A full-color fluorescent film patterning method based on laser transfer

Abstract

The present invention discloses a full-color fluorescent film patterning method based on laser transfer, which belongs to the technical field of photoelectric device preparation. The specific steps are as follows: Step (1): Preparation of a carrier substrate and a receiving substrate; Step (2): Laser transfer; The present invention uses laser to focus on a carrier substrate spin-coated with a fluorescent material, and transfers red, green and blue fluorescent materials from the carrier substrate to the receiving substrate through the action of the laser, and finally obtains a full-color fluorescent pattern on the carrier substrate. The process of laser transfer of the full-color fluorescent film does not involve the use of a sacrificial layer, which reduces the residue of the sacrificial layer on the transfer material, simplifies the preparation process, and can further improve the transfer accuracy. The process is a contactless process and will not cause pollution to the transferred fluorescent material.

Description

Technical Field

[0001] The present invention belongs to the technical field of optoelectronic device preparation, and specifically involves transferring red, green and blue quantum dots spin-coated on a carrier substrate to a receiving substrate by using a femtosecond laser, and forming a full-color fluorescent film pattern through multiple precise transfers, thereby providing a new strategy for preparing high-precision full-color fluorescent patterns. Background Art

[0002] With the rapid development of fluorescent materials such as quantum dots, various new fluorescent materials have important applications in display, laser, anti-counterfeiting and information storage. This is also due to the advantages of these fluorescent materials such as adjustable emission wavelength, excellent color purity, high photoluminescence quantum yield and simple solution processability. However, it is still a challenge to achieve high-resolution full-color patterning of fluorescent materials, mainly due to the limitations of existing patterning technology itself and the physical and chemical properties of the materials.

[0003] At present, the photolithography method is to mix quantum dots and other fluorescent materials with photoresist, and then remove the photoresist through development after the mask is exposed, and finally obtain patterned mineral quantum dots. However, the performance of the fluorescent material will generally be affected during the development process. The inkjet printing method is to spray the ink made of fluorescent material onto the substrate through the nozzle, and finally realize the preparation of patterned fluorescent materials. However, the whole process will be limited by the viscosity of the ink and the capacity of the nozzle, and the patterning accuracy is difficult to further improve. The seal transfer method is to use the template as a seal and the fluorescent material as ink. When they are in contact with each other, the perovskite quantum dots can be patterned and transferred to the substrate, but the deformation of the template under pressure will obviously limit the repeatability and fidelity, and the preparation of full-color fluorescent patterns also involves a complex alignment process.

[0004] In summary, the existing preparation processes have problems such as complex operation, difficulty in ensuring the alignment of high-precision full-color arrays, impact on the performance of fluorescent materials, and difficulty in further improving patterning accuracy, which limit the application of full-color fluorescent materials. Summary of the invention

[0005] In view of the shortcomings of the prior art, the technical problem to be solved by the present invention is to provide a method for patterning a full-color fluorescent film by laser transfer. That is, the laser is focused on a carrier substrate coated with fluorescent materials, and the red, green and blue fluorescent materials are transferred from the carrier substrate to the receiving substrate by the action of the laser, and finally a full-color fluorescent pattern is obtained on the carrier substrate. The main principle is: under the action of a femtosecond laser, the fluorescent film on the carrier substrate is transferred to the receiving substrate. In the process of fluorescent film peeling and transfer, the driving force mainly comes from three sources: 1. First, after the fluorescent film undergoes nonlinear absorption, a large number of electrons are excited, and the electron temperature rises sharply; when the electron energy reaches the threshold of escape, a plasma including hot electrons and cold ions is formed and begins to expand, providing a driving force for quantum dot transfer; 2. The unannealed fluorescent film contains a small amount of solvent, and the existing solvent also absorbs the laser radiation energy and evaporates rapidly and expands in volume, thereby assisting in driving the expansion and transfer of the fluorescent film; 3. The fluorescent film spin-coated on the carrier substrate is placed upside down on the displacement table, and the peeled fluorescent film will be transferred to the receiving substrate under the action of its own gravity.

[0006] The present invention is achieved through the following technical solutions:

[0007] A full-color fluorescent film patterning method based on laser transfer, the specific steps are as follows:

[0008] (1) Preparation of carrier substrate and receiving substrate;

[0009] The specific steps are as follows: first, clean glass is wiped with cotton balls alternately using deionized water and anhydrous ethanol, and dried naturally in a closed space; then the fluorescent material solution is spin-coated on a glass substrate as a carrier substrate, and no other sacrificial layer is required between the glass substrate and the fluorescent material film; and the receiving substrate is a clean glass sheet;

[0010] (2) Laser transfer;

[0011] The specific steps are as follows: first, place the receiving substrate on the side of the carrier substrate coated with the fluorescent material film and fit it tightly to prevent the distortion of the pattern during the transfer process; then, invert the entire sample and fix it on the displacement platform so that the laser is focused directly on the fluorescent film of the carrier substrate, and the laser is used to induce the material to peel off and transfer to the receiving substrate; after the fluorescent material absorbs the laser energy, plasma expansion occurs, and at the same time, the solvent in the unannealed fluorescent film evaporates and expands, which together with gravity provides the power for the transfer of the fluorescent film; the relative position of the receiving substrate and the laser is kept unchanged, and different carrier substrates are replaced according to the color of the film to be deposited, and the transfer is repeated; finally, a high-precision full-color patterned fluorescent film can be obtained on the receiving substrate by laser scanning.

[0012] Furthermore, the size of the glass used in step (1) is 50*25*0.2 mm; the cotton ball used is a medical absorbent cotton ball; the fluorescent material includes perovskite quantum dots and inorganic Cd-based quantum dot solution, and the concentration of the quantum dots is 25 mg / ml; 0.01-0.2 mL of single-color quantum dots are obtained each time; the spin coating speed is 1000-3000 rpm, and the spin coating time is 30s-50s.

[0013] Furthermore, the perovskite quantum dots include red light (CsPb (Br 0.35 I 0.65 )3), green light (CsPbBr3) and blue light (CsPb(Br 0.35 Cl 0.65 )3) Perovskite quantum dots; Inorganic Cd-based quantum dots include red light (CdZnSe / CdZnS / ZnS), green light (CdZnSe / CdZnS / ZnS) and blue light (CdZnSe / ZnSeS / ZnS) quantum dots, and the quantum dots were purchased from Suzhou Xingshuo Nanotechnology Co., Ltd.

[0014] Furthermore, the laser in step (2) is a femtosecond laser with a wavelength of 343-1030 nm and a pulse frequency of 1-500 kHz. The laser power required for the experiment is 10-200 mW, the scanning speed is 0.1-2 mm / s, and a 40x objective lens is used for focusing, and its numerical aperture is 0.65.

[0015] Furthermore, the optical path of the laser is: first, the femtosecond laser emitted by the laser passes through the first convex lens and the light gate and then expands the beam through the second convex lens to expand the light spot, and then sequentially passes through the first total reflection mirror, the second total reflection mirror, the third convex lens and the fourth convex lens to shape the beam, and then sequentially passes through the attenuation plate, the first half-reflective half-mirror and the objective lens to focus and then enter the sample to be processed.

[0016] Furthermore, the laser scanning direction adopts a line-by-line scanning method for laser transfer, which is as follows: first, according to the designed pattern, it is converted into a program recognizable by the laser, the line spacing is set to 0.1-5μm, and the laser scanning speed is 0.1×10 -3 -2×10 -3 m / s.

[0017] Compared with the prior art, the present invention has the following advantages:

[0018] (1) The laser transfer method can quickly obtain a controllable, high-precision full-color patterned fluorescent film, which has great application potential in the fields of displays, anti-counterfeiting labels, etc.

[0019] (2) Laser transfer technology can integrate patterning, transfer, deposition, and multiple color alignment into one step. The preparation process is simple and efficient, which can meet the needs of commercial applications.

[0020] (3) The process of preparing full-color fluorescent film by laser transfer is a non-contact process and will not cause pollution to the transferred fluorescent material;

[0021] (4) The process of laser transfer of full-color fluorescent film does not involve the use of a sacrificial layer, which reduces the residue of the sacrificial layer on the transfer material, simplifies the preparation process, and can further improve the transfer accuracy. BRIEF DESCRIPTION OF THE DRAWINGS

[0022] Figure 1 A schematic diagram of a process of preparing a full-color patterned fluorescent film by laser transfer according to the present invention;

[0023] Figure 2 This is an optical photograph of bubbles generated in a solvent by focusing a laser that reaches the laser transfer threshold of the present invention;

[0024] Since there is only a small amount of solvent in the fluorescent film, it is difficult to observe the phenomenon of laser-induced solvent evaporation during the laser transfer process. In order to prove that the laser power has reached the evaporation threshold of the solvent, the femtosecond laser is directly focused into the solvent and the generation of bubbles is observed.

[0025] Figure 3 The fluorescence microscope photos of the patterned quantum dot film transferred under the inverted and non-inverted film of the present invention;

[0026] Figure 4 The fluorescence microscope photos of the patterned quantum dot film transferred at different laser powers and scanning speeds of the present invention;

[0027] Figure 5 Scanning electron microscope photos and fluorescence microscope photos of the invention using laser to transfer the quantum dot film on the carrier substrate to the receiving substrate;

[0028] Wherein: a is a scanning electron microscope photo of a carrier substrate for preparing a quantum dot array with a width of 1.8 μm, b is a high-magnification scanning electron microscope photo of a carrier substrate for preparing a quantum dot array with a width of 1.8 μm, and c is a fluorescence microscope photo of a quantum dot film with an array with a width of 1.8 μm on a receiving substrate;

[0029] Figure 6 The fluorescence microscope photographs of full-color quantum dot film arrays of different sizes prepared by multiple transfers in the present invention;

[0030] Wherein: a is a fluorescence microscope photograph of a laser-transferred red, green and blue light fluorescent array with a width of 20 μm, b is a fluorescence microscope photograph of a laser-transferred red, green and blue light fluorescent array with a width of 1.8 μm, and c is a high-magnification fluorescence microscope photograph of a laser-transferred red, green and blue light fluorescent array with a width of 1.8 μm;

[0031] Figure 7 This is a fluorescence microscope photo of the patterned full-color quantum dot film transferred by the present invention;

[0032] Among them: a is a fluorescence microscope photo of a full-color sunflower prepared by laser transfer, and b is a fluorescence microscope photo of a full-color flower prepared by laser transfer. DETAILED DESCRIPTION

[0033] The specific implementation of the present invention is described in detail below in conjunction with the accompanying drawings. It should be understood that the specific implementation described here is only used to illustrate and explain the present invention, and is not used to limit the present invention.

[0034] Example 1

[0035] Method for preparing high-precision full-color patterned quantum dot film using laser transfer

[0036] The method of the present invention is to first spin-coat quantum dot films of different colors on a pre-prepared glass carrier substrate, and the spin-coated quantum dot films do not need to be annealed. The prepared carrier substrate with a fluorescent material film is directly and tightly attached to the receiving substrate, and there is almost no distance between the carrier substrate and the receiving substrate, thereby preventing the distortion of the pattern during the transfer process; then, the entire sample is fixed on a displacement platform and a computer program is used to control the laser to focus directly on the fluorescent film of the carrier substrate to induce pattern transfer; the most commonly used femtosecond laser transfer dynamics explanation is the plasma expansion model combined with the dual-temperature model. After the fluorescent film undergoes nonlinear absorption, a large number of electrons are excited and the electron temperature rises sharply. Due to the ultrashort pulse of the femtosecond laser, the electron energy does not have enough time to be transferred to the ions through electron-phonon coupling. When the electron energy reaches the escape threshold, a plasma including hot electrons and cold ions is formed and begins to expand, providing a driving force for quantum dot transfer. It should be pointed out that the unannealed fluorescent film contains a small amount of solvent, and the presence of the solvent also absorbs the laser radiation energy and evaporates rapidly and expands in volume, thereby assisting in driving the fluorescent film to expand and transfer. Keep the positions of the receiving substrate and the laser unchanged, change the light-emitting type of the fluorescent film on the carrier substrate, and repeat the transfer; finally, a high-precision full-color patterned fluorescent film can be obtained on the receiving substrate.

[0037] like Figure 1 As shown, this embodiment provides a method for preparing high-precision patterned perovskite quantum dots using laser, and the specific steps are as follows:

[0038] (1) Preparation of substrate: The substrate used is a glass substrate with a size of 50*25*0.2 mm. First, the glass sheet is wiped six times with deionized water and 99.5% anhydrous ethanol prepared in the laboratory, and then the wiped glass sheet is naturally dried in a dark closed space. A trace amount of 0.01-0.2 mL of fluorescent material solution is spin-coated on the glass substrate as a carrier substrate, and a clean glass sheet is used as a receiving substrate.

[0039] The fluorescent material solution includes perovskite quantum dots and inorganic Cd-based quantum dots solution, and the concentration of quantum dots is 25 mg / ml; 0.01 mL of single-color quantum dots are obtained each time; the spin coating speed is 1000 rpm, and the spin coating time is 30 s;

[0040] Wherein, the perovskite quantum dots include red light (CsPb (Br 0.35 I 0.65 )3), green light (CsPbBr3) and blue light (CsPb(Br 0.35 Cl 0.65 )3) Perovskite quantum dots; Inorganic Cd-based quantum dots include red light (CdZnSe / CdZnS / ZnS), green light (CdZnSe / CdZnS / ZnS) and blue light (CdZnSe / ZnSeS / ZnS) quantum dots, and the quantum dots were purchased from Suzhou Xingshuo Nanotechnology Co., Ltd.

[0041] (2) Laser transfer;

[0042] The specific steps are as follows: place the receiving substrate on the side of the carrier substrate coated with the fluorescent material film and fit it tightly to prevent the distortion of the pattern during the transfer process; then, invert the entire sample and fix it on the displacement platform;. By adjusting the focusing position of the laser, the laser is focused on the quantum dot film on the carrier substrate. First, according to the designed structure and line scanning method, the quantum dot film is scanned at a scanning speed of 0.1mm / s, 0.2mm / s, 0.4mm / s, 0.8mm / s, 1.6mm / s, and a line spacing of 0.1mm. The wavelength of the femtosecond laser used in this process is 1030nm, the pulse frequency is 1kHz, and the laser power required for the experiment is 10mW, 50mW, and 100mW, respectively. During the processing, it is necessary to ensure that the glass substrate is perpendicular to the laser optical axis. The patterned preparation of full-color fluorescent materials requires that the relative position of the carrier substrate and the laser remain unchanged, and the carrier substrate is replaced according to the color of the film to be deposited. Repeat the transfer process, and finally a full-color patterned fluorescent film will be obtained on the receiving substrate.

[0043] In this embodiment, the laser optical path is: first, the femtosecond laser emitted by the laser passes through the first convex lens and the light gate and then expands the beam through the second convex lens to expand the light spot, and then sequentially passes through the first total reflection mirror, the second total reflection mirror, the third convex lens and the fourth convex lens to shape the beam, and then sequentially passes through the attenuation plate, the first half-reflective half-mirror and the objective lens to focus and then is incident on the sample to be processed.

[0044] Depend on Figure 1 It can be seen that on the glass substrate, the quantum dot film spin-coated on the carrier substrate does not need to be annealed, and the carrier substrate with the fluorescent film is inverted, so as to ensure that the quantum dot film peeled off by the laser is transferred to the receiving substrate under its own gravity. And the entire transfer process integrates patterning, transfer, deposition, and alignment in one step, and the pre-designed full-color patterned fluorescent film can be directly obtained on the substrate.

[0045] Depend on Figure 2 It can be seen that during the femtosecond laser transfer process, the unannealed fluorescent film contains a small amount of solvent that has not evaporated in time. The solvent will also absorb the laser radiation energy, and then evaporate and expand rapidly, thereby assisting the transfer of the laser-peeled fluorescent film. Since there is only a small amount of solvent in the fluorescent film, it is difficult to observe the phenomenon of laser-induced solvent evaporation during the laser transfer process. In order to prove that the laser power has reached the evaporation threshold of the solvent, the femtosecond laser is directly focused on the solvent, and the generation of bubbles is observed.

[0046] Depend on Figure 3 It can be seen that the patterned quantum dot film transferred in the inverted state has clear edges and uniform fluorescence properties, indicating that the gravity of the peeled film itself does provide power during the transfer process.

[0047] Depend on Figure 4 It can be seen that at low laser power, the laser energy is insufficient to transfer all the quantum dots in the scanned area, and the scanning speed must also be within an appropriate range to achieve a complete patterned fluorescent film on the receiving substrate.

[0048] Depend on Figure 5 It can be seen that the quantum dot films of different sizes transferred from the receiving substrate all have clear edges, and the size of the area scanned by the laser on the carrier substrate is consistent with the size on the receiving substrate, so the femtosecond laser transfer technology has good fidelity.

[0049] Depend on Figure 6 It can be seen that femtosecond laser can achieve high-precision transfer while directly realizing the preparation of full-color high-precision red, green and blue pixel arrays without the need for alignment and mask.

[0050] Depend on Figure 7 It can be seen that due to the digital processing characteristics of femtosecond laser, complex full-color patterned fluorescent films can be prepared, such as Figure 7The full-color fluorescence microscope photo of a sunflower is shown in a. Figure 7 b is a fluorescence microscopy photograph of a full-color flower.

Claims

1. A full-color fluorescent film patterning method based on laser transfer, characterized in that: The specific steps are as follows: (1) Preparation of carrier substrate and receiving substrate; The specific steps are as follows: first, clean glass is wiped with cotton balls alternately using deionized water and anhydrous ethanol, and dried naturally in a closed space; then the fluorescent material solution is spin-coated on a glass substrate as a carrier substrate, and no other sacrificial layer is required between the glass substrate and the fluorescent material film; and the receiving substrate is a clean glass sheet; (2) Laser transfer; The specific steps are as follows: first, place the receiving substrate on the side of the carrier substrate coated with the fluorescent material film and fit it tightly to prevent the distortion of the pattern during the transfer process; then, invert the entire sample and fix it on the displacement platform so that the laser is focused directly on the fluorescent film of the carrier substrate, and the laser is used to induce the material to peel off and transfer to the receiving substrate; after the fluorescent material absorbs the laser energy, plasma expansion occurs, and at the same time, the solvent in the unannealed fluorescent film evaporates and expands, which together with gravity provides the power for the transfer of the fluorescent film; the relative position of the receiving substrate and the laser is kept unchanged, and different carrier substrates are replaced according to the color of the film to be deposited, and the transfer is repeated; finally, a high-precision full-color patterned fluorescent film can be obtained on the receiving substrate by laser scanning.

2. A full-color fluorescent film patterning method based on laser transfer as claimed in claim 1, characterized in that: The glass size of step (1) is 50*25*0.2 mm; the cotton ball used is a medical absorbent cotton ball; the fluorescent material includes perovskite quantum dots and inorganic Cd-based quantum dot solution, and the concentration of the quantum dots is 25 mg / ml; 0.01-0.2 mL of single-color quantum dots are obtained each time; the spin coating speed is 1000-3000 rpm, and the spin coating time is 30s-50s.

3. A full-color fluorescent film patterning method based on laser transfer as claimed in claim 2, characterized in that: The perovskite quantum dots include red CsPb (Br 0.35 I 0.65 )3. Green CsPbBr3 and blue CsPb(Br 0.35 Cl 0.65 )3 Perovskite quantum dots; Inorganic Cd-based quantum dots include red light CdZnSe / CdZnS / ZnS, green light CdZnSe / CdZnS / ZnS and blue light CdZnSe / ZnSeS / ZnS quantum dots, and the quantum dots were purchased from Suzhou Xingshuo Nanotechnology Co., Ltd.

4. A full-color fluorescent film patterning method based on laser transfer as claimed in claim 1, characterized in that: The laser in step (2) is a femtosecond laser with a wavelength of 343-1030nm and a pulse frequency of 1-500kHz. The laser power required for the experiment is 10-200mW, the scanning speed is 0.1-2mm / s, and a 40x objective lens is used for focusing, and its numerical aperture is 0.

65.

5. The full-color fluorescent film patterning method based on laser transfer according to claim 1, characterized in that: The optical path of the laser in step (2) is as follows: first, the femtosecond laser emitted by the laser passes through the first convex lens and the light gate and then through the second convex lens to expand the light spot, and then passes through the first total reflection mirror, the second total reflection mirror, the third convex lens and the fourth convex lens in sequence to shape the beam, and then passes through the attenuation plate, the first half-reflecting half-mirror and the objective lens in sequence to focus and then enter the sample to be processed.

6. A full-color fluorescent film patterning method based on laser transfer as claimed in claim 1, characterized in that: In step (2), the laser scanning direction is laser transferred by line scanning, specifically as follows: first, according to the designed pattern, it is converted into a program that can be recognized by the laser, the line spacing is set to 0.1-5μm, and the laser scanning speed in the horizontal direction is 0.1×10 -3 -2×10 -3 m / s.

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