A composition for preparing deep blue quasi-two-dimensional perovskite and its application

Abstract

The present invention discloses a composition for preparing deep blue light-emitting quasi-two-dimensional perovskites and its application. The raw materials for preparing the composition include cesium bromide, lead bromide, lead chloride, and 2-acryloyloxyethyl N-butylcarbamate. By introducing 2-acryloyloxyethyl N-butylcarbamate as a key additive, the present invention precisely inhibits the overgrowth of the high-n phase (i.e., the perovskite phase with a higher number of layers) in the quasi-two-dimensional perovskites, thereby achieving fine tuning of the optical properties of the perovskite material. When the perovskite thin film emits deep blue light, its photoluminescence quantum yield (PLQY) reaches 93.4%.

Description

Technical Field

[0001] The present invention belongs to the technical field of electroluminescent materials and device preparation, and particularly relates to a composition for preparing perovskite, a preparation method thereof, and an application thereof. Background Art

[0002] Blue perovskite light-emitting diodes (PeLEDs), especially in the field of sky-blue PeLEDs, are booming at an unprecedented speed. The huge application potential shown in the field of commercial LED displays indicates the arrival of a technological revolution. For full-color LED displays that pursue ultimate color reproduction, meeting the requirement of (0.14, 0.08) in the CIE 1931 chromaticity coordinates is an essential part of achieving high-definition picture quality. However, current blue PeLEDs on the market (whose CIE y value is often lower than 0.08) lag significantly behind PeLEDs in other spectral ranges in terms of device efficiency, which has become the main bottleneck restricting their wide application. Therefore, developing deep blue perovskite thin films with high efficiency is not only a frontier topic in the scientific research community but also an urgent need to promote the LED technology to a higher level. Among many candidate materials, quasi-two-dimensional perovskite has become the preferred material for preparing high-performance blue perovskite thin films due to its unique structure and excellent performance. Its chemical formula L 2 (APbX 3 ) n-1 PbX 4 In, the change of the n value can flexibly regulate the number of lead halide octahedron layers, thereby opening up a new way to precisely adjust the bandgap and luminescence characteristics of the material. On the road to optimizing blue light emission, additive engineering has demonstrated its indispensable advantages. First of all, by finely regulating the n value, the bandgap of the emitter can be effectively narrowed, realizing the precise positioning and emission of blue light. Particularly crucial is that the complex system of quasi-two-dimensional perovskite is composed of multiple low dimensions with different n values intertwined. The energy cascade transfer mechanism between these phases provides a new perspective for exploring the optimization path of blue light emission performance. By carefully controlling the distribution and content ratio of the two-dimensional phase, the non-radiative recombination loss during the transmission of the excited state is significantly reduced, thereby significantly improving the luminescence efficiency.

[0003] In the existing solutions, mixing halogen ions (mainly a mixture of bromide ions and chloride ions) and constructing a quasi-two-dimensional perovskite structure of pure bromide ions are currently the two main strategies for adjusting the perovskite bandgap to achieve blue shift of the light color of perovskite materials. However, although a blue light quasi-two-dimensional perovskite structure of pure bromide ions can be constructed by introducing large steric hindrance organic ligands to realize the blue light emission of low-dimensional phases with a relatively wide bandgap, it is very difficult to regulate the phase distribution in quasi-two-dimensional perovskite, and the coexistence of perovskite phases with different n values is likely to occur. Moreover, the energy transfer from low-dimensional phases to high-dimensional phases is relatively inefficient, resulting in the difficulty of achieving efficient blue light emission in blue perovskite light-emitting diodes.

[0004] Therefore, there is an urgent need to develop a blue light perovskite thin film to solve the problem of low luminous efficiency of current blue light perovskite light emitting diodes. Summary of the Invention

[0005] The present invention aims to solve at least one of the technical problems existing in the above prior art. To this end, the present invention provides a composition for preparing deep blue quasi-two-dimensional perovskite, and the blue light perovskite thin film prepared therefrom significantly improves the luminous efficiency.

[0006] The present invention also provides a deep blue quasi-two-dimensional perovskite thin film.

[0007] The present invention also provides a method for preparing the deep blue quasi-two-dimensional perovskite thin film.

[0008] The present invention also provides a blue light perovskite light emitting diode, which is prepared from the deep blue quasi-two-dimensional perovskite thin film.

[0009] According to the first aspect of the present invention, there is provided a composition for preparing deep blue quasi-two-dimensional perovskite, and the raw materials for preparing the composition include: cesium bromide, lead bromide, lead chloride, and 2-acryloyloxyethyl N-butylcarbamate.

[0010] The embodiments according to the first aspect of the present invention have at least the following beneficial effects:

[0011] The present invention introduces BCOEA (2-acryloyloxyethyl N-butylcarbamate, CAS: 63225-53-6) as a key additive. The core of this innovative strategy lies in that the BCOEA additive precisely inhibits the overgrowth of the high-n phase (i.e., the perovskite phase with a higher number of layers) in quasi-two-dimensional perovskites through its unique molecular structure and chemical properties, thereby achieving fine tuning of the optical properties of perovskite materials. Specifically, the introduction of the BCOEA additive not only promotes the crystallization optimization of the perovskite film but also significantly induces a blue shift of the spectrum, accurately shifting the emission peak from the original 467 nm (unmodified PL emission wavelength) to 461 nm, successfully achieving precise positioning in the deep blue light region. This achievement is of milestone significance for fields such as display technology, solid-state lighting, and optical communication, as it greatly broadens the application scope of perovskite luminescent materials in color regulation. Notably, the perovskite film containing the BCOEA additive achieves deep blue light emission while its photoluminescence quantum yield (PLQY) soars to an astonishing 93.4%. This value represents a qualitative leap compared to the perovskite film without the BCOEA additive (PLQY is only 22.9%), fully demonstrating the excellent ability of the BCOEA additive in enhancing the luminescence efficiency of perovskite materials. A high PLQY not only means more light energy is effectively utilized but also indicates that the material can exhibit more excellent performance in practical applications.

[0012] In summary, the BCOEA additive strategy of the present invention not only achieves a major breakthrough in the blue shift of the spectrum and deep blue light emission of the perovskite film but also significantly improves the luminescence efficiency of the material.

[0013] In some embodiments of the present invention, the raw materials for preparing the composition further include: an organic ligand, and the organic ligand includes phenethylammonium bromide and its fluorine-substituted compounds and phenethylammonium chloride and its fluorine-substituted compounds.

[0014] In some embodiments of the present invention, the phenethylammonium bromide and its fluorine-substituted compounds include at least one of phenethylammonium bromide, 2-fluorophenethylammonium bromide, 3-fluorophenethylammonium bromide, and 4-fluorophenethylammonium bromide.

[0015] In some embodiments of the present invention, the phenethylammonium chloride and its fluorine-substituted compounds include at least one of phenethylammonium chloride, 2-fluorophenethylammonium chloride, 3-fluorophenethylammonium chloride, and 4-fluorophenethylammonium chloride.

[0016] In some embodiments of the present invention, the raw materials for preparing the composition further include: formamidinium hydrobromide; and / or, the formamidinium hydrobromide includes at least one of formamidinium hydrobromide, methylammonium bromide, and propylammonium bromide.

[0017] In some embodiments of the present invention, the raw materials for preparing the composition further include: small molecule inorganic bromides;

[0018] The small molecule inorganic bromides include at least one of lithium bromide, sodium bromide, zinc bromide and rubidium bromide.

[0019] In some embodiments of the present invention, in terms of molar ratio, the cesium bromide, lead bromide, lead chloride, organic ligand, formamidinium hydrobromide and small molecule inorganic bromide are 1.0-1.2:x:1-x:1.1-1.3:0.1-0.3:0.1-0.3; x is 0.4-0.5.

[0020] In some embodiments of the present invention, in the composition, the concentration of Pb 2+ is 0.08-0.2 mmol / ml.

[0021] According to the second aspect of the present invention, a deep blue light quasi-two-dimensional perovskite film is provided, and the deep blue light quasi-two-dimensional perovskite film is prepared from the composition described above.

[0022] According to the third aspect of the present invention, a method for preparing the deep blue light quasi-two-dimensional perovskite film is provided, including: coating a solution of the composition of the deep blue light quasi-two-dimensional perovskite onto a substrate, and heating and annealing the obtained primary film to obtain the deep blue light quasi-two-dimensional perovskite film.

[0023] In some embodiments of the present invention, the method for preparing the solution of the composition for preparing the deep blue light quasi-two-dimensional perovskite includes: dissolving cesium bromide, lead bromide, lead chloride, organic ligand, formamidinium hydrobromide, small molecule inorganic bromide and 2-acryloyloxyethyl N-butylcarbamate in an organic solvent, obtaining a perovskite precursor solution, and heating it at 30-80 °C for more than 4 h in a glove box filled with nitrogen under a dark environment.

[0024] In some embodiments of the present invention, the addition amount of 2-acryloyloxyethyl N-butylcarbamate is 0.1-2 vol% of the perovskite precursor solution.

[0025] In some embodiments of the present invention, the solvent includes dimethyl sulfoxide.

[0026] In some embodiments of the present invention, in the perovskite precursor solution, the concentration of Pb 2+ is 0.08-0.2 mmol / ml.

[0027] Controlling Pb 2+ A concentration within the above range helps to optimize the quality, performance, and stability of the perovskite thin film.

[0028] In some embodiments of the present invention, the substrate is a pretreated substrate.

[0029] In some embodiments of the present invention, the steps of the pretreatment include:

[0030] A1. Immerse the substrate in a cleaning solution and ultrapure water respectively, and then use ultrasonic waves to clean the substrate.

[0031] A2. Place the cleaned substrate on a hot stage or in an oven at 100 - 200 °C for drying.

[0032] A3. Perform plasma cleaning on the dried substrate for 5 - 30 min.

[0033] In some embodiments of the present invention, the coating method includes spin coating; the rotation speed of the spin coating is 3000 - 5000 rpm; the time of the spin coating is 30 - 200 s.

[0034] In some embodiments of the present invention, the annealing temperature is 50 - 90 °C.

[0035] In some embodiments of the present invention, the annealing time is 1 - 10 min.

[0036] In some embodiments of the present invention, the annealing time is 1 - 5 min.

[0037] Within the above annealing time, the thin film exhibits the most ideal deep blue light emission characteristics, with its PL peak precisely located at 461 nm. Compared with the PL peak position of 465 nm when annealed for 1 min, an effective blue shift towards the short wavelength direction is achieved, indicating that appropriate annealing treatment can effectively promote the optimization of the internal structure of the thin film, reduce defects, and thus enhance the purity and efficiency of blue light emission. At the same time, an appropriate annealing treatment time can effectively promote the optimization and stability of the internal structure of the material, reduce non-radiative transition paths, thereby prolonging the relaxation time of excited state electrons and enhancing the efficiency of fluorescence radiation.

[0038] According to the fourth aspect of the present invention, a blue light perovskite light emitting diode is proposed, and the blue light perovskite light emitting diode is prepared from the above-mentioned deep blue light quasi-two-dimensional perovskite thin film. BRIEF DESCRIPTION OF THE DRAWINGS

[0039] The following further describes the present invention with reference to the drawings and embodiments, where:

[0040] Figure 1 are the photoluminescence (PL) spectra of Example 1, Example 2, and Example 3.

[0041] Figure 2 PL spectra of Example 1, Comparative Example 1 and Example 4;

[0042] Figure 3 Fitted curves of transient fluorescence lifetime spectra of Example 1, Example 2 and Example 3;

[0043] Figure 4 Fitted curves of transient fluorescence lifetime spectra of Example 1, Comparative Example 1 and Example 4;

[0044] Figure 5 UV-visible absorption spectra of Example 1, Comparative Example 1 and Example 4;

[0045] Figure 6 Photoluminescence quantum yield (PLQY) test charts of Example 1, Example 2 and Example 3;

[0046] Figure 7 PLQY test charts of Example 1, Comparative Example 1 and Example 4. Detailed implementation manners

[0047] The terms "preferably", "more preferably", etc. in the present invention refer to embodiments of the present invention that can provide certain beneficial effects in certain cases. However, in the same case or other cases, other embodiments may also be preferred. In addition, the description of one or more preferred embodiments does not imply that other embodiments are not available, nor is it intended to exclude other embodiments from the scope of the present invention.

[0048] When a numerical range is disclosed herein, the above range is considered continuous and includes the minimum and maximum values of the range, as well as each value therebetween. Further, when the range refers to integers, each integer between the minimum and maximum values of the range is included. In addition, when multiple ranges are provided to describe features or characteristics, the ranges can be combined. In other words, unless otherwise specified, all ranges disclosed herein should be understood to include any and all sub-ranges subsumed therein.

[0049] Next, the technical solutions in the embodiments of the present invention will be clearly and completely described in conjunction with the embodiments of the present invention. Obviously, the described embodiments are only a part of the embodiments of the present invention, rather than all of the embodiments. All other embodiments obtained by those of ordinary skill in the art based on the embodiments of the present invention without creative efforts shall fall within the scope of the present invention.

[0050] The reagents, methods and equipment used in the present invention, unless otherwise specified, are all conventional reagents, methods and equipment in the technical field.

[0051] Example 1

[0052] This example provides a composition for preparing deep blue light quasi-two-dimensional perovskite and the obtained deep blue light quasi-two-dimensional perovskite thin film. Specifically:

[0053] The preparation method of the composition for preparing deep blue light quasi-two-dimensional perovskite is as follows:

[0054] A1: Mix cesium bromide (CsBr), lead bromide (PbBr 2 ), lead chloride (PbCl 2 ), phenethylammonium bromide (PEABr), 2-fluoro phenethylammonium chloride (o-F-PEACl), formamidinium hydrobromide (FABr), and lithium bromide (LiBr) in a molar ratio of 1:0.5:0.5:0.6:0.6:0.15:0.15. Then add 0.8 vol% of additive material BCOEA (2-acryloyloxyethyl N-butylcarbamate, CAS: 63225-53-6, the volume ratio of BCOEA in the perovskite precursor containing solvent is 0.8%). The solvent for all materials is dimethyl sulfoxide (DMSO). Finally, keep the concentration of Pb 2+ at 0.10 mmol / ml. Place the prepared perovskite precursor solution in a glove box filled with nitrogen and heat it on a hot stage at 40 °C in the dark for at least 4 hours.

[0055] The preparation method of the deep blue light quasi-two-dimensional perovskite thin film is as follows:

[0056] S1: Immerse the substrate in the cleaning solution and ultrasonically clean it for 60 min. Then immerse the substrate in ultrapure water and ultrasonically clean it for 60 min. During this process, the ultrapure water needs to be replaced every 20 min to ensure that there is no residual cleaning solution on the substrate.

[0057] S2: Place the cleaned substrate on a hot stage at 150 °C for drying, and the heating time is not less than 5 min to ensure that there is no moisture on the entire substrate.

[0058] S3: Perform plasma cleaning (PLASMA) on the dried substrate for 15 min.

[0059] S4: Transfer the surface-treated substrate into a glove box filled with inert gas (N 2 ), spin-coat the prepared perovskite precursor on the substrate at a spin-coating speed of 5000 rpm for 100 s. Immediately perform annealing after rotation, the annealing temperature is 60 °C, and the annealing time is 3 min. After cooling, a quasi-two-dimensional deep blue light perovskite thin film is obtained.

[0060] Example 2

[0061] This embodiment provides a composition for preparing deep blue light quasi-two-dimensional perovskite and the obtained deep blue light quasi-two-dimensional perovskite thin film. The difference between this embodiment and Embodiment 1 lies in that in the preparation method S4 of the deep blue light quasi-two-dimensional perovskite thin film, the annealing time is 1 min, and the other conditions are the same.

[0062] Example 3

[0063] This embodiment provides a composition for preparing deep blue light quasi-two-dimensional perovskite and the obtained deep blue light quasi-two-dimensional perovskite thin film. The difference between this embodiment and Embodiment 1 lies in that in the preparation method S4 of the deep blue light quasi-two-dimensional perovskite thin film, the annealing time is 5 min, and the other conditions are the same.

[0064] Example 4

[0065] This embodiment provides a composition for preparing deep blue light quasi-two-dimensional perovskite and the obtained deep blue light quasi-two-dimensional perovskite thin film. The difference between this embodiment and Embodiment 1 lies in that in the preparation method S4 of the deep blue light quasi-two-dimensional perovskite thin film, the content of additive BCOEA is different. Specifically, 1.6 vol% of additive material BCOEA is added, and the other conditions are the same.

[0066] Example 5

[0067] This embodiment provides a composition for preparing deep blue light quasi-two-dimensional perovskite and the obtained deep blue light quasi-two-dimensional perovskite thin film. The difference between this embodiment and Embodiment 1 lies in that in the preparation method of the composition of the deep blue light quasi-two-dimensional perovskite, phenethylammonium bromide is replaced with 2-fluorophenethylammonium bromide, and the other conditions are the same.

[0068] Example 6

[0069] This embodiment provides a composition for preparing deep blue light quasi-two-dimensional perovskite and the obtained deep blue light quasi-two-dimensional perovskite thin film. The difference between this embodiment and Embodiment 1 lies in that in the preparation method of the composition of the deep blue light quasi-two-dimensional perovskite, the molar ratio of 2-fluorophenethylammonium chloride is reduced. Specifically, cesium bromide (CsBr), lead bromide (PbBr 2 ), lead chloride (PbCl 2 ), phenethylammonium bromide (PEABr), 2-fluorophenethylammonium chloride, formamidinium hydrobromide (FABr), and lithium bromide (LiBr) are mixed in a molar ratio of 1:0.5:0.5:0.6:0.5:0.15:0.15, and the other conditions are the same.

[0070] Comparative Example 1

[0071] This embodiment provides a composition for preparing deep blue light quasi-two-dimensional perovskite and the deep blue light quasi-two-dimensional perovskite thin film prepared therefrom. The difference between this embodiment and Embodiment 1 is that additive BCOEA is not introduced in the preparation method of the composition of the deep blue light quasi-two-dimensional perovskite, and the remaining conditions are the same.

[0072] Comparative Example 2

[0073] This embodiment provides a composition for preparing deep blue light quasi-two-dimensional perovskite and the deep blue light quasi-two-dimensional perovskite thin film prepared therefrom. The difference between this embodiment and Embodiment 1 is that N-(2-hydroxyethyl) butylcarbamate (CAS: 13105-54-9) is introduced in the preparation method of the composition of the deep blue light quasi-two-dimensional perovskite to replace additive BCOEA, and the remaining conditions are the same.

[0074] Test Example

[0075] Figure 1 It is the photoluminescence (PL) spectrogram of Embodiment 1 (annealing for 3 min), Embodiment 2 (annealing for 1 min) and Embodiment 3 (annealing for 5 min). This figure not only intuitively presents the close connection between the adjustment of the annealing process parameters and the optical properties of the thin film, but also deeply reveals the importance of optimizing the annealing time for improving the luminescence performance of the thin film. It can be clearly observed from the figure that as the annealing time prolongs, the PL peak position of the thin film shows a significant blue shift phenomenon, but it is not a linear change. Specifically, when the annealing time is set to 3 min, the thin film exhibits the most ideal deep blue light emission characteristics, and its PL peak is precisely located at 461 nm. Compared with the PL peak position of 465 nm when annealing for 1 min, it realizes an effective blue shift towards the short wavelength direction, indicating that appropriate annealing treatment can effectively promote the optimization of the internal structure of the thin film, reduce defects, and thus enhance the purity and efficiency of blue light emission. Further, when the annealing time is extended to 5 min, although the blue shift trend continues, the PL peak moves to 468 nm. This change may imply that too long annealing time may introduce new structural changes or defects, which instead has a certain adverse effect on deep blue light emission. Therefore, for this thin film system, annealing for 3 min is the key process parameter to achieve the best deep blue light emission performance, which is of great significance for the optimization of the thin film preparation process and the improvement of the performance of optoelectronic materials.

[0076] Figure 2PL spectra of Example 1 (0.8 vol% BCOEA), Comparative Example 1 (0 vol% BCOEA), and Example 4 (1.6 vol% BCOEA). It reveals the significant effect of BCOEA additive concentration on the photoluminescence (PL) performance of the thin film. The test results show that introducing an appropriate amount of BCOEA into the thin film can significantly optimize its optical properties. Specifically, the thin film with 0.8 vol% BCOEA exhibits the most excellent PL performance, and its PL peak is precisely located at 461 nm. Compared with the thin film without BCOEA (PL peak at 467 nm), a significant blue shift is achieved, indicating that BCOEA as an additive can effectively adjust the energy band structure of the thin film and promote the conversion of energy to the short-wavelength direction. More remarkably, after adding BCOEA, the PL peak intensity of the thin film has increased significantly. Among them, the thin film containing 0.8 vol% BCOEA is the most prominent. Its PL intensity is not only significantly higher than that of the thin film without additives but also shows a slight advantage even compared with the thin film with a higher concentration (1.6 vol%) of BCOEA, indicating that at an appropriate concentration, BCOEA can maximize its role, promoting both the blue shift of the PL peak and significantly enhancing the luminescence intensity. Finally, 0.8 vol% BCOEA is confirmed to be the optimal addition amount, which can achieve a significant blue shift while ensuring the highest PL intensity of the thin film. This has profound guiding significance for the development of high-performance optoelectronic materials and devices.

[0077] Figure 3 Fitted curve graphs of transient fluorescence lifetime spectra for Example 1 (annealed for 3 min), Example 2 (annealed for 1 min), and Example 3 (annealed for 5 min). According to the experimental results, in Example 1 with an annealing time of 3 min, the fluorescence lifetime decay curve shows a more gentle downward trend compared to Examples with annealing times of 1 min and 5 min, that is, it decreases slightly more slowly. This phenomenon profoundly reveals the subtle effect of annealing time on the fluorescence lifetime of the material. Specifically, the thin film annealed for 3 min exhibits the longest fluorescence lifetime, indicating that an appropriate annealing treatment time can effectively promote the optimization and stability of the internal structure of the material, reduce non-radiative transition paths, thereby prolonging the relaxation time of excited-state electrons and enhancing the efficiency of fluorescence radiation.

[0078] Figure 4Transient fluorescence lifetime spectral fitting curves for Example 1 (0.8 vol% BCOEA), Comparative Example 1 (0 vol% BCOEA), and Example 4 (1.6 vol% BCOEA). According to the experimental results, the films with added BCOEA (whether 0.8 vol% or 1.6 vol%) showed significant advantages in terms of fluorescence lifetime. The downward trend of their decay curves was significantly gentler, indicating a much longer fluorescence lifetime than that of the films without added BCOEA. Specifically, the introduction of BCOEA effectively slowed down the relaxation process of excited-state electrons, prolonged the residence time of electrons in the excited state, and thus significantly increased the fluorescence lifetime of the films. It is worth noting that among the two films with BCOEA additives, the film with 0.8 vol% BCOEA showed a slightly better fluorescence lifetime, which was slightly longer than that of the film with 1.6 vol% BCOEA. This subtle difference further confirmed the importance of adding an appropriate amount of BCOEA for optimizing the fluorescence properties of the films. Too high or too low concentrations may not achieve the best results.

[0079] Figure 5 UV-visible absorption spectra of Example 1 (0.8 vol% BCOEA), Comparative Example 1 (0 vol% BCOEA), and Example 4 (1.6 vol% BCOEA). The experimental results clearly showed that at n = 2 phase (corresponding to a wavelength of 406 nm), all examples exhibited a distinct absorption peak, which reflected the inherent optical properties of the material at this energy level. However, when n = 3 phase, a remarkable difference emerged: compared with the films without added BCOEA, the films with added BCOEA (whether at a low concentration of 0.8 vol% or a high concentration of 1.6 vol%) showed a significant reduction in absorption intensity at n = 3 phase, and in some cases, it almost disappeared. This significant change deeply revealed the unique role of BCOEA additive in regulating the optical structure of the films, which could effectively inhibit the growth or development of the n = 3 phase. This inhibitory effect not only explained why the films containing BCOEA showed more blue-shifted emission peaks in the PL test but also further strengthened the close relationship between the emission characteristics of the films and their internal phase structure. Generally, the position of the emission peak of the film is dominated by the phase of its highest energy state, and the inhibition of the n = 3 phase directly led to the blue shift of the PL spectrum, that is, the emitted light shifted towards higher energy (shorter wavelength).

[0080] Figure 6PLQY test charts for Example 1 (annealing for 3 min), Example 2 (annealing for 1 min), and Example 3 (annealing for 5 min). The experimental results clearly reveal the significant effect of annealing time on the PLQY of the thin film. According to the experimental results, when the annealing time is 3 min, the PLQY of the thin film reaches an astonishing 93.4%. This high value indicates that under these conditions, the defects inside the thin film are effectively passivated, and the non-radiative transition pathways are significantly suppressed, thereby greatly enhancing the efficiency of radiative transitions and enabling more excited-state energy to be released in the form of photons. In contrast, the PLQY of the thin film annealed for 1 min is only 41.7%. This result reflects that too short an annealing time fails to fully promote the rearrangement of the internal structure of the thin film and the repair of defects, resulting in a relatively high proportion of non-radiative transitions and thus reducing the overall luminescence efficiency. For the thin film annealed for 5 min, although the PLQY increases to 61.6%, it still does not reach the optimal level. This indicates that too long an annealing time may trigger some adverse factors, such as excessive grain growth or the accumulation of interfacial stress, which to some extent offset the positive effects brought by annealing and limit the further improvement of PLQY.

[0081] Figure 7 PLQY test charts for Example 1 (0.8 vol% BCOEA), Comparative Example 1 (0 vol% BCOEA), and Example 4 (1.6 vol% BCOEA). This result not only reveals the significant role of BCOEA additive in enhancing the PLQY of the thin film but also further details the subtle differences in the influence of different additive concentrations on the performance. Specifically, when the addition amount of BCOEA is controlled at 0.8 vol%, the PLQY of the thin film is as high as 93.4%. This excellent performance fully demonstrates that the introduction of an appropriate amount of BCOEA can greatly optimize the internal structure of the thin film, reduce non-radiative recombination centers, and thus significantly improve the efficiency of radiative transitions, enabling more excited-state energy to be converted into photon radiation. However, when the addition amount of BCOEA increases to 1.6 vol%, although the PLQY of the thin film still remains at a relatively high level (47.3%), it shows an obvious decrease compared to the addition amount of 0.8 vol%. This phenomenon may imply that too high an additive concentration introduces new recombination paths or defects, partially offsetting the positive contribution of BCOEA to PLQY. It is particularly noteworthy that even in the two examples with different addition amounts of BCOEA, their PLQYs are much higher than that of the thin film without BCOEA (22.9%). This sharp contrast strongly illustrates the key role of BCOEA additive in enhancing the optical performance of the thin film. It can not only significantly improve PLQY but also reveals the possibility of further optimizing the performance by regulating the additive concentration.

[0082] The deep blue light-emitting quasi-2D perovskite thin film obtained in Comparative Example 2 is expected to have a decreased photoluminescence quantum yield (PLQY) because 2-hydroxyethyl N-butylcarbamate cannot effectively inhibit the formation of internal defects in the material. In addition, compared with Comparative Example 2, the design of the BCOEA molecule ingeniously incorporates longer chain length characteristics, which not only enriches the diversity of its chemical structure but also brings significant changes in physical properties. Specifically, the extended chain length enables the BCOEA molecule to form a more extensive and stable hydrogen bond network when interacting with organic ligands. This enhanced hydrogen bond interaction not only increases steric hindrance, effectively preventing intermolecular disordered aggregation, but also promotes the ordering of the internal structure of the material, achieving better phase segregation. The optimization of phase segregation directly promotes the concentrated transport of energy within the material, constructing an efficient "energy funnel" system that enables photo-generated carriers to be more smoothly directed to specific regions for recombination, thereby greatly improving the photoelectric conversion efficiency and device performance.

[0083] The above content has described the embodiments of the present invention in detail. However, the present invention is not limited to the above embodiments, and various changes can be made without departing from the spirit of the present invention within the knowledge scope of those of ordinary skill in the art. In addition, the embodiments of the present invention and the features in the embodiments can be combined with each other without conflict.

Claims

1. A composition for preparing a quasi-two-dimensional perovskite, characterized in that: The raw materials for preparing the composition include: cesium bromide, lead bromide, lead chloride, 2-acrylic acid-2-[[(butylamino)-carbonyl]oxy]ethyl ester, organic ligand, formamidine hydrobromide and small molecule inorganic bromide; The organic ligands include phenethylammonium bromide and fluorine-substituted compounds thereof and phenethylammonium chloride and fluorine-substituted compounds thereof; The formamidine hydrobromide includes at least one of formamidine hydrobromide, methyl ammonium bromide and propyl ammonium bromide; The small molecule inorganic bromide comprises at least one of lithium bromide, sodium bromide, zinc bromide and rubidium bromide; In the solution state, in the composition, Pb 2+ The concentration is 0.08~0.2mmol / ml.

2. The composition according to claim 1, characterized in that The phenethylammonium bromide and fluorine-substituted compounds thereof include at least one of phenethylammonium bromide, 2-fluorophenethylammonium bromide, 3-fluorophenethylammonium bromide and 4-fluorophenethylammonium bromide.

3. The composition according to claim 1, characterized in that The phenethylammonium chloride and fluorine-substituted compounds thereof include at least one of phenethylammonium chloride, 2-fluorophenethylammonium chloride, 3-fluorophenethylammonium chloride and 4-fluorophenethylammonium chloride.

4. A quasi-two-dimensional perovskite film, characterized in that: The quasi-two-dimensional perovskite film is prepared from the composition according to any one of claims 1 to 3.

5. A method for preparing the quasi-two-dimensional perovskite film according to claim 4, characterized in that: include: Applying a solution of a quasi-two-dimensional perovskite composition onto a substrate to obtain a primary film, and then heating and annealing to obtain the quasi-two-dimensional perovskite film; The annealing temperature is 50-90°C; The annealing time is 1 to 3 minutes.

6. A blue perovskite light-emitting diode, characterized in that: The blue light perovskite light-emitting diode is prepared from the quasi-two-dimensional perovskite film described in claim 5.

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