CN113206203B - Electroluminescent device, preparation method thereof and display device - Google Patents
Electroluminescent device, preparation method thereof and display device Download PDFInfo
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- CN113206203B CN113206203B CN202010431035.6A CN202010431035A CN113206203B CN 113206203 B CN113206203 B CN 113206203B CN 202010431035 A CN202010431035 A CN 202010431035A CN 113206203 B CN113206203 B CN 113206203B
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- H—ELECTRICITY
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- H10K—ORGANIC ELECTRIC SOLID-STATE DEVICES
- H10K50/00—Organic light-emitting devices
- H10K50/10—OLEDs or polymer light-emitting diodes [PLED]
- H10K50/14—Carrier transporting layers
- H10K50/15—Hole transporting layers
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- H—ELECTRICITY
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- H10K—ORGANIC ELECTRIC SOLID-STATE DEVICES
- H10K50/00—Organic light-emitting devices
- H10K50/10—OLEDs or polymer light-emitting diodes [PLED]
- H10K50/11—OLEDs or polymer light-emitting diodes [PLED] characterised by the electroluminescent [EL] layers
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- H—ELECTRICITY
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- H10K71/12—Deposition of organic active material using liquid deposition, e.g. spin coating
Abstract
The invention discloses an electroluminescent device which comprises a cathode layer, an electron transport layer, a light emitting layer, a hole transport layer and an anode layer, wherein the cathode layer and the anode layer are arranged oppositely, the light emitting layer is arranged between the cathode layer and the anode layer, the electron transport layer is arranged between the cathode layer and the light emitting layer, the hole transport layer is arranged between the anode layer and the light emitting layer, a quantum dot light emitting material is arranged in the light emitting layer, the contact surface of the electron transport layer and the light emitting layer is a first interface, the contact surface of the hole transport layer and the light emitting layer is a second interface, and the roughness of the second interface is larger than that of the first interface. The invention discloses a preparation method of an electroluminescent device. The invention discloses a display device.
Description
Technical Field
The invention relates to the technical field of light-emitting devices, in particular to an electroluminescent device, a preparation method thereof and a display device.
Background
With the continuous development of Organic Light Emitting Display (OLED) technology, the display market shows a trend toward more and more diversified applications, such as flexible display, transparent display, and the like. Among them, having a wider color gamut is becoming a popular requirement. The quantum dot self-luminescent device (QLED) has the characteristics of narrow half-peak width of a luminescent chromatogram and pure chromaticity. On the premise, if the quantum dot light-emitting device is adopted in the display device to realize the light emission of three primary colors of red, green and blue, the wider color gamut can be realized.
Unlike the mature Organic Light Emitting Device (OLED), the quantum dot light emitting device (QLED) is limited by its unique characteristics of electrical balance and energy level so far, and the efficiency and lifetime are often not comparable to the OLED device. This is mainly because the hole level HOMO of a quantum dot light emitting layer (QD) is deep and tends to be difficult to match with the shallow HOMO level of a conventional hole transport material (HTL). In addition, QLEDs tend to employ oxides such as zinc oxide ZnO for their electron injection and transport layers (ETL), while the hole transport capabilities tend to be low compared to conventional HTLs. For these reasons, in the QD exciton recombination region, it is often difficult to match the injection of holes with the injection of electrons, thereby making it difficult to achieve electrical balance, and thus reducing the luminous efficiency, or the current imbalance between holes and electrons due to a slight change in the device after a certain operation time, thereby resulting in a short operation life.
To address this problem, conventional solutions often attempt to optimize electrical balance by transforming HTL or ETL materials, among other means. But this is heavily dependent on the development of new materials and is difficult.
Disclosure of Invention
In view of the above, it is necessary to provide an electroluminescent device capable of achieving current imbalance between holes and electrons without relying on material conversion, a method for manufacturing the same, and a display device, in order to solve the problem that holes and electrons are difficult to match in a QLED.
An electroluminescent device comprises a cathode layer, an electron transport layer, a light emitting layer, a hole transport layer and an anode layer, wherein the cathode layer and the anode layer are arranged oppositely, the light emitting layer is arranged between the cathode layer and the anode layer, the electron transport layer is arranged between the cathode layer and the light emitting layer, the hole transport layer is arranged between the anode layer and the light emitting layer, a quantum dot light emitting material is arranged in the light emitting layer, the electron transport layer and the contact surface of the light emitting layer are first interfaces, the hole transport layer and the contact surface of the light emitting layer are second interfaces, and the roughness of the second interfaces is larger than the first interfaces.
In one embodiment, the ratio of the roughness of the second interface to the roughness of the first interface is (1.5-20): (0.1-1).
In one embodiment, the root-mean-square roughness of the second interface is 1.5nm to 20 nm; and/or the root mean square roughness of the first interface is 0.1 nm-1 nm.
In one embodiment, the hole transport layer comprises first hole transport material particles and second hole transport material particles, the particle diameter ratio of the first hole transport material particles to the second hole transport material particles is 1: 5-1: 10, and the mass ratio of the first hole transport material particles to the second hole transport material particles is 1: 1-1: 10.
In one embodiment, the light-emitting layer comprises first light-emitting material particles and second light-emitting material particles, the particle diameter ratio of the first light-emitting material particles to the second light-emitting material particles is 1:5 to 1:10, and the mass ratio of the first light-emitting material particles to the second light-emitting material particles is 1:1 to 1: 10.
In one embodiment, the particle uniformity of the luminescent material of the luminescent layer near the first interface is higher than the particle uniformity of the luminescent material of the luminescent layer near the second interface.
In one embodiment, the light-emitting layer is a continuous phase with a void ratio of 0-5%.
In one embodiment, the hole transport layer is a continuous phase with a void ratio of 0-5%.
In one embodiment, the electron transport layer is a continuous phase with a void ratio of 0-5%.
In one embodiment, the first interface is a planar surface and the second interface is an etched patterned surface.
A method for preparing an electroluminescent device comprises the following steps:
forming a cathode layer on a substrate;
forming an electron transport layer on the cathode layer;
forming a luminescent layer on the electron transport layer, wherein the contact surface of the electron transport layer and the luminescent layer is a first interface;
forming a hole transport layer on the light-emitting layer, wherein the contact surface of the hole transport layer and the light-emitting layer is a second interface, so that the roughness of the second interface is greater than that of the first interface; and
an anode layer is formed on the hole transport layer.
A preparation method of an electroluminescent device comprises the following steps: forming an anode layer on a substrate;
forming a hole transport layer on the anode layer;
forming a luminescent layer on the hole transport layer, wherein the contact surface of the hole transport layer and the luminescent layer is a second interface;
forming an electron transport layer on the light-emitting layer, wherein the contact surface of the electron transport layer and the light-emitting layer is a first interface, so that the roughness of the second interface is greater than that of the first interface; and
and forming a cathode layer on the electron transport layer.
In one embodiment, in the step of forming the light-emitting layer on the electron transport layer, the step of forming the light-emitting layer by a solution drying film-forming method includes loading a light-emitting material dispersion on the electron transport layer and drying, wherein the temperature of the substrate is 30 ℃ to 180 ℃ and the vacuum pressure of the environment is 10 DEG C -6 Pa to 1 standard atmosphere, and the viscosity of the luminescent material dispersion liquid is 1 cp-15 cp.
In one embodiment, the step of forming the hole transport layer on the anode layer, in which the hole transport layer is formed by a solution drying film-forming method, includes loading a hole transport material dispersion liquid on the anode layer and drying, where the temperature of the substrate is 30 to 250 ℃ and the vacuum pressure of the environment is 10 ℃ when drying -6 Pa to 1 standard atmospheric pressure, and the viscosity of the hole transport material dispersion liquid is 1cp to 15 cp.
In one embodiment, in the step of forming the light-emitting layer on the hole transport layer, the step of forming the light-emitting layer by a solution drying film-forming method includes loading a light-emitting material dispersion on the hole transport layer and drying, wherein the temperature of the substrate is 20 ℃ to 270 ℃ and the vacuum pressure of the environment is 10 DEG C -6 Pa to 1 standard atmosphere, and the viscosity of the luminescent material dispersion liquid is 1 cp-15 cp.
A display device comprises the electroluminescent device.
The inventor finds that under the condition of the same injection energy level, the injection surface is rougher, and the injected current is larger, and can effectively regulate and control the electrical balance of electron and hole currents on the premise of not changing materials by changing the roughness of a Hole Transport Layer (HTL)/luminescent layer (QD) interface and a QD/Electron Transport Layer (ETL) interface. Unlike the structure design of the traditional planar laminated device, the electroluminescent device structure of the invention introduces a non-planar structure. By controlling the roughness of the HTL/QD interface to be larger than that of the QD/ETL interface, hole injection can be relatively increased, so that the electric balance of hole and electron current in the electroluminescent device is improved, and the efficiency and the service life of the electroluminescent device, particularly a quantum dot light-emitting device, are effectively improved.
Drawings
FIG. 1 is a schematic structural diagram of an electroluminescent device according to an embodiment of the present invention;
fig. 2 is a schematic structural view of a conventional electroluminescent device.
Detailed Description
To facilitate an understanding of the invention, the invention will now be described more fully with reference to the accompanying drawings. Preferred embodiments of the present invention are shown in the drawings. This invention 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 invention belongs. The terminology used in the description of the invention herein is for the purpose of describing particular embodiments only and is not intended to be limiting of the invention. As used herein, the term "and/or" includes any and all combinations of one or more of the associated listed items.
Referring to fig. 1, an electroluminescent device according to an embodiment of the present invention includes a cathode layer 10, an electron transport layer 20, a light emitting layer 30, a hole transport layer 40, and an anode layer 50, where the cathode layer 10 is disposed opposite to the anode layer 50, the light emitting layer 30 is disposed between the cathode layer 10 and the anode layer 50, the electron transport layer 20 is disposed between the cathode layer 10 and the light emitting layer 30, the hole transport layer 40 is disposed between the anode layer 50 and the light emitting layer 30, the light emitting layer 30 has a quantum dot light emitting material therein, a contact surface between the electron transport layer 20 and the light emitting layer 30 is a first interface, a contact surface between the hole transport layer 40 and the light emitting layer 30 is a second interface, and a roughness of the second interface is greater than that of the first interface.
The electroluminescent device of the embodiment of the invention is mainly used for solving the problem of unbalanced injection of electrons and holes, and the inventor finds that under the condition of the same injection energy level, the rougher the injection surface is, and the larger the injected current is, and can effectively regulate and control the electrical balance of the current of the electrons and the holes by changing the roughness of the interface of the hole transport layer 40 (HTL)/the luminescent layer 30(QD) and the interface of the QD/electron transport layer 20(ETL) on the premise of not changing materials. Unlike the conventional planar stacked device structure design (see fig. 2), the electroluminescent device structure according to the embodiment of the present invention has a non-planar structure. By controlling the roughness of the HTL/QD interface to be larger than that of the QD/ETL interface, hole injection can be relatively increased, so that the electric balance of hole and electron current in the electroluminescent device is improved, and the efficiency and the service life of the electroluminescent device, particularly a quantum dot light-emitting device, are effectively improved.
The electroluminescent device of the embodiment of the invention can be of a positive structure or an inverted structure. In an electroluminescent device having a front-mounted structure, an anode layer 50 is provided on a substrate, and a hole transport layer 40, a light-emitting layer 30, an electron transport layer 20, and a cathode layer 10 are stacked on the anode layer 50. In an inverted electroluminescent device, a cathode layer 10 is provided on a substrate, and an electron transport layer 20, a light-emitting layer 30, a hole transport layer 40, and an anode layer 50 are stacked on the cathode layer 10.
In one embodiment, the electroluminescent device may be a light emitting layer 30 formed of a quantum dot light emitting material, forming a quantum dot autonomous light emitting device (QLED); or a material in which an organic light-emitting material and a quantum dot light-emitting material are mixed, to form a light-emitting layer 30, and to form a device in which an organic light-emitting device (OLED) and a QLED are mixed.
In one embodiment, the ETL/QD interface (first interface) may be planar and the QD/HTL interface (second interface) may be roughened. In another embodiment, the ETL/QD interface and the QD/HTL interface are both rough surfaces, and the QD/HTL interface is more rough than the ETL/QD interface. In one embodiment, the first interface is a planar surface and the second interface is an etched patterned surface. In one embodiment, the surface of the light-emitting layer 30 in contact with the electron transport layer 20 is a flat surface, and the surface of the light-emitting layer 30 in contact with the hole transport layer 40 is an etched patterned surface. By "planar" is meant a relatively smooth surface, e.g., a surface having a root mean square roughness (Rq) of less than 0.3 nm.
In one embodiment, the roughness of the second interface is more than 1.5 times the roughness of the first interface. That is, Rq (QD/HTL) ≧ 1.5Rq (ETL/QD). Preferably, the ratio of the roughness of the second interface to the roughness of the first interface can be (1.5-20): (0.1-1). In one embodiment, the root mean square roughness of the first interface is 0.1nm to 1 nm. Specifically, the root-mean-square roughness of the first interface is 0.1nm to 0.2nm, 0.2nm to 0.3nm, 0.3nm to 0.4nm, 0.4nm to 0.5nm, 0.5nm to 0.6nm, 0.6nm to 0.7nm, 0.7nm to 0.8nm, 0.8nm to 0.9nm, or 0.9nm to 1 nm. In one embodiment, the root mean square roughness of the second interface is 1.5nm to 20 nm. Specifically, the root-mean-square roughness of the second interface is 1.5nm to 2nm, 2nm to 4nm, 4nm to 6nm, 6nm to 8nm, 8nm to 0.6nm, 0.6nm to 10nm, 10nm to 12nm, 12nm to 14nm, 14nm to 16nm, 16nm to 18nm or 18nm to 20 nm.
The present invention can control the roughness difference of the QD/HTL interface and the ETL/QD interface by controlling the particle type of the functional material of the hole transport layer 40, the light emitting layer 30, or the electron transport layer 20 or the film forming process.
In one embodiment, the particle size ratio of the electron transport material particles in the electron transport layer 20 is 1 (0.8-1.2). That is, the electron transport material has a relatively uniform particle size, which enables a relatively flat surface to be formed, resulting in a low roughness of the ETL/QD interface.
In one embodiment, the electroluminescent device is a positive structure, the hole transport layer 40 is formed first, and then the light-emitting layer 30 is formed. The hole transport layer 40 includes at least two kinds of hole transport material particles having different particle diameters, including first hole transport material particles and second hole transport material particles. In one embodiment, the ratio of the particle diameters of the first hole transport material particles to the second hole transport material particles is 1:5 to 1: 10. In one embodiment, the mass ratio of the first hole transport material particles to the second hole transport material particles is 1:1 to 1: 10. In one embodiment, the first hole transport material particles are planar material particles, such as regular hexagonal particles; the second hole transport material particles are spherical or spheroidal particles. The surface of the hole transport layer 40 connected to the light emitting layer 30 is made rough by controlling the unevenness of the particle diameter of the hole transport material particles or the shape difference of the particles, thereby improving the roughness of the QD/HTL interface. In one embodiment, the particle size of the hole transport material particles is 5nm to 50 nm. Specifically, the particle size may be 5nm to 15nm, 15nm to 20nm, 20nm to 25nm, 25nm to 30nm, 30nm to 35nm, 35nm to 40nm, 40nm to 45nm, or 45nm to 50 nm.
In one embodiment, the electroluminescent device is an inverted structure, wherein the electron transport layer 20 is formed first, and then the light-emitting layer 30 and the hole transport layer 40 are formed. The light-emitting layer 30 includes at least two different particle sizes of light-emitting material particles, and the at least two different particle sizes of light-emitting material particles include a first light-emitting material particle and a second light-emitting material particle. In an embodiment, a ratio of the first luminescent material particles to the second luminescent material particles is 1:5 to 1: 10. In an embodiment, a mass ratio of the first luminescent material particles to the second luminescent material particles is 1:1 to 1: 10. In an embodiment, the first luminescent material particles are planar material particles, for example regular hexagonal particles; the second luminescent material particles are spherical or spheroidal particles. The roughness of the QD/HTL interface is improved by controlling the unevenness of the particle diameter of the light emitting material particles or the shape difference of the particles so that the surface of the light emitting layer 30 connected to the hole transport layer 40 is a rough surface. In one embodiment, the particle size of the luminescent material particles is 5nm to 50 nm. Specifically, the particle size may be 5nm to 15nm, 15nm to 20nm, 20nm to 25nm, 25nm to 30nm, 30nm to 35nm, 35nm to 40nm, 40nm to 45nm, or 45nm to 50 nm.
In one embodiment, the particle uniformity of the luminescent material of the luminescent layer 30 near the first interface is higher than the particle uniformity of the luminescent material of the luminescent layer 30 near the second interface. The roughness of both surfaces of the light emitting layer 30 is made different by the difference in particle diameter gradient, and the roughness of the surface connected with the electron transport layer 20 is smaller than that of the surface connected with the hole transport layer 40.
In one embodiment, the light-emitting layer 30 is a continuous phase with a void ratio of 0-5%. That is, the inside of the light emitting layer 30 is continuously filled and dense, and has no void or a void ratio of 5% or less. In one embodiment, the hole transport layer 40 is a continuous phase with a porosity of 0-5%. That is, the inside of the hole transport layer 40 is continuously filled and dense, and has no void or a void ratio of 5% or less. In one embodiment, the electron transport layer 20 is a continuous phase with a porosity of 0-5%. That is, the inside of the electron transport layer 20 is continuously filled and dense, and has no void or a void ratio of 5% or less. By forming the continuous phase, the defects of the thin film such as holes can be reduced, thereby being beneficial to reducing the interface recombination, reducing the phenomena of leakage current and the like of the device.
In one embodiment, the electron transport material may be an n-type semiconductor metal oxide. The n-type semiconductor metal oxide has good water and oxygen resistance, excellent conductivity and better light transmission. In one embodiment, the n-type semiconducting metal oxide may be selected from ZnO, MoO, TiO 2 、SnO 2 And In 2 O 3 One or more of (a).
The light emitting material in the light emitting layer 30 may be selected from a quantum dot light emitting material or a mixture of a quantum dot light emitting material and an organic light emitting material. In an embodiment, the quantum dot luminescent material may be selected from one or more of a group II-VI compound semiconductor, a group III-V compound semiconductor, a group I-III-VI compound semiconductor, and a perovskite quantum dot. Wherein the II-VI compound semiconductor may include one or more of ZnCdSeS, CdSe/CdS, CdSeS/CdS, CdSe/CdS/ZnS, ZnCdSeS/ZnS, and ZnCdS/ZnS. The III-V compound semiconductor may include one or both of InP and InP/ZnS. The group I-III-VI compound semiconductor may include one or more of CuInS, AgInS, CuInS/ZnS, and AnInS/ZnS. Calcium carbonateThe titanium ore quantum dots can be CsPbM 3 (M ═ Cl, Br, I). Of course, the quantum dot light emitting material is not limited to the above materials. In an embodiment, the organic light emitting material may be selected from one or more of a fluorescent material, a phosphorescent material, and a Thermally Activated Delayed Fluorescence (TADF) material. The fluorescent material may include one or more of TPBe, TTPA, TBRb, and DBP, among others. The phosphorescent material may comprise one or more of Firpic, Ir (ppy)3, Ir (ppy)2acac, and Ir (piq) 3. The TADF material may include one or more of ACRSA, DIC-TRZ, 2CzPN, PXZ-TRZ, pcnbczo cf 3. Of course, the organic light emitting material is not limited to the above materials.
In one embodiment, hole transport layer 40 has a hole transport material therein having a triplet energy sufficiently large to improve the electrical balance of holes and electrons, greater than the energy of the luminescent QD excitons. In one embodiment, the hole transport material has high hole transport capability and hole mobility greater than 10 -3 cm 2 Vs. In one embodiment, the hole transport layer 40 has a composite structure of a high triplet material and a high mobility material. In one embodiment, the hole transport material may be selected from one or both of organic and inorganic substances. The organic matter may include one or more of Poly-TPD, TFB, PVK, TCTA, CBP, NPB, and NPD. The inorganic substance may include NiO and Cu 2 One or more of O and CuSCN. Preferably, the hole transport material is an organic material. In an embodiment, the electroluminescent device comprises a hole injection layer, which is provided between the anode layer 50 and the hole transport layer 40. In the hole injection layer and the hole transport layer 40, the kinds of hole functional materials may be the same or different. In one embodiment, the hole injection layer has a hole injection material therein, and the hole injection material may be selected from one or both of a conductive polymer and an n-type semiconductor. The conductive polymer may be PEDOT PSS. The n-type semiconductor may comprise HAT-CN, MoO 3 、WO 3 、V 2 O 5 And Rb 2 One or more of O.
The cathode layer 10 may be a conventional cathode material such as ITO glass. The anode layer 50 can be a conventional anode material such as aluminum. The electroluminescent device may further include a substrate provided under the cathode layer 10 or the anode layer 50, and the substrate may be a flexible substrate such as polyimide or a rigid substrate such as glass, which is not particularly limited.
In one embodiment, the thickness of the cathode layer 10 may be 40nm to 60 nm. In one embodiment, the thickness of the electron transport layer 20 may be 30nm to 60 nm. In one embodiment, the thickness of the light emitting layer 30 may be 20nm to 40 nm. In one embodiment, the thickness of the hole transport layer 40 may be 30nm to 40 nm. In one embodiment, the thickness of the hole injection layer may be 10nm to 20 nm. In one embodiment, the anode layer 50 may have a thickness of 80nm to 120 nm. May not be limited to the above layer thicknesses. Since the present application relates to the problem of roughness of the functional layer, there may be cases where the thicknesses at the respective locations are different, where the thickness refers to the maximum thickness at both ends of the functional layer.
The implementation of the invention also provides a preparation method of the electroluminescent device, wherein the electroluminescent device is of an inverted structure, and the preparation method comprises the following steps:
forming a cathode layer 10 on the substrate;
forming an electron transport layer 20 on the cathode layer 10;
forming a light-emitting layer 30 on the electron transport layer 20, wherein the contact surface of the electron transport layer 20 and the light-emitting layer 30 is a first interface;
forming a hole transport layer 40 on the light-emitting layer 30, wherein the contact surface of the hole transport layer 40 and the light-emitting layer 30 is a second interface, so that the roughness of the second interface is greater than that of the first interface; and
an anode layer 50 is formed on the hole transport layer 40.
In one embodiment, the electron transport layer 20 may be formed by a solution dry film forming method or an evaporation method.
In an embodiment, the method for making the roughness of the second interface larger than the roughness of the first interface may be: the roughness of the surface of the light-emitting layer 30 remote from the electron transport layer 20 is made larger than the roughness of the surface of the light-emitting layer 30 connected to the electron transport layer 20.
In one embodiment, in the step of forming the light emitting layer 30 on the electron transport layer 20, the light emitting layer 30 may be formed by a solution drying film forming method including loading a light emitting material dispersion on the electron transport layer 20 and drying. When drying, the temperature of the substrate is controlled to be 30-180 ℃, and the vacuum pressure of the environment is 10 DEG -6 Pa to 1 standard atmosphere, the surface of the light-emitting layer 30 connected with the hole transport layer 40 can form a rough surface, and the relative injection of holes is improved, but other performances of the electro-optical device are not affected basically.
In one embodiment, in the step of forming the light emitting layer 30 on the electron transport layer 20, the step of forming the light emitting layer 30 by a solution drying film forming method includes loading a light emitting material dispersion liquid on the electron transport layer 20 and drying, wherein the viscosity of the light emitting material dispersion liquid is 1cp to 15 cp. Preferably 3cp to 10 cp. By controlling the viscosity of the luminescent material dispersion, a relatively rough surface is formed in a film manner. In one embodiment, the solvent in the phosphor dispersion may be selected from one or more of isobutanol, octylbenzene, n-octane, and methyl benzoate.
The embodiment of the invention also provides a preparation method of the electroluminescent device, the electroluminescent device is of a positive structure, and the preparation method comprises the following steps:
forming an anode layer 50 on the substrate;
forming a hole transport layer 40 on the anode layer 50;
forming a light-emitting layer 30 on the hole transport layer 40, wherein the contact surface of the hole transport layer 40 and the light-emitting layer 30 is a second interface;
forming an electron transport layer 20 on the light emitting layer 30, wherein the contact surface of the electron transport layer 20 and the light emitting layer 30 is a first interface, so that the roughness of the second interface is greater than that of the first interface; and
a cathode layer 10 is formed on the electron transport layer 20.
In an embodiment, the roughness of the second interface is greater than the roughness of the first interface, such that the roughness of the surface of the hole transport layer 40 connected to the light emitting layer 30 is greater than the roughness of the surface of the light emitting layer 30 away from the hole transport layer 40.
In the step of forming the hole transport layer 40 on the anode layer 50, the hole transport layer 40 may be formed by a solution drying film-forming method including supporting a dispersion of a hole transport material on the anode layer 50 and drying. When drying, the temperature of the substrate is controlled to be 30-250 ℃, and the vacuum pressure of the environment is 10 DEG -6 Pa to 1 atm, so that the surface of the hole transport layer 40 connected to the light emitting layer 30 forms a relatively rough surface. The viscosity of the hole transport material dispersion in one embodiment may be 1cp to 15 cp. Preferably 5cp to 9 cp. In one embodiment, the solvent in the hole transport material dispersion may be selected from one or more of xylene, methyl benzoate, n-hexane, and polyvinylpyrrolidone.
In the step of forming the light-emitting layer 30 on the hole transport layer 40, the light-emitting layer 30 may be formed by a solution drying film-forming method including supporting a light-emitting material dispersion on the hole transport layer 40 and drying. During drying, the temperature of the substrate is controlled to be 20-270 ℃, and the vacuum pressure of the environment is 10 DEG -6 Pa to 1 atm so that the surface of the light emitting layer 30 connected to the electron transport layer 20 forms a relatively smooth plane. In one embodiment, the viscosity of the light emitting material dispersion may be 1cp to 15 cp. Preferably 3cp to 13 cp.
Of course, the above film forming process is preferably coordinated with the particle type to improve the roughness difference of the QD/HTL interface and the ETL/QD interface.
The embodiment of the invention also provides a display device which comprises the electroluminescent device of any one of the embodiments or the electroluminescent device prepared by any one of the preparation methods.
The following are specific examples.
Example 1
(1) The transparent conductive film ITO is used as the cathode layer 10, and the thickness is 50 nm.
(2) An electron transport material ZnO was deposited on the cathode layer 10 using a solution method to obtain an electron transport layer 20 having a thickness of 20 nm. The ZnO solution is a nanoparticle dispersion with a viscosity of 10 cps. The substrate temperature was 180 ℃ during drying. The vacuum pressure of the environment is 2 x 10 -5 Pa. The particle size of the ZnO nano-particles is 2 nm-50 nm, wherein the number of the particles with the particle size of 2 nm-10 nm accounts for 60%, and the number of the particles with the particle size of 40 nm-50 nm accounts for 30%. After drying to form a film, the surface roughness of the electron transport layer 20 was about Rq 2.3 nm.
(3) ZnCdS/ZnS quantum dot material is deposited on the electron transport layer 20 by a solution drying film forming method to be used as a quantum dot light emitting layer 30, and the thickness is 20 nm. The viscosity of the quantum dot material dispersion liquid in the solution drying film-forming method is 7cp, the temperature of the substrate is 80 ℃ during drying, and the vacuum pressure of the environment is 2 x 10 -5 Pa. The particle size of the quantum dot material is 5 nm-50 nm, wherein the number of particles with the particle size of 5 nm-10 nm accounts for 30%, and the number of particles with the particle size of 40 nm-50 nm accounts for 30%. The surface roughness of the light-emitting layer 30 away from the electron transport layer 20 is about Rq-8 nm.
(4) CPB was deposited as the hole transport layer 40 on the light emitting layer 30 by an evaporation method to a thickness of 30 nm.
(5) HAT-CN was deposited as a hole injection layer on the hole transport layer 40 by evaporation to a thickness of 15 nm.
(6) Al was deposited as an anode layer 50 on the hole injection layer by evaporation to a thickness of 100 nm.
Example 2
(1) Al was used as the anode layer 50, and the thickness was 90 nm.
(2) HAT-CN was deposited as a hole injection layer on the anode layer 50 using a solution method to a thickness of 15 nm.
(3) A CPB hole transport material was deposited as the hole transport layer 40 on the hole injection layer by a solution drying film formation method with a thickness of 30 nm. The viscosity of the hole transport material dispersion in the solution drying film formation method was 7cp, and the substrate temperature was 150 ℃ and the ambient vacuum pressure was 10 ℃ at the time of drying -3 Pa, during drying, the hole transport layer forms a relief surface under the action of heat. The surface roughness of the hole transport material layer was about Rq ═ 15 nm.
(4)And depositing a ZnCdS/ZnS quantum dot material on the hole transport layer 40 by an evaporation deposition solution drying film forming method to form the quantum dot light emitting layer 30 with the thickness of 20 nm. The viscosity of the quantum dot material dispersion in the solution drying film-forming method was 6cp, and the temperature of the substrate was 90 ℃ and the vacuum pressure of the atmosphere was 10 ℃ during drying -5 Pa. The particle size of the quantum dot material is 5 nm-10 nm. The surface roughness of the light-emitting layer 30 away from the hole transport layer 40 is about Rq ═ 8 nm.
(5) The electron transport layer 20 having a thickness of 20nm was obtained by depositing ZnO, which is an electron transport material, on the light-emitting layer 30 by an evaporation method.
(6) A transparent conductive thin film ITO as a cathode layer 10 was disposed on the electron transport layer 20 to a thickness of 50 nm.
Comparative example 1
Comparative example 1 is substantially the same as example 1 except that in step (2), the average size of nanoparticles is larger: the particle size of the ZnO nano-particles is 10 nm-50 nm, wherein the number of the particles with the particle size of 10 nm-20 nm accounts for 30%, and the number of the particles with the particle size of 40 nm-50 nm accounts for 30%. After drying to form a film, the surface roughness of the electron transport layer 20 was about Rq 15 nm.
The efficiency and lifetime of the electroluminescent devices of examples 1-2 and comparative example 1 were determined under the same experimental conditions, and the results are shown in table 1.
TABLE 1 Properties of the different electroluminescent devices
As can be seen from table 1 above, the efficiency and lifetime of the electroluminescent device of the embodiment of the present invention are significantly higher than those of the electroluminescent device of the comparative example, which shows that the embodiment of the present invention effectively improves the performance of the electroluminescent device.
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 invention, 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 inventive concept, which falls within the scope of the present invention. Therefore, the protection scope of the present patent shall be subject to the appended claims.
Claims (11)
1. An electroluminescent device is characterized by comprising a cathode layer, an electron transport layer, a light emitting layer, a hole transport layer and an anode layer, wherein the cathode layer and the anode layer are arranged oppositely, the light emitting layer is arranged between the cathode layer and the anode layer, the electron transport layer is arranged between the cathode layer and the light emitting layer, the hole transport layer is arranged between the anode layer and the light emitting layer, a quantum dot light emitting material is arranged in the light emitting layer, the contact surface of the electron transport layer and the light emitting layer is a first interface, the contact surface of the hole transport layer and the light emitting layer is a second interface, and the roughness of the second interface is larger than that of the first interface; the light-emitting layer comprises first light-emitting material particles and second light-emitting material particles, the particle diameters of the first light-emitting material particles and the second light-emitting material particles are different, and the particle uniformity of the light-emitting material, close to the first interface, of the light-emitting layer is higher than the particle uniformity of the light-emitting material, close to the second interface, of the light-emitting layer through the particle diameter gradient difference.
2. The electroluminescent device of claim 1, wherein the ratio of the roughness of the second interface to the roughness of the first interface is (1.5-20) to (0.1-1).
3. The electroluminescent device of claim 1, wherein the second interface has a root mean square roughness of 1.5nm to 20 nm.
4. The electroluminescent device of claim 1, wherein the first interface has a root mean square roughness of 0.1nm to 1 nm.
5. The electroluminescent device according to claim 1, wherein the hole transport layer comprises first hole transport material particles and second hole transport material particles, the particle diameter ratio of the first hole transport material particles to the second hole transport material particles is 1:5 to 1:10, and the mass ratio of the first hole transport material particles to the second hole transport material particles is 1:1 to 1: 10.
6. The electroluminescent device according to claim 1, wherein the ratio of the first luminescent material particles to the second luminescent material particles is 1:5 to 1:10, and the mass ratio of the first luminescent material particles to the second luminescent material particles is 1:1 to 1: 10.
7. The electroluminescent device according to claim 1, wherein the light-emitting layer is a continuous phase having a void ratio of 0 to 5%; and/or the hole transport layer is a continuous phase with a void ratio of 0-5%; and/or the electron transport layer is a continuous phase with a void ratio of 0-5%.
8. The device of claim 1, wherein the first interface is planar and the second interface is an etched patterned surface.
9. A method for preparing an electroluminescent device comprises the following steps:
forming a cathode layer on a substrate;
forming an electron transport layer on the cathode layer;
forming a luminescent layer on the electron transport layer, wherein the contact surface of the electron transport layer and the luminescent layer is a first interface, the luminescent layer comprises first luminescent material particles and second luminescent material particles, and the particle diameters of the first luminescent material particles and the second luminescent material particles are different;
forming a hole transport layer on the light-emitting layer, wherein the contact surface of the hole transport layer and the light-emitting layer is a second interface, so that the roughness of the second interface is greater than that of the first interface, and the particle uniformity of the light-emitting material of the light-emitting layer close to the first interface is higher than that of the light-emitting material of the light-emitting layer close to the second interface through the particle size gradient difference in the light-emitting layer; and
forming an anode layer on the hole transport layer;
alternatively, the first and second liquid crystal display panels may be,
forming an anode layer on a substrate;
forming a hole transport layer on the anode layer;
forming a light-emitting layer on the hole transport layer, wherein the contact surface of the hole transport layer and the light-emitting layer is a second interface, the light-emitting layer comprises first light-emitting material particles and second light-emitting material particles, and the particle diameters of the first light-emitting material particles and the second light-emitting material particles are different;
forming an electron transport layer on the light emitting layer, wherein a contact surface of the electron transport layer and the light emitting layer is a first interface, so that the roughness of the second interface is larger than that of the first interface, and the particle uniformity of the light emitting material of the light emitting layer close to the first interface is higher than that of the light emitting material of the light emitting layer close to the second interface through the particle size gradient difference in the light emitting layer; and
and forming a cathode layer on the electron transport layer.
10. The method of claim 9, wherein the step of forming the light-emitting layer on the electron transport layer comprises forming the light-emitting layer by a solution drying film-forming method, wherein the step of forming the light-emitting layer on the electron transport layer comprises drying the electron transport layer while supporting the light-emitting material dispersion on the substrate at a temperature of 30 ℃ to 180 ℃ under a vacuum atmosphere of 10 ° f -6 Pa to 1 standard atmosphere, and the luminescent material dispersion liquidThe viscosity of (a) is 1 cp-15 cp;
and/or in the step of forming the hole transport layer on the anode layer, forming the hole transport layer by adopting a solution drying film-forming method, wherein the step of forming the hole transport layer comprises the step of loading a hole transport material dispersion liquid on the anode layer and drying, and when drying, the temperature of the substrate is 30-250 ℃, and the vacuum pressure of the environment is 10 DEG C -6 Pa to 1 standard atmospheric pressure, and the viscosity of the hole transport material dispersion liquid is 1 cp-15 cp;
and/or the presence of a gas in the atmosphere,
in the step of forming the light-emitting layer on the hole transport layer, the light-emitting layer is formed by adopting a solution drying film-forming method, which comprises the steps of loading a light-emitting material dispersion liquid on the hole transport layer and drying, wherein the temperature of the substrate is 20-270 ℃, and the vacuum air pressure of the environment is 10 DEG C -6 Pa to 1 standard atmospheric pressure, and the viscosity of the luminescent material dispersion liquid is 1 cp-15 cp.
11. A display device comprising an electroluminescent device according to any one of claims 1 to 8 or an electroluminescent device produced by a method for producing an electroluminescent device according to any one of claims 9 to 10.
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Citations (6)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JP2002313567A (en) * | 2001-04-18 | 2002-10-25 | Sony Corp | Organic electroluminescence element and its manufacturing method |
| CN105870346A (en) * | 2016-04-15 | 2016-08-17 | 深圳市华星光电技术有限公司 | Manufacturing method of LED display screen and LED display screen |
| CN106410056A (en) * | 2016-11-07 | 2017-02-15 | Tcl集团股份有限公司 | Quantum dot light-emitting diode device and preparation method thereof |
| CN109326729A (en) * | 2017-08-01 | 2019-02-12 | Tcl集团股份有限公司 | A kind of QLED device and preparation method thereof |
| CN110649166A (en) * | 2018-06-26 | 2020-01-03 | Tcl集团股份有限公司 | Quantum dot light-emitting diode and preparation method thereof |
| CN110970534A (en) * | 2018-09-29 | 2020-04-07 | Tcl集团股份有限公司 | Nickel oxide film, preparation method thereof and quantum dot light-emitting diode |
Family Cites Families (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN108376745B (en) * | 2018-03-01 | 2020-08-18 | 京东方科技集团股份有限公司 | Quantum dot light-emitting diode, preparation method thereof and display panel |
-
2020
- 2020-05-20 CN CN202010431035.6A patent/CN113206203B/en active Active
Patent Citations (6)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JP2002313567A (en) * | 2001-04-18 | 2002-10-25 | Sony Corp | Organic electroluminescence element and its manufacturing method |
| CN105870346A (en) * | 2016-04-15 | 2016-08-17 | 深圳市华星光电技术有限公司 | Manufacturing method of LED display screen and LED display screen |
| CN106410056A (en) * | 2016-11-07 | 2017-02-15 | Tcl集团股份有限公司 | Quantum dot light-emitting diode device and preparation method thereof |
| CN109326729A (en) * | 2017-08-01 | 2019-02-12 | Tcl集团股份有限公司 | A kind of QLED device and preparation method thereof |
| CN110649166A (en) * | 2018-06-26 | 2020-01-03 | Tcl集团股份有限公司 | Quantum dot light-emitting diode and preparation method thereof |
| CN110970534A (en) * | 2018-09-29 | 2020-04-07 | Tcl集团股份有限公司 | Nickel oxide film, preparation method thereof and quantum dot light-emitting diode |
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