WO2020134205A1

WO2020134205A1 - Manufacturing method for quantum dot light emitting diode, and quantum dot ink

Info

Publication number: WO2020134205A1
Application number: PCT/CN2019/106140
Authority: WO
Inventors: 张节; 向超宇
Original assignee: Tcl科技集团股份有限公司
Priority date: 2018-12-29
Filing date: 2019-09-17
Publication date: 2020-07-02
Also published as: CN111384268B; CN111384268A

Abstract

Disclosed is a manufacturing method for a quantum dot light emitting diode. The method comprises: providing a quantum dot ink, wherein the quantum dot ink comprises a solvent system and quantum dots dispersed in the solvent system, and the solvent system comprises a nonpolar solvent and a dopant compound; and providing a cathode substrate or an anode substrate, depositing the quantum dot ink on the cathode substrate or the anode substrate and then performing light irradiation treatment, and annealing to obtain a quantum dot light emitting layer, wherein the dopant compound can be photo-dissociated into an ionic compound subsequent to the light irradiation treatment.

Description

Preparation method of quantum dot light-emitting diode and quantum dot ink

This application requires the priority of the Chinese patent application filed at the China Patent Office on December 29, 2018, with the application number 201811639169.6 and the application name "Preparation Method of Quantum Dot Light-Emitting Diode and Quantum Dot Ink". The reference is incorporated in this application.

Technical field

The present application relates to the field of display technology, in particular to a method for preparing quantum dot light-emitting diodes, and quantum dot ink.

Background technique

Quantum dots (quantum dots), also known as semiconductor nanocrystals, whose three-dimensional dimensions are in the nanometer range (1-100nm), is a kind of nanoparticle theory between bulk materials and molecules. Quantum dots have excellent optical properties such as high quantum yield, large molar extinction coefficient, good light stability, narrow half-peak width, wide excitation spectrum and controllable emission spectrum, and are very suitable for use as light-emitting materials for light-emitting devices. In recent years, due to its advantages of high light color purity, adjustable light emission color, and long service life, quantum dot fluorescent materials have been widely optimistic for the field of flat panel display, and have become a promising next-generation display and solid-state lighting source. Quantum dot light emitting diode (Quantum Dot Light Emitting Diodes QLED) is a light-emitting device based on quantum dot material as a luminescent material. Due to its advantages of adjustable wavelength, narrow emission spectrum, high stability, high electroluminescence quantum yield, etc. A strong competitor of a generation of display technology.

However, the current preparation method of quantum dot light-emitting diode, quantum dot ink, still needs to be improved.

Application content

The inventor found that in the process of preparing the QLED device by the solution method, due to the material difference between the functional layers, inevitably there will be certain compatibility problems between adjacent layers, especially the quantum dot light-emitting layer and the adjacent The compatibility problem between the electron transport layer (especially the zinc oxide layer) is more serious. The poorly compatible quantum dot light-emitting layer and the electronic functional layer (especially the zinc oxide layer) are prone to form a bulge at the interface, affecting the film-forming performance of the device, which in turn affects the light efficiency of the quantum dot light-emitting diode. One of the purposes of the embodiments of the present application is to provide a method for preparing quantum dot light-emitting diodes, quantum dot ink, which aims to solve the poor compatibility between the existing quantum dot light-emitting diode quantum dot light-emitting layers and adjacent layers , A problem affecting the light efficiency of quantum dot light-emitting diodes.

The technical solutions adopted in the embodiments of the present application are:

In the first aspect, a method for manufacturing a quantum dot light emitting diode is provided, including the following steps:

Provide quantum dot ink, the quantum dot ink includes a solvent system and quantum dots dispersed in the solvent system, wherein the solvent system includes a non-polar solvent and a doping compound;

Provide a cathode substrate or an anode substrate, deposit the quantum dot ink on the cathode substrate or the anode substrate, perform a light treatment, and prepare a quantum dot light-emitting layer by annealing, wherein the doping compound is energy after light treatment Photolysis into ionic compounds.

In one embodiment, the doping compound is selected from at least one of diphenyliodonium compounds and 1,2,3,4-thitriazole-5-mercapto salt compounds.

In one embodiment, the diphenyl iodonium compound is selected from at least one of (Ph ₂ I) ₄ Sn ₂ S ₆ , (Ph ₂ I) ₂ CdCl ₄ and (Ph ₂ I) ₂ MoO ₄ .

In one embodiment, the 1,2,3,4-thitriazole-5-mercapto salt compound is selected from at least one of NH ₄ CS ₂ N ₃ , NaCS ₂ N ₃ and LiCS ₂ N ₃ .

In one embodiment, based on the total weight of the solvent system being 100%, the mass percentage of the doping compound is 0%-10%, but not 0.

In one embodiment, the light source for the light treatment application is selected from ultraviolet light with a wavelength of 100-400 nm and/or visible light with a wavelength of 400-500 nm; and/or

The illumination treatment application light source has an illumination of 2000 lx-10000 lx; and/or

The time for performing the light treatment after depositing the quantum dot ink on the cathode substrate or the anode substrate is 10 minutes to 60 minutes.

In one embodiment, the non-polar solvent is selected from toluene, n-heptane, n-hexane, chloroform, methylene chloride, cyclohexane, and trichloroethylene.

In one embodiment, based on the total weight of the ink as 100%, the quantum dot ink, the mass percentage content of the quantum dot in the quantum dot ink is 0.05wt%-60wt%, the The non-polar solvent accounts for 35%-99.9% by weight of the quantum dot ink, and the doping compound accounts for 0.001%-10% by weight of the quantum dot ink.

In one embodiment, based on the total weight of the ink as 100%, the quantum dot ink has a quantum dot content of 0.5% to 20% by weight of the quantum dot ink. The non-polar solvent accounts for 70% to 99% by weight of the quantum dot ink, and the doping compound accounts for 0.003% to 3% by weight of the quantum dot ink.

In one embodiment, based on the total weight of the ink as 100%, in the quantum dot ink, the mass content of the quantum dot in the quantum dot ink is 1wt%-10wt%, the non- The polar solvent accounts for 80% to 98% by weight of the quantum dot ink, and the hetero compound accounts for 0.005% to 2% by weight of the quantum dot ink.

In a second aspect, an ink is provided, characterized in that the quantum dot ink includes a solvent system and quantum dots dispersed in the solvent system, wherein the solvent system includes a non-polar solvent and a doping compound, wherein, The doping compound is a compound that can be photolyzed into ions after being treated with light.

In one embodiment, the quantum dot ink is composed of the quantum dot, the non-polar solvent, and the doping compound.

In one embodiment, the diphenyl iodonium compound is selected from at least one of (Ph ₂ I) ₄ Sn ₂ S ₆ , (Ph ₂ I) ₂ CdCl ₄ and (Ph ₂ I) ₂ MoO ₄ ;and / or

The 1,2,3,4-thitriazole-5-mercapto salt compound is selected from at least one of NH ₄ CS ₂ N ₃ , NaCS ₂ N ₃ and LiCS ₂ N ₃ .

In one embodiment, based on the total weight of the solvent system as 100% and the total weight of the ink as 100%, the quantum dot content of the quantum dot ink is 0.5 wt% -20wt%, the non-polar solvent accounts for 70wt%-99wt% of the quantum dot ink, and the doping compound accounts for 0.003wt%-3wt of the quantum dot ink %.

The beneficial effect of the preparation method of the quantum dot light emitting diode provided by the embodiment of the present application is that the provided quantum dot ink contains a light-sensitive doping compound, and the quantum dot ink is deposited on the substrate and then subjected to light treatment. The doping compound changes under light conditions and can be converted into ions, so that the contact angle of the quantum dot ink deposited on the substrate surface becomes smaller, and the surface film layer of the quantum dot light-emitting layer formed on the substrate surface is smoother, and Improve the compatibility between the quantum dot light-emitting layer and the adjacent layer, and improve the light efficiency of the quantum dot light-emitting diode.

BRIEF DESCRIPTION

In order to more clearly explain the technical solutions in the embodiments of the present application, the following will briefly introduce the drawings required in the embodiments or exemplary technical descriptions. Obviously, the drawings in the following description are only for the application For some embodiments, for those of ordinary skill in the art, without paying any creative work, other drawings may be obtained based on these drawings.

FIG. 1 is a schematic flowchart of a method for manufacturing a quantum dot light-emitting diode according to an embodiment of the present application.

detailed description

In order to make the purpose, technical solutions and advantages of the present application more clear, the following describes the present application in further detail with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are only used to explain the present application, and are not used to limit the present application.

It should be understood that the terms “first” and “second” are used for description purposes only, and cannot be understood as indicating or implying relative importance or implicitly indicating the number of technical features indicated. Thus, the features defined as "first" and "second" may explicitly or implicitly include one or more of the features. In the description of this application, the meaning of "plurality" is two or more, unless otherwise specifically limited.

In order to explain the technical solutions described in this application, the following detailed description will be made in conjunction with specific drawings and embodiments.

As shown in FIG. 1, some embodiments of the present application provide a method for manufacturing a quantum dot light-emitting diode, including the following steps:

S10. Provide quantum dot ink, the quantum dot ink includes a solvent system and quantum dots dispersed in the solvent system, wherein the solvent system includes a non-polar solvent and a doping compound;

S20. Providing a cathode substrate or an anode substrate, depositing the quantum dot ink on the cathode substrate or the anode substrate, and then performing a light treatment, and annealing to prepare a quantum dot light-emitting layer, wherein the doping compound is light-treated Compounds that can be photolyzed into ions.

The preparation method of the quantum dot light emitting diode provided in the embodiment of the present application, the provided quantum dot ink contains a light-sensitive doping compound, and the quantum dot ink is deposited on the substrate and then subjected to light treatment. The doping compound changes under light conditions, and can be converted into ions, so that the contact angle of the quantum dot ink deposited on the surface of the substrate becomes smaller, and the surface film layer of the quantum dot light-emitting layer formed on the surface of the substrate is smoother, thereby improving The compatibility between the quantum dot light emitting layer and the adjacent layer improves the light efficiency of the quantum dot light emitting diode.

Specifically, in the above step S10, the quantum dot ink includes a solvent system and quantum dots dispersed in the solvent system, wherein the quantum dots are conventional quantum dots in the art, and the surface of the quantum dots usually contains organic body. In the examples of the present application, the solvent system for dispersing quantum dots includes conventional non-polar solvents, and the non-polar solvents are non-polar solvents, including toluene, n-heptane, n-hexane, chloroform, and methylene chloride , Cyclohexane and trichloroethylene, but not limited to this. On this basis, some doping compounds are also added to the solvent system. After the light treatment, the polarity of the solvent system is improved, because the doping compound can be converted into ions after the light treatment, which is a more polar ion than the doping compound, thereby reducing the surface of the quantum dot ink substrate The contact angle forms a flat and uniform film layer, which ultimately improves the light efficiency of the quantum dot light-emitting diode.

In some embodiments, the doping compound is selected from at least one of diphenyliodonium-based compounds and 1,2,3,4-thitriazole-5-mercapto salt-based compounds. As shown in the following reaction formula, the diphenyliodonium compounds, 1,2,3,4-thitriazole-5-mercapto salt compounds can be converted into substances with enhanced polarity under light conditions, reducing The contact angle of the small quantum dot ink on the surface of the underlying film layer such as the electron transport layer improves the flatness of the film layer, and the converted substance does not interfere with the light emission of the quantum dot light-emitting diode.

In some embodiments, the diphenyl iodonium compound is selected from at least one of (Ph ₂ I) ₄ Sn ₂ S ₆ , (Ph ₂ I) ₂ CdCl ₄ , (Ph ₂ I) ₂ MoO ₄ . In some embodiments, the 1,2,3,4-thitriazole-5-mercapto salt compound is selected from at least one of NH ₄ CS ₂ N ₃ , NaCS ₂ N ₃ , and LiCS ₂ N ₃ . The specific doping compound types listed in the above embodiments can significantly reduce the contact angle of the quantum dot ink on the surface of the electron transport layer, improve the flatness of the film layer, and thus improve the light efficiency of the quantum dot light emitting diode.

In the embodiment of the present application, a small amount of doping compound is added to the quantum dot ink, and after light treatment, the effect of reducing the contact angle of the quantum dot ink on the surface of the lower electron transport layer can be achieved. Based on the total weight of the solvent system being 100%, the mass percentage content of the doping compound is 0-10%, but not 0. Since the substance formed after the conversion of the doping compound will remain in the quantum dot light-emitting layer, when the mass percentage of the doping compound exceeds 10%, the impurity content in the quantum dot light-emitting layer increases, which reduces the quantum The light effect of the point light emitting layer. Based on the total weight of the ink being 100%, in some embodiments, in the quantum dot ink, the mass percentage content of the quantum dot in the quantum dot ink is 0.05wt%-60wt%, The non-polar solvent accounts for 35%-99.9% by weight of the quantum dot ink, and the doping compound accounts for 0.001%-10% by weight of the quantum dot ink. In some embodiments, the quantum dot content of the quantum dot ink is 0.5wt%-20wt%, and the non-polar solvent mass content of the quantum dot ink is 70wt%- 99wt%, the mass percentage content of the doping compound in the quantum dot ink is 0.003wt%-3wt%. In some embodiments, the content of quantum dots in the quantum dot ink is 1wt%-10wt%, and the percentage of non-polar solvents in the quantum dot ink is 80wt%-98wt%, The content of the hetero compound in the quantum dot ink is 0.005 wt% to 2 wt%.

In the above step S20, a substrate provided with a cathode or an anode is provided for depositing quantum dot ink. The selection of the substrate is not strictly limited, and a rigid substrate such as a glass substrate may be used; a flexible substrate such as a polyimide substrate or a polynorbornene substrate may also be used, but it is not limited thereto.

In some embodiments, the anode substrate is a substrate provided with an anode. The anode can be selected from conventional anode materials for light-emitting diodes. In a specific embodiment, the anode may use ITO, but it is not limited thereto.

In some embodiments, the anode substrate is a substrate provided with a cathode. The cathode can be selected from conventional cathode materials for light-emitting diodes. In some embodiments, the cathode may use metal electrodes, including but not limited to silver electrodes and aluminum electrodes. The thickness of the cathode is 60-120 nm, and in some embodiments of the present application is 100 nm.

The embodiment of the present application deposits the quantum dot ink on the substrate, specifically, deposits the quantum dot ink on the surface of the substrate. In some embodiments of the present application, the inkjet printing method is used to deposit the quantum dot ink on the substrate. The quantum dot ink can form a pre-made quantum dot light emitting layer on the surface of the electron transport layer. In some embodiments of the present application, the quantum dot ink is deposited on the cathode substrate or the anode substrate, followed by light treatment, and annealing to prepare a quantum dot light-emitting layer, so that the doping compound in the quantum dot ink is Changes under light conditions can be converted into ions, thereby adjusting the polarity of the solvent system in the quantum dot ink, reducing the contact angle of the quantum dot ink on the surface of the underlying film layer, such as the electron transport layer, improving the flatness of the film, thereby improving Light effect of quantum dot light emitting diode.

In some embodiments, the light source for the light treatment application is selected from ultraviolet light with a wavelength of 100-400 nm and/or visible light with a wavelength of 400-500 nm. Under ultraviolet and/or visible light irradiation conditions, the light-sensitive doping compound undergoes chemical changes and is converted into a more polar substance, thereby facilitating the spreading on the surface of the more polar underlying film layer such as the electron transport layer, The contact angle of the quantum dot ink on the surface of the electron transport layer is reduced, and the flatness of the quantum dot light emitting diode film layer is improved. In some embodiments of the present application, the light source used in the light treatment is selected from ultraviolet light with a wavelength of 100-400 nm, which is more conducive to the conversion of the doping compound into a more polar substance.

In the embodiment of the present application, the light intensity has a certain influence on the functional layer of the quantum dot light emitting diode. In some embodiments, under the condition that the light source applied by the light treatment has an illuminance of 500 lx to 50,000 lx, the pre-made quantum dot light-emitting layer is subjected to light treatment. If the illuminance is too high, it will have a certain impact on the formed functional materials such as quantum dot light-emitting materials, electron transport layers, etc., reducing the service life of the quantum dot light-emitting diode; if the illuminance is too low, the doped compound is converted The effect is not obvious. In some embodiments of the present application, the light treatment of the prefabricated quantum dot light-emitting layer is performed under the condition that the light source of the light treatment application has an illumination of 2000 lx-10000 lx.

On this basis, the irradiation time of the pre-made quantum dot light-emitting layer is 10 minutes to 60 minutes, which can reduce the contact angle of the quantum dot ink on the surface of the electron transport layer. The time of the light treatment is adjusted according to the change of the light intensity. The stronger the light intensity, the shorter the light processing time; the weaker the light intensity, the longer the light processing time.

The pre-made quantum dot light-emitting layer after the light treatment is subjected to annealing treatment, and the annealing method is performed according to a conventional method in the art to prepare a quantum dot light-emitting layer. In some embodiments, the thickness of the quantum dot light-emitting layer is 30-50 nm.

In some embodiments, in step S20, when an anode is provided on the substrate to form an anode substrate; in some embodiments, the anode substrate includes an anode provided on the substrate, and the anode surface is also provided with an empty A hole functional layer, the hole functional layer includes at least one of a hole injection layer, a hole transport layer, and an electron blocking layer. Among them, the hole injection layer and the hole transport layer are used to reduce the difficulty of hole injection, and the electron blocking layer is used to block excess electrons so that the excess electrons cannot reach the anode to form a leakage current, thereby improving the quantum dot light-emitting diode Current efficiency. Wherein, the material of the hole injection layer can be a conventional hole injection material, including but not limited to PEDOT:PSS. The material of the hole transport layer may use conventional hole transport materials, including but not limited to organic materials such as NPB and TFB, and inorganic materials such as NiO and MoO ₃ and their composites, and the thickness of the hole transport layer is 10-100nm.

In some embodiments, in step S20, a cathode substrate is formed when the cathode is disposed on the substrate; in some embodiments, the cathode substrate includes a cathode disposed on the substrate, and the cathode surface is also provided with electronic functions Layer, the electron functional layer includes at least one of an electron injection layer, an electron transport layer, and a hole blocking layer. Among them, the electron injection layer and the electron transport layer are used to reduce the difficulty of electron injection, and the hole blocking layer is used to block excess holes, so that the excess holes cannot reach the cathode to form a leakage current, thereby improving the quantum dot light-emitting diode Current efficiency. Wherein, the material of the electron injection layer may use conventional electron hole injection materials, including but not limited to LiF and CsF, and the thickness of the electron transport layer is 10-100 nm. The material of the electron transport layer may be a conventional electron transport material, including but not limited to n-type zinc oxide, and the thickness of the electron transport layer is 10-100 nm.

In some embodiments, in step S20, when the cathode is disposed on the substrate to form the cathode substrate, after preparing the quantum dot light-emitting layer, and before preparing the anode, further including the quantum dot light-emitting layer facing away from the cathode The step of preparing the hole functional layer on one side. The hole functional layer includes at least one of a hole injection layer, a hole transport layer, and an electron blocking layer. In some embodiments of the present application, when the cathode is provided on the substrate to form the cathode substrate, after preparing the quantum dot light-emitting layer and before preparing the anode, the method further includes: a side of the quantum dot light-emitting layer facing away from the cathode A hole transport layer is prepared, and a hole injection layer is prepared on the side of the hole transport layer facing away from the cathode.

For the preparation of the aforementioned electronic functional layer and hole functional layer, refer to the conventional methods in the art. In some embodiments of the present application, the solution processing method is used for preparation.

Embodiments of the present application also provide a quantum dot ink. The quantum dot ink includes a solvent system and quantum dots dispersed in the solvent system, wherein the quantum dots are conventional quantum dots in the art, and the surface of the quantum dots usually contains organic ligands. In the examples of the present application, the solvent system used to disperse the quantum dots includes conventional non-polar solvents, which are non-polar solvents, including but not limited to toluene, n-heptane, n-hexane, chloroform, Dichloromethane, cyclohexane, trichloroethylene, etc. but not limited thereto. On this basis, some doping compounds are also added to the solvent system. After the light treatment, the polarity of the solvent system is improved, because the doping compound can be converted into ions after the light treatment, thereby reducing the contact angle of the surface of the quantum dot ink substrate, forming a flat and uniform film layer, and finally improving the quantum Point light-emitting diode light effect.

In some embodiments, the doping compound is selected from at least one of diphenyliodonium-based compounds and 1,2,3,4-thitriazole-5-mercapto salt-based compounds. The diphenyliodonium compounds, 1,2,3,4-thitriazole-5-mercapto salt compounds can be converted into substances with enhanced polarity under light conditions, reducing the quantum dot ink in the underlying film The contact angle of the surface of the layer such as the electron transport layer improves the flatness of the film layer, and the converted substance does not interfere with the light emission of the quantum dot light-emitting diode.

In the embodiment of the present application, a small amount of doping compound is added to the quantum dot ink, and after light treatment, the effect of reducing the contact angle of the quantum dot ink on the surface of the lower electron transport layer can be achieved. Based on the total weight of the solvent system being 100%, the mass percentage content of the doping compound is 0-10%, but not 0. Since the substance formed after the conversion of the doping compound will remain in the quantum dot light-emitting layer, when the mass percentage of the doping compound exceeds 10%, the impurity content in the quantum dot light-emitting layer increases, which reduces the quantum The light effect of the point light emitting layer. In some examples of the present application, based on the total weight of the solvent system being 100%, the mass percentage content of the doping compound is 0.1-2%. In some embodiments, in the quantum dot ink, the mass content of the quantum dot in the quantum dot ink is 0.05wt%-60wt%, and the non-polar solvent accounts for the mass of the quantum dot ink The percentage content is 35wt%-99.9wt%, and the mass percentage content of the doping compound in the quantum dot ink is 0.001wt%-10wt%. In some embodiments, the quantum dot content of the quantum dot ink is 0.5wt%-20wt%, and the non-polar solvent mass content of the quantum dot ink is 70wt%- 99% by weight, the content percentage of the doping compound in the quantum dot ink is 0.003% to 3% by weight. In some embodiments, the content of quantum dots in the quantum dot ink is 1wt%-10wt%, and the percentage of non-polar solvents in the quantum dot ink is 80wt%-98wt%, The content of the hetero compound in the quantum dot ink is 0.005 wt% to 2 wt%.

The following is a description with reference to specific embodiments.

Example 1

A preparation method of quantum dot light-emitting diode includes the following steps:

S11. Provide quantum dots (CdSe/ZnS QDs) and a solvent system, disperse the quantum dots in the solvent system and configure the quantum dot ink, wherein the solvent system is (Ph ₂ I) ₂ MoO ₄ mass percentage content is 0.01% (Ph ₂ I) ₂ MoO ₄ n-hexane solution;

S12. Provide a cathode substrate (a metal aluminum electrode provided on a glass substrate), prepare an electron injection layer (LiF) on the cathode substrate, and prepare an electron transport layer (ZnO) on the electron injection layer;

S13. Depositing quantum dot ink on the surface of the electron transport layer to form a prefabricated quantum dot light-emitting layer; performing light treatment on the prefabricated quantum dot light-emitting layer and annealing to prepare a quantum dot light-emitting layer, wherein the light source used in the light treatment is selected Self-emitted ultraviolet light with a wavelength of 250nm;

S14. A hole transport layer (TFB) is prepared on the surface of the quantum dot light emitting layer facing away from the substrate, a hole injection layer (PEDOT:PSS) is prepared on the hole transport layer, and an anode is prepared on the hole injection layer (SED) ITO) to obtain quantum dot light-emitting diodes.

Comparative Example 1

D11. Provide CdSe/ZnS QDs ink without (Ph ₂ I) ₂ MoO ₄ added;

D12. Provide a cathode substrate (a metal aluminum electrode provided on a glass substrate), prepare an electron injection layer (LiF) on the cathode substrate, and prepare an electron transport layer (ZnO) on the electron injection layer;

D13. Deposit quantum dot ink on the surface of the electron transport layer to form a prefabricated quantum dot light-emitting layer; perform light treatment on the prefabricated quantum dot light-emitting layer and anneal to prepare a quantum dot light-emitting layer, wherein the light source used in the light treatment is selected Self-emitted ultraviolet light with a wavelength of 250nm;

D14. Prepare a hole transport layer (TFB) on the surface of the quantum dot light-emitting layer facing away from the substrate, prepare a hole injection layer (PEDOT:PSS) on the hole transport layer, and prepare an anode on the hole injection layer ( ITO) to obtain quantum dot light-emitting diodes.

Table 1

Example 2-5

S21. Provide quantum dots (CdSe/ZnS QDs) and a solvent system, disperse the quantum dots in the solvent system to configure the quantum dot ink, wherein the solvent system includes a non-polar solvent and a doping compound, and the doping compound is A modified solvent with enhanced polarity after light treatment. In Example 2, the doping compound is (Ph ₂ I) ₂ CdCl ₄ ; in Example 3, the doping compound is (Ph ₂ I) ₂ MoO ₄ ; in Example 4, the doping compound is LiCS ₂ N ₃ ; In Example 5, the doping compound is NH ₄ CS ₂ N ₃ ;

S22. Provide a cathode substrate (a metal aluminum electrode provided on a glass substrate), prepare an electron injection layer (LiF) on the cathode substrate, and prepare an electron transport layer (ZnO) on the electron injection layer;

S23. Depositing quantum dot ink on the surface of the electron transport layer to form a prefabricated quantum dot light-emitting layer; performing light treatment on the prefabricated quantum dot light-emitting layer and annealing to prepare a quantum dot light-emitting layer, wherein the light source used in the light treatment is selected Self-emitted ultraviolet light with a wavelength of 250nm;

S24. A hole transport layer (TFB) is prepared on the surface of the quantum dot light emitting layer facing away from the substrate, a hole injection layer (PEDOT: PSS) is prepared on the hole transport layer, and an anode is prepared on the hole injection layer (SED) ITO) to obtain quantum dot light-emitting diodes.

Comparative Example 2

D21. Disperse quantum dots in the same non-polar solvent as in Example 2-5 to configure quantum dot ink;

D22. Provide a cathode substrate (a metal aluminum electrode provided on a glass substrate), prepare an electron injection layer (LiF) on the cathode substrate, and prepare an electron transport layer (ZnO) on the electron injection layer;

D23. Depositing quantum dot ink on the surface of the electron transport layer, annealing to prepare a quantum dot light emitting layer;

D24. A hole transport layer (TFB) is prepared on the surface of the quantum dot light-emitting layer facing away from the substrate, a hole injection layer (PEDOT:PSS) is prepared on the hole transport layer, and an anode is prepared on the hole injection layer ( ITO) to obtain quantum dot light-emitting diodes.

The quantum dot light-emitting diode prepared by adding no doping compound to the quantum dot ink of Comparative Example 2 and the quantum dot light-emitting diode prepared by adding the doping compound to the quantum dot ink of Example 2-5 were tested respectively. The EQE change of the quantum dot light-emitting diode (%) is shown in Table 2 below.

Table 2

It can be seen from Table 2 that the quantum dot light-emitting diode prepared by adding a doping compound to the quantum dot ink has significantly improved EQE during the aging process. The quantum dot light-emitting diodes prepared by adding doping compounds to quantum dot inks have improved luminous efficiency to varying degrees. Among them, quantum dot light-emitting diodes containing (Ph ₂ I) ₂ MoO ₄ components have the best external quantum efficiency and the best luminescence effectiveness.

The above are only optional embodiments of the present application, and are not intended to limit the present application. For those skilled in the art, the present application may have various modifications and changes. Any modification, equivalent replacement, improvement, etc. within the spirit and principle of this application should be included in the scope of the claims of this application.

Claims

The preparation method of quantum dot light-emitting diode is characterized in that it includes the following steps:

Provide quantum dot ink, the quantum dot ink includes a solvent system and quantum dots dispersed in the solvent system, wherein the solvent system includes a non-polar solvent and a doping compound;

Provide a cathode substrate or an anode substrate, deposit the quantum dot ink on the cathode substrate or the anode substrate, and perform light treatment, annealing to prepare a quantum dot light-emitting layer, and annealing to obtain a quantum dot light-emitting layer, wherein the doping The hetero compound is a compound that can be photolyzed into ions after being treated with light.
The method for preparing a quantum dot light emitting diode according to claim 1, wherein the doping compound is selected from diphenyliodonium compounds and 1,2,3,4-thitriazole-5-mercapto salt At least one kind of compound.
The method for preparing a quantum dot light emitting diode according to claim 2, wherein the diphenyl iodonium compound is selected from (Ph 2 I) 4 Sn 2 S 6 , (Ph 2 I) 2 CdCl 4 and (Ph 2 I) At least one of 2 MoO 4 .
The method for preparing a quantum dot light-emitting diode according to claim 2, wherein the 1,2,3,4-thitriazole-5-mercapto salt compound is selected from NH 4 CS 2 N 3 and NaCS 2 At least one of N 3 and LiCS 2 N 3 .
The method for preparing a quantum dot light-emitting diode according to claim 1, characterized in that, based on the total weight of the solvent system is 100%, the mass percentage content of the doping compound is 0%-10%, but Not 0.
The method for preparing a quantum dot light emitting diode according to any one of claims 1 to 5, wherein the light source used in the light treatment is selected from ultraviolet light with a wavelength of emitted light of 100-400 nm and/or the wavelength of the emitted light is 400-500nm visible light.
The method for preparing a quantum dot light emitting diode according to any one of claims 1 to 5, wherein the illumination treatment application light source has an illuminance of 2000 lx-10000 lx.
The method for preparing a quantum dot light-emitting diode according to any one of claims 1 to 5, wherein the time for performing the light treatment after depositing the quantum dot ink on the cathode substrate or the anode substrate is 10 minutes -60 minutes.
The method for preparing a quantum dot light emitting diode according to any one of claims 1 to 5, wherein the non-polar solvent is selected from toluene, n-heptane, n-hexane, chloroform, methylene chloride, and cyclohexane And trichloroethylene.
The method for preparing a quantum dot light-emitting diode according to any one of claims 1 to 5, characterized in that, based on the total weight of the ink as 100%, in the quantum dot ink, the quantum dot accounts for the The mass percentage content of the quantum dot ink is 0.05wt%-60wt%, the non-polar solvent accounts for the mass percentage content of the quantum dot ink is 35wt%-99.9wt%, the doping compound accounts for the quantum The mass percentage content of dot ink is 0.001wt%-10wt%.
The method for preparing a quantum dot light-emitting diode according to claim 10, characterized in that, based on the total weight of the ink is 100%, in the quantum dot ink, the quantum dot accounts for the mass of the quantum dot ink The percentage content is 0.5wt%-20wt%, the non-polar solvent accounts for 70%-99wt% of the mass content of the quantum dot ink, the doping compound accounts for the mass percentage of the quantum dot ink The content is 0.003wt%-3wt%.
The method for preparing a quantum dot light-emitting diode according to claim 11, characterized in that, based on the total weight of the ink is 100%, in the quantum dot ink, the quantum dot accounts for the mass of the quantum dot ink The percentage content is 1wt%-10wt%, the non-polar solvent accounts for 80%-98wt% of the mass content of the quantum dot ink, and the hetero compound accounts for the mass percentage of the quantum dot ink is 0.005wt%-2wt%.
An ink, characterized in that the ink includes a solvent system and quantum dots dispersed in the solvent system, wherein the solvent system includes a non-polar solvent and a doping compound, wherein the doping compound is illuminated A compound that can be photolyzed into ions after treatment.
The ink according to claim 13, wherein the ink is composed of the quantum dots, the non-polar solvent, and the doping compound.
The ink according to claim 13 or 14, wherein the doping compound is selected from the group consisting of diphenyl iodonium compounds and 1,2,3,4-thitriazole-5-mercapto salt compounds At least one.
The ink according to claim 13 or 14, wherein the diphenyliodonium compound is selected from (Ph 2 I) 4 Sn 2 S 6 , (Ph 2 I) 2 CdCl 4 and (Ph 2 I ) 2 MoO 4 at least one.
The ink according to claim 13 or 14, wherein the 1,2,3,4-thitriazole-5-mercapto salt compound is selected from NH 4 CS 2 N 3 , NaCS 2 N 3 and LiCS 2 At least one of N 3 .
The ink according to claim 13 or 14, wherein the total weight of the solvent system is 100%, and the total weight of the ink is 100%, the quantum dots occupy the quantum dot ink The mass percentage content is 0.5wt%-20wt%, the non-polar solvent accounts for the mass percentage content of the quantum dot ink is 70wt%-99wt%, the doping compound accounts for the mass of the quantum dot ink The percentage content is 0.003wt%-3wt%.