An organic light-emitting diode

Abstract

The present invention discloses an organic light-emitting diode (OLED), comprising a transparent substrate, an anode, a first organic acceptor layer, a first organic heterojunction, a first organic donor layer, an electron blocking layer, a light-emitting layer, an electron transport layer, a LiF / Al layer, a second organic acceptor layer, a second organic heterojunction, a second organic donor layer, and a cathode, stacked in order from bottom to top. The first organic acceptor layer, the first organic heterojunction, and the first organic donor layer constitute a hole injection layer; the second organic acceptor layer, the second organic heterojunction, and the second organic donor layer constitute an electron injection layer. The present invention has higher charge generation efficiency, overcomes the device's dependence on the electrode work function, and improves device stability.

Description

Technical Field

[0001] The present invention relates to the technical field of organic electroluminescence, and in particular to an organic light emitting diode. Background Art

[0002] In 1987, Dr. Qingyun Deng and others from Eastman Kodak (Organic electroluminescent diodes, CW Tang and S.A. Van Slyke, Appl. Phys. Lett., 1987, 51913-915.) invented high-efficiency organic light-emitting diodes (OLEDs), which set off a worldwide research boom in OLED materials and devices. In the past three decades, OLEDs have developed rapidly, and corresponding commercial products have been applied to display and lighting. However, there are still many unresolved problems in this field that hinder the further commercialization of OLEDs. In lighting applications, a higher brightness is usually required, such as 1000 cd / m 2 However, high brightness can lead to significant degradation in device efficiency and lifetime. OLEDs typically consist of a sandwich structure consisting of a hole-transport layer, an electron-transport layer, and an intermediate light-emitting layer. These thin layers, typically around 100-200 nm, are prone to problems such as defective pixels and leakage current. Therefore, in practical applications, particularly in the lighting sector, stacked device structures are almost exclusively used. The concept of stacking was first proposed by Professor Kido of Japan, and consists of multiple OLED units connected in series via a connecting layer. Stacked devices can achieve high brightness with low currents, significantly improving device stability. Furthermore, their flexible and versatile device structure can meet diverse design requirements, while their relatively large device thickness prevents problems such as defective pixels and leakage current. Stacked OLEDs not only further improve device efficiency but also exponentially increase device lifetime, making them highly sought after. However, the development of an efficient charge generation layer (CGL), the core of stacked OLED devices, and the investigation of their operating mechanism have become both hot topics and challenges in research.

[0003] Semiconductor heterojunctions, as the foundation for semiconductor optoelectronic devices, have been extensively studied both theoretically and experimentally. Traditional inorganic semiconductor-based pn heterojunctions are typically depleted, and their current-voltage characteristics can be well simulated using drift-diffusion models. Recently, organic semiconductors have been used to realize accumulation-type heterojunctions, which accumulate holes on the p-type side of the space charge region and electrons on the n-type side. Drawing on the concept of a blended active layer in organic solar cells, this blended bulk heterojunction has been introduced as a connecting layer in stacked devices, achieving efficient charge generation. Using this organic semiconductor bulk heterojunction as a charge connecting layer in organic light-emitting diodes (OLEDs) has been shown to significantly enhance electron and hole injection, significantly improving device efficiency while remaining independent of the work function of the electrode metal. This improvement is attributed to the efficient generation of free charge carriers due to the large-area accumulation-type contact within the organic semiconductor bulk heterojunction. Therefore, studying the charge generation and injection mechanisms of organic semiconductor bulk heterojunctions is of great significance and plays a crucial role in further improving the performance of OLEDs.

[0004] It has been reported that triplet excitons in organic semiconductors have a certain probability of being annihilated by polarons, forming a polaron-excited state (triplet polaron annihilation, TPQ). In the organic electroluminescence process, triplet excitons account for the vast majority of the total exciton population. Polaron-exciton collisions affect the exciton lifetime and can also create new energy levels in the band gap. Because polaron-exciton excited states can return to the ground state through radiative transitions, collisions can have a significant impact on the device's electroluminescence external quantum efficiency. Therefore, addressing the TPQ issue in OLEDs is urgent. Summary of the Invention

[0005] In order to overcome the above-mentioned shortcomings and deficiencies of the prior art, the object of the present invention is to provide an organic light-emitting diode that uses an organic semiconductor heterojunction with a large-area accumulation-type contact as the electron injection layer and the hole injection layer to obtain high-efficiency OLEDs.

[0006] The purpose of the present invention is achieved through the following technical solutions:

[0007] An organic light-emitting diode comprises a transparent substrate, an anode, a first organic acceptor layer, a first organic heterojunction, a first organic donor layer, an electron blocking layer, a light-emitting layer, an electron transport layer, a LiF / Al layer, a second organic acceptor layer, a second organic heterojunction, a second organic donor layer and a cathode, which are stacked in sequence from bottom to top;

[0008] The first organic acceptor layer, the first organic heterojunction, and the first organic donor layer constitute a hole injection layer;

[0009] The second organic acceptor layer, the second organic heterojunction, and the second organic donor layer constitute an electron injection layer;

[0010] The first organic receptor layer and the second organic receptor layer are both made of organic receptor materials;

[0011] The first organic donor layer and the second organic donor layer are both made of organic donor materials;

[0012] The first organic heterojunction and the second organic body heterojunction are both prepared by mixing an organic acceptor material and an organic donor material in a mass ratio of 1: (0.8-1.2);

[0013] The organic donor material is one of the following donor materials:

[0014]

[0015] The organic acceptor material is

[0016]

[0017] Preferably, the thickness of the first organic acceptor layer is 12 to 18 nanometers; the thickness of the first organic heterojunction is 18 to 22 nanometers; and the thickness of the first organic donor layer is 38 to 42 nanometers.

[0018] Preferably, the thickness of the second organic acceptor layer is 3 to 7 nanometers; the thickness of the second organic heterojunction is 3 to 7 nanometers; the 3 to 7 nanometers.

[0019] Preferably, the LiF / Al layer consists of a LiF layer with a thickness of 1 to 2 nanometers and an Al layer with a thickness of 0.4 to 0.6 nanometers.

[0020] Preferably, the material of the electron transport layer is PO-T2T, and the thickness is 32 to 38 nanometers.

[0021] Preferably, the light-emitting layer is a blue light-emitting layer, a green light-emitting layer or a red light-emitting layer; and has a thickness of 18 to 22 nanometers.

[0022] Preferably, the blue light emitting layer uses blue light Firpic as the guest material and uses mCBP / PO-T2T exciplex as the host material.

[0023] Preferably, the green light emitting layer uses green light Ir(ppy)2acaca as the guest material and TCTA as the single host light emitting carrier.

[0024] Preferably, the red light emitting layer uses red MDQ as the guest material and TCTA as the single host light emitting carrier.

[0025] Preferably, the material of the electron blocking layer is TCTA, and the thickness is 3 to 7 nanometers.

[0026] The principle of the present invention is:

[0027] The electron injection layer and hole injection layer of the present invention adopt an organic semiconductor bulk heterojunction with a large-area accumulation-type contact, and the organic semiconductor heterojunction is composed of an organic semiconductor donor material and an organic semiconductor acceptor material. The essential requirement for constructing an organic bulk heterojunction with a large-area accumulation-type interface is the matching of the energy level structure of the organic molecules used, that is, the HOMO of the organic semiconductor donor material must be energetically located near the LUMO of the organic acceptor material molecule, and the Fermi level of the organic donor material is higher than the Fermi level of the organic acceptor material. When they come into contact, charge transfer occurs from the organic donor molecule to the organic acceptor molecule, resulting in hole accumulation on the donor side and electron accumulation on the acceptor side in the space charge region. The organic semiconductor heterojunction of the present invention is formed by blending the organic semiconductor donor material and the organic semiconductor acceptor material. Compared with the traditional planar heterojunction, the bulk heterojunction has a larger contact surface, which can greatly improve the charge transfer at the donor-acceptor interface, resulting in higher charge generation efficiency.

[0028] Compared with the prior art, the present invention has the following advantages and beneficial effects:

[0029] The present invention utilizes the large-area accumulation type donor-acceptor receiving area of ​​the organic semiconductor heterojunction to produce efficient charge generation characteristics. Under an external electric field, the electrons (holes) generated can be efficiently injected into the light-emitting unit for compound luminescence, and the remaining holes (electrons) are compounded at the interface between the heterojunction and the cathode (anode) to maintain electrical neutrality. Compared to traditional planar heterojunctions, hybrid heterojunctions have a larger donor-acceptor contact area and produce higher charge transfer characteristics. Since electrons are not injected directly from the cathode, but are derived from the efficiently generated charges at the heterojunction interface, this method can effectively avoid the dependence of the traditional electron injection layer on the cathode work function. On the other hand, compared to traditional electron injection layers, this method can improve the injection balance of electrons and holes, thereby improving the efficiency of the device. BRIEF DESCRIPTION OF THE DRAWINGS

[0030] Figure 1 FIG. 4 is a device structure diagram of an organic light emitting diode according to an embodiment of the present invention.

[0031] Figure 2 The external quantum efficiency (EQE)-brightness (B) characteristic curve, current efficiency (CE)-brightness characteristic curve, power efficiency (PE)-brightness characteristic curve, voltage-current density characteristic curve and brightness-current density characteristic curve, and the electroluminescence normalized spectrum diagram of the device B1 of an embodiment of the present invention are shown.

[0032] Figure 3The external quantum efficiency (EQE)-brightness (B) characteristic curve, current efficiency (CE)-brightness characteristic curve, power efficiency (PE)-brightness characteristic curve, voltage-current density characteristic curve and brightness-current density characteristic curve, and the electroluminescence normalized spectrum diagram of the device G1 of an embodiment of the present invention are shown.

[0033] Figure 4 The external quantum efficiency (EQE)-brightness (B) characteristic curve, current efficiency (CE)-brightness characteristic curve, power efficiency (PE)-brightness characteristic curve, voltage-current density characteristic curve and brightness-current density characteristic curve, and the electroluminescence normalized spectrum diagram of the device R1 of an embodiment of the present invention are shown. DETAILED DESCRIPTION

[0034] The present invention will be further described in detail below with reference to the examples, but the embodiments of the present invention are not limited thereto.

[0035] Example 1

[0036] The organic light emitting diode of this embodiment is as follows Figure 1 As shown, it includes a transparent substrate, an anode, a first organic acceptor layer, a first organic heterojunction, a first organic donor layer, an electron blocking layer, a light-emitting layer, an electron transport layer, a LiF / Al thin layer, a second organic acceptor layer, a second organic heterojunction, a second organic donor layer and a cathode stacked in sequence from bottom to top;

[0037] In this embodiment, the first organic acceptor layer, the first organic heterojunction, and the first organic donor layer constitute a hole injection layer;

[0038] In this embodiment, the second organic acceptor layer, the second organic heterojunction, and the second organic donor layer constitute an electron injection layer;

[0039] In this embodiment, the first organic receptor layer and the second organic receptor layer are both made of organic receptor materials;

[0040] In this embodiment, the first organic donor layer and the second organic donor layer are both made of organic donor materials;

[0041] In this embodiment, the first organic heterojunction and the second organic heterojunction are both prepared by mixing an organic acceptor material and an organic donor material;

[0042] The organic donor material of this embodiment is 4,4'-cyclohexylbis(N,N-bis(4-methylphenyl)aniline) (TAPC), which has the following structural formula:

[0043]

[0044] The organic acceptor material of this embodiment is dipyrazino(2,3-f:2',3'-h)quinoxaline-2,3,6,7,10,11-hexanitrile (HAT-CN), which has the following structure:

[0045]

[0046] The preparation method of the blue organic light-emitting diode of this embodiment includes the following steps: the device uses 30 mm × 30 mm transparent glass as a substrate, and patterned indium tin oxide is attached to the front with a thickness of 170 nanometers and a square resistance of 10 ohms / square meter. Before preparing the device, the ITO substrate is ultrasonically treated for 1 hour and 30 minutes, washed 3 times with ITO washing solution, and the impurities on the ITO surface are rinsed with a large amount of deionized water, blown dry with nitrogen, and then placed in an oven at a temperature of 120 degrees Celsius for 1 hour to keep the surface dry. Before vacuum deposition, the ITO surface is treated with UV ozone for 4 minutes. This process not only cleans the ITO surface, but also reduces the work function of ITO. The organic material and the metal cathode are vacuum evaporated and deposited according to the drug regulations. The air pressure in the transfer chamber is evacuated to below 5 Pa, and the manipulator is operated to transfer the pretreated ITO substrate to the evaporation chamber. All functional layers are in a high vacuum environment (5×10 5The deposition process was carried out in a medium of 100 Pa (Pa). During the deposition process, the rotation speed of the evaporation substrate was controlled at 10 r / min to ensure the formation of a dense and uniform thin film. Organic materials were deposited by heating an organic evaporation source, while metal materials and non-electrode materials were deposited by a metal evaporation source. The first organic acceptor layer, the first organic semiconductor heterojunction, the first organic donor layer, the electron blocking layer, the light-emitting layer, the electron transport layer, the LiF layer, the thin Al layer, the second organic acceptor layer, the second organic semiconductor heterojunction, the second organic donor layer, and the cathode Al layer were sequentially deposited. During all deposition processes, the evaporation rate was monitored in real time using a Protek universal counter U2000A frequency counter, and the rate was controlled to 0.1 nm / s by adjusting the evaporation source. The resulting device had an effective area of ​​0.08 square centimeters, representing the overlapping area of ​​Al and ITO. The blue light OLED device based on HAT-CN / HAT-CN:TAPC (1:1) / TAPC as the hole and electron injection layer is device B1, and the structure is ITO / HAT-CN (15 nm) / HAT-CN:TAPC (1:1, 20 nm) / TAPC (40 nm) / TCTA (5 nm) / mCBP (5 nm) / mCBP:PO-T2T:Firpic (1:1:15%, 20 nm) / PO-T2T (35 nm) / LiF (1.5 nm) / Al (0.5 nm) / HAT-CN (5 nm) / HAT-CN:TAPC (1:1, 5 nm) / TAPC (5 nm) / Al (100 nm). The hole injection layer (HAT-CN (15 nm) / HAT-CN:TAPC (1:1, 20 nm) / TAPC (40 nm) is used, while TCTA (5 nm) serves as an electron blocking layer. mCBP (5 nm) is used to expand the exciton recombination zone. mCBP:PO-T2T:Firpic (1:1:15%, 20 nm) serves as the light-emitting layer. PO-T2T (35 nm) serves as the electron transport layer. Al (100 nm) serves as the cathode. The electron injection layer comprises a three-layer structure consisting of HAT-CN (5 nm) / HAT-CN:TAPC (1:1, 5 nm) / TAPC (5 nm), encompassing a bulk heterojunction. LiF (1.5 nm) / Al (0.5 nm) is used to reduce the electron injection barrier.

[0047] Figure 2 (a) is the external quantum efficiency (EQE)-brightness (B) characteristic curve and current efficiency (CE)-brightness characteristic curve of device B1. Figure 2 Middle (b) is the power efficiency (PE)-luminance characteristic curve of device B1. Figure 2 Middle (c) is the voltage-current density characteristic curve and brightness-current density characteristic curve of device B1. Figure 2(d) shows the normalized electroluminescence spectrum of device B1. Device B1 has a minimum turn-on voltage of 2.6 volts, a maximum EQE of 25.8%, a maximum current efficiency of 46.8 candt / ampere, and a maximum power efficiency of 50 lumens / watt.

[0048] Example 2

[0049] The green organic light emitting diode of this embodiment uses an organic semiconductor heterojunction HAT-CN / HAT-CN:TAPC (1:1) / TAPC as an electron injection layer. Its preparation method includes the following steps: the device uses a 30 mm × 30 mm transparent glass as a substrate, and a patterned indium tin oxide with a thickness of 170 nm and a sheet resistance of 10 ohms / square meter is attached to the front. Before preparing the device, the ITO substrate is ultrasonically treated for 1 hour and 30 minutes, washed 3 times with ITO cleaning solution, and the impurities on the ITO surface are rinsed with a large amount of deionized water. It is blown dry with nitrogen and then placed in an oven at a temperature of 120 degrees Celsius for 1 hour to keep the surface dry. Before vacuum deposition, the ITO surface is treated with UV ozone for 4 minutes. This process not only cleans the ITO surface, but also reduces the work function of ITO. The organic material and the metal cathode are vacuum evaporated and deposited according to the drug regulations. The air pressure of the transfer chamber is pumped down to below 5 Pa, and the manipulator is operated to transfer the pretreated ITO substrate to the evaporation chamber. All functional layers are placed in a high vacuum environment (5×10 5The deposition process was carried out in a medium of 100 Pa (Pa). During the deposition process, the substrate rotation speed was controlled at 10 r / min to ensure the formation of a dense and uniform thin film. Organic materials were deposited by heating an organic evaporation source, while metal materials and non-electrode materials were deposited by a metal evaporation source. Subsequently, an organic acceptor layer, an organic semiconductor heterojunction, an organic donor layer, an electron blocking layer, a light-emitting layer, an electron transport layer, a LiF layer, a thin Al layer, an organic acceptor layer, an organic semiconductor heterojunction, an organic donor layer, and finally a cathode Al layer were deposited. During all deposition processes, the evaporation rate was monitored in real time using a Protek universal counter U2000A frequency counter, and the rate was controlled to 0.1 nm / s by adjusting the evaporation source. The resulting device had an effective area of ​​0.08 square centimeters, representing the overlapping area of ​​Al and ITO. The green light OLED device based on HAT-CN / HAT-CN:TAPC (1:1) / TAPC as the hole and electron injection layer is device G1, and the structure is ITO / HAT-CN (15 nm) / HAT-CN:TAPC (1:1, 20 nm) / TAPC (40 nm) / TCTA (5 nm) / TCTA:Ir(ppy)2acac (1:15%, 20 nm) / PO-T2T (35 nm) / LiF (1.5 nm) / Al (0.5 nm) / HAT-CN (5 nm) / HAT-CN:TAPC (1:1, 5 nm) / TAPC (5 nm) / Al (100 nm). The hole injection layer (HAT-CN (15 nm) / HAT-CN:TAPC (1:1, 20 nm) / TAPC (40 nm) is used; TCTA (5 nm) serves as an electron blocking layer and extends the exciton recombination zone; TCTA:Ir(ppy)2acac (1:15%, 20 nm) serves as the light-emitting layer; PO-T2T (35 nm) serves as the electron transport layer; and Al (100 nm) serves as the cathode. The electron injection layer comprises a three-layer structure comprising a bulk heterojunction of HAT-CN (5 nm) / HAT-CN:TAPC (1:1, 5 nm) / TAPC (5 nm). LiF (1.5 nm) / Al (0.5 nm) is used to reduce the electron injection barrier.

[0050] Figure 3 (a) is the external quantum efficiency (EQE)-brightness (B) characteristic curve and current efficiency (CE)-brightness characteristic curve of device G1. Figure 3 Middle (b) is the power efficiency (PE)-luminance characteristic curve of device G1. Figure 3 Middle (c) is the voltage-current density characteristic curve and brightness-current density characteristic curve of device G1. Figure 3(d) shows the normalized electroluminescence spectrum of device G1. The minimum turn-on voltage of device G1 is 2.6 volts, with a maximum EQE of 13.2%, a maximum current efficiency of 44.2 candt / ampere, and a maximum power efficiency of 43.7 lumens / watt.

[0051] Example 3

[0052] The red organic light emitting diode of this embodiment uses an organic semiconductor heterojunction HAT-CN / HAT-CN:TAPC (1:1) / TAPC as an electron injection layer, and its preparation method includes the following steps: the device uses a 30 mm × 30 mm transparent glass as a substrate, and a patterned indium tin oxide with a thickness of 170 nm and a sheet resistance of 10 ohms / square meter is attached to the front. Before preparing the device, the ITO substrate is ultrasonically treated for 1 hour and 30 minutes, washed 3 times with ITO cleaning solution, and the impurities on the ITO surface are rinsed with a large amount of deionized water, blown dry with nitrogen, and then placed in an oven at a temperature of 120 degrees Celsius for 1 hour to keep the surface dry. Before vacuum deposition, the ITO surface is treated with UV ozone for 4 minutes. This process not only cleans the ITO surface, but also reduces the work function of ITO. The organic material and the metal cathode are vacuum evaporated and deposited according to the drug regulations. The air pressure of the transfer chamber is pumped down to below 5 Pa, and the manipulator is operated to transfer the pretreated ITO substrate to the evaporation chamber. All functional layers are placed in a high vacuum environment (5×10 5The deposition process was carried out in a medium of 100 Pa (Pa). During the deposition process, the substrate rotation speed was controlled at 10 r / min to ensure the formation of a dense and uniform thin film. Organic materials were deposited by heating an organic evaporation source, while metal materials and non-electrode materials were deposited by a metal evaporation source. Subsequently, an organic acceptor layer, an organic semiconductor heterojunction, an organic donor layer, an electron blocking layer, a light-emitting layer, an electron transport layer, a LiF layer, a thin Al layer, an organic acceptor layer, an organic semiconductor heterojunction, an organic donor layer, and finally a cathode Al layer were deposited. During all deposition processes, the evaporation rate was monitored in real time using a Protek universal counter U2000A frequency counter, and the rate was controlled to 0.1 nm / s by adjusting the evaporation source. The resulting device had an effective area of ​​0.08 square centimeters, representing the overlapping area of ​​Al and ITO. The red light OLED device based on HAT-CN / HAT-CN:TAPC (1:1) / TAPC as the hole and electron injection layer is device R1, and the structure is ITO / HAT-CN (15 nm) / HAT-CN:TAPC (1:1, 20 nm) / TAPC (40 nm) / TCTA (5 nm) / TCTA:MDQ (1:3%, 20 nm) / PO-T2T (35 nm) / LiF (1.5 nm) / Al (0.5 nm) / HAT-CN (5 nm) / HAT-CN:TAPC (1:1, 5 nm) / TAPC (5 nm) / Al (100 nm). The hole injection layer consists of HAT-CN (15 nm) / HAT-CN:TAPC (1:1, 20 nm) / TAPC (40 nm), TCTA (5 nm) serves as an electron blocking layer and extends the exciton recombination zone, TCTA:MDQ (1:3%, 20 nm) serves as the light-emitting layer, PO-T2T (35 nm) serves as the electron transport layer, and Al (100 nm) serves as the cathode. The electron injection layer is a three-layer structure consisting of HAT-CN (5 nm) / HAT-CN:TAPC (1:1, 5 nm) / TAPC (5 nm), containing a bulk heterojunction. LiF (1.5 nm) / Al (0.5 nm) is used to reduce the electron injection barrier.

[0053] Figure 4 (a) is the external quantum efficiency (EQE)-brightness (B) characteristic curve and current efficiency (CE)-brightness characteristic curve of device R1. Figure 4 (b) is the power efficiency (PE)-brightness characteristic curve of device R1. Figure 4 Middle (c) is the voltage-current density characteristic curve and brightness-current density characteristic curve of device R1. Figure 4 (d) shows the normalized electroluminescence spectrum of device R1. The minimum turn-on voltage of device R1 is 2.6 volts, with a maximum EQE of 8.8%, a maximum current efficiency of 19.4 candt / ampere, and a maximum power efficiency of 19.5 lumens / watt.

[0054] In the above embodiment, the organic donor material may also be N,N'-diphenyl-N,N'-(1-naphthyl)-1,1'-biphenyl-4,4'-diamine (NPB) or 3,3-bis(N-carbazole)-1,1-biphenyl; 3,3-bis(9H-carbazole-9-yl)-1,1-biphenyl (mCBP), having the following structure:

[0055]

[0056] Compared to traditional planar heterojunctions, the blended bulk heterojunction of the present invention has a larger accumulation-type organic donor-acceptor interface, which can greatly improve the charge transfer ability between the two materials and has more efficient charge generation characteristics. Under an external electric field, the electrons (holes) generated can be efficiently injected into the light-emitting unit for composite luminescence, and the remaining holes (electrons) are recombined at the interface between the heterojunction and the cathode (anode) to maintain electrical neutrality. Compared to traditional planar heterojunctions, the hybrid heterojunction of the present invention has a larger donor-acceptor contact area and produces higher charge transfer characteristics. Since electrons are not injected directly from the cathode, but come from the charges efficiently generated at the heterojunction interface, this method can effectively avoid the dependence of the traditional electron injection layer on the cathode work function. On the other hand, compared to traditional electron injection layers, this method can improve the injection balance of electrons and holes, thereby improving the efficiency and stability of the device.

[0057] The above embodiments are preferred implementation modes of the present invention, but the implementation modes of the present invention are not limited to the embodiments. Any other changes, modifications, substitutions, combinations, and simplifications that do not deviate from the spirit and principles of the present invention should be considered as equivalent replacement methods and are included in the scope of protection of the present invention.

Claims

1. An organic light emitting diode, characterized in that: The device comprises a transparent substrate, an anode, a first organic acceptor layer, a first organic heterojunction, a first organic donor layer, an electron blocking layer, a light-emitting layer, an electron transport layer, a LiF / Al layer, a second organic acceptor layer, a second organic heterojunction, a second organic donor layer and a cathode, which are sequentially stacked from bottom to top; The first organic acceptor layer, the first organic heterojunction, and the first organic donor layer constitute a hole injection layer; The second organic acceptor layer, the second organic heterojunction, and the second organic donor layer constitute an electron injection layer; The first organic receptor layer and the second organic receptor layer are both made of organic receptor materials; The first organic donor layer and the second organic donor layer are both made of organic donor materials; The first organic heterojunction and the second organic body heterojunction are both prepared by mixing an organic acceptor material and an organic donor material in a mass ratio of 1: (0.8-1.2); The organic donor material is one of the following donor materials: The organic receptor material is:

2. The organic light emitting diode according to claim 1, wherein: The thickness of the first organic acceptor layer is 12 to 18 nanometers; the thickness of the first organic heterojunction is 18 to 22 nanometers; and the thickness of the first organic donor layer is 38 to 42 nanometers.

3. The organic light emitting diode according to claim 1, wherein The thickness of the second organic acceptor layer is 3 to 7 nanometers; the thickness of the second organic heterojunction is 3 to 7 nanometers; the 3 to 7 nanometers.

4. The organic light emitting diode according to claim 1, wherein The LiF / Al layer consists of a LiF layer with a thickness of 1 to 2 nanometers and an Al layer with a thickness of 0.4 to 0.6 nanometers.

5. The organic light emitting diode according to claim 1, wherein The material of the electron transport layer is PO-T2T and the thickness is 32 to 38 nanometers.

6. The organic light emitting diode according to claim 1, wherein The light-emitting layer is a blue light-emitting layer, a green light-emitting layer or a red light-emitting layer; and has a thickness of 18 to 22 nanometers.

7. The organic light emitting diode according to claim 6, wherein: The blue light emitting layer uses blue light Firpic as a guest material and uses mCBP / PO-T2T exciplex as a host material.

8. The organic light emitting diode according to claim 6, wherein: The green light emitting layer uses green light Ir(ppy)2acaca as the guest material and uses TCTA as the single host light emitting carrier.

9. The organic light emitting diode according to claim 6, wherein: The red light emitting layer uses red MDQ as a guest material and TCTA as a single host light emitting carrier.

10. The organic light emitting diode according to claim 1, wherein The electron blocking layer is made of TCTA and has a thickness of 3 to 7 nanometers.

Images