A quasi-two-dimensional red light perovskite LED device and a preparation method thereof

Abstract

The application discloses a quasi-two-dimensional red light perovskite LED device and a preparation method thereof, and belongs to the technical field of light emitting diodes, wherein the preparation method comprises the following steps: depositing a PEDOT:PSS aqueous solution on a substrate surface by a spin coating method, and performing a first annealing treatment; mixing TFB and PVK in a chlorobenzene solution, and depositing the mixture on the substrate surface after the first annealing treatment by a spin coating method, and performing a second annealing treatment; depositing a calcium lignosulfonate solution on the substrate surface after the second annealing treatment by a spin coating method; dissolving lead iodide, cesium iodide, zinc iodide, 3,3-diphenylpropylamine iodine, 1-naphthalene methylamine iodine and phenylethylamine iodine in an N,N-dimethylformamide solution to obtain a perovskite precursor solution; dropping the perovskite precursor solution on the substrate surface after the above treatment to prepare a thin film, and performing a third annealing treatment on the thin film; and evaporating an electron transport layer and a cathode electrode on the thin film to obtain the quasi-two-dimensional red light perovskite LED device. The quasi-two-dimensional red light perovskite LED device has a small turn-on voltage, high brightness and high external quantum efficiency.

Description

Technical Field

[0001] This invention relates to the field of light-emitting diode technology, specifically to a quasi-two-dimensional red perovskite LED device and its fabrication method. Background Technology

[0002] The unique properties of perovskite materials, situated between inorganic semiconductors and organic materials, endow them with excellent optoelectronic performance, particularly promising for the fabrication of high-efficiency light-emitting diodes (LEDs). In recent years, with the deepening of related research, attention has gradually increased towards quasi-two-dimensional perovskites, characterized by high fluorescence quantum efficiency and narrow half-maximum width at half-maximum (HWHM). Due to their high photoluminescence quantum yield, tunable optical bandgap, excellent color purity, and low-cost solution processability, they hold broad prospects in LED and display applications. Quasi-two-dimensional perovskite LEDs are still in their early stages of development and face many difficulties and challenges. Currently, the optoelectronic properties of LEDs using perovskite materials as the emitting layer are still far lower than those of state-of-the-art organic LEDs. This is mainly due to the uneven phase distribution of the perovskite film, resulting in excessively low energy transfer efficiency, and insufficient wettability between the solution and the substrate interface, leading to poor film crystal quality. Both of these factors contribute to the poor optoelectronic performance of perovskite LED devices.

[0003] Quasi-two-dimensional red-luminescent perovskites are generally obtained by adding an excess of organic cations to iodine-based three-dimensional perovskites. During growth, by adjusting the content of organic cations in the precursor, quasi-two-dimensional red-luminescent perovskites will generate layered perovskite phases containing different numbers of lead halide octahedral layers. Among these quasi-two-dimensional perovskite phases, the n-phase is the quasi-two-dimensional perovskite phase with n layers of lead halide octahedrons. The commonly referred to small n-phases are n=1 and 2 phases, and large n-phases are n=3 and 4 phases. The luminescent phase is the phase with the largest n-value among the large n-phases. The small n-phase in quasi-two-dimensional perovskites, with its numerous defects, leads to severe nonradiative recombination. Its wide band gap also hinders carrier injection and transport. Furthermore, an excessive amount of small n-phase results in incomplete energy transfer during energy transfer, leading to low luminescence performance. However, during the nucleation process of quasi-two-dimensional perovskite growth, a high formation energy for the small n-phase makes it easier to form and results in a higher content, while the content of the large n-phase is relatively low. Therefore, the distribution of the quasi-two-dimensional red-luminescent perovskite phase is unfavorable for luminescence. Effective management of the distribution of quasi-two-dimensional red perovskite phases, i.e., suppressing the formation of small n-phase and promoting its transformation into large n-phase, is one of the effective means to improve the performance of quasi-two-dimensional red perovskite LEDs. Furthermore, in bottom-emitting upright LED device structures consisting of an anode, hole transport layer, light-emitting layer, electron transport layer, and cathode, the quality of the light-emitting layer, i.e., the perovskite thin film, is mainly affected by the material of the upper transport layer. Currently, commonly used transport layer materials are mainly organic polymers with certain carrier mobility, such as PMMA (polymethyl methacrylate), PVK (poly(9-vinylcarbazole)), TFB (poly[(9,9-di-n-octylfluorenyl-2,7-diyl)-alt-(4,4'-(N-(4-n-butyl)phenyl)-diphenylamine)]), PTAA (poly[bis(4-phenyl)(2,4,6-trimethylphenyl)amine]), and POLY-TPD (poly[bis(4-phenyl)(4-butylphenyl)amine]). However, their strong hydrophobicity often leads to poor crystallinity of the perovskite thin film spin-coated on it, which in turn leads to more defects and non-radiative recombination, thus damaging the photoelectric performance of the perovskite LED device.

[0004] There are many reasons limiting the photoelectric performance of quasi-two-dimensional red perovskite light-emitting diodes (LEDs), with unreasonable phase distribution and poor film quality being two of the most important factors. First, in quasi-two-dimensional perovskites, the small n-phase (n≤2) has a low formation energy and is therefore easily formed in large quantities. However, the small n-phase, with its strong electron-phonon coupling, is dominated by nonradiative recombination, which is not conducive to light emission. Furthermore, an excessive amount of small n-phase makes it difficult for excitons to match with the large n-phase nearby, thus hindering the energy transfer process. Insufficient energy transfer from the small n-phase to the large n-phase often leads to lower device performance, especially lower EQE (external quantum efficiency). Second, the film quality of perovskite films in upright device structures is mainly affected by the material of the upper transport layer. Currently, commonly used transport layer materials are mainly organic polymers, but their strong hydrophobicity often leads to poor crystallinity of the perovskite film, resulting in more defects and nonradiative recombination.

[0005] Therefore, optimizing the phase distribution and improving the quality of quasi-two-dimensional perovskite films is of great significance for fabricating high-performance perovskite optoelectronic devices. In existing technologies, phase distribution is generally adjusted by doping or adding additives. However, this method significantly impacts the quantum confinement effect of quasi-two-dimensional perovskites, leading to severe emission deviations. Summary of the Invention

[0006] The purpose of this invention is to provide a method for fabricating a quasi-two-dimensional red perovskite LED device to solve the problems mentioned in the background art.

[0007] To achieve the above objectives, the embodiments of the present invention provide the following technical solutions:

[0008] A method for fabricating a quasi-two-dimensional red perovskite LED device includes the following steps:

[0009] The PEDOT:PSS aqueous solution was deposited onto the substrate surface etched with the anode electrode by spin coating and then subjected to a first-step annealing treatment.

[0010] TFB and PVK were mixed and dissolved in a chlorobenzene solution and deposited onto the substrate surface after the first annealing treatment by spin coating, followed by a second annealing treatment.

[0011] The calcium lignosulfonate solution was deposited onto the substrate surface after the second annealing process by spin coating.

[0012] Lead iodide, cesium iodide, zinc iodide, 3,3-diphenylpropylamine iodide, 1-naphthylamine iodide and phenethylamine iodide were dissolved in N,N-dimethylformamide solution to obtain perovskite precursor solution;

[0013] The perovskite precursor solution was dropped onto the substrate surface after the above steps, and a thin film was prepared by spin coating. The thin film was then subjected to a third annealing treatment.

[0014] An electron transport layer and a cathode electrode are deposited on the above-mentioned thin film to obtain the quasi-two-dimensional red perovskite LED device.

[0015] Preferably, the anode electrode is indium tin oxide, and the substrate is glass sputtered with indium tin oxide.

[0016] Preferably, the temperature of the first annealing step is 145-155℃; the temperature of the second annealing step is 155-165℃; and the temperature of the third annealing step is 65-75℃.

[0017] Preferably, the concentration of the PEDOT:PSS aqueous solution is 1.3-1.7 wt%.

[0018] Preferably, the mass ratio of TFB to PVK is 1:(4-6).

[0019] Preferably, the calcium lignosulfonate solution is an aqueous solution of calcium lignosulfonate with a concentration of 8-12 mg / mL.

[0020] Preferably, the molar ratio of lead iodide, cesium iodide, zinc iodide, 3,3-diphenylpropylamine iodide, 1-naphthylamine iodide and phenethylamine iodide is (8-10):(4-6):(0.5-1.5):(0.5-1.5):(3-5):(4-6).

[0021] Preferably, the vapor-deposited electron transport layer is 2,4,6-tris[3-(diphenylphosphino)phenyl]-1,3,5-triazole.

[0022] Preferably, the cathode electrode is lithium fluoride and aluminum.

[0023] Another object of the present invention is to provide a quasi-two-dimensional red perovskite LED device prepared by the above-described preparation method.

[0024] The method for fabricating quasi-two-dimensional red perovskite LED devices provided by this invention achieves excellent phase modulation effects through interface modification strategies. While adjusting the phase distribution and enhancing the energy transfer capability of the quasi-two-dimensional perovskite, the highly hydrophilic sulfonate groups improve the wettability of the perovskite precursor solution and the bottom interface, thereby enhancing the crystallinity and film coverage of the perovskite film. Under the dual-functional effect of the interface modification strategy, the defect state density of the film is reduced, non-radiative recombination is decreased, and the energy funnel effect of the quasi-two-dimensional perovskite is promoted, thus improving the photoelectric performance of the device.

[0025] The method for fabricating quasi-two-dimensional red perovskite LED devices provided by this invention is simple to operate, time-saving, highly efficient, and extremely low in cost. The calcium lignosulfonate deposition layer used as an interface modification in this invention can significantly adjust the phase distribution of the quasi-two-dimensional perovskite, enhance the photoelectric performance of the device, and improve the quality of the energy level thin film. The quasi-two-dimensional red perovskite LED devices prepared by this invention have low turn-on voltage, high brightness, and high external quantum efficiency (EQE).

[0026] In addition, the calcium lignosulfonate used in this invention is an inexpensive and pollution-free green material with extremely low production costs. Furthermore, its main raw material, lignin, is the second largest biomass resource after cellulose in terms of reserves, and it is also the only renewable aromatic compound resource in nature. The extremely low raw material and production costs are extremely advantageous for replacing expensive additives, applying it to the field of perovskite research, and even realizing industrialization. Attached Figure Description

[0027] Figure 1 The external quantum efficiency-current density characteristic curves of the LED devices prepared in Example 1 and Comparative Example 1 are shown.

[0028] Figure 2 The current density-voltage-brightness characteristic curves of the LED devices prepared in Example 1 and Comparative Example 1 are shown.

[0029] Figure 3 The electroluminescence spectra of the LED devices prepared in Example 1 and Comparative Example 1 are shown.

[0030] Figure 4 The absorption spectra of the LED devices prepared in Example 1 and Comparative Example 1 are shown.

[0031] Figure 5 The photoluminescence spectra of the LED devices prepared in Example 1 and Comparative Example 1 are shown.

[0032] Figure 6 This is a comparison chart of the water contact angle tests of the LED devices prepared in Example 1 and Comparative Example 1.

[0033] Figure 7 Atomic force microscope (AFM) images of the LED devices prepared in Example 1 and Comparative Example 1. Detailed Implementation

[0034] The technical solutions of the present invention will be clearly and completely described below with reference to the embodiments of the present invention. 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 of ordinary skill in the art without creative effort are within the scope of protection of the present invention.

[0035] To address the technical problems raised in the background, this invention employs an interface modification strategy: introducing a layer of calcium lignin sulfonate molecules between the hole transport layer and the perovskite layer to manage the phase distribution of the perovskite film. The sulfonate groups in this substance bind with the long organic chains in the perovskite solution, inhibiting the formation and accumulation of the small n-phase (i.e., n=2). Specifically, the calcium lignin sulfonate molecules deposited between the hole transport layer and the perovskite layer can diffuse with the organic cations (3,3-diphenylpropylamine cation and 1-naphthylamine cation) in the perovskite precursor at the bottom interface. The combination of lignin(n) and calcium sulfonate reduces their participation in the crystallization process of perovskite, thereby inhibiting the growth of the small n phase in the quasi-two-dimensional perovskite, increasing the proportion of the large n phase, optimizing the phase distribution of the quasi-two-dimensional perovskite, and promoting its energy transfer process. In addition, the sulfonate groups in the deposited calcium lignin sulfonate molecules have strong hydrophilicity, which can greatly improve the wettability of the perovskite precursor solution and the substrate interface, improve the crystallization quality of the perovskite film, reduce roughness, reduce defect state density, thereby inhibiting non-radiative recombination and improving the performance of quasi-two-dimensional red perovskite LED devices.

[0036] Example 1: This example provides a method for fabricating a quasi-two-dimensional red perovskite LED device with calcium lignosulfonate as an interface modifier, which includes the following steps:

[0037] S1. The conductive glass substrate with the etched anode electrode ITO (indium tin oxide) is repeatedly cleaned with deionized water, ethanol and dichloromethane, and then cleaned with an ultraviolet ozone generator for 15 minutes.

[0038] S2. A 1.5 wt% aqueous solution of poly(3,4-ethylenedioxythiophene)-polystyrene sulfonic acid (PEDOT:PSS) is deposited onto the substrate surface treated in step S1 by spin coating and subjected to a first-step annealing treatment at 150°C for 20 minutes.

[0039] S3. Mix 0.5 mg of poly[(9,9-di-n-octylfluorenyl-2,7-diyl)-alt-(4,4'-(N-(4-n-butyl)phenyl)-diphenylamine)] (TFB) and 2.5 mg of poly(9-vinylcarbazole) (PVK) and dissolve them in 1 mL of chlorobenzene solution. Then, spin-coat the mixture onto the substrate surface treated in step S2 above and perform a second annealing treatment at 160°C for 20 minutes.

[0040] S4. Dissolve 10 mg of calcium lignosulfonate in 1 mL of deionized water to obtain a calcium lignosulfonate solution; then deposit the calcium lignosulfonate solution onto the substrate surface treated in step S3 above by spin coating.

[0041] S5. Dissolve 0.09 mmol of lead iodide, 0.05 mmol of cesium iodide, 0.01 mmol of zinc iodide, 0.01 mmol of 3,3-diphenylpropylamine iodide, 0.04 mmol of 1-naphthylamino iodide and 0.05 mmol of phenethylamine iodide in 1 mL of N,N-dimethylformamide solution to obtain perovskite precursor solution;

[0042] S6. The above perovskite precursor solution is dropped onto the substrate surface treated in step S4 above, and a thin film is prepared by spin coating. Then the thin film is placed on a heating table and heated to 70°C for the third annealing treatment for 10 minutes.

[0043] S7. Place the above thin film in a vapor deposition apparatus to vapor deposit a 2,4,6-tris[3-(diphenylphosphino)phenyl]-1,3,5-triazole (PO-T2T) electron transport layer (thickness of 35 nm) and a cathode electrode (composed of lithium fluoride and aluminum, with thicknesses of 1 nm and 100 nm, respectively), to obtain a quasi-two-dimensional red perovskite LED device.

[0044] Example 2: This example provides a method for fabricating a quasi-two-dimensional red perovskite LED device, which includes the following steps:

[0045] S1. The conductive glass substrate with the etched anode electrode ITO was repeatedly cleaned with deionized water, ethanol and dichloromethane, and then cleaned with ultraviolet ozone for 15 minutes.

[0046] S2. A 1.3 wt% PEDOT:PSS aqueous solution was deposited onto the substrate surface treated in step S1 by spin coating and subjected to a first-step annealing treatment at 145°C for 20 minutes.

[0047] S3. Mix 0.5 mg of TFB and 2 mg of PVK and dissolve them in 1 mL of chlorobenzene solution. Then, deposit the mixture onto the substrate surface treated in step S2 by spin coating and perform a second annealing treatment at 155°C for 20 minutes.

[0048] S4. Dissolve 8 mg of calcium lignosulfonate in 1 mL of deionized water to obtain a calcium lignosulfonate solution; then deposit the calcium lignosulfonate solution onto the substrate surface treated in step S3 above by spin coating.

[0049] S5. Dissolve 0.08 mmol of lead iodide, 0.04 mmol of cesium iodide, 0.005 mmol of zinc iodide, 0.005 mmol of 3,3-diphenylpropylamine iodide, 0.03 mmol of 1-naphthylamino iodide and 0.04 mmol of phenethylamine iodide in 1 mL of N,N-dimethylformamide solution to obtain perovskite precursor solution;

[0050] S6. The above perovskite precursor solution is dropped onto the substrate surface treated in step S4 above, and a thin film is prepared by spin coating. Then the thin film is placed on a heating table and heated to 65°C for the third annealing treatment for 10 minutes.

[0051] S7. Place the above thin film in a vapor deposition apparatus to vapor deposit a PO-T2T electron transport layer (thickness of 35nm) and a cathode electrode (composed of lithium fluoride and aluminum, with thicknesses of 1nm and 100nm, respectively), to obtain a quasi-two-dimensional red perovskite LED device.

[0052] Example 3: This example provides a method for fabricating a quasi-two-dimensional red perovskite LED device, which includes the following steps:

[0053] S1. The conductive glass substrate with the etched anode electrode ITO was repeatedly cleaned with deionized water, ethanol and dichloromethane, and then cleaned with ultraviolet ozone for 15 minutes.

[0054] S2. A 1.7 wt% PEDOT:PSS aqueous solution was deposited onto the substrate surface treated in step S1 by spin coating and subjected to a first-step annealing treatment at 155°C for 20 minutes.

[0055] S3. Mix 0.5 mg of TFB and 3 mg of PVK and dissolve them in 1 mL of chlorobenzene solution. Then, deposit the mixture onto the substrate surface treated in step S2 by spin coating and perform a second annealing treatment at 165°C for 20 minutes.

[0056] S4. Dissolve 12 mg of calcium lignosulfonate in 1 mL of deionized water to obtain a calcium lignosulfonate solution; then deposit the calcium lignosulfonate solution onto the substrate surface treated in step S3 above by spin coating.

[0057] S5. Dissolve 0.1 mmol of lead iodide, 0.06 mmol of cesium iodide, 0.015 mmol of zinc iodide, 0.015 mmol of 3,3-diphenylpropylamine iodide, 0.05 mmol of 1-naphthylamino iodide and 0.06 mmol of phenethylamine iodide in 1 mL of N,N-dimethylformamide solution to obtain perovskite precursor solution;

[0058] S6. The above perovskite precursor solution is dropped onto the substrate surface treated in step S4 above, and a thin film is prepared by spin coating. Then the thin film is placed on a heating table and heated to 75°C for the third annealing treatment for 10 minutes.

[0059] S7. Place the above thin film in a vapor deposition apparatus to vapor deposit a PO-T2T electron transport layer (thickness of 35nm) and a cathode electrode (composed of lithium fluoride and aluminum, with thicknesses of 1nm and 100nm, respectively), to obtain a quasi-two-dimensional red perovskite LED device.

[0060] Example 4: This example provides a method for fabricating a quasi-two-dimensional red perovskite LED device, which includes the following steps:

[0061] S1. The conductive glass substrate with the etched anode electrode ITO was repeatedly cleaned with deionized water, ethanol and dichloromethane, and then cleaned with ultraviolet ozone for 15 minutes.

[0062] S2. A 1.4 wt% PEDOT:PSS aqueous solution was deposited onto the substrate surface treated in step S1 by spin coating and subjected to a first-step annealing treatment at 148°C for 20 minutes.

[0063] S3. Mix 0.5 mg of TFB and 2.6 mg of PVK in 1 mL of chlorobenzene solution and deposit it onto the substrate surface treated in step S2 by spin coating. Then, perform a second annealing treatment at 158°C for 20 minutes.

[0064] S4. Dissolve 9 mg of calcium lignosulfonate in 1 mL of deionized water to obtain a calcium lignosulfonate solution; then deposit the calcium lignosulfonate solution onto the substrate surface treated in step S3 above by spin coating.

[0065] S5. Dissolve 0.09 mmol of lead iodide, 0.04 mmol of cesium iodide, 0.012 mmol of zinc iodide, 0.008 mmol of 3,3-diphenylpropylamine iodide, 0.05 mmol of 1-naphthylamino iodide and 0.04 mmol of phenethylamine iodide in 1 mL of N,N-dimethylformamide solution to obtain perovskite precursor solution;

[0066] S6. The above perovskite precursor solution is dropped onto the substrate surface treated in step S4 above, and a thin film is prepared by spin coating. Then the thin film is placed on a heating table and heated to 68°C for the third annealing treatment for 10 minutes.

[0067] S7. Place the above thin film in a vapor deposition apparatus to vapor deposit a PO-T2T electron transport layer (thickness of 35nm) and a cathode electrode (composed of lithium fluoride and aluminum, with thicknesses of 1nm and 100nm, respectively), to obtain a quasi-two-dimensional red perovskite LED device.

[0068] Example 5: This example provides a method for fabricating a quasi-two-dimensional red perovskite LED device, which includes the following steps:

[0069] S1. The conductive glass substrate with the etched anode electrode ITO was repeatedly cleaned with deionized water, ethanol and dichloromethane, and then cleaned with ultraviolet ozone for 15 minutes.

[0070] S2. A 1.6 wt% PEDOT:PSS aqueous solution was deposited onto the substrate surface treated in step S1 by spin coating and subjected to a first-step annealing treatment at 152°C for 20 minutes.

[0071] S3. Mix 0.5 mg of TFB and 2.8 mg of PVK in 1 mL of chlorobenzene solution and deposit it onto the substrate surface treated in step S2 by spin coating. Then, perform a second annealing treatment at 162°C for 20 minutes.

[0072] S4. Dissolve 11 mg of calcium lignosulfonate in 1 mL of deionized water to obtain a calcium lignosulfonate solution; then deposit the calcium lignosulfonate solution onto the substrate surface treated in step S3 above by spin coating.

[0073] S5. Dissolve 0.09 mmol of lead iodide, 0.06 mmol of cesium iodide, 0.01 mmol of zinc iodide, 0.01 mmol of 3,3-diphenylpropylamine iodide, 0.05 mmol of 1-naphthylamino iodide and 0.04 mmol of phenethylamine iodide in 1 mL of N,N-dimethylformamide solution to obtain perovskite precursor solution;

[0074] S6. The above perovskite precursor solution is dropped onto the substrate surface treated in step S4 above, and a thin film is prepared by spin coating. Then the thin film is placed on a heating table and heated to 72°C for the third annealing treatment for 10 minutes.

[0075] S7. Place the above thin film in a vapor deposition apparatus to vapor deposit a PO-T2T electron transport layer (thickness of 35nm) and a cathode electrode (composed of lithium fluoride and aluminum, with thicknesses of 1nm and 100nm, respectively), to obtain a quasi-two-dimensional red perovskite LED device.

[0076] Comparative Example 1: This comparative example provides a method for fabricating a quasi-two-dimensional red perovskite LED device without calcium lignin sulfonate as an interface modifier, which includes the following steps:

[0077] S1. The conductive glass substrate with the etched anode electrode ITO (indium tin oxide) is repeatedly cleaned with deionized water, ethanol and dichloromethane, and then cleaned with an ultraviolet ozone generator for 15 minutes.

[0078] S2. A 1.5 wt% aqueous solution of poly(3,4-ethylenedioxythiophene)-polystyrene sulfonic acid (PEDOT:PSS) is deposited onto the substrate surface treated in step S1 by spin coating and subjected to a first-step annealing treatment at 150°C for 20 minutes.

[0079] S3. Mix 0.5 mg of poly[(9,9-di-n-octylfluorenyl-2,7-diyl)-alt-(4,4'-(N-(4-n-butyl)phenyl)-diphenylamine)] (TFB) and 2.5 mg of poly(9-vinylcarbazole) (PVK) and dissolve them in 1 mL of chlorobenzene solution. Then, spin-coat the mixture onto the substrate surface treated in step S2 above and perform a second annealing treatment at 160°C for 20 minutes.

[0080] S4. Dissolve 0.09 mmol of lead iodide, 0.05 mmol of cesium iodide, 0.01 mmol of zinc iodide, 0.01 mmol of 3,3-diphenylpropylamine iodide, 0.04 mmol of 1-naphthylamino iodide and 0.05 mmol of phenethylamine iodide in 1 mL of N,N-dimethylformamide solution to obtain perovskite precursor solution;

[0081] S5. The above perovskite precursor solution is dropped onto the substrate surface treated in step S3 above, and a thin film is prepared by spin coating. Then the thin film is placed on a heating table and heated to 70°C for the third annealing treatment for 10 minutes.

[0082] S6. Place the above thin film in a vapor deposition apparatus to deposit a 2,4,6-tris[3-(diphenylphosphino)phenyl]-1,3,5-triazole (PO-T2T) electron transport layer (thickness of 35 nm) and a cathode electrode (composed of lithium fluoride and aluminum, with thicknesses of 1 nm and 100 nm, respectively), to obtain a quasi-two-dimensional red perovskite LED device.

[0083] Performance Testing: The LED device without calcium lignosulfonate interface modification prepared in Comparative Example 1 (labeled "Control" in the attached figure) and the LED device with calcium lignosulfonate interface modification prepared in Example 1 (labeled "Target" in the attached figure) were compared in various performance aspects. The results are as follows: Figures 1-7 As shown. Specifically, as... Figure 1 As shown, the LED device with interface modification prepared in Example 1 (with a light-emitting area of ​​1 cm²) was found to be effective. 2 Its core performance indicator, external quantum efficiency (EQE), is significantly improved; for example... Figure 2 As shown, the modified LED device prepared in Example 1 exhibits lower current density and a greater increase in luminous intensity with increasing voltage under the same voltage, indicating a significant improvement in its photoelectric performance; Figure 3As shown, after modification, under the same voltage, the LED device prepared in Example 1 exhibits significantly stronger EL; as Figure 4 As shown, the modified perovskite film exhibits a decrease in the absorption peak representing the small n-phase and a strengthening of the absorption peak representing the large n-phase, indicating that calcium lignosulfonate can effectively inhibit the growth of the small n-phase and promote the formation of the large n-phase; Figure 5 As shown, after modification, the emission of the small n-phase decreases, and the emission peak is slightly red-shifted (due to the increased number of large n-phase phases). This is consistent with... Figure 4 The phenomena demonstrated are consistent; such as Figure 6 As shown, the water contact angle at the modified interface is significantly reduced, indicating that calcium lignosulfonate can effectively improve interfacial wettability; Figure 7 As shown, the roughness of the modified perovskite film is significantly reduced, indicating that it can effectively improve the quality of the perovskite film.

[0084] In summary, the embodiments of this invention employ an interface modification strategy. Calcium lignosulfonate is deposited beneath the luminescent layer via spin coating, forming a uniformly textured, wet film. Through diffusion, the wet film diffuses into the quasi-two-dimensional perovskite within the luminescent layer, influencing its crystal growth process. This allows for the control of the phase distribution of the quasi-two-dimensional perovskite film and avoids severe emission peak shifts. Furthermore, the interface modification strategy, while controlling the phase distribution, also improves the wettability between the perovskite layer and the underlying interface, thereby enhancing the film's crystallinity. This is something that doping or additive methods cannot achieve. This invention achieves a dual-functional optimization effect with a simple interface modification strategy.

[0085] Based on the above-described preferred embodiments of the present invention, and through the foregoing description, those skilled in the art can make various changes and modifications without departing from the inventive concept. The technical scope of this invention is not limited to the contents of the specification.

Claims

1. A method for fabricating a quasi-two-dimensional red perovskite LED device, characterized in that, Includes the following steps: The PEDOT:PSS aqueous solution was deposited onto the substrate surface etched with the anode electrode by spin coating and then subjected to a first-step annealing treatment. Poly[(9,9-di-n-octylfluorenyl-2,7-diyl)-alt-(4,4'-(N-(4-n-butyl)phenyl)-diphenylamine)]TFB and poly(9-vinylcarbazole)PVK were mixed and dissolved in chlorobenzene solution, and deposited onto the substrate surface after the first annealing treatment by spin coating, followed by the second annealing treatment; A calcium lignosulfonate solution is deposited onto the substrate surface after the second annealing treatment by spin coating; the calcium lignosulfonate solution is an aqueous solution of calcium lignosulfonate with a concentration of 8-12 mg / mL. Lead iodide, cesium iodide, zinc iodide, 3,3-diphenylpropylamine iodide, 1-naphthylamine iodide and phenethylamine iodide were dissolved in N,N-dimethylformamide solution to obtain perovskite precursor solution; The perovskite precursor solution was dropped onto the substrate surface after the above steps, and a thin film was prepared by spin coating. The thin film was then subjected to a third annealing treatment. An electron transport layer and a cathode electrode are deposited on the above-mentioned thin film to obtain the quasi-two-dimensional red perovskite LED device.

2. The method for fabricating a quasi-two-dimensional red perovskite LED device according to claim 1, characterized in that, The anode electrode is indium tin oxide, and the substrate is glass sputtered with indium tin oxide.

3. The method for fabricating a quasi-two-dimensional red perovskite LED device according to claim 1, characterized in that, The first annealing process is carried out at a temperature of 145-155℃; the second annealing process is carried out at a temperature of 155-165℃; and the third annealing process is carried out at a temperature of 65-75℃.

4. The method for fabricating a quasi-two-dimensional red perovskite LED device according to claim 1, characterized in that, The concentration of the PEDOT:PSS aqueous solution is 1.3-1.7 wt%.

5. The method for fabricating a quasi-two-dimensional red perovskite LED device according to claim 1, characterized in that, The mass ratio of TFB to PVK is 1:(4-6).

6. The method for fabricating a quasi-two-dimensional red perovskite LED device according to claim 1, characterized in that, The molar ratio of lead iodide, cesium iodide, zinc iodide, 3,3-diphenylpropylamine iodide, 1-naphthylamine iodide and phenethylamine iodide is (8-10):(4-6):(0.5-1.5):(0.5-1.5):(3-5):(4-6).

7. The method for fabricating a quasi-two-dimensional red perovskite LED device according to claim 1, characterized in that, The vapor-deposited electron transport layer is 2,4,6-tris[3-(diphenylphosphoxy)phenyl]-1,3,5-triazole.

8. The method for fabricating a quasi-two-dimensional red perovskite LED device according to claim 1, characterized in that, The cathode electrode is composed of lithium fluoride and aluminum.

9. A quasi-two-dimensional red perovskite LED device prepared by any one of claims 1-8.

Images