CN115988897A - Display panel, preparation method thereof and display device - Google Patents

Abstract

The display panel comprises a plurality of laminated electroluminescent devices, a light emitting unit of each laminated electroluminescent device comprises at least two light emitting functional layers, a charge generation layer is arranged between every two adjacent light emitting functional layers, and the charge generation layer can separate electrons from holes and transmit the electrons to the two light emitting functional layers respectively. The host material of the charge generation layer comprises an organic material and a resistance control material, wherein the resistance control material enables the LUMO energy level of the host material of the charge generation layer to be larger than 2.8eV, the electron mobility is low due to the larger LUMO energy level, and electrons can more easily enter the LUMO energy level of the light-emitting function layer after the electrons and holes are separated. Therefore, the light-emitting device can reduce the lateral transmission of the charge generation layer, thereby improving the problem of mutual crosstalk between two adjacent light-emitting devices.

Description

Display panel, preparation method thereof and display device

Technical Field

The disclosure relates to the technical field of display, in particular to a display panel, a preparation method thereof and a display device.

Background

OLED (Organic Light Emitting Diode) display panels have been widely used in various display devices. The resolution requirement of part of the display panel is higher, and the laminated OLED can meet the process requirement.

Since the connection between the stacked layers requires a Charge Generation Layer (CGL) with relatively good conductivity, when the light emitting devices are spaced at a relatively small pitch, a lateral leakage phenomenon is likely to occur, which may cause crosstalk between the light emitting devices.

It is to be noted that the information disclosed in the above background section is only for enhancement of understanding of the background of the present disclosure, and thus may include information that does not constitute prior art known to those of ordinary skill in the art.

Disclosure of Invention

The present disclosure is directed to solving the problem that crosstalk between light emitting devices is easily caused by a phenomenon of lateral leakage when the pitch of the light emitting devices is small, and provides a display panel, a manufacturing method thereof, and a display device.

According to an aspect of the present disclosure, there is provided a display panel including a plurality of stacked electroluminescent devices including a first electrode, a second electrode, and a light emitting unit, the second electrode being disposed opposite to the first electrode; the light-emitting unit is arranged between the first electrode and the second electrode and comprises at least two light-emitting functional layers which are arranged at intervals, and a charge generation layer is arranged between every two adjacent light-emitting functional layers; the host material of the charge generation layer comprises an organic material and a resistance regulation material, and the LUMO energy level of the host material of the charge generation layer is more than 2.8eV.

In one embodiment of the present disclosure, the light emitting function layer includes a hole transport layer, an electron blocking layer, a light emitting material layer, a hole blocking layer, and an electron transport layer, which are sequentially stacked in a direction from the first electrode toward the second electrode.

In one embodiment of the present disclosure, the impedance-controlling material is the same as the electron-transporting layer.

In one embodiment of the present disclosure, the host material of the charge generation layer further includes a photosensitive material and/or a thermosensitive material.

In one embodiment of the present disclosure, the charge generation layer includes an n-type charge generation layer, the n-type charge generation layer includes a resistance control material, the n-type charge generation layer further includes a doping material, and the doping material of the n-type charge generation layer is an active metal.

In one embodiment of the present disclosure, a light emitting unit includes a first light emitting functional layer disposed adjacent to a first electrode, a second light emitting functional layer disposed adjacent to a second electrode, and a third light emitting functional layer disposed between the first light emitting functional layer and the third light emitting functional layer; the light emitting unit includes a first charge generation layer between the first light emitting function layer and the second light emitting function layer and a second charge generation layer between the second light emitting function layer and the third light emitting function layer.

In one embodiment of the present disclosure, a ratio of the lateral resistance of the second charge generation layer to the lateral resistance of the first charge generation layer is 2 or more.

In one embodiment of the present disclosure, one of the first electrode and the second electrode is a reflective electrode, and the other is a semi-transparent semi-reflective electrode.

According to another aspect of the present disclosure, there is provided a method of manufacturing a display panel, including manufacturing a plurality of stacked electroluminescent devices, the manufacturing of the stacked electroluminescent devices including: forming a first electrode; forming a light emitting unit on one side of the first electrode, including: forming at least two light-emitting functional layers, forming a charge generation layer between every two adjacent light-emitting functional layers, wherein the host material of the charge generation layer comprises an organic material and an impedance control material, and the LUMO energy level of the host material of the charge generation layer is more than 2.8eV; and forming a second electrode on the side of the light-emitting unit far away from the first electrode.

In one embodiment of the present disclosure, the charge generation layer further includes a doping material, and the organic material, the impedance adjusting material, and the doping material of the charge generation layer are formed on the light emitting function layer by a triple-source co-evaporation method.

In one embodiment of the present disclosure, the host material of the charge generation layer further includes a photosensitive material and/or a thermosensitive material, and the method further includes: and shielding the light-emitting functional layer of each laminated electroluminescent device through a mask plate, and carrying out photoetching or thermal etching on the periphery of the light-emitting functional layer of each laminated electroluminescent device.

According to still another aspect of the present disclosure, there is provided a display device including the display panel according to one aspect of the present disclosure.

The display panel comprises a plurality of laminated electroluminescent devices, wherein the light emitting unit of each laminated electroluminescent device comprises at least two light emitting functional layers, a charge generation layer is arranged between every two adjacent light emitting functional layers, and the charge generation layer can separate electrons from holes and respectively transmit the electrons to the two light emitting functional layers. The main material of the charge generation layer comprises an organic material and an impedance adjusting and controlling material, wherein the impedance adjusting and controlling material enables the LUMO energy level of the main material of the charge generation layer to be larger than 2.8eV, the electron mobility to be lower due to the larger LUMO energy level, and electrons can more easily enter the LUMO energy level of the light-emitting function layer after the electrons and holes are separated. Therefore, the light emitting device can reduce the lateral transmission of the charge generation layer, thereby improving the problem of mutual crosstalk between two adjacent light emitting devices.

It is to be understood that both the foregoing general description and the following detailed description are exemplary and explanatory only and are not restrictive of the disclosure.

Drawings

The accompanying drawings, which are incorporated in and constitute a part of this specification, illustrate embodiments consistent with the present disclosure and together with the description, serve to explain the principles of the disclosure. It is to be understood that the drawings in the following description are merely exemplary of the disclosure, and that other drawings may be derived from those drawings by one of ordinary skill in the art without the exercise of inventive faculty.

Fig. 1 is a schematic cross-sectional view of a pixel layer of a display panel according to an embodiment of the disclosure.

Fig. 2 is a schematic cross-sectional view of a light emitting device according to an embodiment of the present disclosure.

Fig. 3 is a schematic diagram of a conventional charge generation layer.

Fig. 4 is a schematic diagram of a charge generation layer according to an embodiment of the present disclosure.

Fig. 5 is a schematic cross-sectional view of a display panel according to an embodiment of the disclosure.

Fig. 6 is a schematic cross-sectional view of another display panel according to an embodiment of the present disclosure.

In the figure: 1-driving backplane, 10-substrate base plate, 11-transistor, 111-gate, 112-active layer, 113-first pole, 114-second pole, 115-gate insulating layer, 12-first transistor, 13-second transistor, 14-contact hole, 15-insulating layer, 151-interlayer dielectric layer, 152-protective layer, 153-planarization layer, 16-third conductive layer, 18-buffer layer, 100-driving circuit layer, 2-light emitting layer, 21-first conductive layer, 22-light emitting unit layer, 23-second conductive layer, 220-light emitting device, 2201-first light emitting device, 2202-second light emitting device, 2203-third light emitting device, 221-first electrode, 222-second electrode, 223-a light-emitting unit, 224-a first light-emitting functional layer, 225-a second light-emitting functional layer, 226-a third light-emitting functional layer, 227-a first charge generation layer, 2271-a p-type charge generation layer, 2272-an n-type charge generation layer, 228-a second charge generation layer, 229-a carrier injection layer, 201-a hole transport layer, 202-an electron blocking layer, 203-a light-emitting material layer, 204-a hole blocking layer, 205-an electron transport layer, 3-a color film layer, 31-a black matrix, 32-a light filtering unit, 33-a package substrate, 4-a package layer group, 41-a first inorganic package layer, 42-an organic package layer, 43-a second inorganic package layer.

Detailed Description

Example embodiments will now be described more fully with reference to the accompanying drawings. Example embodiments may, however, be embodied in many different forms and should not be construed as limited to the embodiments set forth herein; rather, these embodiments are provided so that this disclosure will be thorough and complete, and will fully convey the concept of example embodiments to those skilled in the art. The same reference numerals in the drawings denote the same or similar structures, and thus their detailed description will be omitted. Furthermore, the drawings are merely schematic illustrations of the present disclosure and are not necessarily drawn to scale.

Although relative terms, such as "upper" and "lower," may be used in this specification to describe one element of an icon relative to another, these terms are used in this specification for convenience only, e.g., in accordance with the orientation of the examples described in the figures. It will be appreciated that if the device of the icon were turned upside down, the element described as "upper" would become the element "lower". When a structure is "on" another structure, it may mean that the structure is integrally formed with the other structure, or that the structure is "directly" disposed on the other structure, or that the structure is "indirectly" disposed on the other structure via another structure.

The terms "a", "an", "the", "said" and "at least one" are used to indicate the presence of one or more elements/components/parts/etc.; the terms "comprising" and "having" are intended to be inclusive and mean that there may be additional elements/components/etc. other than the listed elements/components/etc.; the terms "first," "second," and "third," etc. are used merely as labels, and are not limiting on the number of their objects.

The disclosed embodiments provide a display panel. As shown in fig. 1 to 6, the display panel includes a plurality of stacked electroluminescent devices 220, the stacked electroluminescent devices 220 including a first electrode 221, a second electrode 222, and a light emitting unit 223, the second electrode 222 being disposed opposite to the first electrode 221; the light emitting unit 223 is disposed between the first electrode 221 and the second electrode 222, the light emitting unit 223 includes at least two light emitting functional layers, the at least two light emitting functional layers are disposed at intervals, and a charge generation layer is disposed between each two adjacent light emitting functional layers; the host material of the charge generation layer comprises an organic material and a resistance regulation material, and the LUMO energy level of the host material of the charge generation layer is more than 2.8eV.

And a charge generation layer is arranged between every two adjacent light-emitting functional layers, is a connecting layer of the two light-emitting functional layers, and can separate electrons from holes and respectively transmit the electrons to the two light-emitting functional layers. The host material of the charge generation layer comprises an organic material and a resistance control material, wherein the resistance control material enables the LUMO energy level of the host material of the charge generation layer to be larger than 2.8eV, the electron mobility is low due to the larger LUMO energy level, and electrons can more easily enter the LUMO energy level of the light-emitting function layer after the electrons and holes are separated. Thus, the light emitting device 220 can reduce the lateral transport of the charge generation layer, thereby improving the problem of mutual crosstalk between two adjacent light emitting devices 220.

Fig. 1 shows a schematic diagram of a display panel provided by the present disclosure. As shown in fig. 1, the display panel includes a pixel layer, the pixel layer may include a light emitting layer 2 and a color film layer 3, the light emitting layer 2 may include a plurality of light emitting devices 220, the plurality of light emitting devices 220 in fig. 1 are a first light emitting device 2201, a second light emitting device 2202 and a third light emitting device 2203, respectively, for example, the first light emitting device 2201, the second light emitting device 2202 and the third light emitting device 2203 are respectively located in different sub-pixels, thereby constituting a pixel unit PX, the pixel unit PX may emit full color light in combination with the color film layer 3, the color film layer 3 includes sub-filter units 32 of three different colors, and the sub-filter units 32 of three different colors are a red sub-filter unit, a green sub-filter unit and a blue sub-filter unit, respectively.

As shown in fig. 2, the light emitting device 220 includes a first electrode 221, a second electrode 222, and a light emitting unit 223, the second electrode 222 being disposed opposite to the first electrode 221; the light emitting unit 223 is disposed between the first electrode 221 and the second electrode 222, the light emitting unit 223 includes a first light emitting function layer 224, a second light emitting function layer 225, and a third light emitting function layer 226, the first light emitting function layer 224 is disposed adjacent to the first electrode 221, the second light emitting function layer 225 is disposed adjacent to the second electrode 222, and the second light emitting function layer 225 is disposed between the first light emitting function layer 224 and the third light emitting function layer 226.

Taking the first light emitting function layer 224 as an example, the first light emitting function layer 224 may include a hole transport layer 201, a light emitting material layer 203, and an electron transport layer 205. The light emitting material layer 203 of the first light emitting function layer 224 is located between the hole transport layer 201 and the electron transport layer 205. In addition, the first light-emitting functional layer 224 may further include an electron blocking layer 202 and a hole blocking layer 204, the electron blocking layer 202 is located between the light-emitting material layer 203 and the hole transport layer 201, and the hole blocking layer 204 is located between the light-emitting material layer 203 and the electron transport layer 205. The thickness of the electron blocking layer 202 may be smaller than that of the hole transport layer 201 of each light-emitting functional layer, so as to reduce the thickness of the electron blocking layer 202 and avoid adverse effects on the hole injection efficiency.

The light emitting material layer 203 may include a host material and a guest material. The guest material may be a fluorescent material, and of course, may also be a phosphorescent material, but the disclosure is not limited thereto. Wherein the mass fraction of the guest material in the luminescent material layer 203 is less than 2%. When the concentration of the guest material in the light emitting material layer 203 is too high, the concentration of the generated excitons is also high, so that the excitons are easily quenched, and the mass fraction of the guest material is less than 2% by the present disclosure, so that the problem that the excitons are easily quenched due to the too high concentration of the guest material can be solved. The host material may be an electron transport type material, so that an interface of a carrier recombination region is close to the hole transport layer 201, which is beneficial to improving the light emitting efficiency.

It should be noted that the second light-emitting functional layer 225 and the third light-emitting functional layer 226 are substantially the same as the first light-emitting functional layer 224, and are not described herein again. A few differences exist in that the color of the first light-emitting functional layer 224 and the color of the third light-emitting functional layer 226 are blue, the color of the second light-emitting functional layer 225 is yellow, the blue light is first mixed with the yellow light to form a mixed light, and the mixed light is then mixed with the blue light and emitted.

The light emitting unit 223 further includes a first charge generation layer 227 and a second charge generation layer 228, the first charge generation layer 227 being located between the first light emitting function layer 224 and the second light emitting function layer 225, and the second charge generation layer 228 being located between the second light emitting function layer 225 and the third light emitting function layer 226. Taking the first charge generation layer 227 as an example, the electron transport layer 205 and the hole transport layer 201 are respectively disposed on two sides of the first charge generation layer 227, the N-type charge generation layer in the first charge generation layer 227 is closer to the electron transport layer 205, and the P-type charge generation layer in the first charge generation layer 227 is closer to the hole transport layer 201.

The host material of the first charge generation layer 227 includes an organic material and a resistance adjusting material, and the LUMO level of the host material of the charge generation layer is greater than 2.8eV. The first charge generation layer 227 is an n-type doped layer, and the doping material of the first charge generation layer 227 is an active metal, and may specifically include any one of Yb, cs, and Li.

It should be noted that the second charge generation layer 228 is substantially the same as the first charge generation layer 227, and the description thereof is omitted here.

Note that the material of the resistance adjusting material is the same as that of the electron transit layer 205. Like this can form with molecular structure, more do benefit to the separation after the electric charge produces the layer and produce electric charge, because impedance control material is the same molecular structure and molecular orbit with the material of electron transport layer 205, so after the separation of electron hole produces at electric charge production layer interface, can transfer the electron to the previous light-emitting functional layer fast, the electric charge just can not be too much piled up like this, owing to do not have the energy barrier, the voltage of the consumption on the electric charge production layer also can reduce. It can be understood that, in the light emitting direction, since the thickness of the charge generation layer is small and the injection of charges is optimized, the normal operation voltage of the light emitting device 220 does not increase.

Because the impedance adjusting material is added in the charge generation layer, the transverse transmission impedance of the charge generation layer is increased, and the distance between two adjacent light-emitting devices 220 is far greater than the thickness of the light-emitting devices 220, the current flowing through the light-emitting devices 220 is far greater than the transverse crosstalk current, and the performance loss caused by crosstalk is greatly improved. For a light emitting device 220 with three stacked light emitting functions, the lateral resistance of the second charge generation layer 228 should be greater than that of the first charge generation layer 227, and specifically, the ratio of the lateral resistance of the second charge generation layer 228 to that of the first charge generation layer 227 should be greater than or equal to 2, so as to effectively reduce crosstalk between adjacent light emitting devices 220.

As shown in fig. 3 and 4, the charge generation layer operates on the following principle: under the action of an electric field formed between the first electrode 221 and the second electrode 222, the p-type charge generation layer 2271 (p-type CGL, heavily doped p-type semiconductor) and the n-type charge generation layer 2272 (n-type CGL, heavily doped n-type semiconductor) in the p-n junction type charge generation layer generate a large number of electrons and holes at the interface, and the electrons tend to be transferred to the material with high electron affinity (i.e., n-type semiconductor) and the holes tend to be left in the p-type semiconductor due to the large difference between the electron affinity of the p-type semiconductor and the electron affinity of the n-type semiconductor, so that the generated electrons and holes are separated at the interface. The separated free electrons and holes do drift motion towards two ends of the charge generation layer respectively under the action of an electric field.

Fig. 3 is a schematic diagram of a conventional charge generation layer, and fig. 4 is a schematic diagram of a charge generation layer according to the present disclosure, wherein the energy band of the n-type charge generation layer 2272 according to the present disclosure is shown in a dotted line. The p-type charge generation layer 2271 may include a single first organic material, so the HOMO energy and the LUMO energy may be separately maintained in the p-type charge generation layer 2271. The n-type charge generation layer 2272 may include a second organic material, a resistance-adjusting material, and a doping material, and the HOMO energy and the LUMO energy of the second organic material in the n-type charge generation layer 2272 may be predetermined according to the material of the second organic material. The second organic material may be a main material in the n-type charge generation layer 2272 to help generate and transport electrons, and the impedance modulation material may lower a LUMO level of the n-type charge generation layer 2272 such that a LUMO level position of the n-type charge generation layer 2272 of the present disclosure is deeper than a LUMO level position of the existing n-type charge generation layer 2272. After the separation of electrons and holes, the electrons more easily enter the LUMO level of the electron transport layer 205 (ETL) of the adjacent light emitting functional layer.

The host material of the charge generation layer further includes a photosensitive material and/or a thermosensitive material. The photosensitive material is required to have strong light absorption, and the thermosensitive material is required to have strong heat absorption, but does not affect the charge separation performance of the charge generation layer. After the light-emitting layer 2 is manufactured, the area where each light-emitting device 220 is located in the light-emitting layer 2 is shielded through the mask plate, the area, around the light-emitting function layer, of each light-emitting device 220 is irradiated by the exposure machine, when the main body material of the charge generation layer further comprises a photosensitive material, the charge generation layer absorbs light energy more easily, and when the main body material of the charge generation layer further comprises a thermosensitive material, the charge generation layer absorbs heat energy more easily, so that the difficulty of processing can be reduced. The conductive performance of the charge generation layer at the irradiated position may be deteriorated, so that the lateral impedance of the light emitting device 220 may be much greater than the impedance in the vertical direction, thereby greatly reducing crosstalk and leakage.

The light emitting functional layer may further include at least one carrier injection layer 229. The carrier injection layer 229 may be an Electron Injection Layer (EIL) or a Hole Injection Layer (HIL). When the carrier injection layer 229 is an electron injection layer, the electron injection layer may be positioned on a side of the third light emitting function layer 226 close to the second electrode 222 for lowering a barrier for injecting electrons from the second electrode 222, so that electrons can be efficiently injected from the second electrode 222 into the third light emitting function layer 226. When the carrier injection layer 229 is a hole injection layer, the hole injection layer may be positioned at a side of the first light emission function layer 224 close to the first electrode 221 for lowering a barrier for injecting holes from the first electrode 221, so that holes can be efficiently injected from the first electrode 221 into the first light emission function layer 224.

Therefore, in selecting the material for the electron/hole injection layer, matching of the energy level of the material and the material for the electrode needs to be considered. For example, the electron injection layer material may be LiQ (8-hydroxyquinoline lithium), alQ3 (8-hydroxyquinoline aluminum), or the like; the material of the hole injection layer may be CuPc (polyester carbonate), tiOPc, m-MTDATA, 2-TNATA, or the like.

The first electrode 221 may be an anode of a light emitting element, and the second electrode 222 may be a cathode of the light emitting element. The first electrodes 221 of the different light emitting devices 220 are disconnected from each other in a plane and insulated from each other, and the first electrodes 221 of all the light emitting devices 220 constitute a first conductive layer 21. The second electrodes 222 of the different light emitting devices 220 are of a unitary structure, that is, the second electrodes 222 of the different light emitting devices 220 are of a continuous smooth structure formed by the same conductive material layer, the second electrodes 222 of all the light emitting devices 220 form the second conductive layer 23, and no interface exists between different regions in the second conductive layer 23. All the light emitting cells 223 constitute a light emitting cell layer 22, and the light emitting cell layer 22 is disposed between the first conductive layer 21 and the second conductive layer 23. One of the first electrode 221 and the second electrode 222 is a reflective electrode, and the other is a semi-transparent and semi-reflective electrode. When the first electrode 221 is a transparent electrode or a semi-transparent electrode, or the second electrode 222 is a transparent electrode or a semi-transparent electrode, light is emitted from the transparent electrode or the semi-transparent electrode.

It is understood that one of the first conductive layer 21 and the second conductive layer 23 has reflectivity and the other has semi-permeability or light transmittance. For example, the first electrode 221 and the second electrode 222 in the first light emitting device 2201 form a microcavity, so that the distance from each light emitting functional layer to the reflective layer and the wavelength of the light emitted by the light emitting functional layer satisfy 2 Δ = m λ (m =1,2,3, … …), where Δ is an optical path length which is equal to a medium refractive index multiplied by a distance that the light travels in the medium multiplied by a medium refractive index, thereby causing the emitted light and the reflected light to resonate in the microcavity, thereby improving the purity of light emission and further improving the color gamut and the luminance brightness of the display panel.

Illustratively, the first conductive layer 21 is a high work function material, for example, having high reflectivity, for example, a stacked structure of Ti/Al/Ti/Mo, wherein metal titanium may serve as a buffer layer to improve adhesion between layers, al may serve as a high reflection material, and Mo may serve as a high work function material to directly contact with the organic functional layer to improve carrier injection capability.

The second conductive layer 23 is made of a conductive material with a low work function and a high transmittance, and may be made of a transparent metal oxide conductive material, such as Indium Zinc Oxide (IZO), indium Tin Oxide (ITO), indium Gallium Zinc Oxide (IGZO), or a transparent nano conductive material, such as carbon nanotube, graphene, or nano silver wire.

Fig. 5 shows an example of a cross-sectional view of a display panel. The display panel comprises a driving backplane 1 and a pixel layer, the driving backplane 1 comprises a substrate 10 and a driving circuit layer 100, for the sake of clarity, only a first sub-pixel area and a second sub-pixel area adjacent to the pixel layer are shown in the figure, and for each sub-pixel area, only a light emitting element and a transistor 11 directly connected with the light emitting element in the driving circuit layer 100 are shown. For example, the transistor 11 may be a driving transistor configured to control the magnitude of a current for driving the light emitting element to emit light. For example, the transistor 11 may be a light emission control transistor for controlling whether or not a current for driving the light emitting element to emit light flows. Embodiments of the present disclosure are not limited in this regard.

As shown in fig. 5, the display panel includes a base substrate 10, a first conductive layer 21 disposed on the base substrate 10, an organic functional layer including a carrier injection layer 229, and a second conductive layer 23. The first conductive layer 21 includes first electrodes 221 of the first and second light emitting devices 2201 and 2202 insulated from each other at the first and second sub-pixel regions, respectively, and the first electrodes 221 of the first and second light emitting devices 2201 and 2202 are disconnected from each other. The second conductive layer 23 includes the second electrode 222 of the first light emitting device 2201 and the second electrode 222 of the second light emitting device 2202 connected to each other at the first sub-pixel region and the second sub-pixel region, respectively.

As shown in fig. 5, the display panel provided by the embodiment of the present disclosure uses a silicon substrate as the substrate 10, and the driving circuit layer 100 can be integrated on the silicon substrate to form the driving backplate 1, in this case, since the silicon substrate circuit can achieve higher precision. The first and second light emitting elements are formed on a driving backplate 1, and the driving backplate 1 includes a substrate base plate 10, such as single crystal silicon or high purity silicon, and a driving circuit layer 100 formed on the substrate base plate 10.

The driving circuit layer 100 is formed on the base substrate 10 through a semiconductor process, for example, an active layer 112 (i.e., a semiconductor layer), a first pole 113, and a second pole 114 of the transistor 11 are formed in the base substrate 10 through a doping process, an insulating layer 15 is formed through a silicon oxidation process, and a plurality of third conductive layers 16 are formed through a sputtering process, and the like. The semiconductor layers (e.g., the active layers in fig. 5) of the transistor 11 are located inside the base substrate 10 or are part of the base substrate 10.

As shown in fig. 5, the first light emitting element is electrically connected to the first transistor 12, and the second light emitting element is electrically connected to the second transistor 13. The embodiments of the present disclosure do not limit the specific types of the first transistor 12 and the second transistor 13. The first transistor 12 is exemplarily described below, and the description is also applicable to the second transistor 13, and thus will not be described again.

The first electrode 221 of the first light emitting element is formed on the surface of the driving backplane 1, and is electrically connected to the first electrode 113 of the first transistor 12 through the contact hole 14 filled with a conductive material (e.g., tungsten) and the plurality of conductive layers. Fig. 5 exemplarily shows one insulating layer 15 and two third conductive layers 16, however, the number of layers of the insulating layer 15 and the conductive layers is not limited by the embodiments of the present disclosure.

For example, the first transistor 12 includes a gate electrode 111, a gate insulating layer 115, an active layer 112, a first pole 113, and a second pole 114. Embodiments of the present disclosure do not limit the type, material, and structure of the first transistor 12, for example, it may be a top gate type, a bottom gate type, and the like, and the active layer 112 of the first transistor 12 may be an inorganic semiconductor material such as microcrystalline silicon, amorphous silicon, polycrystalline silicon (low temperature polycrystalline silicon or high temperature polycrystalline silicon), an oxide semiconductor (e.g., IGZO), or may also be an organic semiconductor material such as PBTTT, PDBT-co-TT, PDQT, PDVT-10, dinaphtho-bithiophene (DNTT), or pentacene. For example, the first transistor 12 may be N-type or P-type.

Some embodiments of the present disclosure are illustrated with a field effect transistor (e.g., a MOS field effect transistor) formed in a silicon substrate, in which the silicon substrate is doped (p-type doped or n-type doped) to form the active layer 112 of the transistor, i.e., the active layer 112 of the transistor is located within the silicon substrate, or the active layer 112 of the transistor is a portion of the silicon substrate. The source and drain of the transistor used herein may be symmetrical in structure, so that there may be no difference in structure between the source and drain. In the embodiment of the present disclosure, in order to distinguish two poles of a transistor other than a gate, for example, one of them may be directly described as a first pole 113, and the other as a second pole 114.

The topmost conductive layer in the driving backplate 1 may be reflective, for example a titanium/titanium nitride/aluminium stack. For example, the conductive layer includes a plurality of sub-layers disposed at intervals, and the sub-layers are disposed in one-to-one correspondence with the first electrodes 221 included in the first conductive layer 21. In the top emission structure, the conductive layer may be configured as a reflective layer for reflecting light emitted by the light emitting element, thereby improving light extraction efficiency. For example, the orthographic projection of each electrode in the first conductive layer 21 on the base substrate 10 falls within the orthographic projection of the portion of the conductive layer corresponding to that electrode on the base substrate 10. In this case, the first conductive layer 21 may employ a transparent conductive oxide material having a high work function, such as ITO, IZO, IGZO, AZO, or the like.

The light emitting layer 2 of the pixel layer includes first and second light emitting devices 2201 and 2202 respectively located in the first and second sub-pixel regions. Each of the first and second light emitting devices 2201 and 2202 includes a light emitting cell 223, and the light emitting cell 223 is opposite to the first and second electrodes 221 and 222. For example, the first light emitting device 2201 and the second light emitting device 2202 may be Organic Light Emitting Diodes (OLEDs) or quantum dot light emitting diodes (QLEDs), etc., and the disclosed embodiments are not limited to the type of light emitting elements. For example, the light emitting unit 223 may be a small molecule organic material or a high molecule organic material.

For example, the first and second light emitting devices 2201 and 2202 have a top emission structure, and the first and second electrodes 221 and 222 have reflectivity. For example, the first electrode 221 includes a high work function and high reflectivity material to serve as an anode, such as a stack structure of Ti/Al/Ti/Mo, in which metallic titanium may serve as a buffer layer to improve interlayer adhesion, al may serve as a high reflectivity material, and Mo may serve as a high work function material to directly contact the organic functional layer to improve carrier injection capability. Accordingly, the second conductive layer 23 serves as a cathode, and the second conductive layer 23 may be a transparent conductive material or a stacked-layer structure of a transparent conductive material and a metal material, for example. For example, the second conductive layer 23 may be a transparent metal oxide conductive material, such as Indium Zinc Oxide (IZO), indium Tin Oxide (ITO), indium Gallium Zinc Oxide (IGZO), or a transparent nano conductive material, such as carbon nanotube, graphene, or nano silver wire.

It should be noted that the transistors 11 employed in the embodiments of the present disclosure may be thin film transistors, field effect transistors, or other switching devices with the same characteristics. When the transistor 11 is a thin film transistor, the driving circuit layer 100 may include a plurality of driving circuit units, any one of the driving circuit units may include the transistor 11 and a storage capacitor, and the plurality of driving circuit units constitute the driving circuit layer 100.

Fig. 6 shows another display panel, in which a driving circuit layer 100 is disposed on a substrate 10, a pixel layer is disposed on a side of the driving circuit layer 100 away from the substrate 10, the driving circuit layer 100 includes a thin film transistor, and a buffer layer 18 may be disposed between the driving circuit layer 100 and the substrate 10.

When the transistor 11 is a thin film transistor, the substrate 10 may be an inorganic substrate or an organic substrate. For example, in one embodiment of the present disclosure, the material of the substrate base plate 10 may be a glass material such as soda-lime glass (soda-lime glass), quartz glass, sapphire glass, or a metal material such as stainless steel, aluminum, nickel, or the like.

In another embodiment of the present disclosure, the material of the substrate 10 may be Polymethyl methacrylate (PMMA), polyvinyl alcohol (PVA), polyvinyl phenol (PVP), polyether sulfone (PES), polyimide, polyamide, polyacetal, polycarbonate (PC), polyethylene terephthalate (PET), polyethylene naphthalate (PEN), or a combination thereof.

In another embodiment of the present disclosure, the substrate 10 may also be a flexible substrate, for example, the material of the substrate 10 may be Polyimide (PI). The base substrate 10 may also be a composite of multiple layers of materials, for example, in one embodiment of the present disclosure, the base substrate 10 may include a Bottom Film layer (Bottom Film), a pressure sensitive adhesive layer, a first polyimide layer, and a second polyimide layer, which are sequentially stacked.

The thin film transistor may be selected from a top gate thin film transistor, a bottom gate thin film transistor, or a double gate thin film transistor, and the top gate thin film transistor is exemplified.

The thin film transistor may include an active layer 112, a gate insulating layer 115, a gate electrode 111, a source electrode, and a drain electrode, wherein:

the active layer 112 is disposed on one side of the substrate 10, and may be made of polysilicon, amorphous silicon, or the like, and the active layer 112 may include a channel region and source and drain regions of two different doping types located at both sides of the channel region. Wherein the channel region may retain semiconductor properties and the semiconductor material of the source and drain regions is partially or fully conductible.

The gate insulating layer 115 may cover the active layer 112 and the substrate base plate 10, and the material of the gate insulating layer 115 is an insulating material such as silicon oxide.

The gate 111 is disposed on a side of the gate insulating layer 115 away from the substrate 10, and is opposite to the active layer 112, that is, a projection of the gate 111 on the substrate 10 is located within a projection range of the active layer 112 on the substrate 10, for example, the projection of the gate 111 on the substrate 10 is overlapped with a projection of a channel region of the active layer 112 on the substrate 10.

When the transistor 11 is a thin film transistor, the insulating layer 15 includes an interlayer dielectric layer 151, the interlayer dielectric layer 151 is disposed on a side of the gate 111 away from the substrate 10, the interlayer dielectric layer 151 covers the gate 111 and the gate insulating layer 115, and the interlayer dielectric layer 151 is an insulating material.

A source and a drain are disposed on the surface of the interlayer dielectric layer 151 away from the substrate base plate 10, and the source and the drain are connected to the active layer 112, for example, the source and the drain are respectively connected to a source region and a drain region of the corresponding active layer 112 through vias.

The insulating layer 15 further includes a protective layer 152, the protective layer 152 is disposed on a side of the source and drain away from the substrate 10, and the protective layer 152 covers the source and drain. The insulating layer 15 further includes a planarization layer 153, the planarization layer 153 is disposed on the source and drain sides away from the substrate 10, the planarization layer 153 is disposed on the protective layer 152 side away from the substrate 10, the planarization layer 153 covers the protective layer 152, and the surface of the planarization layer 153 away from the substrate 10 is a plane.

The different light emitting devices 220 are controlled to emit light by the driving circuit layer 100, so that the pixel layer performs a function of image display. Specifically, the source electrode may be connected to the first electrode 221 of the light emitting device 220, and the light emitting device 220 may be driven to emit light by applying a signal to the first electrode 221, and a specific light emitting principle will not be described in detail herein. At least a portion of the light emitting device 220 may be any of the stacked electroluminescent devices described above, and the structure and materials thereof have been described in detail, and thus will not be described in detail.

And the side of the pixel layer far away from the substrate base plate 10 is provided with an encapsulation layer group 4, so that the pixel layer is coated to prevent water and oxygen corrosion. The encapsulation layer group 4 may have a single-layer or multi-layer structure, and the material of the encapsulation layer group 4 may include an organic or inorganic material, which is not particularly limited herein.

In this embodiment, the encapsulation layer group 4 may include a first inorganic encapsulation layer 41, an organic encapsulation layer 42 and a second inorganic encapsulation layer 43, the first inorganic encapsulation layer 41 is disposed on a side of the pixel layer away from the substrate 10, the organic encapsulation layer 42 is disposed on a side of the first inorganic encapsulation layer 41 away from the substrate 10, and the second inorganic encapsulation layer 43 is disposed on a side of the organic encapsulation layer 42 away from the substrate 10.

The color film layer 3 can be arranged on one side of the packaging layer group 4 far away from the driving backboard 1, the color film layer 3 comprises a packaging substrate 33, a black matrix 31 is arranged on one side of the packaging substrate 33, an opening area array is defined on the black matrix 31 and comprises a plurality of opening area rows arranged along the row direction, each opening area row comprises a plurality of opening areas, a sub-filtering unit 32 is arranged in each opening area, two adjacent sub-filtering units 32 in each opening area row are different in color, the plurality of sub-filtering units 32 in the same opening area row form the plurality of filtering units 32, and generally, one filtering unit 32 can comprise a red sub-filtering unit, a green sub-filtering unit and a blue sub-filtering unit.

The disclosed embodiments also provide a display device, which may include the display panel of any one of the above embodiments of the present disclosure. The detailed structure and advantages of the display panel have been described in detail earlier, and therefore, the detailed description thereof is omitted here.

It should be noted that the display device includes other necessary components and components besides the display panel, such as a housing, a circuit board, a power line, and the like, and those skilled in the art can supplement the display device accordingly according to the specific use requirement of the display device, and the description thereof is omitted.

When the display panel has the structure shown in fig. 6, the display device may be a conventional electronic device, such as: mobile phones, computers, televisions and video cameras. When the display panel has the structure shown in fig. 5, the display device may also be an emerging wearable device, such as: virtual reality devices and augmented reality devices, not to be enumerated herein.

Other embodiments of the disclosure will be apparent to those skilled in the art from consideration of the specification and practice of the disclosure disclosed herein. This application is intended to cover any variations, uses, or adaptations of the disclosure following, in general, the principles of the disclosure and including such departures from the present disclosure as come within known or customary practice within the art to which the disclosure pertains. It is intended that the specification and examples be considered as exemplary only, with a true scope and spirit of the disclosure being indicated by the following claims.

Claims (13)

1. A display panel comprising a plurality of stacked electroluminescent devices, the stacked electroluminescent devices comprising:

a first electrode;

a second electrode disposed opposite to the first electrode;

the light-emitting unit is arranged between the first electrode and the second electrode and comprises at least two light-emitting functional layers, the at least two light-emitting functional layers are arranged at intervals, and a charge generation layer is arranged between every two adjacent light-emitting functional layers;

the host material of the charge generation layer comprises an organic material and a resistance regulation material, and the LUMO energy level of the host material of the charge generation layer is more than 2.8eV.

2. The display panel according to claim 1, wherein the light-emitting functional layer comprises a hole transport layer, an electron blocking layer, a light-emitting material layer, a hole blocking layer, and an electron transport layer, which are sequentially stacked in a direction from the first electrode to the second electrode.

3. The display panel according to claim 2, wherein the impedance-controlling material is the same as a material of the electron transport layer.

4. The display panel according to claim 1, wherein the host material of the charge generation layer further comprises a photosensitive material and/or a thermosensitive material.

5. The display panel according to claim 1, wherein the charge generation layer comprises an n-type charge generation layer, the n-type charge generation layer comprises the resistance control material, the n-type charge generation layer further comprises a doping material, and the doping material of the n-type charge generation layer is an active metal.

6. The display panel according to claim 1, wherein the light emitting unit includes a first light emitting functional layer provided adjacent to the first electrode, a second light emitting functional layer provided adjacent to the second electrode, and a third light emitting functional layer provided between the first light emitting functional layer and the third light emitting functional layer; the light emitting unit includes a first charge generation layer between the first light emitting function layer and the second light emitting function layer and a second charge generation layer between the second light emitting function layer and the third light emitting function layer.

7. The display panel according to claim 6, wherein a ratio of a lateral resistance of the second charge generation layer to a lateral resistance of the first charge generation layer is 2 or more.

8. The display panel according to claim 1, wherein one of the first electrode and the second electrode is a reflective electrode and the other is a transflective electrode.

9. The display panel according to claim 1, wherein a distance between adjacent two of the laminated electroluminescent devices is larger than a thickness of the laminated electroluminescent devices.

10. A method for manufacturing a display panel includes preparing a plurality of laminated electroluminescent devices, and the preparing of the laminated electroluminescent devices includes:

forming a first electrode;

forming a light emitting unit on one side of the first electrode, including: forming at least two light-emitting function layers, forming a charge generation layer between every two adjacent light-emitting function layers, wherein the host material of the charge generation layer comprises an organic material and a resistance regulation material, and the LUMO energy level of the host material of the charge generation layer is more than 2.8eV;

and forming a second electrode on one side of the light-emitting unit far away from the first electrode.

11. The method according to claim 10, wherein the charge generation layer further includes a dopant material, and the organic material, the impedance control material, and the dopant material of the charge generation layer are formed on the light-emitting functional layer by triple-source co-evaporation.

12. The method for manufacturing a display panel according to claim 10, wherein the host material of the charge generation layer further includes a photosensitive material and/or a thermosensitive material, the method further comprising: and shielding the light-emitting function layer of each laminated electroluminescent device by a mask plate, and carrying out photoetching or thermal etching on the periphery of the light-emitting function layer of each laminated electroluminescent device.

13. A display device characterized by comprising the display panel according to any one of claims 1 to 9.

Images