CN109742250B - Organic light emitting diode and display device - Google Patents
Organic light emitting diode and display device Download PDFInfo
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- CN109742250B CN109742250B CN201811623830.4A CN201811623830A CN109742250B CN 109742250 B CN109742250 B CN 109742250B CN 201811623830 A CN201811623830 A CN 201811623830A CN 109742250 B CN109742250 B CN 109742250B
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Abstract
The invention provides an organic light emitting diode, which solves the problems that the aging of the organic light emitting diode is accelerated and the service life is reduced due to the fact that the balance of current carriers is damaged in a high-temperature environment. The method comprises the following steps: a cathode layer; an anode layer disposed on one side of the cathode layer; a plurality of charge generation layers arranged in a stacked manner in a direction perpendicular to the cathode layer, each of the charge generation layers being disposed between the cathode layer and the anode layer; and the light-emitting layer is arranged between two adjacent charge generation layers in the plurality of charge generation layers, wherein the two sides of the light-emitting layer are provided with the same type of charge generation layer.
Description
Technical Field
The invention relates to the technical field of display, in particular to an organic light emitting diode and a display device.
Background
Organic electroluminescent diodes are commercially used in small-size (mobile phones, watches, etc.) and large-size (televisions, computers, etc.) display fields because of their own characteristics of high response speed, high color purity, flexibility, etc., and are therefore often used in on-vehicle electronic devices. Since the vehicle-mounted device is often irradiated by sunlight, the vehicle-mounted device puts more stringent requirements on the organic electroluminescent diode. Under the condition that the irradiation temperature of sunlight is increased, the mobility of electrons and holes in the organic light-emitting diode is increased, but the original carrier balance is damaged due to different increasing ratios of the mobility of the electrons and the hole, and the service life is shortened.
Disclosure of Invention
In view of the above, the present invention provides an organic light emitting diode and a display device, which solve the problems of aging acceleration and service life reduction of the organic light emitting diode due to the breakdown of the balance of carriers in a high temperature environment.
An embodiment of the invention provides an organic light emitting diode and a display device, including: a cathode layer; an anode layer disposed on one side of the cathode layer; a plurality of charge generation layers arranged in a stacked manner in a direction perpendicular to the cathode layer, each of the charge generation layers being disposed between the cathode layer and the anode layer; and the light-emitting layer is arranged between two adjacent charge generation layers in the plurality of charge generation layers, wherein the two sides of the light-emitting layer are provided with the same type of charge generation layer.
In one embodiment, the plurality of charge generation layers include an electron generation layer and a hole generation layer, wherein the electron generation layer or the hole generation layer is provided on both sides of the light emitting layer.
In one embodiment, three of the charge generation layers are included, wherein each of the three charge generation layers is: a first electron generation layer disposed between the cathode layer and the light emitting layer; a first hole generation layer disposed between the anode layer and the light emitting layer; and a second electron generation layer disposed between the anode layer and the first hole generation layer; or a second hole generation layer disposed between the cathode layer and the first electron generation layer.
In one embodiment, the first electron generation layer and the second electron generation layer are made of the same material; or the first hole generation layer and the second hole generation layer are made of the same material.
In one embodiment, the first electron generation layer includes a first electron injection layer and a first electron transport layer which are stacked and arranged in a direction perpendicular to the anode layer, wherein the first electron injection layer is closer to the cathode layer than the first electron transport layer; and/or the first hole generation layer includes a first hole injection layer and a first hole transport layer which are arranged in a stacked manner in a direction perpendicular to the anode layer, wherein the first hole injection layer is closer to the anode layer than the first hole transport layer.
In one embodiment, the second electron generation layer includes a second electron transport layer and a second electron injection layer stacked in a direction perpendicular to the anode layer, wherein the second electron injection layer is closer to the first hole injection layer than the second electron transport layer; or the second hole generation layer includes a second hole transport layer and a second hole injection layer which are arranged in a stacked manner in a direction perpendicular to the anode layer, wherein the second hole injection layer is closer to the first electron injection layer than the second hole transport layer.
In one embodiment, the first electron injection layer and the second electron injection layer are made of the same material, and the first electron transport layer and the second electron transport layer are made of the same material; or the first hole injection layer and the second hole injection layer are made of the same material, and the first hole transport layer and the second hole transport layer are made of the same material.
In one embodiment, the second electron injection layer has a thickness of 1nm to 2nm, and the second electron transport layer has a thickness of 20nm to 80 nm; and/or the thickness of the second hole injection layer is 10 nm-15 nm, and the thickness of the second hole transmission layer is 40 nm-60 nm.
In one embodiment, the material of the first electron injection layer and/or the second electron injection layer is one or more of the following materials: LiF and CsF, wherein the first electron transport layer and/or the second electron transport layer are made of one or more of the following materials: 8-hydroxyquinolinoaluminum and 4-biphenol-bis (2-methyl-8-hydroxyquinolinato) aluminum; or the first hole injection layer and/or the second hole injection layer are made of one or more of the following materials: m0O3、WO3And V2O5The material of the first hole transport layer and/or the second hole transport layer is one or more of the following materials: phenylmorpholine and N, N '-diphenyl-N, N' -bis (3-methylphenyl) - (1,1 '-biphenyl) -4, 4' -diamine.
A display device comprises any one of the organic light emitting diodes.
A method for manufacturing an Organic Light Emitting Diode (OLED) is characterized by comprising the following steps: providing an anode layer; forming a first hole generation layer on the anode layer; forming a light emitting layer on the first hole generating layer; forming a first electron generation layer on the light emitting layer; and forming a cathode layer on the first electron generation layer; wherein forming a first hole generation layer on the anode layer further comprises forming a second electron generation layer on the anode layer, or forming a cathode layer on the first electron generation layer further comprises forming a second hole generation layer on the first electron generation layer.
In one embodiment, forming a first hole generation layer on the anode layer includes: forming a first hole injection layer on the anode layer, and forming a first hole transport layer on the first hole injection layer; and/or forming a first electron generation layer on the light emitting layer includes: a first electron transport layer is formed on the light emitting layer, and a first electron injection layer is formed on the first electron transport layer.
In one embodiment, when forming the second electron generation layer on the anode layer includes: forming a second electron transport layer on the anode layer, and forming the second electron injection layer on the second electron transport layer; or forming a second hole generation layer on the first electron generation layer includes: a second hole transport layer is formed on the first electron generation layer, and a second hole injection layer is formed on the second hole transport layer.
In one embodiment, the first electron injection layer and the second electron injection layer are made of the same material, and the first electron transport layer and the second electron transport layer are made of the same material; or the first hole injection layer and the second hole injection layer are made of the same material, and the first hole transport layer and the second hole transport layer are made of the same material.
The organic light emitting diode provided by the embodiment of the invention comprises a cathode layer, an anode layer and a plurality of charge generation layers, wherein the charge generation layers are arranged in a stacking mode in the direction perpendicular to the cathode layer, the charge generation layers are used for generating electrons and holes, and the charge generation layers are arranged between the cathode layer and the anode layer. The display device further comprises a light-emitting layer which is used for emitting display light and arranged between two adjacent charge generation layers in the plurality of charge generation layers, the two sides of the light-emitting layer are respectively provided with the charge generation layers of the same type, so that the electron current and the hole current on the two sides of the light-emitting layer are limited by the same charge generation layer, the transmission rates of the electron current and the hole current are the same, the electron current and the hole current are balanced, and the service life is prolonged.
Drawings
Fig. 1 is a schematic structural diagram of a display device according to an embodiment of the present invention.
Fig. 2 is a schematic structural diagram of a display device according to an embodiment of the present invention.
Fig. 3 is a schematic structural diagram of a first electron generation layer and a first hole generation layer of a display device according to an embodiment of the invention.
Fig. 4 is a schematic structural diagram of a second electron generation layer according to an embodiment of the invention.
Fig. 5 is a schematic structural diagram of a second hole generation layer according to an embodiment of the invention.
Fig. 6 is a flowchart illustrating a method for manufacturing an organic light emitting diode according to an embodiment of the invention.
Fig. 7 is a flowchart illustrating a method for manufacturing an organic light emitting diode according to an embodiment of the invention.
Fig. 8 is a flowchart illustrating a method for manufacturing an organic light emitting diode according to an embodiment of the invention.
Fig. 9 is a flowchart illustrating a method for fabricating a first hole generation layer according to an embodiment of the invention.
Fig. 10 is a flowchart illustrating a method for fabricating a first electron generation layer according to an embodiment of the invention.
Fig. 11 is a flowchart illustrating a method for fabricating a second electron generation layer according to an embodiment of the invention.
Fig. 12 is a flowchart illustrating a method for fabricating a second hole generation layer according to an embodiment of the invention.
Detailed Description
The technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the drawings in the embodiments of the present invention, and it is obvious that the described embodiments are only a part of the embodiments of the present invention, and not all of the embodiments. All other embodiments, which can be derived by a person skilled in the art from the embodiments given herein without making any creative effort, shall fall within the protection scope of the present invention.
In an embodiment of the present invention, the organic light emitting diode includes a cathode layer and an anode layer 1, and an anode layer 2, where the cathode layer 1 and the anode layer 2 are respectively used as a cathode and an anode of the organic light emitting diode to provide current for the organic light emitting diode, and the anode layer 2 is disposed on one side of the cathode layer 1. The organic light emitting diode further includes a plurality of charge generation layers stacked in a direction perpendicular to the cathode, the charge generation layers functioning to generate electrons and holes, and the charge generation layers may include an electron generation layer and a hole generation layer. The plurality of charge generation layers are each disposed between the cathode layer and the anode layer. The display device also comprises a light-emitting layer which is used for emitting display light and arranged between two adjacent charge generation layers in the plurality of charge generation layers, the two sides of the light-emitting layer are respectively provided with the charge generation layers of the same type, for example, the two sides of the light-emitting layer are respectively provided with an electron generation layer or a hole generation layer, so that the electron current and the hole current at the two sides of the light-emitting layer are both limited by the same type of charge generation layer, the transmission rates of the electron current and the hole current are the same, the electron current and the hole current are balanced, and the service life is prolonged.
It is to be understood that the light-emitting layer in the present application may be a single layer or a plurality of layers, and the present application does not limit the specific number of light-emitting layers in the organic light-emitting diode.
It can be understood that the organic light emitting diode in the present application can be used in electronic devices such as computers, mobile phones, or car navigation systems, and the present invention does not limit the specific application of the display device.
In an embodiment of the present invention, the plurality of charge generation layers may include an electron generation layer or a hole generation layer, and if the organic light emitting diode is an electronic device having a hole transport efficiency greater than an electron transport efficiency, which indicates that the electron generation layer in the organic light emitting diode has a transport efficiency less than the transport efficiency of the hole generation layer, the electron generation layers are disposed on both sides of the light emitting layer, so that the transport efficiencies of the electron current and the hole current are both limited by the electron generation layer; if the organic light-emitting diode is an electronic device with the electron transmission efficiency higher than the hole transmission efficiency, the transmission efficiency of the hole generation layer in the organic light-emitting diode is lower than that of the electron generation layer, the hole generation layers are arranged on the two sides of the light-emitting layer, so that the transmission efficiencies of the electron current and the hole current are limited by the hole generation layers; therefore, the electron current and the hole current at two sides of the luminous layer are limited by the same charge generation layer, so that the transmission rates of the electron current and the hole current are the same, the electron current and the hole current are balanced, and the service life is prolonged.
It is understood that the number of the electron generation layer and the hole generation layer on both sides of the light emitting layer can be adjusted according to actual requirements, and the present invention does not limit the number of the electron generation layer and the hole generation layer on both sides of the light emitting layer.
Fig. 1 is a schematic structural diagram of a display device according to an embodiment of the present invention. Fig. 2 is a schematic structural diagram of a display device according to an embodiment of the present invention.
As shown in fig. 1 and 2, in an embodiment of the present application, the organic light emitting diode may preferably include three charge generation layers, which are the first electron generation layer 4 and the first hole generation layer 5, the second electron generation layer 6, or the second hole generation layer 7, respectively. The organic light emitting diode may further include a light emitting layer. The first electron generation layer 4 is disposed between the cathode layer 1 and the light emitting layer 3, and the current of the cathode layer 1 forms an electron current through the first electron generation layer 4 to flow to the light emitting layer 3. The first hole generation layer 5 is disposed between the anode layer 2 and the light emitting layer 3, and a current of the anode layer 2 flows through the first hole generation layer 5 to form a hole current to flow to the light emitting layer 3. The energy generated by recombination of the electron current and the hole current in the light-emitting layer 3 causes the light-emitting material of the light-emitting layer 3 to emit display light. The organic light emitting diode further includes a second electron generation layer 6 or a second hole generation layer 7. When the organic light emitting diode is a device in which a hole current is greater than an electron current at a high temperature, the organic light emitting diode includes a second electron generation layer 6, the second electron generation layer 6 being disposed between the anode layer 2 and the first hole generation layer 5; when the organic light emitting diode is a device in which an electron current is greater than a hole current at a high temperature, the organic light emitting diode includes a second hole generation layer 7, and the second hole generation layer 7 is disposed between the cathode layer 1 and the first electron generation layer 4. Under a high-temperature environment, the mobility of both electrons and holes of the organic light emitting diode is increased, but the mobility of the electrons and the mobility of the holes are different due to the difference of materials of the first electron generation layer 4 and the first hole generation layer 5, so that the original quantity balance of the electrons and the holes is never damaged. In the organic light emitting diode with hole mobility larger than electron mobility, the second electron generation layer 6 is arranged on one side of the first hole generation layer 5, or in the organic light emitting diode with electron mobility larger than hole mobility, the second hole generation layer 7 is arranged on one side of the first electron generation layer 4, so that electron current and hole current are limited by the same material, the mobility of electrons and holes is the same, the purpose of balancing electrons and holes is achieved, and the service life of the organic light emitting diode under high temperature is prolonged.
It can be understood that the organic light emitting diode can be used in devices such as computers, mobile phones or vehicle navigation instruments, and the specific application of the organic light emitting diode is not limited in the invention.
In an embodiment of the invention, the first electron generation layer and the second electron generation layer may be made of the same material, or the first hole generation layer and the second hole generation layer may be made of the same material. Because the transmission efficiency of electric charge receives the restriction of the material of electric charge production layer, the material of different production layers is very big difference to the transmission efficiency of electric charge again, set up the material of the first electron production layer of luminescent layer both sides and second electron production layer to the same kind, or set up the material of first hole production layer and second hole production layer to the same kind, guaranteed that electron current and hole current all receive the restriction of the electric charge production layer of same kind of material, guarantee that electron current and hole current's transmission efficiency is the same, thereby balanced carrier, improve life.
It is understood that the first electron generation layer and the second electron generation layer may be made of the same material, or different materials with equal transmission efficiency may be used; the first hole generation layer and the second hole generation layer can be made of the same material, and different materials with the same transmission efficiency can also be adopted; on the premise of ensuring that the electron current and the hole current are limited by materials with the same transmission efficiency, the invention does not limit whether the materials of the first electron generation layer and the second electron generation layer are the same or not, and does not limit whether the materials of the first hole generation layer and the second hole generation layer are the same or not.
Fig. 3 is a schematic structural diagram of a first electron generation layer and a first hole generation layer of a display device according to an embodiment of the invention.
As shown in fig. 3, the first electron generation layer 4 includes a first electron injection layer 41 and a first electron transport layer 42 which are stacked and arranged in a direction perpendicular to the anode layer 2, wherein the first electron injection layer 41 is closer to the cathode layer 1 than the first electron transport layer 42. The first hole generation layer 5 includes a first hole injection layer 51 and a first hole transport layer 52 which are stacked and arranged in a direction perpendicular to the anode layer 2, and the first hole injection layer 51 is closer to the anode layer 2 than the first hole transport layer 52. The first electron injection layer 41 and the first electron transport layer 42 may transport electron current output from the cathode layer 1 to the light emitting layer 3, the first hole injection layer 51 and the first hole transport layer 52 may transport hole current output from the anode layer 2 to the light emitting layer 3, and electrons and holes meet at the light emitting layer 3 and recombine to generate energy to cause the light emitting material of the light emitting layer 3 to emit display light. Due to the existence of the first electron injection layer 41 and the first electron transport layer 42, the first hole injection layer 51 and the first hole transport layer 52, a transport path is provided for electrons and holes, and a function of emitting display light by the organic light emitting diode is realized.
It is to be understood that the number of the first electron injection layers 41 may be one or more, the number of the first electron transport layers 42 may be one or more, the number of the first hole injection layers 51 may be one or more, and the number of the first hole transport layers 52 may be one or more, and the specific numbers of the first electron injection layers 41, the first electron transport layers 42, the first hole injection layers 51, and the first hole transport layers 52 are not limited in the present invention.
It is also understood that the material of the first electron injection layer 41 may be one or more of the following materials: LiF or CsF, etc., the material of the first electron transport layer 42 may be one or more of the following materials: 8-hydroxyquinoline aluminiumOr 4-biphenol group, etc., the material of the first hole injection layer 51 may be one or more of the following materials: m0O3、WO3Or V2O5And the like, the material of the first hole transport layer 52 may be one or more of the following materials: the materials of the first electron injection layer 41, the first electron transport layer 42, the first hole injection layer 51, and the first hole transport layer 52, such as phenyl morpholine or N, N '-diphenyl-N, N' -bis (3-methylphenyl) - (1,1 '-biphenyl) -4, 4' -diamine, can be adjusted according to the actual circumstances, and the specific materials of the first electron injection layer 41, the first electron transport layer 42, the first hole injection layer 51, and the first hole transport layer 52 are not limited in the present invention.
The thickness of the first electron injection layer 41 can be 1-2 nm, the first electron injection layer 41 within the thickness range has low light absorption capacity, and can be doped with an N-type injection material with high volume concentration, so that the electron injection efficiency is effectively improved; the thickness of the first electron transmission layer 42 is 20-80 nm, the first electron transmission layer 42 in the thickness range can meet the thickness of a microcavity, an N-type transmission material with high volume concentration can be doped, the electron transmission efficiency is effectively improved, and the balance of carriers is maintained; the thickness of the first hole injection layer 51 can be 10-15 nm, the problem of transverse carrier series cannot occur in the first hole injection layer 51 within the thickness range, a P-type injection material with high volume concentration can be doped, and the hole injection efficiency is effectively improved; the thickness of the first hole transport layer 52 can be 40-60 nm, the first hole transport layer 52 in the thickness range meets the required thickness of the microcavity, a P-type transport material with high volume concentration can be doped, and the hole transport efficiency and carrier balance are effectively improved; it is also understood that the thickness of the first electron injection layer 41 may be 1nm, 1.5nm, 2nm, etc., the thickness of the first electron transport layer 42 may be 20nm, 40nm, 60nm, 80nm, etc., the thickness of the first hole injection layer 51 may be 10nm, 12nm, 15nm, etc., the thickness of the first hole transport layer 52 may be 40nm, 50nm, 60nm, etc., and the thicknesses of the first electron injection layer 41 and the first electron transport layer 42, the first hole injection layer 51, and the first hole transport layer 52 may be adjusted according to actual circumstances, and the specific thicknesses of the first electron injection layer 41 and the first electron transport layer 42, the first hole injection layer 51, and the first hole transport layer 52 are not limited in the present invention.
Fig. 4 is a schematic structural diagram of a second electron generation layer according to an embodiment of the invention.
Fig. 5 is a schematic structural diagram of a second hole generation layer according to an embodiment of the invention.
As shown in fig. 4 and 5, the second electron generation layer 6 includes a second electron transport layer 62 and a second electron injection layer 61 which are stacked and arranged in a direction perpendicular to the anode layer 2, wherein the second electron injection layer 61 is closer to the first hole injection layer 51 than the second electron transport layer 62, and the second electron injection layer 61 forms a charge generation layer after contacting the first hole injection layer 51, generating electrons and holes, thereby balancing carriers; or the second hole generation layer 7 includes a second hole transport layer 72 and a second hole injection layer 71 which are arranged in a stacked manner in a direction perpendicular to the anode layer 2, wherein the second hole injection layer 71 is closer to the first electron injection layer 41 than the second hole transport layer 72, and the second hole injection layer 71 forms a charge generation layer after contacting the first electron injection layer 41, generating electrons and holes, thereby balancing carriers. When the capacity of the first electron generation layer 4 of the organic light-emitting diode for transmitting electrons is smaller than the capacity of the first hole generation layer 5 for transmitting holes, the second electron generation layer 6 is arranged between the anode layer 2 and the first hole generation layer 5, so that the hole current generated by the anode and the electron current generated by the cathode are ensured to flow through the electron generation layer, and the electron current and the hole current are ensured to be limited by the transmission capacity of the electron generation layer; when the capacity of the first hole generation layer 5 of the organic light-emitting diode for transmitting holes is smaller than the capacity of the first electron generation layer 4 for transmitting electrons, the first hole generation layer 5 is arranged on the cathode layer 1 and the first electron generation layer 4, so that the hole current generated by the anode and the electron current generated by the cathode can flow through the hole generation layer, and the electron current and the hole current are limited by the transmission capacity of the hole generation layer. The second layer of electron generation layer or the second hole generation layer 7 is arranged on the side with large electron and hole transmission capacity, and materials with weak electron or hole transmission capacity are arranged on the two sides of the light emitting layer 3, so that electron current and hole current injected by the cathode layer 1 and the anode layer 2 are limited by the materials with weak transmission capacity, increment of the electron current and the hole current is kept consistent, carriers under the high-temperature condition are balanced, and the service life is prolonged.
It is to be understood that the second electron injection layer 61 may be one or more layers, the second electron transport layer 62 may be one or more layers, the second hole injection layer 71 may be one or more layers, and the second hole transport layer 72 may be one or more layers, and the specific materials of the first electron injection layer 41, the second electron transport layer 62, the second hole injection layer 71, and the second hole transport layer 72 are not limited in the present invention.
In an embodiment of the invention, the first electron injection layer 41 and the second electron injection layer 61 may be made of the same material, and the first electron transport layer 42 and the second electron transport layer 62 may be made of the same material; alternatively, the first hole injection layer 51 and the second hole injection layer 71 may be made of the same material, and the first hole transport layer 52 and the second hole transport layer 72 may be made of the same material. The first electron injection layer 41 and the first electron transport layer 42 constitute a first electron generation layer 4, and the second electron injection layer 61 and the second electron transport layer 62 constitute a second electron generation layer 6; the first hole injection layer 51 and the first hole injection layer 51 constitute the first hole generation layer 5, and the second hole transport layer 72 constitute the second hole generation layer 7. The first electron generation layer 4 and the second electron generation layer 6 are made of the same material, and the first hole generation layer 5 and the second hole generation layer 7 are made of the same material, so that the limitation that the electron current and the hole current can be limited by the same material is guaranteed, the increment of the electron current and the increment of the hole current are kept consistent, carriers under the high-temperature condition are balanced, and the service life is prolonged.
It is also understood that the material of the second electron injection layer 61 may be one or more of the following materials: LiF or CsF, etc., the material of the second electron transport layer 62 may be one or more of the following materials: 8-hydroxyquinoline aluminum, 4-biphenol, or the like, the material of the second hole injection layer 71 may be one or more of the following materials: m0O3、WO3Or V2O5And the like, the material of the second hole transport layer 72 may be one or more of the following materials: the materials of the second electron injection layer 61 and the second electron transport layer 62, and the second hole injection layer 71 and the second hole transport layer 72 can be adjusted according to the actual situation, and the specific materials of the second electron injection layer 61 and the second electron transport layer 62, and the second hole injection layer 71 and the second hole transport layer 72 are not limited in the present invention.
It is further understood that the thickness of the second electron injection layer 61 may be 1 to 2nm, the thickness of the second electron transport layer 62 may be 20 to 80nm, the thickness of the second hole injection layer 71 may be 10 to 15nm, the thickness of the second hole transport layer 72 may be 40 to 60nm, and the thicknesses of the second electron injection layer 61 and the second electron transport layer 62, and the thicknesses of the second hole injection layer 71 and the second hole transport layer 72 may be adjusted according to practical situations, and the specific thicknesses of the second electron injection layer 61 and the second electron transport layer 62, and the specific thicknesses of the second hole injection layer 71 and the second hole transport layer 72 are not limited in the present invention.
Fig. 6 is a flowchart illustrating a method for manufacturing an organic light emitting diode according to an embodiment of the invention.
As shown in fig. 6, a method for fabricating an organic light emitting diode includes:
step 001: providing an anode layer;
step 002: preparing at least one charge generation layer on the anode layer;
step 003: preparing a light emitting layer on the at least one charge generation layer;
step 004: when only one charge generation layer is prepared on the anode layer, a plurality of charge generation layers are also prepared on the light emitting layer; or when a plurality of charge generation layers are prepared on the anode layer, at least one charge generation layer is also prepared on the light-emitting layer;
step 005: a cathode is prepared on the charge generation layer on the light emitting layer.
The two sides of the light-emitting layer are required to be ensured to be provided with the same type of charge generation layer, so that the electron current and the hole current at the two sides of the light-emitting layer are limited by the same type of charge generation layer, the transmission rates of the electron current and the hole current are the same, the electron current and the hole current are balanced, and the service life is prolonged.
The types of the charge generation layer can be an electron generation layer and a hole generation layer, and it can be understood that the specific number of the electron generation layer and the hole generation layer on the two sides of the light emitting layer can be adjusted according to actual conditions, and only the electron generation layer and the hole generation layer on the two sides of the light emitting layer are required to be ensured.
Fig. 7 is a flowchart illustrating a method for manufacturing an organic light emitting diode according to an embodiment of the invention. Fig. 8 is a flowchart illustrating a method for manufacturing an organic light emitting diode according to an embodiment of the invention.
As shown in fig. 7 and 8, preferably, the method of fabricating the organic light emitting diode includes:
step 01: providing an anode layer 2;
step 02: forming a first hole generation layer 5 on the anode layer 2;
step 03: forming a light-emitting layer 3 on the first hole generation layer 5;
step 04: forming a first electron generation layer 4 on the light emitting layer 3;
step 05: a cathode layer 1 is formed on the first electron generation layer 4.
Wherein, if the first electron generation layer 4 of the organic light emitting diode has a weaker ability to transport electrons and holes than the first hole generation layer 5, the step 06 of forming the first hole generation layer 5 on the anode layer 2 further comprises: forming a second electron generation layer 6 on the anode layer 2; alternatively, if the first electron generation layer 4 of the organic light emitting diode has a stronger ability to transport electrons and holes than the first hole generation layer 5, step 07 is further included before forming the cathode layer 1 on the first electron generation layer 4: a second hole generation layer 7 is formed on the first electron generation layer 4. In a high-temperature environment, the mobility of electrons and holes in the device is increased, but the mobility of electrons and holes is different due to the difference of materials of the first electron generation layer 4 and the first hole generation layer 5, so that the original quantity of electrons and holes is never destroyed. In the device with the hole mobility larger than the electron mobility, the second electron generation layer 6 is arranged on one side of the first hole generation layer 5, or in the device with the electron mobility larger than the hole mobility, the second hole generation layer 7 is arranged on one side of the first electron generation layer 4, so that the electron current and the hole current are limited by the same material, the mobility of the electron and the hole is the same, the purpose of balancing the electron and the hole is achieved, and the service life of the organic light emitting diode under the high-temperature condition is prolonged.
It can be understood that the process for forming each functional layer in the process of preparing the organic light emitting diode in the present invention may adopt vacuum evaporation, and may also adopt other processes for preparation.
Fig. 9 is a flowchart illustrating a method for fabricating a first hole generation layer according to an embodiment of the invention.
As shown in fig. 9, forming the first hole generation layer 5 on the anode layer 2 includes:
step 08: forming a first hole injection layer 51 on the anode layer 2;
step 09: a first transport layer is formed on the first hole injection layer 51.
Fig. 10 is a flowchart illustrating a method for fabricating a first electron generation layer according to an embodiment of the invention.
As shown in fig. 10, forming the first electron generation layer 4 on the light emitting layer 3 includes:
step 10: forming a first electron transport layer 42 on the light emitting layer 3;
step 11: the first electron injection layer 41 is formed on the first electron transport layer 42.
The first electron injection layer 41 and the first electron transport layer 42, the first hole injection layer 51 and the first hole transport layer 52 are prepared to provide a transport path for electrons and holes, and thus, a function of emitting display light of the organic light emitting diode is realized.
Fig. 11 is a flowchart illustrating a method for fabricating a second electron generation layer according to an embodiment of the invention.
As shown in fig. 11, forming the second electron generation layer 6 on the anode layer 2 includes:
step 12: forming a second electron transport layer 62 on the anode layer 2;
step 13: a second electron injection layer 61 is formed on the second electron transport layer 62.
Fig. 12 is a flowchart illustrating a method for fabricating a second hole generation layer according to an embodiment of the invention.
As shown in fig. 12, forming the second hole generation layer 7 on the first electron generation layer 4 includes:
step 14: forming a second hole transport layer 72 on the first electron generation layer 4;
step 15: the second hole injection layer 71 is formed on the second hole transport layer 72.
When the first electron generation layer 4 of the organic light emitting diode has a smaller ability to transport electrons than the first hole generation layer 5, a second electron generation layer 6 is disposed between the anode layer 2 and the first hole generation layer 5; when the first hole generation layer 5 of the organic light emitting diode has a smaller ability to transport holes than the first electron generation layer 4, the first hole generation layer 5 is provided between the cathode layer 1 and the first electron generation layer 4. The second layer of electron generation layer or the second hole generation layer 7 is arranged on the side with large electron and hole transmission capacity, and materials with weak electron and hole transmission capacity are arranged on the two sides of the light emitting layer 3, so that electron current and hole current injected into the cathode layer 1 and the anode layer 2 are limited by the materials with weak transmission capacity, increment of the electron current and the hole current is kept consistent, carriers under the high-temperature condition are balanced, and the service life is prolonged.
It is understood that the material of the first electron injection layer 41 may be the same as or different from that of the second electron injection layer 61; the material of the first electron transport layer 42 may be the same as or different from that of the second electron transport layer 62; the material of the first hole injection layer 51 may be the same as or different from that of the second hole injection layer 71; the material of the first hole transport layer 52 may be the same as or different from that of the second hole transport layer 72. The material of the first electron injection layer 41 may be the same as that of the second electron injection layer 61, the material of the first electron transport layer 42 may be the same as that of the second electron transport layer 62, the material of the first hole injection layer 51 may be the same as that of the second hole injection layer 71, and the material of the first hole transport layer 52 may be the same as that of the second hole transport layer 72, so that it can be ensured that the electron current and the hole current are limited by the same material, and the mobility of the electrons and the holes is the same, thereby achieving the purpose of balancing the electrons and the holes, and thus prolonging the service life of the organic light emitting diode under high temperature conditions. However, in consideration of practical conditions such as cost and process, the materials of the first electron injection layer 41 and the second electron injection layer 61, the first electron transport layer 42 and the second electron transport layer 62, the first hole injection layer 51 and the second hole injection layer 71, and the first hole transport layer 52 and the second hole transport layer 72 may be set to be different from each other on the premise that the carrier balance can be ensured.
In an embodiment of the present invention, the display device includes the organic light emitting diode mentioned in the present application, and since both sides of the light emitting layer in the organic light emitting diode are limited by the same material of the same charge generation layer, the transmission efficiency of the electron current and the hole current is ensured to be equal, and the service life is prolonged. It is understood that the display device may further include a driving layer, an encapsulation layer, a polarizer layer, a touch layer, etc., the type of the functional layers included in the display device may be adjusted according to actual requirements, and the specific functional layers included in the display device are not limited in the present invention.
The above description is only for the purpose of illustrating the preferred embodiments of the present invention and is not to be construed as limiting the invention, and any modifications, equivalents and the like that are within the spirit and principle of the present invention are included in the present invention.
Claims (9)
1. An organic light emitting diode, comprising:
a cathode layer;
an anode layer disposed on one side of the cathode layer;
a plurality of charge generation layers arranged in a stacked manner in a direction perpendicular to the cathode layer, each of the charge generation layers being disposed between the cathode layer and the anode layer;
a light emitting layer disposed between two adjacent charge generation layers among the plurality of charge generation layers, wherein both sides of the light emitting layer are provided with the same type of charge generation layer,
the plurality of charge generation layers includes three of the charge generation layers, the three of the charge generation layers including:
a first electron generation layer disposed between the cathode layer and the light emitting layer;
a first hole generation layer disposed between the anode layer and the light emitting layer; and
when the organic light emitting diode is a device with a hole current larger than an electron current at high temperature, the three charge generation layers further comprise a second electron generation layer arranged between the anode layer and the first hole generation layer, or
When the organic light emitting diode is a device in which an electron current is larger than a hole current at a high temperature, the three charge generation layers further include a second hole generation layer disposed between the cathode layer and the first electron generation layer,
the second electron generation layer or the second hole generation layer is used to make the mobility of electrons and holes at both sides of the light emitting layer the same.
2. The organic light-emitting diode according to claim 1, wherein the plurality of charge generation layers include an electron generation layer and a hole generation layer, and wherein the electron generation layer or the hole generation layer is provided on both sides of the light-emitting layer.
3. The OLED of claim 1, wherein the first and second electron generation layers are made of the same material; or
The first hole generation layer and the second hole generation layer are made of the same material.
4. The organic light-emitting diode of claim 1, wherein the first electron generation layer comprises a first electron injection layer and a first electron transport layer arranged in a stacked manner in a direction perpendicular to the anode layer, wherein the first electron injection layer is closer to the cathode layer than the first electron transport layer; and/or
The first hole generation layer includes a first hole injection layer and a first hole transport layer which are arranged in a stacked manner in a direction perpendicular to the anode layer, wherein the first hole injection layer is closer to the anode layer than the first hole transport layer.
5. The organic light-emitting diode according to claim 4, wherein the second electron generation layer comprises a second electron transport layer and a second electron injection layer which are arranged in a stacked manner in a direction perpendicular to the anode layer, wherein the second electron injection layer is closer to the first hole injection layer than the second electron transport layer; or
The second hole generation layer includes a second hole transport layer and a second hole injection layer that are stacked in a direction perpendicular to the anode layer, wherein the second hole injection layer is closer to the first electron injection layer than the second hole transport layer.
6. The OLED of claim 5, wherein the first electron injection layer and the second electron injection layer are made of the same material, and the first electron transport layer and the second electron transport layer are made of the same material; or
The first hole injection layer and the second hole injection layer are made of the same material, and the first hole transport layer and the second hole transport layer are made of the same material.
7. The OLED of claim 5, wherein the second electron injection layer has a thickness of 1nm to 2nm, and the second electron transport layer has a thickness of 20nm to 80 nm; and/or
The thickness of the second hole injection layer is 10 nm-15 nm, and the thickness of the second hole transmission layer is 40 nm-60 nm.
8. The OLED as claimed in claim 5, wherein the first and/or second electron injection layers are made of one or more of the following materials: LiF and CsF, wherein the first electron transport layer and/or the second electron transport layer are made of one or more of the following materials: 8-hydroxyquinolinoaluminum and 4-biphenol-bis (2-methyl-8-hydroxyquinolinato) aluminum; or
The first hole injection layer and/or the second hole injection layer are made of one or more of the following materials: m0O3、WO3And V2O5The material of the first hole transport layer and/or the second hole transport layer is one or more of the following materials: phenylmorpholine and N, N '-diphenyl-N, N' -bis (3-methylphenyl) - (1,1 '-biphenyl) -4, 4' -diamine.
9. A display device comprising the organic light emitting diode according to any one of claims 1 to 8.
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