CN100593357C - Organic Electroluminescent Devices - Google Patents

Abstract

The invention provides an organic electroluminescent device, which comprises a substrate, an anode formed on the substrate, a first hole injection layer formed on the anode, a second hole injection layer formed on the first hole injection layer, an electroluminescent layer formed on the second hole injection layer and a cathode formed on the electroluminescent layer, wherein the first hole injection layer is made of fluorocarbon, and the second hole injection layer contains P-type dopant.

Description

Organic Electroluminescent Devices

technical field

The invention relates to an organic electroluminescent device, in particular to an organic electroluminescent device using fluorocarbon compound and a hole injection layer doped with P-type dopant.

Background technique

In recent years, with the advancement of electronic product development technology and its increasingly wide application, such as the advent of mobile phones, PDAs and notebook computers, the demand for flat-panel displays with smaller volume and power consumption characteristics compared with traditional displays has increased day by day , has become one of the most important electronic application products at present. Among flat-panel displays, organic electroluminescent devices will become the best choice for next-generation flat-panel displays due to their characteristics such as self-luminescence, high brightness, wide viewing angle, high response speed, and easy manufacturing process.

An organic electroluminescent device is a self-luminous type device using organic materials. 1, a typical organic electroluminescent device 10 includes a substrate 11 and an anode 12, a hole injection layer (hole injection layer) 13, and a hole transport layer (hole transport layer) 14 formed sequentially on the substrate 11 , an organic light emitting layer (emissive layer) 15, an electron transport layer (electron transport layer) 16 and a cathode 17.

The light-emitting principle of the organic electroluminescent device 10 is: electrons are injected through the cathode 17, holes are injected into the anode 12, and the potential difference generated by an external electric field is used to promote these electrons and holes to move to the organic light-emitting layer 15 for recombination. (recombination) to achieve the purpose of luminescence.

When electrons and holes move from the electrodes (such as the anode 12 and the cathode 17) to the organic light-emitting layer 15 for recombination, the above-mentioned carriers (carriers) must overcome the energy barrier existing at the interface (interface) between the layers. (energy barriers). Taking the anode side as an example, the carriers (holes) must overcome between the anode 12 and the hole injection layer 13, between the hole injection layer 13 and the hole transport layer 14, and between the hole transport layer 14 and the organic light-emitting layer. The energy barrier existing at the interface between 15; when a larger energy barrier exists at the interface of the above-mentioned layers, carriers (holes) are less likely to enter the organic light-emitting layer 15, and will be at the interface of each layer. Buildup occurs at the interface, which, in turn, leads to an increase in device operating voltage and a decrease in device lifetime.

In order to avoid the rise of the operating voltage of the device, the traditional method is to reduce the thickness of the organic film between the anode 12 and the organic light-emitting layer 15, but the thinner the organic film, the lower the efficiency of the device, the lower the stability, and the easy formation of short circuits. And many other shortcomings.

In the manufacturing process of organic electroluminescent devices, the residue of particles can easily lead to the short circuit of pixels and form dark spots. However, even in a clean room, no matter how clean the panel or other equipment is, there will still be a small amount of particles The existence of other pollutants, such as other pollutants, will cause a short circuit of the pixel, making it unable to function normally, and affecting the luminous efficiency of the device, the life of the device and the yield of the process. The particle problem has always been one of the main reasons why organic electroluminescent displays cannot be mass-produced and enlarged.

Please continue to refer to FIG. 1. In the structure of a general organic electroluminescent device 10, the total thickness of the hole injection layer 13 plus the hole transport layer 14 is about 80-170 nanometers. There are a small number of small particles in the environment, but the problems caused by generally larger particles cannot be avoided.

In order to solve the above-mentioned problems caused by particles, panel manufacturers must spend huge manpower, material resources and financial resources to update equipment or clean panels and machines. The cost is expensive, but the effect is limited.

US Patent US 6,849,345 discloses an OLED structure, which promotes the luminous efficiency of OLEDs by developing new hole transport layer materials.

US Patent US 6,841,267 discloses an OLED structure, which promotes the luminous efficiency and device life of OLEDs by developing new luminescent doping materials.

US Patent No. 6,818,329 discloses an OLED structure, which improves the luminous efficiency of the OLED by inserting a metal layer between the hole transport layers.

U.S. Patent No. 6,692,846 discloses a kind of OLED structure, and it forms two-layer hole-transporting layer, wherein one layer is doped with stabilizing dopant (stabilizing dopant), another layer is not doped with stabilizing dopant, thereby improves OLED device lifetime.

US Patent No. 6,208,077 discloses an OLED structure, which increases the operational stability of the device by forming a polymer layer made of fluorocarbon between the hole transport layer and the anode.

However, none of the technical contents disclosed in the above-mentioned patents can effectively solve the above-mentioned shortcomings. Therefore, how to improve the above-mentioned shortcomings is a problem that the industry needs to overcome.

Contents of the invention

In view of this, the present invention provides an organic electroluminescent device. The organic electroluminescent device in the embodiment of the present invention comprises a substrate, an anode formed on the substrate, a first hole injection layer formed on the anode, a A second hole injection layer on the first hole injection layer, an electroluminescent layer formed on the second hole injection layer, and a cathode formed on the electroluminescent layer, wherein the first hole injection layer is It is made of fluorocarbon, and the second hole injection layer contains P-type dopant.

In order to make the above-mentioned purposes, features and advantages of the present invention more obvious and understandable, the preferred embodiments are specifically listed below, and in conjunction with the accompanying drawings, the detailed description is as follows:

Description of drawings

FIG. 1 illustrates a conventional organic electroluminescent device.

Fig. 2a is an organic electroluminescence device according to an embodiment of the present invention.

Fig. 2b is an organic electroluminescent device according to another embodiment of the present invention.

FIG. 3a shows the relationship between luminance and operating voltage.

Fig. 3b is a graph showing the relationship between luminous efficiency and luminance.

Explanation of reference signs

10, 20a, 20b ~ organic electroluminescent devices;

11, 21 ~ substrate;

12, 22 ~ anode;

13～hole injection layer;

14, 25～hole transport layer;

15, 26～organic light-emitting layer;

16, 27 ~ electron transport layer;

17, 28 ~ cathode;

23～the first hole injection layer;

24～second hole injection layer;

29～the third hole injection layer;

A, B, C, D ~ curve.

Detailed ways

According to different product requirements, it may be necessary to form organic electroluminescent devices with different hole injection layer thicknesses. Therefore, the purpose of an embodiment of the present invention is to improve the effect of hole injection by using fluorocarbons and a hole injection layer doped with P-type dopants at the same time, so that even if the device adds an organic light-emitting layer and an anode The thickness of the organic film between them can also effectively prevent the operating voltage of the device from rising, thereby improving the life of the device.

The purpose of another embodiment of the present invention is to reduce the impact of particles in the process environment on the organic electroluminescent device by increasing the thickness of the organic film between the organic light-emitting layer and the anode, thereby improving mass production and large-scale possibility and reliability (reliability), while effectively avoiding an increase in the operating voltage of the device.

Please refer to FIG. 2a. FIG. 2a is an organic electroluminescence device 20a illustrated according to an embodiment of the present invention. The hole injection layer 23, the second hole injection layer 24, the hole transport layer 25, the organic light-emitting layer 26, the electron transport layer 27 and the cathode 28, by applying a potential difference between the cathode 28 and the anode 22, electrons and holes The holes are respectively injected into the organic light-emitting layer 26 from the cathode 28 and the anode 22 to recombine to achieve the purpose of emitting light.

In an embodiment of the present invention, the organic electroluminescent device 20a can be manufactured by the following steps.

First, the substrate 21 with the anode 22 is subjected to ultraviolet ozone (ultraviolet ozone) treatment to decompose organic matter on the surface of the substrate 21 and the anode 22 to achieve a cleaning effect.

Then, in the presence of trifluoromethane (CHF ₃ ) and oxygen, a first hole injection layer made of fluorocarbon is deposited on the anode 22 by chemical vapor deposition. 23, the thickness of which is approximately between 1-10 nanometers.

Then, a second hole injection layer 24 with a thickness of tens to hundreds of nanometers is formed on the first hole injection layer 23 by evaporation, and the second hole injection layer 24 is doped with P -type dopant (P-type dopant), the doping concentration is between 1-25vol% (volume percentage), and the mobility of the second hole injection layer 24 is generally between 10 ⁻³ to 10 ^-6 cm ² V ^-1 s ^-1 .

In one embodiment, the total thickness of the first hole injection layer 23 and the second hole injection layer 24 is approximately between 150-1000 nanometers; in another embodiment, the first hole injection layer 23 and the second hole injection layer The total thickness of the two hole injection layers 24 is about 300-1000 nm.

Then, a hole transport layer 25 with a thickness of about 10-100 nm is formed on the second hole injection layer 24 by evaporation.

Secondly, an organic light-emitting layer 26 with a thickness of about 10-100 nanometers is formed on the hole transport layer 25 by evaporation.

Then, an electron transport layer 27 with a thickness of about 10-100 nanometers is formed on the organic light-emitting layer 26 by evaporation.

Next, the cathode 28 is formed on the above-mentioned electron transport layer 27 by vapor deposition, which is composed of lithium fluoride (LiF) with a thickness of about 1 nanometer and aluminum (Al) with a thickness of about 100 nanometers. Here, fluorine Lithium chloride can be used as the electron injection layer. However, in another embodiment, an electron injection layer (not shown) made of other materials can also be selectively formed between the cathode 28 and the electron transport layer 27 .

Please refer to FIG. 2b. FIG. 2b is an organic electroluminescent device 20b according to another embodiment of the present invention. This organic electroluminescent device 20b includes a substrate 21 and an anode 22 formed on the substrate 21 in sequence, A hole injection layer 23 , a second hole injection layer 24 , a third hole injection layer 29 , a hole transport layer 25 , an organic light emitting layer 26 , an electron transport layer 27 and a cathode 28 . By applying a potential difference between the cathode 28 and the anode 22, electrons and holes are respectively injected from the cathode 28 and the anode 22 into the organic light-emitting layer 26 to recombine to emit light, thereby achieving the purpose of emitting light.

In an embodiment of the present invention, the organic electroluminescent device 20b can be manufactured by steps similar to the above-mentioned organic electroluminescent device 20a, the difference is that the organic electroluminescent device 20b further includes a third hole injection layer 29. Since the manufacturing steps of the remaining layers of the organic electroluminescent device 20b are the same as those of the organic electroluminescent device 20a, details will not be repeated here, and only the third hole injection layer 29 will be described below.

After sequentially forming the substrate 21, the anode 22, the first hole injection layer 23 and the second hole injection layer 24, then, on the second hole injection layer 24, a layer with a thickness of about tens of The third hole injection layer 29 between hundreds of nanometers, the third hole injection layer 29 does not contain P-type dopant. In one embodiment, the total thickness of the first, second and third hole injection layers 23, 24 and 29 is approximately between 150-1000 nanometers; in another embodiment, the first, second and third The total thickness of the three hole injection layers 23 , 24 and 29 is about 300-1000 nm.

Then, a hole transport layer 25 , an organic light emitting layer 26 , an electron transport layer 27 and a cathode 28 are sequentially formed on the third hole injection layer 29 by evaporation to complete the fabrication of the organic electroluminescent device 20 b.

In the above organic electroluminescent devices 20a and 20b, the materials used in each layer are as follows:

The substrate 21 may be a glass substrate, a ceramic substrate, a plastic substrate or a semiconductor substrate. Substrate 21 can be selected from materials as required. For example, if it is desired to form a top-emission organic electroluminescent device, the substrate can be an opaque substrate; if it is desired to form a double-sided emission organic electroluminescent device, the substrate can be transparent substrate.

The anode 22 can be a transparent electrode or a metal electrode, and at least one of its materials can be selected from lithium, magnesium, calcium, aluminum, silver, indium, gold, tungsten, nickel, platinum, indium tin oxide (ITO), indium zinc oxide (IZO), zinc aluminum oxide (AZO), zinc oxide (ZnO), gallium nitride, gallium indium nitride, cadmium sulfide, zinc sulfide, cadmium selenide, and zinc selenide, or combinations of the above materials, and the manner in which they are formed It can be thermal evaporation (thermal evaporation), sputtering (sputtering) or plasma-enhanced chemical vapor deposition (plasma-enhanced chemical vapor deposition).

The first hole injection layer 23 can be made of fluorocarbon, which can be expressed as CF _x H _(4-x) , generally referred to as CF _x .

The second hole injection layer 24 can be selected from CuPc (copper phthalocyanine), m-MTDATA (4,4′,4″-Tris(N-3-methylphenyl-N-phenyl-amino)-triphenylamine, 4,4′ , 4″-tri(N-3-methylphenyl-N-phenyl-amino)-triphenylamine), TPTE (N, N-Bis(4-diphenylaminobiphenyl)-N, N-diphenylbenzidine, N, N-bis(4-diphenylaminobiphenyl)-N,N-p-diaminobiphenyl), NPB: F ₄ -TCNQ(N,N′-diphenyl-N,N′-bis(1-naphthyl )-(1,1'-bisphenyl)-4,4'-diamine: tetrafluoro-tetracyano-quinodimethane, N,N'-diphenyl-N,N'-bis(1-naphthyl)-(1,1 '-biphenyl)-4,4'-diamine: tetrafluoro-tetracyano-quinodimethane), F ₄ -TCNQ: WO ₃ (tetrafluoro-tetracyano-quinodimethane: tungsten oxide), At least one of polymers of the above materials and derivatives of the above materials.

The P-type dopant contained in the second hole injection layer 24 is selected from F ₄ -TCNQ, FeCl ₃ , V ₂ O ₅ , WO ₃ , MoO ₃ , Nb ₂ O ₅ , Ir(OH) ₃ , the above At least one of polymers of materials and derivatives of the above materials.

The third hole injection layer 29 may be composed of the material forming the second hole injection layer 24 above, but it may not contain P-type dopant.

The hole-transporting layer 25 can be made of allylamines or diamine (diamine) derivatives, and the above-mentioned diamine derivatives include NPB, T-PD (N, N'-diphenyl-N, N'-bis(3- methylphenyl)-(1,1′-bisphenyl)-4,4′-diamine; N,N′-diphenyl-N,N′-bis(3-methylphenyl)-(1,1′-linked phenyl)-4,4′-diamine), 1T-NATA (4,4′,4″-tris(N-(1-naphthyl)-N-phenyl-amino)-trisphenyl-amine; 4,4′ , 4″-tris(N-(1-naphthyl)-N-phenyl-amino)-triphenylamine), or 2T-NATA (4,4′,4″-tris(N-(2-naphthyl )-N-phenyl-amino)-trisphenyl-amine; 4,4',4"-tris(N-(2-naphthyl)-N-phenyl-amino)-trisphenylamine).

The organic light-emitting layer 26 can be made of Alq3: C545T, MADN: DSA-ph or other organic light-emitting materials

Constituted, here, Alq3 is Tris (8-hydroxyquinoline) aluminum (three (8-hydroxyquinoline) aluminum), C545T is 1H, 5H, 11H-[1] benzopyran [6, 7, 8, - ij] quinozin-11-one, 10-(2-benzothiazolyl)-2,3,6,7-tetrahydro-1,1,7,7,-tetramethyl-(9CI) (1H, 5H, 11H-[1]Benzopyrano[6,7,8,-ij]quinolizin-11-one,10-(2-benzothiazolyl)-2,3,6,7-tetrahydro-1,1,7,7, -tetramethyl-(9CI)), MADN is 2-(methyl)-9,10-bis(2-naphthyl)anthracene (2-methyl-9,10-di(2-naphthyl)anthracene), DSA-ph It is p-bis (p-N, N-di-phenyl-aminostyryl) benzene (p-bis (p-N, N-di-phenyl-aminostyryl) benzene).

Electron transport layer 27 is selected from Alq3, aluminum complex, metal quinolinate compound (metalquinolinate), oxadiazole (oxadiazole), triazole compound (triazoles), phenanthroline (phenanthroline), the polymer of above-mentioned material and derivatives of the above materials.

The first hole injection layer 23, the second hole injection layer 24, the third hole injection layer 29, the hole transport layer 25, the organic light-emitting layer 26 and the electron transport layer 27 can be made of low-molecular materials or high-molecular materials respectively. , can be formed by vacuum evaporation, spin coating, ink jet or screen printing. In addition, the organic light-emitting layer 26 may include organic electroluminescent materials and dopants, and those skilled in the art may change the properties of the matched dopants depending on the organic electroluminescent materials used and the required device characteristics. Doping amount.

Cathode 28 may be composed of aluminum, aluminum:lithium alloy, magnesium:silver alloy, or other cathode materials.

In the above-mentioned organic electroluminescent devices 20a and 20b, since the second hole injection layer 24 is doped with a P-type dopant, the HOMO (highest occupied molecular orbit, highest occupied molecule) of the second hole injection layer 24 can be improved. Orbit) energy level, which reduces the energy barrier between the second hole injection layer 24 and the hole transport layer 25, and the use of the first hole injection layer 23 (made of fluorocarbons), reduces the anode 22 The energy barrier between the second hole injection layer 24 makes the holes easily pass through the anode 22, pass through the organic films 23, 24 and 25 and reach the organic light-emitting layer 26, so the hole injection effect of the organic electroluminescent device can be improved , to prevent the operating voltage of the device from rising, thereby improving the life of the device.

In addition, since the use of the hole injection layer 24 doped with P-type dopants and the fluorocarbon compound 23 can prevent the operating voltage of the device from rising, therefore, the thickness of the organic films 23, 24 and 25 can be increased to reduce the environmental The impact of the particles in the organic electroluminescent device, and the device still maintains good performance.

Taking FIG. 2b as the main framework, three organic electroluminescent devices with different hole injection layer thicknesses will be listed as examples below, the formation steps will be described in detail, experimental tests will be carried out, and the experimental results will be compared with the experimental results of the comparative example.

comparative example

The organic electroluminescence device of the comparative example can be manufactured by the following steps.

First, the substrate with a 75nm-thick ITO anode is subjected to ultraviolet ozone (ultravioletozone) treatment to decompose the organic matter on the surface of the substrate and the anode to achieve the purpose of cleaning.

Then, form a phenyl amine derivative with a thickness of about 150 nanometers on the anode as a hole injection layer by means of evaporation, and this hole injection layer is doped with 2 vol% of F ₄ -TCNQ as a P-type dopant things.

Then, NPB with a thickness of about 20 nanometers was formed as a hole transport layer on the hole injection layer by evaporation.

Then, Alq3:C545T with a thickness of about 30 nanometers was formed on the hole transport layer by evaporation as an organic light-emitting layer.

Next, Alq3 with a thickness of about 30 nanometers was formed on the organic light-emitting layer by evaporation as an electron transport layer.

Next, lithium fluoride (LiF) with a thickness of about 1 nanometer and aluminum (Al) with a thickness of about 100 nanometers were sequentially formed on the above-mentioned electron transport layer by evaporation as a cathode, and the organic electroluminescent device of the comparative example was completed. production.

Example 1

The organic electroluminescence device of Example 1 can be manufactured by the following steps.

First, the substrate with a 75nm-thick ITO anode is treated with ultraviolet light and ozone to decompose the organic matter on the surface of the substrate and the anode to achieve the purpose of cleaning.

Then, in the presence of trifluoromethane (CHF ₃ ) and oxygen, a film made of fluorocarbon is deposited on the anode by chemical vapor deposition, and this film is the first hole injection layer.

Then, aniline derivatives with a thickness of about 60 nanometers are formed on the first hole injection layer by evaporation as a second hole injection layer, and the second hole injection layer is doped with 2 vol% of F ₄ -TCNQ as P-type dopant.

Next, an aniline derivative with a thickness of about 90 nanometers is formed on the second hole injection layer by evaporation as a third hole injection layer, and the third hole injection layer does not contain P-type dopant.

Then, NPB with a thickness of about 20 nanometers was formed as a hole transport layer on the hole injection layer by evaporation.

Then, Alq3:C545T with a thickness of about 30 nanometers was formed on the hole transport layer by evaporation as an organic light-emitting layer.

Next, Alq3 with a thickness of about 30 nanometers was formed on the organic light-emitting layer by evaporation as an electron transport layer.

Next, lithium fluoride (LiF) with a thickness of about 1 nanometer and aluminum (Al) with a thickness of about 100 nanometers are sequentially formed on the above-mentioned electron transport layer by evaporation as the cathode, and the organic electroluminescence in Example 1 is completed. device fabrication.

Example 2

The organic electroluminescent device of Example 2 can be manufactured by the following steps. It should be noted here that, since the difference between Embodiment 2 and Embodiment 1 is only the formation thickness of the second hole injection layer is different, and the materials and manufacturing methods of the other layers are the same, so it will not be repeated here, only for the second hole injection layer. Two hole injection layers are described.

After forming the ITO anode and the first hole injection layer, aniline derivatives with a thickness of about 150 nanometers are formed as the second hole injection layer on the first hole injection layer made of fluorocarbon by evaporation, The second hole injection layer is doped with 2vol% of F ₄ -TCNQ as a P-type dopant, and then the second hole injection layer is sequentially formed on the second hole injection layer by evaporation and does not contain P-type dopant. The third hole injection layer, hole transport layer, organic light emitting layer, electron transport layer and cathode of the material.

Example 3

The organic electroluminescent device of Example 3 can be manufactured by the following steps. It should be noted here that, since the difference between Embodiment 3 and Embodiment 1 is only the formation thickness of the second hole injection layer is different, and the materials and manufacturing methods of the other layers are the same, so it will not be repeated here, only for the second hole injection layer. Two hole injection layers are described.

After forming the ITO anode and the first hole injection layer, aniline derivatives with a thickness of about 200 nanometers are formed as the second hole injection layer on the first hole injection layer made of fluorocarbon by evaporation, The second hole injection layer is doped with 2vol% of F ₄ -TCNQ as a P-type dopant, and then the second hole injection layer is sequentially formed on the second hole injection layer by evaporation without P-type dopant. The third hole injection layer, hole transport layer, organic light emitting layer, electron transport layer and cathode of the material.

It should be noted here that the above manufacturing steps of the organic electroluminescent device (Example 1, 2 and 3) with the main structure shown in FIG. 2b are for illustration purposes only, and are not intended to limit the present invention. The organic electroluminescent device with the main structure shown in FIG. 2a also has excellent characteristics similar to the embodiment shown in FIG. 2b because it also has a fluorocarbon compound and a hole injection layer containing a P-type dopant.

In addition, in the above-mentioned embodiment 3, the total thickness of the first, second and third hole injection layers is about 300 nanometers, but the present invention is not limited thereto, and in other embodiments, thicker holes can also be used. An injection layer is formed in an organic electroluminescence device.

In addition, in the above embodiments, taking Embodiment 3 as an example, the total thickness of the first, second and third hole injection layers is about 300 nanometers, wherein the thickness of the second hole injection layer is 200 nanometers, and the thickness of the third hole injection layer is about 300 nanometers. The thickness of the hole injection layer is 90 nanometers, but the present invention is not limited thereto. In other embodiments with a total thickness of about 300 nanometers, other second and third hole injection layers with different thicknesses can also be used, so that the total thickness up to 300 nm.

The experimental results of the above-mentioned embodiments and comparative examples are shown in FIGS. 3 a and 3 b. FIG. 3a shows the relationship between luminance and operating voltage; FIG. 3b shows the relationship between luminous efficiency and luminance. Wherein, curves A, B, C and D represent the experimental results of Comparative Example, Example 1, Example 2 and Example 3, respectively.

As shown in Figure 3a, under the same operating voltage, curves A, B, C and D all have almost the same luminance value, and Figure 3b also shows that curves A, B, C and D have very similar luminous efficiencies.

Taking curves A and D (comparative example and embodiment 3) as an example, when the luminance reaches 3000cd/ ^m2 , the operating voltage of curves A and D are both about 6 volts, and the luminous efficiency is both 5.8cd/A Left and right, it shows that the organic electroluminescent device of the present invention can still maintain the same operating performance as the comparative example (150 nanometers) after increasing the total thickness of the hole injection layer to 300 nanometers, for example, the operating voltage will not increase accordingly , and the luminous efficiency will not be reduced, and the organic electroluminescent device of embodiment 3 has the following advantages more than the comparative example:

By using the fluorocarbon compound and the hole injection layer doped with P-type dopants at the same time, the hole injection effect is improved, so that even if the device needs to increase the organic film between the organic light-emitting layer and the anode according to different product requirements Thickness can also effectively prevent the operating voltage of the device from rising, thereby improving the life of the device.

By increasing the thickness of the organic film, even if the particles in the environment settle on the organic film during the manufacturing process, the thicker organic film can also cover the particles, avoiding the short circuit of the pixel and making the pixel unable to function normally, thereby improving The possibility and reliability of mass production and large-scale, while effectively avoiding the rise of the operating voltage of the device.

Although the present invention has been disclosed above with a number of preferred embodiments, it is not intended to limit the present invention. Any person skilled in the art should be able to make various changes and modifications without departing from the spirit and scope of the present invention. Therefore, the protection scope of the present invention should be defined by the appended claims.

Claims (12)

1. An organic electroluminescence device, comprising: Substrate; an anode formed on the substrate; a first hole injection layer formed on the anode, wherein the first hole injection layer is made of fluorocarbon; a second hole injection layer formed on the first hole injection layer, wherein the second hole injection layer contains a P-type dopant; a third hole injection layer formed on the second hole injection layer, and the third hole injection layer does not contain P-type dopant; an electroluminescent layer formed on the third hole injection layer; and The cathode is formed on the electron transport layer. 2. The organic electroluminescent device as claimed in claim 1, wherein the electroluminescent layer comprises a hole transport layer, an organic light emitting layer and an electron transport layer, the hole transport layer is formed on the third hole injection layer, and the organic light emitting layer The layer is formed on the hole transport layer, and the electron transport layer is formed on the organic light emitting layer. 3. The organic electroluminescence device of claim 1, further comprising an electron injection layer formed between the electroluminescence layer and the cathode. 4. The organic electroluminescence device according to claim 1, wherein the mobility of the second hole injection layer is between 10 ⁻³ and 10 ⁻⁶ cm ² V ⁻¹ s ⁻¹ . 5. The organic electroluminescence device as claimed in claim 1, wherein the thickness of the first hole injection layer is between 1-10 nanometers. 6. The organic electroluminescence device as claimed in claim 1, wherein the material of the second hole injection layer is selected from copper phthalocyanine, 4,4', 4 "-three (N-3-methylphenyl-N -Phenyl-amino)-triphenylamine, N,N-bis(4-diphenylaminobiphenyl)-N,N-p-diaminobiphenyl, N,N'-diphenyl-N, N'-bis(1-naphthyl)-(1,1'-biphenyl)-4,4'-diamine: tetrafluoro-tetracyano-quinodimethane, tetrafluoro-tetracyano-quinone di Methane: tungsten oxide, polymers of the above materials and derivatives of the above materials. 7. The organic electroluminescent device as claimed in claim 1, wherein the P-type dopant is selected from tetrafluoro-tetracyano-quinodimethane, FeCl ₃ , V ₂ O ₅ , WO ₃ , MoO ₃ , Nb ₂ O ₅ , Ir(OH) ₃ , polymers of the above materials, and derivatives of the above materials. 8. The organic electroluminescent device of claim 1, wherein the first hole injection layer is immediately adjacent to the second hole injection layer. 9. The organic electroluminescent device as claimed in claim 1, wherein the concentration of the P-type dopant is between 1-25 vol%. 10. The organic electroluminescent device as claimed in claim 1, wherein the total thickness of the first, second and third hole injection layers is between 150-1000 nm. 11. The organic electroluminescent device as claimed in claim 1, wherein the total thickness of the first, second and third hole injection layers is between 300-1000 nm. 12. The organic electroluminescent device as claimed in claim 1, wherein the material of the third hole injection layer is selected from copper phthalocyanine, 4,4', 4"-three (N-3-methylphenyl-N -Phenyl-amino)-triphenylamine, N,N-bis(4-diphenylaminobiphenyl)-N,N-p-diaminobiphenyl, N,N'-diphenyl-N, N'-bis(1-naphthyl)-(1,1'-biphenyl)-4,4'-diamine: tetrafluoro-tetracyano-quinodimethane, tetrafluoro-tetracyano-quinone di Methane: tungsten oxide, polymers of the above materials and derivatives of the above materials.

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