A method for preparing a perovskite thin film blue gain medium

Abstract

The application relates to a preparation method of a perovskite thin film blue light gain medium, which comprises the following steps: S1, raw material blending: dissolving perovskite precursors and polyacrylonitrile (PAN) in super-dry dimethyl sulfoxide to obtain a mixed solution; wherein the mass ratio of the polyacrylonitrile (PAN) to the perovskite precursors is (0.3-0.4):1; S2, spin coating film formation: taking the mixed solution on a glass substrate, and utilizing a spin coating method to spin coat a film in an inert gas environment to obtain the perovskite thin film blue light gain medium. The perovskite thin film prepared by the method can realize low-threshold, high-light-gain blue light lasing, and has good stability in a high-humidity environment.

Description

Technical Field

[0001] The present invention belongs to the technical field of laser gain medium materials, and in particular relates to a method for preparing a perovskite thin film blue light gain medium. Background Art

[0002] Semiconductor lasers have advantages such as ultra-small size, high efficiency, low power consumption, long life, and high-speed modulation. They are widely used in optical communications, optical information processing, laser displays, and intelligent driving. Among them, the semiconductor gain medium, as the core component of semiconductor lasers, directly determines the performance of semiconductor lasers.

[0003] The gain media of commercial semiconductor lasers are generally III-V compound semiconductors such as gallium arsenide (GaAs), indium phosphide (InP), and gallium nitride (GaN). Their growth process often relies on epitaxial growth techniques under ultra-high vacuum conditions, which requires demanding growth conditions and high equipment and energy costs. Furthermore, epitaxial growth relies on lattice matching, and the lattice mismatch between compound semiconductors and commonly used silicon substrates has greatly limited the development of semiconductor lasers. In contrast, lead halide perovskite thin films offer advantages such as high optical gain, tunable bandgap, non-epitaxial growth, and ease of integration with other optoelectronic devices, making them a strong contender for the next generation of low-cost, high-performance full-color laser gain media.

[0004] Therefore, it is necessary to propose a perovskite thin-film blue light gain medium that can achieve low-threshold, high-gain blue light lasing while also having good stability, targeting the lead halide perovskite technology route. This perovskite thin-film blue light gain medium is specifically designed for gain in the blue light region and exhibits significant optical gain characteristics in the blue light band, enabling low-threshold blue light lasing or amplification, which is of great significance for improving the performance and stability of blue lasers. Summary of the Invention

[0005] The purpose of the present invention is to provide a method for preparing a perovskite thin film blue light gain medium. The perovskite thin film prepared by this method can achieve low threshold, high optical gain blue light lasing and has good stability in a high humidity environment.

[0006] To achieve the above object, the technical solution adopted by the present invention is:

[0007] A method for preparing a perovskite thin film blue light gain medium comprises the following steps:

[0008] S1. Raw material blending: dissolving a perovskite precursor and polyacrylonitrile (PAN) in ultra-dry dimethyl sulfoxide to obtain a mixed solution; wherein the mass ratio of the polyacrylonitrile (PAN) to the perovskite precursor is (0.3-0.4):1;

[0009] S2. Spin coating: The mixed solution is placed on a glass substrate and is spin-coated in an inert gas environment to form a film to obtain a perovskite thin film blue light gain medium.

[0010] Furthermore, the perovskite precursor consists of CsCl, PbCl2 and PbBr2.

[0011] Furthermore, the concentration ratio of CsCl, PbCl2, and PbBr2 is 4:1:3. For example, in the embodiments of the present invention, the concentrations of CsCl, PbCl2, and PbBr2 are 0.12M, 0.03M, and 0.09M, respectively. The above concentrations are merely examples and do not constitute a specific limitation on the concentration of the perovskite precursor of the present invention. All concentrations within the scope of the protection concept of the present invention are within the scope of protection of the present invention.

[0012] Furthermore, the glass substrate is a pre-treated glass substrate;

[0013] The pretreatment method is as follows: the glass substrate is ultrasonically cleaned in acetone, deionized water and anhydrous ethanol in sequence for 30 minutes, blown dry with a nitrogen gun, and then placed in an oxygen plasma machine for surface treatment for 10 minutes.

[0014] Furthermore, the spin coating process in step S2 is performed in a glove box filled with nitrogen.

[0015] Furthermore, the spin coating film forming condition parameters of step S2 are: rotation speed of 2000 rpm, spin coating time of 120 s; after the spin coating is completed, the film is placed on a hot plate at 100° C. for annealing for 10 minutes.

[0016] Furthermore, the perovskite thin film blue light gain medium has a symmetrical waveguide structure of "polyacrylonitrile-perovskite-polyacrylonitrile".

[0017] Furthermore, the symmetrical waveguide structure is formed in situ during the spin coating process of the perovskite film.

[0018] Furthermore, the refractive index of the polyacrylonitrile is smaller than that of perovskite to enhance the confinement of photons; the perovskite film blue light gain medium can be at 21.9 μJ / cm 2 Blue light amplified spontaneous emission is achieved under low threshold excitation conditions.

[0019] Beneficial effects of the present invention:

[0020] (1) The polyacrylonitrile is used as an additive to be added into the perovskite precursor solution, and the high-quality perovskite film can be prepared by one-step spin coating. The polyacrylonitrile is concentratedly distributed in the buried interface and the upper surface of the film, and a natural "polyacrylonitrile-perovskite-polyacrylonitrile" symmetrical waveguide structure is formed in situ, so that the restriction of the film on the photons is enhanced. Meanwhile, the in-situ coordination coating of the perovskite grain by the polyacrylonitrile matrix can effectively passivate the defects in the perovskite and improve the ion migration barrier in the perovskite, so that the spectral stability is enhanced. In addition, the polyacrylonitrile can significantly improve the surface morphology and the film thickness, so as to reduce the scattering loss and increase the mode restriction. Finally, the perovskite film can realize low threshold and high optical gain blue lasing, and has good stability in a high humidity environment.

[0021] (2) By introducing 30%-40% mass fraction of polyacrylonitrile into the perovskite precursor solution, a natural "polyacrylonitrile-perovskite-polyacrylonitrile" sandwich structure is formed in situ during the one-step spin coating of the perovskite film. Since the refractive index of polyacrylonitrile is less than that of perovskite, a symmetrical waveguide structure can be formed, the restriction of the photons is enhanced, and the lasing characteristics of the perovskite film are improved. BRIEF DESCRIPTION OF DRAWINGS

[0022] Figure 1 The cross-sectional high-angle annular dark-field image and element distribution map of the perovskite film blue gain medium prepared in Example 1;

[0023] Figure 2 The schematic comparison diagram of the symmetrical waveguide structure of the perovskite film blue gain medium sample prepared in Example 1 (left side) and Comparative Example 1 (right side);

[0024] Figure 3 The normalized fluorescence spectra of the perovskite film of Comparative Example 1 (a) and the perovskite film of Example 1 (b) under continuous wave laser continuous irradiation;

[0025] Figure 4 The blue lasing characteristics of the perovskite film blue gain medium of Example 1, and the gain medium can realize blue amplified spontaneous emission under low threshold excitation condition of 21.9 μJ / cm 2 ;

[0026] Figure 5 The analysis diagram of the influence of different PAN addition amounts on the amplified spontaneous emission threshold of the perovskite film. DETAILED DESCRIPTION

[0027] In order to make the purpose, technical scheme and effect of the present application more clear and definite, the present application is further described in detail below. It should be understood that the specific embodiments described herein are only used to explain the present application, and are not used to limit the present application.

[0028] Example 1:

[0029] CsCl, PbCl2, PbBr2 and polyacrylonitrile (PAN) were weighed and dissolved in ultra-dry dimethyl sulfoxide, wherein the mass of CsCl, PbCl2 and PbBr2 was 20.2 mg, 8.3 mg and 30.3 mg respectively according to 1 mL of dimethyl sulfoxide, so that the concentration of CsCl, PbCl2 and PbBr2 in the precursor solution was 0.12 M, 0.03 M and 0.09 M respectively, and polyacrylonitrile (PAN) was added to the precursor solution at a mass fraction of 35%, and stirring was performed to ensure complete dissolution. The glass substrate was sequentially ultrasonically cleaned in acetone, deionized water and anhydrous ethanol for 30 min, dried by a nitrogen gun and then placed in an oxygen plasma machine for surface treatment for 10 min, and then transferred to a glove box for standby. An appropriate amount of precursor solution was taken to the center of the glass substrate (for a 15*15 mm glass substrate, the typical value was 50 microliters), and a one-step spin coating method was used to spin-coat a film at a rotation speed of 2000 revolutions per minute for 120 seconds. After spin coating, the film was placed on a heating plate at 100°C for annealing for 10 min. The entire film preparation process was carried out in a glove box filled with nitrogen, and a perovskite film blue gain medium was obtained.

[0030] Experimental analysis: as shown in Figure 1 , the cross-sectional high-angle annular dark-field image and element distribution diagram of the perovskite film blue gain medium sample prepared in Example 1; due to the presence of heavy metal lead in the perovskite, the perovskite shows obvious contrast compared with the polymer matrix. The lead element is mainly distributed in the central region of the cross-sectional direction, and the carbon element is concentratedly distributed on the upper surface and the lower surface. It shows that in the vertical direction of the film, PAN shows obvious segregation phenomenon, and is concentratedly distributed at the buried interface and the upper surface of the perovskite layer, and the perovskite is coated therein.

[0031] As shown in Figure 2 , it is a schematic diagram of the symmetric waveguide structure of "polyacrylonitrile-perovskite-polyacrylonitrile" according to the application. In Example 1, since the upper and lower surfaces of the perovskite are coated with polyacrylonitrile, and the refractive index of polyacrylonitrile is less than that of perovskite, a natural symmetric waveguide structure is formed in the film, and photons are confined in the perovskite. Correspondingly, in Comparative Example 1, since there is no coordination coating of polyacrylonitrile, there is no symmetric waveguide structure in the film, and the photon confinement effect is significantly reduced.

[0032] As shown in Figure 3 , the perovskite film of Comparative Example 1 only showed spectral shift after low-density excitation of 200 mW / cm 2 for about 20 seconds, while the perovskite film of Example 1 showed spectral shift after high-density excitation of 10 W / cm 2The blue light emission can be maintained stably even after 2 hours of continuous irradiation under high excitation density. This indicates that the spectral stability of the perovskite film is significantly improved after adding PAN.

[0033] like Figure 4 As shown in the figure, the blue light lasing characteristics of the perovskite film blue light gain medium of Example 1 are shown in the figure. The gain medium can emit blue light at 21.9 μJ / cm 2 Blue light amplified spontaneous emission is achieved under low threshold excitation conditions.

[0034] Example 2:

[0035] CsCl, PbCl₂, PbBr₂, and polyacrylonitrile (PAN) were weighed and dissolved in ultra-dry dimethyl sulfoxide. The concentrations of CsCl, PbCl₂, and PbBr₂ in the precursor solution were 0.12 M, 0.03 M, and 0.09 M, respectively. 30% by mass of polyacrylonitrile (PAN) was added to the precursor solution and stirred to ensure complete dissolution. The thin film was spin-coated using the same method as in Example 1.

[0036] Example 3:

[0037] CsCl, PbCl₂, PbBr₂, and polyacrylonitrile (PAN) were weighed and dissolved in ultra-dry dimethyl sulfoxide. The concentrations of CsCl, PbCl₂, and PbBr₂ in the precursor solution were 0.12 M, 0.03 M, and 0.09 M, respectively. 40% by mass of polyacrylonitrile (PAN) was added to the precursor solution and stirred to ensure complete dissolution. The thin film was spin-coated using the same method as in Example 1.

[0038] Comparative Example 1:

[0039] Weigh CsCl, PbCl2, and PbBr2 and dissolve them in ultra-dry dimethyl sulfoxide. The concentrations of CsCl, PbCl2, and PbBr2 in the precursor solution are 0.12 M, 0.03 M, and 0.09 M, respectively. Stir to ensure complete dissolution. The spin coating method is the same as in Example 1.

[0040] Comparative Example 2:

[0041] Weigh CsCl, PbCl2, and PbBr2 and dissolve them in ultra-dry dimethyl sulfoxide (DMSO). The concentrations of CsCl, PbCl2, and PbBr2 in the precursor solution are 0.12M, 0.03M, and 0.09M, respectively. Stir to ensure complete dissolution. Add 10% polyacrylonitrile (PAN) by weight to the precursor solution and stir to ensure complete dissolution. The thin film spin coating method is the same as in Example 1.

[0042] like Figure 5Figure 2 shows an analysis of the effect of varying PAN addition levels on the amplified spontaneous emission threshold of perovskite films. The films in Comparative Examples 1 and 2 cannot generate amplified spontaneous emission. However, Examples 1, 2, and 3, which have a naturally symmetrical waveguide structure, can achieve low-threshold amplified spontaneous emission.

[0043] While the present invention is described through the above-described embodiments to illustrate the detailed preparation methods of the present invention, the present invention is not limited to the above-described detailed preparation methods. This does not necessarily mean that the present invention must rely on the above-described products and detailed preparation methods in order to be implemented. Those skilled in the art will appreciate that any improvements to the present invention, or any combination or equivalent substitution of raw materials in the products of the present invention, fall within the scope of protection and disclosure of the present invention.

Claims

1. A method for preparing a perovskite thin film blue light gain medium, characterized in that: The steps include: S1. Raw material blending: dissolving a perovskite precursor and polyacrylonitrile (PAN) in ultra-dry dimethyl sulfoxide to obtain a mixed solution; wherein the mass ratio of the polyacrylonitrile (PAN) to the perovskite precursor is (0.3-0.4):1; S2. Spin coating: The mixed solution is applied to a glass substrate and spin-coated in an inert gas environment to form a film to obtain a perovskite thin film blue light gain medium; The perovskite thin film blue light gain medium has a symmetrical waveguide structure of "polyacrylonitrile-perovskite-polyacrylonitrile".

2. The method for preparing a perovskite thin film blue light gain medium according to claim 1, characterized in that: The perovskite precursor consists of CsCl, PbCl2 and PbBr2.

3. The method for preparing a perovskite thin film blue light gain medium according to claim 2, wherein: The concentration ratio of CsCl, PbCl2 and PbBr2 is 4:1:

3.

4. The method for preparing a perovskite thin film blue light gain medium according to claim 1, wherein: The glass substrate is a pre-treated glass substrate; The pretreatment method is as follows: the glass substrate is ultrasonically cleaned in acetone, deionized water and anhydrous ethanol in sequence for 30 minutes, blown dry with a nitrogen gun, and then placed in an oxygen plasma machine for surface treatment for 10 minutes.

5. The method for preparing a perovskite thin film blue light gain medium according to claim 4, characterized in that: The spin coating process in step S2 is performed in a glove box filled with nitrogen.

6. The method for preparing a perovskite thin film blue light gain medium according to claim 1, characterized in that: The spin coating film forming condition parameters in step S2 are: a rotation speed of 2000 rpm, a spin coating time of 120 s; and annealing on a hot plate at 100° C. for 10 min after the spin coating is completed.

7. The method for preparing a perovskite thin film blue light gain medium according to claim 1, characterized in that: The symmetrical waveguide structure is formed in situ during the spin coating process of the perovskite film.

8. The method for preparing a perovskite thin film blue light gain medium according to claim 7, characterized in that: The refractive index of the polyacrylonitrile is lower than that of the perovskite to enhance the confinement effect of photons; The perovskite thin film blue light gain medium can achieve a wavelength of 21.9 μJ / cm 2 Blue light amplified spontaneous emission is achieved under low threshold excitation conditions.

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