Light emitting diode device based on quantum dots and preparation method thereof

Abstract

The invention relates to a light emitting diode device based on quantum dots and a preparation method thereof, and belongs to the technical field of semiconductor devices. The light-emitting diode device based on the quantum dots comprises a light-emitting layer, the materials of the light-emitting layer comprise colloidal quantum dots and an organic light-emitting material; the mass ratio of the colloidal quantum dots to the organic light-emitting material is 100: (0.1-20); and the distribution gap of the colloidal quantum dots is larger than the unit cell size of the organic light-emitting material. By selecting proper colloidal quantum dots and organic light-emitting materials for compounding, dot gap defects are reduced, non-radiative recombination is inhibited, the structure of a functional layer of a device is optimized, and the carrier injection efficiency is improved, so that the photoelectric property of a colloidal quantum dot light-emitting layer is improved.

Description

Technical Field

[0001] The present invention belongs to the technical field of semiconductor devices, and in particular relates to a quantum dot-based light emitting diode device and a preparation method thereof. Background Art

[0002] In recent years, light-emitting diode technology has been widely used in lighting, display, and communication. Traditional light-emitting diode technology is mainly based on III-V compound semiconductor materials, such as gallium nitride and gallium arsenide. The light-emitting diodes made of these materials have high brightness and stability. However, traditional light-emitting diodes have certain limitations in terms of light color purity, frequency range, and manufacturing cost.

[0003] Quantum dots are a type of semiconductor material with nanoscale dimensions. Their unique electronic and optical properties make them ideal materials for the new generation of optoelectronic devices. The energy level structure of quantum dots is determined by their size. Therefore, by controlling the size of quantum dots, their emission wavelength can be adjusted to achieve full spectrum emission from ultraviolet to visible light to infrared. Quantum dots have the advantages of high brightness, high color purity, and tunable emission wavelength. Compared with traditional semiconductor materials, these properties of quantum dots have shown great application prospects in the field of optoelectronic devices.

[0004] Quantum dot-based light-emitting diodes are devices that combine the excellent optical properties of quantum dots with the electroluminescent properties of traditional light-emitting diodes. Quantum dot light-emitting diodes can significantly improve the color purity and luminous efficiency of the device by embedding quantum dot materials into the light-emitting layer. At present, quantum dot light-emitting diode technology has made initial progress in high color gamut display, flexible display and wearable devices. However, the existing quantum dot light-emitting diode technology still has some challenges in the design of device structure, preparation of light-emitting layer and interface stability, which limits its further development and application. Surface defects form non-radiative recombination centers, reduce the photoluminescence quantum yield, and insufficient carrier mobility leads to reduced exciton recombination efficiency and affects device stability. In addition, the sensitivity of film thickness to performance makes process control more complicated. Therefore, optimizing quantum dot surface defects, improving carrier mobility and reducing film thickness dependence are key technical difficulties in preparing efficient and stable quantum dot-based light-emitting diodes.

[0005] Therefore, designing and preparing an efficient and stable quantum dot-based light-emitting diode device and optimizing its preparation process are of great significance for the commercial application of high-performance quantum dot light-emitting diodes. By improving the synthesis method of quantum dots, optimizing the layer structure design of the device, and improving the interface stability, the luminescence performance and service life of quantum dot light-emitting diodes can be effectively improved, thereby promoting its development in a wider range of application fields. Summary of the invention

[0006] To this end, the technical problem to be solved by the present invention is to overcome the fact that quantum dot light-emitting layer films in the prior art often have point gaps and surface defects, thereby forming defect centers. Carrier quenching will significantly increase the probability of non-radiative recombination, resulting in a decrease in luminous efficiency and seriously affecting the long-term stability of the device.

[0007] In order to solve the above technical problems, the present invention provides a quantum dot-based light-emitting diode device and a preparation method thereof. Through the effective doping of organic light-emitting materials, the luminescence efficiency of colloidal quantum dots is improved, the point defects in the quantum dot film are filled, and new radiation recombination centers are formed, which effectively reduces non-radiative recombination pathways and significantly enhances the overall performance of the device.

[0008] A first object of the present invention is to provide a quantum dot-based light-emitting diode device, comprising a light-emitting layer; The material of the light-emitting layer includes colloidal quantum dots and organic light-emitting materials; the mass ratio of the colloidal quantum dots to the organic light-emitting materials is 100:(0.1-20), and the organic light-emitting materials and the colloidal quantum dots can be uniformly mixed; In one embodiment of the present invention, the colloidal quantum dots are selected from one or more of zinc oxide quantum dots, gallium nitride quantum dots, calcium fluoride quantum dots, zinc sulfide quantum dots, cadmium sulfide quantum dots, cadmium selenide quantum dots, cadmium telluride quantum dots, indium phosphide quantum dots, lead sulfide quantum dots, lead selenide quantum dots, lead telluride quantum dots, mercury telluride quantum dots, silver sulfide quantum dots, silver selenide quantum dots, silver telluride quantum dots and indium arsenide quantum dots.

[0009] Furthermore, the colloidal quantum dots are lead sulfide quantum dots; and the preparation of the lead sulfide quantum dots comprises the following steps: The sulfur source is heated in a second organic solvent to react to obtain a sulfur precursor solution; The lead source and the surfactant are heated and reacted in a first organic solvent to obtain a lead precursor solution. Under a protective atmosphere, the sulfur precursor solution is added to the lead precursor solution for nucleation growth to obtain lead sulfide quantum dots.

[0010] In one embodiment of the present invention, the sulfur source is selected from one or more of hexamethyldisilathione, sulfur powder and dithioaminomethane.

[0011] In one embodiment of the present invention, the lead source is selected from one or more of lead acetate trihydrate, lead sulfate, lead oxide, lead chloride, lead bromide and lead iodide; the surfactant is selected from oleic acid and / or oleylamine; which can help control the growth, stability and optical properties of quantum dots.

[0012] In one embodiment of the present invention, the first organic solvent and the second organic solvent are independently selected from one or more of hexadecene, octadecene and eicosene; the solvent can also serve as a heat transfer medium to help promote the decomposition of the lead sulfide precursor and the growth of quantum dots under heating conditions.

[0013] In one embodiment of the present invention, the distribution gap of the colloidal quantum dots is larger than the unit cell size of the organic light-emitting material; the organic light-emitting material can be filled and doped into the gap of the colloidal quantum dots, thereby avoiding carrier quenching, promoting efficient utilization of excitons, and ensuring high efficiency and operational stability of the device.

[0014] In one embodiment of the present invention, the particle size of the colloidal quantum dots is 2 nm-3 nm; and the unit cell size of the organic light-emitting material is 5 Å-18 Å.

[0015] In one embodiment of the present invention, the organic light-emitting material is selected from fluorescent materials and / or phosphorescent materials; the fluorescent material is selected from traditional fluorescent materials and / or thermally activated delayed fluorescent materials.

[0016] Further, the fluorescent material is selected from one or more of 8-(4-(diphenylamino)phenyl)anthraquinone[1,2-b]pyrazine-2,3-dicarbonitrile, 8-(4-(di([1,1'-biphenyl]-4-yl)amino)phenyl)anthraquinone[1,2-b]pyrazine-2,3-dicarbonitrile, 3,4-bis(4-(diphenylamino)phenyl)acenaphtho[1,2-b]pyrazine-8,9-dicarbonitrile, 3-(4-(diphenylamino)phenyl)acenaphtho[1,2-b]pyrazine-8,9-dicarbonitrile and 3-(4-(diphenylamino)phenyl)acenaphtho[1,2-b]quinoxaline-8,9-dicarbonitrile.

[0017] Furthermore, the phosphorescent material is selected from one or more of bis(2-methyldibenzo[f,h]quinoxaline)(acetylacetonate)-iridium(III), bis(2-(2'-benzothienyl)pyridine)(acetylacetonate)iridium(III) and bis(1-phenylisoquinoline)(acetylacetonate)iridium(III).

[0018] In one embodiment of the present invention, the light emission peak of the organic light emitting material is in the ultraviolet-visible-infrared region.

[0019] In one embodiment of the present invention, the luminescence peak of the organic luminescent material is 780 nm-1000 nm, and the fluorescence quantum yield is more than 70%. The luminescence peak of the organic luminescent material and the absorption peak of the colloidal quantum dots have an overlapping part and can transfer energy. The organic luminescent material has an excellent fluorescence quantum yield and has the ability to efficiently generate excitons.

[0020] In one embodiment of the present invention, it further includes one or more of an anode, a hole injection layer, a hole transport layer, an electron transport layer, an electron injection layer and a cathode.

[0021] In one embodiment of the present invention, the material of the hole injection layer is selected from one or more of poly(3,4-ethylenedioxythiophene)-polystyrene sulfonic acid, nickel oxide and molybdenum oxide; The material of the hole transport layer is selected from one or more of poly[bis(4-phenyl)(4-butylphenyl)amine], poly(9-vinylcarbazole) and polytriphenylamine.

[0022] In one embodiment of the present invention, the material of the electron transport layer is selected from one or more of 2,4,6-tris[3-(diphenylphosphinoyl)phenyl]-1,3,5-triazole, 3,3'-[5'-[3-(3-pyridyl)phenyl][1,1':3',1''-terphenyl]-3,3''-diyl]bipyridine and 2,2',2''-(1,3,5-phenyl)triazine-3,3',3''-triylbenzene; The material of the electron injection layer is selected from one or more of 8-hydroxyquinoline-lithium, lithium fluoride and (tris(8-hydroxyquinoline)aluminum).

[0023] In one embodiment of the present invention, the material of the anode is selected from one or more of indium tin oxide, fluorine-doped tin oxide and silver; The material of the cathode is selected from silver and / or aluminum.

[0024] In one embodiment of the present invention, the thickness of the anode is 20 nm-60 nm; The thickness of the hole injection layer is 30 nm-80 nm; The thickness of the hole transport layer is 20 nm-50 nm; The thickness of the light-emitting layer is 30 nm-90 nm; The thickness of the electron transport layer is 20 nm-60 nm; The thickness of the electron injection layer is 1 nm-5 nm; The thickness of the cathode is 80 nm-200 nm.

[0025] The second object of the present invention is to provide a method for preparing a quantum dot-based light-emitting diode device, comprising the following steps: S1, sequentially preparing a hole injection layer and a hole transport layer on the anode by spin coating; S2, spin coating a composite solution on the hole transport layer to obtain a light-emitting layer; the composite solution includes a colloidal quantum dot solution and an organic light-emitting material solution; S3. Prepare an electron transport layer, an electron injection layer and a cathode in sequence on the surface of the light-emitting layer by vacuum evaporation to obtain the quantum dot-based light-emitting diode device.

[0026] In one embodiment of the present invention, in S2, the concentration of the colloidal quantum dot solution is 10 mg / mL-30 mg / mL; The concentration of the organic light-emitting material solution is 0.01 mg / mL-150 mg / mL.

[0027] In one embodiment of the present invention, in S2, the volume ratio of the colloidal quantum dot solution to the organic light-emitting material solution is 100:(0.5-5).

[0028] In one embodiment of the present invention, in S2, the colloidal quantum dot solution is prepared by dissolving the colloidal quantum dots in a first solvent; The organic light-emitting material solution is prepared by dissolving the organic light-emitting material in a second solvent.

[0029] In one embodiment of the present invention, the first solvent and the second solvent are independently selected from one or more of chlorobenzene, toluene, n-butane, n-hexane, n-octane, cyclobutane, cyclohexane and cyclooctane.

[0030] The technical solution of the present invention has the following advantages over the prior art: The quantum dot-based light-emitting diode device of the present invention reduces dot gap defects, inhibits non-radiative recombination, optimizes the device functional layer structure and improves carrier injection efficiency, thereby improving the photoelectric performance of the colloidal quantum dot light-emitting layer. The flatness and uniformity of the surface of the light-emitting layer are improved, and the overall performance of the quantum dot-based light-emitting diode device is significantly improved, which is conducive to reducing the leakage current of the device, improving the recombination efficiency of carriers, and thus improving the light-emitting life and efficiency of the quantum dot-based light-emitting diode device.

[0031] The preparation method of the present invention prepares a quantum dot-based light-emitting diode device by combining quantum dot surface and thin film dot gap defect passivation. The method is simple and convenient, the raw materials are easily obtained, the method is insensitive to thickness, and the method has high repeatability. The method is conducive to the preparation of large-area flexible devices and promotes the progress of large-scale industrialization. BRIEF DESCRIPTION OF THE DRAWINGS

[0032] In order to make the content of the present invention more clearly understood, the present invention is further described in detail below according to specific embodiments of the present invention in conjunction with the accompanying drawings, wherein: Figure 1 This is a schematic structural diagram of a quantum dot-based light-emitting diode device according to Example 1 of the present invention; Figure 2This is an electroluminescence spectrum diagram of a quantum dot-based light-emitting diode device according to Example 1 of the present invention; Figure 3 is a graph showing the relationship between current density and voltage of quantum dot-based light-emitting diode devices according to embodiments 1, 4, and 7 of the present invention; Figure 4 is a graph showing the relationship between the irradiation intensity and the voltage of the quantum dot-based light-emitting diode devices of Examples 2, 5, and 8 of the present invention; Figure 5 Graph showing the relationship between external quantum efficiency and current density of quantum dot-based light-emitting diode devices according to embodiments 3, 6, and 9 of the present invention; Figure 6 The figure is a relationship diagram between the operating life and time of the light emitting diode devices of Example 1 and Comparative Examples 1-4 of the present invention; Figure 7 This is a photograph of the quantum dot-based light-emitting diode device according to Example 1 of the present invention being lit up under an operating voltage; Figure 8 A diagram showing the light-emitting mechanism of a quantum dot-based light-emitting diode device of the present invention; Fig. 9 The diagram is a schematic diagram of energy transfer between the organic light-emitting material and lead sulfide quantum dots of the quantum dot-based light-emitting diode device of the present invention. DETAILED DESCRIPTION

[0033] The present invention is further described below in conjunction with specific embodiments so that those skilled in the art can better understand the present invention and implement it. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of them. It should be understood that the specific embodiments are only used to explain the present invention, but the embodiments are not intended to limit the present invention.

[0034] In the present invention, unless otherwise explained, technical and scientific terms used in the present invention have the same meanings as commonly understood by those skilled in the art to which the present invention belongs.

[0035] In the present invention, unless otherwise stated, the term "and / or" used in the present invention includes any and all combinations of one or more of the associated listed items.

[0036] In the present invention, unless otherwise stated, the experimental methods used in the embodiments of the present invention are conventional methods unless otherwise stated, and the materials, reagents, etc. used are all commercially available unless otherwise stated.

[0037] In the present invention, unless otherwise specified, the ITO glass used in the examples of the present invention is purchased from Lumitec LTD.

[0038] In the present invention, unless otherwise specified, lead acetate trihydrate, hexamethyldisilathioane, oleic acid, octadecene and n-hexane used in the examples of the present invention were purchased from Sigma-Aldrich Company.

[0039] In the present invention, unless otherwise specified, 2,4,6-tris[3-(diphenylphosphinoyl)phenyl]-1,3,5-triazole and 8-hydroxyquinoline-lithium used in the examples of the present invention were purchased from Xi'an Biolight Optoelectronics Technology Co., Ltd.

[0040] In the present invention, unless otherwise specified, the luminescence peak of 8-(4-(diphenylamino)phenyl)anthraquinone[1,2-b]pyrazine-2,3-dicarbonitrile used in the embodiments of the present invention is 782 nm, the fluorescence quantum yield is 71%, and the unit cell three-sided dimensions are approximately 8 × 8 × 18 Å.

[0041] In the present invention, unless otherwise specified, the luminescence peak of bis(2-methyldibenzo[f,h]quinoxaline)(acetylacetonate)-iridium(III) used in the embodiments of the present invention is 785 nm, the fluorescence quantum yield is 70%, and the unit cell three-sided dimensions are approximately 7 × 8 × 15 Å.

[0042] In the present invention, unless otherwise specified, the luminescence peak of 3,4-bis(4-(diphenylamino)phenyl)acenaphtho[1,2-b]pyrazine-8,9-dicarbonitrile used in the embodiments of the present invention is 780 nm, the fluorescence quantum yield is 73%, and the unit cell three-sided dimensions are approximately 5 × 5 × 16 Å.

[0043] In the present invention, unless otherwise specified, the luminescence peak of 2,4,5,6-tetrakis(9-carbazolyl)-isophthalonitrile used in the comparative examples of the present invention is 551 nm, the fluorescence quantum yield is more than 60%, and the unit cell three-sided dimensions are about 10 × 10 × 20 Å.

[0044] In the present invention, unless otherwise specified, the preparation of lead sulfide quantum dots used in the embodiments of the present invention specifically includes the following steps: hexamethyldisilathione and octadecene are mixed in a volume ratio of 1:9, heated to 100°C under vacuum and stirred for 2 h to obtain an anhydrous and oxygen-free sulfur precursor solution; oleic acid and octadecene are mixed in a mass ratio of 1:10, 10 mmol of lead acetate trihydrate is dissolved, heated to 100°C under vacuum and stirred for 2 h to obtain an anhydrous and oxygen-free lead precursor solution; under a nitrogen atmosphere, the sulfur precursor solution is quickly injected into the lead precursor solution (volume ratio of 1:1), and nucleation and growth are performed to obtain a lead sulfide quantum dot solution; after the reaction, the lead sulfide quantum dot solution is transferred to a glove box filled with nitrogen, an equal volume of isopropanol is added and centrifuged to purify the lead sulfide quantum dots; then the extracted lead sulfide quantum dots are redispersed in n-hexane, acetone is added to precipitate, and then centrifuged to obtain lead sulfide quantum dots with a particle size of 2 nm-3 nm. Example 1

[0045] Reference Figure 1 As shown, the quantum dot-based light-emitting diode device and the preparation method thereof of this embodiment specifically include the following steps: S1. Use a nanosponge dipped in a cleaning agent to scrub the ITO glass with a thickness of 50 nm and rinse it with deionized water. Put it in a beaker and put it in an ultrasonic water bath. Use ethanol, acetone and deionized water to ultrasonically clean it for 15 minutes and repeat it 3 times. After cleaning, put the beaker containing the ITO glass in a drying oven for heating and drying. Finally, place the ITO glass face up in a watch glass and treat it in a UV ozone cleaning machine for 15 minutes to obtain the pretreated ITO glass. S2, poly(3,4-ethylenedioxythiophene)-polystyrene sulfonic acid solution was filtered through a 0.45 μm filter head and spin-coated on ITO glass at a rotation speed of 5000 rpm for 60 s, and then annealed at 150 °C for 15 min to obtain a uniform hole injection layer with a thickness of 50 nm; S3, poly[bis(4-phenyl)(4-butylphenyl)amine] solution was filtered through a 0.22 μm filter and spin-coated on the hole injection layer at 4000 rpm for 50 s, and then annealed at 150 °C for 15 min to obtain a uniform hole transport layer with a thickness of 40 nm; S4, dissolving the lead sulfide quantum dot material in n-hexane to obtain a lead sulfide quantum dot solution with a concentration of 20 mg / mL; dissolving 8-(4-(diphenylamino)phenyl)anthraquinone[1,2-b]pyrazine-2,3-dicarbonitrile in n-hexane to obtain a 8-(4-(diphenylamino)phenyl)anthraquinone[1,2-b]pyrazine-2,3-dicarbonitrile solution with a concentration of 4 mg / mL; mixing the lead sulfide quantum dot solution and the 8-(4-(diphenylamino)phenyl)anthraquinone[1,2-b]pyrazine-2,3-dicarbonitrile solution at a volume ratio of 100:1 to obtain a composite solution, processing 50 μL of the composite solution on the hole transport layer at a rotation speed of 3000 rpm, and repeatedly stacking to obtain a uniform light-emitting layer with a thickness of 40 nm; S5. An electron transport layer, an electron injection layer and a cathode are obtained by vacuum evaporation. The materials are 2,4,6-tris[3-(diphenylphosphinoyl)phenyl]-1,3,5-triazole, 8-hydroxyquinoline-lithium and aluminum, respectively. The evaporation rates are 2 Å / s, 0.2 Å / s and 6 Å / s, respectively. The thicknesses are 60 nm, 2 nm and 100 nm, respectively. Thus, a quantum dot-based light-emitting diode device is obtained. Example 2

[0046] The method is basically the same as Example 1, except that the lead sulfide quantum dot material and 8-(4-(diphenylamino)phenyl)anthraquinone[1,2-b]pyrazine-2,3-dicarbonitrile are dissolved in n-hexane at a volume ratio of 100:2. Example 3

[0047] The method is basically the same as Example 1, except that the lead sulfide quantum dot material and 8-(4-(diphenylamino)phenyl)anthraquinone[1,2-b]pyrazine-2,3-dicarbonitrile are dissolved in n-hexane at a volume ratio of 100:3. Example 4

[0048] The method is basically the same as Example 1, except that the lead sulfide quantum dot material and bis(2-methyldibenzo[f,h]quinoxaline)(acetylacetonate)-iridium(III) are dissolved in n-hexane at a volume ratio of 100:1. Example 5

[0049] The method is basically the same as Example 1, except that the lead sulfide quantum dot material and bis(2-methyldibenzo[f,h]quinoxaline)(acetylacetonate)-iridium(III) are dissolved in n-hexane at a volume ratio of 100:2. Example 6

[0050] The method is basically the same as Example 1, except that the lead sulfide quantum dot material and bis(2-methyldibenzo[f,h]quinoxaline)(acetylacetonate)-iridium(III) are dissolved in n-hexane at a volume ratio of 100:3. Example 7

[0051] The method is basically the same as Example 1, except that the lead sulfide quantum dot material and 3,4-bis(4-(diphenylamino)phenyl)acenaphtho[1,2-b]pyrazine-8,9-dicarbonitrile are dissolved in n-hexane at a volume ratio of 100:1. Example 8

[0052] The method is basically the same as Example 1, except that the lead sulfide quantum dot material and 3,4-bis(4-(diphenylamino)phenyl)acenaphtho[1,2-b]pyrazine-8,9-dicarbonitrile are dissolved in n-hexane at a volume ratio of 100:2. Example 9

[0053] The method is basically the same as Example 1, except that the lead sulfide quantum dot material and 3,4-bis(4-(diphenylamino)phenyl)acenaphtho[1,2-b]pyrazine-8,9-dicarbonitrile are dissolved in n-hexane at a volume ratio of 100:3. Comparative Example 1

[0054] The method is basically the same as Example 1, except that 8-(4-(diphenylamino)phenyl)anthraquinone[1,2-b]pyrazine-2,3-dicarbonitrile is replaced by 2,4,5,6-tetrakis(9-carbazolyl)-isophthalonitrile. Comparative Example 2

[0055] The method is basically the same as Example 1, except that 8-(4-(diphenylamino)phenyl)anthraquinone[1,2-b]pyrazine-2,3-dicarbonitrile is not added. Comparative Example 3

[0056] The method is basically the same as Example 1, except that the lead sulfide quantum dots are replaced with cesium lead bromine quantum dots. Comparative Example 4

[0057] The method is basically the same as Example 1, except that the thickness of the light-emitting layer is 220 nm. Test Example 1

[0058] The light-emitting diode devices of Examples 1-9 and Comparative Examples 1-4 were subjected to electroluminescence testing by connecting a calibrated photon multi-channel PMA-12 analyzer system Hamamatsu C10027-01 (360 nm-950 nm) and C10028-01 (950 nm-1600 nm) to an integrating sphere for collecting the forward light of the device and a power supply system for controlling the current output point, using a PR-745 instrument Photo Research, calibrated absolute radiance at 380 nm-1060 nm.

[0059] The electroluminescence spectrum of the quantum dot-based light-emitting diode device of Example 1 is shown in FIG. Figure 2 As shown, from Figure 2 It can be seen that the electroluminescence peak of the quantum dot-based light-emitting diode device is located at 1010 nm, which is in the second near-infrared region. As the applied voltage increases, the electroluminescence peak remains stable.

[0060] The current density and voltage relationship diagram of the quantum dot-based light emitting diode devices of Examples 1, 4, and 7 are shown in FIG. Figure 3 As shown, from Figure 3 It can be seen that the turn-on voltage is about 2 V.

[0061] The relationship between the irradiation intensity and voltage of the quantum dot-based light-emitting diode devices of Examples 2, 5, and 8 is shown in the figure below: Figure 4 As shown, from Figure 4 It can be seen that the quantum dot-based light-emitting diode device achieves the highest irradiation intensity at 8 V, which is 0.78 Wsr -1 m -2 .

[0062] The relationship between the external quantum efficiency and current density of the quantum dot-based light-emitting diode devices of Examples 3, 6, and 9 is shown in the figure below: Figure 5 As shown, from Figure 5 It can be seen that the highest external quantum efficiency is 23.2%, which shows that excitons are transferred from organic fluorescent groups to quantum dots.

[0063] The relationship between the operating life and time of the light emitting diode devices of Example 1 and Comparative Examples 1-4 is shown in the figure below: Figure 6 As shown, from Figure 6 It can be seen that the operating lifespans of comparative examples 1-4 are 270 min, 340 min, 240 min and 47 min respectively, while the operating lifespan of the device in Example 1 is 500 min. It can be seen that this embodiment can effectively improve the operating stability of the device through efficient use of carriers.

[0064] The photo of the quantum dot-based light-emitting diode device of Example 1 lit up under the operating voltage is shown in FIG. Figure 7 As shown, from Figure 7 It can be seen that the light emitting surface of the device emits light evenly and there are no bad pixels.

[0065] The light emitting mechanism of the quantum dot-based light emitting diode device of the present invention is as follows Figure 8-Figure 9 As shown. Figure 8-Figure 9 It can be seen that organic light-emitting materials can be filled into the gaps of lead sulfide quantum dots, thereby avoiding carrier quenching, promoting the efficient utilization of excitons, and ensuring the high efficiency and operational stability of the device.

[0066] Obviously, the above embodiments are merely examples for clear explanation and are not intended to limit the implementation methods. For those skilled in the art, other different forms of changes or modifications can be made based on the above description. It is not necessary and impossible to list all the implementation methods here. The obvious changes or modifications derived from these are still within the protection scope of the invention.

Claims

1. A quantum dot-based light-emitting diode device, characterized in that: including a light emitting layer; The material of the light-emitting layer includes colloidal quantum dots and organic light-emitting materials; the mass ratio of the colloidal quantum dots to the organic light-emitting materials is 100:(0.1-20).

2. The quantum dot-based light-emitting diode device according to claim 1, characterized in that: The colloidal quantum dots are selected from one or more of zinc oxide quantum dots, gallium nitride quantum dots, calcium fluoride quantum dots, zinc sulfide quantum dots, cadmium sulfide quantum dots, cadmium selenide quantum dots, cadmium telluride quantum dots, indium phosphide quantum dots, lead sulfide quantum dots, lead selenide quantum dots, lead telluride quantum dots, mercury telluride quantum dots, silver sulfide quantum dots, silver selenide quantum dots, silver telluride quantum dots and indium arsenide quantum dots.

3. The quantum dot-based light-emitting diode device according to claim 1, characterized in that: The organic light-emitting material is selected from fluorescent materials and / or phosphorescent materials; the fluorescent material is selected from traditional fluorescent materials and / or thermally activated delayed fluorescent materials.

4. The quantum dot-based light-emitting diode device according to claim 1, characterized in that: The light emission peak of the organic light emitting material is located in the ultraviolet-visible-infrared region.

5. The quantum dot-based light-emitting diode device according to claim 1, characterized in that: It also includes one or more of an anode, a hole injection layer, a hole transport layer, an electron transport layer, an electron injection layer and a cathode.

6. The quantum dot-based light-emitting diode device according to claim 5, characterized in that: The material of the hole injection layer is selected from one or more of poly(3,4-ethylenedioxythiophene)-polystyrene sulfonic acid, nickel oxide and molybdenum oxide; The material of the hole transport layer is selected from one or more of poly[bis(4-phenyl)(4-butylphenyl)amine], poly(9-vinylcarbazole) and polytriphenylamine.

7. The quantum dot-based light-emitting diode device according to claim 5, characterized in that: The material of the electron transport layer is selected from one or more of 2,4,6-tris[3-(diphenylphosphinoyl)phenyl]-1,3,5-triazole, 3,3'-[5'-[3-(3-pyridyl)phenyl][1,1':3',1''-terphenyl]-3,3''-diyl]bipyridine and 2,2',2''-(1,3,5-phenyl)triazine-3,3',3''-triylbenzene; The material of the electron injection layer is selected from one or more of 8-hydroxyquinoline-lithium, lithium fluoride and (tris(8-hydroxyquinoline)aluminum).

8. A method for preparing a quantum dot-based light-emitting diode device according to any one of claims 1 to 7, characterized in that: The following steps are involved: S1, sequentially preparing a hole injection layer and a hole transport layer on the anode by spin coating; S2, spin coating a composite solution on the hole transport layer to obtain a light-emitting layer; the composite solution includes a colloidal quantum dot solution and an organic light-emitting material solution; S3. Prepare an electron transport layer, an electron injection layer and a cathode in sequence on the surface of the light-emitting layer by vacuum evaporation to obtain the quantum dot-based light-emitting diode device.

9. The method for preparing a quantum dot-based light-emitting diode device according to claim 8, characterized in that: In S2, the concentration of the colloidal quantum dot solution is 10 mg / mL-30 mg / mL; The concentration of the organic light-emitting material solution is 0.01 mg / mL-150 mg / mL.

10. The method for preparing a quantum dot-based light-emitting diode device according to claim 8, characterized in that: In S2, the volume ratio of the colloidal quantum dot solution to the organic light-emitting material solution is 100:(0.5-5).

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