A method for rapidly preparing high-performance red-green-blue perovskite light-emitting films at air, room temperature

Abstract

This invention discloses a method for rapidly preparing high-performance red-green-blue perovskite luminescent thin films in air and at room temperature. The invention utilizes a confined microreactor constructed with nickel acetate and phenylethylamine: the hydration reaction between nickel acetate and water molecules in air provides energy for perovskite crystallization and limits the growth rate of the perovskite crystals, while the phenylethylamine cations prevent the lower-dimensional phase of the perovskite from further growing into a higher-dimensional phase, achieving a blue shift in the material's spectrum and realizing spectral modulation under a single halogen system. The resulting thin film achieves a color gamut of 93.1% of the Rec 2020 standard, far exceeding the NTSC standard, and a brightness exceeding 200,000 cd / m² under 365 nm UV excitation. 2 Air quality 1000 cd / m³ 2 The half-life exceeds 1000 hours under operating conditions; high-precision pixel arrays of 10160 PPI can be fabricated via laser etching. This process has low environmental barriers and low cost, making it suitable for high-definition displays, optoelectronic arrays, and information encryption.

Description

Technical Field

[0001] This invention relates to the field of perovskite thin film preparation technology, specifically to a method for achieving high-quality red, green and blue perovskite luminescent thin films with a single halogen system under air and room temperature conditions, and a technique for patterning perovskite thin films. Background Technology

[0002] Metal halide perovskites, as the latest generation of semiconductor light-emitting materials, have attracted much attention due to their tunable bandgap, high quantum yield, and strong photoluminescence, showing great potential in fields such as smart lighting, high-definition displays, and photoelectric detection. To obtain standard red, green, and blue (RGB) emission that meets display requirements and avoid spectral drift and broadening caused by phase separation in mixed halogen systems, perovskite materials with quantum confinement effects in single-halogen systems are typically prepared. These materials include small-sized perovskite quantum dots (PeQDs), nanowires, nanosheets, and quasi-2D films, allowing for spectral modulation to maintain the color purity required for display standards. Precise control of crystal size is crucial for the confinement effect. Although pure bromine or pure iodine PeQDs that meet display requirements can be prepared through quantum confinement, the increased specific surface area due to smaller quantum dot sizes significantly reduces their stability. This not only makes the synthesis process more complex and variable but also easily leads to crystal aggregation and regrowth during thin-film assembly, weakening the confinement effect. In contrast, quasi-2D films can effectively suppress the aggregation and growth of nanocrystals through encapsulation and passivation with organic layers.

[0003] However, during the crystallization process of quasi-2D perovskite films, low-dimensional and high-dimensional phases (n = 1, 2, 3, ..., ∞) grow simultaneously and disorderly, accompanied by different emission wavelengths and performance characteristics. This results in obvious impurity peaks or tails in the film spectrum, reducing spectral color purity. Furthermore, the low-dimensional phase is extremely sensitive to environmental factors such as water, oxygen, heat, and light during its formation. These factors not only limit the fabrication environment and operating scenarios of quasi-2D films, increasing production costs, but also inevitably lead to poor reproducibility of the film fabrication process, making commercial production difficult.

[0004] Therefore, developing in-situ confined growth technology suitable for perovskite thin films with a single halogen system to stably obtain a low-dimensional n-phase composition that tends to be singular is crucial for improving the quality and luminescence purity of perovskite thin films and is the key to solving the above-mentioned application bottlenecks. Summary of the Invention

[0005] To address the problems of disordered n-phase growth and suppression of natural degradation of perovskite crystals during the growth process of quasi-2D perovskite films, this invention provides a method based on nickel acetate (Ni(CH3COO)2) and phenylethylamine cations (PEA). + By leveraging the synergistic confinement effect of RGB perovskite, a method for rapidly preparing high-performance RGB perovskite luminescent films at air and room temperature was developed, and a high-resolution pixelated luminescent array was achieved on the film through continuous laser etching.

[0006] In a first aspect, the present invention provides a method for rapidly preparing high-performance red-green-blue perovskite luminescent thin films in air and at room temperature, comprising the following steps:

[0007] S1, prepare the precursor solutions corresponding to the red, green and blue perovskite films;

[0008] S2, Add nickel acetate solution to the above precursor solution, stir well and filter;

[0009] S3, in air, is coated on a substrate to obtain a red, green and blue perovskite luminescent film.

[0010] Furthermore, the precursor solution corresponding to the red perovskite film is obtained by dissolving MAI, PbI2, and PEAI in DMF solvent, wherein the molar ratio of MAI, PbI2, and PEAI is 1:1:0.4~0.7, and the concentration of the precursor solution is not greater than 1 mmol / ml.

[0011] Furthermore, the precursor solution corresponding to the green perovskite film is obtained by dissolving MABr and PbBr2 in DMF solvent, wherein the molar ratio of MABr and PbBr2 is 1:1, and the concentration of the precursor solution is no greater than 1 mmol / ml.

[0012] Furthermore, the precursor solution corresponding to the blue perovskite film is obtained by dissolving MABr, PbBr2, and PEABr in DMF solvent, wherein the molar ratio of MABr, PbBr2, and PEABr is 1:1:1~1.5, and the concentration of the precursor solution is not greater than 1 mmol / ml.

[0013] Furthermore, the nickel acetate solution concentration is 1-2 mmol / ml, and the solvent is DMF.

[0014] Furthermore, a nickel acetate solution is added to the precursor solution, wherein the molar ratio of nickel ions in the nickel acetate solution to Pb ions in the precursor solution corresponding to the red perovskite film is 1~2:1, preferably 1.5:1.

[0015] Furthermore, a nickel acetate solution is added to the above precursor solution, wherein the molar ratio of nickel ions in the nickel acetate solution to Pb ions in the precursor solution corresponding to the green perovskite film is 1~3:1, preferably 2:1.

[0016] Furthermore, a nickel acetate solution is added to the precursor solution, wherein the molar ratio of nickel ions in the nickel acetate solution to Pb ions in the precursor solution corresponding to the blue perovskite film is 1 to 4:1, preferably 3:1.

[0017] Furthermore, the thin film preparation needs to be carried out in an air atmosphere so that the moisture in the air can react with the matrix to provide energy for perovskite crystallization. Moreover, no thermal annealing is required during the thin film preparation process. The optimal environmental requirements for the preparation are a temperature range of 20-30 ℃ and a relative humidity range of 40-50%.

[0018] Furthermore, the substrate can be a rigid substrate such as glass or silicon wafer, or a flexible substrate such as polydimethylsiloxane (PDMS) or polyethylene terephthalate (PET).

[0019] Furthermore, when coating the precursor solution, small-sized perovskite films can be prepared by spin coating, or large-sized perovskite films can be prepared by blade coating, spray coating, etc. The spin coating speed is 2000-3000 rpm, the spin coating time is 45-120 seconds, and the blade coating thickness is 0.1 μm.

[0020] In a second aspect, the present invention provides an RGB perovskite luminescent thin film prepared by the method described in the first aspect.

[0021] Thirdly, the present invention provides the use of the RGB perovskite luminescent thin film prepared by the method described in the first aspect in display devices or optoelectronic devices.

[0022] Compared with the prior art, the advantages of the present invention are:

[0023] This invention utilizes a Ni(CH3COO)2 matrix coating process to transform water molecules in the air, which are prone to degrading perovskite, into a driving force for perovskite crystallization, effectively improving the air stability of the perovskite film. The entire preparation process can be completed under ambient temperature conditions, requiring only simple coating and natural solvent evaporation to form the film, eliminating the need for annealing and significantly relaxing environmental restrictions and simplifying the production process. The resulting perovskite luminescent film can be effectively spectrally controlled by adjusting the PEAX content, and due to the synergistic confinement effect between PEAX and the Ni(CH3COO)2 matrix, the disordered growth of the n-phase is suppressed, improving the purity of the emitted color. Furthermore, this film can be finely patterned through continuous laser etching to prepare high-resolution pixelated perovskite luminescent arrays, which has significant application value for optimizing image quality, readability, and immersive user experience in terminal products such as head-mounted displays and smart glasses. Attached Figure Description

[0024] To more clearly illustrate the specific embodiments of the present invention or the technical solutions in the prior art, the accompanying drawings used in the description of the specific embodiments or the prior art will be briefly introduced below.

[0025] Figure 1 This is a schematic diagram of the mechanism of the in-situ spatially confined microreactor in Example 1.

[0026] Figure 2 For the principle analysis of the perovskite thin film preparation in air in Example 1, (a) a photo of the perovskite nanocrystalline thin film prepared in air / N2, (b) a photo of the thin film prepared in N2 after being placed in air over time, (c) the in-situ PL spectrum of the spin-coated thin film without Ni(CH3COO)2, and (d) the in-situ PL spectrum of the spin-coated thin film with Ni(CH3COO)2.

[0027] Figure 3 For the principle analysis of orientation growth and synergistic confinement in Example 1, (a) adsorption energy of Ni(CH3COO)2 on different crystal planes of MAPbBr3, (b) XRD pattern of perovskite film, wherein the precursor ratio of film is Ni(CH3COO)2: PEABr: MAPbBr3 = 2: x: 1, (c) schematic diagram of orientation growth mechanism of Ni(CH3COO)2 on MAPbBr3, (d) schematic diagram of synergistic confinement mechanism of Ni(CH3COO)2 and PEABr on MAPbBr3.

[0028] Figure 4The following images show the in-situ PL spectra, luminescence intensity variation curves, and final (c) Abs-PL spectra and (d) CIE coordinates of the PL spectra during the crystallization process of perovskite thin films with different Ni(CH3COO)2 contents in Example 1. The precursor ratio is Ni(CH3COO)2: PEABr: MAPbBr3 = x: 1.5: 1 (x = 0, 1, 2, 3).

[0029] Figure 5 Photographs of films with different nickel acetate matrix contents in Application Example 2 (a) and PL spectra of blue, green and red films (b), are shown.

[0030] Figure 6 The following are the (a) brightness and (b) LT of the LED based on perovskite thin film in Application Example 3 in an air environment. 50 (3W 365 nm LED excitation, at 1000 cd / m) 2 (c) The CIE coordinates of the RGB spectrum are measured from the beginning.

[0031] Figure 7 This is a photograph of a large-area perovskite luminescent thin film prepared by coating a large-area PDMS film based on the precursor solution formulation described in Application Example 1.

[0032] Figure 8 The images show a pixel light-emitting array fabricated by continuous laser etching based on a perovskite thin film in Application Example 3, as well as a patterned demonstration image of the array thin film on an ultraviolet LED light-emitting array.

[0033] Figure 9 The results of statistical analysis and standard deviation calculation of the emission uniformity distribution based on the pixel emission array in Application Example 3 are shown. Detailed Implementation

[0034] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0035] The technical terms “first”, “second”, etc. in this application are used only to distinguish different objects and should not be construed as indicating or implying relative importance or implicitly specifying the number, specific order, or primary and secondary relationship of the indicated technical features.

[0036] The reference to "embodiment" in this application means that a particular feature, structure, or characteristic described in connection with an embodiment may be included in at least one embodiment of this application. The appearance of this phrase in various places in the specification does not necessarily refer to the same embodiment, nor is it a separate or alternative embodiment that is mutually exclusive with other embodiments.

[0037] The technical term "and / or" in this application is only a description of the relationship between related objects, indicating that there can be three kinds of relationships. For example, A and / or B can represent three situations: A exists alone, A and B exist at the same time, and B exists alone.

[0038] In addition, the character " / " in this application generally indicates that the objects before and after it are in an "or" relationship.

[0039] In this application, "multiple" means two or more (including two), and "at least one" means one or more.

[0040] It should be noted that, unless otherwise specified in the examples, the conditions should be performed under standard conditions or conditions recommended by the manufacturer. Reagents or instruments whose manufacturers are not specified are all commercially available products.

[0041] Combination Figure 1 The principle of this invention is: based on Ni(CH3COO)2 and PEA + The synergistic confinement effect of functional groups forms an in-situ spatially confined microreactor, enabling the ordered growth of low-dimensional perovskite under air and room temperature conditions. This achieves a uniform distribution of perovskite quantum wells dominated by the n=2 phase at both macroscopic and microscopic scales. The Ni(CH3COO)2 involved in the scheme is provided by Ni(CH3COO)2·4H2O, and PEA... + The radicals are provided by phenylethylamine iodide (PEAI) or phenylethylamine bromide (PEABr), and the perovskite precursor is composed of methylammonium bromide, lead bromide, methylammonium iodide, and lead iodide. The components used for blue light films are nickel acetate tetrahydrate, phenylethylamine bromide, methylammonium bromide, and lead bromide; for green light films, they are nickel acetate tetrahydrate, methylammonium bromide, and lead bromide; and for red light films, they are nickel acetate tetrahydrate, phenylethylamine iodide, methylammonium iodide, and lead iodide. All of these materials need to be dissolved in DMF solvent before use. Furthermore, the film preparation process requires an exothermic hydration reaction between ambient moisture and Ni(CH3COO)2 to drive perovskite crystallization; environmental uncertainties can affect the consistency of performance between different batches of materials.

[0042] To illustrate this invention, the following detailed description, in conjunction with figures, embodiments, and application examples, outlines the raw material formulation, preparation process, corresponding characterization methods, and applications of the RGB perovskite thin film described herein.

[0043] The chemical structures of the precursor materials for preparing thin films described in this invention are as shown in Formulas 1-4.

[0044]

[0045] Example 1:

[0046] Combination Figure 1 This invention presents a method for rapidly preparing high-performance RGB perovskite luminescent thin films in air at room temperature. The raw materials used to prepare the luminescent thin film need to be dissolved in a DMF solvent before use.

[0047] (a) Preparation of precursor solution

[0048] [1]. Solution preparation for green thin films:

[0049] Mix 0.112 g MABr, 0.367 g PbBr2, and 1 ml DMF thoroughly and set aside as solution 1.

[0050] Mix 0.498 g Ni(CH3COO)2·4H2O + 1 ml DMF thoroughly and set aside as solution 2.

[0051] To dissolve Ni(CH3COO)2·4H2O and remove the water of crystallization as quickly as possible, solution 2 is first heated at 70°C and stirred for 30 minutes (min), then cooled to room temperature for later use. When using, solution 1 and solution 2 are mixed evenly in an appropriate ratio so that the molar ratio of nickel to lead in the solution is 2:1. Then, the mixed solution is filtered using a 0.22-micron (μm) organic filter and then used for later use.

[0052] [2]. Preparation of the solution for the blue film:

[0053] Mix 0.283 g PEABr, 0.112 g MABr, 0.367 g PbBr2 + 1 ml DMF thoroughly and set aside as solution 1.

[0054] Mix 0.498 g Ni(CH3COO)2·4H2O + 1 ml DMF thoroughly and set aside as solution 2.

[0055] First, heat solution 2 at 70°C and stir for 30 minutes. Then, cool it to room temperature and set it aside. When using it, mix solution 1 and solution 2 in an appropriate ratio so that the molar ratio of nickel to lead in the solution is 3:1. Then, filter the mixed solution using a 0.22-micron (μm) organic filter and set it aside.

[0056] [3]. Preparation of solution for red film:

[0057] Mix 0.149 g PEAI, 0.159 g MAI, 0.461 g PbI2 + 1 ml DMF thoroughly and set aside as solution 1.

[0058] Mix 0.498 g Ni(CH3COO)2·4H2O + 1 ml DMF thoroughly and set aside as solution 2.

[0059] When using, first heat solution 2 at 70°C and stir for 30 minutes. Then mix solution 1 and solution 2 in an appropriate ratio so that the molar ratio of nickel to lead in the solution is 1.5:1. Then filter the mixed solution using a 0.22-micron (μm) organic filter and set aside.

[0060] (II) Preparation of perovskite luminescent thin films

[0061] First, prepare the green, blue, and red film solutions as described above. Then, coat these solutions onto the substrate. The spin coating parameters are 2000-3000 rpm (r / min) and 45-120 seconds (s). The thickness for blade coating is set to 0.1 μm.

[0062] Figure 1 The fabrication process of perovskite luminescent thin films was demonstrated, with the entire process conducted at room temperature and in air (optimal temperature 25-30℃, relative humidity 40-45%). As the DMF solvent gradually evaporates, microreactor nanoclusters formed by encapsulating the perovskite precursor in a Ni(CH3COO)2 matrix precipitate out. These clusters are tightly packed, uniformly and densely distributing the perovskite components across the entire substrate. Simultaneously, water molecules in the air gradually come into contact with the Ni(CH3COO)2 matrix and undergo an exothermic hydration reaction. Driven by this energy, the perovskite precursor begins to crystallize and emit bright, multicolored light. Figure 2 As shown, only systems in air containing a Ni(CH3COO)2 matrix exhibit significant luminescence.

[0063] Figure 3 This demonstrates the oriented growth and synergistic confinement principle of perovskite. Taking green and blue light thin film systems as examples, according to theoretical calculations, Ni(CH3COO)2 in the system tends to combine with the (100) crystal plane of the perovskite, and then the perovskite preferentially grows and crystallizes from this direction. At this time, if PEA is introduced... + If the group is present, the system will preferentially grow low-dimensional perovskite grains with n = 2 as the main component, which is the synergistic confinement effect.

[0064] (III) Spectral modulation of perovskite luminescent thin films based on synergistic confinement effect

[0065] like Figure 4As shown, the content of Ni(CH3COO)2 matrix is ​​significantly related to the distribution of perovskite n phase. When the content of Ni(CH3COO)2 is insufficient, the n phase in the system will grow disorderedly, and the emission spectrum of the film has many impurity peaks and uneven distribution. However, when Ni(CH3COO)2 is sufficient, disordered growth is suppressed, and the emission color purity of the film is also improved.

[0066] like Figure 5 The method described above utilizes a nickel acetate matrix to promote high-quality in-situ growth of perovskite in air, while simultaneously suppressing the growth of PEA-containing films. + The disordered growth of low-dimensional phases caused by functional groups improves the color purity of the film's luminescence. Based on this, we ultimately achieve precise control of the standard RGB three colors by controlling the component ratio.

[0067] Application Example 1:

[0068] Combination Figure 6 This application example demonstrates the photoluminescence properties of perovskite thin films. By coating a precursor solution onto a 3W LED with a wavelength of 365 nm using the aforementioned process, we fabricated a photoluminescent RGB-LED. The maximum brightness of the device exceeded 130,000 cd / m². 2 (Red), 200,000 cd / m 2 (Green) and 140,000 cd / m 2 (Blue). Furthermore, the backlight film exhibits good environmental stability; under air and room temperature conditions, the luminous half-life of the RGB-LED (1000 cd / m²) is... 2 The measurements were taken at 791 h, 1112 h, and 684 h, respectively. Due to the high color purity of the spectrum, the CIE coordinates of the RGB-LED are: red: (0.696, 0.303), green: (0.134, 0.773), and blue: (0.147, 0.041). Its color gamut range can reach 91.3% of the Rec.2020 standard, far exceeding the range of the NTSC standard, which is very important for improving the color saturation of display devices.

[0069] Application Example 2:

[0070] Combination Figure 7 This application example demonstrates a large-area (15×20 square centimeters) flexible RGB perovskite luminescent film prepared on a PDMS substrate using the above-described RGB perovskite film preparation method.

[0071] Application Example 3:

[0072] Combination Figure 8This application example demonstrates a pixel-emitting array based on the aforementioned RGB perovskite thin film under continuous laser etching. The equipment used is a 405 nm continuous laser, equipped with an optical microscope focusing system and a translation platform. The prepared thin film sample is placed at the center of the translation platform, and the Z-axis of the platform is adjusted for coarse focusing. Then, the minimum energy of the 405 nm laser (0.2 mW) is used for precise focusing. After confirming the precise processing focal length, the laser energy is adjusted until the film emission can be completely "quenched." The translation platform program for array fabrication is executed. The X-axis speed in the program is 0.3 mm / s, and the Y-axis speed is 0.3 mm / s. The motion trajectory of the translation stage is set to first move the X-axis by 1 mm, then move the Y-axis by 10 μm, repeating this process 100 times to form a grid-like array; the X and Y motion modes are then switched, with the Y-axis moving by 1 mm first, then the X-axis moving by 10 μm, repeating this process 100 times to form a 2540 PPI grid-like array. The PPI can be adjusted by changing the X and Y step sizes in the program, and a minimum area array of 10160 PPI can be achieved. The minimum quenching energy for the blue film is 30 mW, for the green film it is 20 mW, and for the red film it is 7.5 mW. Finally, by attaching the backlight film to a commercial UV LED array display, we fabricated an RGB three-color patterned array display with a PPI of 2540.

[0073] Figure 9 The pixel uniformity statistics of these light-emitting arrays are given, and the standard deviation (σ) of these data is calculated. Except for the red light array with 5080 PPI, the σ of the other arrays is less than 0.1, which proves the feasibility of laser etching array technology.

[0074] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, and not to limit them. Although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some or all of the technical features therein. Such modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the embodiments of the present invention, and they should all be covered within the scope of the claims and specification of the present invention.

Claims

1. A method for rapidly preparing high-performance red-green-blue perovskite luminescent thin films in air and at room temperature, characterized in that, The steps include the following: S1, prepare the precursor solutions corresponding to the red, green and blue perovskite films; S2, Add nickel acetate solution to the above precursor solution, stir well and filter; S3, in air, is coated on a substrate to obtain a red, green and blue perovskite luminescent film.

2. The method as described in claim 1, characterized in that, The precursor solution for the red perovskite film is obtained by dissolving MAI, PbI2, and PEAI in DMF solvent, wherein the molar ratio of MAI, PbI2, and PEAI is 1:1:0.4~0.7, and the concentration of the precursor solution is not greater than 1 mmol / ml; and / or, the precursor solution for the green perovskite film is obtained by dissolving MABr and PbBr2 in DMF solvent, wherein the molar ratio of MABr and PbBr2 is 1:1, and the concentration of the precursor solution is not greater than 1 mmol / ml; and / or, the precursor solution for the blue perovskite film is obtained by dissolving MABr, PbBr2, and PEABr in DMF solvent, wherein the molar ratio of MABr, PbBr2, and PEABr is 1:1:1~1.5, and the concentration of the precursor solution is not greater than 1 mmol / ml.

3. The method as described in claim 1, characterized in that, The nickel acetate solution concentration is 1-2 mmol / ml, and the solvent is DMF.

4. The method as described in claim 1, characterized in that, at A nickel acetate solution is added to the above precursor solution, wherein the molar ratio of nickel ions in the nickel acetate solution to Pb ions in the precursor solution corresponding to the red perovskite film is 1~2:1, preferably 1.5:1; and / or, the molar ratio of nickel ions in the nickel acetate solution to Pb ions in the precursor solution corresponding to the green perovskite film is 1~3:1, preferably 2:1; and / or, the molar ratio of nickel ions in the nickel acetate solution to Pb ions in the precursor solution corresponding to the blue perovskite film is 1~4:1, preferably 3:

1.

5. The method as described in claim 1, characterized in that, In air, a red, green and blue perovskite luminescent film is obtained by coating on a substrate at an ambient temperature of 20-30 ℃ and a relative humidity of 40-50%.

6. The method as described in claim 1, characterized in that, The substrate is a rigid substrate such as glass or silicon wafer, or a flexible substrate such as polydimethylsiloxane (PDMS) or polyethylene terephthalate (PET).

7. The method as described in claim 1, characterized in that, When applying the precursor solution, spin coating, scraping coating, or spraying methods are used.

8. An RGB perovskite luminescent thin film prepared by the method according to any one of claims 1-7.

9. Use of an RGB perovskite luminescent thin film prepared by the method of any one of claims 1-7 in a display device or optoelectronic device.

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