Extracavity near-infrared perovskite laser and preparation method thereof

Abstract

The application provides a kind of external cavity-free near-infrared perovskite laser and its preparation method.The preparation method of the external cavity-free near-infrared perovskite laser includes: dropping perovskite precursor solution on a substrate;covering a flexible film on the substrate to make the perovskite precursor solution uniformly distributed between the substrate and the flexible film;after the substrate is placed and treated, 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 into a microcrystalline structure during the formation of the perovskite gain medium layer, and the microcrystalline structure is the resonant cavity of the perovskite gain medium layer.The preparation method provided by the application does not require high-temperature treatment such as heating or thermal annealing, has a simple preparation process, low cost, can realize large-area preparation of the near-infrared perovskite laser without external resonant cavity, and by adjusting the composition of the perovskite gain material and the preparation process parameters, the emission peak of the laser can be adjusted.

Description

TECHNICAL FIELD

[0001] The present application relates to the field of perovskite lasers, in particular to a near-infrared perovskite laser without external cavity and a preparation method thereof. BACKGROUND

[0002] Near-infrared lasers have important applications in the fields of laser communication, laser radar, laser surgery and optical storage. At present, near-infrared solid-state lasers are mainly based on III-V semiconductor materials, usually prepared by methods such as metal-organic chemical vapor deposition and molecular beam epitaxy, and a high-quality resonant cavity with a complex distributed Bragg reflector (DBR) or distributed feedback (DFB) structure needs to be designed, which is complex and costly. Liquid lasers using dyes as gain medium can also emit laser 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 a near-infrared solid-state laser that can be prepared by a simple solution method.

[0003] Metal halide perovskite materials have the advantages of solution processability, tunable band gap, high color purity 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 researchers in recent years. Laser based on perovskite thin films usually needs to design a resonant cavity, increasing the complexity of the process. Laser based on perovskite microparticle or nanowire structure can utilize the structure of microparticle or nanowire itself to form a whispering gallery cavity or a Fabry-Perot (F-P) cavity to achieve gain, but it needs to synthesize nanomaterials and usually needs to transfer individual microparticles or nanowires, which is difficult to achieve large-area preparation and application. In addition, in some process methods for preparing lasers, high-temperature treatment such as heating or thermal annealing is required, which is not suitable for materials that are not resistant to high temperature.

[0004] In addition, the research of perovskite lasers mainly focuses on the visible light band, especially the green light band, and the research in the near-infrared band is still lacking. Therefore, it is of great significance to develop a near-infrared perovskite laser, especially a near-infrared perovskite laser without external cavity. SUMMARY

[0005] Therefore, the embodiments of the present application provide a near-infrared perovskite laser without external cavity and a preparation method thereof.

[0006] The embodiment of the present application provides a preparation method of an external cavity-free near-infrared perovskite laser, which comprises the following steps: dropping a perovskite precursor solution on a substrate; covering a flexible film on the substrate, so that the perovskite precursor solution is uniformly distributed between the substrate and the flexible film; and removing the flexible film after the substrate is placed and treated, to obtain a perovskite gain medium layer, wherein the flexible film is used to induce the perovskite precursor solution to grow into 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 configured by mixing and stirring a perovskite precursor material and a solvent, wherein components of the perovskite precursor material comprise 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 greater than that of A, y is in a range of 0-1, and z is an integer, and the solvent is volatile.

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

[0009] In some embodiments, the material of A' in the components of the perovskite precursor material comprises phenethylamine (PEA + ), p-fluorophenethylamine (p-F-PEA + ), m-fluorophenethylamine (m-F-PEA + ), 1-naphthylmethylamine (NMA + ) or butylamine (BA + ); the material of A in the components of the perovskite precursor material comprises cesium (Cs + ), methylamine (MA + ) or formamidinium (FA + ); the material of X in the components of the perovskite precursor material comprises Cl － , Br － or I － ; the value of y is in a range of 0-0.6, and the value of z is in a range of 3-20.

[0010] In some embodiments, the solvent comprises a mixed solution of dimethyl sulfoxide (DMSO) and N,N-dimethylformamide (DMF); and the concentration of the perovskite precursor solution is in a range of 0.02-1 M.

[0011] In some embodiments, the flexible film is used to induce the perovskite precursor solution to grow into the microcrystalline structure by controlling a volatilization rate of the solvent during the placing process of the substrate.

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

[0013] In some embodiments, the substrate comprises a flexible substrate or a rigid substrate; before the perovskite precursor solution is dropped on the substrate, the preparation method further comprises: sequentially ultrasonic cleaning the substrate with a dishwashing liquid water, deionized water, an acetone solution, and an isopropanol solution, and blowing the substrate dry with nitrogen.

[0014] In some embodiments, after the substrate is placed at room temperature, the flexible film is removed, wherein the room temperature is 15-35 degrees Celsius.

[0015] Another aspect of the embodiments of the present application also provides an external cavity-free near-infrared perovskite laser, which is prepared according to the preparation method of the above-mentioned embodiments, and comprises: a substrate; a perovskite gain medium layer disposed on the substrate, the perovskite gain medium layer having a microcrystalline structure formed thereon, the microcrystalline structure being a resonant cavity of the perovskite gain medium layer, wherein the microcrystalline structure comprises a plurality of microcrystalline units, and the shape of the microcrystalline units comprises a dendritic shape or a snowflake shape.

[0016] The external cavity-free near-infrared perovskite laser and the preparation method thereof provided by the embodiments of the present application drop the perovskite precursor solution on the substrate, and place it to dry after covering the flexible film, thereby forming the perovskite gain medium layer with the microcrystalline structure, which has at least the following beneficial effects:

[0017] (1) The preparation method of the external cavity-free near-infrared perovskite laser of the embodiments of the present application covers the flexible film on the perovskite precursor solution, which can make the perovskite precursor solution spread uniformly between the flexible film and the substrate, and the covering of the flexible film can induce the slow crystallization of the perovskite multi-sites, thereby forming the microcrystalline structure with a specific morphology, i.e., obtaining the near-infrared perovskite laser without an external resonant cavity;

[0018] (2) The preparation method of the embodiments of the present application can be carried out at room temperature without heating or heat annealing treatment, and is suitable for various rigid and flexible substrates, especially for flexible substrates that are not resistant to high temperature, and is convenient for preparing flexible external cavity-free near-infrared perovskite lasers;

[0019] (3) The preparation method of the embodiments of the present application adopts a full-solution method for preparation, which is simple in process and low in cost compared with the expensive epitaxial growth method required by conventional III-V group near-infrared lasers;

[0020] (4) The near-infrared perovskite laser of the present application does not need to design an external resonant cavity, compared with the conventional laser which needs to prepare a complex resonant cavity, the laser structure and preparation process of the present application are simpler, the cost is lower, and large-area preparation can be realized, and by adjusting the composition of the perovskite gain material, the solution concentration and the preparation process conditions, the emission peak of the laser in the 800-950 nm near-infrared waveband can be adjusted. BRIEF DESCRIPTION OF DRAWINGS

[0021] The above and other objects, features and advantages of the present application will become more apparent from the following description of embodiments of the present application taken in conjunction with the accompanying drawings, in which:

[0022] Figure 1 The structure diagram of the external-cavity-free near-infrared perovskite laser according to some embodiments of the present application is schematically shown;

[0023] Figure 2 The flowchart of the preparation method of the external-cavity-free near-infrared perovskite laser according to some embodiments of the present application is schematically shown;

[0024] Figure 3 The optical micro-morphology diagram of the perovskite gain medium layer under different perovskite precursor solution concentrations according to embodiments of the present application is schematically shown;

[0025] Figure 4 The emission spectrum diagram of the external-cavity-free near-infrared perovskite laser under different perovskite precursor solution concentrations according to embodiments of the present application is schematically shown. DETAILED DESCRIPTION

[0026] The embodiments are listed below and are described in detail with reference to the drawings, but the provided embodiments are not intended to limit the scope covered by the present application. In addition, the drawings are for illustration purposes only and are not drawn to scale. For ease of understanding, the same elements will be denoted by the same symbols in the following description.

[0027] As to the terms "comprising", "including", "having" and the like used in the present disclosure, they are open-ended terms, that is, "including but not limited to".

[0028] In addition, the directional terms mentioned in the present disclosure, such as "upper", "lower", etc., are only used to refer to the direction of the drawings and are not intended to limit the present application. Therefore, it should be understood that "upper" can be used interchangeably with "lower", and when a layer or film element 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 "directly" placed on another element, there is no intermediate element between them.

[0029] Please refer to 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 a substrate 110, and a microcrystalline structure 121 is formed on the perovskite gain medium layer 120. In this context, microcrystalline refers to micron-sized crystals. Microcrystalline structure 121 can serve as a resonant cavity for the perovskite gain medium layer 120. In other words, the perovskite gain medium layer 120 can serve as both the gain medium and the resonant cavity of the external-cavity-free near-infrared perovskite laser 100.

[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 It should be noted that, Figure 1 The region of the microcrystalline structure 121 shown in the figure is merely an example and is not intended to limit the location of the microcrystalline structure 121. In practice, 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 this microcrystalline morphology can be grown during the preparation of the perovskite gain medium layer 120.

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

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

[0034] See also Figure 2 , Figure 2A flow chart of a preparation method of the external-cavity-free near-infrared perovskite laser according to some embodiments of the present application is schematically shown. The preparation method of the external-cavity-free near-infrared perovskite laser can include operation S210 to operation 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 uniformly distributed between the substrate and the flexible film.

[0037] In operation S230, after the substrate is left for processing, the flexible film is removed, and a perovskite gain medium layer is obtained. The flexible film is used to induce the perovskite precursor solution to grow into 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] The preparation method of the external-cavity-free near-infrared perovskite laser according to the embodiments of the present application can make the perovskite precursor solution uniformly spread between the flexible film and the substrate by covering the flexible film on the perovskite precursor solution. The coverage of the flexible film can induce the perovskite multi-site slow crystallization, so as to form a microcrystalline structure with a specific morphology, i.e. to obtain a near-infrared perovskite laser without an external resonant cavity. The preparation method of the embodiments of the present application can be carried out at room temperature without heating or heat annealing treatment, and is suitable for various rigid and flexible substrates, especially for flexible substrates which are not resistant to high temperature, and is convenient for preparing a flexible external-cavity-free near-infrared perovskite laser. In addition, the preparation method of the embodiments of the present application is prepared by a full solution method, which is simple and low in cost compared with the expensive epitaxial growth method of conventional III-V group near-infrared lasers.

[0039] In some embodiments, the preparation method shown in Figure 2 can be used to prepare the external-cavity-free near-infrared perovskite laser 100 shown in Figure 1 . The preparation method of the external-cavity-free near-infrared perovskite laser 100 will be further described in combination with Figure 1 and Figure 2 .

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

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

[0042] In some embodiments, the perovskite precursor solution can be configured by mixing and stirring a perovskite precursor material and a solvent. Perovskite generally refers to a class of compounds with a general formula of ABX3, where A represents a monovalent cation, B represents a divalent metal cation, and X represents a halide anion. In the embodiments of the present application, the excitation wavelength of the external-cavity-free near-infrared perovskite laser 100 can be adjusted by changing the components of the perovskite precursor material, i.e., by changing the composition and proportion of A, B, and X in the conventional ABX3 structure to achieve different emission wavelengths.

[0043] Specifically, the components of the perovskite precursor material in the present embodiment can 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 that of A, and y has a value in the range of 0-1. The combination of A' and A is equivalent to A in the conventional 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 that can effectively hinder the entry of oxygen and water molecules and prevent the discharge of decomposition products, thereby improving the long-term stability of the perovskite thin film. At the same time, the exciton binding energy of the quasi-two-dimensional perovskite is large, which is beneficial to improve the luminescent performance of the perovskite thin film. Sn (tin) corresponds to B in the conventional ABX3 structure. Compared with Pb as the perovskite material at B site, the introduction of Sn can narrow the band gap of the metal halide perovskite material, red-shift the luminescent peak, and realize luminescence in the near-infrared region. X is a halide 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 in A'2A + Cs + MA + , FAone or more of phenylethylamine (PEA + ), p-fluorophenylethylamine (p-F-PEA + ), m-fluorophenylethylamine (m-F-PEA + ), 1-naphthylmethylamine (NMA + ), butylamine (BA + ), or a combination thereof. X can be one or more of Cl － , Br － , I － . The value of y can be further set to a range of 0-0.6, where y can be equal to 0 or 0.6. The value of z can be further set to a range of 3-20, where z can be equal to 3 or 20. By changing the material of A' y A 1-y SnX3or A'2A z-1 Sn z X 3z+1 , the material of A, the material of X, and the values of y and z, the band gap of the perovskite can be controlled, thereby achieving the control of the excitation wavelength of the external-cavity-free near-infrared perovskite laser 100.

[0045] In this embodiment, the perovskite precursor solution further contains a volatile solvent. During the volatilization of the solvent, the perovskite can crystallize at multiple sites, and different volatilization rates can obtain crystals with different morphologies. By changing the ratio of the solvent to the perovskite precursor material or changing the amount of the solvent alone, perovskite precursor solutions with different concentrations can be prepared. By adjusting the concentration of the perovskite precursor, the crystalline morphology of the perovskite can be controlled, thereby enabling the adjustment of the lasing peak. That is, the excitation wavelength of the external-cavity-free near-infrared perovskite laser 100 is related to the material of A', A, and X in the components of the perovskite precursor material, the values of y and z, and the concentration of the perovskite precursor solution.

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

[0047] In operation S220, a flexible film is covered on the substrate 110, so that the perovskite precursor solution is uniformly 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) film, a polyethylene naphthalate (PEN) film, a styrene-ethylene-butylene-styrene block copolymer (SEBS) film, or an ethyl cellulose (EC) film. Taking a PDMS film with a thickness of 0.02-1 mm and a smooth surface as an example, the PDMS film has good flexibility and stretchability, and can tightly adhere to the substrate 110 and the perovskite precursor solution after being covered on the substrate 110, so that the perovskite precursor solution is uniformly distributed between the substrate 110 and the PDMS film. Then, operation S230 is performed.

[0049] In operation S230, after the substrate 110 is placed and processed, the flexible film is removed, and the perovskite gain medium layer 120 is obtained.

[0050] Specifically, the substrate 110 covered with the film can be placed at room temperature of 15-35 degrees Celsius for 8-24 hours. During the standing process, the flexible film can slow down the evaporation rate of the solvent in the perovskite precursor solution, thereby inducing slow crystallization of the perovskite multi-site. Then, the flexible film is removed, and the perovskite gain medium layer 120 is obtained, and the microcrystal units 121a and 121b on the microcrystal structure 121 are formed. It can be seen that, in the present embodiment, no heating or thermal annealing process is needed, and no external solvent atmosphere is needed. By only covering the flexible film and standing at room temperature, the perovskite gain medium layer 120 is obtained, and the preparation of the external-cavity-free near-infrared perovskite laser 100 is completed.

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

[0052] Embodiments

[0053] (1) Preparation of perovskite precursor solution

[0054] Preparation of three different concentrations of PEA x FA 1-xSnI3 perovskite precursor solution. PEAI, FAI, SnI2, and SnF2 were weighed according to a molar ratio of 0.15:0.85:1:0.075, respectively, 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. The solution concentrations were 0.4 M, 0.2 M, and 0.1 M, respectively, by controlling the amount of the mixed solution of DMF and DMSO. Magnetic stirring was performed for 12 hours to obtain the perovskite precursor solution.

[0055] (2) Preparation of perovskite laser

[0056] First, the substrate was cleaned. The quartz substrate was ultrasonically cleaned with a detergent water, deionized water, acetone, and isopropanol solution, respectively, for 20 minutes, and then dried with nitrogen.

[0057] Then, the substrate was moved into a nitrogen glove box, 10 μL of the perovskite precursor solution was dropped onto the substrate, and then a PDMS film with a flat surface was covered on the substrate to evenly spread the perovskite precursor solution between the quartz substrate and the PDMS, forming 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 surface of the substrate, completing the preparation of the perovskite laser.

[0058] Please refer to Figure 3 and Figure 4 , Figure 3 Figures schematically show the optical micro-morphology of the perovskite gain medium layer according to the embodiments of the present application under different perovskite precursor solution concentrations (0.4 M, 0.2 M, and 0.1 M), Figure 4 Figures schematically show the emission spectrum of the external-cavity-free near-infrared perovskite laser according to the embodiments of the present application under different perovskite precursor solution concentrations (0.4 M, 0.2 M, and 0.1 M).

[0059] As shown in Figure 3 , the optical micro-morphology of the perovskite gain medium layer according to the embodiments of the present application presents a large number of dendritic 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] As shown in Figure 4As shown, the abscissa represents wavelength (unit: nm), and the ordinate represents normalized intensity (unit: a.u.). It can be seen that, with the decrease of the concentration of the perovskite precursor solution, the emission peak position of the external cavity-free near-infrared perovskite laser provided by the embodiment of the present application is blue-shifted, i.e., the maximum emission peak wavelength moves to a short wave. It is illustrated that, without changing the perovskite component, the emission peak position of the laser can be adjusted by simply regulating the concentration of the perovskite precursor solution.

[0061] So far, the external cavity-free near-infrared perovskite laser and the preparation method thereof are introduced. According to the embodiments, the preparation method of the external cavity-free near-infrared perovskite laser provided by the present application can make the perovskite precursor solution spread uniformly between the flexible film and the substrate by covering the flexible film on the perovskite precursor solution, and the covering of the flexible film can induce the slow crystallization of the perovskite multi-site, so as to form a microcrystalline structure with a specific morphology, i.e., the external cavity-free near-infrared perovskite laser is obtained; the preparation method of the embodiment of the present application can be carried out at room temperature without heating or heat annealing treatment, and is suitable for various rigid and flexible substrates, especially suitable for flexible substrates that are not resistant to high temperature, and is convenient for preparing flexible external cavity-free near-infrared perovskite lasers; the preparation method of the embodiment of the present application is prepared by using the all-solution method, and compared with the growth method of the conventional III-V group near-infrared laser which needs to use expensive epitaxial process, the solution method process is simple and low in cost; the laser of the present application does not need to design an external resonant cavity, and compared with the conventional laser which needs to prepare a complex resonant cavity, the laser structure and preparation process of the present application are simpler, lower in cost, and can realize large-area preparation, and by regulating the component of the perovskite gain material, the solution concentration and the preparation process conditions, the emission peak of the laser can be adjusted in the 800-950 nm near-infrared waveband.

[0062] In conclusion, although the present application has been disclosed as above by embodiments, it is not intended to limit the present application. Those skilled in the art of the present application can make various modifications and decorations without departing from the spirit and scope of the present application. Therefore, the protection scope of the present application shall be subject to the appended claims.

Claims

1. A method for fabricating an external cavity-free near-infrared perovskite laser, characterized in that, The preparation method comprises the following steps: dropping a perovskite precursor solution on a substrate; covering a flexible film on the substrate, so that the perovskite precursor solution is uniformly distributed between the substrate and the flexible film; after static treatment of the substrate, removing the flexible film to obtain a perovskite gain medium layer, wherein the flexible film is used to induce the perovskite precursor solution to grow into 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.

2. The production method according to claim 1, characterized by, The perovskite precursor solution is configured by mixing and stirring a perovskite precursor material and a solvent, wherein the components of the perovskite precursor material comprise 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 halide anion, the size of A' is larger than A, y is in the range of 0 to 1, and z is an integer, the solvent has volatility.

3. The preparation method according to claim 2, characterized in that The excitation wavelength of the external-cavity-free near-infrared perovskite laser is related to the components of the perovskite precursor material, the values of A', A, X and y, z, and the concentration of the perovskite precursor solution.

4. The preparation method according to claim 2, characterized in that The material of A' in the components of the perovskite precursor material includes phenethylamine (PEA + ), p-fluorophenethylamine (p-F-PEA + ), m-fluorophenethylamine (m-F-PEA + ), 1-naphthylmethylamine (NMA + ), or butylamine (BA + ). The material of A in the components of the perovskite precursor material includes cesium (Cs + ), methylamine (MA + ), or formamidinium (FA + ); The material of X in the components of the perovskite precursor material includes CI － , Br － , or I － ; The value of y ranges from 0 to 0.6, and the value of z ranges from 3 to 20.

5. The preparation method according to claim 2, characterized in that The solvent comprises a mixed solution of dimethyl sulfoxide (DMSO) and N,N-dimethylformamide (DMF); and the concentration of the perovskite precursor solution ranges from 0.02 M to 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 treatment of the substrate, thereby inducing the perovskite precursor solution to grow into the microcrystalline structure.

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

8. The method of claim 1, wherein, The substrate comprises a flexible substrate or a rigid substrate. Before the step of dropping the perovskite precursor solution on the substrate, the preparation method further comprises the following steps: ultrasonically cleaning the substrate with a dishwashing liquid, deionized water, acetone, and isopropyl alcohol solution, and blowing the substrate dry with nitrogen.

9. The method of claim 1, wherein, After the static treatment of the substrate, the flexible film is removed, wherein the substrate is placed at room temperature for static treatment, and the flexible film is removed after the static treatment, and the room temperature ranges from 15 to 35 degrees Celsius. The preparation method comprises the following steps:

10. A near-infrared extracavity perovskite laser prepared by the method of any one of claims 1 to 9, characterized in that a substrate; a perovskite gain medium layer disposed on the substrate, wherein 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 comprises a plurality of microcrystalline units, and the shape of the microcrystalline unit comprises a dendritic shape or a snowflake shape. ​

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