Micro-LED color conversion layer processing method based on perovskite quantum dot film

Abstract

The invention discloses a micro-LED color conversion layer processing method based on a perovskite quantum dot thin film, which comprises the following steps of: preparing a thin film on a quartz glass substrate by adopting a perovskite quantum dot material in a spin coater; processing the perovskite quantum dot film by using a laser processing method to form an array; a single-color Micro-LED display chip is combined with an array, so that color conversion is completed. According to the method for processing the perovskite quantum dot thin film through laser, array display is achieved, operation is easy and convenient, cost is low, a template is not needed, preparation efficiency is high, pixels of different sizes and intervals can be prepared according to requirements to serve as color conversion layers, color conversion is achieved in combination with a Micro-LED chip, and application of perovskite quantum dots in the aspect of display is further improved.

Description

Technical Field

[0001] The invention relates to a method for processing a Micro-LED color conversion layer based on a perovskite quantum dot film, and belongs to the technical field of perovskite. Background Art

[0002] With the continuous development of electronic information technology in human society, people have higher and higher requirements for the resolution of display devices, especially the emergence of VR / AR devices, making display technology one of the most popular research fields. Micro-LED display technology is one of the most important developments in the LED field after blue light GaN materials and white light LED lighting. As a hot research direction at present, Micro-LED, compared with TFT-LCD, OLED, and QLED technology, is a display technology that uses a mass transfer method to make a driving circuit through a CMOS integrated circuit process after miniaturizing, thinning, and matrixing the traditional light-emitting structure, thereby realizing fixed-point control and individual drive of each pixel in the backlight source. Its size is usually less than 50μm, and it has higher PPI, contrast, brightness, shorter response time, and longer working life. In addition to the conventional optical advantages, it has unique competitiveness such as micron-level spacing and addressable drive luminescence. In addition, the research on Micro-LED is still in its infancy, and there is huge room for improvement in performance. It is undoubtedly the next generation of revolutionary display technology. Perovskite materials have also been regarded as very promising semiconductor materials in recent years because of their unique performance and excellent optical properties. Since the Kovalenko research group reported the pure inorganic halogen perovskite CsPbX3 (X = Cl, Br, I), perovskite quantum dot materials have been widely studied in display devices, imaging, solar cells, lasers, and detectors. In particular, the controllable emission wavelength and high fluorescence efficiency make it likely to become an important component of the new generation of Micro-LED display devices.

[0003] Nowadays, as the pixel size is further reduced, the traditional mass transfer method is increasingly difficult to meet the requirements of small-size and small-pitch pixels, so many research groups are currently studying quantum dot color conversion Micro-LED technology. This method does not require the step of mass transfer, and can directly prepare green and red arrays on blue light Micro-LED chips, or directly prepare RGB three-color arrays on ultraviolet Micro-LED chips to achieve full-color Micro-LED display. At present, the color conversion layer is mainly prepared by combining quantum dot materials with inkjet printing, photolithography and nanoimprinting. For now, each method still has some defects that need to be improved. Inkjet printing technology is a non-contact printing method that can perform patterned printing without a mask, but it has high requirements for ink and is prone to coffee ring effect and nozzle clogging problems. Photolithography is a processing method based on photolithography technology with higher processing accuracy, but other solvents added during the processing may damage the material itself. Nanoimprinting technology, as a new type of micro-nano processing technology, can achieve ultra-high resolution transfer printing, which can currently reach 2nm, but there are problems such as contact contamination and alignment difficulties during the production process. Therefore, further research is needed on the scheme of preparing color conversion layers. Summary of the invention

[0004] The purpose of the present invention is to provide a method for processing a Micro-LED color conversion layer based on a perovskite quantum dot film, using an existing CsPbX3 (X = Cl, Br, I) perovskite quantum dot film, and using a photoquenching method to form a high-resolution array of the film for Micro-LED display. The method completes the photoquenching process by laser processing the quantum dot film, and finally forms an array on the film, so that it can be applied to Micro-LED display of color conversion technology.

[0005] A method for processing a Micro-LED color conversion layer based on a perovskite quantum dot film comprises the following steps:

[0006] Step 1: In a coating machine, a thin film is prepared on a quartz glass substrate using a perovskite quantum dot solution;

[0007] Step 2: Processing the perovskite quantum dot film using a laser processing method to form an array;

[0008] Step 3: Combine a monochrome Micro-LED display chip with the array obtained in step 2 to complete the color conversion.

[0009] Preferably, in step 1, the perovskite quantum dot solution is spin-coated on a clean silica substrate, and after drying, a perovskite quantum dot film is obtained, and the film thickness is 25nm±2nm, wherein the spin coating rate is 2000r / min, the time is 45s, and the film is left to dry for more than 24 hours, and the temperature is generally room temperature.

[0010] Specifically, the perovskite quantum dots are CsPbBr3, the solvent of the perovskite quantum dot solution is toluene, and the concentration of the perovskite quantum dots is 0.135 mmol / ml.

[0011] Preferably, in step 2, the perovskite quantum dot film is processed by a laser processing method to form an array, and the specific process is as follows: a silicon dioxide substrate coated with a perovskite quantum dot film is placed on a three-dimensional electric translation stage; according to the required array size and spacing, the three-dimensional translation stage is programmed to control the laser movement path; wherein the laser is a 405nm continuous laser with an energy of 7-35mW, a focus position of 0-200µm, and a moving speed of the three-dimensional electric translation stage of 0.1mm / s.

[0012] Preferably, in step 3, a monochrome Micro-LED display chip is combined with the array to complete the color conversion. The specific operation is as follows: through an optical microscope, the array obtained in step 2 is aligned with the Micro-LED display chip, powered on and adjusted to the required brightness, the color conversion is completed, and a patterned display is performed.

[0013] Compared with the prior art, the present invention has the following beneficial effects:

[0014] 1. The present invention is carried out in a general laboratory environment and is easy to operate.

[0015] 2. Compared with other methods, the present invention uses lower cost equipment and the constructed optical path is simple and easy to understand.

[0016] 3. The present invention can prepare arrays of different spacings and sizes according to different setting parameters without a template to meet the requirements of resolution, and no other solvents need to be added during the processing to avoid damaging the material itself.

[0017] 4. The present invention has certain expansibility: 1) Expansion in other materials. By changing the laser and laser energy parameters, it can also be used on other traditional quantum dot materials; 2) Expansion in patterning. In addition to improving the resolution of the array by replacing more precise equipment, it can also directly use laser for patterning without a mask to obtain ultra-high-resolution patterned display, making perovskite quantum dot materials more applicable in AR, VR and other display aspects. BRIEF DESCRIPTION OF THE DRAWINGS

[0018] Figure 1Schematic diagram of the laser processing device.

[0019] Figure 2 (a) is a schematic diagram of the array formed by laser processing of the perovskite quantum dot film, and (b) is the micro-area PL image of the laser-processed area and the laser-unprocessed area.

[0020] Figure 3 Schematic diagram of the color conversion process by combining a monochrome Micro-LED display chip with an array.

[0021] Figure 4 The micrograph and patterned display of the processed perovskite quantum dot film of the present invention.

[0022] Figure 5 (a) is a data graph of laser processing corresponding to different line width intervals at different energies when the moving speed of the three-dimensional translation stage is set to 0.1mm / s and the laser position is set to the focus. (b) is a data graph of laser processing corresponding to different line width intervals at different distances from the focus when the moving speed of the three-dimensional translation stage is set to 0.1mm / s and the laser energy is 35mW.

[0023] Figure 6 Fluorescence microscopy details of Examples 1, 2, and 3.

[0024] Figure 7 Fluorescence microscopy details of Examples 4, 5, and 6. DETAILED DESCRIPTION

[0025] The present invention is further explained below in conjunction with specific test examples. It should be understood that these embodiments are only used to illustrate the present invention and are not used to limit the scope of the present invention. After reading the present invention, various equivalent forms of modifications to the present invention by those skilled in the art all fall within the scope defined by the claims attached to this application.

[0026] The present invention prepares a high-resolution color conversion layer for Micro-LED display based on the photoquenching process of perovskite quantum dot film. This method changes the organizational morphology of the perovskite film by combining with laser processing technology, so that the laser-processed film area completes the photoquenching process, and finally forms an array area of ​​the film. After that, it is combined with a monochrome Micro-LED display chip, and the chip is matched with the color conversion layer array to realize the color conversion process and obtain a color conversion Micro-LED device. This method is easy to operate, low in cost, and has clear boundaries in the laser processing area. It has the potential to prepare higher-resolution arrays. Compared with traditional methods, there is no mass transfer process, which provides support for the further application of perovskite materials in Micro-LED displays.

[0027] Example 1

[0028] The photoquenching and color conversion processing of perovskite quantum dot thin films are carried out according to the preparation process and equipment. The specific process is mainly divided into three steps, and its main experimental equipment and operation process are as follows: Figure 1 , Figure 2 and Figure 3 As shown, the laser is a 405nm continuous laser, the focusing objective lens has a magnification of ×50 and NA0.5, the perovskite quantum dots are CsPbX3 (X=Cl, Br, I), and the ultrasonic cleaning solvent is an acetone solution.

[0029] The specific test steps are as follows:

[0030] Step 1: Prepare a thin film using perovskite quantum dot material on a quartz glass substrate. The steps are as follows:

[0031] Step 1.1: Place the quartz glass substrate in a beaker, add a certain amount of acetone solution into the beaker to submerge the substrate to be cleaned, turn on the ultrasonic cleaning machine, set the power, and perform ultrasonic cleaning on the quartz glass substrate for 30 minutes.

[0032] Step 1.2: Dry the quartz glass substrate cleaned in step 1.1, and then place it in a UV O3 cleaning machine for further cleaning for 20 minutes.

[0033] Step 1.3: Place the quartz glass substrate cleaned in step 1.2 in a coating machine and prepare a thin film using the prepared perovskite quantum dot material.

[0034] Step 1.4: Set the parameters of the glue machine, including the speed of 2000 rpm and the time of 30 seconds.

[0035] Step 1.5: Use tweezers to place the quartz glass substrate on the rotor of the coater, turn on the adsorption button of the coater, and adsorb the quartz glass substrate on the rotor.

[0036] Step 1.6: Use a pipette to quickly drop 60 μL of perovskite quantum dot solution on the quartz glass substrate, and quickly turn on the spin coating button of the coater to make the rotor rotate quickly to form a film.

[0037] Step 2: Use the built platform (such as Figure 1 ), laser treatment of perovskite quantum dot film. The steps are as follows:

[0038] Step 2.1: Use the 3D motorized translation stage control software on the computer to Figure 5 ) to edit the translation stage program and set its moving path, speed and distance from the focal point. The specific control program editing steps are as follows.

[0039] Step 2.1.1: Set the starting position, set the translation stage moving speed, generally 0.1 mm / s, and open the optical path shutter.

[0040] Step 2.1.2: The three-dimensional motorized translation stage moves once in the horizontal direction, the moving distance is set to L, and the optical path shutter is closed.

[0041] Step 2.1.3: The 3D motorized translation stage moves once in the vertical direction, sets the distance to S, and opens the optical path shutter.

[0042] Step 2.1.4: Move the 3D electric translation stage once in the opposite direction of step 2.1.2, set the moving distance to L, and close the optical path shutter.

[0043] Step 2.1.5: The three-dimensional motorized translation stage moves once in the vertical direction, sets the distance to S, and opens the optical path shutter.

[0044] Step 2.1.6: Repeat 2.1.2 to 2.1.5 N times and close the light path shutter.

[0045] Step 2.1.7: Set the 3D motorized translation stage to the starting position and open the optical path shutter.

[0046] Step 2.1.8: The three-dimensional motorized translation stage moves once in the vertical direction, the moving distance is set to L, and the optical path shutter is closed.

[0047] Step 2.1.9: The three-dimensional motorized translation stage moves once in the horizontal direction, sets the distance to S, and opens the optical path shutter.

[0048] Step 2.1.10: Move the 3D motorized translation stage once in the opposite direction of step 2.1.8, set the moving distance to L, and close the optical path shutter.

[0049] Step 2.1.11: The three-dimensional motorized translation stage moves once in the horizontal direction, sets the distance to S, and opens the optical path shutter.

[0050] Step 2.1.12: Repeat 2.1.8 to 2.1.11, repeat N times, and close the optical path shutter. At this point, the film photoquenching process is completed. At this time, the L*L area is (L / S) 2 An array of pixels.

[0051] Step 2.2: Place the sample prepared in step 1 on the three-dimensional electric translation stage.

[0052] Step 2.3: Control the three-dimensional electric translation stage through the computer to move the sample to the preset starting position.

[0053] Step 2.4: Set up the laser and adjust its energy level.

[0054] Step 2.5: The laser light emitted by the laser is reflected by the reflector and introduced into the focusing objective lens so that it is focused on the sample surface.

[0055] Step 2.6: The moving path and speed of the three-dimensional electric translation stage are controlled by a computer program to complete the photoquenching process of the laser on the quantum dot film, thereby forming an array area (such as Figure 2 ).

[0056] Step 3: Take out the sample and combine the array in the sample with the monochrome Micro-LED display chip through an optical microscope to finally complete the color conversion step. The steps are as follows:

[0057] Step 3.1: Use tweezers to take out the sample prepared in step 2 and place it on the monochrome Micro-LED display chip. Use an optical microscope to align the array in the sample with the monochrome Micro-LED display chip (such as Figure 3 ).

[0058] Step 3.2: Power on the monochrome Micro-LED display chip and adjust it to the appropriate brightness.

[0059] Step 3.3: Get the desired light band and make a pattern display (such as Figure 4 ), completing the Micro-LED color conversion process.

[0060] The laser position is set at the focus, the energy is 14mW, and the moving speed of the electric translation stage is 0.1mm / s. Figure 6 (a) is a fluorescence microscopy image of the array, where the array spacing is 1.58 μm.

[0061] Example 2

[0062] The specific process is the same as that of Example 1. The laser position is set to 50 μm from the focal point, the energy is 35 mW, and the moving speed of the electric translation stage is 0.1 mm / s. Figure 6 (b) is a fluorescence microscopy image of the array, where the array spacing is 3.83 μm.

[0063] Example 3

[0064] The specific process is the same as that of Example 1. The laser position is set to 200 μm from the focal point, the energy is 35 mW, and the moving speed of the electric translation stage is 0.1 mm / s. Figure 6 (c) is a fluorescence microscopy image of the array, where the array spacing is 7.76 μm.

[0065] Example 4

[0066] The specific process is the same as that of Example 1. Different pixel center distances S1 are set, the laser position is set to the focal position, the energy is 35mW, and the moving speed of the electric translation stage is 0.1mm / s. Figure 7 (a) in the figure is an array fluorescence microscopy image, in which the pixel density is 508.

[0067] Example 5

[0068] The specific process is the same as that of Example 1. Different pixel center distances S2 are set, the laser position is set to the focal position, the energy is 35mW, and the moving speed of the electric translation stage is 0.1mm / s. Figure 7 (b) is an array fluorescence microscopy image with a pixel density of 1270.

[0069] Example 6

[0070] The specific process is the same as that of Example 1. Different pixel center distances S3 are set. The laser position is set to the focal position. The energy is 35 mW. The moving speed of the electric translation stage is 0.1 mm / s. Figure 7 (c) is a fluorescence microscopy image of the array, where the pixel density is 2540.

Claims

1. A method for processing a Micro-LED color conversion layer based on a perovskite quantum dot film, characterized in that: The following steps are involved: Step 1: In a coating machine, a thin film is prepared on a quartz glass substrate using a perovskite quantum dot solution; Step 2: Processing the perovskite quantum dot film using a laser processing method to form an array; Step 3: Combine a monochrome Micro-LED display chip with the array obtained in step 2 to complete the color conversion.

2. The method according to claim 1, characterized in that In step 1, the perovskite quantum dot solution is spin-coated on a clean silicon dioxide substrate, and a perovskite quantum dot film is obtained after drying, and the film thickness is 25nm±2nm, wherein the spin coating rate is 2000r / min, the time is 45s, and the film is left to dry for more than 24 hours, and the temperature is generally room temperature.

3. The method according to claim 2, characterized in that The perovskite quantum dots are CsPbBr3, the solvent of the perovskite quantum dot solution is toluene, and the concentration of the perovskite quantum dots is 0.135 mmol / ml.

4. The method according to claim 1, characterized in that In step 2, the perovskite quantum dot film is processed by a laser processing method to form an array. The specific process is as follows: the silicon dioxide substrate coated with the perovskite quantum dot film is placed on a three-dimensional electric translation stage; according to the required array size and spacing, the three-dimensional translation stage is programmed to control the laser movement path; the laser is a 405nm continuous laser with an energy of 7-35mW, a focus position of 0-200µm, and a moving speed of the three-dimensional electric translation stage of 0.1mm / s.

5. The method according to claim 1, characterized in that In step 3, a monochrome Micro-LED display chip is combined with the array to complete the color conversion. The specific operations are as follows: through an optical microscope, the array obtained in step 2 is aligned with the Micro-LED display chip, powered on and adjusted to the required brightness, the color conversion is completed, and a patterned display is performed.

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