Novel hole generation structure-based electroluminescent device and preparation method thereof

Abstract

The invention provides an electroluminescent device based on a novel hole generation structure and a preparation method, belongs to the technical field of display illumination, and aims to improve the luminescence performance of the electroluminescent device and reduce the turn-on voltage. The electroluminescent device comprises a transparent substrate, and a first insulating layer, a novel hole generation layer, a hole transport layer, a luminescent layer, an electron generation layer, a second insulating layer and a metal electrode which are sequentially located on one side of the transparent substrate, wherein the novel hole generation layer comprises a nano-particle material and a hole generation material, and the doping concentration of the nano-particle material in the hole generation material is 1%-80%. Therefore, the invention provides a novel hole generation structure as the hole generation layer, and more hole carriers can be efficiently provided because the conductivity is higher and the energy level is deeper. Therefore, the turn-on voltage of the electroluminescent device can be reduced, the luminescence performance can be improved, and the overall energy consumption can be reduced.

Description

Technical Field

[0001] The present application relates to the field of lighting display technology, and in particular to an electroluminescent device based on a novel hole generating structure and a preparation method thereof. Background Art

[0002] In the field of modern electronic devices, field-effect light emitting devices (FELDs) are an important photoelectric conversion tool and are widely used in display technology, sensors, optical communications and other fields. These devices achieve periodic light output by relying on the periodic oscillation of intrinsic carriers inside the material under the action of an external driving electric field. Compared with traditional light-emitting diodes (LEDs), FELDs have the advantages of fast response speed, low power consumption, and high integration. FELDs have a simple structure and are easy to integrate into microelectronic circuits, making them suitable for micro- and nano-scale optoelectronic devices.

[0003] One of the keys to FELDs performance is to effectively enhance the recombination efficiency of electrons and holes to improve the luminescence efficiency and overall performance of the device. However, current EL devices face some challenges, one of which is the generation and transport efficiency of holes. The device structure of traditional EL devices leads to low efficiency of hole generation, and a large number of holes are lost in the transport within the device, thus limiting the quantum efficiency and luminescence brightness of the device. Summary of the invention

[0004] In view of the above problems existing in the prior art, the present invention provides an electroluminescent device and method based on a novel hole generation structure to solve the problem that the hole generation efficiency of the current electroluminescent device is low, resulting in its poor performance.

[0005] In a first aspect of the present invention, there is provided an electroluminescent device based on a novel hole generating structure, the electroluminescent device comprising: a transparent substrate, and the following components located on one side of the transparent substrate:

[0006] A first insulating layer, a novel hole generating layer, a hole transporting layer, a light emitting layer, an electron generating layer, a second insulating layer and a metal electrode;

[0007] The novel hole generating layer comprises nano-particle material and hole generating material, and the doping concentration of the nano-particle material in the hole generating material is 1%-80%.

[0008] Furthermore, the nanoparticle material is MoO3 nanomaterial, MoS2 nanomaterial, NiO x Any of the nanomaterials and WS2.

[0009] Furthermore, the hole transport layer is made of any one of PVK, HAT-CN, TFB and PF8CZ.

[0010] Furthermore, the constituent materials of the light-emitting layer include any one of CdSe / ZnS quantum dots, CdSe / ZnSe quantum dots, InP / ZnS quantum dots and ZnSe / ZnS quantum dots, and any one of organic light-emitting materials and perovskite light-emitting materials.

[0011] Furthermore, the constituent materials of the electron generation layer include any one of ZnMgO, PEDOT:PSS, ZnO, ZnSnO, B4PYMPM, B3PYMPM, BmPYPB, TmPYPB, TPBi, Bphen, and any one of MXENE, PCBM, 3TPYMB.

[0012] Further, the composition material of the insulating layer includes any one of PVDF, P(VDF-TRFE-CFE), LiF, HfO2, PMMA, and PVDF-HFP;

[0013] Wherein, the insulating layer includes the first insulating layer and / or the second insulating layer.

[0014] Furthermore, the transparent substrate is a hard substrate or a flexible substrate; wherein the constituent material of the hard substrate includes any one of glass, silicon dioxide or quartz, and the constituent material of the flexible substrate includes polyethylene terephthalate, polyethylene naphthalate or polyimide.

[0015] The second aspect of the present invention provides a method for preparing an electroluminescent device based on a novel hole generating structure, the method being applied to the electroluminescent device based on a novel hole generating structure provided in the first aspect of the present invention, the method comprising:

[0016] Step 1, cleaning the transparent substrate, and coating the surface of the cleaned transparent substrate with an insulating material to sequentially form a first insulating layer;

[0017] Step 2, coating the mixed solution on the transparent substrate obtained in step 1 to form a novel hole generating layer; wherein the mixed solution is obtained by mixing a nanoparticle material and a hole generating material, and the doping concentration of the nanoparticle material in the hole generating material is 1%-80%;

[0018] Step 3, coating a hole transport material, a luminescent material, an electron generating material and an insulating material on the novel hole generating layer obtained in step 2 in sequence to form a hole transport layer, a luminescent layer, an electron generating layer and a second insulating layer in sequence;

[0019] Step 4, evaporating a metal electrode on the transparent substrate obtained in step 3 to obtain the electroluminescent device based on the novel hole generating structure.

[0020] Furthermore, in step 2, the step of preparing the mixed solution comprises:

[0021] Step 2-1, dissolving the hole generating material and the nanoparticle material into a solvent respectively to obtain a first solution and a second solution;

[0022] Step 2-2, doping the second solution into the first solution at a concentration ratio of 1%-80% to obtain the mixed solution.

[0023] Furthermore, in step 1, the cleaning of the transparent substrate comprises:

[0024] Step 1-1, ultrasonically cleaning the transparent substrate using an ultrasonic cleaning apparatus containing a washing solution, deionized water and anhydrous ethanol;

[0025] Step 1-2, performing nitrogen drying treatment on the transparent substrate after the ultrasonic cleaning to remove organic matter and dust on the transparent substrate.

[0026] The electroluminescent device based on the novel hole generating structure provided by the present invention comprises a transparent substrate, and a first insulating layer, a novel hole generating layer, a hole transport layer, a light emitting layer, an electron generating layer, a second insulating layer and a metal electrode which are sequentially arranged on the surface of one side of the transparent substrate; wherein the novel hole generating layer comprises nano-particle material and hole generating material, and the doping concentration of the nano-particle material in the hole generating material is 1%-80%.

[0027] Therefore, the present invention dopes nanoparticle materials into the hole generating material for preparing the hole generating layer. Due to the doping of the nanoparticle materials, the hole mobility of the hole generating material is greatly improved and its HOMO energy level is reduced, which makes it easier for holes to migrate from the hole generating layer to the hole transport material; thereby, the hole concentration in the light-emitting layer is greatly increased, the large injection barrier between the hole generating layer and the hole transport layer is alleviated, and it is helpful to balance the concentration of electrons and holes injected into the light-emitting layer, thereby improving the carrier recombination efficiency of electrons and holes in the light-emitting layer, so that the luminescence efficiency of the field light-emitting device is significantly improved. BRIEF DESCRIPTION OF THE DRAWINGS

[0028] In order to more clearly illustrate the technical solution of the present application, the drawings required for use in the description 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 A schematic structural diagram of an electroluminescent device based on a novel hole generating structure provided by an embodiment of the present invention is shown;

[0030] Figure 2 A flow chart showing the steps of a method for preparing an electroluminescent device based on a novel hole generating structure provided by an embodiment of the present invention;

[0031] Figure 3 The graph shows the change curve of the luminous brightness of the electroluminescent devices of Example 1 and Comparative Example 1 with the change of the alternating voltage under the same driving electric field.

[0032] Description of reference numerals:

[0033] 1. Transparent substrate; 2. First insulating layer; 3. New hole generating layer; 4. Hole transport layer; 5. Light-emitting layer; 6. Electron generating layer; 7. Second insulating layer; 8. Metal electrode. DETAILED DESCRIPTION

[0034] 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.

[0035] It needs to be explained that field-induced light-emitting devices (FELDs), quantum dot light-emitting diodes (QLEDs) and organic light-emitting diodes (OLEDs) are three different types of light-emitting technologies, which differ in materials, light-emitting principles, manufacturing processes and applications. Field-induced light-emitting devices, as a non-injection device driven by an electric field, do not require external carrier injection devices, but rely on the periodic oscillation of intrinsic carriers generated by the internal electric field of the material to achieve periodic light output. As DC injection devices, QLED and OLED rely on the direct injection and recombination of holes and electrons for light emission. By applying an external electric field, electrons and holes are directly injected into the light-emitting layer from different electrodes, and then recombine in the light-emitting layer to emit light.

[0036] Therefore, FELDs rely on high-intensity electric fields to excite electrons and holes in the material, and do not rely on external injection of electrons and holes. Therefore, they are different from electroluminescent devices such as OLED or QLED that strongly rely on hole injection and recombination. Since the hole generation characteristics of FELDs are different from the hole injection characteristics of OLED or QLED, the carrier concentration inside them is much lower than that of traditional DC injection devices, which leads to poor device performance of field-induced light-emitting devices. In addition, traditional DC injection devices consider the energy level matching and conductivity performance during the injection process to enhance the injection efficiency of holes, which cannot be applied to the needs of FELDs for non-injection devices. As a result, FELDs are still in a relatively early stage of research and development, with low technical maturity, and their commercial applications are far lower than OLED or QLED.

[0037] In view of this, the present invention provides a novel hole generating structure for improving the performance of an electroluminescent device, in which nanoparticle materials are doped in a traditional hole generating layer. Due to the doping of the nanoparticle materials, the hole mobility of the hole generating material is greatly improved, and its HOMO energy level is reduced, which makes it easier for holes to migrate from the hole generating layer to the hole transport material; thereby, the hole concentration in the light-emitting layer 5 is greatly increased, the large injection barrier between the hole generating layer and the hole transport layer 4 is alleviated, and it is helpful to balance the concentration of electrons and holes injected into the light-emitting layer 5, thereby improving the carrier recombination efficiency of electrons and holes in the light-emitting layer 5, so that the luminescence efficiency of the electroluminescent device is significantly improved.

[0038] The present invention will be described in detail below with reference to the accompanying drawings and in conjunction with embodiments.

[0039] In a first aspect of the embodiment of the present invention, referring to Figure 1 , Figure 1 FIG. 1 shows a schematic diagram of the structure of an electroluminescent device based on a novel hole generating structure provided by an embodiment of the present invention. Figure 1 As shown, including:

[0040] A transparent substrate 1, and a first insulating layer 2, a novel hole generating layer 3, a hole transport layer 4, a light emitting layer 5, an electron generating layer 6, a second insulating layer 7 and a metal electrode 8 are sequentially arranged on the surface of one side of the transparent substrate 1; wherein the hole generating layer 3 comprises nanoparticle material and hole generating material, and the doping concentration of the nanoparticle material in the hole generating material is 1%-80%.

[0041] In this embodiment, in FELDs, the hole generation layer generates holes by exciting the internal materials of the device under the action of the electric field, rather than introducing carriers from the outside, and therefore relies on the electric field responsiveness of the preparation material of the hole generation layer. Among them, the hole generation material has excellent electric field response characteristics and can effectively generate holes under high electric fields, while the nanoparticle material can enhance the hole generation efficiency under the action of the electric field, and overall enhance the electric field induced hole generation.

[0042] Specifically, in the embodiment of the present invention, nanoparticle materials are doped into the hole generating material, and the nanoparticle materials will form agglomerations with the hole generating material to form a shape similar to a core-shell structure, so that the hole mobility of the hole generating layer 3 is improved and its HOMO energy level is reduced, which makes it easier for holes to be injected from the hole generating layer 3 into the hole transport layer 4. As a result, the hole concentration in the light-emitting layer 5 is greatly increased, and the large injection barrier between the hole generating layer 3 and the hole transport layer 4 is alleviated, which helps to balance the concentration of electrons and holes injected into the light-emitting layer 5, thereby improving the carrier recombination efficiency of electrons and holes in the light-emitting layer 5, avoiding the situation where the holes and electrons undergo Auger recombination due to the imbalance of the concentration of holes and electrons, so that the luminous efficiency of the field light-emitting device is significantly improved.

[0043] Among them, the nanoparticle material is preferably metal oxide nanoparticles and metal sulfide nanoparticles.

[0044] As a specific explanation of the present embodiment, the doped metal oxide and metal sulfide are nano-metal particles, and the size of the nano-particles is generally in the range of 1-100 nanometers. Due to their small size but large specific surface area and surface energy, the nano-particle material and the hole generating material are easily attracted to each other and contact more under specific conditions, and spontaneously form an agglomerate structure. However, non-nanoparticles, such as micron particles or coarse particles, are difficult to form a tight core-shell agglomerate structure in the hole generating material because the particles are large but the specific surface area is small. The agglomerate structure generated by the doped nano-particle material of the embodiment of the present invention effectively improves the hole mobility of the hole generating layer.

[0045] The agglomerated structure is specifically that the hole generating material is coated with a plurality of nano-particle materials.

[0046] Specifically, the hole generating material can be any one of PEDOT:PSS, TAPC and TCTA. The nanoparticle material can be a Mo-based nanoparticle material or other metal-based nanoparticle material, specifically MoO3 nanomaterial, MoS2 nanomaterial, NiO x Any of the nanomaterials and WS2.

[0047] For example, the doping concentration of the nanoparticle material in the hole generating material may be 1%;

[0048] The doping concentration of the nanoparticle material in the hole generating material may be 30%;

[0049] The doping concentration of the nanoparticle material in the hole generating material may be 50%;

[0050] The doping concentration of the nanoparticle material in the hole generating material may be 70%;

[0051] The doping concentration of the nanoparticle material in the hole generating material may be 80%.

[0052] Exemplarily, the present invention selects MoO3 nanomaterial as nanoparticle material, selects PEDOT:PSS as hole generating material, and obtains PEDOT:PSS-MoO3 agglomerates; or selects MoS2 nanomaterial as nanoparticle material, selects PEDOT:PSS as hole generating material, and obtains PEDOT:PSS-MoS2 agglomerates; or selects NiO x Nanomaterials are used as nanoparticle materials, TAPC is selected as the hole generating material, and TAPC-NiO is obtained. x Therefore, the novel hole generating layer 3 provided in the embodiment of the present invention is suitable for enhancing the generation of holes in a non-injection type device under an electric field, and is applied to a non-injection type light-emitting device to enhance its hole generating ability.

[0053] The electroluminescent device based on the novel hole generating structure provided in the embodiment of the present invention, by doping the hole generating material for preparing the hole generating layer 3 with a nano-particle material having a concentration of 1%-80%, the concentration of holes in the hole generating layer 3 is increased by the doped nano-particle material, thereby increasing the mobility of holes, and reducing the injection barrier with the hole transport layer 4, so that the concentrations of electrons and holes migrated to the light-emitting layer 5 tend to be balanced, thus reducing the situation where the electrons and holes cannot emit light due to Auger recombination, thereby increasing the luminescence efficiency of the electroluminescent device and improving its device performance.

[0054] It is understandable that the doping concentration of the nanoparticle material in the hole generating material should not be too high or too low. When the doping concentration of the nanoparticle material is low, the agglomeration formed between it and the hole generating material is limited, and the influence on the carrier mobility and energy level is not great, the hole concentration is limited, and the hole generating efficiency is still low. If the doping concentration of the nanoparticle material is too high, the morphology of the hole generating layer 3 will become rough, and the proportion of the hole generating material is too low, resulting in too much nanoparticle material wrapped outside in the agglomerate, reducing its hole mobility. On the contrary, it will reduce the luminous efficiency of the electroluminescent device and fail to improve the performance of the electroluminescent device.

[0055] The energy levels of the hole generating material and the hole transporting material are matched to achieve the migration of holes from the hole generating layer 3 to the hole transporting layer 4 .

[0056] The material for preparing the light-emitting layer 5 can be selected from quantum dot light-emitting materials, organic light-emitting materials, and perovskite light-emitting materials, and specifically can be any one of CdSe / ZnS quantum dots, CdSe / ZnSe quantum dots, TDBA-AC, and CsPbBr3.

[0057] It is understandable that the light-emitting layer 5 may include only one layer or multiple layers, depending on the purpose of the device. If the light-emitting layer 5 includes multiple layers, the light-emitting materials of the multiple layers of the light-emitting layer 5 may be the same or different.

[0058] In one embodiment, when the doping concentration of the nanoparticle material in the hole generating material is 30%, the luminescence efficiency of the device is relatively high, which has a more obvious effect on improving the performance of the device. Therefore, in a specific implementation, the nanoparticle material with a doping ratio of 30% can be mixed with the hole generating material to improve the luminescence efficiency of the device.

[0059] Among them, the transparent substrate 1 can be a hard substrate or a flexible substrate, the only difference is whether the device as a whole is flexible or hard; when the transparent substrate 1 is a hard substrate, it can include any one of glass, silicon dioxide or quartz; when the transparent substrate 1 is a flexible substrate, it can include polyethylene terephthalate, polyethylene naphthalate or polyimide.

[0060] The electroluminescent device based on the novel hole generation structure provided by the embodiment of the present invention is doped with nanoparticle material with a concentration of 1%-80% in the hole generation material for preparing the hole generation layer 3. The doped nanoparticle material can increase the concentration of holes in the hole generation layer 3, thereby increasing the mobility of holes and reducing the injection barrier with the hole transport layer 4, so that the concentrations of electrons and holes injected into the light-emitting layer 5 tend to be balanced. In this way, the situation where the electrons and holes cannot emit light due to Auger recombination can be reduced, the luminous efficiency of the electroluminescent device is improved, and the performance of the device is improved.

[0061] In a second aspect of the embodiment of the present invention, referring to Figure 2 , Figure 2 The schematic diagram of the steps of the method for preparing an electroluminescent device based on a novel hole generating structure provided by an embodiment of the present invention is shown as follows: Figure 2 As shown, the preparation method specifically comprises:

[0062] In step S101 , the transparent substrate 1 is cleaned, and an insulating material is coated on the surface of the cleaned transparent substrate 1 to sequentially form a first insulating layer 2 .

[0063] Specifically, after the transparent substrate 1 is cleaned, the preparation process of the electroluminescent device is carried out to reduce the interference of impurities in the preparation process. According to the structure of the electroluminescent device, each layer is prepared in sequence from the transparent substrate 1 to the metal electrode 8. After the transparent substrate 1 is cleaned, an insulating material is first spin-coated on the transparent substrate 1, and after the spin-coating, the transparent substrate 1 is placed on a heating platform for annealing to form a first insulating layer 2 on the transparent substrate 1.

[0064] Among them, the insulating material can be any one of PVDF, P (VDF-TRFE-CFE), LiF, HfO2, PMMA, and PVDF-HFP.

[0065] Step S102, coating a mixed solution on the transparent substrate 1 obtained in step 101 to form a novel hole generating layer 3; wherein the mixed solution is obtained by mixing a nanoparticle material and a hole generating material, and the doping concentration of the nanoparticle material in the hole generating material is 1%-80%.

[0066] Specifically, the doping process of the nanoparticle material is implemented before preparing the hole generating layer, firstly the hole generating material and the nanoparticle material form a mixed solution, then the mixed solution is coated on the first insulating layer 2, and after coating, the transparent substrate 1 is placed on a heating platform for annealing to form a hole generating layer on the first insulating layer 2. In this case, in the formed hole generating layer, in addition to the hole generating material, there is also some nanoparticle material. When the device emits light based on the driving electric field, the core-shell structure formed by the nanoparticle material and the hole generating material in the hole generating layer 3 increases the hole mobility of the hole generating layer and reduces the injection barrier with the hole transport layer 4, so that the concentration of the electrons and holes injected into the light-emitting layer 5 tends to be balanced, thereby improving the luminous efficiency of the device.

[0067] The hole generating material may be any one of PEDOT:PSS, TAPC and TCTA. The nanoparticle material may be a Mo-based nanoparticle material or other metal-based nanoparticle material, specifically MoO3 nanomaterial, MoS2 nanomaterial, NiO x Any of the nanomaterials and WS2.

[0068] In this embodiment, the doping concentration of the nanoparticle material in the hole generating material is 1%-80%, and the doping concentration of the nanoparticle material in the hole generating material should not be too high or too low. When the doping concentration of the nanoparticle material is low, the agglomeration formed between the nanoparticle material and the hole generating material is limited, and the influence on the carrier mobility and energy level is not great, the hole concentration is limited, and the hole generating efficiency is still low; if the doping concentration of the nanoparticle material is too high, the morphology of the hole generating layer 3 will become rough, and the proportion of the hole generating material is too low, resulting in too much nanoparticle material wrapped outside the agglomerate, reducing its hole mobility. Instead, it will reduce the luminous efficiency of the electroluminescent device and fail to improve the performance of the electroluminescent device.

[0069] For example, the doping concentration of the nanoparticle material in the hole generating material may be 1%;

[0070] The doping concentration of the nanoparticle material in the hole generating material may be 30%;

[0071] The doping concentration of the nanoparticle material in the hole generating material may be 50%;

[0072] The doping concentration of the nanoparticle material in the hole generating material may be 70%;

[0073] The doping concentration of the nanoparticle material in the hole generating material may be 80%.

[0074] Step S103, coating the hole transport material, luminescent material, electron generating material and insulating material on the novel hole generating layer 3 obtained in step 102 in sequence to form subsequent film layers (hole transport layer 4, luminescent layer 5, electron generating layer 6 and second insulating layer 7) in sequence.

[0075] Specifically, after forming a hole generating layer, a hole transport material is coated on the hole generating layer, and after coating, the transparent substrate 1 is placed on a heating platform for annealing to form a hole transport layer 4 on the hole generating layer; a luminescent material is coated on the hole transport layer 4, and after coating, the transparent substrate 1 is placed on a heating platform for annealing to form a luminescent layer 5 on the hole transport layer 4; then, an electron generating material is coated on the luminescent layer 5, and after coating, the transparent substrate 1 is placed on a heating platform for annealing to form an electron generating layer 6 on the luminescent layer 5; thereafter, an insulating material is coated on the electron generating layer 6, and after coating, the transparent substrate 1 is placed on a heating platform for annealing to form a second insulating layer 7 on the electron generating layer 6.

[0076] Among them, the luminescent material can be selected from quantum dot luminescent materials, organic luminescent materials and perovskite luminescent materials, etc., specifically any one of CdSe / ZnS quantum dots, CdSe / ZnSe quantum dots, TDBA-AC, CsPbBr3; the electron generating material can be any one of ZnO and ZnMgO, and the insulating material can be the same as or different from the insulating material of the first insulating layer 2, and specifically any one of PVDF, P (VDF-TRFE-CFE), LiF, HfO2, PMMA, PVDF-HFP.

[0077] Step S104, vapor-depositing a metal electrode 8 on the transparent substrate 1 obtained in step S103, to obtain the electroluminescent device based on the novel hole generating structure.

[0078] The metal electrode 8 may be any one of gold, silver, copper and aluminum. In a specific implementation, the metal electrode 8 is formed on the second insulating layer 7 by placing the transparent substrate 1 in a vacuum evaporation system for evaporation.

[0079] The electroluminescent QLED device based on the novel high-efficiency hole generating structure provided by the embodiment of the present invention is adopted. By doping the hole generating material of the hole generating layer with a concentration of 1%-80%, the doped nanoparticle material can increase the concentration of holes in the hole generating layer 3, thereby increasing the mobility of holes and reducing the injection barrier with the hole transport layer 4, so that the concentration of electrons and holes injected into the light-emitting layer 5 tends to be balanced. In this way, the situation where the electrons and holes cannot emit light due to Auger recombination can be reduced, the luminescence efficiency of the electroluminescent device is improved, and the device performance is improved.

[0080] In one embodiment, the preparation process of the mixed solution is specifically as follows: firstly, the hole generating material and the nanoparticle material are dissolved in the solvent respectively to obtain a first solution and a second solution; then, the second solution is doped into the first solution at a concentration ratio of 1%-80% to obtain a mixed solution.

[0081] The concentration of the hole generating material and the concentration of the nanoparticle material in the first solution and the second solution are not limited in the present invention, and the solvent can dissolve both the hole generating material and the nanoparticle material.

[0082] For example, the hole generating material and the nanoparticle material are dissolved in water and ethanol solvent at a concentration of 20 mg / ml, respectively, to obtain a first solution and a second solution, respectively; then, the second solution is doped into the first solution at a concentration ratio of 30% to obtain a mixed solution.

[0083] In the present embodiment, nanoparticle materials are selected for doping, and the size of the nanoparticles is usually in the range of 1-100 nanometers. Due to its small size but large specific surface area and surface energy, the nanoparticle materials and the hole generating materials are easily attracted to each other and contact more under specific conditions, and spontaneously form a cluster structure. Then, the nanoparticle materials are prepared first and then doped, rather than directly dissolved, so that the distribution of the nanoparticle materials and the hole generating materials is orderly and controllable rather than randomly dispersed, thereby further forming an effective cluster structure.

[0084] Therefore, in the embodiment of the present invention, nanoparticle material is doped into the hole generating material. The nanoparticle material will agglomerate with the hole generating material to form a shape similar to a core-shell structure, so that the hole mobility of the hole generating layer 3 is improved and its HOMO energy level is reduced, which makes it easier for holes to be injected from the hole generating layer 3 into the hole transport layer 4.

[0085] In one embodiment, the specific process of cleaning the transparent substrate 1 can be firstly ultrasonically cleaning the transparent substrate 1 through an ultrasonic cleaning apparatus containing a washing solution, deionized water and anhydrous ethanol; then, the transparent substrate 1 after the ultrasonic cleaning is dried with nitrogen to remove organic solvents and dust on the transparent substrate 1.

[0086] By adopting the method for preparing an electroluminescent device based on a novel hole generating structure provided in an embodiment of the present invention, the obtained electroluminescent device has nanoparticle material doped in the hole generating material of the hole generating layer. The core-shell structure formed by the nanoparticle material and the hole generating material in the hole generating layer 3 increases the hole mobility of the hole generating layer and reduces the injection barrier with the hole transport layer 4, so that the concentration of electrons and holes injected into the light-emitting layer 5 tends to be balanced, thereby improving the luminescence efficiency of the device.

[0087] In order to enable those skilled in the art to better understand the present invention, a novel hole generating structure for improving the performance of an electroluminescent device of the present invention is described below through a number of specific embodiments.

[0088] Example 1

[0089] Step 1, ultrasonically cleaning the ITO glass substrate using an ultrasonic cleaning apparatus containing a washing solution, deionized water, and anhydrous ethanol;

[0090] Step 2, performing nitrogen drying treatment on the glass substrate after ultrasonic cleaning to remove organic matter and dust on the glass substrate;

[0091] Step 3, spin coating a PVDF solution on a glass substrate, and after spin coating, placing the glass substrate on a heating platform for annealing to form a first insulating layer 2;

[0092] Step 4, dissolving PEDOT:PSS and MoO3 nanoparticles in water and ethanol solvents at a concentration of 20 mg / ml, respectively, to obtain a first solution and a second solution;

[0093] Step 5, doping the second solution into the first solution at a concentration ratio of 30% to obtain a mixed solution;

[0094] Step 6, spin coating the mixed solution on the first insulating layer 2 formed in step 3, and placing the glass substrate on a heating platform for annealing after spin coating to form a hole generating layer;

[0095] Step 7, spin coating TFB on the hole generating layer formed in step 6, and placing the glass substrate on a heating platform for annealing after spin coating to form a hole transport layer 4;

[0096] Step 8, spin coating CdSe / ZnS quantum dots on the hole transport layer 4 formed in step 7, and placing the glass substrate on a heating platform for annealing after spin coating to form a light-emitting layer 5;

[0097] Step 9, spin coating ZnMgO on the light emitting layer 5 formed in step 8, and placing the glass substrate on a heating platform for annealing after spin coating to form an electron generating layer 6;

[0098] Step 10, spin coating the PVDF solution on the electron generating layer 6 formed in step 9, and after spin coating, placing the glass substrate on a heating platform for annealing to form a second insulating layer 7;

[0099] Step 11, vapor-depositing an aluminum electrode on the second insulating layer 7 formed in step 10 to obtain an electroluminescent device based on a novel hole generating structure.

[0100] Example 2

[0101] Step 1, ultrasonically cleaning the ITO glass substrate using an ultrasonic cleaning apparatus containing a washing solution, deionized water, and anhydrous ethanol;

[0102] Step 2, performing nitrogen drying treatment on the glass substrate after ultrasonic cleaning to remove organic matter and dust on the glass substrate;

[0103] Step 3, spin coating a PVDF solution on a glass substrate, and after spin coating, placing the glass substrate on a heating platform for annealing to form a first insulating layer 2;

[0104] Step 4, dissolving PEDOT:PSS and MoO3 nanoparticles in water and ethanol solvents at a concentration of 20 mg / ml, respectively, to obtain a first solution and a second solution;

[0105] Step 5, doping the second solution into the first solution at a concentration ratio of 30% to obtain a mixed solution;

[0106] Step 6, spin coating the mixed solution on the first insulating layer 2 formed in step 3, and placing the glass substrate on a heating platform for annealing after spin coating to form a hole generating layer;

[0107] Step 7, spin coating TFB on the hole generating layer formed in step 6, and placing the glass substrate on a heating platform for annealing after spin coating to form a hole transport layer 4;

[0108] Step 8, spin coating CdSe / ZnS quantum dots on the hole transport layer 4 formed in step 7, and placing the glass substrate on a heating platform for annealing after spin coating to form a light-emitting layer 5;

[0109] Step 9, spin coating ZnMgO on the light emitting layer 5 formed in step 8, and placing the glass substrate on a heating platform for annealing after spin coating to form an electron generating layer 6;

[0110] Step 10, spin coating the PVDF solution on the electron generating layer 6 formed in step 9, and after spin coating, placing the glass substrate on a heating platform for annealing to form a second insulating layer 7;

[0111] Step 11, evaporating a silver electrode on the second insulating layer 7 formed in step 10 to obtain an electroluminescent device based on a novel hole generating structure.

[0112] Comparative Example 1

[0113] Step 1, ultrasonically cleaning the ITO glass substrate using an ultrasonic cleaning apparatus containing a washing solution, deionized water, and anhydrous ethanol;

[0114] Step 2, performing nitrogen drying treatment on the glass substrate after ultrasonic cleaning to remove organic matter and dust on the glass substrate;

[0115] Step 3, spin coating a PVDF solution on a glass substrate, and after spin coating, placing the glass substrate on a heating platform for annealing to form a first insulating layer 2;

[0116] Step 4, spin coating PEDOT:PSS on the first insulating layer 2 formed in step 3, and placing the glass substrate on a heating platform for annealing after spin coating to form a hole generating layer;

[0117] Step 5, spin coating the TFB solution on the hole generating layer formed in step 4, and after spin coating, placing the glass substrate on a heating platform for annealing to form a hole transport layer 4;

[0118] Step 6, spin coating CdSe / ZnS quantum dots on the hole transport layer 4 formed in step 5, and placing the glass substrate on a heating platform for annealing after spin coating to form a light-emitting layer 5;

[0119] Step 7, spin coating ZnMgO on the light emitting layer 5 formed in step 6, and after spin coating, placing the glass substrate on a heating platform for annealing to form an electron generating layer 6;

[0120] Step 8, spin coating the PVDF solution on the electron generating layer 6 formed in step 7, and placing the glass substrate on a heating platform for annealing after spin coating to form a second insulating layer 7;

[0121] Step 9, vapor-depositing an aluminum electrode on the second insulating layer 7 formed in step 8 to obtain an electroluminescent QLED device with a traditional structure.

[0122] The electroluminescent device based on the novel hole generating structure obtained in Example 1 and the electroluminescent device with the conventional structure obtained in Comparative Example 1 were placed in the same driving electric field for comparison. Figure 3 The voltage variation curve shown is shown, wherein the abscissa represents the voltage and the ordinate represents the luminous brightness.

[0123] Figure 3 The curves showing the change of the luminance of the device with the alternating voltage under the same driving electric field in Example 1 and Comparative Example 1 are shown. Figure 3 It can be seen that compared with traditional electroluminescent devices, the electroluminescent devices obtained in the embodiments of the present invention have lower lighting voltage and higher luminous intensity, indicating that the electroluminescent devices based on the novel hole generation structure obtained in the embodiments of the present invention have significantly improved luminescent performance compared with traditional electroluminescent devices, and the performance of the electroluminescent devices has been significantly improved.

[0124] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, improvements, etc. made within the spirit and principle of the present invention should be included in the protection scope of the present invention.

[0125] For the method embodiments, for the sake of simplicity, they are all described as a series of action combinations, but those skilled in the art should know that the present invention is not limited by the order of the actions described, because according to the present invention, some steps can be performed in other orders or simultaneously. Secondly, those skilled in the art should also know that the embodiments described in the specification are all preferred embodiments, and the actions and components involved are not necessarily required by the present invention.

[0126] 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.

[0127] It should also be noted that, in this article, the orientation or position relationship indicated by the terms "upper", "lower", "left", "right", "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 invention and simplifying the description, rather than indicating or implying 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 of the present invention. 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 term "include" or any other variant thereof is 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 other elements not explicitly listed, or also includes elements inherent to such process, method, article or terminal device.

[0128] The above is a detailed introduction to an electroluminescent device based on a novel hole generating structure and a preparation method provided by the present application. The principle and implementation method of the present application are described in detail 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 a person skilled 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 protection scope of the present application.

Claims

1. An electroluminescent device based on a novel hole generating structure, characterized in that: The electroluminescent device comprises: a transparent substrate, and the following components which are sequentially located on a surface of one side of the transparent substrate: A first insulating layer, a novel hole generating layer, a hole transporting layer, a light emitting layer, an electron generating layer, a second insulating layer and a metal electrode; The novel hole generating layer comprises nano-particle material and hole generating material, and the doping concentration of the nano-particle material in the hole generating material is 1%-80%.

2. The electroluminescent device based on the novel hole generating structure according to claim 1, characterized in that: The nanoparticle material is MoO3 nanomaterial, MoS2 nanomaterial, NiO x Any of the nanomaterials and WS2.

3. The electroluminescent device based on the novel hole generating structure according to claim 1, characterized in that: The hole transport layer comprises any one of PVK, HAT-CN, TFB and PF8CZ.

4. The electroluminescent device based on the novel hole generating structure according to claim 1, characterized in that: The constituent materials of the light-emitting layer include any one of CdSe / ZnS quantum dots, CdSe / ZnSe quantum dots, InP / ZnS quantum dots and ZnSe / ZnS quantum dots, and any one of organic light-emitting materials and perovskite light-emitting materials.

5. The electroluminescent device based on the novel hole generating structure according to claim 1, characterized in that: The constituent material of the electron generating layer includes any one of ZnMgO, PEDOT:PSS, ZnO, ZnSnO, B4PYMPM, B3PYMPM, BmPYPB, TmPYPB, TPBi and Bphen, and any one of MXENE, PCBM and 3TPYMB.

6. The electroluminescent device based on the novel hole generating structure according to claim 1, characterized in that: The composition material of the insulating layer includes any one of PVDF, P (VDF-TRFE-CFE), LiF, HfO2, PMMA and PVDF-HFP; Wherein, the insulating layer includes the first insulating layer and / or the second insulating layer.

7. The electroluminescent device based on the novel hole generating structure according to claim 1, characterized in that: The transparent substrate is a hard substrate or a flexible substrate; wherein the constituent material of the hard substrate includes any one of glass, silicon dioxide and quartz, and the constituent material of the flexible substrate includes any one of polyethylene terephthalate, polyethylene naphthalate and polyimide.

8. A method for preparing an electroluminescent device based on a novel hole generating structure, characterized in that: The preparation method is applied to prepare the electroluminescent device based on the novel hole generating structure as described in any one of claims 1 to 7, and the method comprises: Step 1, cleaning the transparent substrate, and coating the surface of the cleaned transparent substrate with an insulating material to sequentially form a first insulating layer; Step 2, coating the mixed solution on the transparent substrate obtained in step 1 to form a novel hole generating layer; wherein the mixed solution is obtained by mixing a nanoparticle material and a hole generating material, and the doping concentration of the nanoparticle material in the hole generating material is 1%-80%; Step 3, coating a hole transport material, a luminescent material, an electron generating material and an insulating material on the novel hole generating layer obtained in step 2 in sequence to form a hole transport layer, a luminescent layer, an electron generating layer and a second insulating layer in sequence; Step 4, evaporating a metal electrode on the transparent substrate obtained in step 3 to obtain the electroluminescent device based on the novel hole generating structure.

9. The method for preparing an electroluminescent device based on a novel hole generating structure according to claim 8, characterized in that: In step 2, the steps of preparing the mixed solution include: Step 2-1, dissolving the hole generating material and the nanoparticle material into a solvent respectively to obtain a first solution and a second solution; Step 2-2, doping the second solution into the first solution at a concentration ratio of 1%-80% to obtain the mixed solution.

10. The method for preparing an electroluminescent device based on a novel hole generating structure according to claim 8, characterized in that: In the step 1, the transparent substrate is cleaned, including: Step 1-1, ultrasonically cleaning the transparent substrate using an ultrasonic cleaning apparatus containing a washing solution, deionized water and anhydrous ethanol; Step 1-2, performing nitrogen drying treatment on the transparent substrate after the ultrasonic cleaning to remove organic matter and dust on the transparent substrate.

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