CN113451521A

CN113451521A - Quantum dot light-emitting diode device, preparation method thereof and display panel

Info

Publication number: CN113451521A
Application number: CN202110607441.8A
Authority: CN
Inventors: 彭争春; 王为高; 徐秀茹
Original assignee: Shenzhen University
Current assignee: Shenzhen University
Priority date: 2021-06-01
Filing date: 2021-06-01
Publication date: 2021-09-28

Abstract

The application relates to a quantum dot light-emitting diode device, a preparation method thereof and a display panel, wherein the quantum dot light-emitting diode device comprises a substrate, a cathode layer, a light-emitting layer and an anode layer which are sequentially stacked, wherein the light-emitting layer is multi-layer, each light-emitting layer is stacked, a silver nanowire film is formed between adjacent light-emitting layers, the silver nanowire film is used as an intermediate connecting layer of the adjacent light-emitting layers, the silver nanowire film has excellent conductivity and light transmittance, the carrier generation capacity of the connecting layers can be remarkably enhanced, and therefore the working performance of the quantum dot light-emitting diode device is effectively improved.

Description

Quantum dot light-emitting diode device, preparation method thereof and display panel

Technical Field

The application relates to the technical field of display, in particular to a quantum dot light-emitting diode device, a preparation method thereof and a display panel.

Background

Quantum dot light emitting diodes (QLEDs) have the advantages of self-emission, tunable spectrum, high color purity, and applicability to flexible displays, and have received much attention in recent years. Since the first QLEDs reported, researchers have dramatically improved the efficiency of QLEDs by optimizing materials and device structures, but their performance is still far lower than that of the organic light emitting diodes that have been commercialized. Therefore, it is necessary to develop a new strategy to improve the performance of QLEDs, and a device structure in which two or more layers of QLEDs are connected through a connection layer to form a stacked layer is an effective method because the current efficiency and external quantum efficiency of the stacked QLEDs can be improved by times compared with those of a single qled device, and higher brightness can be realized at lower current density, which is beneficial to improving the service life of QLEDs. And, by changing the composition of the light emitting layer in each light emitting cell, emission of a plurality of light colors can be achieved.

In recent years, the laminated QLEDs have been developed, and the device efficiency is greatly improved compared with that of a single qled device, but at the same time, some problems exist to limit the further improvement of the device performance. The connection layer as a functional layer for connecting adjacent light emitting units has a great influence on the performance of the device, and particularly, the carrier generation layer in the connection layer needs to have good optical transmittance and carrier generation capability. The carrier generation layer can be prepared by: (1) a thin-layer metal electrode is evaporated to be used as a transparent carrier generation layer, but the optical transmittance of metal is poor; (2) the organic conductive material is prepared by spin coating of a solution, but the carrier generation capability of the organic conductive material is poor. Therefore, the carrier generation layers of both materials described above may hinder further improvement of the performance of the stacked QLEDs.

Disclosure of Invention

In view of the above, it is necessary to provide a quantum dot light emitting diode device having high efficiency operation performance.

The quantum dot light-emitting diode device of the embodiment comprises a substrate, a cathode layer, a light-emitting layer and an anode layer which are sequentially stacked, wherein the light-emitting layer is multi-layer, each light-emitting layer is stacked, a silver nanowire thin film is formed between every two adjacent light-emitting layers, the silver nanowire thin films are used as intermediate connecting layers of the adjacent light-emitting layers, the silver nanowire thin films have excellent conductivity and light transmittance, the carrier generation capacity of the connecting layers can be remarkably enhanced, and therefore the working performance of the quantum dot light-emitting diode device is effectively improved.

Drawings

In order to more clearly illustrate the technical solutions in the embodiments or the conventional technologies of the present application, the drawings used in the descriptions of the embodiments or the conventional technologies will be briefly introduced below, it is obvious that the drawings in the following descriptions are only some embodiments of the present application, and for those skilled in the art, other drawings can be obtained according to the drawings without creative efforts.

Fig. 1 is a schematic structural diagram of a quantum dot light emitting diode device according to an embodiment of the present application;

fig. 2 is a schematic structural diagram of a quantum dot light emitting diode device in another embodiment of the present application;

fig. 3 is a schematic structural diagram of a quantum dot light emitting diode device in another embodiment of the present application;

fig. 4 is a schematic structural diagram of a quantum dot light-emitting diode device in another embodiment;

fig. 5 is a schematic flow chart of a method for manufacturing a quantum dot light emitting diode device according to an embodiment of the present application. Element number description:

substrate: 100, respectively; a cathode layer: 101, a first electrode and a second electrode; light-emitting layer: 102, and (b); anode layer: 103; silver nanowire thin film: 104; the quantum dot light-emitting layer: 1021; electron transport layer: 1022; hole transport layer: 1023

Detailed Description

To facilitate an understanding of the present application, the present application will now be described more fully with reference to the accompanying drawings. Preferred embodiments of the present application are illustrated in the accompanying drawings. This application 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.

Unless defined otherwise, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this application belongs. The terminology used herein in the description of the present application is for the purpose of describing particular embodiments only and is not intended to be limiting of the application.

It will be understood that when an element is referred to as being "secured to" another element, it can be directly on the other element or intervening elements may also be present. When an element is referred to as being "connected" to another element, it can be directly connected to the other element or intervening elements may also be present. The terms "vertical," "horizontal," "left," "right," and the like as used herein are for illustrative purposes only.

In the drawings, the size of layers and regions may be exaggerated for clarity. It will be understood that when a layer or element is referred to as being "on" another layer or substrate, it can be directly on the other layer or substrate, or intervening layers may also be present. In addition, it will also be understood that when a layer is referred to as being "between" two layers, it can be the only layer between the two layers, or one or more intervening layers may also be present. Like reference numerals refer to like elements throughout.

In the following embodiments, when layers, regions or elements are "connected", it may be interpreted that the layers, regions or elements are not only directly connected but also connected through other constituent elements interposed therebetween. For example, when layers, regions, elements, etc. are described as being connected or electrically connected, the layers, regions, elements, etc. may be connected or electrically connected not only directly or directly but also through another layer, region, element, etc. interposed therebetween.

Hereinafter, although terms such as "first", "second", and the like may be used to describe various components, the components are not necessarily limited to the above terms. The above terms are only used to distinguish one component from another. It will also be understood that expressions used in the singular include expressions of the plural unless the singular has a distinctly different meaning in the context.

When a statement such as "at least one (or" an) of … … is placed after a list of elements (elements), the entire list of elements (elements) is modified rather than modifying individual elements (elements) in the list. As used herein, the term "and/or" includes any and all combinations of one or more of the associated listed items. As used herein, the term "and/or" includes any and all combinations of one or more of the associated listed items. It will be further understood that the terms "comprises/comprising," "includes" or "including," etc., specify the presence of stated features, integers, steps, operations, components, parts, or combinations thereof, but do not preclude the presence or addition of one or more other features, integers, steps, operations, components, parts, or combinations thereof.

Fig. 1 is a schematic structural diagram of a quantum dot light emitting diode device according to an embodiment, and as shown in fig. 1, the quantum dot light emitting diode device includes a substrate 100, a cathode layer 101, a light emitting layer 102, and an anode layer 103, which are sequentially stacked, where the light emitting layer 102 includes multiple layers, and each light emitting layer 102 is stacked, and a silver nanowire thin film 104 is formed between adjacent light emitting layers 102.

It is to be understood that the specific material of the substrate 100 is not particularly limited, and any known semiconductor substrate 100 material in the art may be used, for example, glass, quartz, plastic, or resin. In some embodiments of the present invention, the material of the substrate 100 may be glass, quartz, plastic, or resin. Thus, the substrate 100 made of the above material has a flat surface and corrosion resistance, and can provide a supporting function for the organic light emitting diode device. The specific thickness of the substrate 100 is not particularly limited as long as the thickness of the substrate 100 is sufficient to support the organic light emitting diode device, and may be selected by those skilled in the art according to actual needs.

The cathode layer 101 is disposed on the substrate 100 for efficiently injecting electrons into the light emitting layer 102. The cathode layer 101 may be made of a material with a low work function, which can reduce difficulty in electron injection and can also reduce heat generated during operation of the quantum dot light emitting diode, so as to improve device lifetime, where the cathode layer 101 may be made of a metal simple substance material or an alloy material, and in one embodiment, the cathode layer 101 may be an Indium Tin Oxide (ITO) material.

The light emitting layer 102 is disposed on the cathode layer 101. The light-emitting layer 102 has a light-emitting property, and also has a hole-transporting property and an electron-transporting property. The light-emitting layer 102 is used to convert an electrical signal into an optical signal, and those skilled in the art can select the material of the light-emitting layer 102 according to the specific use requirement of the organic light-emitting diode device, for example, by changing the composition of each light-emitting layer 102, the emission of multiple light colors can be realized. In one embodiment, materials with strong fluorescence in the solid state, good electron and hole transport properties, good thermal and chemical stability, and high quantum efficiency can be selected.

The number of the light emitting layers 102 includes multiple layers, for example, two or more layers, and the light emitting layers 102 are stacked, so that the current efficiency and the external quantum efficiency of the quantum dot light emitting diode device can be improved, the working performance of the quantum dot light emitting diode device can be improved, higher brightness can be realized at lower current density, and the improvement of the service life of quantum dot light emitting diode devices (QLEDs) is facilitated. And a silver nanowire film 104 is formed between the adjacent light emitting layers 102, and has excellent conductivity and light transmittance, so that the carrier generation capacity of the connecting layer can be remarkably enhanced, the excellent optical transmittance is kept, the problem that the conductivity and the optical transmittance of the carrier generation layer are contradictory in the prior art is solved, and the material is an ideal connecting layer material.

The anode layer 103 is disposed on the light emitting layer 102 for efficiently injecting holes into the light emitting layer 102, and the anode layer 103 may be made of a material with a high work function, such as aluminum (Al) material, to reduce the difficulty of hole injection.

The quantum dot light-emitting diode device comprises a substrate 100, a cathode layer 101, a light-emitting layer 102 and an anode layer 103 which are sequentially stacked, wherein the light-emitting layer 102 is a plurality of layers, each light-emitting layer 102 is stacked, a silver nanowire film 104 is formed between adjacent light-emitting layers 102, the silver nanowire film 104 is used as an intermediate connecting layer of the adjacent light-emitting layers 102, the silver nanowire film has excellent conductivity and light transmittance, the carrier generation capacity of the connecting layer can be remarkably enhanced, and therefore the working performance of the quantum dot light-emitting diode device is effectively improved.

In one embodiment, light emitting layer 102 may include quantum dot light emitting layer 10211102.

The light emitting layer 102 may be made of cadmium sulfide-zinc sulfide (CdS @ ZnS) alloy, and may have a thickness of 40 nm.

In one embodiment, the light emitting layer 102 may further include an electron transport layer 1022 formed on a side of the quantum dot light emitting layer 10211102 adjacent to the cathode layer 101, as shown in fig. 2.

An electron transport layer 1022 is formed between the cathode layer 101 and the quantum dot light emitting layer 10211102 or between the silver nanowires and the quantum dot light emitting layer 10211102, thereby increasing the injection rate of electrons in the quantum dot light emitting layer 10211102, and in one embodiment, a zinc oxide (ZnO) material may be selected as the electron transport layer 1022, and the thickness may be 50 nm.

In one embodiment, the light emitting layer 102 may further include a hole transport layer 1023 formed on a side of the quantum dot light emitting layer 10211102 away from the cathode layer 101. As shown in fig. 3.

It can be understood that the hole transport layer 1023 is formed between the quantum dot light emitting layer 10211102 and the silver nanowire, thereby increasing the injection rate of holes in the quantum dot light emitting layer 10211102.

In one embodiment, the light emitting layer 102 further includes a hole injection layer formed on the side of the hole transport layer 1023 away from the quantum dot light emitting layer 10211102. As shown in fig. 4.

It is understood that a hole injection layer is formed between the hole transport layer 1023 and the silver nanowire thin film 104 to reduce a barrier for injecting holes from the anode layer 103, so that holes can be efficiently injected from the anode layer 103 into the organic light emitting layer 102, wherein the material of the hole injection layer should be selected to have a material energy level matched with that of the anode layer 103.

In one embodiment, the hole injection layer may employ a PEDOT: PSS compound, which may have a thickness of 30 nm. And isopropanol can be added into the PEDOT PSS compound, so that the yield of PEDOT: the wettability of PSS on the hole transport layer 1023.

The embodiment of the invention also provides a preparation method of the quantum dot light-emitting diode device, which comprises the steps S110 to S140.

In step S110, a substrate 100 is provided.

Step S120, depositing a cathode layer 101 on the substrate 100.

It is understood that the cathode layer 101 is disposed on the substrate 100 for efficiently injecting electrons into the light emitting layer 102. The cathode layer 101 may be made of a material with a low work function, which can reduce difficulty in electron injection and can also reduce heat generated by the quantum dot light emitting diode during operation, thereby improving the device lifetime, wherein the cathode layer 101 may be made of a metal simple substance material or an alloy material.

Step S130, a spin coating process is used to prepare a multi-layer light emitting layer 102 on the cathode layer 101, wherein a silver nanowire film 104 is spin coated on the current light emitting layer 102 before the current light emitting layer 102 is prepared and before the next light emitting layer 102 is prepared, so that the silver nanowire film 104 is formed between adjacent light emitting layers 102.

It is understood that the light emitting layer 102 is disposed on the cathode layer 101. The light-emitting layer 102 has a light-emitting property, and also has a hole-transporting property and an electron-transporting property. The light-emitting layer 102 is used to convert an electrical signal into an optical signal, and those skilled in the art can select the material of the light-emitting layer 102 according to the specific use requirement of the organic light-emitting diode device, for example, by changing the composition of each light-emitting layer 102, the emission of multiple light colors can be realized. In one embodiment, materials with strong fluorescence in the solid state, good electron and hole transport properties, good thermal and chemical stability, and high quantum efficiency can be selected.

The silver nanowire film 104 is prepared by adopting a spin coating process, and is annealed for 10min at 80 ℃, and the thickness of the film is between 2nm and 20 nm.

In step S140, an evaporation process is used to deposit the anode layer 103 on the finally prepared light emitting layer 102.

According to the embodiment of the invention, the cathode layer 101 is deposited on the substrate 100, then the multilayer light-emitting layer 102 is prepared on the cathode layer 101 by adopting a spin coating process, wherein the silver nanowire film 104 is spin-coated on the current light-emitting layer 102 before the preparation of the next light-emitting layer 102 is completed and the preparation of the next light-emitting layer 102 is started, so that the silver nanowire film 104 is formed between the adjacent light-emitting layers 102, and finally the anode layer 103 is deposited on the finally prepared light-emitting layer 102 by adopting an evaporation process, so that the quantum dot light-emitting diode device with better working performance is obtained.

In one embodiment, fabricating the multilayer light emitting layer 102 on the cathode layer 101 includes fabricating the multilayer quantum dot light emitting layer 10211102 on the cathode layer 101.

In one embodiment, after depositing cathode layer 101 and before preparing each layer of quantum dot light emitting layer 10211102, the method further includes spin coating electron transport layer 1022 on a side of each layer of quantum dot light emitting layer 10211102 adjacent to cathode layer 101.

It can be appreciated that an electron transport layer 1022 is formed between the cathode layer 101 and the quantum dot light emitting layer 10211102 or between the silver nanowires and the quantum dot light emitting layer 10211102, thereby increasing the injection rate of electrons into the quantum dot light emitting layer 10211102, and in one embodiment, a zinc oxide (ZnO) material may be selected as the electron transport layer 1022, and the thickness may be 50 nm.

Specifically, first, the substrate 100 deposited with Indium Tin Oxide (ITO) is cleaned with a cleaning agent, deionized water, acetone, and isopropyl alcohol in sequence; drying the liquid on the surface of the substrate 100 by using nitrogen, and performing ultraviolet ozone treatment for 30 minutes to increase the wettability of zinc oxide (ZnO) on the surface of the substrate 100; then, the substrate was transferred into a glove box filled with nitrogen, a 50nm electron transport layer 1022ZnO was deposited on the ITO substrate 100 by spin coating, and then the substrate was heat-treated at 130 ℃ for 15 min.

In one embodiment, after preparing each layer of quantum dot light emitting layer 10211102, and before spin-coating silver nanowire thin film 104, the method further comprises spin-coating hole transport layer 1023 on a side of each layer of quantum dot light emitting layer 10211102 away from cathode layer 101.

It can be understood that the hole transport layer 1023 is formed between the quantum dot light emitting layer 10211102 and the silver nanowire, thereby increasing the injection rate of holes in the quantum dot light emitting layer 10211102. The hole transport layer 1023 is prepared by a spin coating process, the thickness of the hole transport layer is 50nm, and annealing is carried out at 80 ℃ for 10 min.

In one embodiment, after spin coating hole transport layer 1023, the method further includes spin coating a hole injection layer on the side of hole transport layer 1023 away from quantum dot light emitting layer 10211102.

It should be understood that, although the steps in the flowcharts of the figures are shown in order as indicated by the arrows, the steps are not necessarily performed in order as indicated by the arrows. The steps are not performed in the exact order shown and described, and may be performed in other orders, unless explicitly stated otherwise. Moreover, at least some of the steps in the figures may include multiple steps or multiple stages, which are not necessarily performed at the same time, but may be performed at different times, which are not necessarily performed in sequence, but may be performed alternately or at least partially in sequence with other steps or other steps.

An embodiment of the present invention further provides a display panel, including the quantum dot light emitting diode device according to any one of the above embodiments.

Specifically, the display panel may include a plurality of pixel units, and at least one organic light emitting diode device in the above embodiment is disposed in each pixel unit.

The display panel further comprises a polarizer and/or a touch layer group which are stacked on the diode device. Specifically, the polarizer and the touch layer group are arranged on the first side of the diode device in a laminating mode through the bonding layer. It should be noted that the stacking order of the polarizer and the opposing diode devices of the touch layer group may be determined according to specific situations, and is not limited herein.

It is understood that the polarizer and the touch layer are well known to those skilled in the art and are not important in the present application, and therefore, the detailed structure and principle thereof will not be described herein.

Based on the same inventive concept, embodiments of the present application further provide a display device (not shown), which includes the display panel in the above embodiments.

It can be understood that the display device in the embodiment of the present application may be any product or component having a display function, such as a QLED display device, electronic paper, a mobile phone, a tablet computer, a television, a display, a notebook computer, a digital photo frame, a navigator, a wearable device, and an internet of things device, and the embodiment disclosed in the present application is not limited thereto.

Electronic or electrical devices and/or any other related devices or components (e.g., display devices including display panels and display panel drivers, wherein the display panel drivers also include driver controllers, gate drivers, gamma reference voltage generators, data drivers, and emission drivers) according to embodiments of the inventive concepts described herein may be implemented using any suitable hardware, firmware (e.g., application specific integrated circuits), software, or a combination of software, firmware, and hardware. For example, various components of these devices may be formed on one Integrated Circuit (IC) chip or on separate IC chips. In addition, various components of these devices may be implemented on a flexible printed circuit film, a Tape Carrier Package (TCP), a Printed Circuit Board (PCB), or formed on one substrate 100. In addition, various components of these devices may be processes or threads that execute on one or more processors in one or more computing devices, thereby executing computer program instructions and interacting with other system components to perform the various functions described herein. Moreover, those skilled in the art will recognize that the functions of the various computing devices may be combined or integrated into a single computing device, or that the functions of a particular computing device may be distributed across one or more other computing devices, without departing from the spirit and scope of the exemplary embodiments of the present concepts.

Although exemplary embodiments of a display panel and a display apparatus including the same have been particularly described herein, many modifications and variations will be apparent to those skilled in the art. Accordingly, it will be understood that display panels and display devices including display panels constructed in accordance with the principles of the present application may be implemented other than as specifically described herein. The application is also defined in the claims and their equivalents.

In the description herein, references to the description of "some embodiments," "other embodiments," "desired embodiments," etc., mean that a particular feature, structure, material, or characteristic described in connection with the embodiment or example is included in at least one embodiment or example of the invention. In this specification, a schematic description of the above terminology may not necessarily refer to the same embodiment or example.

The technical features of the embodiments described above may be arbitrarily combined, and for the sake of brevity, all possible combinations of the technical features in the embodiments described above are not described, but should be considered as being within the scope of the present specification as long as there is no contradiction between the combinations of the technical features.

The above-mentioned embodiments only express several embodiments of the present application, and the description thereof is more specific and detailed, but not construed as limiting the scope of the invention. It should be noted that, for a person skilled in the art, several variations and modifications can be made without departing from the concept of the present application, which falls within the scope of protection of the present application. Therefore, the protection scope of the present patent shall be subject to the appended claims.

Claims

1. A quantum dot light-emitting diode device, characterized in that it comprises a substrate, a cathode layer, a light-emitting layer and an anode layer that are stacked successively, wherein the light-emitting layer comprises multiple layers, and each of the light-emitting layers is stacked and arranged adjacent to one another. A silver nanowire thin film is formed between the light-emitting layers.

2 . The quantum dot light emitting diode device according to claim 1 , wherein the light emitting layer comprises a quantum dot light emitting layer. 3 .

3 . The quantum dot light emitting diode device according to claim 2 , wherein the light emitting layer further comprises an electron transport layer formed on the side of the quantum dot light emitting layer close to the cathode layer. 4 .

4 . The quantum dot light-emitting diode device according to claim 2 , wherein the light-emitting layer further comprises a hole transport layer formed on a side of the quantum dot light-emitting layer away from the cathode layer. 5 .

5 . The quantum dot light emitting diode device according to claim 4 , wherein the light emitting layer further comprises a hole injection layer formed on a side of the hole transport layer away from the quantum dot light emitting layer. 6 .

6. A method for preparing a quantum dot light-emitting diode device, comprising:

provide a substrate;

depositing a cathode layer on the substrate;

A multi-layer light-emitting layer is prepared on the cathode layer by a spin-coating process, wherein a silver nanowire thin film is spin-coated on the current light-emitting layer before the preparation of the current light-emitting layer is completed and before the preparation of the next light-emitting layer starts, so that the silver nanowire thin film is formed between the adjacent light-emitting layers;

An anode layer is deposited on the finally prepared light-emitting layer by an evaporation process.

7 . The method for preparing a quantum dot light-emitting diode device according to claim 6 , wherein the preparing a multi-layer light-emitting layer on the cathode layer comprises: 8 .

A multilayer quantum dot light-emitting layer is prepared on the cathode layer.

8 . The method for preparing a quantum dot light-emitting diode device according to claim 7 , wherein after depositing the cathode layer and before preparing each layer of the quantum dot light-emitting layer, the method further comprises: 9 .

An electron transport layer is spin-coated on the side of each layer of the quantum dot light-emitting layer close to the cathode layer.

9 . The method for preparing a quantum dot light-emitting diode device according to claim 6 , wherein after preparing each layer of the quantum dot light-emitting layer and before spin-coating the silver nanowire thin film, the method further comprises: 10 .

spin-coating a hole transport layer on the side of each layer of the quantum dot light-emitting layer away from the cathode layer;

A hole injection layer is spin-coated on the side of the hole transport layer away from the quantum dot light-emitting layer.

10. A display panel, comprising the quantum dot light emitting diode device according to any one of claims 1 to 5.