Perovskite quantum dot Micro-LED based on double-ligand strategy and preparation method thereof
By adding double ligand materials to the perovskite quantum dot layer, the material properties of the perovskite quantum dots are optimized, the problem of poor stability and sensitivity of perovskite quantum dots in high temperature environments is solved, and preparation and preparation in air are achieved. Perovskite quantum dot Micro-LED, which is stable at high temperatures, improves the color expression and reliability of displays.
Patent Information
- Application Number
- CN202411406461.9
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2024-10-10
- Publication Date
- 2025-01-14
AI Technical Summary
The existing perovskite quantum dots have poor stability in high temperature environments and are sensitive to oxygen and moisture. The preparation process needs to be carried out in an inert atmosphere, which increases the difficulty and cost of manufacturing, and the color conversion efficiency and optical performance have not yet reached the ideal level.
采用双配体策略，通过在钙钛矿量子点层中添加PEABr和含氟取代苯基酮材料，优化钙钛矿量子点的材料性能，实现在空气中制备并在高温下稳定。
It improves the environmental stability and luminous efficiency of perovskite quantum dots, reduces the difficulty and cost of preparation, and enhances the color expression and reliability of Micro-LED displays.
Smart Images
Figure CN119317289A_ABST
Abstract
Description
Technical Field
[0001] This technology belongs to the field of semiconductor technology, covering all aspects related to semiconductor materials, devices, manufacturing processes and applications, and specifically involves a perovskite quantum dot Micro-LED based on a dual ligand strategy and its preparation method. Background Art
[0002] At present, the application of color conversion technology based on perovskite quantum dots in Micro-LED displays has made initial progress. Perovskite quantum dots have become a research hotspot for emerging display materials due to their unique optoelectronic properties and adjustable emission wavelength. Perovskite quantum dots not only have high photoelectric conversion efficiency, but can also be prepared by simple chemical methods at a low cost. In color conversion technology, perovskite quantum dots can be excited by external light sources to achieve efficient color conversion, thereby improving the color expression and energy efficiency of the display.
[0003] However, the existing technical solutions still have some shortcomings. First, the stability of perovskite quantum dots in high temperature environments is poor, which affects the reliability of their practical applications. Secondly, perovskite quantum dots are usually very sensitive to oxygen and moisture and are easily degraded in the air. In order to ensure the quality and stability of perovskite quantum dots, the preparation process is generally carried out in an inert atmosphere (such as nitrogen or argon), which increases the difficulty and cost of manufacturing. In addition, the existing color conversion efficiency and optical performance have not yet reached the ideal level, which restricts the further improvement of the display effect.
[0004] Therefore, it is urgent to develop a Micro-LED based on perovskite quantum dots and its preparation method to overcome the shortcomings of the existing technology. By improving the material properties of perovskite quantum dots and optimizing the integration process, the color expression and reliability of Micro-LED displays can be improved, the manufacturing cost can be reduced, and the further development of display technology can be promoted. Summary of the invention
[0005] In order to overcome the limitations of the existing technology and improve the luminous efficiency and long-term stability of the device, the present invention proposes a perovskite quantum dot Micro-LED based on a dual ligand strategy and a preparation method thereof. By optimizing the material design, the dual ligand strategy can be used to prepare perovskite quantum dots in the air, and the perovskite quantum dots are more stable in a high temperature environment.
[0006] In order to achieve the above technical objectives and the above technical effects, the present invention is implemented through the following technical solutions:
[0007] A perovskite quantum dot Micro-LED based on a dual-ligand strategy consists of four parts: a distributed Bragg reflector, a quantum dot color conversion unit, a GaN blue LED, and a CMOS integrated circuit substrate. The quantum dot color conversion unit includes, from bottom to top, a glass substrate, a metal electrode, an electrode modification layer, an electron transport layer, a perovskite quantum dot layer, a hole transport layer, a hole injection layer, a transparent electrode, and a packaging film.
[0008] Specifically, it includes a perovskite quantum dot layer, the light-emitting material of the perovskite quantum dot layer is CsPbX3, and a dual ligand material is added: PEABr and fluorine-containing substituted phenyl ketone.
[0009] More specifically, the mass ratio of CsPbX3, PEABr and fluorine-containing substituted phenyl ketone is 1:0.17-0.25:0.11-0.20.
[0010] More specifically, the perovskite quantum dot layer is ground in an agate mortar with 126-136 mg CsPbX3, 23-32 mg PEABr and 16-26 mg fluorinated substituted phenyl ketone to ensure uniform mixing. The evenly ground mixture is transferred to a corundum crucible and calcined at 600 ° C in air for 20 minutes. If iodine-containing perovskite quantum dots (PQDs) are prepared, the crucible needs to be sealed to prevent the volatilization and oxidation of iodide. The calcined powder is washed with deionized water and anhydrous ethanol, and the washed suspension is centrifuged at 8000 rpm / min for 5 minutes to collect the precipitate. The collected precipitate is dried at 50 ° C for 4 hours to obtain.
[0011] More specifically, the distributed Bragg reflector of the Micro-LED based on perovskite quantum dots is placed on top of the quantum dot color conversion unit.
[0012] More specifically, the quantum dot color conversion unit is vertically placed on the GaN blue light LED, and the glass substrate is aligned with the CMOS integrated circuit substrate.
[0013] More specifically, the metal target is evaporated onto the glass substrate to form a dense metal electrode.
[0014] More specifically, the electron modification layer of the quantum dot color conversion unit adopts a self-assembled monolayer (SAMs): such as octafluorophenylene sulfide (PFOTS) or trifluorophenylene sulfide (PFO-S) evaporated under the electron transport layer, wherein the electron transport layer adopts fluorine-doped metal oxide: such as fluorine-doped indium oxide (FTO).
[0015] Specifically, the hole transport layer of the quantum dot color conversion unit is made of a polymer material poly(3,4-ethylenedioxythiophene) / polystyrene sulfonate (PEDOT), which is spin-coated on the perovskite quantum dot layer. The hole injection layer is made of a metal oxide: such as tungsten oxide (WO3) or molybdenum oxide (MoO3) is spin-coated on the hole transport layer.
[0016] More specifically, the transparent electrode of the quantum dot color conversion unit is spray-printed on the hole injection layer by Ag, Au or Pt nanowire solution.
[0017] More specifically, the packaging film of the quantum dot color conversion unit is made of epoxy resin, silicone or polyurethane and is placed on the transparent electrode.
[0018] The above-mentioned perovskite quantum dot Micro-LED based on the dual ligand strategy adds dual ligand materials to the perovskite quantum dot layer to obtain an optimized light-emitting layer.
[0019] Beneficial effects:
[0020] 1. The perovskite quantum dot Micro-LED based on the dual ligand strategy of the present invention adds dual ligand material PEABr and fluorine-substituted phenyl ketone to the perovskite quantum dot layer to form an optimized perovskite quantum dot light-emitting layer, wherein the PEABr molecule has a large organic part, which can form a protective film on the surface of the perovskite quantum dots, effectively passivate surface defects, and can also enhance the environmental stability of the material and inhibit ion migration.
[0021] 2. The perovskite quantum dot Micro-LED based on the dual ligand strategy of the present invention adds dual ligand material PEABr and fluorinated substituted phenyl ketone to the perovskite quantum dot layer to form an optimized perovskite quantum dot light-emitting layer, wherein the F atom in the fluorinated substituted phenyl ketone material forms a hydrogen bond with the organic ammonium ion, and the hydrogen bond causes steric hindrance, which limits the excess PEABr. + The diffusion of fluorinated substituted phenyl ketone materials further improves the luminescence efficiency. In addition, the O atom of the carbonyl functional group in the fluorinated substituted phenyl ketone material is used to combine with the unpaired Pb 2+ coordination, thereby passivating the non-radiative recombination centers.
[0022] 3. The present invention does not require inert gas protection when preparing perovskite quantum dots, and the preparation can be completed in an air environment. In addition, the material remains stable at high temperatures, which reduces the difficulty of preparation and improves device efficiency. BRIEF DESCRIPTION OF THE DRAWINGS
[0023] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings required for use in the embodiments or the description of the prior art will be briefly introduced below. Obviously, for ordinary technicians in this field, other drawings can be obtained based on these drawings without paying any creative work.
[0024] Figure 1 A schematic diagram of the device structure of a perovskite quantum dot Micro-LED based on a dual-ligand strategy;
[0025] Figure 2 A schematic diagram of the structure of a color conversion unit of a perovskite quantum dot Micro-LED based on a dual-ligand strategy;
[0026] Figure 3 A schematic diagram of the perovskite quantum dot layer process of a perovskite quantum dot Micro-LED based on a dual-ligand strategy;
[0027] Figure 4 is the chemical structure formula of the perovskite dual-ligand material;
[0028] Figure 5 JVL curves of the perovskite light-emitting diodes prepared in Examples 1 and 2 and the comparative example;
[0029] Figure 6 J-EQE curves of the perovskite light-emitting diodes prepared in Examples 1 and 2 and the comparative example. DETAILED DESCRIPTION
[0030] Next, the technical solution will be described in detail and completely in conjunction with the accompanying drawings in the embodiments of the present invention. It should be clear that the embodiments only represent some examples of the present invention, not all examples. According to the embodiments of the present invention, any other embodiments that can be derived before the technical personnel in this field perform creative work are within the protection scope of the present invention.
[0031] Example 1
[0032] In this embodiment 1, the device structure is: a distributed Bragg reflector 1, a quantum dot color conversion unit 2, a GaN blue light LED array 3 and a CMOS integrated circuit substrate 4, such as Figure 1 shown.
[0033] The quantum dot color conversion unit 2 includes, from bottom to top, a glass substrate 5, a metal electrode 6, an electrode modification layer 7, an electron transport layer 8, a perovskite quantum dot layer 9, a hole transport layer 10, a hole injection layer 11, a transparent electrode 12, and a packaging film 13; the direction indicated by the arrow in the figure is the actual light emitting direction of the pixel, such as Figure 2 shown.
[0034] The perovskite quantum dot layer 9 is made of CsPbBr3, PEABr, and 2-bromo-4'-fluoroacetophenone. The process flow is as follows Figure 3 As shown. Among them, the molecular structure of PEABr and 2-bromo-4'-fluoroacetophenone is as follows Figure 4 The perovskite quantum dot 9 emits green light with an emission wavelength between 500 and 530 nm and a half-peak width of ≤18 nm; the GaN blue light LED array 3 emits a wavelength between 450 and 470 nm and a half-peak width of ≤20 nm.
[0035] The specific preparation process is as follows:
[0036] a. Distributed Bragg reflector: Use a spectrometer to test the actual reflection wavelength and reflectivity of the distributed Bragg reflector. By comparing the test results with the design requirements, evaluate whether its performance meets expectations to ensure that the best reflection effect is achieved within the target wavelength range.
[0037] b. Configure quantum dot color conversion unit:
[0038] 1. Use a suitable glass substrate for cleaning and alignment with the CMOS integrated circuit substrate;
[0039] 2. Evaporate the metal target onto the glass substrate to form a dense metal electrode;
[0040] 3. The electron modification layer is deposited under the electron transport layer using octafluorophenylene sulfide (PFOTS), and the electron transport layer is made of fluorine-doped metal oxide fluorine-doped indium oxide (FTO);
[0041] 4. The perovskite quantum dot layer is ground with 126 mg CsPbBr3, 23 mg PEABr and 20 mg 2-bromo-4'-fluoroacetophenone to ensure uniform mixing. The uniformly ground mixture is transferred to a corundum crucible and calcined at 600 ° C in air for 20 min. The calcined powder is washed with deionized water and anhydrous ethanol, and the washed suspension is centrifuged at 8000 rpm / min for 5 min to collect the precipitate. The collected precipitate is dried at 50 ° C for 4 h to obtain;
[0042] 5. The hole transport layer uses polymer material poly (3,4-ethylenedioxythiophene) / polystyrene sulfonate (PEDOT) and is spin-coated on the perovskite quantum dot layer. The hole injection layer uses metal oxide tungsten oxide (WO3) and is spin-coated on the hole transport layer;
[0043] 6. The transparent electrode is spray-printed on the hole injection layer by Au nanowire solution, and the packaging film is made of epoxy resin placed on the transparent electrode.
[0044] c.GaN blue LED array, a blue light emitting diode (LED) array made of gallium nitride (GaN) material, consists of multiple GaN blue LED chips, which are the actual light-emitting units. Each chip contains a GaN material layer that can emit blue light.
[0045] d.CMOS integrated circuit substrate, using silicon (Si) as the main material. Silicon substrate has good semiconductor properties.
[0046] By etching a large number of transistors on the wafer using photolithography technology, the GaN blue LED array is driven to emit electroluminescence, thereby stimulating the photoluminescence of the quantum dot color conversion layer. The electrical properties (current, voltage, brightness, efficiency, etc. of the device) are then characterized.
[0047] Example 2
[0048] In this embodiment 2, the device structure is: a distributed Bragg reflector 1, a quantum dot color conversion unit 2, a GaN blue light LED array 3 and a CMOS integrated circuit substrate 4, such as Figure 1 shown.
[0049] The quantum dot color conversion unit 2 includes, from bottom to top, a glass substrate 5, a metal electrode 6, an electrode modification layer 7, an electron transport layer 8, a perovskite quantum dot layer 9, a hole transport layer 10, a hole injection layer 11, a transparent electrode 12, and a packaging film 13; the direction indicated by the arrow in the figure is the actual light emitting direction of the pixel, such as Figure 2 shown.
[0050] The perovskite quantum dot layer 9 is made of CsPbI3, PEABr, and 2',4',5'-trifluoroacetophenone. The process flow is as follows Figure 3 As shown. Among them, the molecular structure of PEABr and 2',4',5'-trifluoroacetophenone is as follows Figure 4 The perovskite quantum dot 9 emits red light with an emission wavelength between 600 and 620 nm and a half-peak width of ≤30 nm; the GaN blue light LED array 3 emits a wavelength between 450 and 470 nm and a half-peak width of ≤20 nm.
[0051] The specific preparation process is as follows:
[0052] e. Distributed Bragg reflector: Use a spectrometer to test the actual reflection wavelength and reflectivity of the distributed Bragg reflector. By comparing the test results with the design requirements, evaluate whether its performance meets expectations to ensure that the best reflection effect is achieved within the target wavelength range.
[0053] f. Configure quantum dot color conversion unit:
[0054] 1. Use a suitable glass substrate for cleaning and alignment with the CMOS integrated circuit substrate;
[0055] 2. Evaporate the metal target onto the glass substrate to form a dense metal electrode;
[0056] 3. The electron modification layer is deposited under the electron transport layer using octafluorophenylene sulfide (PFOTS), and the electron transport layer is made of fluorine-doped metal oxide fluorine-doped indium oxide (FTO);
[0057] 4. The perovskite quantum dot layer is ground with 130 mg CsPbI3, 26 mg PEABr and 16 mg 2', 4', 5'-trifluoroacetophenone to ensure uniform mixing. The uniformly ground mixture is transferred to a corundum crucible, the crucible is sealed and calcined at 600 ° C for 20 min. The calcined powder is washed with deionized water and anhydrous ethanol, the washed suspension is centrifuged at 8000 rpm / min for 5 min, and the precipitate is collected. The collected precipitate is dried at 50 ° C for 4 h to obtain;
[0058] 5. The hole transport layer uses polymer material poly (3,4-ethylenedioxythiophene) / polystyrene sulfonate (PEDOT) and is spin-coated on the perovskite quantum dot layer. The hole injection layer uses metal oxide tungsten oxide (WO3) and is spin-coated on the hole transport layer;
[0059] 6. The transparent electrode is spray-printed on the hole injection layer by Au nanowire solution, and the packaging film is made of epoxy resin placed on the transparent electrode.
[0060] g.GaN blue LED array, a blue light emitting diode (LED) array made of gallium nitride (GaN) material, consists of multiple GaN blue LED chips, which are the actual light-emitting units. Each chip contains a GaN material layer that can emit blue light.
[0061] h.CMOS integrated circuit substrate, using silicon (Si) as the main material. Silicon substrate has good semiconductor properties. A large number of transistors are etched on the wafer using photolithography technology, which drives the GaN blue LED array to emit electroluminescence, thereby stimulating the photoluminescence of the quantum dot color conversion layer. The electrical properties (current, voltage, brightness, efficiency, etc. of the device) are then characterized.
[0062] Comparative Example
[0063] In this comparative example, only the configuration of the perovskite quantum dot layer in step b-4 is different from that in the embodiment, in which the dual ligand strategy is not adopted, and 23 mg of PEABr is directly added to the CsPbX3 solution. The remaining steps are the same as those in Example 1.
[0064] Performance Testing:
[0065] Devices were made from Examples 1, 2 and the comparative example, and electrical properties such as current density, voltage, brightness, and EQE were tested. The JVL curves obtained are shown in FIG. Figure 5 As shown, the J-EQE curve is as follows Figure 6 shown.
[0066] Depend on Figure 5 It can be seen that the current density and brightness of the device with the dual ligand strategy are increased. This is because the O atom of the carbonyl functional group in the fluorinated substituted phenyl ketone material binds to the unpaired Pb 2+ Coordination, thereby passivating non-radiative recombination centers and promoting carrier injection and transport.
[0067] Depend on Figure 6 It can be seen that the EQE of the devices with the dual ligand strategy has an upward trend. This is because the F atom forms a hydrogen bond with the organic ammonium ion, which causes steric hindrance and limits the excess PEA + The diffusion of can effectively passivate defects, inhibit non-radiative recombination, and improve device performance.
[0068] In the description of this specification, the description with reference to the terms "Example 1", "Example 2", "Comparative Example", etc. means that the specific features, structures, materials or characteristics described in conjunction with the embodiment or example are included in at least one embodiment or example of the present invention. In this specification, the schematic representation of the above terms does not necessarily refer to the same embodiment or example. Moreover, the specific features, structures, materials or characteristics described can be combined in any one or more embodiments or examples in a suitable manner.
[0069] The above shows and describes the basic principles, main features and advantages of the present invention. It should be understood by those skilled in the art that the present invention is not limited by the above embodiments, and the above embodiments and descriptions are only for explaining the principles of the present invention. Without departing from the spirit and scope of the present invention, the present invention may have various changes and improvements, and these changes and improvements all fall within the scope of the present invention to be protected.
Claims
1. A perovskite quantum dot Micro-LED based on a dual ligand strategy, comprising from top to bottom a distributed Bragg reflector, a quantum dot color conversion unit, a GaN blue light LED array, and a CMOS integrated circuit substrate, wherein the quantum dot color conversion unit comprises from bottom to top: A glass substrate, a metal electrode, an electrode modification layer, an electron transport layer, a perovskite quantum dot layer, a hole transport layer, a hole injection layer, a transparent electrode, and an encapsulation film, wherein the light-emitting material of the perovskite quantum dot layer includes CsPbX3 and a dual ligand material, wherein X is a halogen element.
2. A perovskite quantum dot Micro-LED based on a dual ligand strategy according to claim 1, characterized in that: The dual ligand material is PEABr and fluorine-containing substituted phenyl ketone.
3. The perovskite quantum dot Micro-LED based on a dual ligand strategy according to claim 1, characterized in that: The halogen element is Br, I or Cl.
4. The perovskite quantum dot Micro-LED based on a dual ligand strategy according to claim 2, characterized in that: The mass ratio of CsPbX3, PEABr and fluorinated substituted phenyl ketone is 1:0.17~0.25:0.11~0.
20.
5. A method for preparing a perovskite quantum dot Micro-LED based on a dual ligand strategy according to any one of claims 1 to 4, characterized in that: The steps include: In a mortar, CsPbX3, PEABr and fluorinated substituted phenyl ketone are ground and mixed evenly; the evenly ground mixture is transferred to a crucible and calcined in air; the calcined powder is washed with deionized water and anhydrous ethanol, the washed suspension is centrifuged, and the precipitate is collected; the collected precipitate is dried to obtain the final perovskite quantum dot Micro-LED.
6. The preparation method according to claim 5, characterized in that: The quantum dot color conversion unit forms a dense metal electrode layer by vapor-depositing a metal target material on a glass substrate; this process deposits metal vapor on the surface of the glass substrate in a vacuum environment.
7. The preparation method according to claim 5, characterized in that: The electron modification layer of the quantum dot color conversion unit is deposited under the electron transport layer by self-assembled monomolecular layer, wherein the electron transport layer is made of fluorine-doped metal oxide.
8. The preparation method according to claim 5, characterized in that: The hole transport layer of the quantum dot color conversion unit adopts polymer material poly(3,4-ethylenedioxythiophene) / polystyrene sulfonate, which is spin-coated on the perovskite quantum dot layer; the hole injection layer adopts metal oxide which is spin-coated on the hole transport layer.
9. The preparation method according to claim 5, characterized in that: The transparent electrode of the quantum dot color conversion unit is spray-printed on the hole injection layer by Ag, Au or Pt nanowire solution.
10. The preparation method according to claim 5, characterized in that: The packaging film of the quantum dot color conversion unit is made of epoxy resin, silica gel or polyurethane and is placed on the transparent electrode.