Display panel, organic light-emitting diode and manufacturing method therefor

Abstract

A display panel, an organic light-emitting diode and a manufacturing method therefor, relating to the technical field of displays. The organic light-emitting diode comprises anodes (AE), a light-emitting function unit (EFU), and a cathode (CE) that are sequentially stacked. The EFU comprises at least one light-emitting stack structure (ELS), and each ELS comprises a light-emitting unit (LU), wherein at least one LU comprises an auxiliary light-emitting layer (AEML) and a light-emitting layer (EML) that are sequentially stacked in a direction moving from the AE to the CE, and the components of the AEML are part of the components of the EML. The organic light-emitting diode can reduce the manufacturing costs and process difficulty.

Description

Display panel, organic light emitting diode and preparation method thereof

[0001] Cross-reference to related applications

[0002] The present disclosure claims priority to Chinese Patent Application No. 202410572725.1, filed May 9, 2024, entitled “Display panel, organic light emitting diode and preparation method thereof,” the entire contents of which are incorporated herein by reference in its entirety. TECHNICAL FIELD

[0003] The present disclosure relates to the technical field of display, in particular, to a display panel, an organic light emitting diode and a preparation method thereof. BACKGROUND

[0004] The sensitized fluorescent technology has the advantages of high efficiency of the sensitizing agent (such as phosphorescence or TADF (thermally activated delayed fluorescence)) and high color purity of the fluorescent emitter, and thus has more technical advantages in the display field than the current fluorescent and phosphorescent technologies.

[0005] At present, the device structure of this system is more complex than that of the ordinary fluorescent device, especially for the application of the tandem structure, additional evaporation equipment is needed, which increases the process difficulty and cost of production and manufacturing.

[0006] It should be noted that the information disclosed in the above background section is only used to strengthen the understanding of the background of the present disclosure, and thus can include information that does not constitute prior art known to those of ordinary skill in the art. SUMMARY

[0007] The purpose of the present disclosure is to overcome the shortcomings of the prior art, and to provide a display panel, an organic light emitting diode and a preparation method thereof, so as to reduce the manufacturing process difficulty and cost.

[0008] According to one aspect of the present disclosure, an organic light emitting diode is provided, comprising an anode, a light emitting functional unit and a cathode which are sequentially stacked.

[0009] The light emitting functional unit comprises at least one light emitting stack structure, each of which comprises a light emitting unit; wherein at least one light emitting unit comprises an auxiliary light emitting layer and a light emitting layer which are sequentially stacked in the direction from the anode to the cathode.

[0010] The composition of the auxiliary light emitting layer is part of the composition of the light emitting layer.

[0011] In an embodiment of the present disclosure, the light emitting functional unit comprises at least two light emitting stack structures which are sequentially stacked.

[0012] In an embodiment of the present disclosure, the light-emitting layer comprises a hole-transporting host material, a thermally activated delayed fluorescence material, and a guest dopant material.

[0013] The auxiliary light-emitting layer comprises a hole-transporting host material and a guest dopant material.

[0014] In an embodiment of the present disclosure, the light-emitting unit further comprises an adjustment layer, and the light-emitting stack structure further comprises a hole-transporting layer located on the side of the light-emitting unit close to the anode, and the hole-transporting layer is located adjacent to the adjustment layer.

[0015] The light-emitting functional unit comprises a first light-emitting stack structure and a second light-emitting stack structure located adjacent to and stacked with each other; the first light-emitting stack structure comprises a hole-transporting layer, an adjustment layer, an auxiliary light-emitting layer, and a light-emitting layer located sequentially and stacked with each other; and the second light-emitting stack structure comprises a hole-transporting layer, an adjustment layer, an auxiliary light-emitting layer, and a light-emitting layer located sequentially and stacked with each other.

[0016] The absolute value of the highest occupied molecular orbital energy level of the hole-transporting layer of the first light-emitting stack structure is less than the absolute value of the highest occupied molecular orbital energy level of the hole-transporting layer of the second light-emitting stack structure, and the thickness of the adjustment layer of the first light-emitting stack structure is greater than the thickness of the adjustment layer of the second light-emitting stack structure.

[0017] In an embodiment of the present disclosure, the light-emitting stack structure further comprises a hole-transporting layer located on the side of the light-emitting unit close to the anode.

[0018] The light-emitting functional unit comprises a third light-emitting stack structure and a fourth light-emitting stack structure located adjacent to and stacked with each other; the third light-emitting stack structure comprises a hole-transporting layer, an adjustment layer, an auxiliary light-emitting layer, and a light-emitting layer located sequentially and stacked with each other; and the fourth light-emitting stack structure comprises a hole-transporting layer, an auxiliary light-emitting layer, and a light-emitting layer located sequentially and stacked with each other.

[0019] The absolute value of the highest occupied molecular orbital energy level of the hole-transporting layer of the third light-emitting stack structure is less than the absolute value of the highest occupied molecular orbital energy level of the hole-transporting layer of the fourth light-emitting stack structure.

[0020] In an embodiment of the present disclosure, the organic light-emitting diode comprises a plurality of light-emitting stack structures located sequentially and stacked with each other.

[0021] Any one of the light-emitting stack structures comprises a hole-transporting layer, an adjustment layer, an auxiliary light-emitting layer, and a light-emitting layer located sequentially and stacked with each other; and the absolute value of the difference between the highest occupied molecular orbital energy level of the hole-transporting layer and the highest occupied molecular orbital energy level of the hole-transporting host material in the light-emitting layer is not less than 0.25 eV.

[0022] The hole transport layer in two adjacent light-emitting stack structures is made of the same material;

[0023] The light-emitting functional unit comprises a fifth light-emitting stack structure and a sixth light-emitting stack structure arranged adjacently and in a stack; the distance between the fifth light-emitting stack structure and the anode is smaller than the distance between the sixth light-emitting stack structure and the anode;

[0024] The sum of the thicknesses of the hole transport layer and the adjustment layer of the fifth light-emitting stack structure is greater than the sum of the thicknesses of the hole transport layer and the adjustment layer of the sixth light-emitting stack structure.

[0025] In an embodiment of the present disclosure, the organic light-emitting diode comprises a plurality of light-emitting stack structures arranged in a stack;

[0026] Any one of the light-emitting stack structures comprises a hole transport layer, an adjustment layer, an auxiliary light-emitting layer and a light-emitting layer arranged in a stack; the absolute value of the difference between the highest occupied molecular orbital energy level of the hole transport layer and the highest occupied molecular orbital energy level of the hole transport type host material in the light-emitting layer is not less than 0.25 eV;

[0027] The hole transport layer in two adjacent light-emitting stack structures is made of the same material;

[0028] The light-emitting functional unit comprises a seventh light-emitting stack structure and an eighth light-emitting stack structure arranged adjacently and in a stack; the distance between the seventh light-emitting stack structure and the anode is smaller than the distance between the eighth light-emitting stack structure and the anode;

[0029] The thickness of the hole transport layer of the seventh light-emitting stack structure is large, and the thickness of the adjustment layer is small.

[0030] In an embodiment of the present disclosure, the thickness of the auxiliary light-emitting layer is smaller than the thickness of the light-emitting layer.

[0031] In an embodiment of the present disclosure, the light-emitting stack structure further comprises a hole blocking layer located on the side of the light-emitting unit away from the anode;

[0032] The difference between the energy value of the first triplet energy level of the hole blocking layer and the energy value of the first triplet energy level of the thermally activated delayed fluorescence material in the light-emitting layer is not less than 0.2 eV.

[0033] In an embodiment of the present disclosure, the overlap area of the emission spectrum of the thermally activated delayed fluorescence material in the light-emitting layer and the absorption spectrum of the guest doped material is not less than 60% of the absorption spectrum area of the guest doped material.

[0034] In an embodiment of the present disclosure, the difference between the energy value of the first triplet energy level of the hole transport type host material in the light-emitting layer and the energy value of the first triplet energy level of the thermally activated delayed fluorescence material is not less than 0.1 eV.

[0035] According to another aspect of the present disclosure, a display panel is provided, comprising arrayed organic light-emitting diodes; wherein at least one of the organic light-emitting diodes is selected from the above-mentioned organic light-emitting diodes.

[0036] In an embodiment of the present disclosure, the display panel comprises a red organic light-emitting diode, a green organic light-emitting diode and a blue organic light-emitting diode, and the green organic light-emitting diode is selected from the above-mentioned organic light-emitting diodes.

[0037] According to another aspect of the present disclosure, a preparation method of an organic light-emitting diode is provided, comprising an anode, a light-emitting functional unit and a cathode which are sequentially stacked;

[0038] The light-emitting functional unit comprises at least one light-emitting stack structure, and each of the light-emitting stack structures comprises one light-emitting unit; wherein at least one of the light-emitting units comprises an auxiliary light-emitting layer and a light-emitting layer which are sequentially stacked in the direction from the anode to the cathode; and the components of the auxiliary light-emitting layer are part of the components of the light-emitting layer.

[0039] The forming of the at least one light-emitting unit comprises:

[0040] forming the auxiliary light-emitting layer by evaporation in an evaporation chamber;

[0041] forming the light-emitting layer by evaporation in the same evaporation chamber.

[0042] In an embodiment of the present disclosure, the forming of the auxiliary light-emitting layer by evaporation in the evaporation chamber comprises:

[0043] putting the targets of the components required for forming the light-emitting layer into the evaporation chamber;

[0044] shielding the targets of the components not contained in the auxiliary light-emitting layer and exposing the other targets; and evaporating the exposed targets to form the auxiliary light-emitting layer;

[0045] exposing the targets in the evaporation chamber to evaporate the exposed targets to form the light-emitting layer.

[0046] It should be understood that the above general description and the following detailed description are only exemplary and explanatory, and cannot limit the present disclosure. BRIEF DESCRIPTION OF DRAWINGS

[0047] The accompanying drawings, which are incorporated herein and constitute part of this specification, illustrate embodiments consistent with the present disclosure and, together with the description, further serve to explain the principles of the present disclosure. It is to be understood that the drawings are only schematic, and that they do not necessarily represent a limiting case of the application. In the drawings:

[0048] FIG. 1 is a schematic diagram of a structure of a display panel according to an embodiment of the present disclosure.

[0049] FIG. 2 is a schematic diagram of a structure of a display panel according to an embodiment of the present disclosure.

[0050] FIG. 3 is a schematic diagram of a structure of a display panel according to an embodiment of the present disclosure.

[0051] FIG. 4 is a schematic diagram of a structure of an organic light emitting diode according to an embodiment of the present disclosure.

[0052] FIG. 5 is a schematic diagram of a structure of an organic light emitting diode according to an embodiment of the present disclosure.

[0053] FIG. 6 is a schematic diagram of a structure of a display panel according to an embodiment of the present disclosure.

[0054] FIG. 7 is a schematic diagram of a structure of a display panel according to an embodiment of the present disclosure. DETAILED DESCRIPTION

[0055] Example implementations will now be described more fully with reference to the accompanying drawings. Example implementations can be implemented in any number of ways, and are not limited to the implementations set forth herein; rather, implementations should be construed broadly as encompassing any implementation that is within the scope of the present disclosure, even if that implementation is not set forth in the present description. The same reference numerals in different drawings represent the same or similar elements.

[0056] Although relative terms such as "upper," "lower," etc. are used herein to describe one component's relationship to another component of a device, such terminology is used for convenience only when describing the device as oriented in the example shown in the drawings. It is to be understood that if the device were inverted, then what is described as the "upper" component would be the "lower" component. When a structure is "on" or "under" another structure, that structure can be directly on or under the other structure or, alternatively, intervening structures can also be present.

[0057] The terms "one", "a", "an", "the", and "at least one" are used to indicate that "one or more" of something is / are present; the terms "includes" and "including" are used to indicate an open-ended include in that additional items can be present other than those listed; the terms "first", "second", and the like, are used merely as labels, and are not intended to impose numerical requirements on their objects.

[0058] The structure layer Q1 is located on the side of the structure layer Q2 away from the substrate, which can be understood as that the structure layer Q1 is formed on the side of the structure layer Q2 away from the substrate. When the structure layer Q2 is a patterned structure, part of the structure of the structure layer Q1 can also be located at the same physical height as the structure layer Q2 or below the physical height of the structure layer Q2, wherein the substrate is the height reference.

[0059] The display panel provided by the embodiment of the present disclosure, as shown in FIG. 1, includes a display area AA and a peripheral area BB located on at least one side of the display area AA, for example, the peripheral area BB surrounds the display area AA. In the display area AA, the display panel PNL is provided with sub-pixels for display; in the peripheral area BB, the display panel PNL can not be provided with sub-pixels for display, or the sub-pixels provided are not used for displaying pictures.

[0060] In the embodiment of the present disclosure, as shown in FIG. 2, the sub-pixels in the display panel PNL are thin-film self-luminous light-emitting elements LD, for example, OLED and the like. Further, the light-emitting elements LD located in the display area AA include light-emitting elements LD of multiple different colors. For example, the light-emitting elements LD can include red light-emitting elements RLD for emitting red light, blue light-emitting elements BLD for emitting blue light, and green light-emitting elements GLD for emitting green light. It can be understood that in other embodiments of the present disclosure, the light-emitting elements LD in the display area AA can also be light-emitting elements LD of only one color, or can also have light-emitting elements LD of other colors (for example, yellow light-emitting elements for emitting yellow light, cyan light-emitting elements for emitting cyan light, white light-emitting elements for emitting white light, etc.).

[0061] In the embodiment of the present disclosure, as shown in FIG. 2, the display panel PNL can include a driving backplane DBP and a pixel layer PIXL which are sequentially stacked, the pixel layer PIXL is provided with light-emitting elements LD, and the driving backplane DBP is used to drive the light-emitting elements LD in the pixel layer PIXL. Wherein, the driving backplane DBP can drive each light-emitting element LD in an active driving manner, or can drive each light-emitting element LD in a passive driving manner.

[0062] In the embodiment of the present disclosure, referring to FIG. 2, the driving back plate DBP includes a substrate BP and a driving layer DRL disposed on one side of the substrate BP; and the pixel layer PIXL is disposed on the side of the driving layer DRL away from the substrate BP. The driving layer DRL is provided with a pixel driving circuit PDC for driving the light emitting element LD; and each light emitting element LD can emit light under the driving of the pixel driving circuit PDC to display a picture. Further, the display panel PNL further includes a thin film encapsulation layer TFE located on the side of the pixel layer PIXL away from the driving back plate DBP, and the thin film encapsulation layer TFE can encapsulate and protect the pixel layer PIXL.

[0063] In the embodiment of the present disclosure, the substrate BP can be a substrate of inorganic material, or a substrate of organic material; of course, it can also be a composite substrate formed by laminating a substrate of inorganic material and a substrate of organic material. For example, in some embodiments of the present disclosure, the material of the substrate BP can be a glass material such as soda lime glass, quartz glass, sapphire glass, etc. In some other embodiments of the present disclosure, the material of the substrate BP can be polymethyl methacrylate, polyvinyl alcohol, polyvinyl phenol, polyether sulfone, polyimide, polyamide, polyacetal, polycarbonate, polyethylene terephthalate, polyethylene naphthalate, or a combination thereof. In some other embodiments of the present disclosure, the substrate BP can also be a flexible substrate, for example, the material of the substrate BP can include polyimide.

[0064] In the embodiment of the present disclosure, in the driving layer DRL, any one pixel driving circuit PDC can include a thin film transistor and a storage capacitor. Further, the thin film transistor can be selected from a top-gate thin film transistor, a bottom-gate thin film transistor, or a dual-gate thin film transistor; the material of the active layer of the thin film transistor can be amorphous silicon semiconductor material, low-temperature polysilicon semiconductor material, metal oxide semiconductor material, organic semiconductor material, carbon nanotube semiconductor material, or other types of semiconductor material; and the thin film transistor can be an N-type thin film transistor or a P-type thin film transistor.

[0065] It can be understood that in each of the pixel driving circuit PDC, the types of any two transistors can be the same or different. Exemplarily, in some embodiments, in one pixel driving circuit PDC, part of the transistors can be N-type transistors and part of the transistors can be P-type transistors. Further exemplarily, in some other embodiments, in one pixel driving circuit PDC, the material of the active layer of part of the transistors can be low-temperature polysilicon semiconductor material and the material of the active layer of part of the transistors can be metal oxide semiconductor material. In some embodiments of the present disclosure, the thin film transistor is a low-temperature polysilicon transistor. In some other embodiments of the present disclosure, part of the thin film transistors are low-temperature polysilicon transistors and part of the thin film transistors are metal oxide transistors.

[0066] In the embodiments of the present disclosure, referring to FIG. 3, the driving layer DRL can include a semiconductor layer SCL, a gate insulating layer GI, a gate layer GT, an interlayer dielectric layer ILD, a source-drain metal layer SD, a planarization layer PLN, etc. which are laminated between the substrate base plate BP and the pixel layer PIXL. Each thin film transistor and storage capacitor can be formed by the semiconductor layer SCL, the gate insulating layer GI, the gate layer GT, the interlayer dielectric layer ILD, the source-drain metal layer SD, etc. The positional relationship of each film layer can be determined according to the film layer structure of the thin film transistor. Further, the semiconductor layer SCL can be used to form the channel region of the transistor and can also be used to form part of the wiring or conductive structure by being conductive if necessary. The gate layer GT can be used to form one or more of the gate layer wiring such as the scan wiring, the reset control wiring, the light-emitting control wiring, etc., can also be used to form the gate of the transistor, and can also be used to form part or all of the electrode plate of the storage capacitor. The source-drain metal layer SD can be used to form the source-drain metal layer wiring such as the data wiring, the driving power voltage wiring, etc., and can also be used to form part of the electrode plate of the storage capacitor. Of course, in other embodiments of the present disclosure, the driving layer DRL can also include other film layers as needed, for example, it can also include a light shielding layer, an inorganic buffer layer BUF, etc. between the semiconductor layer SCL and the substrate base plate BP. Any one of the above-mentioned film layers such as the semiconductor layer SCL, the gate layer GT, the source-drain metal layer SD, etc. can also be multi-layered as needed, for example, the driving layer DRL can include two different semiconductor layers SCL, or two or three source-drain metal layers SD, or two or three gate layers GT; accordingly, the insulating film layers in the driving layer DRL (such as the gate insulating layer GI, the interlayer dielectric layer ILD, the planarization layer PLN, etc.) can be adaptively increased or reduced, or new insulating film layers can be added as needed.

[0067] In the embodiment of the present disclosure, the driving layer DRL can further comprise a passivation layer, which can be arranged on the surface of the source-drain metal layer SD away from the substrate BP, so as to protect the source-drain metal layer SD.

[0068] As an example, referring to FIG. 3, the driving layer DRL can comprise an inorganic buffer layer BUF, a semiconductor layer SCL, a gate insulating layer GI, a gate layer GT, an interlayer dielectric layer ILD, a source-drain metal layer SD and a planarization layer PLN arranged in sequence, and the thin film transistor thus formed is a top-gate type thin film transistor.

[0069] It can be understood that the above example of the driving backplane DBP is only one possible way of the driving backplane DBP in the embodiment of the present disclosure. In other embodiments of the present disclosure, the driving backplane DBP can also have other structures, for example, the driving backplane DBP can also be a passive driving glass substrate, a silicon-based driving substrate, etc.

[0070] In the embodiment of the present disclosure, referring to FIG. 3, the light emitting element LD in the pixel layer PIXL is a thin film type light emitting element, which can comprise two electrodes arranged in sequence and a light emitting functional unit EFU sandwiched between the two electrodes. For example, referring to FIG. 3, the pixel layer PIXL can comprise a pixel electrode layer PEL, a light emitting functional layer EFL and a common electrode layer COML arranged in sequence. The pixel electrode layer PEL has a plurality of pixel electrodes PE in the display area AA of the display panel PNL; the light emitting functional layer EFL has a part connected with the pixel electrode PE as the light emitting functional unit EFU of the light emitting element LD, and the common electrode layer COML is electrically connected with the light emitting functional unit EFU of each light emitting element LD as a common electrode.

[0071] Further, the pixel layer PIXL can further include a pixel definition layer PDL located between the pixel electrode layer PEL and the light-emitting functional layer EFL. The pixel definition layer PDL has a plurality of through pixel openings arranged one-to-one corresponding to the plurality of pixel electrodes PE, and any one pixel opening exposes at least a partial region of the corresponding pixel electrode PE. For example, the pixel definition layer PDL covers the edges of the pixel electrode PE and exposes at least a partial internal region of the pixel electrode PE, so that the pixel definition layer PDL can effectively define the actual effective region (the region directly connected to the light-emitting functional unit EFU) of the pixel electrode PE, and further define the light-emitting region and the light-emitting area of the light-emitting element LD. The light-emitting functional layer EFL at least covers the pixel electrode PE exposed by the pixel definition layer PDL. The common electrode layer COML can cover the light-emitting functional layer EFL in the display area AA. The pixel electrode PE and the common electrode layer COML provide carriers such as electrons and holes to the light-emitting functional layer EFL, so that the light-emitting functional layer EFL emits light. The part of the light-emitting functional layer EFL located between the pixel electrode PE and the common electrode layer COML can serve as a light-emitting functional unit EFU. The pixel electrode PE, the common electrode layer COML, and the light-emitting functional unit EFU form the light-emitting element LD. Among them, one of the pixel electrode PE and the common electrode layer COML serves as an anode of the light-emitting element LD, and the other serves as a cathode of the light-emitting element LD.

[0072] In an example, the pixel electrode PE serves as an anode of the light-emitting element LD, and the common electrode layer COML serves as a cathode of the light-emitting element LD.

[0073] In the embodiments of the present disclosure, referring to FIG. 3, the thin film encapsulation layer TFE can be arranged on the surface of the pixel layer PIXL away from the substrate BP, which can include inorganic encapsulation layers and organic encapsulation layers arranged alternately. The inorganic encapsulation layer can effectively block moisture and oxygen from the outside, so as to avoid water and oxygen from invading the pixel layer PIXL and causing the material in the pixel layer PIXL to age. Optionally, the edges of the inorganic encapsulation layer can be located in the peripheral area. The organic encapsulation layer is located between two adjacent inorganic encapsulation layers, so as to achieve planarization and weaken the stress between the inorganic encapsulation layers. Among them, the edges of the organic encapsulation layer can be located between the edges of the display area and the edges of the inorganic encapsulation layer. For example, the thin film encapsulation layer TFE includes a first inorganic encapsulation layer CVD1, an organic encapsulation layer IJP, and a second inorganic encapsulation layer CVD2 arranged in sequence on the side of the pixel layer PIXL away from the substrate BP. Of course, in other embodiments of the present disclosure, the display panel can also not be provided with a thin film encapsulation layer, but other ways can be used to encapsulate and protect the pixel layer.

[0074] In some embodiments of the present disclosure, referring to FIG. 3, the display panel PNL can further include a touch buffer layer TSL, which can be disposed on the side of the thin film encapsulation layer TFE away from the driving backplane DBP, so that the display panel PNL has a touch function. For example, the touch buffer layer TSL includes a touch buffer layer TBUF, a first touch metal layer TMA, a touch dielectric layer TLD, and a second touch metal layer TMB, which are sequentially stacked on the side of the thin film encapsulation layer TFE away from the substrate substrate BP.

[0075] In some embodiments of the present disclosure, the display panel PNL can further include a color film layer (not shown in the figure), which can be disposed on the side of the thin film encapsulation layer TFE away from the driving backplane DBP, so as to reduce the reflection of ambient light and improve the display quality.

[0076] In some embodiments of the present disclosure, the types of light emitting elements LD are different, and the materials and film layers of the light emitting functional units EFU are different.

[0077] Referring to FIG. 4, when the light emitting element LD is an OLED, the light emitting functional unit EFU can include an organic light emitting layer EML, and can include one or more of a hole injection layer HIL, a hole transport layer HTL, an electron blocking layer EBL, a hole blocking layer HBL, an electron transport layer ETL, and an electron injection layer EIL. Referring to FIG. 5, when the OLED adopts a stacked structure, a charge generation layer CGL can also be disposed in the light emitting functional layer EFL.

[0078] In the embodiments of the present disclosure, the light emitting functional unit EFU can include one light emitting stacked structure ELS, or can include a plurality of light emitting stacked structures ELS stacked together. Referring to FIG. 5, when the light emitting functional unit EFU includes a plurality of light emitting stacked structures ELS, a charge generation layer CGL can be disposed between any two adjacent light emitting stacked structures ELS. Each light emitting stacked structure ELS includes one or more light emitting layers, which can be an organic light emitting layer EML.

[0079] In the embodiments of the present disclosure, referring to FIG. 4, the light-emitting functional unit EFU has a light-emitting stack structure ELS. The light-emitting element LD includes an anode AE, the light-emitting stack structure ELS, and a cathode CE, which are sequentially stacked. The light-emitting stack structure ELS includes a hole adjustment layer, a light-emitting layer (for example, EML), and an electron adjustment layer, which are sequentially stacked. The hole adjustment layer is located on the side of the light-emitting layer close to the anode AE, and the electron adjustment layer is located on the side of the light-emitting layer close to the cathode CE. The anode AE is configured to inject holes into the light-emitting layer through the hole adjustment layer, and the cathode CE is configured to inject electrons into the light-emitting layer through the electron adjustment layer. The hole adjustment layer and the electron adjustment layer are respectively configured to adjust the injection efficiency and injection speed of the holes and the electrons injected into the light-emitting layer, and to adjust the energy level of the injected electrons and holes, so as to improve the balance of hole injection and electron injection, thereby improving the performance of the light-emitting functional unit EFU, for example, one or more of improving the light-emitting efficiency of the light-emitting element LD, improving the device lifetime of the light-emitting element LD, and reducing the power supply voltage of the light-emitting element LD.

[0080] Referring to FIG. 4, the hole adjustment layer can include one or more of a hole injection layer HIL, a hole transport layer HTL, and an electron blocking layer EBL, which are sequentially stacked in the direction from the anode AE to the light-emitting layer. It can be understood that in some examples, one or more of the hole injection layer HIL, the hole transport layer HTL, and the electron blocking layer EBL can be provided as a multi-layer stack structure, for example, the hole transport layer HTL can include a first hole transport layer and a second hole transport layer stacked.

[0081] The electron adjustment layer can include one or more of an electron injection layer EIL, an electron transport layer ETL, and a hole blocking layer HBL, which are sequentially stacked in the direction from the cathode CE to the light-emitting layer. It can be understood that in some examples, one or more of the electron injection layer EIL, the electron transport layer ETL, and the hole blocking layer HBL can be provided as a multi-layer stack structure, for example, the electron transport layer ETL can include a first electron transport layer and a second electron transport layer stacked.

[0082] The light-emitting functional unit EFU has a multi-layered light-emitting stack structure ELS (two-layered light-emitting stack structure ELS is exemplified in FIG. 5). Referring to FIG. 5, the light-emitting element LD includes an anode AE, a multi-layered light-emitting stack structure ELS, and a cathode CE, which are sequentially stacked. Any one of the light-emitting stack structures ELS includes a hole adjusting layer, a light-emitting layer (for example, EML), and an electron adjusting layer, which are sequentially stacked. The hole adjusting layer is located on the side of the light-emitting layer close to the anode AE, and the electron adjusting layer is located on the side of the light-emitting layer close to the cathode CE.

[0083] Optionally, the light-emitting functional unit EFU can further include a charge generation layer CGL between any two adjacent light-emitting stack structures ELS to improve the efficiency of injecting electrons and holes into the two adjacent light-emitting stack structures ELS. For example, the charge generation layer CGL includes an N-type charge generation layer NCGL and a P-type charge generation layer PCGL, which are sequentially stacked between any two adjacent light-emitting stack structures ELS. The N-type charge generation layer NCGL is located adjacent to the electron adjusting layer of one of the light-emitting stack structures ELS, and is used to inject electrons into the electron adjusting layer of the light-emitting stack structure ELS. The P-type charge generation layer PCGL is located adjacent to the hole adjusting layer of the other light-emitting stack structure ELS, and is used to inject holes into the hole adjusting layer of the light-emitting stack structure ELS. In other words, the P-type charge generation layer PCGL is located on the side of the N-type charge generation layer NCGL away from the anode AE. Of course, it can be understood that the charge generation layer CGL can also include other structures in other examples.

[0084] It can be understood that in some other embodiments of the present disclosure, the electron adjusting layer of the light-emitting stack structure ELS can be omitted, or other structures in addition to the electron injection layer EIL, the electron transport layer ETL, and the hole blocking layer HBL.

[0085] It can be understood that in some other embodiments of the present disclosure, the hole adjusting layer of the light-emitting stack structure ELS can be omitted, or other structures in addition to the hole injection layer HIL, the hole transport layer HTL, and the electron blocking layer EBL.

[0086] It can be understood that when multiple light-emitting layers are provided in the light-emitting stack structure ELS, the colors of the multiple light-emitting layers can be the same or different. For example, two light-emitting layers are provided in one of the light-emitting stack structures ELS, and the two light-emitting layers can be a red light-emitting layer REML and a green light-emitting layer GEML, which are sequentially stacked. For another example, two light-emitting layers are provided in one of the light-emitting stack structures ELS, and both of the two light-emitting layers can be a red light-emitting layer REML.

[0087] In the related art, for any one light-emitting stack structure ELS, it can be provided with a light-emitting layer (for example, the light-emitting layer EML), and provided with a hole injection layer HIL, a hole transport layer HTL, an electron blocking layer EBL, a hole blocking layer HBL, an electron transport layer ETL and an electron injection layer EIL. However, the thickness of the electron blocking layer EBL needs to be less than 8 nm, and a separate chamber and a fine metal mask (FMM mask) need to be used in preparation, and the overall process is complex and the cost is high.

[0088] In the embodiments of the present disclosure, the light-emitting stack structure ELS is optimized, and the electron blocking layer EBL is optimized as an auxiliary light-emitting layer AEML having the same function. The auxiliary light-emitting layer AEML and the electron blocking layer EBL have the same function, and can share the same chamber and fine metal mask (FMM mask) with the light-emitting layer EML, thereby reducing the preparation cost and difficulty. Specifically, the light-emitting functional unit EFU includes at least one light-emitting stack structure ELS, and each light-emitting stack structure ELS includes one light-emitting unit LU; wherein the at least one light-emitting unit LU includes an auxiliary light-emitting layer AEML and a light-emitting layer EML stacked in order along the direction from the anode AE to the cathode CE; wherein the components of the auxiliary light-emitting layer AEML are part of the components of the light-emitting layer EML.

[0089] The preparation method of the auxiliary light-emitting layer AEML and the light-emitting layer EML of the light-emitting element LD based on the above structure includes the following contents:

[0090] Placing the target materials of each component required for the light-emitting layer EML in the evaporation chamber;

[0091] Shielding the target material of the component not contained in the auxiliary light-emitting layer AEML, and exposing other target materials; and evaporating the exposed target materials to form the auxiliary light-emitting layer AEML;

[0092] Exposing each target material in the same evaporation chamber, and evaporating the exposed target materials to form the light-emitting layer EML.

[0093] In the present disclosure, the auxiliary light-emitting layer AEML realizes the blocking of excitons and electrons, and the components of the auxiliary light-emitting layer AEML are part of the components of the light-emitting layer EML. In the evaporation process, the target materials of each component required for the light-emitting layer EML are placed in the evaporation chamber, the evaporation of the auxiliary light-emitting layer AEML is performed by shielding the target material of the component not contained in the auxiliary light-emitting layer AEML, and then the evaporation of the light-emitting layer EML is performed by exposing each target material in the same evaporation chamber. In the present disclosure, the auxiliary light-emitting layer AEML and the light-emitting layer EML can share the same chamber and fine metal mask (FMM mask), thereby reducing the preparation cost and process difficulty.

[0094] In the embodiments of the present disclosure, the green light emitting layer GEML includes a hole transport type host material, a thermally activated delayed fluorescence material, and a guest doped material; the green light auxiliary emitting layer GAEML includes a hole transport type host material and a guest doped material, wherein the hole transport type host material and the guest doped material in the green light auxiliary emitting layer GAEML are the same as those in the green light emitting layer GEML. For example, the green light emitting layer GEML only includes a hole transport type host material, a thermally activated delayed fluorescence material, and a guest doped material; the green light auxiliary emitting layer GAEML only includes a hole transport type host material and a guest doped material.

[0095] In the first example of the present disclosure, referring to FIG. 4, the light emitting functional unit EFU includes one light emitting stack structure ELS. For example, the display panel PNL has red light emitting elements RLD, green light emitting elements GLD, and blue light emitting elements BLD, etc. of three different colors of light emitting elements LD, and the light emitting functional unit EFU of each light emitting element LD includes one light emitting stack structure ELS. In this example, the light emitting stack structure ELS of the red light emitting element RLD includes, from the anode AE direction, a hole injection layer HIL, a hole transport layer HTL, a red light electron blocking layer REBL, a red light emitting layer REML, a hole blocking layer HBL, an electron transport layer ETL, and an electron injection layer EIL, which are sequentially stacked, wherein the red light electron blocking layer REBL and the red light emitting layer REML form a red light emitting unit LU. The light emitting stack structure ELS of the blue light emitting element BLD includes, from the anode AE direction, a hole injection layer HIL, a hole transport layer HTL, a blue light electron blocking layer BEBL, a blue light emitting layer BEML, a hole blocking layer HBL, an electron transport layer ETL, and an electron injection layer EIL, which are sequentially stacked, wherein the blue light electron blocking layer BEBL and the blue light emitting layer BEML form a blue light emitting unit LU. The light emitting stack structure ELS of the green light emitting element GLD includes, from the anode AE direction, a hole injection layer HIL, a hole transport layer HTL, a green light auxiliary emitting layer GAEML, a green light emitting layer GEML, a hole blocking layer HBL, an electron transport layer ETL, and an electron injection layer EIL, which are sequentially stacked, wherein the green light auxiliary emitting layer GAEML and the green light emitting layer GEML form a green light emitting unit LU.

[0096] In other examples, the light emitting stack structure ELS of the green light emitting element GLD can further include a green light adjusting layer GCCL between the hole transport layer HTL and the green light auxiliary emitting layer GAEML.

[0097] In other examples, the layer structure of the red light emitting element RLD can be the same as that of the green light emitting element GLD. The layer structure of the blue light emitting element BLD can be the same as that of the green light emitting element GLD.

[0098] In other embodiments of the present disclosure, one or more of the hole injection layer HIL, the hole transport layer HTL, the electron blocking layer EBL, the hole blocking layer HBL, the electron transport layer ETL, and the electron injection layer EIL can be omitted in the light-emitting stack structure ELS.

[0099] In a second example of the present disclosure, referring to FIG. 5, the light-emitting functional unit EFU includes two light-emitting stack structures ELS. For example, three different colors of light-emitting elements LD, i.e., a red light-emitting element RLD, a green light-emitting element GLD, and a blue light-emitting element BLD, are disposed on the display panel PNL; the light-emitting functional unit EFU of each light-emitting element LD includes a light-emitting stack structure ELS, a charge generation layer CGL, and a light-emitting stack structure ELS which are stacked in sequence. In this example, in the red light-emitting element RLD, the light-emitting stack structure ELS close to the anode AE includes a hole injection layer HIL, a hole transport layer HTL, a red electron blocking layer REBL, a red light-emitting layer REML, and a hole blocking layer HBL which are stacked in sequence; in other words, the electron transport layer and the electron injection layer are omitted in this light-emitting stack structure ELS. In this example, the light-emitting stack structure ELS close to the cathode CE includes a hole transport layer HTL, a red electron blocking layer REBL, a red light-emitting layer REML, a hole blocking layer HBL, an electron transport layer ETL, and an electron injection layer EIL which are stacked in sequence; in other words, the hole injection layer is omitted in this light-emitting stack structure ELS.

[0100] In this example, in the blue light-emitting element BLD, the light-emitting stack structure ELS close to the anode AE includes a hole injection layer HIL, a hole transport layer HTL, a blue electron blocking layer BEBL, a blue light-emitting layer BEML, and a hole blocking layer HBL which are stacked in sequence; in other words, the electron transport layer and the electron injection layer are omitted in this light-emitting stack structure ELS. In this example, the light-emitting stack structure ELS close to the cathode CE includes a hole transport layer HTL, a blue electron blocking layer BEBL, a blue light-emitting layer BEML, a hole blocking layer HBL, an electron transport layer ETL, and an electron injection layer EIL which are stacked in sequence; in other words, the hole injection layer is omitted in this light-emitting stack structure ELS.

[0101] In this example, the light-emitting stack ELS close to the anode AE includes, in sequence from top to bottom, a hole injection layer HIL, a hole transport layer HTL, a green light adjusting layer GCCL, a green light auxiliary emitting layer GAEML, a green light emitting layer GEML, and a hole blocking layer HBL; in other words, the light-emitting stack ELS omits an electron transport layer and an electron injection layer. In this example, the light-emitting stack ELS close to the cathode CE includes, in sequence from top to bottom, a hole transport layer HTL, a green light adjusting layer GCCL, a green light auxiliary emitting layer GAEML, a green light emitting layer GEML, a hole blocking layer HBL, an electron transport layer ETL, and an electron injection layer EIL; in other words, the light-emitting stack ELS omits a hole injection layer.

[0102] In other embodiments of the present disclosure, the film layer structures of the two light-emitting stacks ELS of the same light-emitting element LD can be the same or different.

[0103] In embodiments of the present disclosure, the anode AE can be made of a high work function electrode material. For example, the material of the anode AE can be a single material such as transparent oxide, e.g., indium tin oxide (ITO), indium zinc oxide (IZO), etc., and the thickness can be 80-200 nm, in which case the light-emitting device is a bottom emission structure. In other examples, the material of the anode AE can also be a mixed material such as silver (Ag) / indium tin oxide (ITO), aluminum (Al) / indium tin oxide (ITO), silver (Ag) / indium zinc oxide (IZO), aluminum (Al) / indium zinc oxide (IZO), etc., in which case the anode AE is a composite electrode (reflective composite electrode), the thickness of the metal layer in the composite electrode is generally 10-100 nm, and the thickness of the oxide layer is generally 5-20 nm, and the light-emitting device is a top emission structure.

[0104] In embodiments of the present disclosure, the hole injection layer HIL can be an injection material such as copper phthalocyanine (CuPc), hexaazatriphenylhexacarbonitrile (HATCN), molybdenum trioxide (MoO3), etc.; or it can be formed by P-type doping of a hole transport material, and the optional P-type dopant can be an oxide-based inorganic material or an axiophene-based organic material, and the thickness of the hole injection layer HIL can be 1-30 nm. In this example, the hole injection layer HIL can be formed by co-evaporation of multiple sources.

[0105] In the embodiments of the present disclosure, the hole transport layer HTL can be formed by a material having good hole transport properties. In this example, the material of the hole transport layer HTL can be a carbazole and its derivatives with high hole mobility. The thickness of the hole transport layer HTL is between 1-80 nm. When the hole injection layer HIL is formed by P-type doping in a hole transport material, the hole transport material in the hole injection layer HIL is the same as the material of the hole transport layer HTL.

[0106] In the embodiments of the present disclosure, the green light emitting unit LU includes a green light auxiliary emitting layer GAEML and a green light emitting layer GEML which are sequentially stacked in the direction from the anode AE to the cathode CE.

[0107] In this example, the green light emitting layer GEML includes at least three different component materials; and contains a material containing boron (B) element or / and a delayed fluorescence material. In this example, the green light emitting layer GEML at least contains a hole transport type host material, a thermally activated delayed fluorescence material (TADF), and a guest doped material. The hole transport type host material can be a carbazole material, the thermally activated delayed fluorescence material (TADF) can be a polycarbazole material with D-L-A structure, and the guest doped material can be a boron-containing organic material.

[0108] In this example, the energy value of the first triplet state energy level (T1) of the hole transport type host material of the green light emitting layer GEML is higher than the energy value of the first triplet state energy level (T1) of the thermally activated delayed fluorescence material (TADF). In this example, the difference between the energy value of the first triplet state energy level (T1) of the hole transport type host material and the energy value of the first triplet state energy level (T1) of the thermally activated delayed fluorescence material (TADF) is not less than 0.1 eV.

[0109] In the embodiments of the present disclosure, the emission spectrum range of the thermally activated delayed fluorescence material has a large overlap with the absorption spectrum range of the guest doped material. In this example, under the condition of normalized spectrum, the overlap area between the emission spectrum of the thermally activated delayed fluorescence material and the absorption spectrum of the guest doped material is not less than 60% of the absorption spectrum area of the guest doped material.

[0110] In the embodiments of the present disclosure, the green light auxiliary emitting layer GAEML contains a hole transport type host material and a guest doped material, wherein the two materials contained in the hole transport type host material and the guest doped material are the same as the materials in the green light emitting layer GEML disposed thereon. In the present disclosure, the green light auxiliary emitting layer GAEML is used to replace the green light electron blocking layer to achieve the function of blocking excitons and electrons, and the separate chamber and the fine metal mask (FMM mask) are not required during preparation, which can reduce the process difficulty and process cost.

[0111] In an embodiment of the present disclosure, the thickness of the green auxiliary light-emitting layer GAEML is less than the thickness of the green light-emitting layer GEML disposed above and connected to the green auxiliary light-emitting layer GAEML.

[0112] In an embodiment of the present disclosure, the green color conversion layer GCCL mainly functions to transport holes. In this example, the material of the green color conversion layer GCCL can be a hole-transporting carbazole, an arylamine derivative, or the like.

[0113] In an embodiment of the present disclosure, the blue light-emitting unit LU includes a blue light electron blocking layer BEBL and a blue light-emitting layer BEML, which are sequentially stacked in the direction from the anode AE to the cathode CE.

[0114] In an embodiment of the present disclosure, the blue light-emitting layer BEML contains at least one host material and one fluorescent guest material. The emission spectrum of the host material has a large overlap with the absorption spectrum of the fluorescent guest material, and under the condition of normalized spectrum, the area of the overlap between the emission spectrum of the host material and the absorption spectrum of the fluorescent guest material is not less than 60% of the area of the absorption spectrum of the guest material. In this example, the host material can be anthracene, fluorene, pyrene, and derivatives thereof, or the like. The fluorescent guest material can be a pyrene organic material or a boron-containing organic material. In this example, the doping concentration of the fluorescent guest material is 0.5-5%, and the main peak wavelength of the emission of the fluorescent guest material is between 450-480 nm.

[0115] In an embodiment of the present disclosure, the blue light electron blocking layer BEBL is mainly used to reduce the transport barrier of holes from the adjacent hole transport layer HTL to the blue light-emitting layer BEML. Therefore, the molecular highest occupied molecular orbital (HOMO) value of the material of the blue light electron blocking layer BEBL should be between the highest occupied molecular orbital (HOMO) of the adjacent hole transport layer HTL and the highest occupied molecular orbital (HOMO) of the host material of the blue light-emitting layer BEML. Meanwhile, the blue light electron blocking layer BEBL also has an exciton blocking effect, so the singlet first excited state energy S1 of the material of the blue light electron blocking layer BEBL is greater than the singlet first excited state energy S1 of the material with smaller singlet first excited state energy S1 among the host material and the guest material of the blue light-emitting layer BEML. In this example, the material of the blue light electron blocking layer BEBL can be carbazole and derivatives thereof.

[0116] In an embodiment of the present disclosure, the red light-emitting unit LU includes a red light electron blocking layer REBL and a red light-emitting layer REML, which are sequentially stacked in the direction from the anode AE to the cathode CE.

[0117] In this example, the red light emitting layer REML contains at least one P-type host material, one N-type host material, and one light emitting guest material. The N-type host material can be a common material or a thermally activated delayed fluorescence material (TADF). The light emitting guest material can be a phosphorescent material or a boron-containing fluorescent material. The thickness of the red light emitting layer REML can be 30-80 nm. The P-type host material is not particularly limited.

[0118] In this example, the red light electron blocking layer REBL is mainly used to reduce the transmission barrier of holes from the adjacent hole transport layer HTL to the red light emitting layer REML, while ensuring that the excitons of the red light emitting layer REML do not overflow. The material of the red light electron blocking layer REBL can be carbazole and its derivatives. In this example, the red light electron blocking layer EBL can also have a more subdivided layered structure, such as “R prime1 (first sub red light electron blocking layer REBL) / R prime2 (second sub red light electron blocking layer REBL)” and the like, where the absolute value of the molecular highest occupied molecular orbital energy level (HOMO) of each layer increases in turn.

[0119] In an embodiment of the present disclosure, the thickness of the hole blocking layer HBL is between 5-30 nm. The energy value of the first triplet state energy level (T1) of the material of the hole blocking layer HBL needs to be greater than the energy value of the first triplet state energy level (T1) of the thermally activated delayed fluorescence material (TADF) in the connected green light emitting layer GEML. In this example, the difference is not less than 0.2 eV. The absolute value of the HOMO of the hole blocking layer HBL material needs to be greater than the absolute value of the HOMO of the host material of all the connected light emitting layers EML (red light emitting layer REML, green light emitting layer GEML, blue light emitting layer BEML), which in this example exceeds 0.2 eV. The absolute value of the LUMO (lowest unoccupied molecular orbital) of the hole blocking layer HBL material needs to be less than the maximum value of the absolute value of the LUMO of the host material of all the connected light emitting layers EML (red light emitting layer REML, green light emitting layer GEML, blue light emitting layer BEML).

[0120] In an embodiment of the present disclosure, the charge generation layer CGL includes an N-type charge generation layer NCGL and a P-type charge generation layer PCGL arranged in layers. The N-type charge generation layer NCGL is arranged close to the anode AE.

[0121] In this example, the N-type charge generation layer NCGL can be formed by doping a low work function active metal material (such as lithium (Li), calcium (Ca), ytterbium (Yb), etc.) with an ET-type material (electron transport material).

[0122] In this example, the P-type charge generation layer PCGL can be formed by doping a P-type dopant (molybdenum oxide, etc.) into an HT-type material (hole transport material). In this case, the doping proportion of the P-type dopant in the P-type charge generation layer PCGL is higher than the doping proportion of the P-type dopant in the hole injection layer HIL, which is conducive to charge generation. In other examples, the P-type charge generation layer PCGL can also be formed by doping a P-type dopant into carbazole and its derivatives.

[0123] In an embodiment of the present disclosure, the electron transport layer ETL can be formed by evaporation of a material having good electron transport properties. In other examples, the electron transport layer ETL can also be formed by doping an electron transport material into a material such as LIQ (lithium 8-hydroxyquinoline), lithium (Li), calcium (Ca), etc. in a certain proportion.

[0124] In an embodiment of the present disclosure, the electron injection layer EIL can have a thickness of 0.5-2 nm and can be prepared using a low work function metal material. In this example, the electron injection layer EIL can be formed by evaporation of a material such as lithium (Li), calcium (Ca), ytterbium (Yb), or a metal salt such as lithium fluoride (LiF), LIQ (lithium 8-hydroxyquinoline), etc.

[0125] In an embodiment of the present disclosure, the cathode CE can be a low work function metal such as aluminum (Al), silver (Ag), magnesium (Mg), etc. In other examples, the cathode CE can also be formed by an alloy containing a low work function metal material. If the light-emitting device is a bottom-emitting device, the thickness of the cathode CE needs to be greater than 80 nm to ensure good reflectivity. If the light-emitting device is a top-emitting device, the thickness of the cathode CE can be adjusted in the range of 10-20 nm to ensure a certain transmittance.

[0126] In an embodiment of the present disclosure, referring to FIG. 6, the display panel PNL can further include an optical cover layer OC disposed on the side of the common electrode layer COML away from the substrate BP and covering the common electrode layer COML. The optical cover layer OC is used to improve optical output, and the higher the refractive index, the higher the light extraction efficiency. The optical cover layer OC can be formed by evaporation of an organic small molecule material with a thickness of 50-80 nm. In this example, the refractive index of the material of the optical cover layer OC at 460 nm should be greater than 1.8 or less than 1.5.

[0127] In an embodiment of the present disclosure, a transition layer can be disposed between the N-type charge generation layer NCGL and the hole blocking layer HBL connected thereto. In this example, the transition layer has the same function as the electron transport layer ETL, which is conducive to electron transport and improves the performance of the device. The material of the transition layer can be the same as or different from the material of the electron transport layer ETL.

[0128] In an embodiment of the present disclosure, the absolute value of the lowest unoccupied molecular orbital (LUMO) of all materials of the electron transport layer ETL is greater than the absolute value of the lowest unoccupied molecular orbital (LUMO) of all materials of the hole blocking layer HBL located below and connected to it.

[0129] In an embodiment of the present disclosure, in a top-emitting device, the red light optical cavity length can be adjusted by adjusting the thickness of the red light emitting layer EML. The blue light optical cavity length can be adjusted by adjusting the thickness of the hole transport layer HTL. The green light optical cavity length can be adjusted by adjusting the thickness of the green light emitting layer EML, and also by adjusting the thickness of the green light adjusting layer GCCL.

[0130] In an embodiment of the present disclosure, the hole transport layer HTL materials of the two adjacent light emitting stack structures ELS can be the same or different. The blue light emitting layer BEML materials of the two adjacent light emitting stack structures ELS can be the same or different. The blue light electron blocking layer BEBL materials of the two adjacent light emitting stack structures ELS can be the same or different. The green light adjusting layer GCCL materials of the two adjacent light emitting stack structures ELS can be the same or different. The green light emitting layer GEML materials of the two adjacent light emitting stack structures ELS can be the same or different. The red light electron blocking layer REBL materials of the two adjacent light emitting stack structures ELS can be the same or different. The red light emitting layer REML materials of the two adjacent light emitting stack structures ELS can be the same or different.

[0131] In an embodiment of the present disclosure, two light emitting stack structures are defined as a first light emitting stack structure ELS1 and a second light emitting stack structure ELS2. Both the first light emitting stack structure ELS1 and the second light emitting stack structure ELS2 include a hole transport layer HTL, a green light adjusting layer GCCL, a green light auxiliary emitting layer GAEML and a green light emitting layer GEML arranged in a stack. In this example, the first light emitting stack structure ELS1 is arranged close to the anode.

[0132] The absolute value of the highest occupied molecular orbital energy level of the hole transport layer HTL of the first light-emitting stack structure ELS1 is less than the absolute value of the highest occupied molecular orbital energy level of the hole transport layer HTL of the second light-emitting stack structure ELS2, and the thickness of the green light adjusting layer GCCL of the first light-emitting stack structure ELS1 is greater than the thickness of the green light adjusting layer GCCL of the second light-emitting stack structure ELS2. It can be understood that when |HOMO(HTL-1)|>|HOMO(HTL-2)|, then L1

[0133] In this example, the material of the hole transport layer HTL of the first light-emitting stack structure ELS1 is different from the material of the hole transport layer HTL of the second light-emitting stack structure ELS2, and among the two materials, the hole transport layer HTL with a higher highest occupied molecular orbital energy level has a smaller thickness of the adjacent green light adjusting layer GCCL.

[0134] In other examples, the absolute value of the highest occupied molecular orbital energy level of the hole transport layer HTL of the first light-emitting stack structure ELS1 can be greater than the absolute value of the highest occupied molecular orbital energy level of the hole transport layer HTL of the second light-emitting stack structure ELS2.

[0135] When the condition |HOMO(HTL-1)|>|HOMO(HTL-2)| is met, the hole transport layer HTL-1 has a smaller hole mobility than the hole transport layer HTL-2, at this time, reducing the thickness (L1) of the green light adjusting layer GCCL-1 is conducive to hole transport and improves the device efficiency, and vice versa.

[0136] In other embodiments of the present disclosure, the light-emitting functional unit EFU can include three, four, five, or the like, of the light-emitting stack structures ELS stacked.

[0137] In other embodiments of the present disclosure, the stacking positions of the first light-emitting stack structure ELS1 and the second light-emitting stack structure ELS2 are opposite.

[0138] In a third example of the present disclosure, referring to FIG. 7, the light-emitting functional unit EFU includes two light-emitting stack structures ELS. The light-emitting functional unit EFU of the third example is different from the light-emitting functional unit EFU of the second example in that:

[0139] The two light-emitting stack structures are defined as a third light-emitting stack structure ELS3 and a fourth light-emitting stack structure ELS4. The fourth light-emitting stack structure ELS4 is disposed close to the cathode CE.

[0140] The third light-emitting stack structure ELS3 includes, in sequence from top to bottom, a hole transport layer HTL, a green light adjusting layer GCCL, a green light auxiliary emitting layer GAEML, and a green light emitting layer GEML; and the fourth light-emitting stack structure ELS4 includes, in sequence from top to bottom, a hole transport layer HTL, a green light auxiliary emitting layer GAEML, and a green light emitting layer GEML. In this example, the absolute value of the highest occupied molecular orbital energy level of the hole transport layer HTL of the third light-emitting stack structure ELS3 is smaller than the absolute value of the highest occupied molecular orbital energy level of the hole transport layer HTL of the fourth light-emitting stack structure ELS4.

[0141] For example, |HOMO(HTL-4)| > |HOMO(HTL-3)|, then L4 < L3; wherein HOMO(HTL-4) represents the molecular highest occupied molecular orbital energy level of the hole transport layer HTL in the fourth light-emitting stack structure ELS4, HOMO(HTL-3) represents the molecular highest occupied molecular orbital energy level of the hole transport layer HTL in the third light-emitting stack structure ELS3, L4 represents the thickness of the green light adjusting layer GCCL-4 in the fourth light-emitting stack structure ELS4, and L3 represents the thickness of the green light adjusting layer GCCL-3 in the third light-emitting stack structure ELS3. It can be understood that when |HOMO(HTL-4)| > |HOMO(HTL-3)|, the hole transport layer HTL-4 has a smaller hole transport rate than the hole transport layer HTL-3. In this case, reducing the thickness (L4) of the green light adjusting layer GCCL-4 is conducive to hole transport and improves the device efficiency. When L4 = 0, i.e., the green light adjusting layer GCCL-4 can be absent, in this case, since the absolute value of the molecular highest occupied molecular orbital energy level HOMO of the hole transport layer HTL-4 is large, the potential barrier with the green light auxiliary emitting layer GAEML-4 is small, and the hole transport is not affected, i.e., the device performance is almost not affected, and at the same time, one more cavity and one FMM mask can be reduced, further reducing the process difficulty and preparation cost.

[0142] In a fourth example of the present disclosure, the light-emitting functional unit EFU includes two light-emitting stack structures ELS. The light-emitting functional unit EFU of the fourth example is different from the light-emitting functional unit EFU of the second example in that:

[0143] The two light-emitting stack structures are defined as a fifth light-emitting stack structure ELS5 and a sixth light-emitting stack structure ELS6. The sixth light-emitting stack structure ELS6 is disposed close to the cathode CE.

[0144] The absolute value of the difference between the highest occupied molecular orbital energy level of the hole transport layer HTL and the highest occupied molecular orbital energy level of the hole transport type host material in the light-emitting layer EML is not less than 0.25 eV. The materials of the hole transport layers HTL in the two adjacent light-emitting stack structures ELS are the same. It can be understood that the materials of the hole transport layers HTL in the fifth light-emitting stack structure ELS5 and the sixth light-emitting stack structure ELS6 are the same. The sum of the thicknesses of the hole transport layer HTL and the green light adjustment layer GCCL in the fifth light-emitting stack structure ELS5 is greater than the sum of the thicknesses of the hole transport layer HTL and the green light adjustment layer GCCL in the sixth light-emitting stack structure ELS6. It can be understood that when |HOMO(HTL)-HOMO(Host)|≥0.25 eV, then THK(HTL-5)+L1>THK(HTL-6)+L2, where HOMO(HTL) represents the molecular highest occupied molecular orbital energy level of the hole transport layer HTL, HOMO(Host) represents the molecular highest occupied molecular orbital energy level of the hole transport type host material in the green light-emitting unit LU, THK(HTL-5) represents the thickness of the hole transport layer HTL-5 in the fifth light-emitting stack structure ELS5, THK(HTL-6) represents the thickness of the hole transport layer HTL-6 in the sixth light-emitting stack structure ELS6, L5 represents the thickness of the green light adjustment layer GCCL-5 in the fifth light-emitting stack structure ELS5, and L6 represents the thickness of the green light adjustment layer GCCL-6 in the sixth light-emitting stack structure ELS6. In this example, since there is an energy barrier between the hole transport layer HTL and the green light-emitting unit, that is, the absolute value of the difference ΔHOMO between the molecular highest occupied molecular orbital energy level HOMO of the hole transport layer HTL and the molecular highest occupied molecular orbital energy level HOMO of the hole transport type host material in the green light-emitting unit is not less than 0.25 eV, at this time, L5 and L6 cannot be =0, that is, the green light adjustment layer GCCL-6 and the green light adjustment layer GCCL-5 both exist. The thickness of the hole transport layer HTL-5 and the thickness of the green light adjustment layer GCCL-5 are greater than the thickness of the hole transport layer HTL-6 and the thickness of the green light adjustment layer GCCL-6, at this time, which is beneficial to hole injection and hole transport, increases the current density in the green light-emitting unit, and improves the light-emitting efficiency.

[0145] In a fifth example of the present disclosure, the light-emitting functional unit EFU includes two light-emitting stack structures ELS. The light-emitting functional unit EFU of the fifth example is different from the light-emitting functional unit EFU of the fourth example in that:

[0146] The two light-emitting stack structures are defined as a seventh light-emitting stack structure ELS7 and an eighth light-emitting stack structure ELS8. The eighth light-emitting stack structure ELS8 is disposed close to the cathode CE.

[0147] The absolute value of the difference between the highest occupied molecular orbital energy level of the hole transport layer HTL and the highest occupied molecular orbital energy level of the hole transport type host material in the light-emitting layer EML is not less than 0.25 eV. The materials of the hole transport layers HTL in the adjacent two light-emitting stack structures ELS are the same. It can be understood that the materials of the hole transport layers HTL in the seventh light-emitting stack structure ELS7 and the eighth light-emitting stack structure ELS8 are the same.

[0148] The thickness of the hole transport layer HTL of the seventh light-emitting stack structure ELS7 is large, and the thickness of the green light adjustment layer GCCL is small. In other words, if the thickness of the hole transport layer HTL in the seventh light-emitting stack structure ELS7 is large, then the thickness of the green light adjustment layer GCCL in the seventh light-emitting stack structure ELS7 is small; conversely, if the thickness of the hole transport layer HTL in the eighth light-emitting stack structure ELS8 is large, then the thickness of the green light adjustment layer GCCL in the eighth light-emitting stack structure ELS8 is small. It can be understood that when |HOMO(HTL)-HOMO(Host)|≥0.25 eV, THK(HTL-7)>THK(HTL-8), L7

[0149] In the present disclosure, the hole injection and hole transport capability are adjusted by thickness to match the hole transport requirements at different positions of the series structure, and the highest efficiency of the two light emitting positions is achieved.

[0150] The present disclosure adopts the adjustment layer CCL and the auxiliary light emitting layer AEML to cooperate, replaces the electron blocking layer EBL structure in the related art, and adopts the design scheme of the hole transport layer HTL, so that the device performance is good, the number of evaporation chambers and FMM masks is reduced, and the manufacturing process difficulty and cost are reduced.

[0151] The present disclosure takes the structure of FIG. 6 as an example, gives multiple embodiments (taking a green light emitting unit LU as an example) using the structure in the related art and using the structure in the present disclosure, performs a comparative experiment, and explains and describes the performance of the stacked light emitting device.

[0152] Related art embodiments:

[0153] The anode is a mixed material of silver (Ag) and indium tin oxide (ITO), wherein the thickness of silver (Ag) is 100 nm, and the thickness of indium tin oxide (ITO) is 8 nm; the hole injection layer is P-doped in compound A, and the doping concentration is 3%, and the total thickness of the hole injection layer is 10 nm; the material of the first hole transport layer is compound A, and the thickness is The material of the first green light adjustment layer is compound D, and the thickness is The thickness of the first green light blocking layer is 5 nm; the hole type host material of the first green light emitting layer is GH, the thermal activated delayed fluorescence material (TADF) is G-TADF, and the light emitting guest material is GD, and the ratio of the three is 69%:30%:1.0%; the material of the first hole blocking layer is hastelloy (HB), and the thickness is 5 nm; the material of the N-type charge generation layer is ET material doped with 1% ytterbium Yb; the material of the P-type charge generation layer is P-doped in compound A, and the doping concentration is 10%, and the thickness of the P-type charge generation layer is 10 nm; the material of the second hole transport layer is compound A, and the thickness is The material of the second green light adjustment layer is compound D; the thickness of the second green light blocking layer is 5 nm; the hole type host material of the second green light emitting layer is GH, the thermal activated delayed fluorescence material (TADF) is G-TADF, and the light emitting guest material is GD, and the ratio of the three is 69%:30%:1%; the material of the second hole blocking layer is hastelloy (HB), and the thickness is 5 nm; the material of the electron transport layer is ET material doped with LiQ at a ratio of 50%. The total thickness is 35 nm; the material of the electron injection layer is ytterbium Yb, and the thickness is 1 nm; the cathode is a magnesium silver alloy, and the thickness is 15 nm.

[0154] Based on the structure of the present application, the lower light-emitting stack structure is defined as the first light-emitting stack structure, and the upper light-emitting stack structure is defined as the second light-emitting stack structure. The following examples are given:

[0155] Example 1:

[0156] The anode AE is a mixed material of silver (Ag) and indium tin oxide (ITO), wherein the thickness of silver (Ag) is 100 nm, and the thickness of indium tin oxide (ITO) is 8 nm; the hole injection layer HIL is P-doped in compound B with a doping concentration of 3%, and the total thickness of the hole injection layer HIL is 10 nm; the material of the first hole transport layer HTL-1 is compound B, and the thickness is The material of the first green light adjustment layer GCCL-1 is compound E, and the thickness is The hole transport type host material of the first green light auxiliary emitting layer GAEML-1 is GH, and the guest doping material is GD, with a ratio of 99%:1.0%. The thickness of the first green light auxiliary emitting layer GAEML-1 is 5 nm. The hole transport type host material of the first green light emitting layer GEML-1 is GH, the thermally activated delayed fluorescence material is G-TADF, and the guest doping material is GD, with a ratio of 69%:30%:1.0%. The material of the first hole blocking layer HBL-1 is Hastelloy (HB), and the thickness is 5 nm. The material of the N-type charge generation layer NCGL is 1% Ytterbium Yb doped ET material. The material of the P-type charge generation layer PCGL is P-doped in compound C with a doping concentration of 10%, and the thickness of the P-type charge generation layer PCGL is 10 nm. The material of the second hole transport layer HTL-2 is compound C, and the thickness is The material of the second green light adjustment layer GCCL-2 is compound E, and the thickness is The hole transport type host material of the second green light auxiliary emitting layer GAEML-2 is GH, and the guest doping material is GD, with a ratio of 99%:1.0%. The thickness of the second green light auxiliary emitting layer GAEML-2 is 5 nm. The hole transport type host material of the second green light emitting layer GEML-2 is GH, the thermally activated delayed fluorescence material is G-TADF, and the guest doping material is GD, with a ratio of 69%:30%:1%. The material of the second hole blocking layer HBL-2 is Hastelloy (HB), and the thickness is 5 nm. The material of the electron transport layer ETL is 50% LiQ doped ET material, and the total thickness is 35 nm. The material of the electron injection layer EIL is Ytterbium Yb, and the thickness is 1 nm. The cathode CE is a magnesium-silver alloy, and the thickness is 15 nm.

[0157] Example 2:

[0158] The anode AE is a mixed material of silver (Ag) and indium tin oxide (ITO), wherein the thickness of silver (Ag) is 100 nm and the thickness of indium tin oxide (ITO) is 8 nm; the hole injection layer HIL is P-doped in compound C with a doping concentration of 3%, and the total thickness of the hole injection layer HIL is 10 nm; the material of the first hole transport layer HTL-1 is compound C, and the thickness is The material of the first green light adjusting layer GCCL-1 is compound E, and the thickness is The hole transport type host material of the first green light auxiliary emitting layer GAEML-1 is GH, and the guest doping material is GD, and the ratio of the two is 99%:1.0%. The thickness of the first green light auxiliary emitting layer GAEML-1 is 5 nm; the hole transport type host material of the first green light emitting layer GEML-1 is GH, the thermally activated delayed fluorescence material is G-TADF, and the guest doping material is GD, and the ratio of the three is 69%:30%:1.0%; the material of the first hole blocking layer HBL-1 is Hastelloy (HB), and the thickness is 5 nm; the material of the N-type charge generation layer NCGL is 1% Ytterbium Yb doped in ET material; the material of the P-type charge generation layer PCGL is P-doped in compound B with a doping concentration of 10%, and the thickness of the P-type charge generation layer PCGL is 10 nm; the material of the second hole transport layer HTL-2 is compound B, and the thickness is The material of the second green light adjusting layer GCCL-2 is compound E, and the thickness is The hole transport type host material of the second green light auxiliary emitting layer GAEML-2 is GH, and the guest doping material is GD, and the ratio of the two is 99%:1.0%. The thickness of the second green light auxiliary emitting layer GAEML-2 is 5 nm; the hole transport type host material of the second green light emitting layer GEML-2 is GH, the thermally activated delayed fluorescence material is G-TADF, and the guest doping material is GD, and the ratio of the three is 69%:30%:1. The material of the second hole blocking layer HBL-2 is Hastelloy (HB), and the thickness is 5 nm; the material of the electron transport layer ETL is 50% LiQ doped in ET material, and the total thickness is 35 nm; the material of the electron injection layer EIL is Ytterbium Yb, and the thickness is 1 nm; and the cathode CE is a magnesium-silver alloy with a thickness of 15 nm.

[0159] Example 3:

[0160] The anode AE is a mixed material of silver (Ag) and indium tin oxide (ITO), wherein the thickness of silver (Ag) is 100 nm and the thickness of indium tin oxide (ITO) is 8 nm; the hole injection layer HIL is P-doped in compound B with a doping concentration of 3%, and the total thickness of the hole injection layer HIL is 10 nm; the material of the first hole transport layer HTL-1 is compound B, and the thickness is The material of the first green light adjusting layer GCCL-1 is compound E, and the thickness is The hole transport type host material of the first green light auxiliary emitting layer GAEML-1 is GH, and the guest doping material is GD, and the proportion of the two is 99%:1.0%. The thickness of the first green light auxiliary emitting layer GAEML-1 is 5 nm. The hole transport type host material of the first green light emitting layer GEML-1 is GH, the thermally activated delayed fluorescence material is G-TADF, and the guest doping material is GD. The proportion of the three is 69%:30%:1.0%. The material of the first hole blocking layer HBL-1 is Hastelloy (HB), and the thickness is 5 nm. The material of the N-type charge generation layer NCGL is an ET type material doped with 1% ytterbium Yb. The material of the P-type charge generation layer PCGL is P-type doped in compound B, and the doping concentration is 10%. The thickness of the P-type charge generation layer PCGL is 10 nm. The material of the second hole transport layer HTL-2 is compound C, and the thickness is The material of the second green light adjusting layer GCCL-2 is compound E, and the thickness is The hole transport type host material of the second green light auxiliary emitting layer GAEML-2 is GH, and the guest doping material is GD, and the proportion of the two is 99%:1.0%. The thickness of the second green light auxiliary emitting layer GAEML-2 is 5 nm. The hole transport type host material of the second green light emitting layer GEML-2 is GH, the thermally activated delayed fluorescence material is G-TADF, and the guest doping material is GD. The proportion of the three is 69%:30%:1%. The material of the second hole blocking layer HBL-2 is Hastelloy (HB), and the thickness is 5 nm. The material of the electron transport layer ETL is an ET material doped with LiQ at a proportion of 50%, and the total thickness is 35 nm. The material of the electron injection layer EIL is ytterbium Yb, and the thickness is 1 nm. The cathode CE is a magnesium silver alloy, and the thickness is 15 nm.

[0161] Example 4:

[0162] The anode AE is a mixed material of silver (Ag) and indium tin oxide (ITO), wherein the thickness of silver (Ag) is 100 nm, and the thickness of indium tin oxide (ITO) is 8 nm. The hole injection layer HIL is P-type doped in compound C, and the doping concentration is 3%. The total thickness of the hole injection layer HIL is 10 nm. The material of the first hole transport layer HTL-1 is compound C, and the thickness is The material of the first green light adjusting layer GCCL-1 is compound E, and the thickness is The hole transport type host material of the first green auxiliary light emitting layer GAEML-1 is GH, and the guest dopant material is GD, with a ratio of 99%:1.0%, and the thickness of the first green auxiliary light emitting layer GAEML-1 is 5 nm; the hole transport type host material of the first green light emitting layer GEML-1 is GH, the thermal activated delayed fluorescence material is G-TADF, and the guest dopant material is GD, with a ratio of 69%:30%:1.0%; the material of the first hole blocking layer HBL-1 is Hastelloy (HB), and the thickness is 5 nm; the material of the N-type charge generation layer NCGL is an ET type material doped with 1% ytterbium Yb; the material of the P-type charge generation layer PCGL is P-type doped in compound B, with a doping concentration of 10%, and the thickness of the P-type charge generation layer PCGL is 10 nm; the material of the second hole transport layer HTL-2 is compound B, and the thickness is The material of the second green light adjustment layer GCCL-2 is compound E, and the thickness is The hole transport type host material of the second green auxiliary light emitting layer GAEML-2 is GH, and the guest dopant material is GD, with a ratio of 99%:1.0%, and the thickness of the second green auxiliary light emitting layer GAEML-2 is 5 nm; the hole transport type host material of the second green light emitting layer GEML-2 is GH, the thermal activated delayed fluorescence material is G-TADF, and the guest dopant material is GD, with a ratio of 69%:30%:1%; the material of the second hole blocking layer HBL-2 is Hastelloy (HB), and the thickness is 5 nm; the material of the electron transport layer ETL is an ET material doped with LiQ at a ratio of 50%, and the total thickness is 35 nm; the material of the electron injection layer EIL is ytterbium Yb, and the thickness is 1 nm; and the cathode CE is a magnesium silver alloy, and the thickness is 15 nm.

[0163] Example 5:

[0164] The anode AE is a mixed material of silver (Ag) and indium tin oxide (ITO), wherein the thickness of silver (Ag) is 100 nm, and the thickness of indium tin oxide (ITO) is 8 nm; the hole injection layer HIL is P-type doped in compound C, with a doping concentration of 3%, and the total thickness of the hole injection layer HIL is 10 nm; the material of the first hole transport layer HTL-1 is compound C, and the thickness is The material of the first green light adjustment layer GCCL-1 is compound E, and the thickness is The hole transport type host material of the first green auxiliary light emitting layer GAEML-1 is GH, and the guest dopant material is GD, with a ratio of 99%:1.0%, and the thickness of the first green auxiliary light emitting layer GAEML-1 is 5 nm; the hole transport type host material of the first green light emitting layer GEML-1 is GH, the thermal activated delayed fluorescence material is G-TADF, and the guest dopant material is GD, with a ratio of 69%:30%:1.0%; the material of the first hole blocking layer HBL-1 is Hastelloy (HB), and the thickness is 5 nm; the material of the N-type charge generation layer NCGL is an ET type material doped with 1% ytterbium Yb; the material of the P-type charge generation layer PCGL is P-type doped in compound C, with a doping concentration of 10%, and the thickness of the P-type charge generation layer PCGL is 10 nm; the material of the second hole transport layer HTL-2 is compound C, and the thickness is The material of the second green light adjustment layer GCCL-2 is compound E, and the thickness is The hole transport type host material of the second green auxiliary light emitting layer GAEML-2 is GH, and the guest dopant material is GD, with a ratio of 99%:1.0%, and the thickness of the second green auxiliary light emitting layer GAEML-2 is 5 nm; the hole transport type host material of the second green light emitting layer GEML-2 is GH, the thermal activated delayed fluorescence material is G-TADF, and the guest dopant material is GD, with a ratio of 69%:30%:1%; the material of the second hole blocking layer HBL-2 is Hastelloy (HB), and the thickness is 5 nm; the material of the electron transport layer ETL is an ET material doped with LiQ at a ratio of 50%, and the total thickness is 35 nm; the material of the electron injection layer EIL is ytterbium Yb, and the thickness is 1 nm; and the cathode CE is a magnesium silver alloy, and the thickness is 15 nm.

[0165] Example 6:

[0166] The anode AE is a mixed material of silver (Ag) and indium tin oxide (ITO), wherein the thickness of silver (Ag) is 100 nm, and the thickness of indium tin oxide (ITO) is 8 nm; the hole injection layer HIL is P-type doped in compound C, with a doping concentration of 3%, and the total thickness of the hole injection layer HIL is 10 nm; the material of the first hole transport layer HTL-1 is compound C, and the thickness is The material of the first green light adjustment layer GCCL-1 is compound E, and the thickness is The hole transport type host material of the first green auxiliary light emitting layer GAEML-1 is GH, and the guest dopant material is GD, with a ratio of 99%:1.0%, and the thickness of the first green auxiliary light emitting layer GAEML-1 is 5 nm; the hole transport type host material of the first green light emitting layer GEML-1 is GH, the thermal activated delayed fluorescence material is G-TADF, and the guest dopant material is GD, with a ratio of 69%:30%:1.0%; the material of the first hole blocking layer HBL-1 is Hastelloy (HB), and the thickness is 5 nm; the material of the N-type charge generation layer NCGL is an ET type material doped with 1% ytterbium Yb; the material of the P-type charge generation layer PCGL is P-type doped in compound C, with a doping concentration of 10%, and the thickness of the P-type charge generation layer PCGL is 10 nm; the material of the second hole transport layer HTL-2 is compound C, and the thickness is The material of the second green light adjustment layer GCCL-2 is compound E, and the thickness is The hole transport type host material of the second green auxiliary light emitting layer GAEML-2 is GH, and the guest dopant material is GD, with a ratio of 99%:1.0%, and the thickness of the second green auxiliary light emitting layer GAEML-2 is 5 nm; the hole transport type host material of the second green light emitting layer GEML-2 is GH, the thermal activated delayed fluorescence material is G-TADF, and the guest dopant material is GD, with a ratio of 69%:30%:1%. The material of the second hole blocking layer HBL-2 is Hastelloy (HB), and the thickness is 5 nm; the material of the electron transport layer ETL is an ET material doped with LiQ at a ratio of 50%, and the total thickness is 35 nm; the material of the electron injection layer EIL is ytterbium Yb, and the thickness is 1 nm; and the cathode CE is a magnesium silver alloy, and the thickness is 15 nm.

[0167] Example 7:

[0168] The anode AE is a mixed material of silver (Ag) and indium tin oxide (ITO), wherein the thickness of silver (Ag) is 100 nm, and the thickness of indium tin oxide (ITO) is 8 nm; the hole injection layer HIL is P-type doped in compound C, with a doping concentration of 3%, and the total thickness of the hole injection layer HIL is 10 nm; the material of the first hole transport layer HTL-1 is compound C, and the thickness is The material of the first green light adjustment layer GCCL-1 is compound E, and the thickness is The hole transport type host material of the first green auxiliary light emitting layer GAEML-1 is GH, and the guest dopant material is GD, with a ratio of 99%:1.0%, and the thickness of the first green auxiliary light emitting layer GAEML-1 is 5 nm; the hole transport type host material of the first green light emitting layer GEML-1 is GH, the thermal activated delayed fluorescence material is G-TADF, and the guest dopant material is GD, with a ratio of 69%:30%:1.0%; the material of the first hole blocking layer HBL-1 is Hastelloy (HB), and the thickness is 5 nm; the material of the N-type charge generation layer NCGL is an ET type material doped with 1% ytterbium Yb; the material of the P-type charge generation layer PCGL is P-type doped in compound C, with a doping concentration of 10%, and the thickness of the P-type charge generation layer PCGL is 10 nm; the material of the second hole transport layer HTL-2 is compound C, and the thickness is The material of the second green light adjustment layer GCCL-2 is compound E, and the thickness is The hole transport type host material of the second green auxiliary light emitting layer GAEML-2 is GH, and the guest dopant material is GD, with a ratio of 99%:1.0%, and the thickness of the second green auxiliary light emitting layer GAEML-2 is 5 nm; the hole transport type host material of the second green light emitting layer GEML-2 is GH, the thermal activated delayed fluorescence material is G-TADF, and the guest dopant material is GD, with a ratio of 69%:30%:1%; the material of the second hole blocking layer HBL-2 is Hastelloy (HB), and the thickness is 5 nm; the material of the electron transport layer ETL is an ET material doped with LiQ at a ratio of 50%, and the total thickness is 35 nm; the material of the electron injection layer EIL is ytterbium Yb, and the thickness is 1 nm; and the cathode CE is a magnesium silver alloy, and the thickness is 15 nm.

[0169] Example 8:

[0170] The anode AE is a mixed material of silver (Ag) and indium tin oxide (ITO), wherein the thickness of silver (Ag) is 100 nm, and the thickness of indium tin oxide (ITO) is 8 nm; the hole injection layer HIL is P-type doped in compound B, with a doping concentration of 3%, and the total thickness of the hole injection layer HIL is 10 nm; the material of the first hole transport layer HTL-1 is compound B, and the thickness is The material of the first green light adjustment layer GCCL-1 is compound E, and the thickness is The hole transport type host material of the first green auxiliary light emitting layer GAEML-1 is GH, and the guest dopant material is GD, with a ratio of 99%:1.0%, and the thickness of the first green auxiliary light emitting layer GAEML-1 is 5 nm; the hole transport type host material of the first green light emitting layer GEML-1 is GH, the thermal activated delayed fluorescence material is G-TADF, and the guest dopant material is GD, with a ratio of 69%:30%:1.0%; the material of the first hole blocking layer HBL-1 is Hastelloy (HB), and the thickness is 5 nm; the material of the N-type charge generation layer NCGL is an ET type material doped with 1% ytterbium Yb; the material of the P-type charge generation layer PCGL is P-type doped in compound B, with a doping concentration of 10%, and the thickness of the P-type charge generation layer PCGL is 10 nm; the material of the second hole transport layer HTL-2 is compound B, and the thickness is The material of the second green light adjustment layer GCCL-2 is compound E, and the thickness is The hole transport type host material of the second green auxiliary light emitting layer GAEML-2 is GH, and the guest dopant material is GD, with a ratio of 99%:1.0%, and the thickness of the second green auxiliary light emitting layer GAEML-2 is 5 nm; the hole transport type host material of the second green light emitting layer GEML-2 is GH, the thermal activated delayed fluorescence material is G-TADF, and the guest dopant material is GD, with a ratio of 69%:30%:1%; the material of the second hole blocking layer HBL-2 is Hastelloy (HB), and the thickness is 5 nm; the material of the electron transport layer ETL is an ET material doped with LiQ at a ratio of 50%, and the total thickness is 35 nm; the material of the electron injection layer EIL is ytterbium Yb, and the thickness is 1 nm; and the cathode CE is a magnesium silver alloy, and the thickness is 15 nm.

[0171] Example 9:

[0172] The anode AE is a mixed material of silver (Ag) and indium tin oxide (ITO), wherein the thickness of silver (Ag) is 100 nm, and the thickness of indium tin oxide (ITO) is 8 nm; the hole injection layer HIL is P-type doped in compound B, with a doping concentration of 3%, and the total thickness of the hole injection layer HIL is 10 nm; the material of the first hole transport layer HTL-1 is compound B, and the thickness is The material of the first green light adjustment layer GCCL-1 is compound E, and the thickness is The hole transport type host material of the first green auxiliary light emitting layer GAEML-1 is GH, and the guest dopant material is GD, with a ratio of 99%:1.0%, and the thickness of the first green auxiliary light emitting layer GAEML-1 is 5 nm; the hole transport type host material of the first green light emitting layer GEML-1 is GH, the thermal activated delayed fluorescence material is G-TADF, and the guest dopant material is GD, with a ratio of 69%:30%:1.0%; the material of the first hole blocking layer HBL-1 is Hastelloy (HB), and the thickness is 5 nm; the material of the N-type charge generation layer NCGL is an ET type material doped with 1% ytterbium Yb; the material of the P-type charge generation layer PCGL is P-type doped in compound B, with a doping concentration of 10%, and the thickness of the P-type charge generation layer PCGL is 10 nm; the material of the second hole transport layer HTL-2 is compound B, and the thickness is The material of the second green light adjustment layer GCCL-2 is compound E, and the thickness is The hole transport type host material of the second green auxiliary light emitting layer GAEML-2 is GH, and the guest dopant material is GD, with a ratio of 99%:1.0%, and the thickness of the second green auxiliary light emitting layer GAEML-2 is 5 nm; the hole transport type host material of the second green light emitting layer GEML-2 is GH, the thermal activated delayed fluorescence material is G-TADF, and the guest dopant material is GD, with a ratio of 69%:30%:1%; the material of the second hole blocking layer HBL-2 is Hastelloy (HB), and the thickness is 5 nm; the material of the electron transport layer ETL is an ET material doped with LiQ at a ratio of 50%, and the total thickness is 35 nm; the material of the electron injection layer EIL is ytterbium Yb, and the thickness is 1 nm; and the cathode CE is a magnesium silver alloy, and the thickness is 15 nm.

[0173] Example 10:

[0174] The anode AE is a mixed material of silver (Ag) and indium tin oxide (ITO), wherein the thickness of silver (Ag) is 100 nm, and the thickness of indium tin oxide (ITO) is 8 nm; the hole injection layer HIL is P-type doped in compound B, with a doping concentration of 3%, and the total thickness of the hole injection layer HIL is 10 nm; the material of the first hole transport layer HTL-1 is compound B, and the thickness is The material of the first green light adjustment layer GCCL-1 is compound E, and the thickness is The hole transport type host material of the first green light auxiliary light emitting layer GAEML-1 is GH, the guest dopant material is GD, and the ratio of the two is 99%:1.0%, and the thickness of the first green light auxiliary light emitting layer GAEML-1 is 5 nm; the hole transport type host material of the first green light emitting layer GEML-1 is GH (GH alloy is a kind of metal material, which belongs to a kind of nickel-based alloy), the thermally activated delayed fluorescence material is G-TADF, and the guest dopant material is GD, and the ratio of the three is 69%:30%:1.0%; the material of the first hole blocking layer HBL-1 is hastelloy (HB), and the thickness is 5 nm; the material of the N-type charge generation layer NCGL is ET type material doped with 1% ytterbium Yb; the material of the P-type charge generation layer PCGL is P-type doped in compound B, and the doping concentration is 10%, and the thickness of the P-type charge generation layer PCGL is 10 nm; the material of the second hole transport layer HTL-2 is compound B, and the thickness is The material of the second green light adjusting layer GCCL-2 is compound E, and the thickness is The hole transport type host material of the second green light auxiliary light emitting layer GAEML-2 is GH, the guest dopant material is GD, and the ratio of the two is 99%:1.0%, and the thickness of the second green light auxiliary light emitting layer GAEML-2 is 5 nm; the hole transport type host material of the second green light emitting layer GEML-2 is GH, the thermally activated delayed fluorescence material is G-TADF, and the guest dopant material is GD, and the ratio of the three is 69%:30%:1%. The material of the second hole blocking layer HBL-2 is hastelloy (HB), and the thickness is 5 nm; the material of the electron transport layer ETL is ET material doped with LiQ at a ratio of 50%, and the total thickness is 35 nm; the material of the electron injection layer EIL is ytterbium Yb, and the thickness is 1 nm; and the cathode CE is magnesium silver alloy, and the thickness is 15 nm.

[0175] In the above examples, the parameters of the related materials are as follows:

[0176] Table 1 relates to the energy level, excited state energy and mobility of the material

[0177] Referring to Table 1, the HOMO of compound A is -5.45, the LUMO is -2.45, and the hole mobility is 3.11*10 -5 and so on.

[0178] The device performance parameters of the above examples are as follows:

[0179] Table 2: Device performance of examples 1-4

[0180] Table 3: Device performance of examples 5-10

[0181] In the above examples, compound A, compound B, compound C, compound D, and compound E can be carbazole and derivatives thereof.

[0182] Based on the above examples, the related art examples adopt a conventional scheme, and the green light adjusting layer GCCL and the green light electron blocking layer EBL each need a separate chamber and FMM Mask, and the thickness of the green light electron blocking layer EBL is only 5 nm, and the film thickness is not easy to accurately control.

[0183] Examples 1-4 are examples that adopt the scheme in the present disclosure, and the device efficiency and lifetime are improved to different degrees, for example, the voltage is 100%, the device efficiency is 100%, and the LT95 lifetime is 100%. In Example 1, which adopts the scheme in the present disclosure, the voltage is 101%, the device efficiency is 109%, and the LT95 lifetime is 104%, and so on. GH:GD is used as the green light auxiliary light-emitting layer GAEML to replace the green light electron blocking layer EBL, reducing the use of one material, reducing one chamber and one FMM mask. At the same time, in different light-emitting regions, the hole transport layer HTL uses different materials, and the light-emitting unit LU using the hole transport layer HTL with a deep HOMO material (i.e., a large absolute value of HOMO) can further reduce the use of the green light adjusting layer GCCL material, further reduce the chamber and FMM Mask, and achieve the advantage of cost reduction. The efficiency of Example 1 and Example 2 is better than that of Example 3 and Example 4, which is because the mobility of the hole transport layer HTL with a deep HOMO material is generally low, and when the film thickness is thick or the interface potential barrier is large, it affects the hole injection and transport, resulting in an increase in voltage, a decrease in current density in the light-emitting layer EML, and thus a decrease in efficiency. However, due to the reduction in exciton density, the lifetime is increased to a certain extent.

[0184] Embodiments 5-10 are devices using the schemes in the present disclosure, which have different degrees of improvement in device efficiency and lifetime. GH:GD is used as green auxiliary light-emitting layer GAEML to replace the green electron blocking layer EBL, reducing the use of one material, one chamber and one FMM mask. At the same time, according to the characteristics of different light-emitting regions, different film thickness schemes of hole transport layer HTL and adjustment layer CCL are used to control hole injection and hole transport, so as to maximize the utilization rate of excitons and improve the device performance. Among them, compounds C are used as hole transport layer HTL materials in embodiments 5-7, and compounds B are used as hole transport layer HTL materials in embodiments 8-10. Compared with the latter, the former has a larger HOMO difference with the HOST (host) material in the light-emitting layer EML, and forms a stepped barrier interface with the adjustment layer CCL material, which is more conducive to the interface hole injection and transport. The latter has some potential barriers at the interface, which leads to an increase in voltage and a slight loss of efficiency, but it will increase the lifetime to some extent.

[0185] In summary, by optimizing the combination of hole transport layer HTL and adjustment layer CCL at different positions of specific light-emitting regions, adjusting the hole injection and hole transport capacity, matching the hole transport requirements at different positions of the series structure, the highest efficiency of the two light-emitting positions is realized.

[0186] Other embodiments of the present disclosure will be apparent to those skilled in the art from consideration of the specification and practice of the application disclosed herein. This application is intended to cover any variations, uses or adaptive changes of the present disclosure, which follow the general principles of the present disclosure and include known or customary practices in the art to which the present disclosure pertains. The specification and examples are considered to be exemplary only, and the true scope and spirit of the present disclosure are indicated by the appended claims.

Claims

1. An organic light emitting diode, characterized by, The organic light-emitting diode comprises an anode, a light-emitting functional unit and a cathode which are sequentially stacked; The light-emitting functional unit comprises at least one light-emitting stack structure, each of which comprises a light-emitting unit; wherein at least one of the light-emitting units comprises an auxiliary light-emitting layer and a light-emitting layer which are sequentially stacked in the direction from the anode to the cathode; The composition of the auxiliary light-emitting layer is part of the composition of the light-emitting layer.

2. The organic light emitting diode according to claim 1, wherein, The light-emitting functional unit comprises at least two light-emitting stack structures which are sequentially stacked.

3. The organic light-emitting diode according to claim 1, characterized in that, The light-emitting layer comprises a hole-transporting host material, a thermally activated delayed fluorescence material and a guest doped material; The auxiliary light-emitting layer comprises a hole-transporting host material and a guest doped material.

4. The organic light emitting diode of claim 2, wherein the first electrode comprises a first electrode layer and a second electrode layer, and the second electrode comprises a third electrode layer and a fourth electrode layer. The light-emitting unit further comprises an adjusting layer, and the light-emitting stack structure further comprises a hole-transporting layer located on the side of the light-emitting unit close to the anode, and the hole-transporting layer is located adjacent to the adjusting layer; The light-emitting functional unit comprises a first light-emitting stack structure and a second light-emitting stack structure which are adjacent and stacked; the first light-emitting stack structure comprises a hole-transporting layer, an adjusting layer, an auxiliary light-emitting layer and a light-emitting layer which are sequentially stacked; and the second light-emitting stack structure comprises a hole-transporting layer, an adjusting layer, an auxiliary light-emitting layer and a light-emitting layer which are sequentially stacked; The absolute value of the highest occupied molecular orbital energy level of the hole-transporting layer of the first light-emitting stack structure is smaller than the absolute value of the highest occupied molecular orbital energy level of the hole-transporting layer of the second light-emitting stack structure, and the thickness of the adjusting layer of the first light-emitting stack structure is greater than the thickness of the adjusting layer of the second light-emitting stack structure.

5. The organic light emitting diode of claim 2, wherein the first electrode comprises a first electrode layer and a second electrode layer, and the second electrode comprises a third electrode layer and a fourth electrode layer. The light-emitting stack structure further comprises a hole-transporting layer located on the side of the light-emitting unit close to the anode; The light-emitting functional unit comprises a third light-emitting stack structure and a fourth light-emitting stack structure which are adjacent and stacked; the third light-emitting stack structure comprises a hole-transporting layer, an adjusting layer, an auxiliary light-emitting layer and a light-emitting layer which are sequentially stacked; and the fourth light-emitting stack structure comprises a hole-transporting layer, an auxiliary light-emitting layer and a light-emitting layer which are sequentially stacked; The absolute value of the highest occupied molecular orbital energy level of the hole-transporting layer of the third light-emitting stack structure is smaller than the absolute value of the highest occupied molecular orbital energy level of the hole-transporting layer of the fourth light-emitting stack structure.

6. The organic light emitting diode of claim 2, wherein, The organic light-emitting diode comprises a plurality of light-emitting stack structures which are sequentially stacked; Any one of the light-emitting stack structures comprises a hole-transporting layer, an adjusting layer, an auxiliary light-emitting layer and a light-emitting layer which are sequentially stacked; the absolute value of the difference between the highest occupied molecular orbital energy level of the hole-transporting layer and the highest occupied molecular orbital energy level of the hole-transporting host material in the light-emitting layer is not less than 0.25 eV; The materials of the hole-transporting layers in two adjacent light-emitting stack structures are the same; The light-emitting functional unit comprises a fifth light-emitting stack structure and a sixth light-emitting stack structure which are adjacent and stacked; the distance between the fifth light-emitting stack structure and the anode is smaller than the distance between the sixth light-emitting stack structure and the anode; The sum of the thicknesses of the hole-transporting layer and the adjusting layer of the fifth light-emitting stack structure is greater than the sum of the thicknesses of the hole-transporting layer and the adjusting layer of the sixth light-emitting stack structure.

7. The organic light emitting diode of claim 2, wherein the first electrode comprises a first electrode layer and a second electrode layer, and the second electrode comprises a third electrode layer and a fourth electrode layer. The organic light emitting diode comprises a plurality of light emitting stack structures which are sequentially stacked; Any one of the light emitting stack structures comprises a hole transport layer, an adjusting layer, an auxiliary light emitting layer and a light emitting layer which are sequentially stacked; the absolute value of the difference between the highest occupied molecular orbital energy level of the hole transport layer and the highest occupied molecular orbital energy level of the hole transport type host material in the light emitting layer is not less than 0.25 eV; The materials of the hole transport layers in two adjacent light emitting stack structures are the same; The light emitting functional unit comprises a seventh light emitting stack structure and an eighth light emitting stack structure which are adjacent and stacked; the distance between the seventh light emitting stack structure and the anode is less than the distance between the eighth light emitting stack structure and the anode; The thickness of the hole transport layer of the seventh light emitting stack structure is large, and the thickness of the adjusting layer is small.

8. The organic light emitting diode of claim 1, wherein, The thickness of the auxiliary light emitting layer is less than the thickness of the light emitting layer.

9. The organic light emitting diode of claim 3, wherein the first electrode is a cathode electrode, and the second electrode is an anode electrode. The light emitting stack structure further comprises a hole blocking layer on the side of the light emitting unit away from the anode; The difference between the energy value of the first triplet state energy level of the hole blocking layer and the energy value of the first triplet state energy level of the thermally activated delayed fluorescence material in the light emitting layer is not less than 0.2 eV.

10. The organic light emitting diode of claim 3, wherein, The overlapping area of the emission spectrum of the thermally activated delayed fluorescence material in the light emitting layer and the absorption spectrum of the guest doped material is not less than 60% of the absorption spectrum area of the guest doped material.

11. The organic light emitting diode of claim 3, wherein the first electrode is a cathode electrode, and the second electrode is an anode electrode. The difference between the energy value of the first triplet state energy level of the hole transport type host material in the light emitting layer and the energy value of the first triplet state energy level of the thermally activated delayed fluorescence material is not less than 0.1 eV.

12. A display panel, characterized by The display panel comprises a red organic light emitting diode, a green organic light emitting diode and a blue organic light emitting diode, and the green organic light emitting diode is selected from the organic light emitting diode of any one of claims 1-11.

13. The display panel of claim 12, wherein, The display panel comprises a red organic light emitting diode, a green organic light emitting diode and a blue organic light emitting diode, and the green organic light emitting diode is selected from the organic light emitting diode of any one of claims 1-11.

14. A method of manufacturing an organic light emitting diode, characterized by, The display panel comprises a red organic light emitting diode, a green organic light emitting diode and a blue organic light emitting diode, and the green organic light emitting diode is selected from the organic light emitting diode of any one of claims 1-11. The display panel comprises a red organic light emitting diode, a green organic light emitting diode and a blue organic light emitting diode, and the green organic light emitting diode is selected from the organic light emitting diode of any one of claims 1-11. The display panel comprises a red organic light emitting diode, a green organic light emitting diode and a blue organic light emitting diode, and the green organic light emitting diode is selected from the organic light emitting diode of any one of claims 1-11. The display panel comprises a red organic light emitting diode, a green organic light emitting diode and a blue organic light emitting diode, and the green organic light emitting diode is selected from the organic light emitting diode of any one of claims 1-11. The display panel comprises a red organic light emitting diode, a green organic light emitting diode and a blue organic light emitting diode, and the green organic light emitting diode is selected from the organic light emitting diode of any one of claims 1-11.

15. The method for fabricating an organic light-emitting diode according to claim 14, characterized in that, The display panel comprises a red organic light emitting diode, a green organic light emitting diode and a blue organic light emitting diode, and the green organic light emitting diode is selected from the organic light emitting diode of any one of claims 1-11. The display panel comprises a red organic light emitting diode, a green organic light emitting diode and a blue organic light emitting diode, and the green organic light emitting diode is selected from the organic light emitting diode of any one of claims 1-11. The display panel comprises a red organic light emitting diode, a green organic light emitting diode and a blue organic light emitting diode, and the green organic light emitting diode is selected from the organic light emitting diode of any one of claims 1-11. The display panel comprises a red organic light emitting diode, a green organic light emitting diode and a blue organic light emitting diode, and the green organic light emitting diode is selected from the organic light emitting diode of any one of claims 1-11. The display panel comprises a red organic light emitting diode, a green organic light emitting diode and a blue organic light emitting diode, and the green organic light emitting diode is selected from the organic light emitting diode of any one of claims 1-11. The display panel comprises a red organic light emitting diode, a green organic light emitting diode and a blue organic light emitting diode, and the green organic light emitting diode is selected from the organic light emitting diode of any one of claims 1-11. The display panel comprises a red organic light emitting diode, a green organic light emitting diode and a blue organic light emitting diode, and the green organic light emitting diode is selected from the organic light emitting diode of any one of claims 1-11. The display panel comprises a red organic light emitting diode, a green organic light emitting diode and a blue organic light emitting diode, and the green organic light emitting diode is selected from the organic light emitting diode of any one of claims 1-11. The display panel comprises a red organic light emitting diode, a green organic light emitting diode and a blue organic light emitting diode, and the green organic light emitting diode is selected from the organic light emitting diode of any one of claims 1-11. The display panel comprises a red organic light emitting diode, a green organic light emitting diode and a blue organic light emitting diode, and the green organic light emitting diode is selected from the organic light emitting diode of any one of claims 1-11. The display panel comprises a red organic light emitting diode, a green organic light emitting diode and a blue organic light emitting diode, and the green organic light emitting diode is selected from the organic light emitting diode of any one of claims 1-11. The display panel comprises a red organic light emitting diode, a green organic light emitting diode and a blue organic light emitting diode, and the green organic light emitting diode is selected from the organic light emitting diode of any one of claims 1-11. The display panel comprises a red organic light emitting diode, a green organic light emitting diode and a blue organic light emitting diode, and the green organic light emitting diode is selected from the organic light emitting diode of any one of claims 1-11. The display panel comprises a red organic light emitting diode, a green organic light emitting diode and a blue organic light emitting diode, and the green organic light emitting diode is selected from the organic light emitting diode of any one of claims 1-11. The display panel comprises a red organic light emitting diode, a green organic light emitting diode and a blue organic light emitting diode, and the green organic light emitting diode is selected from the organic light emitting diode of any one of claims 1-11. The display panel comprises a red organic light emitting diode, a green organic light emitting diode and a blue organic light emitting diode, and the green organic light emitting diode is selected from the organic light emitting diode of any one of claims 1-11. The display panel comprises a red organic light emitting diode, a green organic light emitting diode and a blue organic light emitting diode, and the green organic light emitting diode is selected from the organic light emitting diode of any one of claims 1-11. The display panel comprises a red organic light emitting diode, a green organic light emitting diode and a blue organic light emitting diode, and the green organic light emitting diode is selected from the organic light emitting diode of any one of claims 1-11. The display panel comprises a red organic light emitting diode, a green organic light emitting diode and a blue organic light emitting diode, and the green organic light emitting diode is selected from the organic light emitting diode of any one of claims 1-11. The display panel comprises a red organic light emitting diode, a green organic light emitting diode and a blue organic light emitting diode, and the green organic light emitting diode is selected from the organic light emitting diode of any one of claims 1-11. The display panel comprises a red organic light emitting diode, a green organic light emitting diode and a blue organic light emitting diode, and the green organic light emitting diode is selected from the organic light emitting diode of any one of claims 1-11. The display panel comprises a red organic light emitting diode, a green organic light emitting diode and a blue organic light emitting diode, and the green organic light emitting diode is selected from the organic light emitting diode of any one of claims 1-11. The display panel comprises a red organic light emitting diode, a green organic light emitting diode and a blue organic light emitting diode, and the green organic light emitting diode is selected from the organic light emitting diode of any one of claims

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