CN109686847B

CN109686847B - High efficiency organic light emitting diode device

Info

Publication number: CN109686847B
Application number: CN201710969553.1A
Authority: CN
Inventors: 周卓煇
Original assignee: Individual
Current assignee: Individual
Priority date: 2017-10-18
Filing date: 2017-10-18
Publication date: 2021-02-19
Anticipated expiration: 2037-10-18
Also published as: CN109686847A

Abstract

The invention develops and provides a high-efficiency organic light-emitting diode, which comprises the following basic components: an anode substrate, a hole transport layer, at least one light emitting layer, an electron transport layer, and a cathode layer. In the high-efficiency organic light-emitting diode, the LUMO energy levels of the hole transport layer, the light-emitting layer and the electron transport layer form a step energy level; meanwhile, the HOMO energy levels of the hole transport layer, the light emitting layer and the electron transport layer form a step-type energy level. In addition, the electron mobility of the electron transport layer of the high-efficiency organic light-emitting diode is at least two orders of magnitude higher than that of the light-emitting layer. It should be noted that, as proved by a plurality of experimental data, the organic light emitting diode satisfying the above three conditions can certainly exhibit excellent photoelectric efficiency, which is a high efficiency organic light emitting diode device defined in the present invention.

Description

High efficiency organic light emitting diode device

Technical Field

The present invention relates to the field of light emitting devices, and more particularly, to a high efficiency organic light emitting diode device.

Background

Organic Light Emitting Diodes (OLEDs) were originally proposed by kodak corporation. Tang and VanSlyke respectively plate a hole transport material and an electron transport material, such as Alq3, on ITO glass by vacuum evaporation, and then evaporate a metal electrode, thereby completing the fabrication of an Organic Light Emitting Diode (OLED) having self-luminescence, high brightness, high speed response, light weight, thin thickness, low power consumption, wide viewing angle, flexibility, and full color.

Fig. 1 shows a structure diagram of a conventional organic light emitting diode. In the prior art, a dielectric layer such as an electron transport layer and a hole transport layer is usually added between an anode and a cathode of an organic light emitting diode, so as to increase the current efficiency or power efficiency of the organic light emitting diode. For example, the organic light emitting diode 1' shown in fig. 1 structurally includes: a cathode 11 ', an Electron Transport Layer (ETL) 13 ', an Emission layer (EML) 14 ', a Hole Transport Layer (HTL) 15 ', and an anode 18 '. Also, according to the disclosure of U.S. patent publication No. US2009/0208776A1, we can see that a suitable material for the electron transport layer 13' must have the following physical properties: (1) the Lowest Unoccupied Molecular Orbital level (LUMO level) must be shallower than the LUMO level of the fabrication material of the light-emitting layer 14 ' to achieve efficient injection of electrons from the cathode 11 ' into the light-emitting layer 14 '; and (2) the Highest Occupied Molecular Orbital (HOMO level) must be deeper than the HOMO level of the material from which the light-emitting layer 14 'is made to block the loss of holes from within the light-emitting layer 14'.

Engineers long involved in the design and fabrication of organic light emitting diodes can further infer from the teachings of U.S. patent publication No. US2009/0208776a1 that suitable materials for fabrication of the hole transport layer 15' must have the following physical properties: (1) the highest occupied molecular orbital level (HOMO level) of the material from which the light-emitting layer 14 'is made must be deeper than the HOMO level of the material from which the hole-transporting layer 15' is made to achieve efficient injection of holes from the anode 18 'into the light-emitting layer 14'; and (2) the lowest unoccupied molecular orbital level (LUMO level) of the material from which the light-emitting layer 14 ' is made must be shallower than the LUMO level of the material from which the hole-transporting layer 15 ' is made to block the loss of electrons from the light-emitting layer 14 '.

The present inventors have completed a sample of three sets of organic light emitting diode devices by utilizing the teaching of the prior art document and the basic design knowledge thereof. Fig. 2A, fig. 2B and fig. 2C show energy level structure diagrams of sample a, sample B and sample C of the organic light emitting diode device, respectively. Further, basic information of each layer material of sample a, sample B, and sample C is collated in the following table (1).

Watch (1)

With continued reference to fig. 3, a graph of voltage versus luminance data is shown. From the data of fig. 3, it can be found that the organic light emitting diode 1' of the sample a shows relatively optimal light emitting efficiency. On the other hand, the organic light emitting diode 1' of sample C showed relatively worst light emitting efficiency. It is to be noted that the LUMO and HOMO levels of the light-emitting layer 14 'and the electron transport layer 13' of the organic light-emitting diode 1 'of sample B are consistent with the teaching of U.S. patent publication No. US2009/0208776a1, and the LUMO and HOMO levels of the light-emitting layer 14' and the hole transport layer 15 'of the organic light-emitting diode 1' of sample B are also consistent with the reasoning of those skilled in the art. On the other hand, as can be seen from the energy level structure diagram of fig. 2B, although the LUMO level and HOMO level characteristics of the light-emitting layer 14 'and the electron transport layer 13' of sample a are consistent with the teaching of U.S. patent publication No. US2009/0208776a1, the LUMO level and HOMO level characteristics of the light-emitting layer 14 'and the hole transport layer 15' of sample a are not consistent with the presumption of those skilled in the art.

As can be understood from the above description, even if engineers design and complete the fabrication of the organic light emitting diode according to the teaching of the prior art document, the obtained organic light emitting diode does not necessarily exhibit the best light emitting efficiency. Therefore, it is the most important research subject to further improve the light emitting efficiency of the organic light emitting diode by using the existing basic design knowledge and process materials. In view of the above, the inventors of the present invention have made intensive studies and finally have developed a high efficiency organic light emitting diode device according to the present invention.

Disclosure of Invention

The invention mainly aims to provide a high-efficiency organic light-emitting diode. By utilizing the existing basic design knowledge and process materials, the inventor develops and proposes the high-efficiency organic light-emitting diode, and the basic components of the high-efficiency organic light-emitting diode comprise: an anode substrate, a hole transport layer, a first light emitting layer, an electron transport layer, and a cathode layer. In the high-efficiency organic light-emitting diode, the LUMO energy levels of the hole transport layer, the first light-emitting layer and the electron transport layer form a step energy level; meanwhile, the HOMO energy levels of the hole transport layer, the first light emitting layer and the electron transport layer form a step energy level. In addition, the electron mobility of the electron transport layer of the high-efficiency organic light-emitting diode is at least two orders of magnitude higher than that of the first light-emitting layer. It should be noted that, as proved by a plurality of experimental data, the organic light emitting diode satisfying the above three conditions can certainly exhibit excellent photoelectric efficiency, which is a high efficiency organic light emitting diode device defined in the present invention.

To achieve the above objective, the present inventors provide an embodiment of the high efficiency organic light emitting diode device, which includes:

an anode substrate;

a hole transport layer formed on the anode substrate;

a first light-emitting layer formed on the hole transport layer;

an electron transport layer formed on the first light emitting layer; and

a cathode layer formed on the electron transport layer;

wherein the hole transport layer, the first light emitting layer and the electron transport layer satisfy the following conditions:

(1) the LUMO level of the first light emitting layer is lower than the LUMO level of the hole transport layer, and the HOMO level of the first light emitting layer is deeper than the HOMO level of the hole transport layer;

(2) the LUMO energy level of the electron transport layer is lower than that of the first light emitting layer, and the HOMO energy level of the electron transport layer is deeper than that of the first light emitting layer; and

(3) the electron mobility of the electron transport layer is higher than that of the first light emitting layer.

In an embodiment of the aforementioned high efficiency organic light emitting diode device of the present invention, the method further includes: a hole injection layer formed between the anode substrate and the hole transport layer; and an electron injection layer formed between the electron transport layer and the cathode layer.

In an embodiment of the aforementioned high efficiency organic light emitting diode device of the present invention, the method further includes: at least one guest dye doped in the first light-emitting layer.

In an embodiment of the aforementioned high efficiency organic light emitting diode device of the present invention, the method further includes: at least one second light-emitting layer connected with the first light-emitting layer; the second light-emitting layer is located between the first light-emitting layer and the electron transport layer, or between the first light-emitting layer and the hole transport layer.

In an embodiment of the aforementioned high efficiency organic light emitting diode device of the present invention, the method further includes: a carrier balance layer formed between the first light emitting layer and the second light emitting layer.

Drawings

FIG. 1 is a diagram illustrating a conventional energy level structure of an OLED;

FIG. 2A is a diagram showing an energy level structure of a sample A of an organic light emitting diode device;

FIG. 2B is a diagram showing an energy level structure of a sample B of an organic light emitting diode device;

fig. 2C is a diagram showing an energy level structure of a sample C of the organic light emitting diode element;

FIG. 3 is a graph of data showing voltage versus brightness;

FIG. 4 is a schematic side cross-sectional view showing a first embodiment of a high efficiency organic light emitting diode device of the present invention;

FIG. 5 is a diagram showing an energy level structure of a first embodiment of the high efficiency organic light emitting diode device of the present invention;

FIG. 6A is a graph of data showing electron mobility versus electron-hole recombination rate;

FIG. 6B is a graph of data showing electron mobility versus electron-hole recombination fraction;

FIG. 7A is a graph showing the energy level structure of a sample of organic light emitting diodes;

FIG. 7B is a graph showing the energy level structure of a sample of organic light emitting diodes;

FIG. 7C is a graph showing the energy level structure of a sample of organic light emitting diodes;

FIG. 7D is a graph showing the energy level structure of a sample of organic light emitting diodes;

FIG. 8A is a graph of data showing electron mobility versus electron-hole recombination rate;

FIG. 8B is a graph of data showing electron mobility versus electron-hole recombination fraction;

FIG. 9A is a graph of data showing electron mobility versus electron-hole recombination rate;

FIG. 9B is a graph of data showing electron mobility versus electron-hole recombination fraction;

FIG. 10A is a graph of data showing hole mobility versus electron-hole recombination;

FIG. 10B is a graph of data showing hole mobility versus electron-hole recombination fraction;

FIG. 11 is a schematic side cross-sectional view showing a second embodiment of a high efficiency organic light emitting diode of the present invention;

FIG. 12 is a schematic side cross-sectional view showing a third embodiment of a high efficiency organic light emitting diode of the present invention;

FIG. 13 is a schematic side cross-sectional view showing a fourth embodiment of a high efficiency organic light emitting diode of the present invention;

fig. 14 is a schematic side sectional view showing a fifth embodiment of a high efficiency organic light emitting diode of the present invention; and

fig. 15 is a diagram showing an energy level structure of a sixth embodiment of the high efficiency organic light emitting diode device of the present invention.

Wherein the reference numerals are:

1 high efficiency organic light emitting diode

11 anode substrate

12 hole transport layer

13 first luminescent layer

14 electron transport layer

15 cathode layer

12a hole injection layer

14a electron injection layer

13a guest dyes

16 second light-emitting layer

17 carrier balancing layer

18 interfacial layer

1' organic light emitting diode

11' cathode

13' electron transport layer

14' light-emitting layer

15' hole transport layer

18' anode

Detailed Description

In order to more clearly describe the high efficiency organic light emitting diode device proposed by the present invention, the following description will be made in detail with reference to the accompanying drawings.

First embodiment

Fig. 4 is a schematic side cross-sectional view illustrating a first embodiment of a high efficiency organic light emitting diode device according to the present invention. Also, fig. 5 is a diagram showing an energy level structure of a first embodiment of the high efficiency organic light emitting diode device of the present invention. As can be seen from fig. 4, the first embodiment of the high efficiency organic light emitting diode device 1 of the present invention has the simplest device structure, including: an anode substrate 11, a hole transport layer 12, a first light emitting layer 13, an electron transport layer 14, and a cathode layer 15. It must be particularly emphasized that the technical features of the present invention are that the hole transport layer 12, the first light emitting layer 13 and the electron transport layer 14 satisfy the following conditions:

(1) the LUMO level of the first light emitting layer 13 is lower than the LUMO level of the hole transport layer 12, and the HOMO level of the first light emitting layer 13 is deeper than the HOMO level of the hole transport layer 12;

(2) the LUMO level of the electron transport layer 14 is lower than the LUMO level of the first light emitting layer 13, and the HOMO level of the electron transport layer 14 is deeper than the HOMO level of the first light emitting layer 13; and

(3) the electron mobility of the electron transport layer 14 is higher than that of the first light emitting layer 13.

It should be noted that, according to the setting of the conditions (1) and (2), the LUMO energy levels of the hole transport layer 12, the first light emitting layer 13, and the electron transport layer 14 form a stepped energy level, and the HOMO energy levels of the hole transport layer 12, the first light emitting layer 13, and the electron transport layer 14 also form a stepped energy level. In short, no matter which organic material is selected to form the organic light emitting diode device, the organic light emitting diode device can exhibit excellent photoelectric efficiency as long as the hole transport layer 12, the first light emitting layer 13 and the electron transport layer 14 of the organic light emitting diode device satisfy the above three conditions, and is the high efficiency organic light emitting diode device 1 defined in the present invention. It should be noted that the present invention is not limited to the process materials of the anode substrate 11, the hole transport layer 12, the first light emitting layer 13, the electron transport layer 14, and the cathode layer 15; even so, the process materials of the organic light emitting diode device are commonly used for reference. Generally, the anode substrate 11 is a transparent conductive substrate, such as: an Indium Tin Oxide (ITO) transparent conductive substrate, an Indium Zinc Oxide (IZO) transparent conductive substrate, a nano silver wire transparent conductive substrate, or a graphene oxide/nano silver wire transparent conductive substrate.

On the other hand, the process materials of the hole transport layer 12, the electron transport layer 14, and the first light emitting layer 13 are set in the following tables (2), (3), and (4), respectively.

Watch (2)

Watch (3)

Watch (4)

For example, a high efficiency organic light emitting diode element 1 having a band-gap structure shown in fig. 5 has an ITO transparent conductive substrate (i.e., an anode substrate 11), a hole transport layer 12 made of TAPC, a first light emitting layer 13 made of TCTA, the first light emitting layer 13 made of TPBi, and a cathode layer 15 made of LiF/Al composite.

First verification experiment

To prove the fact that the hole transport layer, the first light emitting layer and the electron transport layer of the fabricated organic light emitting diode device can be the high efficiency organic light emitting diode device 1 defined in the present invention if they satisfy the above three conditions, the inventors completed multiple sets of experimental data by using simulation software. In the first verification experiment, we changed the electron mobility of the electron transport layer 14 and then observed the change in the Recombination rate (Recombination rate) and Recombination fraction (Recombination fraction) of electrons and holes in the first light emitting layer 13. Here, the Recombination fraction is also referred to as Recombination frequency (Recombination frequency). Fig. 6A is a data graph showing electron mobility versus recombination rate of electrons-holes, and fig. 6B is a data graph showing electron mobility versus recombination fraction of electrons-holes. In addition,

samples

1, 2, 3, and 4 in fig. 6A and 6B are organic light emitting diodes having different configurations, and the basic information of the 4 sets of samples is summarized in tables (5) and (6) below.

Watch (5)

Watch (6)

Based on the experimental data presented in fig. 6A and 6B and the energy level structures of the samples of the organic light emitting diode shown in fig. 7A, 7B, 7C, and 7D, it can be found that when the hole transport layer 12, the first light emitting layer 13, and the electron transport layer 14 of the organic light emitting diode satisfy the aforementioned condition (1) and/or condition (2), the Recombination fraction (Recombination fraction) of electrons and holes in the first light emitting layer 13 is greater than 0.6. Further, when the hole transport layer 12, the first light emitting layer 13, and the electron transport layer 14 satisfy the aforementioned conditions (1) and (2) at the same time, the recombination fraction of electrons and holes in the first light emitting layer 13 of the organic light emitting diode is greater than 0.9. Meanwhile, it can be found that when the hole transport layer 12, the first light emitting layer 13 and the electron transport layer 14 satisfy the above conditions (1) and (2) at the same time, the Recombination rate (Recombination rate) of electrons and holes in the first light emitting layer 13 increases with the increase of the electron mobility of the electron transport layer 14 under the condition of fixing the electron mobility of the hole transport layer 12 and the first light emitting layer 13. It is noted that when the electron mobility of the electron transport layer 14 is raised to be more than two orders of magnitude higher than that of the first light emitting layer 13, the recombination rate of the electrons and the holes in the first light emitting layer 13 is increased by at least 6 times.

Second verification experiment

To prove that "when the hole transport layer 12, the first light emitting layer 13, and the electron transport layer 14 satisfy the aforementioned conditions (1) and (2) at the same time, in the case of fixing the electron mobility of the hole transport layer 12 and the first light emitting layer 13, the recombination rate of electrons and holes in the first light emitting layer 13 increases as the electron mobility of the electron transport layer 14 increases. The inventor utilizes simulation software to complete multiple sets of experimental data. In the second verification experiment, the electron mobility of the first light-emitting layer 13 was changed and then the change in the recombination rate and the recombination fraction of electrons and holes in the first light-emitting layer 13 was observed. Here, the Recombination fraction (Recombination frequency) is also referred to as a Recombination frequency (Recombination frequency). Fig. 8A is a data graph showing electron mobility versus recombination rate of electrons-holes, and fig. 8B is a data graph showing electron mobility versus recombination fraction of electrons-holes. In addition,

samples

1, 2, 3, and 4 in fig. 8A and 8B are organic light emitting diodes having different configurations, and the basic information of the 4 sets of samples is summarized in the above tables (5) and (6).

From the experimental data of sample 2, it can be found that when the hole transport layer 12, the first light emitting layer 13 and the electron transport layer 14 satisfy the aforementioned conditions (1) and (2) at the same time, the recombination rate of electrons and holes in the first light emitting layer 13 does not increase with the increase of the electron mobility of the first light emitting layer 13 under the condition of fixing the electron mobility of the hole transport layer 12 and the electron transport layer 14. In contrast, from the experimental data of

samples

3 and 4, it can be found that when the hole transport layer 12, the first light emitting layer 13, and the electron transport layer 14 only satisfy the aforementioned condition (1), in the case of fixing the electron mobility of the hole transport layer 12 and the electron transport layer 14, the recombination frequency and the recombination rate of electrons and holes in the first light emitting layer 13 decrease with the increase of the electron mobility of the first light emitting layer 13, and the recombination frequency and the recombination rate stop decreasing until the electron mobility of the first light emitting layer 13 is increased to more than two orders of magnitude greater than the electron mobility of the electron transport layer 14.

On the other hand, fig. 9A is a data graph showing electron mobility versus recombination rate of electrons-holes, and fig. 9B is a data graph showing electron mobility versus recombination fraction of electrons-holes. Based on the experimental data presented in fig. 9A and 9B, it can be seen that, in the case of fixing the electron mobility of the first light emitting layer 13 and the electron transport layer 14, the recombination rate of electrons and holes in the first light emitting layer 13 does not change with the increase of the electron mobility of the hole transport layer 12. Further, fig. 10A is a data graph showing hole mobility versus recombination rate of electrons-holes, and fig. 10B is a data graph showing hole mobility versus recombination fraction of electrons-holes. According to the experimental data presented in fig. 10A and 10B, it can be found that, under the condition of fixing the electron mobility of the first light emitting layer 13 and the electron transport layer 14, the recombination rate of the electrons and the holes in the first light emitting layer 13 does not have any variation along with the increase of the hole mobility of the hole transport layer 12.

Therefore, the experimental results confirm that the key factor affecting the recombination frequency and recombination rate of electrons and holes in the first light-emitting layer 13 is the electron mobility ratio between the electron transport layer 14 and the first light-emitting layer 13; preferably, the electron mobility ratio between the electron transport layer 14 and the first light-emitting layer 13 amounts to 10²At this time, the electrons and holes exhibit excellent recombination frequency and recombination rate in the first light emitting layer 13. On the other hand, when the hole transport layer 12 of the organic light emitting diode, the firstWhen the light-emitting layer 13 and the electron transport layer 14 satisfy both of the above conditions (1) and (2), the recombination fraction of electrons and holes in the first light-emitting layer 13 is greater than 0.9.

Second embodiment

It should be repeatedly emphasized that the present invention is not particularly limited to the material of the organic light emitting diode. No matter which organic materials are selected to be used to form the organic light emitting diode device, as long as the hole transport layer 12, the first light emitting layer 13 and the electron transport layer 14 of the organic light emitting diode device satisfy the above three conditions, the organic light emitting diode device can exhibit excellent photoelectric efficiency, and is the high efficiency organic light emitting diode device 1 defined in the present invention. Meanwhile, the present invention is not particularly limited to the structure of the organic light emitting diode, as long as the manufactured organic light emitting diode includes the basic structure of the anode substrate 11, the hole transport layer 12, the first light emitting layer 13, the electron transport layer 14, the cathode layer 15, and the like.

For the above reasons, the present invention also provides a second embodiment of the organic light emitting diode device 1 with high efficiency. Fig. 11 is a schematic side sectional view showing a second embodiment of the high efficiency organic light emitting diode of the present invention. As can be seen from comparing fig. 4 and fig. 11, a second embodiment of the high efficiency organic light emitting diode device 1 of the present invention can be obtained by adding a Hole Injection Layer (HIL) 12a and an Electron Injection Layer (EIL) 14a to the first embodiment. As shown in fig. 11, the hole injection layer 12a is formed between the anode substrate 11 and the hole transport layer 12, and the electron injection layer 14a is formed between the electron transport layer 14 and the cathode layer 15. Further, the process materials for the hole injection layer 12a and the electron injection layer 14a are listed in the following tables (7) and (8), respectively.

Watch (7)

Watch (8)

Third and fourth embodiments

Furthermore, the present invention also provides a third embodiment of a high efficiency organic light emitting diode element 1. Fig. 12 is a schematic side sectional view showing a third embodiment of the high efficiency organic light emitting diode according to the present invention. Comparing fig. 4 and fig. 12, it can be known that the second embodiment of the high efficiency organic light emitting diode 1 of the present invention can be obtained by adding at least one guest dye 13a into the first embodiment. As shown in fig. 12, the at least one guest dye 13a is doped in the first light emitting layer 13. Further, the present invention provides yet another fourth embodiment of the high efficiency organic light emitting diode element 1. Fig. 13 is a schematic side sectional view showing a fourth embodiment of the high efficiency organic light emitting diode according to the present invention. Comparing fig. 12 and fig. 13, it can be seen that the fourth embodiment of the high efficiency organic light emitting diode device 1 of the present invention can be obtained by adding a second light emitting layer 16 to the third embodiment. As shown in fig. 13, the second light-emitting layer 16 is connected to the first light-emitting layer 13 and located between the first light-emitting layer 13 and the electron transport layer 14. Of course, the second light-emitting layer 16 may be located between the first light-emitting layer 13 and the hole-transporting layer 12. It should be noted that the second light-emitting layer 16 may also be doped with at least one guest dye 13 a.

Fifth embodiment

The present invention further provides a fifth embodiment of the high efficiency organic light emitting diode device 1. Fig. 14 is a schematic side sectional view showing a fifth embodiment of the high efficiency organic light emitting diode according to the present invention. Comparing fig. 13 and fig. 14, it can be seen that the fifth embodiment of the high efficiency organic light emitting diode device 1 of the present invention can be obtained by adding a carrier balancing layer 17 to the fourth embodiment. As shown in fig. 14, a carrier balance layer 17 is formed between the first light emitting layer 13 and the second light emitting layer 16; the carrier balance layer 17 may be a mixed layer of the first light emitting layer 13 and the second light emitting layer 16. More precisely, the carrier balance layer 17 is formed by mixing part of the first light emitting layer 13 and part of the second light emitting layer 16. On the other hand, the carrier balancing layer 17 may also be a hole balancing layer, an electron balancing layer, or a combination of any two of the above. Exemplary process materials for the hole balance layer and the electron balance layer are listed in tables (9) and (10), respectively.

Watch (9)

Watch (10)

Finally, the present invention provides yet another sixth embodiment of the high efficiency organic light emitting diode device 1. Fig. 15 is a diagram showing an energy level structure of a sixth embodiment of the high efficiency organic light emitting diode device of the present invention. Comparing fig. 5 and fig. 15, it can be seen that the sixth embodiment of the high efficiency organic light emitting diode device 1 of the present invention can be obtained by adding an interface layer 18 to the first embodiment. As shown in fig. 15, the interfacial layer 18 is formed between the electron transport layer 14 and the cathode layer 15, so as to achieve the effect of increasing the voltage across the electron transport layer 14 when the voltage is applied to the high efficiency organic light emitting diode device 1. Also, exemplary process materials for the interfacial layer 18 are listed in table (11) below.

Watch (11)

Thus, the above-mentioned description has fully and clearly illustrated the high efficiency organic light emitting diode device disclosed in the present invention; moreover, we can see that the invention has the following advantages:

(1) the present invention develops and proposes a high efficiency organic light emitting diode device 1 using the existing basic design knowledge and process materials, and the basic constitution thereof comprises: an anode substrate 11, a hole transport layer 12, a first light emitting layer 13, an electron transport layer 14, and a cathode layer 15. In the high efficiency organic light emitting diode device 1, the LUMO energy levels of the hole transport layer 12, the first light emitting layer 13 and the electron transport layer 14 form a step energy level; meanwhile, the HOMO levels of the hole transport layer 12, the first light emitting layer 13 and the electron transport layer 14 also form a stepped level. In addition, the electron mobility of the electron transport layer 14 of the high efficiency organic light emitting diode element 1 is at least two orders of magnitude higher than the electron mobility of the first light emitting layer 13. It should be noted that, as proved by a plurality of experimental data, the organic light emitting diode satisfying the above three conditions can certainly exhibit excellent photoelectric efficiency, which is a high efficiency organic light emitting diode device defined in the present invention.

It should be emphasized that the above detailed description is specific to possible embodiments of the invention, but this is not to be taken as limiting the scope of the invention, and all equivalent implementations or modifications that do not depart from the technical spirit of the invention are intended to be included within the scope of the present invention.

Claims

1. A high efficiency organic light emitting diode device, comprising:

an anode substrate;

a hole transport layer formed on the anode substrate;

a first light-emitting layer formed on the hole transport layer;

an electron transport layer formed on the first light emitting layer; and

a cathode layer formed on the electron transport layer;

(3) the electron mobility of the electron transport layer is higher than that of the first light emitting layer;

wherein, when the hole transport layer, the first light emitting layer, and the electron transport layer satisfy the condition (1) and the condition (2) at the same time, a Recombination rate (Recombination fraction) of electrons and holes in the first light emitting layer increases with an increase in electron mobility of the electron transport layer while fixing the electron mobility of the hole transport layer and the first light emitting layer, and the Recombination fraction (Recombination fraction) of electrons and holes in the first light emitting layer is greater than 0.6;

when the electron mobility of the electron transport layer is raised to be more than two orders of magnitude higher than that of the first light emitting layer, the recombination rate of electrons and holes in the first light emitting layer is increased by at least 6 times.

2. A high efficiency organic light emitting diode device as claimed in claim 1, further comprising:

a hole injection layer formed between the anode substrate and the hole transport layer; and

an electron injection layer formed between the electron transport layer and the cathode layer.

3. A high efficiency organic light emitting diode device as claimed in claim 1, further comprising:

at least one guest dye doped in the first light-emitting layer.

4. A high efficiency organic light emitting diode device as claimed in claim 1, further comprising:

at least one second light-emitting layer connected with the first light-emitting layer; the second light-emitting layer is located between the first light-emitting layer and the electron transport layer, or between the first light-emitting layer and the hole transport layer.

5. A high efficiency organic light emitting diode device as claimed in claim 1, further comprising:

an interface layer formed between the electron transport layer and the cathode layer for increasing the voltage across the electron transport layer when the high efficiency OLED device is applied with a voltage.

6. The high efficiency OLED device as recited in claim 1, wherein the anode substrate is a transparent conductive substrate.

7. The high efficiency organic light emitting diode device of claim 4, further comprising:

a carrier balance layer formed between the first light emitting layer and the second light emitting layer.

8. The OLED device as claimed in claim 5, wherein the process material of the interfacial layer is any one of the following: b3PyPB, TmPyPB or BCP.

9. The device as claimed in claim 7, wherein the carrier balancing layer is made of a hole balancing material and/or an electron balancing material.

10. The high efficiency OLED device as claimed in claim 9, wherein the hole-balancing material is any one of the following: MeO-TPD, F4TCNQ (P3HT): F4TCNQ, or (m-MTDATA): F4 TCNQ; also, the electron-balancing material may be any one of: (BPhen): Cs, Cs₂CO₃BPhen, or (TPBi) Cs₂CO₃。

11. A high efficiency oled cell as claimed in claim 9A member, wherein the electron-balancing material may be any one of: (BPhen): Cs, Cs₂CO₃BPhen, or (TPBi) Cs₂CO₃。