External-cavity-free near-infrared perovskite laser and preparation method thereof

Abstract

The invention provides a near-infrared perovskite laser without an external cavity and a preparation method thereof. The preparation method of the near-infrared perovskite laser without the external cavity comprises the following steps: dropwise adding a perovskite precursor solution on a substrate; covering a flexible thin film on the substrate, so that the perovskite precursor solution is uniformly distributed between the substrate and the flexible thin film; after the substrate is subjected to standing treatment, the flexible thin film is removed, the perovskite gain dielectric layer is obtained, the flexible thin film is used for inducing the perovskite precursor solution to grow a microcrystalline structure in the process of forming the perovskite gain dielectric layer, and the microcrystalline structure is a resonant cavity of the perovskite gain dielectric layer. According to the preparation method provided by the invention, high-temperature treatment such as heating or thermal annealing is not needed, the preparation process is simple, the cost is low, large-area preparation of the near-infrared perovskite laser without an external resonant cavity can be realized, and adjustment of the emission peak of the laser can be realized by regulating and controlling the components of the perovskite gain material and preparation process parameters.

Description

Technical Field

[0001] The invention relates to the field of perovskite lasers, and in particular to a near-infrared perovskite laser without an external cavity and a preparation method thereof. Background Art

[0002] Near-infrared lasers have important applications in laser communications, laser radar, laser surgery, and optical storage. At present, near-infrared solid-state lasers are mainly based on III-V semiconductor materials, and are usually prepared by methods such as metal-organic chemical vapor deposition and molecular beam epitaxy. They also require the design of complex distributed Bragg reflector (DBR) or distributed feedback (DFB) structures with high-quality resonant cavities, which are complex and costly. Liquid lasers using dyes as gain media can also achieve laser emission in the near-infrared band, but liquid lasers are difficult to meet the requirements of future laser miniaturization and high integration. Therefore, it is of great value to develop near-infrared solid-state lasers that can be prepared by simple solution methods.

[0003] Metal halide perovskite materials have the advantages of being able to be prepared by solution method, adjustable band gap, high purity of luminescent color and high fluorescence quantum yield, and can be used as gain medium materials for lasers. Perovskite lasers, as a new type of laser, have also received widespread attention from scientific researchers in recent years. Lasers based on perovskite films usually require the design of a resonant cavity, which increases the complexity of the process. Lasers based on perovskite microsheets or nanowire structures can use the microsheets or nanowires' own structures to form a whispering gallery cavity or a Fabry-Perot (FP) cavity to achieve gain, but nanomaterial synthesis is required, and usually a single microsheet or nanowire needs to be transferred, making it difficult to achieve large-scale preparation and application. In addition, in some process methods for preparing lasers, high-temperature treatments such as heating or thermal annealing are required, which are not applicable to materials that are not resistant to high temperatures.

[0004] In addition, the research on perovskite lasers is mainly concentrated in the visible light band, especially the green light band, and the research on the near-infrared band is still lacking. Therefore, it is of great significance to develop near-infrared perovskite lasers, especially near-infrared perovskite lasers without external cavities. Summary of the invention

[0005] In view of this, an embodiment of the present invention provides a near-infrared perovskite laser without an external cavity and a method for preparing the same.

[0006] On the one hand, an embodiment of the present invention provides a method for preparing a near-infrared perovskite laser without an external cavity, comprising: dripping a perovskite precursor solution on a substrate; covering the substrate with a flexible film so that the perovskite precursor solution is evenly distributed between the substrate and the flexible film; after the substrate is left to stand for treatment, the flexible film is removed to obtain a perovskite gain medium layer, wherein the flexible film is used to induce the perovskite precursor solution to grow a microcrystalline structure in the process of forming the perovskite gain medium layer, and the microcrystalline structure is a resonant cavity of the perovskite gain medium layer.

[0007] In some embodiments, the perovskite precursor solution is prepared by mixing and stirring a perovskite precursor material and a solvent, wherein the components of the perovskite precursor material include A' y A 1-y SnX3 or A'2A z-1 Sn z X 3z+1 , A' and A are two different organic cations, X is a halogen anion, the size of A' is larger than A, the value range of y is 0~1, z is an integer, and the solvent is volatile.

[0008] In some embodiments, the excitation wavelength of the external cavity-free near-infrared perovskite laser is related to the materials of A', A, X, the values ​​of y, z in the components of the perovskite precursor material and the concentration of the perovskite precursor solution.

[0009] In some embodiments, the material A' in the components of the perovskite precursor material includes phenylethylamine (PEA + ), p-fluorophenylethylamine (pF-PEA + )、m-Fluorophenylethylamine(mF-PEA + )、1-naphthylmethylamine(NMA + ) or butylamine (BA + The material A in the components of the perovskite precursor material includes cesium (Cs + ), methylamine (MA + ) or formamidine (FA + ); the X material in the components of the perovskite precursor material includes Cl － Br － or I － ; The value range of y is 0~0.6, and the value range of z is 3~20.

[0010] In some embodiments, the solvent includes a mixed solution of dimethyl sulfoxide (DMSO) and N,N-dimethylformamide (DMF); and the concentration of the perovskite precursor solution ranges from 0.02 to 1 M.

[0011] In some embodiments, the flexible film controls the volatilization rate of the solvent during the static state of the substrate, thereby inducing the perovskite precursor solution to grow a microcrystalline structure.

[0012] In some embodiments, the flexible film includes a polydimethylsiloxane (PDMS) film, a thermoplastic polyurethane (TPU) film, polyethylene terephthalate (PET), polyethylene naphthalate (PEN), a styrene-ethylene-butylene-styrene block copolymer (SEBS) film, or an ethyl cellulose (EC) film.

[0013] In some embodiments, the substrate includes a flexible substrate or a rigid substrate; before dropping the perovskite precursor solution on the substrate, the preparation method further includes: ultrasonically cleaning the substrate with detergent water, deionized water, acetone and isopropanol solution in sequence, and blowing the substrate dry with nitrogen.

[0014] In some embodiments, after allowing the substrate to stand for a static treatment, removing the flexible film includes: allowing the substrate to stand for a static treatment at room temperature, and then removing the flexible film, wherein the room temperature is 15-35 degrees Celsius.

[0015] On the other hand, an embodiment of the present invention further provides a near-infrared perovskite laser without an external cavity, which is prepared according to the preparation method of the above embodiment, including: a substrate; a perovskite gain medium layer, which is placed on the substrate, and a microcrystalline structure is formed on the perovskite gain medium layer, and the microcrystalline structure is a resonant cavity of the perovskite gain medium layer, wherein the microcrystalline structure includes a plurality of microcrystalline units, and the shape of the microcrystalline unit includes a dendrite shape or a snowflake shape.

[0016] The near-infrared perovskite laser without external cavity and the preparation method thereof provided in the embodiment of the present invention comprises dropping a perovskite precursor solution on a substrate, covering the substrate with a flexible film and then standing the substrate to dry, thereby forming a perovskite gain medium layer with a microcrystalline structure, which has at least the following beneficial effects:

[0017] (1) The method for preparing a near-infrared perovskite laser without an external cavity according to an embodiment of the present invention can make the perovskite precursor solution evenly spread between the flexible film and the substrate by covering the perovskite precursor solution with a flexible film. The covering of the flexible film can induce the perovskite to slowly crystallize at multiple sites, thereby forming a microcrystalline structure with a specific morphology, that is, obtaining a near-infrared perovskite laser without an external resonant cavity;

[0018] (2) The preparation method of the embodiment of the present invention can be carried out at room temperature without heating or thermal annealing, and is applicable to various rigid and flexible substrates, especially to flexible substrates that are not resistant to high temperatures, and is convenient for preparing flexible near-infrared perovskite lasers without external cavities;

[0019] (3) The preparation method of the embodiment of the present invention adopts a full solution method. Compared with the conventional III-V near-infrared laser, which requires an expensive epitaxial growth process, the solution method is simple and low-cost.

[0020] (4) The near-infrared perovskite laser of the present invention does not require the design of an external resonant cavity. Compared with conventional lasers that require the preparation of a complex resonant cavity, the laser structure and preparation process of the present invention are simpler, low-cost, and can be prepared over a large area. In addition, by regulating the perovskite gain material composition, solution concentration, and preparation process conditions, the emission peak of the laser can be adjusted in the near-infrared band of 800-950 nm. BRIEF DESCRIPTION OF THE DRAWINGS

[0021] The above and other objects, features and advantages of the present invention will become more apparent through the following description of the embodiments of the present invention with reference to the accompanying drawings, in which:

[0022] Figure 1 Schematically showing the structure of a near-infrared perovskite laser without an external cavity according to some embodiments of the present invention;

[0023] Figure 2 A flow chart schematically shows a method for preparing a near-infrared perovskite laser without an external cavity according to some embodiments of the present invention;

[0024] Figure 3 Schematically showing the optical microscopic morphology of the perovskite gain medium layer according to an embodiment of the present invention at different perovskite precursor solution concentrations;

[0025] Figure 4 The emission spectra of the near-infrared perovskite laser without external cavity according to an embodiment of the present invention at different perovskite precursor solution concentrations are schematically shown. DETAILED DESCRIPTION

[0026] The following examples are listed and described in detail with the accompanying drawings, but the examples provided are not intended to limit the scope of the present invention. In addition, the drawings are for illustration purposes only and are not drawn to their original size. For ease of understanding, the same elements will be described with the same symbols in the following description.

[0027] The terms "include", "including", "have", etc. used in this document are open terms, which means "including but not limited to".

[0028] In addition, the directional terms mentioned herein, such as "above", "below", etc., are only used to refer to the directions of the drawings and are not used to limit the present invention. Therefore, it should be understood that "above" can be used interchangeably with "below", and when an element such as a layer or film is placed "on" another element, the element can be placed directly on the other element, or there can be an intermediate element. On the other hand, when an element is said to be placed "directly" on another element, there is no intermediate element between the two.

[0029] See also Figure 1 , Figure 1The structure of a near-infrared perovskite laser without external cavity according to some embodiments of the present invention is schematically shown. The near-infrared perovskite laser without external cavity 100 may include a substrate 110 and a perovskite gain medium layer 120 .

[0030] A perovskite gain medium layer 120 is disposed on the substrate 110, and a microcrystalline structure 121 is formed on the perovskite gain medium layer 120. In this article, microcrystalline refers to micron-sized crystals. The microcrystalline structure 121 can be used as a resonant cavity of the perovskite gain medium layer 120. In other words, the perovskite gain medium layer 120 can be used as a gain medium and a resonant cavity of the near-infrared perovskite laser 100 without an external cavity.

[0031] Please continue reading Figure 1 , Figure 1 A partially enlarged top view of the microcrystalline structure 121 is also shown (located at Figure 1 inside the dotted circle), which is equivalent to Figure 1 The view from above to below. It should be noted that Figure 1 The region of the microcrystalline structure 121 shown in the figure is only an example and is not used to limit the position of the microcrystalline structure 121. In fact, the microcrystalline structure 121 can be formed on the entire perovskite gain medium layer 120. In other words, the perovskite gain medium layer 120 has a microcrystalline morphology, and the microcrystalline morphology can be grown when the perovskite gain medium layer 120 is prepared.

[0032] exist Figure 1 In the partially enlarged top view in FIG. 1 , the microcrystalline structure 121 may include a plurality of microcrystalline units 121a and 121b. The shapes of the microcrystalline units 121a and 121b may be snowflake-like (such as microcrystalline unit 121a) or tree-like (such as microcrystalline unit 121b). The shape of the microcrystalline unit refers to the surface morphology of the microcrystalline seen under an optical microscope or a scanning electron microscope. Understandably, Figure 1 The number, size and shape of the microcrystalline units shown are only examples and are not intended to limit the number, size and shape of the microcrystalline units. Microcrystalline structures of different sizes and morphologies can provide different gain effects.

[0033] In this way, the near-infrared perovskite laser 100 without external cavity uses the microcrystalline structure 121 composed of branch-shaped or snowflake-shaped microcrystalline units 121a, 121b as a resonant cavity. It can achieve lasing under optical pumping at room temperature without using an external resonant cavity, which greatly simplifies the device structure and improves the integrability of the laser.

[0034] See also Figure 2 , Figure 2The flowchart of the method for preparing a near-infrared perovskite laser without an external cavity according to some embodiments of the present invention is schematically shown. The method for preparing a near-infrared perovskite laser without an external cavity may include operations S210 to S230.

[0035] In operation S210 , a perovskite precursor solution is dropped on a substrate.

[0036] In operation S220 , a flexible film is covered on the substrate so that the perovskite precursor solution is evenly distributed between the substrate and the flexible film.

[0037] In operation S230, after the substrate is left to stand for processing, the flexible film is removed to obtain a perovskite gain medium layer, wherein the flexible film is used to induce the perovskite precursor solution to grow a microcrystalline structure in the process of forming the perovskite gain medium layer, and the microcrystalline structure is a resonant cavity of the perovskite gain medium layer.

[0038] According to the method for preparing a near-infrared perovskite laser without an external cavity of the embodiment of the present invention, by covering a flexible film on the perovskite precursor solution, the perovskite precursor solution can be evenly spread between the flexible film and the substrate, and the covering of the flexible film can induce the perovskite to slowly crystallize at multiple sites, thereby forming a microcrystalline structure with a specific morphology, that is, a near-infrared perovskite laser without an external resonant cavity is obtained. The preparation method of the embodiment of the present invention can be carried out at room temperature without heating or thermal annealing treatment, and is suitable for various rigid and flexible substrates, especially for flexible substrates that are not resistant to high temperatures, and is convenient for preparing flexible near-infrared perovskite lasers without external cavities. In addition, the preparation method of the embodiment of the present invention is prepared by a full solution method. Compared with the conventional III-V near-infrared laser, which requires an expensive epitaxial growth process, the solution method is simple and low-cost.

[0039] In some embodiments, using Figure 2 The preparation method shown can prepare Figure 1 The near-infrared perovskite laser 100 without external cavity is shown. Figure 1 and Figure 2 The preparation method of the external cavity-free near-infrared perovskite laser 100 is further described.

[0040] Operation S210 is performed to drop a perovskite precursor solution onto the substrate 110 . The perovskite precursor solution is used to form a perovskite gain medium layer 120 having a microcrystalline structure 121 .

[0041] In some embodiments, the substrate 110 may be a rigid substrate, such as a quartz wafer or a silicon wafer. In some embodiments, the substrate 110 may also be a flexible substrate, such as a substrate formed of materials such as polydimethylsiloxane (PDMS), polyethylene terephthalate (PET), polyethylene naphthalate (PEN) or polyimide (PI). Since the preparation method provided by the embodiment of the present invention can be carried out at room temperature without high temperature heating or thermal annealing, the substrate 110 can be a flexible substrate that is not resistant to high temperatures, which is suitable for preparing a flexible laser. The room temperature is generally 15 to 35 degrees Celsius.

[0042] In some embodiments, the perovskite precursor solution can be prepared by mixing and stirring the perovskite precursor material and the solvent. Perovskite generally refers to a class of compounds with the general formula ABX3, usually A refers to a monovalent cation, B refers to a divalent metal cation, and X refers to a halogen anion. In an embodiment of the present invention, the excitation wavelength of the near-infrared perovskite laser 100 without an external cavity can be adjusted by changing the composition of the perovskite precursor material, that is, changing the composition and proportion of A, B, and X in the traditional ABX3 structure to achieve different emission wavelengths.

[0043] Specifically, the components of the perovskite precursor material in this embodiment may include A' y A 1-y SnX3 or A'2A z- 1Sn z X 3z+1 . A' and A are two different organic cations, the size of A' is larger than A, the value range of y is 0~1, and the combination of A' and A is equivalent to A in the traditional ABX3 structure. The introduction of the larger cation A' can reduce the perovskite from a three-dimensional structure to a mixture of two-dimensional and three-dimensional perovskite phases, forming a quasi-two-dimensional structure, which can effectively hinder the entry of oxygen and water molecules, prevent the discharge of decomposition products, and improve the long-term stability of the perovskite film. At the same time, the exciton binding energy of the quasi-two-dimensional perovskite is large, which is conducive to improving the luminescence performance of the perovskite film. Sn (tin) corresponds to B in the traditional ABX3 structure. Compared with the perovskite material with Pb as the B position, the introduction of Sn can narrow the band gap of the metal halide perovskite material, red-shift the luminescence peak, and achieve luminescence in the near-infrared region. X is a halogen anion, and z is an integer.

[0044] In some embodiments, A' y A 1-y SnX3 or A'2A z-1 Sn z X 3z+1 A can be cesium (Cs + ), methylamine (MA + ), formamidine (FA +) or a combination of one or more thereof; A' may be phenylethylamine (PEA + ), p-fluorophenylethylamine (pF-PEA + )、m-Fluorophenylethylamine(mF-PEA + )、1-naphthylmethylamine(NMA + ), butylamine (BA + ) in one or more combinations; X can be Cl － Br － ,I － The value range of y can be further set to 0~0.6, where y can be equal to 0 or 0.6. The value range of z can be further set to 3~20, where z can be equal to 3 or 20. By changing A' y A 1-y SnX3 or A'2A z-1 Sn z X 3z+1 The material of A′, the materials of A and X, and the values ​​of y and z can adjust the band gap of the perovskite, thereby achieving the adjustment of the excitation wavelength of the near-infrared perovskite laser 100 without external cavity.

[0045] In the present embodiment, the perovskite precursor solution also contains a volatile solvent. During the volatilization process of the solvent, the perovskite can crystallize at multiple sites, and different volatilization rates can obtain crystals of different morphologies. By changing the ratio of the solvent to the perovskite precursor material, or simply changing the amount of solvent added, perovskite precursor solutions of different concentrations can be prepared. By adjusting the concentration of the perovskite precursor, the crystal morphology of the perovskite can be regulated, thereby enabling the adjustment of the lasing peak. In other words, the excitation wavelength of the external cavity-free near-infrared perovskite laser 100 is related to the materials of A', A, X and the values ​​of y and z in the components of the perovskite precursor material and the concentration of the perovskite precursor solution.

[0046] In some embodiments, the solvent may include a mixed solution of dimethyl sulfoxide (DMSO) and N,N-dimethylformamide (DMF), and the volume ratio of the two may be DMF:DMSO=4:1. The concentration range of the perovskite precursor solution is 0.02~1 M, for example, it may be 0.2 M, 0.4 M or 1 M. The solvent and the perovskite precursor material may be placed in a specific container, stirred by magnetic force for 12 hours, and a uniformly mixed perovskite precursor solution may be obtained, which is then dropped onto the cleaned substrate 110. Next, operation S220 is performed.

[0047] In operation S220 , a flexible film is covered on the substrate 110 , so that the perovskite precursor solution is evenly distributed between the substrate 110 and the flexible film.

[0048] In some embodiments, the flexible film includes, but is not limited to, a polydimethylsiloxane (PDMS) film, a thermoplastic polyurethane (TPU) film, a polyethylene terephthalate (PET), a polyethylene naphthalate (PEN), a styrene-ethylene-butylene-styrene block copolymer (SEBS) film, or an ethyl cellulose (EC) film. Taking a PDMS film with a thickness of 0.02 to 1 mm and a flat surface as an example, it has good flexibility and stretchability. After covering the substrate 110, it can closely fit the substrate 110 and the perovskite precursor solution, so that the perovskite precursor solution is evenly distributed between the substrate 110 and the PDMS film. Next, operation S230 is performed.

[0049] In operation S230 , after the substrate 110 is left to stand for a period of time, the flexible film is removed to obtain the perovskite gain medium layer 120 .

[0050] Specifically, the substrate 110 covered with the film can be placed at room temperature of 15 to 35 degrees Celsius and allowed to stand for 8 to 24 hours. During the standing process, the flexible film can slow down the volatilization rate of the solvent in the perovskite precursor solution, thereby inducing multi-site slow crystallization of the perovskite. Then remove the flexible film, and the perovskite gain medium layer 120 can be obtained, and microcrystalline units 121a and 121b on the microcrystalline structure 121 are formed. It can be seen that this embodiment does not require heating or thermal annealing treatment, and does not require an external solvent atmosphere. The perovskite gain medium layer 120 can be obtained by simply covering the flexible film and standing it at room temperature, thereby completing the preparation of the near-infrared perovskite laser 100 without an external cavity.

[0051] In some extended embodiments, after operation S230, an isolation layer (not shown in the figure) may be further covered on the perovskite gain medium layer 120. The isolation layer may isolate the perovskite layer from water, oxygen and external solvent atmosphere, significantly improving the stability of the perovskite film. As an example, the isolation layer may be polymethyl methacrylate or NOA UV curing glue, but the present invention is not limited thereto.

[0052] Example

[0053] (1) Prepare perovskite precursor solution

[0054] Three different concentrations of PEA were prepared x FA 1-xSnI3 perovskite precursor solution. PEAI, FAI, SnI2, SnF2 were weighed in a molar ratio of 0.15:0.85:1:0.075 and placed in a sample bottle. Then a mixed solution of DMF and DMSO was added, with a volume ratio of DMF:DMSO = 4:1. By controlling the amount of DMF and DMSO mixed solution added, the solution concentrations were adjusted to 0.4 M, 0.2 M, and 0.1 M, respectively. Magnetic stirring was performed for 12 hours to obtain a perovskite precursor solution.

[0055] (2) Preparation of perovskite lasers

[0056] First, the substrate was cleaned by ultrasonic cleaning with detergent water, deionized water, acetone and isopropanol solution for 20 minutes, and then dried with nitrogen.

[0057] Then the substrate was moved into a nitrogen glove box, 10 μL of perovskite precursor solution was dripped onto the substrate, and then a flat PDMS film was covered onto the substrate, so that the perovskite precursor solution was evenly spread between the quartz substrate and the PDMS to form a liquid film. After being placed at room temperature for 12 hours, the PDMS film was removed from the substrate, and a perovskite gain medium layer was obtained on the upper surface of the substrate, completing the preparation of the perovskite laser.

[0058] See also Figure 3 and Figure 4 , Figure 3 The optical microscopic morphology of the perovskite gain medium layer according to an embodiment of the present invention at different perovskite precursor solution concentrations (0.4 M, 0.2 M and 0.1 M) is schematically shown. Figure 4 The emission spectra of the external cavity-free near-infrared perovskite laser according to an embodiment of the present invention at different perovskite precursor solution concentrations (0.4 M, 0.2 M and 0.1 M) are schematically shown.

[0059] like Figure 3 As shown, the optical microscopic morphology of the perovskite gain medium layer according to the embodiment of the present invention presents a large number of dendrite-shaped or snowflake-shaped microcrystals, which spontaneously form a resonant cavity without the need for an external resonant cavity. The morphologies of different solution concentrations (0.4 M, 0.2 M, and 0.1 M, respectively) are different, and microcrystal regions of different sizes and morphologies can provide different gain effects.

[0060] like Figure 4As shown, the horizontal axis represents wavelength (wavelength), the unit is nm, and the vertical axis represents normalized intensity (normalized intensity), the unit is au. It can be seen that, with the near-infrared perovskite laser without external cavity provided by the embodiment of the present invention, as the concentration of the perovskite precursor solution decreases, the emission peak blue shifts, that is, the maximum emission peak wavelength moves to the short wave. It means that without changing the perovskite component, the laser emission peak can be adjusted by simply adjusting the concentration of the perovskite precursor solution.

[0061] At this point, an external cavity-free near-infrared perovskite laser and its preparation method have been introduced. According to multiple embodiments, the preparation method of the external cavity-free near-infrared perovskite laser provided by the present invention can make the perovskite precursor solution evenly spread between the flexible film and the substrate by covering the perovskite precursor solution with a flexible film. The covering of the flexible film can induce the multi-site slow crystallization of the perovskite, thereby forming a microcrystalline structure with a specific morphology, that is, a near-infrared perovskite laser without an external resonant cavity is obtained; the preparation method of the embodiment of the present invention can be carried out at room temperature without heating or thermal annealing treatment, and is suitable for various rigid and flexible substrates, especially for flexible substrates that are not resistant to high temperatures, and is easy to prepare. Flexible near-infrared perovskite laser without external cavity; the preparation method of the embodiment of the present invention adopts a full solution method. Compared with the conventional III-V group near-infrared laser that needs to adopt an expensive epitaxial process for growth, the solution method is simple and low-cost; the laser of the present invention does not need to design an external resonant cavity. Compared with the conventional laser that needs to prepare a complex resonant cavity, the laser structure and preparation process of the present invention are simpler, low-cost, and can be prepared over a large area. By regulating the perovskite gain material component, solution concentration and preparation process conditions, the emission peak of the laser can be adjusted in the near-infrared band of 800-950 nm.

[0062] In summary, although the present invention has been disclosed as above by way of embodiments, it is not intended to limit the present invention. A person skilled in the art to which the present invention belongs may make various changes and modifications without departing from the spirit and scope of the present invention. Therefore, the protection scope of the present invention shall be determined by the definition of the attached claims.

Claims

1. A method for preparing a near-infrared perovskite laser without an external cavity, characterized in that: include: Dropping a perovskite precursor solution on the substrate; Covering the substrate with a flexible film so that the perovskite precursor solution is evenly distributed between the substrate and the flexible film; After the substrate is left to stand for treatment, the flexible film is removed to obtain a perovskite gain medium layer. The flexible film is used to induce the perovskite precursor solution to grow a microcrystalline structure during the process of forming the perovskite gain medium layer, and the microcrystalline structure is the resonant cavity of the perovskite gain medium layer.

2. The preparation method according to claim 1, characterized in that: The perovskite precursor solution is prepared by mixing and stirring a perovskite precursor material and a solvent. Wherein, the components of the perovskite precursor material include A' y A 1-y SnX3 or A'2A z-1 Sn z X 3z+1 , A' and A are two different organic cations, X is a halogen anion, the size of A' is larger than A, the value range of y is 0~1, and z is an integer. The solvent is volatile.

3. The preparation method according to claim 2, characterized in that: The excitation wavelength of the near-infrared perovskite laser without external cavity is related to the materials of A', A, X and the values ​​of y and z in the components of the perovskite precursor material and the concentration of the perovskite precursor solution.

4. The preparation method according to claim 2, characterized in that: The material A' in the components of the perovskite precursor material includes phenylethylamine (PEA + ), p-fluorophenylethylamine (pF-PEA + )、m-Fluorophenylethylamine(mF-PEA + )、1-naphthylmethylamine(NMA + ) or butylamine (BA + ); The material A in the components of the perovskite precursor material includes cesium (Cs + ), methylamine (MA + ) or formamidine (FA + ); The material X in the components of the perovskite precursor material includes Cl － Br － or I － ; The value range of y is 0~0.6, and the value range of z is 3~20.

5. The preparation method according to claim 2, characterized in that: The solvent includes a mixed solution of dimethyl sulfoxide (DMSO) and N,N-dimethylformamide (DMF); the concentration range of the perovskite precursor solution is 0.02-1 M.

6. The preparation method according to claim 2, characterized in that: The flexible film controls the volatilization rate of the solvent during the static state of the substrate, thereby inducing the perovskite precursor solution to grow the microcrystalline structure.

7. The preparation method according to claim 6, characterized in that: The flexible film includes a polydimethylsiloxane (PDMS) film, a thermoplastic polyurethane (TPU) film, a polyethylene terephthalate (PET), a polyethylene naphthalate (PEN), a styrene-ethylene-butylene-styrene block copolymer (SEBS) film or an ethyl cellulose (EC) film.

8. The preparation method according to claim 1, characterized in that: The substrate comprises a flexible substrate or a rigid substrate; Before the perovskite precursor solution is dripped onto the substrate, the preparation method further comprises: The substrate was ultrasonically cleaned with detergent water, deionized water, acetone and isopropanol solution in sequence, and the substrate was blown dry with nitrogen gas.

9. The preparation method according to claim 1, characterized in that: After the substrate is left to stand for processing, removing the flexible film comprises: After the substrate is left to stand at room temperature, the flexible film is removed, wherein the room temperature is 15-35 degrees Celsius.

10. A near-infrared perovskite laser without external cavity, prepared by the preparation method according to any one of claims 1 to 9, characterized in that: include: substrate; A perovskite gain medium layer is disposed on the substrate, a microcrystalline structure is formed on the perovskite gain medium layer, and the microcrystalline structure is a resonant cavity of the perovskite gain medium layer. The microcrystalline structure includes a plurality of microcrystalline units, and the shape of the microcrystalline units includes a dendrite shape or a snowflake shape.

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