CN111909686A

CN111909686A - Mixed multi-cation perovskite material film with optical gain characteristic and preparation method and application thereof

Info

Publication number: CN111909686A
Application number: CN202010578603.5A
Authority: CN
Inventors: 张青; 李美丽; 尚秋宇
Original assignee: Peking University
Current assignee: Peking University
Priority date: 2020-06-23
Filing date: 2020-06-23
Publication date: 2020-11-10
Anticipated expiration: 2040-06-23
Also published as: CN111909686B

Abstract

The invention discloses a mixed multi-cation perovskite material film with optical gain characteristic, and a preparation method and application thereof, wherein the general chemical structure formula of the mixed multi-cation perovskite material film is [ (A)_0.87BxCy)PbX₃]_b[A’₂PbX₄]_c；A_0.87In BxCy, x + y is 0.13, 0.87 is the mass ratio of a to the total mass of a + B + C, x is the mass ratio of B to the total mass of a + B + C, and y is the mass ratio of C to the total mass of a + B + C; the thickness of the mixed multi-cation perovskite material film is 20 nm-200 nm; the gain coefficient is 800-3000cm^‑1(ii) a The light-emitting wavelength range is 510-530 nm; roughness of 0.5nm-5 nm. The invention improves the optical and thermal stability of the perovskite material and the gain characteristic of the thin film.

Description

Mixed multi-cation perovskite material film with optical gain characteristic and preparation method and application thereof

Technical Field

The invention belongs to the field of perovskite materials, and particularly relates to a mixed multi-cation perovskite material film with optical gain characteristics, and a preparation method and application thereof.

Background

As a new semiconductor photoelectric material, the metal halide perovskite has excellent photoelectric properties such as large absorption coefficient, low defect state density, high fluorescence quantum yield, tunable light-emitting band gap and the like, so that the metal halide perovskite has wide application prospect in the field of photoelectronic devices. The general chemical formula of the perovskite material can be represented as ABX₃The B ion and the X ion can form a regular octahedral structure, wherein A is Cs⁺、CH₃NH₃ ⁺(MA)、HC(NH₂)⁺(FA) etc., the B ion is Pb²⁺、Sn²⁺Isocation, X ion is I^-、Br^-、Cl^-And (4) plasma. Meanwhile, the ionic radius of A, B and X determines the stability of the perovskite crystal structure, and when the lattice tolerance factor is 0.9-1, the perovskite structure has good symmetry and tends to be a stable cubic perovskite crystal structure. Thus, the components of the perovskite material may be partially replaced to form a variety of stable structures. When ions are partially substituted, the ions do not change structurally, but the differences in the radii and valence states of the ions of different elements tend to cause changes in the macroscopic physical properties of the perovskite material. Due to the flexibility of the perovskite crystal structure, the shape can be freely adjusted in the synthesis process, and the unique luminescence property can be realized. Therefore, by virtue of its excellent characteristics, perovskite materials have attracted great attention from researchers in the fields of light emitting diodes and lasers.

Laser is a process in which a gain medium that provides feedback in a cavity is excited to form population inversion to generate optical radiation. The process of realizing optical gain by stimulated radiation of the semiconductor is as follows: a photon is incident on the semiconductor material and undergoes an electronic transition, producing a stimulated emission photon identical to itself. Compared with the traditional semiconductor material, the perovskite material is used as a gain medium, has relatively high refractive index and can form larger reflection contrast with the environment medium; thus, the laser can be used as a resonant cavity of the laser and provides possibility for the size of the laser to break through the traditional diffraction limit. When light is incident on the gain medium, the gain of the light is related to the exponential growth trend of the emitted light intensity along with the increase of the distance; optical loss refers to the condition of photon scattering, nonradiative recombination, edge scattering, etc. when light is transmitted in a semiconductor medium. Therefore, to achieve laser output, it is necessary to satisfy the requirement that the gain be greater than the loss, i.e., that there be a positive net gain. And establishing a net gain model formula according to the condition of gain loss, wherein the formula is as follows:

wherein I is the output intensity, A is a constant, g is the net gain coefficient, and Lg is the pump fringe length; the net gain coefficient g value can be obtained by various strip length measuring methods and the combination of the formula fitting. At present, researches on Amplified Spontaneous Emission (ASE) photons of organic-inorganic hybrid perovskites and all-inorganic perovskites are more, and compared with polycrystalline thin films prepared by a one-step solution spin coating method, the gain coefficient measured in various perovskite nanocrystalline thin films is higher. For example in MAPbBr₃The highest gain coefficient measured in the nanocrystalline thin film was 520cm^-1，FAPbI₃The nano-crystalline film is 604cm^-1，CsPbBr₃The nanocrystalline thin film is 980cm^-1. However, due to the high absorption coefficient of perovskite materials, the theoretical optical gain of perovskite has been reported to be as high as 3200. + -. 830cm^-1Comparable to single crystal gallium arsenide (GaAs). In addition, this gain proved to last approximately 200ps, with a threshold value close to 16 μ J cm^-2. The ultimate goal of the research on net mode gain is to integrate it into an optical amplification device to achieve an optically or electrically pumped laser.

Although the research on the optically pumped perovskite laser is sufficient at present, the practical application of the perovskite optically pumped laser is hindered due to the poor stability and light resistance of the material, the large non-radiative recombination caused by defects, the low intrinsic gain and the like. Furthermore, electrical pumping is a commercially common excitation approach compared to optically pumped lasers, however, implementing electrically pumped lasers still presents certain challenges at present. On the one hand, the current density required to reach the threshold of the carrier density of the laser emission is high. On the other hand, the thermal effect of the electrically pumped device must be reduced, since a higher charge injection density may damage the gain medium. Therefore, the preparation of the perovskite thin film material with high stability and high gain characteristic has important significance for promoting the practical application of the perovskite laser.

Disclosure of Invention

The present invention aims to provide a mixed polycationic perovskite material thin film having optical gain characteristics. The invention improves the optical and thermal stability of the perovskite material and the gain characteristic of the thin film.

In order to achieve the purpose, the technical scheme of the invention is as follows:

a mixed multi-cation perovskite material film with optical gain characteristics, wherein the general chemical structural formula of the mixed multi-cation perovskite material film is [ (A)_0.87BxCy)PbX₃]_b[A’₂PbX₄]_c；

Wherein A is selected from one or more of methylamine cation, formamidine cation and inorganic cesium cation;

b is selected from one or more of methylamine cation, formamidine cation and inorganic cesium cation;

c is selected from one or more of methylamine cation, formamidine cation and inorganic cesium cation;

a' is one or more of a naphthylmethylamine cation, a butylamine cation and a phenylethylamine cation;

x is a halide anion;

b, c is 1 (0-0.8);

A_0.87in BxCy, x + y is 0.13, 0.87 is the mass ratio of a to the total mass of a + B + C, x is the mass ratio of B to the total mass of a + B + C, and y is the mass ratio of C to the total mass of a + B + C;

the thickness of the mixed multi-cation perovskite material film is 30 nm-300 nm; increaseThe coefficient of benefit is 800-3000cm^-1(ii) a The light-emitting wavelength range is 510-530 nm; the roughness is 0.5nm-5 nm.

Preferably, the b: c is 1 (0.2-0.8).

Another object of the present invention is to provide a method for preparing a mixed polycation material having optical gain characteristics, comprising the steps of:

1) mixing AX, BX, CX and PbX₂Dissolving the raw materials in a precursor solvent according to the molar ratio of 2.2: m: n:1, heating, stirring and filtering to obtain the three-dimensional (3D) perovskite (A)_0.87B_0.13)PbX₃Or (A)_0.87BxCy)PbX₃The precursor solution of (1); wherein the molar concentration of the 3D perovskite is 0.5 mol.L^-1；

2) A' X and PbX are mixed₂Dissolved in a precursor solvent according to the molar ratio of 2:1 to form two-dimensional (2D) perovskite A'₂PbX₄The precursor solution of (1); wherein the molar concentration ratio of 3D perovskite to A 'cation is a, two-dimensional (2D) perovskite A'₂PbX₄In a molar concentration range of 0 to 0.5 mol.L^-1；

3) Isovolumetrically mixing the precursor solutions of the two perovskites prepared in the steps 1) and 2) to obtain a multi-cation mixed perovskite precursor solution;

4) taking a proper amount of the precursor solution obtained in the step 3), dripping the precursor solution on a substrate, standing on the substrate after the solution is spread, and spin-coating to form a film and removing the precursor solvent to obtain the mixed polycation perovskite film;

wherein: A. b and C are one or more of short-chain organic cations; A. three or two of B and C may be the same or three may be different; specifically, A, B or C is selected from one or more of methylamine cation, formamidine cation and cesium cation.

A' is an aliphatic alkylamine cation and/or an aromatic alkylamine cation; the aliphatic alkylamine cation is butylamine cation; the aromatic alkylamine cation is one or two of naphthalene methylamine cation and phenethylamine cation.

X is a halide anion, preferably a bromide anion.

(A_0.87BxCy)PbX₃X and y in the structural formula refer to the percentage of B and C in the total mass of ABC, and x + y is 0.13.

The molar concentration ratio a of the 3D perovskite to the A' cation is in the range of 0-1, wherein the molar concentration of the 2D perovskite is in the range of 0-0.5mol L^-1；

According to a preferred embodiment of the invention, AX is selected from one of methylamine bromide, formamidine bromide, cesium bromide; BX is selected from one of methylamine bromide, formamidine bromide and cesium bromide; CX is selected from one of methylamine bromide, formamidine bromide and cesium bromide.

According to a preferred embodiment of the invention, a' X is selected from one or more of naphthylmethylamine bromide, butylamine bromide, phenylethylamine bromide.

According to a preferred embodiment of the invention, PbX₂Is PbBr₂。

Specifically, the polycations in the multi-cation mixed perovskite precursor solution in step 3) may be any one of the following combinations:

butylamine cation, methylamine cation, formamidine cation and Pb²⁺A cation; phenylethylamine cation, methylamine cation, formamidine cation and Pb²⁺A cation; naphthylmethylamine cation, methylamine cation, formamidine cation and Pb²⁺A cation; butylamine cation, methylamine cation, formamidine cation, cesium cation and Pb²⁺A cation; phenethylamine cation, methylamine cation, formamidine cation, cesium cation and Pb²⁺A cation; naphthylmethylamine cation, methylamine cation, formamidine cation, cesium cation and Pb²⁺A cation.

The precursor solution in step 3) may be a combination of: butylamine cations, methylamine cations, formamidine cations, and phenethylamine cations; butylamine cations, methylamine cations, formamidine cations, naphthylamine cations; phenylethylamine cation, methylamine cation, formamidine cation, naphthylmethylamine cation; butylamine cations, methylamine cations, cesium cations, and phenethylamine cations; butylamine cation, methylamine cation, cesiumCations, naphthylamine cations; phenethylamine cations, methylamine cations, cesium cations, naphthylmethylamine cations; butylamine cations, cesium cations, formamidine cations, and phenethylamine cations; butylamine cations, cesium cations, formamidine cations, naphthylamine cations; and phenethylamine cation, cesium cation, formamidine cation, naphthylmethylamine cation and Pb²⁺Cation and X^-And (3) any group of anion mixed solutions.

The solvents of the precursor solutions in the step 1) and the step 2) are the same or different; the solvent is one or more of N-N Dimethylformamide (DMF), dimethyl sulfoxide (DMSO) or gamma-butyrolactone.

The substrate used for forming the film by the multi-cation mixed precursor solution is a silicon wafer, glass, silicon dioxide or sapphire.

AX, BX, CX, and PbX of the step 1)₂M and n, m plus n being equal to 0.01.

The heating and stirring of the step 1) are carried out, the heating temperature range is 30-50 ℃, and the stirring time range is 15-24 h.

And 4) forming a film by spin coating, wherein the amount of the precursor solution is 20-50 mu L.

And 4) forming the film by spin coating, wherein the retention time of the precursor solution on the substrate is 0-20 min.

The spin coating of the step 4) is used for forming the film, and the rotating speed is 1000-6000 r.min^-1And the time is 30-200 s.

The thickness of the multi-cation mixed perovskite thin film prepared by the invention is 30 nm-300 nm; the gain coefficient reaches 800-3000cm^-1。

The multi-cation mixed perovskite thin film prepared by the invention has the light-emitting wavelength range of 510-530 nm.

Compared with the prior art, the mixed cation perovskite material prepared by the invention is subjected to solution spin coating to form a film, and the prepared film has high crystal quality, smooth and flat appearance and no pin hole; on the other hand, the long-chain cations coated on the surface of the inorganic layer further improve the stability of the 3D mixed cation perovskite thin film.

Specifically, compared with the prior art, the invention has the beneficial effects that:

(1) a series of thin films with different thicknesses are obtained by adjusting the concentration of the mixed multi-cation perovskite precursor solution, the detention time of the solution on the substrate and the rotating speed during film spinning, and a theoretical basis is provided for the research on the gain property of the multi-cation mixed perovskite thin film through the characterization of absorption, emission and time resolution spectrums and an X-ray diffraction (XRD) spectrum.

(2) From the above characterization results, it was found that after long-chain organic cations are introduced into the 3D mixed cation perovskite, the stability of the optical gain layer is improved by preventing water in the air from permeating due to the protective effect of the long-chain amine, and as shown in fig. 2, the intensity of ASE is almost not attenuated after as long as 10 hours under the irradiation of the continuous pulse laser.

(3) By regulating the thickness of the film, the net gain coefficient of the multi-cation mixed perovskite film as a gain medium is changed from small to large, namely the gain coefficient of ASE depends on the thickness of the film and the state of the surface of the film, such as the roughness.

(4) Through regulation and control of cation species and components, compared with pure 3D mixed cation perovskite, the crystal obtained by further doping long-chain organic cations has higher quality. Mainly manifested by narrow absorption band tails, strong fluorescence emission intensity and slow hot carrier cooling. Secondly, the growth of 3D mixed cation perovskite is blocked by long-chain amine, so that the grain size is reduced and the integral flatness of the film is improved; due to the difference of the dielectric environments of the long-chain amine and the inorganic layer, excitons are quickly accumulated on isolated nanoparticles, the number of the particles is reversed, the light emitting mechanisms of the isolated nanoparticles are different, and the multi-cation mixed perovskite thin film has a high gain coefficient. Wherein the gain coefficient of the mixed cation film material with high gain characteristic is up to 800-3000cm^-1The gain factor is improved by nearly an order of magnitude compared to 3D perovskites and 2D layered perovskites, as shown in fig. 3 and 4.

(5) The characteristics of the room temperature gain property and the stability of the optical gain layer of the mixed cation perovskite thin film material provide powerful support for further promoting the practical application of the laser in the future.

Drawings

FIG. 1 is a schematic structural diagram of a multi-cation mixed perovskite according to example two of the present invention;

FIG. 2 is stability data for a multi-cation mixed perovskite thin film prepared in example five of the present invention;

FIG. 3 is an ASE spectrum of a mixed cation perovskite thin film prepared according to example eleven of the present invention;

FIG. 4 is data of net gain coefficient for mixed cation perovskite thin films prepared in example eleven of the present invention;

FIG. 5 is an atomic force microscope photograph of a complex cationic perovskite thin film prepared according to the twelfth embodiment of the invention.

Detailed Description

The following will explain the preparation method of the multi-cation mixed perovskite material provided by the invention in detail with reference to the accompanying drawings and specific examples.

A method for preparing a mixed polycation material with optical gain characteristics, which comprises the following steps:

1) mixing AX, BX, CX and PbX₂Dissolving the raw materials in a precursor solvent according to the molar ratio of 2.2: m: n:1, heating, stirring and filtering to obtain the three-dimensional (3D) perovskite (A)_0.87B_0.13)PbX₃Or (A)_0.87BxCy)PbX₃The precursor solution of (1); wherein the molar concentration of the 3D perovskite is 0.5mol L^-1；

2) A' X and PbX are mixed₂Dissolved in a precursor solvent according to the molar ratio of 2:1 to form two-dimensional (2D) perovskite A'₂PbX₄The precursor solution of (1);

3) isometric mixing the precursor solutions of the two perovskites prepared in the steps 1) and 2), wherein the molar concentration ratio of the 3D perovskites to the A' cations is a, so as to obtain a multi-cation mixed perovskite precursor solution;

4) taking a proper amount of the precursor solution obtained in the step 3) by using a 100-microliter liquid-transferring gun, dripping the precursor solution on a substrate, standing on the substrate after the solution is spread, and spin-coating to form a film to remove the precursor solvent to obtain a mixed polycation perovskite thin film;

wherein the structural general formula of the mixed multi-cation perovskite material is [ (A)_0.87BxCy)PbX₃]_b[A’₂PbX₄]_cA, B and C are short-chain organic cations, A' is an aliphatic or aromatic alkylamine cation, and X is a halogen anion (Br)^-) (ii) a b means (A)_0.87BxCy)PbX₃C is A 'in the whole component'₂PbX₄The ratio of b to c in the overall composition determines the properties of the mixed cation perovskite material, where the ratio of b to c may range from 0 to 2, with an optimal ratio ranging from 0.2 to 0.8, as shown in fig. 4.

The molar concentration ratio a of the 3D perovskite to the A' cation is in the range of 0-1, and the molar concentration is in the range of 0-0.5mol L^-1The optimum concentration range is 0-0.3mol L^-1。

The AX, BX and CX include methylamine bromide (MABr), formamidine bromide (FABr) and cesium bromide (CsBr).

The A' X comprises naphthylmethylamine bromine (NMABr), butylamine bromine (BABr) and phenethylamine bromine (PEABr).

The PbX₂Is PbBr₂。

The structure of the 3D mixed cation perovskite material comprises: (MA)_0.87FAxCsy)PbX₃、 (FA_0.87MAxCsy)PbX₃、(Cs_0.87MAxFAy)PbX₃、(MA_0.87FA_0.13)PbX₃、(MA_0.87Cs_0.13)PbX₃、 (FA_0.87MA_0.13)PbX₃、(FA_0.87Cs_0.13)PbX₃、(Cs_0.87FA_0.13)PbX₃、(Cs_0.87MA_0.13)PbX₃。

The 2D perovskite material comprises: butylamine lead Bromoperovskite (BA)₂PbBr₄Phenylethylamine lead bromine Perovskite (PEA)₂PbBr₄Naphthalene methylamine lead bromoperovskite (NMA)₂PbBr₄。

The precursor solution of the multi-cation mixed perovskite material comprises: (MA)_0.87FAxCsy)PbX₃And (BA)₂PbBr₄，(MA_0.87FAxCsy)PbX₃And (PEA)₂PbBr₄，(MA_0.87FAxCsy)PbX₃And (NMA)₂PbBr₄，(FA_0.87MAxCsy)PbX₃And (BA)₂PbBr₄，(FA_0.87MAxCsy)PbX₃And (PEA)₂PbBr₄，(FA_0.87MAxCsy)PbX₃And (NMA)₂PbBr₄，(Cs_0.87MAxFAy)PbX₃And (BA)₂PbBr₄， (Cs_0.87MAxFAy)PbX₃And (PEA)₂PbBr₄，(Cs_0.87MAxFAy)PbX₃And (NMA)₂PbBr₄Wherein the gain coefficients measured after spin coating of the precursor solution of any group of the multi-cation mixed perovskite materials are larger than or equal to 800cm^-1。

The precursor solution of the multi-cation mixed perovskite material can further comprise: (MA)_0.87FA_0.13)PbX₃And (BA)₂PbBr₄，(MA_0.87FA_0.13)PbX₃And (PEA)₂PbBr₄，(MA_0.87FA_0.13)PbX₃And (NMA)₂PbBr₄， (MA_0.87Cs_0.13)PbX₃And (BA)₂PbBr₄，(MA_0.87Cs_0.13)PbX₃And (PEA)₂PbBr₄， (MA_0.87Cs_0.13)PbX₃And (NMA)₂PbBr₄，(FA_0.87MA_0.13)PbX₃And (BA)₂PbBr₄， (FA_0.87MA_0.13)PbX₃And (PEA)₂PbBr₄，(FA_0.87MA_0.13)PbX₃And (NMA)₂PbBr₄， (FA_0.87Cs_0.13)PbX₃And (BA)₂PbBr₄，(FA_0.87Cs_0.13)PbX₃And (PEA)₂PbBr₄，(FA_0.87Cs_0.13)PbX₃And (NMA)₂PbBr₄，(Cs_0.87FA_0.13)PbX₃And (BA)₂PbBr₄，(Cs_0.87FA_0.13)PbX₃And (PEA)₂PbBr₄， (Cs_0.87FA_0.13)PbX₃And (NMA)₂PbBr₄，(Cs_0.87MA_0.13)PbX₃And (BA)₂PbBr₄， (Cs_0.87MA_0.13)PbX₃And (PEA)₂PbBr₄，(Cs_0.87MA_0.13)PbX₃And (NMA)₂PbBr₄Wherein the gain coefficients measured after spin coating of the precursor solution of any group of the multi-cation mixed perovskite materials are larger than or equal to 600cm^-1。

The multi-cation mixed perovskite material has the luminescent wavelength range of 510-530nm and the variation range of the gain coefficient of 800-3000cm^-1And when the gain coefficient is larger than or equal to 800cm^-1It is shown that this material has high gain characteristics.

The concentration ratio a of the 3D mixed cation perovskite to the long-chain cation (A') in the precursor solution of the multi-cation mixed perovskite material which can be processed by the solution is 0, 0.2, 0.4, 0.8, 1.2, 1.6 and 2, wherein the used solvent is one or two of N-N Dimethylformamide (DMF), dimethyl sulfoxide (DMSO) and gamma-butyrolactone.

The substrate used for the film formation of the multi-cation mixed perovskite material can be glass, silicon wafer, quartz or sapphire.

The AX, BX, CX and PbX₂M and n, m plus n being equal to 0.01.

The heating and stirring are carried out, the heating temperature range is 30-60 ℃, and the stirring time range is 15-24 h.

The multi-cation mixed perovskite material is subjected to spin coating in an inert environment to form a film, wherein the rotating speed is 1000-6000 r.min^-1And the time is 30-200 s.

By regulating the concentration of the multi-cation mixed perovskite material, the residence time (0-20 min) of the precursor solution on the substrate and the rotating speed, the thickness range of the film is increased from 30nm to 300nm, and the roughness range is changed from 0.5nm to 5 nm.

In the technical scheme, the gain coefficient of the multi-cation mixed perovskite material as the laser gain material is related to the film thickness and the excitation power of the laser gain material, wherein the beneficial film thickness is 60-100nm, and the excitation power is 2-100P_th(P_th: a threshold).

Example one

A method of making a mixed polycationic material having optical gain characteristics comprising the steps of:

1) MABr, FABr, CsBr and PbBr₂Dissolving in anhydrous dimethyl sulfoxide (DMSO) at a molar ratio of 2.2:0.05:0.05:1, heating at 30 deg.C and stirring for 20 hr to form [ MA_0.87(FACs)_0.13]PbBr₃The precursor solution of the 3D mixed cation perovskite has the concentration of 0.2mol L^-1；

2) BABr and PbBr₂Dissolving in anhydrous dimethyl sulfoxide (DMSO) at a ratio of 2:1 to form 2D perovskite (BA)₂PbBr₄The precursor solution of (2) has a concentration of 0.1mol L^-1；

3) Mixing the precursor solutions of the two perovskites in equal volume to obtain the multi-cation mixed perovskite material [ MA [ ]_0.87(FACs)_0.13]PbBr₃]_0.5[(BA)₂PbBr₄]_0.1The precursor solution of (1);

4) dripping 100 μ L of the above perovskite precursor solution on a glass substrate with a liquid-transferring gun, spreading the solution, staying on the substrate for 3min, and then standing for 1000r min^-1The mixed cation perovskite thin film is obtained by removing the precursor solvent at the rotating speed of 60s, the thickness is 60nm, the roughness is 1.5nm, and the position of an emission spectrum is 519 nm.

Wherein, when the excitation power is 50P_thThe gain coefficient is 800cm^-1And has high gain characteristic.

Example two

1) FABr, MABr, CsBr and PbBr₂Dissolving in anhydrous dimethyl sulfoxide (DMSO) at a molar ratio of 2.2:0.05:0.05:1, heating and stirring at 30 deg.C for 20 hr to form [ FA%_0.87(MACs)_0.13]PbBr₃The precursor solution of the 3D mixed cation perovskite has the concentration of 0.5mol L^-1；

2) NMABr and PbBr₂Dissolving in anhydrous dimethyl sulfoxide (DMSO) at a ratio of 2:1 to form 2D perovskite (NMA)₂PbBr₄The precursor solution of (2) has a concentration of 0.2mol L^-1；

3) Mixing the precursor solutions of the two perovskites in equal volume to obtain the multi-cation mixed perovskite material [ FA [ ]_0.87(MACs)_0.13]PbBr₃]_0.5[(NMA)₂PbBr₄]_0.2The precursor solution of (1);

4) dripping 60 μ L of the above perovskite precursor solution on a glass substrate with a liquid-transferring gun, spreading the solution, staying on the substrate for 10min, and then allowing the solution to stand for 3000r min^-1The rotating speed of the precursor is rotated for 60s, and the precursor solvent is removed to obtain the mixed cation perovskite thin film, wherein the structural schematic diagram of the mixed cation perovskite thin film is shown in the attached figure 1. FA⁺、MA⁺、Cs⁺Is filled in the gap of the inorganic lead halide regular octahedron, and the long-chain organic cations are coated on the surface of the 3D perovskite; the thickness is 100nm, the roughness is 0.5nm, and the position of an emission spectrum is 529 nm.

Wherein, when the excitation power is 80P_thThe gain coefficient is 900cm^-1And has high gain characteristic.

EXAMPLE III

1) CsBr, MABr, FABr and PbBr₂Dissolving in anhydrous N-N Dimethylformamide (DMF) at a molar ratio of 2.2:0.01:0.09:1, and stirring at 35 deg.C for 20 hr to form [ Cs_0.87(MAFA)_0.13]PbBr₃The precursor solution of the 3D mixed cation perovskite has the concentration of 0.5mol L^-1；

2) PEABr and PbBr₂Dissolving in anhydrous N-N Dimethylformamide (DMF) at a ratio of 2:1 to form 2D Perovskite (PEA)₂PbBr₄The precursor solution of (2) has a concentration of 0.2mol L^-1；

3) Mixing the precursor solutions of the two perovskites in equal volume to obtain the multi-cation mixed perovskite material [ [ Cs ]_0.87(MAFA)_0.13]PbBr₃]_0.5[(PEA)₂PbBr₄]_0.2The precursor solution of (1);

4) dripping 50 μ L of the above perovskite precursor solution on a glass substrate with a liquid-transferring gun, spreading the solution, staying on the substrate for 10min, and then performing 4000r min^-1The mixed cation perovskite thin film is obtained by removing the precursor solvent after rotating for 90s at the rotating speed, the thickness is between 80nm and 2nm, and the position of an emission spectrum is 525 nm. Wherein, when the excitation power is 100P_thThe gain coefficient is 1800cm^-1And has high gain characteristic.

Example four

1) CsBr, MABr, FABr and PbBr₂Dissolving in anhydrous N-N Dimethylformamide (DMF) at a molar ratio of 2.2:0.03:0.07:1, and stirring at 40 deg.C for 20 hr to form [ Cs_0.87(MAFA)_0.13]PbBr₃The precursor solution of the 3D mixed cation perovskite has the concentration of 0.4mol L^-1；

2) PEABr and PbBr₂Dissolving in anhydrous dimethyl sulfoxide (DMSO) at a ratio of 2:1 to form 2D Perovskite (PEA)₂PbBr₄The precursor solution of (2) has a concentration of 0.3mol L^-1；

3) Mixing the precursor solutions of the two perovskites in equal volume to obtain the multi-cation mixed perovskite material [ [ Cs ]_0.87(MAFA)_0.13]PbBr₃]_0.5[(PEA)₂PbBr₄]_0.3The precursor solution of (1);

4) dripping 50 μ L of the above perovskite precursor solution on a glass substrate with a liquid-transfering gun, spreading the solution, staying on the substrate for 10min, and then 6000r min^-1The mixed cation perovskite thin film obtained by removing the precursor solvent is rotated for 30s at the rotating speed, the thickness is 85nm, the roughness is 1.9nm, and the position of an emission spectrum is 524 nm. Wherein, when the excitation power is 100P_thThe gain coefficient is 1500cm^-1And has high gain characteristic.

EXAMPLE five

1) CsBr, MABr, FABr and PbBr₂Dissolving in anhydrous dimethyl sulfoxide (DMSO) at a molar ratio of 2.2:0.03:0.07:1, heating at 30 deg.C and stirring for 24 hr to form [ Cs_0.87(MAFA)_0.13]PbBr₃The precursor solution of the 3D mixed cation perovskite has the concentration of 0.5mol L^-1；

2) NMABr and PbBr₂Dissolving in anhydrous dimethyl sulfoxide (DMSO) at a ratio of 2:1 to form 2D perovskite (NMA)₂PbBr₄The precursor solution of (2) has a concentration of 0.5mol L^-1；

3) Mixing the precursor solutions of the two perovskites in equal volume to obtain the multi-cation mixed perovskite material [ [ Cs ]_0.87(MAFA)_0.13]PbBr₃]_0.5[(NMA)₂PbBr₄]_0.3The precursor solution of (1);

4) dripping 30 μ L of the above perovskite precursor solution on a glass substrate with a liquid-transferring gun, spreading the solution, staying on the substrate for 10min, and then allowing the solution to stand for 3000r min^-1The mixed cation perovskite thin film obtained by removing the precursor solvent is rotated for 120s at the rotating speed, the thickness is 70nm, the roughness is 1.3nm, and the position of an emission spectrum is 510 nm. The stability data are shown in FIG. 2, where FIG. 2a is the gain threshold of the sample as a function of time, and FIG. 2 shows that after 4 months of storage in the glove box, the threshold did not change, indicating that the resulting material was very stableSex; FIG. 2b is a graph showing the amplified spontaneous emission intensity of a sample subjected to continuous light irradiation with laser pulses as a function of time, and FIG. 2b shows that the amplified spontaneous emission intensity does not decrease for 8 hours under continuous irradiation with laser pulses, indicating that the material has excellent light resistance.

Wherein, when the excitation power is 100P_thThe gain coefficient is 2200cm^-1And has high gain characteristic.

EXAMPLE six

1) CsBr, MABr, FABr and PbBr₂Dissolving in anhydrous dimethyl sulfoxide (DMSO) at a molar ratio of 2.2:0.05:0.05:1, heating at 50 deg.C and stirring for 15 hr to form [ Cs_0.87(MAFA)_0.13]PbBr₃The precursor solution of the 3D mixed cation perovskite has the concentration of 0.5mol L^-1；

3) Mixing the precursor solutions of the two perovskites in equal volume to obtain the multi-cation mixed perovskite material [ [ Cs ]_0.87(MAFA)_0.13]PbBr₃]_0.5[(NMA)₂PbBr₄]_0.2The precursor solution of (1);

4) dripping 20 μ L of the above perovskite precursor solution on a glass substrate with a liquid-transferring gun, spreading the solution, standing on the substrate for 8min, and then allowing the solution to stand for 3000r min^-1The mixed cation perovskite thin film obtained by removing the precursor solvent is rotated for 200s at the rotating speed, the thickness is 75nm, the roughness is 1.1nm, and the position of an emission spectrum is 530 nm.

Wherein, when the excitation power is 100P_thThe gain coefficient is 2500cm^-1And has high gain characteristic.

EXAMPLE seven

1) CsBr, MABr, FABr and PbBr₂Dissolving in anhydrous dimethyl sulfoxide (DMSO) at a molar ratio of 2.2:0.04:0.06:1, heating at 40 deg.C and stirring for 18 hr to form [ Cs_0.87(MAFA)_0.13]PbBr₃The precursor solution of the 3D mixed cation perovskite has the concentration of 0.5mol L^-1；

4) dripping 30 μ L of the above perovskite precursor solution on a glass substrate with a liquid-transferring gun, spreading the solution, staying on the substrate for 12min, and then allowing the solution to stand for 6000r min^-1The mixed cation perovskite thin film obtained by removing the precursor solvent is rotated for 100s at the rotating speed, the thickness is 30nm, the roughness is 0.5nm, and the position of an emission spectrum is 526 nm.

Wherein, when the excitation power is 70P_thThe gain coefficient is 3000cm^-1And has a high gain characteristic as shown in fig. 4.

Example eight

1) CsBr, MABr, FABr and PbBr₂Dissolving in anhydrous dimethyl sulfoxide (DMSO) at a molar ratio of 2.2:0.03:0.07:1, heating at 50 deg.C and stirring for 24 hr to form [ Cs_0.87(MAFA)_0.13]PbBr₃The precursor solution of the 3D mixed cation perovskite has the concentration of 0.5mol L^-1；

2) BABr and PbBr₂Dissolving in anhydrous dimethyl sulfoxide (DMSO) at a ratio of 2:1 to form 2D perovskite (BA)₂PbBr₄The precursor solution of (2) has a concentration of 0.3mol L^-1；

3) Mixing the precursor solutions of the two perovskites in equal volume to obtain the multi-cation mixed perovskite material [ [ Cs ]_0.87(MAFA)_0.13]PbBr₃]_0.5[(BA)₂PbBr₄]_0.3The precursor solution of (1);

4) dripping 60 μ L of the above perovskite precursor solution on a glass substrate with a liquid-transferring gun, spreading the solution, staying on the substrate for 10min, and then allowing the solution to stand for 1000r min^-1The mixed cation perovskite thin film is obtained by removing the precursor solvent at the rotating speed of 120s, the thickness is 300nm, the roughness is 5nm, and the position of an emission spectrum is 530 nm.

Wherein, when the excitation power is 80P_thThe gain coefficient is 1200cm^-1And has high gain characteristic.

Example nine

1) CsBr, MABr and PbBr₂Dissolving in anhydrous dimethyl sulfoxide (DMSO) at a molar ratio of 2.2:0.01:1, heating at 45 deg.C and stirring for 24 hr to form [ Cs_0.87(MA)_0.13]PbBr₃The precursor solution of the 3D mixed cation perovskite has the concentration of 0.5mol L^-1；

3) Mixing the precursor solutions of the two perovskites in equal volume to obtain the multi-cation mixed perovskite material [ [ Cs ]_0.87(MA)_0.13]PbBr₃]_0.5[(BA)₂PbBr₄]_0.3The precursor solution of (1);

4) dripping 70 μ L of the above perovskite precursor solution on a silicon dioxide substrate by a liquid transfer gun, spreading the solution, staying on the substrate for 10min, and then performing 4000r min^-1Rotational speed of 120sThe thickness of the mixed cation perovskite thin film obtained by removing the precursor solvent is 110nm, the roughness is 2.3nm, and the position of an emission spectrum is 524 nm.

Wherein, when the excitation power is 90P_thThe gain coefficient is 1300cm^-1And has high gain characteristic.

Example ten

1) CsBr, FABr and PbBr₂Dissolving in anhydrous dimethyl sulfoxide (DMSO) at a molar ratio of 2.2:0.01:1, heating at 35 deg.C and stirring for 24 hr to form [ Cs_0.87FA_0.13]PbBr₃The precursor solution of the 3D mixed cation perovskite has the concentration of 0.5mol L^-1；

3) Mixing the precursor solutions of the two perovskites in equal volume to obtain the multi-cation mixed perovskite material [ (Cs)_0.87FA_0.13)PbBr₃]_0.5[(BA)₂PbBr₄]_0.1The precursor solution of (1);

4) dripping 50 μ L of the above perovskite precursor solution on a silicon dioxide substrate with a liquid-transferring gun, spreading the solution, staying on the substrate for 10min, and then allowing the solution to stand for 3000r min^-1The mixed cation perovskite thin film obtained by removing the precursor solvent is rotated for 120s at the rotating speed, the thickness is 90nm, the roughness is 1.7nm, and the position of an emission spectrum is 523 nm.

Wherein, when the excitation power is 100P_thThe gain coefficient is 1600cm^-1And has high gain characteristic.

EXAMPLE eleven

1) CsBr, FABr and PbBr₂According to the molar ratio of 2.2:0.01:1Dissolving in anhydrous dimethyl sulfoxide (DMSO), heating and stirring at 30 deg.C for 24 hr to form [ Cs_0.87FA_0.13]PbBr₃The precursor solution of the 3D mixed cation perovskite has the concentration of 0.5mol L^-1；

3) Mixing the precursor solutions of the two perovskites in equal volume to obtain the multi-cation mixed perovskite material [ (Cs)_0.87FA_0.13)PbBr₃]_0.5[(NMA)₂PbBr₄]_0.2The precursor solution of (1);

4) dripping 20 μ L of the above perovskite precursor solution on a silicon dioxide substrate with a liquid-transferring gun, spreading the solution, staying on the substrate for 10min, and then allowing the solution to stand for 3000r min^-1The mixed cation perovskite thin film is obtained by removing the precursor solvent after rotating for 150s at the rotating speed, the thickness is 70nm, the roughness is 1nm, and the position of an emission spectrum is 522 nm.

Wherein, when the excitation power is 100P_thThe gain coefficient is 3000cm^-1As shown in fig. 3 and 4, has a high gain characteristic.

Example twelve

1) CsBr, FABr and PbBr₂Dissolving in anhydrous dimethyl sulfoxide (DMSO) at a molar ratio of 2.2:0.01:1, heating at 45 deg.C and stirring for 24 hr to form [ Cs_0.87FA_0.13]PbBr₃The precursor solution of the 3D mixed cation perovskite has the concentration of 0.5mol L^-1；

2) PEABr and PbBr₂Dissolving in anhydrous dimethyl sulfoxide (DMSO) at a ratio of 2:1 to form 2D Perovskite (PEA)₂PbBr₄The precursor solution of (2) has a concentration of 0.1mol L^-1；

3) Mixing the precursor solutions of the two perovskites in equal volume to obtainMulti-cation mixed perovskite material [ (Cs)_0.87FA_0.13)PbBr₃]_0.5[(PEA)₂PbBr₄]_0.1The precursor solution of (1);

4) dripping 30 μ L of the above perovskite precursor solution on a glass substrate with a liquid-transferring gun, spreading the solution, staying on the substrate for 8min, and then allowing the solution to stand for 3000r min^-1The mixed cation perovskite thin film obtained by removing the precursor solvent is rotated for 150s at the rotating speed, the thickness is between 78nm, the roughness is between 1.6nm (as shown in figure 5), and the position of an emission spectrum is 527 nm.

Wherein, when the excitation power is 100P_thWhile the gain coefficient is 2700cm^-1And has high gain characteristic.

EXAMPLE thirteen

1) FABr, MABr and PbBr₂Dissolving in anhydrous dimethyl sulfoxide (DMSO) at a molar ratio of 2.2:0.01:1, heating and stirring at 45 deg.C for 24 hr to form [ FA%_0.87MA_0.13]PbBr₃The precursor solution of the 3D mixed cation perovskite has the concentration of 0.5mol L^-1；

2) PEABr and PbBr₂Dissolving in anhydrous dimethyl sulfoxide (DMSO) at a ratio of 2:1 to form 2D Perovskite (PEA)₂PbBr₄The precursor solution of (2) has a concentration of 0.2mol L^-1；

3) Mixing the precursor solutions of the two perovskites in equal volume to obtain the multi-cation mixed perovskite material [ (FA)_0.87MA_0.13)PbBr₃]_0.5[(PEA)₂PbBr₄]_0.2The precursor solution of (1);

4) dripping 60 μ L of the above perovskite precursor solution on a sapphire substrate by using a liquid-transferring gun, spreading the solution, staying on the substrate for 5min, and then performing 6000r min^-1The mixed cation perovskite thin film is obtained by removing the precursor solvent at the rotating speed of 80s, the thickness is 50nm, the roughness is 0.6nm, and the position of an emission spectrum is 517 nm.

Wherein, when the excitation power is 60P_thThe gain coefficient is 1700cm^-1And has high gain characteristic.

Example fourteen

1) FABr, MABr and PbBr₂Dissolving in anhydrous dimethyl sulfoxide (DMSO) at a molar ratio of 2.2:0.01:1, heating and stirring at 30 deg.C for 24 hr to form [ FA%_0.87MA_0.13]PbBr₃The precursor solution of the 3D mixed cation perovskite has the concentration of 0.5mol L^-1；

2) BABr and PbBr₂Dissolving in anhydrous dimethyl sulfoxide (DMSO) at a ratio of 2:1 to form 2D perovskite (BA)₂PbBr₄The precursor solution of (2) has a concentration of 0.2mol L^-1；

3) Mixing the precursor solutions of the two perovskites in equal volume to obtain the multi-cation mixed perovskite material [ (FA)_0.87MA_0.13)PbBr₃]_0.5[(BA)₂PbBr₄]_0.2The precursor solution of (1);

4) dripping 60 μ L of the above perovskite precursor solution on a sapphire substrate by using a liquid-transferring gun, spreading the solution, staying on the substrate for 5min, and then performing 6000r min^-1The mixed cation perovskite thin film is obtained by removing the precursor solvent at the rotating speed of 80s, the thickness is 50nm, the roughness is 0.6nm, and the position of an emission spectrum is 517 nm. Wherein, when the excitation power is 60P_thThe gain coefficient is 1300cm^-1And has high gain characteristic.

Example fifteen

1) FABr, MABr and PbBr₂Dissolving in anhydrous dimethyl sulfoxide (DMSO) at a molar ratio of 2.2:0.01:1, heating and stirring at 35 deg.C for 24 hr to form [ FA%_0.87MA_0.13]PbBr₃The precursor solution of the 3D mixed cation perovskite has the concentration of 0.5mol L^-1；

3) Mixing the precursor solutions of the two perovskites in equal volume to obtain the multi-cation mixed perovskite material [ (FA)_0.87MA_0.13)PbBr₃]_0.5[(NMA)₂PbBr₄]_0.2The precursor solution of (1);

4) dripping 30 μ L of the above perovskite precursor solution on a glass substrate with a liquid-transferring gun, spreading the solution, staying on the substrate for 5min, and then allowing the solution to stand for 6000r min^-1The mixed cation perovskite thin film is obtained by removing the precursor solvent at the rotating speed of 80s, the thickness is 40nm, the roughness is 0.6nm, and the position of an emission spectrum is 515 nm.

Wherein, when the excitation power is 60P_thThe gain coefficient is 1050cm^-1And has high gain characteristic.

Example sixteen

1) CsBr, FABr, MABr and PbBr₂Dissolving in anhydrous dimethyl sulfoxide (DMSO) at a molar ratio of 2.2:0.02:0.08:1, heating and stirring at 50 deg.C for 16 hr to form [ Cs_0.87(FAMA)_0.13]PbBr₃The precursor solution of the 3D mixed cation perovskite has the concentration of 0.5mol L^-1；

3) Mixing the precursor solutions of the two perovskites in equal volume to obtain the multi-cation mixed perovskite material [ (Cs)_0.87(FAMA)_0.13)PbBr₃]_0.5[(PEA)₂PbBr₄]_0.2The precursor solution of (1);

4) dripping 20 μ L of the above perovskite precursor solution on a sapphire substrate by using a liquid-transferring gun, spreading the solution, staying on the substrate for 5min, and then performing 6000r min^-1The mixed cation perovskite thin film obtained by removing the precursor solvent is rotated for 180s at the rotating speed, the thickness is 70nm, the roughness is 1.2nm, and the position of an emission spectrum is 523 nm.

Wherein, when the excitation power is 120P_thThe gain coefficient is 3000cm^-1And has high gain characteristic.

Example seventeen

1) CsBr, FABr, MABr and PbBr₂Dissolving in anhydrous dimethyl sulfoxide (DMSO) at a molar ratio of 2.2:0.03:0.07:1, heating at 30 deg.C and stirring for 16 hr to form [ Cs_0.87(FAMA)_0.13]PbBr₃The precursor solution of the 3D mixed cation perovskite has the concentration of 0.5mol L^-1；

2) NMABr and PbBr₂Dissolving in anhydrous dimethyl sulfoxide (DMSO) at a ratio of 2:1 to form 2D perovskite (NMA)₂PbBr₄The precursor solution of (2) has a concentration of 0.4mol L^-1；

3) Mixing the precursor solutions of the two perovskites in equal volume to obtain the multi-cation mixed perovskite material [ (Cs)_0.87(FAMA)_0.13)PbBr₃]_0.5[(NMA)₂PbBr₄]_0.4The precursor solution of (1);

4) dripping 50 μ L of the above perovskite precursor solution on a sapphire substrate by using a liquid-transferring gun, spreading the solution, staying on the substrate for 15min, and then performing 4000r min^-1The mixed cation perovskite thin film is obtained by removing the precursor solvent at the rotating speed of 180s, the thickness is 120nm, the roughness is 3.2nm, and the position of an emission spectrum is 530 nm.

Wherein, when the excitation power is 100P_thWhile the gain coefficient was 2600cm^-1And has high gain characteristic.

EXAMPLE eighteen

1) CsBr, FABr, MABr and PbBr₂Dissolving in anhydrous dimethyl sulfoxide (DMSO) at a molar ratio of 2.2:0.03:0.07:1, heating at 35 deg.C and stirring for 16 hr to form [ Cs_0.87(FAMA)_0.13]PbBr₃The precursor solution of the 3D mixed cation perovskite has the concentration of 0.5mol L^-1；

2) BABr and PbBr₂Dissolving in anhydrous dimethyl sulfoxide (DMSO) at a ratio of 2:1 to form 2D perovskite (BA)₂PbBr₄The precursor solution of (2) has a concentration of 0.4mol L^-1；

3) Mixing the precursor solutions of the two perovskites in equal volume to obtain the multi-cation mixed perovskite material [ (Cs)_0.87(FAMA)_0.13)PbBr₃]_0.5[(BA)₂PbBr₄]_0.4The precursor solution of (1);

4) dripping 20 μ L of the above perovskite precursor solution on a sapphire substrate by using a liquid-transferring gun, spreading the solution, staying on the substrate for 1min, and then performing 6000r min^-1The mixed cation perovskite thin film obtained by removing the precursor solvent is rotated for 80s at the rotating speed, the thickness is 30nm, the roughness is 2.2nm, and the position of an emission spectrum is 511 nm.

Wherein, when the excitation power is 40P_thThe gain coefficient is 820cm^-1And has high gain characteristic.

Example nineteen

1) FABr, CsBr and PbBr₂Dissolving in anhydrous dimethyl sulfoxide (DMSO) at a molar ratio of 2.2:0.01:1, heating and stirring at 45 deg.C for 16 hr to form [ FA%_0.87Cs_0.13]PbBr₃The precursor solution of the 3D mixed cation perovskite has the concentration of 0.5mol L^-1；

2) PEABr and PbBr₂Dissolving in anhydrous dimethyl sulfoxide (DMSO) according to the ratio of 2:1,formation of 2D Perovskite (PEA)₂PbBr₄The precursor solution of (2) has a concentration of 0.1mol L^-1；

3) Mixing the precursor solutions of the two perovskites in equal volume to obtain the multi-cation mixed perovskite material [ (FA)_0.87MA_0.13)PbBr₃]_0.5[(PEA)₂PbBr₄]_0.1The precursor solution of (1);

4) dripping 60 μ L of the above perovskite precursor solution on a glass substrate with a liquid-transferring gun, spreading the solution, staying on the substrate for 5min, and then allowing the solution to stand for 3000r min^-1The mixed cation perovskite thin film is obtained by removing the precursor solvent by rotating for 130s at the rotating speed, the thickness is between 90nm, the roughness is between 2.6nm, and the position of an emission spectrum is 527 nm.

Wherein, when the excitation power is 50P_thThe gain coefficient is 1100cm^-1And has high gain characteristic.

Example twenty

1) CsBr, MABr and PbBr₂Dissolving in anhydrous gamma-butyrolactone at a molar ratio of 2.2:0.01:1, heating at 45 deg.C and stirring for 24 hr to form [ Cs_0.87MA_0.13]PbBr₃The precursor solution of the 3D mixed cation perovskite has the concentration of 0.5mol L^-1；

2) NMABr and PbBr₂Dissolving in anhydrous dimethyl sulfoxide (DMSO) at a ratio of 2:1 to form 2D perovskite (NMA)₂PbBr₄The precursor solution of (2) has a concentration of 0.3mol L^-1；

3) Mixing the precursor solutions of the two perovskites in equal volume to obtain the multi-cation mixed perovskite material [ (Cs)_0.87MA_0.13)PbBr₃]_0.5[(NMA)₂PbBr₄]_0.3The precursor solution of (1);

4) dripping 50 μ L of the above perovskite precursor solution on a sapphire substrate with a liquid-transfering gun, spreading the solution, staying on the substrate for 25min, and then performing 3000r min^-1The mixed cation perovskite thin film obtained by removing the precursor solvent is rotated for 120s at the rotating speed, the thickness is 250nm, the roughness is 4.6nm, and the position of an emission spectrum is 530 nm.

Wherein, when the excitation power is 100P_thThe gain coefficient is 1300cm^-1And has high gain characteristic.

The method can be realized by upper and lower limit values and interval values of intervals of process parameters (such as temperature, time and the like), and embodiments are not listed.

Conventional technical knowledge in the art can be used for the details which are not described in the present invention.

Finally, it should be noted that the above embodiments are only used for illustrating the technical solutions of the present invention and are not limited. Although the present invention has been described in detail with reference to the embodiments, it will be understood by those skilled in the art that various changes may be made and equivalents may be substituted without departing from the spirit and scope of the invention as defined in the appended claims.

Claims

1. A mixed multi-cation perovskite material thin film with optical gain characteristics is characterized in that the general chemical structural formula of the mixed multi-cation perovskite material thin film is [ (A)_0.87BxCy)PbX₃]_b[A’₂PbX₄]_c；

x is a halide anion;

b, c is 1 (0-0.8);

A_0.87in BxCy, x + y is 0.13, and 0.87 is A andthe mass ratio of the total mass of A + B + C, x is the mass ratio of B to the total mass of A + B + C, and y is the mass ratio of C to the total mass of A + B + C;

the thickness of the mixed multi-cation perovskite material film is 20 nm-200 nm; the gain coefficient is 800-3000cm^-1(ii) a The light-emitting wavelength range is 510-530 nm; the roughness is 0.5nm-5 nm.

2. The mixed polycation perovskite material thin film having optical gain characteristics as claimed in claim 1, wherein b: c is 1 (0.2-0.8).

3. A method of preparing a mixed polycationic perovskite thin film material having optical gain characteristics as claimed in claim 1 or 2, said method of preparation comprising the steps of:

1) mixing AX, BX, CX and PbX₂Dissolving in a precursor solvent according to the molar ratio of 2.2: m: n:1, wherein m + n is equal to 0.01, heating, stirring and filtering to obtain the 3D perovskite (A)_0.87BxCy)PbX₃The precursor solution of (1); wherein the 3D perovskite (A)_0.87BxCy)PbX₃The molar concentration of (A) is 0.2-0.5 mol.L^-1；

2) A' X and PbX are mixed₂Dissolving the mixture in a precursor solvent according to a molar ratio of 2:1 to form 2D perovskite A'₂PbX₄The precursor solution of (1); wherein 2D perovskite A'₂PbX₄In a molar concentration range of 0 to 0.5 mol.L^-1；

3) Mixing 3D perovskite (A)_0.87BxCy)PbX₃With 2D perovskite A'₂PbX₄The precursor solution is mixed in equal volume to obtain multi-cation mixed perovskite precursor solution;

4) and (3) dropping a proper amount of multi-cation mixed perovskite precursor solution on a substrate, spreading the solution and staying on the substrate, and spin-coating to form a film and removing the precursor solution to obtain the mixed multi-cation perovskite thin film material with the optical gain characteristic.

4. The production method according to claim 3, wherein the precursor solvent is selected from one or more of N-N dimethylformamide, dimethyl sulfoxide and γ -butyrolactone.

5. The method according to claim 3, wherein the substrate is glass, a silicon wafer, quartz, or sapphire.

6. The method according to claim 3, wherein the spin coating of step 4) is performed at a rotation speed of 1000 to 6000 r-min^-1And the time is 30-200 s.

7. Use of a thin film of a mixed multi-cation perovskite material having optical gain characteristics as claimed in claim 1 or 2 in the manufacture of a perovskite laser.