Full-color Micro-LED chip based on non-lead perovskite and preparation method thereof

Abstract

The invention provides a lead-free perovskite-based full-color Micro-LED chip and a preparation method thereof. The chip comprises a TFT substrate, an ultraviolet LED chip, a glass substrate, a lead-free perovskite color conversion layer and a packaging film from bottom to top, the non-lead-based perovskite color conversion layer comprises a red light perovskite color conversion layer, a green light perovskite color conversion layer and a blue light perovskite color conversion layer from left to right, and nano barrier layers are respectively arranged between the red light perovskite color conversion layer and the green light perovskite color conversion layer and between the green light perovskite color conversion layer and the blue light perovskite color conversion layer. The non-lead perovskite quantum dots are adopted as the color conversion layer and can be prepared through a normal-temperature solution method, the preparation cost is lower than that of a traditional quantum dot material, high thermal stability is achieved, and the luminous efficiency and the color purity can be improved. And the pollution of a lead-based perovskite material in the traditional Micro-LED is avoided by the non-lead perovskite material. According to the invention, the active light-emitting ultraviolet LED is used as an excitation source to excite the perovskite color conversion layer, so that the light-emitting efficiency can be improved.

Description

Technical Field

[0001] The present invention relates to a semiconductor light-emitting device technology, belonging to the technical field of realizing a method for preparing a Micro-LED chip based on non-lead perovskite. Background Art

[0002] In recent years, Micro-LED technology has garnered significant attention across various sectors. Compared to traditional LEDs, Micro-LEDs offer the advantage of being smaller. Composed of an array of multiple micron-sized LEDs, each micro-LED unit can be independently driven to emit light. Their luminous efficiency and brightness far exceed those of organic light-emitting diodes (OLEDs) and liquid crystal displays (LCDs), and they also boast a much longer lifespan.

[0003] With the development of display technology and people's constant pursuit of quality, in order to solve the problem of colorization of Micro-LED displays, research institutions and companies around the world are constantly proposing and expanding various methods to achieve Micro-LED full-color display. Currently, the mainstream technical solution for preparing Micro-LED arrays is to set up a color conversion layer and realize Micro LED array devices by integrating blue / violet light excitation light sources and color conversion layers. The method of using color conversion technology to prepare full-color arrays has the advantages of low cost, simple process and high integration. However, the current Micro-LED manufacturing process is complex, and the production cost of GaN materials is relatively high compared to traditional display technologies. GaN materials will generate significant heat in high-power and high-density applications.

[0004] Lead (Pb)-based halide perovskites (with the general formula APbX3, where the A position is a monovalent cation and the X position is a halide ion) offer advantages such as high photoelectric conversion efficiency, low cost, excellent thermal stability, and the ability to emit light across the entire visible light range. They hold broad application prospects in high-quality flat-panel displays and photodetection. However, currently studied metal halide perovskites are primarily based on lead-based halides. The toxicity of lead has severely hampered the development of these technologies, and the heavy metal Pb can cause irreversible damage to the environment and the human body. Therefore, there is an urgent need to develop non-lead metal halide perovskite luminescent materials with similar optoelectronic properties to lead-based halide perovskites and environmentally friendly properties to overcome this limitation. Summary of the Invention

[0005] Technical issues:

[0006] In response to the problems of high difficulty in Micro-LED chip processing, the pollution of lead-based perovskite materials, and the high production cost of GaN materials, the present invention adopts a full-color Micro-LED chip based on non-lead perovskite and its preparation method, using an ultraviolet LED with color conversion material as an excitation source to excite the red, green, and blue non-lead-based perovskite color conversion layers to achieve a full-color display Micro-LED chip.

[0007] Technical solution:

[0008] In order to achieve the above object, the present invention adopts the following technical solutions:

[0009] A full-color Micro-LED chip based on non-lead perovskite includes, from bottom to top, a TFT substrate, a UV LED chip, a glass substrate, a non-lead-based perovskite color conversion layer, and an encapsulation film. The non-lead-based perovskite color conversion layer includes, from left to right, a red perovskite color conversion layer, a green perovskite color conversion layer, and a blue perovskite color conversion layer. Nano-barrier layers are respectively arranged between the red perovskite color conversion layer and the green perovskite color conversion layer, and between the green perovskite color conversion layer and the blue perovskite color conversion layer.

[0010] Furthermore, the TFT substrate, as a switching element, is mainly used to control each pixel unit, and can accurately adjust the current through matrix driving technology to provide power for the ultraviolet LED chip.

[0011] Furthermore, the ultraviolet LED chip is characterized in that the ultraviolet LED light emission wavelength is set to 380-400 nm, which is beneficial to improving the RGB conversion efficiency.

[0012] Furthermore, the red / green / blue color conversion layer adopts II-VI or III-V group or perovskite quantum dot material, is deposited by sputtering, pad printing or spin coating, and then annealed, and is obtained by patterning preparation processes such as photolithography, printing, and screen printing; the conversion wavelength of the red light color conversion layer is between 650 and 720 nm, the half-peak width is ≤30 nm, and the film thickness is ≤100 nm; the conversion wavelength of the green light color conversion layer is between 500 and 550 nm, the half-peak width is ≤40 nm, and the film thickness is ≤100 nm; the conversion wavelength of the blue light color conversion layer is between 450 and 480 nm, the half-peak width is ≤40 nm, and the film thickness is ≤100 nm; the red / green / blue light color conversion layers are arranged horizontally, separated by nano-barrier layers, and will not dissolve or penetrate each other.

[0013] More specifically, the non-lead-based perovskite color conversion layer adopts a material with a chemical structure of AB2X3, A2BX4, A3B2X5, or A4BX6, wherein the A position is a monovalent metal cation (Cs + , Rb +) or organic functional groups (MA + , FA + ), B position is a divalent cation in the transition metal or Cu + , X position is a halogen ion (Cl - Br - , I - ), after weighing, dissolving, filtering, stirring with a magnetic stirrer, and heating. The red light non-lead perovskite color conversion layer has a luminescent material structure of AB2Br3 or A2BBr4; the green light non-lead perovskite color conversion layer has a luminescent material structure of A4BBr6. The blue light non-lead perovskite color conversion layer has a luminescent material structure of A3B2I5 or A2BCl4;

[0014] More specifically, the nano barrier layer is composed of a single layer of nano MgO or SnO2 particles with a particle size of 1-10 nm.

[0015] More specifically, the packaging film is made of any one of polyvinyl fluoride, silicone, polyurethane, and epoxy resin, and has good mechanical strength and certain heat resistance.

[0016] In a preferred embodiment, the full-color Micro-LED chip based on non-lead perovskite is driven by a TFT substrate, excited by an ultraviolet LED, and the perovskite color conversion layer photoluminescently produces red, green and blue light, ultimately achieving full-color display.

[0017] The present invention also provides a method for preparing a full-color Micro-LED chip based on non-lead perovskite, comprising the following steps:

[0018] S1: Clean the glass substrate in detergent, deionized water, acetone, and isopropyl alcohol for 10 to 20 minutes each, blow dry with nitrogen gas after cleaning; then, use ultraviolet ozone surface treatment for 15 to 30 minutes before use;

[0019] S2: preparing a red light perovskite color conversion layer, a green light perovskite color conversion layer, and a blue light perovskite color conversion layer on the glass substrate:

[0020] S21: Under a nitrogen environment, weigh the luminescent materials required for each color conversion layer and add them to dimethyl sulfoxide to obtain three perovskite precursor solutions with a concentration of 50 to 100 mg / ml;

[0021] S22: Under a nitrogen atmosphere, the three solutions are heated and stirred for 6 to 12 hours at a speed of 300 to 600 rpm and a temperature of 40 to 100° C.;

[0022] S23: Under a nitrogen environment, a nano-barrier layer is formed on a glass substrate by inkjet printing, electroplating, or nanoimprinting.

[0023] S24: Under nitrogen atmosphere, the three precursor solutions were filtered and spin-coated on a glass substrate from left to right.

[0024] S25: placing the glass substrate on a hot plate for annealing in a nitrogen environment for 10 to 50 minutes at a temperature of 60 to 120° C. to obtain a color conversion layer;

[0025] S3: curing the encapsulation film onto the color conversion layer;

[0026] S4: Align the color conversion layer unit with the UV LED light source to obtain a full-color display Micro-LED pixel unit.

[0027] Compared with the prior art, the present invention has the following beneficial effects:

[0028] 1. This invention uses non-lead perovskite quantum dots as the color conversion layer. These can be prepared via a room-temperature solution method at a lower cost than traditional quantum dot materials. They not only exhibit high thermal stability but also improve luminous efficiency and color purity. These non-lead perovskite materials avoid the polluting effects of lead-based perovskite materials found in traditional Micro-LEDs.

[0029] 2. Using an active ultraviolet LED as an excitation source to excite the perovskite color conversion layer is beneficial to improving the luminous efficiency and does not require the use of high-cost GaN materials and multi-layer blue light emitting chips.

[0030] 3. The present invention uses the photoluminescence of the perovskite color conversion layer, and does not have the electroluminescent HTL, ETL layer and other structures; the perovskite color conversion layer of the present invention does not add crown ether additives. BRIEF DESCRIPTION OF THE DRAWINGS

[0031] Figure 1 Schematic diagram of the device structure of a method for preparing a full-color Micro-LED chip based on non-lead perovskite.

[0032] Among them: TFT substrate 1, ultraviolet LED 2, glass substrate 3, red light perovskite color conversion layer 4, green light perovskite color conversion layer 5, blue light perovskite color conversion layer 6, nano barrier layer 7, and packaging film 8. DETAILED DESCRIPTION

[0033] The present invention relates to a method for preparing a full-color Micro-LED chip based on a non-lead perovskite structure. The following provides a clear and complete description of the technical method in this embodiment, combined with the accompanying drawings. The described embodiment is only a partial embodiment of the present invention, not a complete one.

[0034] Example 1

[0035] Figure 1 This is a schematic diagram of the Micro-LED chip device structure described in this embodiment, which consists of a TFT substrate 1, an ultraviolet LED chip 2, a glass substrate 3, a red light perovskite color conversion layer 4, a green light perovskite color conversion layer 5, a blue light perovskite color conversion layer 6, a nano-barrier layer 7, and an encapsulation film 8.

[0036] As a preferred embodiment, the TFT substrate 1 drives the thin film transistor to be turned on and off, thereby driving the ultraviolet LED to perform electroluminescence.

[0037] As a preferred embodiment, the emission wavelength of the ultraviolet LED chip 2 is set to 380 nm, which is beneficial to improving the RGB conversion efficiency.

[0038] As a preferred embodiment, the color conversion layers 4, 5, 6 are made of a material having a chemical structure of AB2X3, A2BX4, A3B2X5, A4BX6, where the A position is a monovalent metal cation (Cs + , Rb + ) or organic functional groups (MA + , FA + ), B position is a divalent cation in the transition metal or Cu + , X position is a halogen ion (Cl - Br - , I - ), after weighing, dissolving, filtering, stirring with a magnetic stirrer and heating treatment; the red light non-lead perovskite color conversion layer, the material structure of which is CsCu2Br3; the green light non-lead perovskite color conversion layer, the material structure of which is Cs4SnBr6; the blue light non-lead perovskite color conversion layer, the material structure of which is Cs3Cu2I5.

[0039] As a preferred embodiment, the packaging film 8 is made of any one of polyvinyl fluoride, silicone, polyurethane, and epoxy resin, and has good mechanical strength and certain heat resistance.

[0040] A method for preparing a full-color Micro-LED chip based on non-lead perovskite in an embodiment of the present invention comprises the following steps:

[0041] S1: The glass substrate was cleaned in detergent, deionized water, acetone, and isopropyl alcohol for 15 minutes each, and then dried with nitrogen. Then, the surface was treated with UV ozone for 30 minutes before use.

[0042] S2: preparing a red light perovskite color conversion layer, a green light perovskite color conversion layer, and a blue light perovskite color conversion layer on the glass substrate:

[0043] S21: Under a nitrogen atmosphere, a certain amount of cesium bromide, cuprous bromide, tin bromide, cesium iodide, and cuprous iodide were weighed using an electronic balance and added to dimethyl sulfoxide to obtain three perovskite precursor solutions with a solution concentration of 50 mg / ml;

[0044] S22: Under nitrogen atmosphere, the three solutions were heated and stirred for 10 hours at a speed of 600 rpm and a temperature of 70°C;

[0045] S23: Under nitrogen environment, the three precursor solutions are filtered using a 0.45 μm polytetrafluoroethylene filter;

[0046] S24: Under a nitrogen environment, a nano-barrier layer is formed on a glass substrate by inkjet printing, electroplating, or nanoimprinting.

[0047] S25: Under nitrogen environment, 200 μL of the filtered precursor solution was spin-coated on a glass substrate at a spin-coating speed of 3000 rpm for 60 seconds.

[0048] S26: placing the glass substrate on a hot plate for annealing under a nitrogen environment for 40 minutes at a temperature of 100° C. to obtain a color conversion layer;

[0049] S3: curing the polyvinyl fluoride packaging film onto the color conversion layer;

[0050] S4: Align the color conversion layer unit with the ultraviolet LED light source to obtain a full-color display Micro-LED pixel unit.

[0051] Example 2

[0052] In this embodiment, the color conversion layers 4, 5, and 6 are made of a material having a chemical structure of AB2X3, A2BX4, A3B2X5, or A4BX6, wherein the A position is a monovalent metal cation (Cs + , Rb + ) or organic functional groups (MA + , FA + ), B position is a divalent cation in the transition metal or Cu + , X position is a halogen ion (Cl - Br - , I -), after weighing, dissolving, filtering, stirring with a magnetic stirrer and heating treatment; the red light non-lead perovskite light-emitting layer, the structure of its light-emitting material is FA2CuBr4; the green light non-lead perovskite light-emitting layer, the structure of its light-emitting material is Cs4SnBr6; the blue light non-lead perovskite light-emitting layer, the structure of its light-emitting material is FA2CuCl4.

[0053] In this embodiment, a method for preparing a full-color Micro-LED chip based on non-lead perovskite is provided, and the method comprises the following steps:

[0054] S1: The glass substrate was cleaned in detergent, deionized water, acetone, and isopropyl alcohol for 15 minutes each, and then dried with nitrogen. Then, the surface was treated with UV ozone for 30 minutes before use.

[0055] S2: preparing a red light perovskite color conversion layer, a green light perovskite color conversion layer, and a blue light perovskite color conversion layer on the glass substrate:

[0056] S21: Under a nitrogen atmosphere, a certain amount of formamidine bromide, cuprous bromide, cesium bromide, tin bromide, copper chloride, and formamidine chloride were weighed using an electronic balance and added to dimethyl sulfoxide to obtain three perovskite precursor solutions with a solution concentration of 70 mg / ml;

[0057] S22: Under nitrogen atmosphere, the three solutions were heated and stirred for 12 hours at a speed of 500 rpm and a temperature of 60°C;

[0058] S23: Under nitrogen environment, the three precursor solutions are filtered using a 0.45 μm polytetrafluoroethylene filter;

[0059] S24: Under a nitrogen environment, a nano-barrier layer is formed on a glass substrate by inkjet printing, electroplating, or nanoimprinting.

[0060] S25: Under nitrogen environment, 100 μL of the filtered precursor solution was spin-coated on a glass substrate at a speed of 3000 rpm for 60 seconds.

[0061] S26: placing the glass substrate on a hot plate for annealing under a nitrogen environment for 10 minutes at a temperature of 120° C. to obtain a color conversion layer;

[0062] S3: curing the polyurethane encapsulation film onto the color conversion layer;

[0063] S4: Align the color conversion layer unit with the ultraviolet LED light source to obtain a full-color display Micro-LED pixel unit.

[0064] Comparative Example 1

[0065] In this comparative example, the preparation method of the color conversion layer in Example 1 is compared, and the method includes the following steps:

[0066] S1: Clean the glass substrate in detergent, deionized water, acetone, and isopropyl alcohol for 15 minutes each, then blow dry with nitrogen. Then, treat the surface with UV-ozone for 30 minutes before use.

[0067] S2: preparing a red light perovskite color conversion layer, a green light perovskite color conversion layer, and a blue light perovskite color conversion layer on the glass substrate:

[0068] S21: Under a nitrogen atmosphere, a certain amount of cesium bromide, cuprous bromide, tin bromide, cesium iodide, and cuprous iodide were weighed using an electronic balance and added to dimethyl sulfoxide to obtain three perovskite precursor solutions with a solution concentration of 50 mg / ml;

[0069] S22: Under nitrogen atmosphere, the three solutions were heated and stirred for 10 hours at a speed of 600 rpm and a temperature of 70°C;

[0070] S23: Under nitrogen environment, the three precursor solutions are filtered using a 0.45 μm polytetrafluoroethylene filter;

[0071] S24: Under a nitrogen environment, a nano-barrier layer is formed on a glass substrate by inkjet printing, electroplating, or nanoimprinting.

[0072] S25: Under nitrogen atmosphere, 200 μL of the filtered precursor solution was spin-coated on a glass substrate in sequence using a two-step spin coating method. The first step was at a speed of 500 rpm for 5 seconds, and the second step was at a speed of 3000 rpm for 60 seconds. At 45 seconds, 100 μL of toluene antisolvent was added dropwise on the precursor to promote rapid crystallization of the precursor.

[0073] S26: placing the glass substrate on a hot plate for annealing under a nitrogen environment for 40 minutes at a temperature of 100° C. to obtain a color conversion layer;

[0074] S3: curing the polyvinyl fluoride packaging film onto the color conversion layer;

[0075] S4: Align the color conversion layer unit with the ultraviolet LED light source to obtain a full-color display Micro-LED pixel unit.

[0076] The above describes the basic principles, main features, and advantages of the present invention. The present invention is not limited to the above embodiments. The above embodiments and descriptions are merely illustrative of the principles of the present invention. Various changes and modifications may be made to the present invention without departing from the spirit and scope of the present invention. Such changes and modifications are intended to fall within the scope of the invention as claimed.

Claims

1. A full-color Micro-LED chip based on non-lead perovskite, characterized in that: From bottom to top, it includes a TFT substrate, an ultraviolet LED chip, a glass substrate, a non-lead-based perovskite color conversion layer, and an encapsulation film. The non-lead-based perovskite color conversion layer includes a red light perovskite color conversion layer, a green light perovskite color conversion layer, and a blue light perovskite color conversion layer from left to right. Nano-barrier layers are respectively arranged between the red light perovskite color conversion layer and the green light perovskite color conversion layer, and between the green light perovskite color conversion layer and the blue light perovskite color conversion layer.

2. The full-color Micro-LED chip based on non-lead perovskite according to claim 1, characterized in that: The TFT substrate is used as a switching element to control each pixel unit in the ultraviolet LED chip, and can adjust the current through matrix driving technology to provide power for the ultraviolet LED chip.

3. The full-color Micro-LED chip based on non-lead perovskite according to claim 1, characterized in that: The ultraviolet LED in the ultraviolet LED chip has a light emission wavelength of 380 to 400 nm.

4. The full-color Micro-LED chip based on non-lead perovskite according to claim 1, characterized in that: The non-lead-based perovskite color conversion layer adopts II-VI or III-V group or perovskite quantum dot materials, which are deposited by sputtering, pad printing or spin coating and then annealed, and are obtained by patterning preparation processes such as photolithography, printing, and screen printing.

5. The full-color Micro-LED chip based on non-lead perovskite according to claim 1, characterized in that: The conversion wavelength of the red light perovskite color conversion layer is between 650 and 720 nm, the half-peak width is ≤30 nm, and the film thickness is ≤100 nm; the conversion wavelength of the green light perovskite color conversion layer is between 500 and 550 nm, the half-peak width is ≤40 nm, and the film thickness is ≤100 nm; the conversion wavelength of the blue light perovskite color conversion layer is between 450 and 480 nm, the half-peak width is ≤40 nm, and the film thickness is ≤100 nm.

6. The full-color Micro-LED chip based on non-lead perovskite according to claim 1, characterized in that: The non-lead-based perovskite color conversion layer adopts a material with a chemical structure of AB2X3, A2BX4, A3B2X5 or A4BX6, wherein the A position is a monovalent metal cation or an organic functional group, and the B position is a divalent cation in a transition metal or Cu + , X position is a halogen ion, which is obtained after weighing, dissolving, filtering, stirring with a magnetic stirrer and heating treatment.

7. The full-color Micro-LED chip based on non-lead perovskite according to claim 6, characterized in that: The red light perovskite color conversion layer has a luminescent material structure of AB2Br3 or A2BBr4; the green light perovskite color conversion layer has a luminescent material structure of A4BBr6; and the blue light perovskite color conversion layer has a luminescent material structure of A3B2I5 or A2BCl4.

8. The full-color Micro-LED chip based on non-lead perovskite according to claim 1, characterized in that: The nano barrier layer is composed of a single layer of nano MgO or SnO2 particles, and the particle size is 1-10nm.

9. The full-color Micro-LED chip based on non-lead perovskite according to claim 1, characterized in that: The material used for the packaging film is any one of polyvinyl fluoride, silicone, polyurethane and epoxy resin.

10. The method for preparing a full-color Micro-LED chip according to any one of claims 1 to 9, characterized in that: The steps include: S1: Clean the glass substrate in detergent, deionized water, acetone, and isopropyl alcohol for 10 to 20 minutes each, blow dry with nitrogen gas after cleaning; then, use ultraviolet ozone surface treatment for 15 to 30 minutes before use; S2: preparing a red light perovskite color conversion layer, a green light perovskite color conversion layer, and a blue light perovskite color conversion layer on the glass substrate, the steps comprising: S21: Under a nitrogen environment, weigh the luminescent materials required for each color conversion layer and add them to dimethyl sulfoxide to obtain three perovskite precursor solutions with a concentration of 50 to 100 mg / ml; S22: Under a nitrogen atmosphere, the three solutions are heated and stirred for 6 to 12 hours at a speed of 300 to 600 rpm and a temperature of 40 to 100° C.; S23: Under a nitrogen environment, a nano-barrier layer is formed on a glass substrate by inkjet printing, electroplating, or nanoimprinting. S24: Under nitrogen atmosphere, the three precursor solutions were filtered and spin-coated on a glass substrate from left to right. S25: placing the glass substrate on a hot plate for annealing in a nitrogen environment for 10 to 50 minutes at a temperature of 60 to 120° C. to obtain a color conversion layer; S3: curing the encapsulation film onto the color conversion layer; S4: Align the color conversion layer unit with the UV LED light source to obtain a full-color display Micro-LED pixel unit.

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