Quantum dot light emitting diode, preparation method thereof and display device containing same
Patent Information
- Application Number
- CN202580005950.X
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2025-07-23
- Publication Date
- 2026-08-18
AI Technical Summary
[0014]应用上述技术方案，稳定化层可以减少反射性电极中的金属离子对电子传输层中的金属氧化物纳米晶的渗透，从而使得电子传输层的性质稳定化，提高QLED器件高温保存的稳定性。
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Figure CN122603597A_ABST
Abstract
Description
Technical Field
[0001] This disclosure relates to the field of quantum dot light-emitting diode technology, and more specifically, to a quantum dot light-emitting diode, a method for fabricating the same, and a display device containing the same. Background Technology
[0002] Quantum dot light-emitting diodes (QLEDs) based on semiconductor quantum dots have shown broad application prospects in the display and lighting fields due to their advantages such as better monochromaticity, color saturation, and lower manufacturing costs. Although the main performance indicators of QLED devices, such as luminous brightness, external quantum efficiency (EQE), and lifetime, have been greatly improved after rapid development in recent years, how to maintain high efficiency, long lifetime, and high stability while achieving high brightness remains a pressing problem in the QLED field and a key technological bottleneck restricting its application in display and lighting. Summary of the Invention
[0003] The purpose of this disclosure is to provide a quantum dot light-emitting diode, a method for fabricating the same, and a display device containing the same, thereby improving the stability of the device during high-temperature storage.
[0004] According to a first aspect of this application, a quantum dot light-emitting diode (LED) is provided, comprising a first electrode, a hole injection layer, a hole transport layer, a quantum dot light-emitting layer, an electron transport layer, a stabilization layer, and a second electrode sequentially disposed therefrom; the first electrode is a transmissive electrode, the second electrode is a reflective electrode, and the stabilization layer comprises Yb₂O. x x is 2 to 3, and the electron transport layer comprises metal oxide nanocrystals.
[0005] Furthermore, the thickness of the stabilization layer is 5–50 nm.
[0006] Furthermore, the metal oxide is zinc oxide nanocrystals, and the surface of the nanocrystals has carboxylate ligands.
[0007] According to a second aspect of this application, a method for preparing the aforementioned quantum dot light-emitting diode is provided. The method for preparing the stabilization layer includes: depositing a metal Yb layer on the electron transport layer, then depositing a second electrode on the metal Yb layer, and placing the obtained first quantum dot light-emitting diode intermediate in air for a certain period of time to allow the metal Yb layer to undergo an oxidation reaction.
[0008] Furthermore, the humidity of the air is 30-60%.
[0009] Furthermore, the specified time period is from 5 minutes to 1 hour.
[0010] Furthermore, the deposition rate of the deposited metal Yb layer is as follows:
[0011] Furthermore, the quantum dot light-emitting layer and the electron transport layer are prepared by solution method.
[0012] Furthermore, the quantum dot light-emitting layer does not require annealing during preparation; preferably, the method for preparing the electron transport layer includes placing the metal oxide nanocrystal solution on the quantum dot light-emitting layer, and then placing the second quantum dot light-emitting diode intermediate in the air for a certain period of time.
[0013] According to a third aspect of this application, a display device is provided, the display device comprising any of the quantum dot light-emitting diodes described above, or a quantum dot light-emitting diode prepared by any of the above-described preparation methods.
[0014] By applying the above technical solution, the stabilization layer can reduce the penetration of metal ions in the reflective electrode into the metal oxide nanocrystals in the electron transport layer, thereby stabilizing the properties of the electron transport layer and improving the stability of QLED devices during high-temperature storage. Attached Figure Description
[0015] The accompanying drawings, which form part of this application, are used to provide a further understanding of this disclosure. The illustrative embodiments of this disclosure and their descriptions are used to explain this disclosure and do not constitute an undue limitation of this disclosure. In the drawings:
[0016] Figure 1 This is a schematic diagram of the structure of a quantum dot light-emitting diode according to an embodiment of the present disclosure. Detailed Implementation
[0017] It should be noted that the following detailed descriptions are illustrative and intended to provide further explanation of this application. Unless otherwise specified, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this application pertains.
[0018] According to a first aspect of this application, a quantum dot light-emitting diode (LED) is provided. The LED includes a first electrode, a hole injection layer, a hole transport layer, a quantum dot light-emitting layer, an electron transport layer, a stabilization layer, and a second electrode, which are sequentially disposed therefrom. The first electrode is a transmissive electrode, the second electrode is a reflective electrode, and the stabilization layer includes Yb₂O. x The x-coefficient is 2-3, and the electron transport layer comprises metal oxide nanocrystals. This stabilization layer reduces the penetration of metal ions from the reflective electrode into the metal oxide nanocrystals in the electron transport layer, thereby stabilizing the properties of the electron transport layer and improving the stability of the QLED device during high-temperature storage. On the other hand, the stabilization layer contains Yb₂O₃. xThe oxidized state has good conductivity and a low work function, which does not affect the original performance of the device. Figure 1 This illustration shows a positive structure diagram of the quantum dot light-emitting diode device according to an embodiment of this application, as shown below. Figure 1 As shown, the positive structure quantum dot light-emitting diode device includes, from bottom to top, a first electrode (anode), a hole injection layer, a hole transport layer, a quantum dot light-emitting layer, an electron transport layer, a stabilization layer, and a second electrode (cathode).
[0019] In some embodiments, the thickness of the stabilization layer is 5–50 nm. This thickness range allows for shorter post-processing time for the Yb metal layer while achieving stabilization. The quantum dot light-emitting diode (LED) can have one or more quantum dot emitting layers. The quantum dot LED can also have one or more hole transport layers. The LED may further include any layers to achieve other desired functions. In some embodiments, the thickness of the hole injection layer (HIL) can range from tens to hundreds of nanometers, for example, 20 nm–300 nm, preferably 30 nm–150 nm; the thickness of the hole transport layer (HTL) can range from tens to hundreds of nanometers, for example, 10 nm–200 nm, preferably 15 nm–100 nm. The thickness of the quantum dot emitting layer can range from tens to hundreds of nanometers, for example, 10 nm–100 nm, preferably 15 nm–60 nm. The thickness of the second electrode can be several hundred nanometers, for example, 100 nm–200 nm.
[0020] In some embodiments, the metal oxide is not doped with other metal ions. In some embodiments, the metal oxide is zinc oxide nanocrystals with carboxylate ligands on its surface.
[0021] In some embodiments, the first electrode includes, but is not limited to, one or more of indium-doped tin oxide (ITO), fluorine-doped tin oxide (FTO), antimony-doped tin oxide (ATO), and aluminum-doped zinc oxide (AZO).
[0022] In some embodiments, the hole injection layer material includes, but is not limited to, one or more of poly(3,4-ethylenedioxythiophene)-polystyrene sulfonic acid (PEDOT:PSS), undoped transition metal oxides, doped transition metal oxides, metal sulfides, and doped metal sulfides.
[0023] In some embodiments, the material of the hole transport layer may be selected from organic materials with hole transport capabilities, including but not limited to poly(9,9-dioctylfluorene-CO-N-(4-butylphenyl)diphenylamine) (TFB), polyvinylcarbazole (PVK), poly(N,N'-bis(4-butylphenyl)-N,N'-bis(phenyl)benzidine) (poly-TPD), poly(9,9-dioctylfluorene-co-bis-N,N-phenyl-1,4-phenylenediamine) (PFB), 4,4',4”-tris(carbazole-9-yl)triphenylamine (TCTA), 4,4'-bis(9-carbazole)biphenyl (CBP), and N,N'-diphenyl-N,N' -Di(3-methylphenyl)-1,1'-biphenyl-4,4'-diamine (TPD), N,N'-diphenyl-N,N'-(1-naphthyl)-1,1'-biphenyl-4,4'-diamine (NPB), poly[9,9-dioctylfluorenyl-2,7-diyl]-alt-(9-(2-ethylhexyl)-carbazole-3,6-diyl)](PF8Cz), doped graphene, undoped graphene, C60, or any mixture thereof. The hole transport layer material may also be selected from inorganic materials with hole transport capabilities, including but not limited to doped or undoped NiO, WO3, MoO3, CuO, or any mixture thereof.
[0024] In some embodiments, the hole injection layer is made of PEDOT:PSS, and the hole transport layer is made of cross-linked or non-cross-linked TFB.
[0025] In some embodiments, the quantum dot material used in the quantum dot light-emitting layer includes, but is not limited to, one or more of group II-VI compounds, group III-V compounds, group II-V compounds, group III-VI compounds, group IV-VI compounds, group I-III-VI compounds, group II-IV-VI compounds, and group IV elements. The quantum dot material used in the quantum dot light-emitting layer also includes, but is not limited to, nanocrystals of II-VI semiconductors, such as CdS, CdSe, CdTe, ZnS, ZnSe, ZnTe, HgS, HgSe, HgTe, PbS, PbSe, PbTe, and other binary, ternary, and quaternary II-VI compounds; and nanocrystals of III-V semiconductors, such as GaP, GaAs, InP, InAs, and other binary, ternary, and quaternary III-V compounds. The quantum dot material used in the quantum dot light-emitting layer is not limited to, group II-V compounds, group III-VI compounds, group IV-VI compounds, group I-III-VI compounds, group II-IV-VI compounds, and group IV elements.
[0026] The quantum dot emissive layer can emit green light, with a maximum emission wavelength in the range of 500 nm or greater (e.g., 510 nm or greater) and 560 nm or less (e.g., 540 nm or less). The quantum dot emissive layer can emit red light, with a maximum emission wavelength in the range of 600 nm or greater (e.g., 610 nm or greater) and 650 nm or less (e.g., 640 nm or less). The quantum dot emissive layer can emit blue light, with a maximum emission wavelength in the range of 440 nm or greater (e.g., 450 nm or greater) and 480 nm or less (e.g., 465 nm or less).
[0027] Quantum dots can be synthesized by any method. For example, semiconductor nanocrystals with dimensions of a few nanometers can be synthesized using wet chemical processes. In wet chemical processes, crystal particles are grown by reacting precursor materials in an organic solvent, and the growth of the crystals can be controlled by coordinating organic solvents or ligand compounds on the surface of the semiconductor nanocrystals.
[0028] In some embodiments, the material of the electron transport layer includes metal oxide nanocrystals with an electron transport capability and a band gap larger than that of the luminescent material, including but not limited to one or more of ZnO, TiO2, SnO2, Ta2O3, ZrO2, NiO, TiLiO, ZnAlO, ZnMgO, ZnSnO, ZnLiO, and InSnO.
[0029] In some embodiments, the second electrode comprises a metallic material. The metallic material includes one or more of Al, Ag, Cu, Mo, Au, Ba, Ca, and Mg.
[0030] In some embodiments, the quantum dot light-emitting diode may further include a capping layer disposed above the electrodes. The capping layer can improve the light extraction efficiency of the device.
[0031] In some embodiments, the capping layer can be composed of a high refractive index (n) material, typically n greater than 1.65, preferably greater than 1.8. The thickness of the capping layer can range from tens of nanometers to thousands of nanometers. In some implementations, the capping layer can be formed from organic small molecule materials via thermal evaporation processes, such as NPB, Alq, CBP, etc.; the thickness of the capping layer can be, for example, 20 nm-400 nm. In some implementations, the capping layer can be made of inorganic materials, which can be formed via chemical vapor deposition (CVD) or physical vapor deposition (PVD) processes, such as Al2O3, SixNy, S ix N y O zThe thickness can be, for example, 20nm-400nm. In some implementations, the coating layer can be made of an organic-inorganic hybrid material, fabricated using a wet film-forming process, such as slot coating, inkjet printing, ultrasonic spraying, screen printing, etc.; the thickness can be, for example, 300nm-3000nm. The organic material can be a polymer resin, such as acrylic resin, epoxy resin, etc., or can be selected from polymethyl methacrylate, polycyclic olefins, etc. The inorganic material can be selected from metal compound particles, such as alumina, titanium dioxide, zirconium oxide, etc. Preferably, the particle size of the inorganic particles generally does not exceed 1000nm.
[0032] According to a second aspect of this application, a method for preparing the aforementioned quantum dot light-emitting diode is provided. The method for preparing the stabilization layer includes: depositing a metal Yb layer on an electron transport layer, then depositing a second electrode on the metal Yb layer, and placing the obtained intermediate quantum dot light-emitting diode in air for a certain period of time to allow the metal Yb layer to undergo an oxidation reaction.
[0033] The above-mentioned method for fabricating a quantum dot light-emitting diode may include: preparing a substrate having a first electrode; fabricating a hole injection layer on the first electrode; fabricating a hole transport layer on the hole injection layer; fabricating a quantum dot light-emitting layer on the hole transport layer; fabricating an electron transport layer on the quantum dot light-emitting layer; fabricating a metallic Yb layer on the electron transport layer; fabricating a second electrode on the metallic Yb layer; and placing the obtained first quantum dot light-emitting diode intermediate in air for a certain period of time to allow the metallic Yb layer to undergo an oxidation reaction. Ordinary air environment reduces the fabrication requirements and cost of the device.
[0034] In some embodiments, the atmospheric humidity is 30–60%. The aforementioned time period can be determined by considering the thickness of the stabilization layer, the effect of Yb oxidation, the impact on device performance, and the fabrication efficiency. In some embodiments, the time period is 5 minutes to 1 hour.
[0035] In some embodiments, the deposition rate of the vaporized Yb metal layer is: This results in a more uniform and dense metal film.
[0036] In some embodiments, the quantum dot light-emitting layer and electron transport layer are prepared by solution methods. Solution methods include spin coating, full-surface coating, inkjet printing, photolithography, etc.
[0037] In some embodiments, the quantum dot light-emitting layer is prepared without annealing; preferably, the method for preparing the electron transport layer includes depositing a metal oxide nanocrystal solution on the quantum dot light-emitting layer, and then placing a second quantum dot light-emitting diode intermediate in air for a certain period of time. This reduces the defect states of the electron transport layer material.
[0038] In some embodiments, the hole injection layer and the hole transport layer are also prepared by solution method. In some embodiments, the preparation of the hole injection layer and the hole transport layer includes an annealing process, preferably with an annealing temperature of 130-170°C and an annealing time of 15-45 min.
[0039] According to a third aspect of this application, a display device is provided, comprising a quantum dot light-emitting diode (LED) of any of the above-described types, or a quantum dot LED prepared by any of the above-described methods. The aforementioned display device exhibits improved operational stability.
[0040] The implementation methods are described in more detail below with reference to specific embodiments. However, these are exemplary examples of the present disclosure, and the present disclosure is not limited thereto.
[0041] Example 1
[0042] QLED positive device fabrication:
[0043] Cleaning of S1. ITO glass
[0044] Place the ITO glass slide with the number engraved on the back into a glass dish containing ethanol solution, clean the ITO side with a cotton swab, and then sonicate it with acetone, deionized water and ethanol for 10 minutes each in sequence. After that, blow it dry with a nitrogen gun. Finally, place the cleaned ITO glass slide in oxygen plasma for another 10 minutes.
[0045] S2. Preparation of Hole Injection Layer (PEDOT:PSS)
[0046] The cleaned ITO glass slide was spin-coated with Pedot:PSS in air at a speed of 3000 r / min for 45 seconds. After spin-coating, it was placed in air for annealing at a temperature of 150℃ for 30 minutes. After annealing, the slide was quickly transferred to a glove box in a nitrogen atmosphere.
[0047] S3. Hole Transport Layer (HTL) Preparation
[0048] The film obtained in step S2 was further spin-coated with a hole transport layer of TFB (10 mg / mL, chlorobenzene solution) at a speed of 2000 r / min for 45 seconds. After spin-coating, the film was annealed in a glove box at a temperature of 150°C for 30 minutes.
[0049] S4. Preparation of Quantum Dot Emitting Layers (QDs)
[0050] After annealing the wafer obtained in step S3, spin-coat the quantum dot solution (the quantum dots are CdZnSeS / ZnS core-shell quantum dots, PL peak wavelength = 470nm, the optical concentration of quantum dots at 350nm is 40, and the solvent is octane) at a spin-coating speed of 2000r / min and a spin-coating time of 45 seconds. After spin-coating, no annealing is required before spin-coating the next layer.
[0051] S5. Electron transport layer fabrication
[0052] The sheet obtained in step S4 was spin-coated with an undoped zinc oxide nanocrystal solution (30 mg / mL, solvent: ethanol) with carboxylate ligands on its surface at a speed of 2000 r / min for 45 seconds, and then the sheet was left to stand in air with a humidity of 60% for 30 min.
[0053] S6.Yb2O x Layer preparation
[0054] The wafer obtained in step S5 is placed in a vacuum chamber, and Yb is deposited by vapor deposition at a rate of [missing information]. The thickness of the metallic Yb layer is 5 nm, and then the device is placed in an atmosphere with a humidity of 30-60% and left to stand for 5 minutes.
[0055] S7. Electrode Preparation
[0056] The wafer obtained in step S6 is placed in a vacuum chamber, and the top electrode is deposited by vapor deposition at a rate of [missing information]. It is about 100nm thick.
[0057] S8. Electrode Preparation
[0058] The chip obtained in step S7 is packaged.
[0059] Example 2
[0060] The difference between Example 2 and Example 1 is that the thickness of the metal Yb layer in step S6 is 10 nm, and the device is placed in an atmosphere with a humidity of 30-60% and left to stand for 15 min.
[0061] Example 3
[0062] The difference between Example 3 and Example 1 is that the thickness of the metal Yb layer in step S6 is 20nm, and the device is placed in an atmosphere with a humidity of 30-60% for 30 minutes.
[0063] Example 4
[0064] The difference between Example 4 and Example 1 is that the thickness of the metal Yb layer in step S6 is 30nm, and the device is placed in an atmosphere with a humidity of 30-60% and left to stand for 30 minutes.
[0065] Example 5
[0066] The difference between Example 4 and Example 1 is that the thickness of the metal Yb layer in step S6 is 30nm, and the device is placed in an atmosphere with a humidity of 30-60% for 45 minutes.
[0067] Example 6
[0068] The difference between Example 4 and Example 1 is that the thickness of the metal Yb layer in step S6 is 50 nm, and the device is placed in an atmosphere with a humidity of 30-60% for 60 min.
[0069] Comparative Example 1
[0070] The difference from Example 1 is that step S6 is omitted.
[0071] Comparative Example 2
[0072] The difference from Example 1 is that a 10nm metal Ca layer is deposited in step S6.
[0073] Comparative Example 3
[0074] The difference from Example 1 is that a 10nm Mg metal layer is deposited in step S6.
[0075] T of electric field excited QLED 95 T in the parameters 95 The value represents the time required for the luminous intensity of the LED to decrease to 95% of its maximum value, expressed in hours. Table 1 below shows the device performance of various embodiments and comparative examples.
[0076] Example 1 9.7 8.3 150 Example 2 11.2 9.7 220 Example 3 10.9 9.6 270 Example 4 10.5 9.9 250 Example 5 10.8 10.2 310 Example 6 11.3 10.5 280 Comparative Example 1 9.2 6.5 100 Comparative Example 2 0.3 0.1 0 Comparative Example 3 8.7 5.5 60
[0077] As can be seen from the table above, the high-temperature (85°C) stability of the examples is significantly improved, and the T measured under the same conditions is also significantly improved. 95 Life expectancy has also increased.
[0078] The above description is merely a preferred embodiment of this disclosure and is not intended to limit this disclosure. Various modifications and variations can be made to this disclosure by those skilled in the art. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of this disclosure should be included within the scope of protection of this disclosure.
Claims
1. A quantum dot light-emitting diode, characterized in that, The quantum dot light-emitting diode includes a first electrode, a hole injection layer, a hole transport layer, a quantum dot light-emitting layer, an electron transport layer, a stabilization layer, and a second electrode arranged sequentially; the first electrode is a transmissive electrode, the second electrode is a reflective electrode, and the stabilization layer includes Yb₂O. x x is 2 to 3, and the electron transport layer comprises metal oxide nanocrystals.
2. The quantum dot light-emitting diode according to claim 1, characterized in that, The thickness of the stabilization layer is 5–50 nm.
3. The quantum dot light-emitting diode according to claim 1, characterized in that, The metal oxide is zinc oxide nanocrystals, and the surface of the zinc oxide nanocrystals has carboxylate ligands.
4. A method for fabricating a quantum dot light-emitting diode as described in any one of claims 1 to 3, characterized in that, The method for preparing the stabilization layer includes: depositing a metal Yb layer on the electron transport layer, then depositing the second electrode on the metal Yb layer, and placing the obtained first quantum dot light-emitting diode intermediate in the air for a certain period of time to allow the metal Yb layer to undergo an oxidation reaction.
5. The method for fabricating a quantum dot light-emitting diode according to claim 4, characterized in that, The humidity of the air is 30-60%.
6. The method for fabricating a quantum dot light-emitting diode according to claim 4, characterized in that, The specified time period is from 5 minutes to 1 hour.
7. The method for fabricating a quantum dot light-emitting diode according to claim 4, characterized in that, The deposition rate of the Yb metal layer is as follows:
8. The method for fabricating a quantum dot light-emitting diode according to claim 4, characterized in that, The quantum dot luminescent layer and the electron transport layer were prepared by a solution method.
9. The method for fabricating a quantum dot light-emitting diode according to claim 8, characterized in that, The quantum dot light-emitting layer is prepared without annealing; preferably, the method for preparing the electron transport layer includes placing the metal oxide nanocrystal solution on the quantum dot light-emitting layer, and then placing the second quantum dot light-emitting diode intermediate in the air for a certain period of time.
10. A display device, characterized in that, The display device includes a quantum dot light-emitting diode as described in any one of claims 1 to 3, or a quantum dot light-emitting diode prepared by any one of claims 4 to 9.