Thickness-adjustable blue light quasi-two-dimensional perovskite thin film and preparation method thereof

Abstract

The invention discloses a thickness-adjustable blue light quasi-two-dimensional perovskite thin film and a preparation method thereof. An organic-inorganic hybrid chlorine source is used, organic components are used for regulating and controlling the crystal boundary property of quasi-two-dimensional perovskite, pi-pi stacking caused by benzene ring stacking is broken, formation of small n phases (nlt; 4) is inhibited, light emission is concentrated on the n phases larger than or equal to 4, and therefore the half-peak width of fluorescence emission is narrowed, and the color purity is improved. The crystal is induced to orderly grow perpendicular to the substrate by using nucleation sites on the surface of inorganic components (such as inorganic nanocrystalline residues), so that a compact thick-layer structure is formed, and a carrier transport path is optimized. The synergistic effect of the organic components and the inorganic components is exerted, and the performance of the quasi-two-dimensional perovskite light-emitting layer is optimized. Besides, the band gap is adjusted through accurate release of chloride ions, only blue shift characteristic peaks with n larger than or equal to 4 are reserved in an absorption spectrum, fluorescence emission is subjected to blue shift, spurious signals are eliminated, and high-purity blue light emission is achieved.

Description

Technical Field

[0001] The present invention belongs to the technical field of perovskite materials, and in particular relates to a thickness-adjustable blue light quasi-two-dimensional perovskite film and a preparation method thereof. Background Art

[0002] Quasi-two-dimensional perovskite materials, with their advantages of high exciton binding energy, strong quantum confinement, wide spectral coverage, and simple synthesis, have become a key research direction for the development of high-performance perovskite light-emitting diodes (LEDs). While the external quantum efficiency of red and green quasi-two-dimensional perovskite LEDs has approached theoretical limits, blue-emitting LEDs lag far behind. As a crucial component of full-spectrum displays, the challenges of fabricating high-performance blue LEDs urgently need to be addressed. Fabricating thicker emitting layers is a key strategy for improving the performance of blue devices: thicker perovskite layers enhance light-coupling efficiency and reduce the impact of interface defects, thereby increasing internal quantum efficiency and suppressing efficiency roll-off at high currents. They also optimize the spatial distribution of carriers and the radiative recombination area, reducing the electric field strength per unit volume, inhibiting ion migration, and improving device stability.

[0003] However, existing technologies face two key challenges. First, traditional inorganic chlorine sources (such as PbCl2 and CsCl) have low solubility and weak chemical reactivity in polar solvents, resulting in insufficient ion supply during film formation. This leads to problems such as inadequate crystallization, uneven phase distribution, and high defect density, severely limiting the preparation of thick light-emitting layers (>100 nm). Second, perovskite ions synthesized using inorganic chlorine sources have low activation energies and are prone to phase separation under the influence of an electric field, leading to shifts in the electroluminescence spectrum or the generation of spurious peaks, reducing color purity and spectral stability. Furthermore, existing methods struggle to precisely control the crystal growth direction and phase distribution, resulting in disordered crystal arrangement, low carrier transport efficiency, and increased Auger recombination, further limiting device performance. Overcoming the technical barriers to thick-layer preparation and crystal orientation control is a key path to achieving efficient and stable blue-emitting quasi-two-dimensional perovskite LEDs. Summary of the Invention

[0004] To address the above-mentioned issues, the present invention provides a thickness-tunable blue-light quasi-two-dimensional perovskite film and its preparation method. Using an organic-inorganic hybrid chlorine source (i.e., CsPbCl3 nanocrystals coated with oleylamine), a blue-light-emitting quasi-two-dimensional perovskite light-emitting layer (LEL) with a narrow phase distribution, stable structure, ordered crystal arrangement perpendicular to the substrate, and a thickness exceeding 100 nanometers is prepared. The organic component regulates the phase distribution and modifies the grain boundary properties during the preparation process, thereby inhibiting the formation of small n-phases and passivating surface defects, thereby improving the crystallinity and fluorescence quantum efficiency of the quasi-two-dimensional perovskite light-emitting layer. The inorganic component regulates the crystal growth direction during the preparation process, achieving an ordered crystal structure perpendicular to the substrate, further increasing the thickness and stabilizing the crystal structure, thereby smoothing carrier transport in the light-emitting layer and improving the stability of the quasi-two-dimensional perovskite film. The organic component released by the chlorine source during the introduction passivates halogen vacancy defects in the quasi-two-dimensional perovskite grain boundaries and acts as a physical barrier, blocking halogen migration between crystals, inhibiting phase separation, and improving the material's spectral stability.

[0005] Specifically, the present invention is prepared by the following method: (1) Prepare an organic-inorganic chlorine source solution; the organic-inorganic chlorine source is an oleylamine-coated perovskite nanocrystal, and the nanocrystal core contains releasable Cl ions; the organic-inorganic hybrid chlorine source is highly soluble in polar reagents and can quickly release oleylamine chlorine and inorganic ion clusters, which is beneficial to improving the crystallinity of the quasi-two-dimensional perovskite nanocrystals and promoting the formation of thick perovskite films. Secondly, given that the organic-inorganic hybrid chlorine source is incompletely decomposed, a small-sized inorganic nanocrystal core remains. The inorganic core surface has a large number of surface nucleation sites for adsorbing ions or ion clusters, inducing the oriented growth of the quasi-two-dimensional perovskite, forming a crystal structure perpendicular to the substrate and orderly arranged, further increasing the thickness of the quasi-two-dimensional perovskite light-emitting layer.

[0006] (2) Prepare a quasi-two-dimensional perovskite precursor solution; dissolve CsBr, PbBr2, and PEABr in anhydrous dimethyl sulfoxide solution at a molar ratio of 1.05:1:1.15; then add polyethylene oxide (PEO) and dimethyl biguanide (O-Tg) to the solution, heat to 60°C and stir for 8 hours, and then cool to room temperature; (3) Preparation of quasi-two-dimensional blue light perovskite film: The quasi-two-dimensional blue light perovskite film was prepared by spin coating in a nitrogen-filled glove box. First, 70 μL of quasi-two-dimensional perovskite precursor solution was spin-coated on the substrate at a speed of 4000 rpm for 40 seconds, and then 80 μL of organic-inorganic chlorine source solution was added to the film. After spin coating at a speed of 2000 rpm for 40 seconds, the film was annealed at 80°C for 5 minutes to obtain a quasi-two-dimensional perovskite film that emits blue light.

[0007] Furthermore, the perovskite nanocrystal in step 1 is CsPbCl3.

[0008] Furthermore, the preparation method of the organic-inorganic chlorine source in step 1 is: 1) preparing an oleate precursor, wherein the oleate precursor is cesium oleate; 2) Preparation of oleylamine-coated perovskite nanocrystals: PbCl2 and ODE were placed in a three-necked flask and vacuum-degassed and dried at 120°C for 1 hour. Oleylamine (OLA), oleic acid (OA), and tri-n-octylphosphine (TOP) were added to the flask and heated to 180°C after the solution became clear. An oleate precursor preheated to 100°C was injected into the mixture, reacted for 5 seconds, and then cooled to room temperature in an ice-water bath. 3) Washing: Centrifuge the mixture obtained in step 2 at 5000 rpm for 10 minutes to obtain a precipitate; disperse the precipitate in octane; add three volumes of methyl acetate to the octane solution, and centrifuge at 10,000 rpm for 10 minutes to obtain an organic-inorganic chlorine source, wherein the organic-inorganic chlorine source is dispersed in the octane to form a solution with a concentration of no more than 45 mg / mL.

[0009] Furthermore, the concentration of PbCl2 in ODE is 37.8 mM; and the volume ratio of ODE, OLA, OA, TOP and oleate precursor is 10:1:1:1:1.

[0010] Furthermore, the concentrations of polyethylene oxide (PEO) and dimethyl biguanide (O-Tg) in step 2 are 2 mg / mL and 5.33 mg / mL.

[0011] Furthermore, the spin coating is performed on a coater.

[0012] Furthermore, the substrate is an organic hole transport layer, obtained by spin-coating a hole transport layer solution (using a solvent such as water or chlorobenzene) onto patterned conductive glass under a nitrogen atmosphere, followed by high-temperature annealing (100 to 150°C) for 15-30 minutes. The hole transport layer aligns with the valence band energy levels of the perovskite layer, reducing the hole injection barrier.

[0013] Organic-inorganic chlorine sources decompose rapidly into oleylamine chloride and PbCl6 when exposed to polar solvents. 4- or PbCl 6-x (4+x)- Among them, the inorganic ion group can exchange with bromide ions to form PbBrxCl 6-x 4- or PbBryCl 6-x-y (4+x+y)-These ion clusters have an octahedral configuration and strong chemical reaction activity. They can quickly participate in the crystallization and growth of quasi-two-dimensional perovskite, improve the crystallinity of quasi-two-dimensional perovskite, reduce the formation of by-products, and thus increase the thickness of the quasi-two-dimensional perovskite light-emitting layer.

[0014] The organic component, oleylamine chloride, partially decomposes into oleylamine and chloride ions, while the remaining component exists as oleylamine chloride. The decomposed chloride ions can be directly used in the crystallization and growth of quasi-two-dimensional perovskites. Oleylamine chloride and oleylamine act on the perovskite grain boundaries, disrupting the π-π stacking formed by benzene rings, thereby inhibiting the formation of small n-phase (n < 4) perovskites, narrowing the phase distribution, and improving the perovskite phase purity and fluorescence color purity. They also modulate grain boundary properties, enhance crystal structure integrity, passivate surface defects, and increase ion mobility, thereby improving fluorescence quantum efficiency, stabilizing fluorescence emission, and fabricating high-efficiency, spectrally stable electroluminescent devices.

[0015] Furthermore, the organic-inorganic hybrid chlorine source decomposes from the outside inward when exposed to polar solvents, leaving a portion of the inorganic core. The surface of the residual inorganic core can adsorb ions and ion clusters, serving as nucleation sites for the quasi-two-dimensional perovskite. It also acts as a support and template, inducing oriented growth of the perovskite, forming an orderly crystal structure perpendicular to the substrate, further increasing the thickness of the quasi-two-dimensional perovskite film. This crystal arrangement can reduce the number of longitudinal grain boundaries, enhance longitudinal carrier transport, lower the carrier transport barrier, and enable the preparation of high-efficiency blue light devices.

[0016] The present invention also provides a thickness-adjustable blue light quasi-two-dimensional perovskite film prepared by the above method.

[0017] The present invention is beneficial in that: (1) The quasi-two-dimensional perovskite prepared by the present invention exhibits blue light emission at 483 nanometers, and the half-peak width of its fluorescence emission is only 24 nanometers; the absorption spectrum only detects the absorption peak when n≥4, effectively inhibiting the formation of small n-phase perovskite and improving the phase purity of the perovskite.

[0018] (2) The stability of the prepared quasi-two-dimensional perovskite is significantly improved. Under the same air environment, the fluorescence half-life is 8 hours, and the fluorescence center hardly moves within 8 hours. Moreover, its electroluminescence spectrum does not shift under the action of an electric field, and the color purity is well maintained. BRIEF DESCRIPTION OF THE DRAWINGS

[0019] Figure 1 Scanning electron microscope images of quasi-two-dimensional perovskite light-emitting layers of different thicknesses prepared with different concentrations of organic-inorganic hybrid chlorine sources.

[0020] Figure 2 Compared with the existing technology, this technical route prepares the thickness of quasi-two-dimensional perovskite.

[0021] Figure 3 (a) is the fluorescence emission spectrum, Figure 3 (b) is an absorption spectrum diagram; QD-induced represents Example 1, and pristine represents Comparative Example 1.

[0022] Figure 4 Transmission electron microscope photographs of the cross-section of the quasi-two-dimensional perovskite film prepared in Example 1 under (a) bright field and (b) dark field conditions.

[0023] Figure 5 Fluorescence stability of blue light quasi-two-dimensional perovskite prepared in Example 1 (a) and Comparative Example 2 (b).

[0024] Figure 6 The electrospectral stability of the blue light quasi-two-dimensional perovskite light-emitting layer prepared in Example 1 (a) and Comparative Example 2 (b) was investigated. DETAILED DESCRIPTION

[0025] The following examples are used to further illustrate the present invention. Their purpose is to illustrate the present invention and should not be construed as limiting the scope of the present invention. Unless otherwise specified, all references are by weight and weight percentage.

[0026] Unless otherwise specified, the raw materials used in the present invention are conventional commercial products; the methods used in the present invention are conventional methods in the art unless otherwise specified.

[0027] The embodiments of the present invention are further described below with reference to a number of embodiments.

[0028] It should be clear that the embodiments described are only part of the embodiments of this application, not all of the embodiments. Based on the embodiments in this application, all other embodiments obtained by ordinary technicians in this field without making creative work are within the scope of protection of this application.

[0029] The terms used in the embodiments of the present application are only for the purpose of describing specific embodiments and are not intended to limit the present application. The singular forms "a", "an", "the" and "the" used in the embodiments of the present application and the appended claims are also intended to include plural forms unless the context clearly indicates otherwise.

[0030] Example 1 1) Preparation of cesium oleate precursor: Cs2CO3 (814.0 mg), oleic acid (2.6 mL), and ODE (30.0 mL) were added to a 50 mL three-necked flask to obtain cesium oleate (Cs-OA). The mixture was then stirred and degassed under vacuum at 120°C. After 1 hour, nitrogen was introduced into the mixture and the mixture was heated to 150°C. Heating was stopped when the Cs2CO3 was completely dissolved. 2) Preparation of CsPbCl3 nanocrystals: 105.0 mg of PbCl2 and 10 mL of ODE were placed in a 50 mL three-necked flask, then vacuum-degassed and dried at 120°C for 1 hour. 1 mL of oleylamine (OLA), 1 mL of oleic acid (OA), and 1 mL of tri-n-octylphosphine (TOP) were quickly added to the flask. After the solution became clear, the temperature was raised to 180°C. 1 mL of Cs-OA, preheated to 100°C, was quickly injected into the mixture. After reacting for 5 seconds, the mixture was cooled to room temperature in an ice-water bath. 3) Purification: The crude solution was purified by centrifugation at 5,000 rpm for 10 minutes. The supernatant was discarded, and the precipitate was dispersed in 2 mL of octane. 6 mL of methyl acetate was added to the octane solution, and purification was continued at 10,000 rpm for another 10 minutes. Finally, the precipitate was redispersed in octane to form colloidal solutions of organic-inorganic chlorine sources at different concentrations: 20 mg / mL, 25 mg / mL, 35 mg / mL, and 45 mg / mL.

[0031] 4) Prepare a quasi-2D perovskite precursor solution: Dissolve CsBr, PbBr2, and PEABr in 1.5 mL of anhydrous dimethyl sulfoxide (DMSO) at a molar ratio of 1.05:1:1.15. Then, add 3 mg of polyethylene oxide (PEO) and 8 mg of dimethylbiguanidine (O-Tg). Heat the mixture to 60°C and stir for 8 hours before cooling to room temperature.

[0032] 5) Preparation of quasi-two-dimensional blue-light perovskite films: Quasi-two-dimensional blue-light perovskite films were prepared by spin coating in a nitrogen-filled glove box. First, 70 μL of the quasi-two-dimensional precursor solution was spin-coated on the substrate at 4000 rpm for 40 seconds. Then, 80 μL of an organic-inorganic chlorine source solution was added to the film. A second spin coating step was performed at 2000 rpm for 40 seconds. After annealing at 80°C for 5 minutes, a blue-light-emitting quasi-two-dimensional perovskite film was obtained.

[0033] like Figure 1 As shown, the quasi-two-dimensional blue perovskite films obtained with 20 mg / mL, 25 mg / mL, 35 mg / mL, and 45 mg / mL organic-inorganic chlorine source solutions correspond to 70 nm, 80 nm, 90 nm, and 105 nm, respectively. The quasi-two-dimensional perovskite films prepared by this invention are thicker and can be continuously adjusted between 40 and 100 nm, breaking the current technical barriers to preparing quasi-two-dimensional perovskite light-emitting layers.

[0034] like Figure 4As shown, the quasi-two-dimensional perovskite prepared in this embodiment has a crystal arrangement perpendicular to the substrate and parallel to each other. This crystal structure can effectively reduce vertical grain boundaries, lower the carrier transport barrier, and increase carrier mobility, thereby helping to improve carrier transport in LEDs and achieve high external quantum efficiency.

[0035] Comparative Example 1 CsBr, PbBr2, PbCl2, and PEABr were dissolved in 1.5 mL of DMSO (dimethyl sulfoxide) at a molar ratio of 1.05:0.9:0.1:1.15. The mixture was then stirred at 60°C for 12 hours. The resulting solution, a precursor solution for the quasi-two-dimensional perovskite, was then filtered and transferred to a nitrogen-filled glove box. 70 μL of this precursor solution was spin-coated onto a substrate at 4000 rpm for 40 seconds and then annealed at 80°C for 5 minutes to produce a blue-light-emitting quasi-two-dimensional perovskite film. The resulting quasi-two-dimensional perovskite film was only 40 nm thick.

[0036] The prepared quasi-two-dimensional perovskite has a fluorescence emission at 502 nm ( Figure 3 The green line in the figure does not belong to blue light emission, and its luminescence peak is at 420-440 nm, which is the fluorescence emission of small n-phase perovskite ( Figure 3 The local enlarged view in a) shows the corresponding absorption spectrum also showing the absorption peaks of multiple crystal phases (i.e., there are absorption peaks of n=1, 2, 3, and n≥4, Figure 3 b), indicating that the material phase distribution is wide and the purity is poor. The quasi-two-dimensional perovskite prepared in Example 1 emits fluorescence at 483 nm ( Figure 3 The orange line in the figure shows blue light emission, and the half-peak width of its fluorescence emission (24 nanometers) is narrower than that of the conventional technology route (27 nanometers), indicating that the blue-light quasi-two-dimensional perovskite of the present invention has higher color purity. Furthermore, compared with Comparative Example 1, the fluorescence emission of Example 1 does not show fluorescence emission from the small n-phase perovskite between 400 and 440 nanometers, and the corresponding absorption spectrum only detects the absorption peak for n ≥ 4 (due to the introduction of chloride ions, the absorption peak for n ≥ 4 is blue-shifted compared to the conventional route), indicating that this technology route can effectively inhibit the formation of small n-phase perovskite and improve the phase purity of the perovskite.

[0037] Comparative Example 2 CsBr, PbBr2, PbCl2, and PEABr were dissolved in 1.5 mL of DMSO (dimethyl sulfoxide) at a molar ratio of 1.05:0.55:0.45:1.15. The mixture was then stirred at 60°C for 12 hours. The solution was then filtered, and the resulting clear solution, serving as the quasi-two-dimensional perovskite precursor solution, was transferred to a nitrogen-filled glove box. 70 μL of this quasi-two-dimensional perovskite precursor solution was spin-coated onto a substrate at 4000 rpm for 40 seconds and then annealed at 80°C for 5 minutes to produce a blue-light-emitting quasi-two-dimensional perovskite film.

[0038] like Figure 5 As shown, the blue-light quasi-two-dimensional perovskite prepared in Comparative Example 2 has poor fluorescence stability. Its fluorescence half-life (half-life is the time required for the fluorescence intensity to decay to half of its initial value) in air is only 55 minutes, and its fluorescence center red-shifts from 474 nm to 482 nm after 1 hour ( Figure 5 b). In comparison, the blue-light quasi-two-dimensional perovskite prepared in Example 1 showed significantly improved stability. Under the same air environment, the fluorescence half-life was 8 hours, and the fluorescence center barely shifted within that 8-hour period. This experimental data demonstrates that the technology invented in this patent can improve the stability of quasi-two-dimensional perovskites.

[0039] like Figure 6 As shown, the quasi-two-dimensional perovskite light-emitting layer of Comparative Example 2 ( Figure 6 b) Under the action of an electric field, ion migration causes the electroluminescence spectrum to gradually redshift, resulting in poor luminescence stability and color purity. In contrast, the quasi-two-dimensional perovskite light-emitting layer of Example 1 effectively inhibits ion migration, and its electroluminescence spectrum does not shift under the action of an electric field, maintaining good color purity.

[0040] Hybrid organic-inorganic chlorine sources significantly optimize the luminescence properties of quasi-two-dimensional perovskites by synergistically regulating the crystallization process and grain boundary properties. The organic components (e.g., oleylamine chloride) anchor the grain boundaries during the initial crystallization phase, disrupting the π-π stacking caused by benzene ring accumulation. This suppresses the formation of the small n phase (n<4) and concentrates luminescence in the n≥4 phase, thereby narrowing the half-width of the fluorescence emission and improving color purity. This mechanism also prevents carrier capture and nonradiative recombination by defect states in the small n phase, promoting efficient energy transfer to the large n phase. The inorganic components (e.g., the inorganic nanocrystal core) induce orderly crystal growth perpendicular to the substrate through surface nucleation sites, forming a dense, uniformly oriented thick layer structure and optimizing carrier transport pathways. The precise release of chloride ions further modulates the band gap, retaining only the characteristic blue-shifted peak for n≥4 in the absorption spectrum while completely suppressing the absorption peak of the small n phase. Compared to conventional techniques (fluorescence peak at 502 nm, accompanied by spurious emission from the small n-phase at 420-440 nm), this technology blue-shifts the fluorescence emission to 483 nm and eliminates spurious signals in the shorter wavelength region, achieving high-purity blue light emission. The physical barrier effect of the organic components at the grain boundaries also inhibits ion migration and phase separation, ensuring the stability of the electroluminescence spectrum.

[0041] The above data fully demonstrate that the experimental scheme involved in the patent of this invention is extremely creative, which can realize the preparation of thick quasi-two-dimensional perovskite light-emitting layers and can achieve continuous adjustment between 40-100 nanometers; and this technical route can induce crystal orientation growth, realize orderly arrangement of crystals, improve the fluorescence quantum efficiency, stability and color purity of the perovskite light-emitting layer, and carrier mobility, and then prepare high-efficiency electroluminescent devices with stable emission spectra, which will help promote the practical application of perovskite materials in the fields of display, laser and light detection.

[0042] The above embodiments describe in detail the structure, features and effects of the present invention. The above are only preferred embodiments of the present invention. Any changes made in accordance with the concept of the present invention, or modifications to equivalent embodiments with equivalent changes, which do not exceed the scope covered by the specification, should be within the scope of protection of the present invention.

Claims

1. A method for preparing a thickness-adjustable blue light quasi-two-dimensional perovskite film, characterized in that: The following steps are involved: (1) preparing an organic-inorganic chlorine source solution; the organic-inorganic chlorine source is oleylamine-coated perovskite nanocrystals, wherein the nanocrystal core contains releasable Cl ions; (2) Prepare a quasi-two-dimensional perovskite precursor solution; dissolve CsBr, PbBr2, and PEABr in anhydrous dimethyl sulfoxide solution at a molar ratio of 1.05:1:1.15; then add polyethylene oxide (PEO) and dimethyl biguanide (O-Tg) to the solution, heat to 60°C and stir for 8 hours, and then cool to room temperature; (3) Preparation of quasi-two-dimensional blue light perovskite film: The quasi-two-dimensional blue light perovskite film was prepared by spin coating in a nitrogen-filled glove box. First, 70 μL of quasi-two-dimensional perovskite precursor solution was spin-coated on the substrate at a speed of 4000 rpm for 40 seconds, and then 80 μL of organic-inorganic chlorine source solution was added to the film. After spin coating at a speed of 2000 rpm for 40 seconds, the film was annealed at 80°C for 5 minutes to obtain a quasi-two-dimensional perovskite film that emits blue light.

2. The preparation method according to claim 1, characterized in that The perovskite nanocrystal in step 1 is CsPbCl3.

3. The preparation method according to claim 1, characterized in that The preparation method of the organic-inorganic chlorine source in step 1 is: 1) preparing an oleate precursor, wherein the oleate precursor is cesium oleate; 2) Preparation of oleylamine-coated perovskite nanocrystals: PbCl2 and 1-octadecene (ODE) were placed in a flask, degassed under vacuum at 120°C, and dried for 1 hour. Oleylamine (OLA), oleic acid (OA), and tri-n-octylphosphine (TOP) were added to the flask, and after the solution became clear, the temperature was raised to 180°C. The oleate precursor, preheated to 100°C, was injected into the mixture, reacted for 5 seconds, and then the mixture was cooled to room temperature in an ice-water bath. 3) Washing: Centrifuge the mixture obtained in step 2 at 5000 rpm for 10 minutes to obtain a precipitate; disperse the precipitate in octane; add three volumes of methyl acetate to the octane solution, centrifuge at 10,000 rpm for 10 minutes to obtain an organic-inorganic chlorine source, and disperse the organic-inorganic chlorine source in octane to obtain an organic-inorganic chlorine source solution having a concentration of no more than 45 mg / mL.

4. The method according to claim 3, characterized in that The concentration of PbCl2 in ODE is 37.8 mM; the volume ratio of ODE, OLA, OA, TOP and oleate precursor is 10:1:1:1:

1.

5. The method according to claim 1, wherein The concentrations of polyethylene oxide (PEO) and dimethyl biguanide (O-Tg) in step 2 are 2 mg / mL and 5.33 mg / mL.

6. The method according to claim 1, characterized in that The spin coating is performed on a coater.

7. The method according to claim 1, characterized in that The substrate is an organic hole transport layer, which is obtained by spin-coating a hole transport layer solution (the solvent is water or chlorobenzene) on patterned conductive glass under a nitrogen atmosphere and annealing at a high temperature of 100 to 150° C. for 15-30 minutes.

8. A thickness-adjustable blue light quasi-two-dimensional perovskite film prepared by the method of claim 1.

Images