transport layer HT or an electron blocking layer EBL; the electron transport function layer is formed by layering at least one of an electron injection layer EI, an electron transport layer ET and a hole blocking layer HBL.

According to the technical scheme provided by the embodiment of the application, the first additional functional layer is made of a main body material of the UV sacrificial layer, and the thickness of the first additional functional layer is larger than or equal to 10 nm.

According to the technical scheme provided by the embodiment of the application, the UV sacrificial layer can absorb the light rays with the luminous energy larger than that of the luminous layer and smaller than 3.0 eV.

According to the technical scheme provided by the embodiment of the application, the thickness of the UV sacrificial layer is greater than or equal to 20 nm.

According to the technical scheme provided by the embodiment of the application, the weight ratio of the light absorbing material in the UV sacrificial layer ranges from 1% to 5%.

According to the technical scheme provided by the embodiment of the application, a second additional functional material for improving the charge transport capability is mixed in the UV sacrificial layer.

According to the technical scheme provided by the embodiment of the application, the second additional functional material is any one of metal, metal oxide, carbon material and organic semiconductor material with extremely strong electron affinity or free ability.

According to the OLED device, the UV sacrificial layer is arranged in the light emitting device (the OLED device), so that the OLED device has the capability of resisting high-energy light rays, the reliability and the service life of related products of the OLED are greatly improved, and the application space can be increased. The UV sacrificial layer is arranged in the hole transmission functional layer or the electron transmission functional layer, and particularly, when the UV sacrificial layer is the technical scheme that the hole transmission functional layer or the electron transmission functional layer is doped with light absorption materials, the technical scheme of the application can improve the capability of absorbing high-energy light of the OLED device on the premise of not influencing the structure and the production process of the original OLED device;

the utility model provides a extinction material in UV sacrificial layer is mainly selected from luminous dyestuff, it is general convenient to select the material, the influence to former OLED device efficiency is below 15%, but this layer is to the absorption of high energy light, can slow down the rising speed of OLED screen body voltage after long-time high energy light shines, the voltage rise to the culmination that makes OLED screen body after the high energy light shines is lower, because of OLED screen attenuation effect characterizes for luminance decline and voltage rise on photoelectric property descends, consequently, the peak that slows down the rising speed of voltage and voltage rise just equals can increase screen body life, the experiment shows that the technical scheme of this application makes the life of screen body improve at least 30%.

According to the invention, the first additional functional layer is arranged between the UV sacrificial layer and the luminous layer, so that electroluminescence can be effectively avoided, and especially when the additional functional layer is prepared from a UV sacrificial layer main body material, the effect is better, and the process is simpler.

According to the UV sacrificial layer, the second additional functional material is added into the UV sacrificial layer, so that the charge transmission capability of the UV sacrificial layer can be effectively improved, the voltage of a device is reduced, the carrier mobility is prolonged, the service life is prolonged, and meanwhile, the electroluminescence phenomenon of the UV sacrificial layer can be reduced.

Drawings

Other features, objects and advantages of the present application will become more apparent upon reading of the following detailed description of non-limiting embodiments thereof, made with reference to the accompanying drawings in which:

FIG. 1 is a schematic structural diagram of a first embodiment of an organic electroluminescent device of the present application;

FIG. 2 is a schematic structural diagram of a second embodiment of an organic electroluminescent device of the present application;

FIG. 3 is a schematic structural view of a third embodiment of an organic electroluminescent device of the present application;

FIG. 4 is a schematic structural view of a fourth embodiment of an organic electroluminescent device of the present application;

FIG. 5 is a schematic structural diagram of a fifth embodiment of an organic electroluminescent device of the present application;

FIG. 6 is a graph of the instantaneous current and voltage trends of the control group versus experimental group 1 and experimental group 2 in the present application;

FIG. 7 is a graph comparing device lifetimes for control versus experiment 1 and experiment 2 in the present application;

reference numbers in the figures: 10. a substrate; 20. a first electrode; 30. a hole transport functional layer; 60. a second electrode; 40. a light emitting layer; 50. an electron transport functional layer; 32. a hole transport layer HT; 31. a hole injection layer HI; 33. a UV sacrificial layer; 52. an electron injection layer EI; 51. an electron transport layer ET; 70. a first additional functional layer; 80 second additional functional material.

Detailed Description

The present application will be described in further detail with reference to the following drawings and examples. It is to be understood that the specific embodiments described herein are merely illustrative of the relevant invention and not restrictive of the invention. It should be noted that, for convenience of description, only the portions related to the present invention are shown in the drawings.

It should be noted that the embodiments and features of the embodiments in the present application may be combined with each other without conflict. The present application will be described in detail below with reference to the embodiments with reference to the attached drawings.

Fig. 1 is a schematic structural diagram of an embodiment of an organic electroluminescent device according to the present application, including a substrate 10, a first electrode 20, an organic layer, a second electrode 60, and an encapsulation structure (not shown) stacked in sequence; the organic layer includes a light emitting layer 40, a hole transport functional layer 30 and an electron transport functional layer 50 on both sides of the light emitting layer 40; a UV sacrificial layer is disposed between the first electrode 20 or the second electrode 60 where the light emitting surface of the organic electroluminescent device is located and the light emitting layer 40, and a first additional functional layer 70 for avoiding electroluminescence is disposed between the UV sacrificial layer and the light emitting layer 40. The hole transport functional layer 30 may be made of a material capable of hole transport, for example, a P-type hole transport layer, and the electron transport functional layer 50 may be made of a material capable of electron transport, for example, an N-type electron transport layer.

The organic electroluminescent device is an OLED luminescent device; the OLED light emitting device has a bottom surface emission type, as shown in fig. 1 and 2, that is, light emission from the first electrode 20 side, and also has a top surface emission type, as shown in fig. 3 and 4, that is, light emission from the second electrode side 60; the arrow direction in the drawing is a light emitting direction, and the organic layer between the first electrode 20 and the second electrode 60 may be a PIN structure, as shown in fig. 1 and 3; or NIP structure, as shown in FIG. 2 and FIG. 4; i.e. the OLED light emitting device may be of four configurations between fig. 1 to 4, whichever the configuration is, a UV sacrificial layer (provided within the structural layer in which the slopes are drawn) is provided between the light emitting face and the light emitting layer 40.

The hole transport function layer may be composed of at least one of a hole injection layer HI, a hole transport layer HT, and an electron blocking layer EBL, and the electron transport function layer may be composed of at least one of an electron injection layer EI, an electron transport layer ET, and a hole blocking layer HBL;

in the embodiment shown in fig. 5, the hole transport functional layer 30 is composed of a hole injection layer HI 31, a hole transport layer HT32, and a hole blocking layer HBL, and the UV sacrificial layer 33 is composed of a hole blocking layer HBL doped with a light absorbing material; the UV sacrificial layer 33 is disposed between the light emitting layer 40 and the hole transport layer HT 32; the electron transport functional layer 50 is composed of an electron injection layer 52 and an electron transport layer 51;

preferably, the UV sacrificial layer is doped with a light-absorbing material by taking a hole transport functional layer or an electron transport functional layer as a doping main body; in other embodiments, a layer of light absorbing material may also be interposed between the light emitting layer and the adjacent layering of hole transporting functional layers or electron transporting functional layers.

The definition of the UV sacrificial layer of the present application is therefore: a layer of a hole transport functional layer doped with a light absorbing material or a layer of an electron transport functional layer doped with a light absorbing material or a layer of a hole transport functional layer adjacent to a light absorbing material layer and a layer of a light absorbing material or a layer of an electron transport functional layer adjacent to a light absorbing material layer and a layer of a light absorbing material layer.

In order to avoid the situation, a body material which is the same as the UV sacrificial layer is placed between the UV sacrificial layer and the light emitting layer to be separated, that is, the first additional functional layer 70 is made of the body material of the UV sacrificial layer; this ensures that only a single type of carrier (electron or hole) is present in the UV sacrificial layer, thereby avoiding electroluminescence.

The first additional functional layer 70 is made of the main material of the UV sacrificial layer or the functional similar material, and the concept of the same main material is as follows:

if the light absorbing material is doped in the hole transport layer HT of the hole transport functional layer or if the light absorbing material layer is adjacent to the hole transport layer HT, the material of the first additional functional layer 70 may be a material capable of performing the hole transport function, and may be, for example, different types of HT, such as HT1, HT2, or HT3 … …;

if the light absorbing material is doped in the hole injection layer HI 31 of the hole transport functional layer or the light absorbing material layer is adjacent to the hole injection layer HI 31, the material of the first additional functional layer 70 may be a material capable of realizing the hole injection function;

if the light absorbing material is doped in the electron blocking layer EBL of the hole transport functional layer or the light absorbing material layer is adjacent to the electron blocking layer EBL, the material of the first additional functional layer 70 may be a material that can realize the electron blocking function;

if the light absorbing material is doped in the electron injection layer EI of the electron transport functional layer or the light absorbing material layer is adjacent to the electron injection layer EI, the material of the first additional functional layer 70 may be a material capable of performing an electron injection function;

if the light absorbing material is doped in the electron transport layer ET of the electron transport functional layer or the light absorbing material layer is adjacent to the electron transport layer ET, the material of the first additional functional layer 70 may be a material capable of realizing the electron transport function;

if the light absorbing material is doped in the hole blocking layer HBL of the electron transport functional layer or the light absorbing material layer is adjacent to the hole blocking layer HBL, the material of the first additional functional layer 70 may be a material that can achieve a hole blocking function;

therefore, when the UV sacrificial layer is disposed on the hole transport functional layer, the following cases may be, and are not limited to, the following table 1:

serial number	Distribution of organic layers (diagonal bars separate layers from layer to layer)
		1	HT 1: light absorbing material/HT 1/light emitting layer/ET
2	HT 1: light absorbing material/HT 2/light emitting layer/ET
		3	EBL: light absorbing material/EBL/light emitting layer/ET
4	HI/HT: light absorbing material/HT/light emitting layer/ET
		5	HT/EBL: light absorbing material/EBL/light emitting layer/ET
6	HI/HT/EBL: light absorbing material/EBL/light emitting layer/ET

TABLE 1

As shown in table 1, the light absorbing material may be blended within the layer; as shown in table 2 below, the light absorbing material may form a layer alone on the surface of the layer.

TABLE 2

The following table 3 shows the composition comparison of the organic layers in several examples of the present application:

experimental group	Composition of layers of organic layer
		Control group	HI/HT (40 nm)/light-emitting layer/ET
Experimental group
	1	HI/HT Yellow dock (20nm)/HT (20 nm)/light emitting layer/ET
Experimental group
	2	HI/HT (17nm)/Yellow dock (3nm)/HT (20 nm)/light emitting layer/ET

TABLE 3

The contrast group is a layer group structure of an organic layer in the prior art, and the experimental group 1 is formed by mixing a yellow fluorescent material in an HT layer in the contrast group; the experimental group 2 was a control group in which a layer of yellow fluorescent material was disposed on the surface of the HT layer. As shown in fig. 6 and 7 and table 4, after the UV sacrificial layer is provided, the electrical parameters of the screen body are relatively close to those of the control group, but the service life of the screen body is remarkably improved.

TABLE 4

The light absorbing material in the above embodiments is a material that can absorb light with a light emission energy greater than that of the light emitting layer and less than 3.0 eV; for example, in a green device with a light-emitting spectrum falling within 550nm, the light-absorbing material can be a material with a light-emitting characteristic between 413nm and 550 nm;

the light absorbing material may be any of a fluorescent material, a phosphorescent material, or a quantum dot. Preferably, the thickness of the first additional functional layer is greater than or equal to 10 nm.

The thickness of the UV sacrificial layer is 20nm or more, and in other embodiments, the thickness of the UV sacrificial layer may be other values of 20nm or more.

Preferably, the light absorbing material in the above embodiment is 20% by weight of the UV sacrificial layer, and in other embodiments, the ratio may be other values in the range of 1% -5%.

As shown in fig. 5, it is preferable that the UV sacrificial layer is mixed with a second additional functional material 80 for enhancing the charge transport ability, such as any one of a metal, a metal oxide, a carbon material, or an organic semiconductor material with very strong electron affinity or free ability. The metal may be, for example, lithium, aluminum, silver, gold, cesium, etc., and the metal oxide may be, for example, molybdenum oxide, tungsten oxide, aluminum oxide, etc.; the carbon material can be, for example, carbon nanotube, fullerene, graphene; the organic semiconductor material having an extremely strong electron affinity or free energy may be F4-TCNQ, Liq (8-hydroxy-quinotorium) or the like, or a doped material. F4-TCNQ has chemical formula of tetracyanoldimethylp-benzoquinone; liq is 8 hydroxyquinoline lithium.

For example, an experimental group 3 is added on the basis of the above table 3, and the components of each layer of the organic layer in the experimental group 3 are as follows:

HI/HT Yellow company F4-TCNQ (20nm)/HT (20 nm)/light-emitting layer/ET;

the above experimental group 3 was blended with F4-TCNQ based on the experimental group 2, and the following Table 5 shows a comparison of the screen electrical parameters of the experimental group 1 and the experimental group 3,

TABLE 5

From the above experimental results, it can be seen that the voltage of the same luminance is much reduced after blending the second additional functional material F4-TCNQ.

Fig. 7 is a graph of device lifetimes for the control group versus the experimental group 1 and the experimental group 2, where the graph is for long time illumination under specific luminance conditions and the luminance rate decreases at different times, and the ordinate is the luminance value in fig. 7. it can be seen from fig. 7 that the luminance in both experimental group 1 and the experimental group 2 is brighter than the control group at the same time, which illustrates that the luminance decay for the experimental group 1 and the experimental group 2 is slower than the control group, i.e., the service lives of the experimental group 1 and the experimental group 2 are longer than the control group.

The above description is only a preferred embodiment of the application and is illustrative of the principles of the technology employed. It will be appreciated by a person skilled in the art that the scope of the invention as referred to in the present application is not limited to the embodiments with a specific combination of the above-mentioned features, but also covers other embodiments with any combination of the above-mentioned features or their equivalents without departing from the inventive concept. For example, the above features may be replaced with (but not limited to) features having similar functions disclosed in the present application.

Claims

1. An organic electroluminescent device comprises a substrate, a first electrode, an organic layer, a second electrode and a packaging structure which are sequentially stacked; the light emitting surface of the organic electroluminescent device is positioned on one side of the first electrode or the second electrode; the organic layer comprises a light-emitting layer, a hole transmission functional layer and an electron transmission functional layer, wherein the hole transmission functional layer and the electron transmission functional layer are positioned on two sides of the light-emitting layer; the light-emitting device is characterized in that a UV sacrificial layer is arranged between a first electrode or a second electrode where a light-emitting surface of the light-emitting device is located and a light-emitting layer, and a hole transmission function layer or an electron transmission function layer is used as a doping main body for doping a light-absorbing material in the UV sacrificial layer; a first additional functional layer for avoiding electroluminescence of the UV sacrificial layer is arranged between the UV sacrificial layer and the luminous layer; the first additional functional layer is made of a main body material of the UV sacrificial layer; the light absorption material is any one of a fluorescent material, a phosphorescent material or a quantum dot.

2. The organic electroluminescent device according to claim 1, wherein the hole transport functional layer is composed of at least one of a hole injection layer HI, a hole transport layer HT, or an electron blocking layer EBL in a layered manner; the electron transport function layer is formed by layering at least one of an electron injection layer EI, an electron transport layer ET and a hole blocking layer HBL.

3. The organic electroluminescent device according to claim 1, characterized in that; the thickness of the first additional functional layer is greater than or equal to 10 nm.

4. The organic electroluminescent device as claimed in claim 1, wherein the UV sacrificial layer can absorb light having a luminous energy greater than that of the light emitting layer and less than 3.0 eV.

5. The organic electroluminescent device according to claim 1, wherein the thickness of the UV sacrificial layer is 20nm or more.

6. The organic electroluminescent device of claim 1, wherein the light absorbing material is present in the sacrificial UV layer in an amount ranging from 1% to 5% by weight.

7. The organic electroluminescent device as claimed in claim 1, wherein a second additional functional material for enhancing charge transport ability is mixed in the UV sacrificial layer.

8. The organic electroluminescent device as claimed in claim 7, wherein the second additional functional material is any one of a metal, a metal oxide, a carbon material, and an organic semiconductor material having a very strong electron affinity or dissociation ability.