Display panel and manufacturing method thereof, and display device

Abstract

The embodiment of the present application provides a display panel and a method for manufacturing the same, and a display device, belonging to the field of display technology, comprising: a substrate, and an electron transport layer and a light-emitting layer stacked on one side of the substrate; wherein the electron transport layer at least includes an electron blocking layer, and the electron blocking layer includes a non-fullerene acceptor material. The display panel and a method for manufacturing the same, and a display device provided by the embodiment of the present application can improve the problem of imbalance between charge injection and hole injection.

Description

Technical Field

[0001] The embodiments of the present application relate to the field of display technology, and more specifically, to a display panel and a method for manufacturing the same, and a display device. Background Art

[0002] Colloidal quantum dots (QD) have the characteristics of narrow luminescence peak, adjustable luminescence spectrum size, high luminescence efficiency, etc., which can bring wide color gamut and high brightness display effects. In addition, they can be processed in solution, which can reduce production costs. Therefore, quantum dot light-emitting diodes (QLEDs) have received extensive attention from major universities and enterprises and have broad development prospects.

[0003] At present, QLED devices generally adopt inorganic / organic hybrid structures, including zinc oxide (ZnO) electron transport layer and organic hole transport layer. However, the hole mobility of most organic hole transport materials is lower than the electron mobility of ZnO. In addition, the QD valence band is deep and the hole injection barrier is high. Therefore, most QLED devices have the problem of unbalanced charge injection, which limits the further improvement of efficiency and lifespan. Summary of the invention

[0004] The embodiments of the present application provide a display panel and a method for manufacturing the same, and a display device, aiming to improve the problem of imbalance between charge injection and hole injection.

[0005] A first aspect of an embodiment of the present application provides a display panel, including:

[0006] A substrate, and an electron transport layer and a light emitting layer stacked on one side of the substrate;

[0007] Wherein, the electron transport layer at least includes an electron blocking layer, and the electron blocking layer includes a non-fullerene acceptor material.

[0008] Optionally, the non-fullerene receptor material includes at least one of the following: a naphthalene diimide polymer receptor, a perylene diimide receptor, an ADA type receptor, and an A-DAD-A receptor.

[0009] Optionally, the electron transport layer further includes a transport layer stacked with the electron blocking layer, and the electron mobility of the electron blocking layer is smaller than the electron mobility of the transport layer.

[0010] Optionally, the electron transport layer further includes a first transport layer and a second transport layer;

[0011] Wherein, the electron blocking layer is arranged between the first transport layer and the second transport layer.

[0012] Optionally, the second transmission layer is close to the light-emitting layer;

[0013] The material of the first transmission layer includes ZnO;

[0014] The material of the second transmission layer includes ZnO doped with Mg, Ga or Sn.

[0015] Optionally, the electron transport layer further includes a third transport layer;

[0016] Wherein, the electron blocking layer is arranged between the third transport layer and the light-emitting layer.

[0017] Optionally, the electron blocking layer selectively transmits light emitted by the light-emitting layer.

[0018] A second aspect of the embodiments of the present application provides a display device, comprising the display panel provided in the first aspect of the embodiments of the present application.

[0019] A third aspect of an embodiment of the present application provides a method for manufacturing a display panel, the method comprising:

[0020] providing a substrate;

[0021] forming an electron transport layer on one side of the substrate;

[0022] forming a light-emitting layer on a side of the electron transport layer facing away from the substrate;

[0023] Wherein, the electron transport layer at least includes an electron blocking layer, and the electron blocking layer includes a non-fullerene acceptor material.

[0024] Optionally, the electron transport layer includes a transport layer stacked with the electron blocking layer; in the step of forming the electron transport layer on the substrate, the preparation method includes:

[0025] The transport layer and the electron blocking layer are formed by a solution spin coating process, wherein a solvent of the transport layer and a solvent of the electron blocking layer have orthogonal characteristics.

[0026] Beneficial effects:

[0027] The present application provides a display panel and a method for preparing the same, and a display device, which are provided with a substrate, an electron transport layer and a light-emitting layer, wherein the electron transport layer at least includes an electron blocking layer, and the electron blocking layer includes a non-fullerene acceptor material; the electron blocking layer made of the non-fullerene acceptor material can transmit electrons while having a higher minimum vacant energy level, thereby increasing the electron injection barrier, reducing the number of electron injections, and thereby improving the problem of imbalance between charge injection and hole injection. BRIEF DESCRIPTION OF THE DRAWINGS

[0028] In order to more clearly illustrate the technical solutions of the embodiments of the present application, the drawings required for use in the description of the embodiments of the present application will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present application. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying any creative labor.

[0029] Figure 1 is a structural schematic diagram of a display panel proposed in one embodiment of the present application;

[0030] Figure 2 is a schematic structural diagram of another display panel proposed in an embodiment of the present application;

[0031] Figure 3 It is a flowchart of the steps of a method for preparing a display panel proposed in one embodiment of the present application.

[0032] Explanation of the accompanying drawings: 10, substrate; 11, anode; 12, light-emitting layer; 13, hole transport layer; 14, hole injection layer; 15, cathode; 20, electron transport layer; 201, first transport layer; 202, second transport layer; 203, third transport layer; 204, electron blocking layer. DETAILED DESCRIPTION

[0033] The following will be combined with the drawings in the embodiments of the present application to clearly and completely describe the technical solutions in the embodiments of the present application. Obviously, the described embodiments are part of the embodiments of the present application, not all of the embodiments. Based on the embodiments in the present application, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of this application.

[0034] In the related technology, QLED devices generally adopt an inorganic / organic hybrid structure, including a zinc oxide (ZnO) electron transport layer and an organic hole transport layer. However, the hole mobility of most organic hole transport materials is lower than the electron mobility of the electron transport layer. In addition, the quantum dot valence band is deep and the hole injection barrier is high. Therefore, most QLED devices have the problem of unbalanced charge injection, which limits the further improvement of efficiency and lifespan.

[0035] To address this issue, many works start from the device structure and insert an electron blocking layer between the electron transport layer and the quantum dots to reduce electron injection, such as inserting an insulating intermediate layer of PMMA, or introducing a second electron transport layer such as ZnMgO or SnO2. Due to its lower electron mobility and improved valence band, it can also play a role in blocking electrons and improve the injection balance.

[0036] However, the insulating intermediate layer is highly dependent on the film thickness, and the device efficiency can only be improved when it is very thin. When the critical film thickness is exceeded, the device efficiency will be significantly reduced. Although the introduction of other inorganic metal oxide layers on the electron transport layer can achieve the purpose of regulating electron injection, the solvent between the double-layer electron transport layer usually does not have orthogonal properties. The deposition of the upper metal oxide layer may erode the lower electron transport layer, thereby bringing process uncertainty.

[0037] In view of this, the embodiments of the present application propose a display panel and a preparation method thereof, and a display device, by setting a substrate, an electron transport layer and a light-emitting layer, wherein the electron transport layer at least includes an electron blocking layer, and the electron blocking layer includes a non-fullerene acceptor material; the electron blocking layer made of the non-fullerene acceptor material has a higher minimum vacant energy level while being able to transport electrons, thereby increasing the electron injection barrier, reducing the number of electron injections, and thereby improving the problem of imbalance between charge injection and hole injection.

[0038] Reference Figure 1 As shown, a display panel disclosed in an embodiment of the present application includes a substrate 10 and an electron transport layer 20 and a light-emitting layer 12 stacked on one side of the substrate 10 .

[0039] Specifically, the substrate 10 may include a rigid substrate 10 or a flexible substrate 10. For example, when the product has a certain rigidity requirement, the substrate 10 may be made of a rigid material, such as glass, polycarbonate (PC), polymethyl methacrylate (PMMA), etc.; when the product has a foldable, bendable or rollable requirement, the substrate 10 may be made of a flexible material, such as polyethylene terephthalate (PET), colorless polyimide (CPI), etc.

[0040] At the same time, refer to Figure 1 As shown, the display panel may also include an anode 11, a hole transport layer 13, a hole injection layer 14 and a cathode 15 stacked on the substrate 10. The anode 11 is arranged close to the substrate 10, the electron transport layer 20 and the light-emitting layer 12 may be formed on the side of the anode 11 away from the substrate 10, and the hole transport layer 13, the hole injection layer 14 and the cathode 15 are sequentially formed on the side of the light-emitting layer 12 away from the substrate 10. In addition, the light-emitting layer 12 is made of quantum dot material. When displaying light, electrons and holes enter the light-emitting layer 12 from the electron transport layer 20 and the hole transport layer 13 respectively, and cause the quantum dots contained in the light-emitting layer 12 to emit light.

[0041] It should be noted that the display panel has an upright structure. In some feasible implementations, the display panel may also have an inverted structure, that is, the hole injection layer 14 is close to the anode 11 and the electron transport layer 20 is close to the cathode 15. No further details will be given here.

[0042] Furthermore, the electron transport layer 20 at least includes an electron blocking layer 204 , and the electron blocking layer 204 includes a non-fullerene material.

[0043] Specifically, the non-fullerene receptor material can be selected from polymer or small molecule receptor materials. Among them, polymer receptor materials can include naphthalene diimide polymer receptors, such as N2200, PZ1, PBN-12, etc.; small molecule receptor materials can include perylene diimide receptors, such as SF-PDI2, S (TPA-PDI), SF-PDI4, SCPDT-PDI4, Ph-PDI, FTTB-PDI4, etc.; and ADA type receptors, such as ITIC, IEIC, IEICO-4F, IT-4F, etc.; and A-DAD-A receptors, such as Y6, AQx-1, BTP-4Cl, BTP-eC9, etc.

[0044] In practical applications, different non-fullerene acceptor materials can be selected according to different situations of quantum dot light-emitting diodes to make the electron blocking layer 204. For example, for visible light quantum dot light-emitting diodes, non-fullerene acceptor materials with weak absorption in the visible light region, that is, good visible light transmittance (its main absorption band is required to be located in the near-infrared region) are preferably used as the electron blocking layer 204, such as Y series acceptors Y6, AQx-1, BTP-4Cl, BTP-eC9, etc., to reduce the optical loss of the device; for near-infrared quantum dot light-emitting diodes, non-fullerene acceptor materials with no absorption in the near-infrared region (its absorption is required to be located in the visible light region, and the optical band gap is greater than 1.8 eV), such as perylene diimide acceptors SF-PDI2, S (TPA-PDI), SF-PDI4, SCPDT-PDI4, Ph-PDI, FTTB-PDI4, etc., to reduce the optical loss of the device.

[0045] Non-fullerene acceptor materials usually have a relatively high minimum unoccupied (LUMO) energy level (-3.7 to -4.1 eV). During the electron transfer process, they can increase the electron injection barrier, thereby reducing the electrons injected into the light-emitting layer 12, thereby improving the imbalance between charge injection and hole injection, and improving the efficiency and service life of the display device.

[0046] In addition, the non-fullerene acceptor material has electron transport capability, which can eliminate the film thickness dependence of the electron blocking layer 204; at the same time, the commonly used non-fullerene acceptor materials are soluble in chlorinated solvents such as chloroform, chlorobenzene, etc., but insoluble in alcohol solvents, thereby satisfying the orthogonal solvent characteristics to prepare the electron transport layer 20 by a multilayer solution method; the non-fullerene acceptor materials are rich in variety, and they have adjustable absorption, energy level and electron mobility, so they can be selected according to the carrier characteristics and electroluminescent characteristics of the display device, enriching the product demand.

[0047] Furthermore, the electron transport layer 20 may also include a transport layer stacked with the electron blocking layer 204, where the transport layer is used to normally transport electrons, and the electron mobility of the electron blocking layer 204 is less than the electron mobility of the transport layer, which can further reduce the injection of electrons, thereby better balancing the charge injection and hole injection.

[0048] Furthermore, since the non-fullerene acceptor material has light absorption capability, the electron blocking layer 204 can selectively transmit the light emitted by the luminescent layer 12. However, by adjusting the absorption spectrum, the electron blocking layer 204 can have a weaker absorption capability for light of a specific wavelength, which will not affect the light emission of the luminescent layer 12.

[0049] In an optional embodiment, referring to Figure 1 As shown, an embodiment of the present application further provides a display panel, in which the electron transport layer 20 further includes a first transport layer 201 and a second transport layer 202 .

[0050] Specifically, the electron blocking layer 204 is disposed between the first transport layer 201 and the second transport layer 202 , and the first transport layer 201 is disposed close to the substrate 10 , and the second transport layer 202 is disposed close to the light emitting layer 12 .

[0051] The first transport layer 201 can be used to normally realize the transmission of electrons, and the second transport layer 202 can prevent the electron blocking layer 204 from directly contacting the light-emitting layer 12, thereby avoiding charge transfer between the non-fullerene acceptor material and the quantum dots of the light-emitting layer 12, and ensuring the normal light emission of the light-emitting layer 12.

[0052] Furthermore, the material of the first transmission layer 201 may include ZnO; the material of the second transmission layer 202 may include ZnO doped with Mg, Ga, Sn, etc., or may include undoped ZnO. In practical applications, the second transmission layer 202 is preferably doped with ZnO, which can reduce the exciton quenching of the second transmission layer 202 on the quantum dots in the light-emitting layer 12, thereby ensuring the light-emitting efficiency of the quantum dots.

[0053] In an optional embodiment, referring to Figure 2 As shown, the embodiment of the present application further provides a display panel, in which the electron transport layer 20 further includes a third transport layer 203 .

[0054] Specifically, when the quantum dot emission band is in the near-infrared region, a non-fullerene acceptor material with an optical band gap greater than 1.8 eV can be selected as the electron blocking layer 204, and in this embodiment, the electron blocking layer 204 is located between the third transport layer 203 and the light-emitting layer 12, that is, the side of the electron blocking layer 204 facing away from the third transport layer 203 is directly in contact with the light-emitting layer 12.

[0055] Since the optical band gap of the quantum dots is narrower than the optical band gap of the non-fullerene acceptor material included in the electron blocking layer 204 , energy transfer from the quantum dots to the non-fullerene acceptor material does not occur.

[0056] Based on the same inventive concept, an embodiment of the present application discloses a display device, including any display panel as described above in the implementation of the present application.

[0057] Specifically, the display device may further include a cover plate and a driving circuit for driving the display panel to emit light, etc., which will not be elaborated herein.

[0058] Exemplarily, the display device may include a display, a tablet computer, a mobile device such as a mobile phone, a wearable device such as a watch, a VR device, etc. Those skilled in the art may make corresponding selections according to the specific purpose of the display device, which will not be elaborated here.

[0059] Figure 3 A flowchart of a method for preparing a display panel is shown. Figure 3 As shown, the embodiment of the present application discloses a method for preparing a display panel, the method comprising:

[0060] Step 101: Provide a substrate 10.

[0061] Specifically, the substrate 10 may include a rigid substrate 10 or a flexible substrate 10. The steps of completing the manufacturing of the substrate 10 may also include completing the manufacturing of the anode 11.

[0062] Step 102: forming an electron transport layer 20 on one side of the substrate 10, wherein the electron transport layer 20 at least includes an electron blocking layer 204, and the electron blocking layer 204 includes a non-fullerene acceptor material.

[0063] Specifically, when the electron transport layer 20 also includes a transport layer, in the step of forming the electron transport layer 20 on the substrate 10, the transport layer and the electron blocking layer 204 can be formed by a solution spin coating process, and the solvent of the transport layer and the solvent of the electron blocking layer 204 have orthogonal characteristics, so no corrosion will occur during the preparation process.

[0064] Step 103 : forming a light-emitting layer 12 on the side of the electron transport layer 20 facing away from the substrate 10 .

[0065] Specifically, the step of completing the production of the light-emitting layer 12 may also include completing the production of the hole transport layer 13 , the hole injection layer 14 and the cathode 15 .

[0066] The display panel prepared by the above preparation method has an electron blocking layer 204 made of non-fullerene acceptor material that can transmit electrons and has a higher minimum vacancy energy level, thereby increasing the electron injection barrier, reducing the number of electron injections, and further improving the problem of imbalance between charge injection and hole injection.

[0067] It should be noted that the various embodiments in this specification are described in a progressive manner, and each embodiment focuses on the differences from other embodiments. The same or similar parts between the various embodiments can be referenced to each other.

[0068] It should also be noted that, in this article, the orientation or position relationship indicated by the terms "center", "up", "down", "left", "right", "vertical", "horizontal", "inside", "outside", etc. is based on the orientation or position relationship shown in the drawings, which is only for the convenience of describing the present application and simplifying the description, and does not indicate or imply that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore cannot be understood as a limitation on the present application. In addition, relational terms such as "first" and "second" are only used to distinguish one entity or operation from another entity or operation, and do not necessarily require or imply that there is any such actual relationship or order between these entities or operations, nor can they be understood as indicating or implying relative importance. Moreover, the terms "include", "comprise" or any other variant thereof are intended to cover non-exclusive inclusion, so that a process, method, article or terminal device including a series of elements includes not only those elements, but also includes other elements not explicitly listed, or also includes elements inherent to such process, method, article or terminal device. Without more restrictions, an element defined by the phrase "comprising a ..." does not exclude the existence of other identical elements in the process, method, article or terminal device comprising the element.

[0069] The technical solution provided by the present application is described in detail above. The principle and implementation method of the present application are described in this article using specific examples. The description of the above embodiments is only used to help understand the present application, and the content of this specification should not be understood as limiting the present application. At the same time, for those of ordinary skill in the art, according to the present application, there will be different forms of changes in the specific implementation methods and application scopes. It is not necessary and impossible to list all the implementation methods here, and the obvious changes or modifications derived therefrom are still within the scope of protection of the present application.

Claims

1. A display panel, characterized in that: include: A substrate, and an electron transport layer and a light emitting layer stacked on one side of the substrate; Wherein, the electron transport layer at least includes an electron blocking layer, the electron blocking layer includes a non-fullerene acceptor material, and the non-fullerene acceptor material includes at least one of the following: a naphthalene diimide polymer acceptor, a perylene diimide acceptor, an ADA type acceptor, and an A-DAD-A acceptor.

2. The display panel according to claim 1, characterized in that: The electron transport layer further includes a transport layer stacked with the electron blocking layer, and the electron mobility of the electron blocking layer is smaller than the electron mobility of the transport layer.

3. The display panel according to claim 1, wherein: The electron transport layer further includes a first transport layer and a second transport layer; Wherein, the electron blocking layer is arranged between the first transport layer and the second transport layer.

4. The display panel according to claim 3, characterized in that: The second transmission layer is close to the light emitting layer; The material of the first transmission layer includes ZnO; The material of the second transmission layer includes ZnO doped with Mg, Ga or Sn.

5. The display panel according to claim 1, wherein: The electron transport layer further includes a third transport layer; Wherein, the electron blocking layer is arranged between the third transport layer and the light-emitting layer.

6. The display panel according to claim 1, characterized in that: The electron blocking layer selectively transmits the light emitted by the light emitting layer.

7. A display device, characterized in that: Comprising the display panel as claimed in any one of claims 1 to 6.

8. A method for preparing a display panel, characterized in that: The preparation method comprises: providing a substrate; forming an electron transport layer on one side of the substrate; forming a light-emitting layer on a side of the electron transport layer facing away from the substrate; Wherein, the electron transport layer at least includes an electron blocking layer, the electron blocking layer includes a non-fullerene acceptor material, and the non-fullerene acceptor material includes at least one of the following: a naphthalene diimide polymer acceptor, a perylene diimide acceptor, an ADA type acceptor, and an A-DAD-A acceptor.

9. The method for preparing a display panel according to claim 8, characterized in that: The electron transport layer includes a transport layer stacked with the electron blocking layer; in the step of forming the electron transport layer on the substrate, the preparation method includes: The transport layer and the electron blocking layer are formed by a solution spin coating process, wherein a solvent of the transport layer and a solvent of the electron blocking layer have orthogonal characteristics.

Images