Host-guest compound passivated blue-light perovskite light-emitting diode and full-solution preparation method thereof

Abstract

The invention provides a host-guest compound passivated blue-light perovskite light-emitting diode and an all-solution preparation method thereof, and belongs to the technical field of perovskite light-emitting diodes. In the process of preparing the blue-light perovskite light-emitting diode by an all-solution method, various crown ethers and p-fluorophenylethylamine bromide or p-fluorophenylethylamine chloride form a host-guest compound, the host-guest compound is doped into an electron transport layer precursor solution, and then the electron transport layer precursor solution is coated on a perovskite layer, so that the blue-light perovskite light-emitting diode is prepared. In-situ passivation of defects of the perovskite light-emitting layer and preparation of the electron transport layer are realized in one step, and the problems of increase of defect states of the perovskite light-emitting layer, aggravation of non-radiative recombination and the like caused by deposition of the electron transport layer in a traditional full-solution preparation method are effectively solved. The long-term operation stability of the device and the quantum yield of electroluminescence are effectively improved, and the method has important significance for promoting large-scale application of all-solution method preparation of the perovskite light-emitting diode.

Description

Technical Field

[0001] This invention specifically relates to a host-guest composite passivated blue perovskite light-emitting diode and its whole solution preparation method, belonging to the field of perovskite light-emitting diode technology. Background Technology

[0002] Metal halide perovskites possess significant advantages such as tunable spectrum, high color saturation, low cost, and ease of fabrication, making them a promising luminescent material for future lighting and display applications. Compared to organic light-emitting diodes (OLEDs), perovskite light-emitting diodes (PeLEDs) based on metal halide perovskites exhibit narrow emission spectrum width at half maximum (FWHM), high color purity, and a wide color gamut, making them more ideal light-emitting elements.

[0003] From a device structure perspective, PeLEDs mainly consist of functional layers such as electrodes, hole transport layer (HTL), perovskite emitting layer, and electron transport layer (ETL). Depending on the composition of the perovskite emitting layer, PeLEDs can emit light in various colors, including red, green, and blue. However, compared to green and red PeLEDs, blue PeLEDs have a wider bandgap and more deep-level defects, resulting in poorer stability and slow development. The emitting layer material for blue PeLEDs is typically a bromine-chlorine mixed halogen perovskite (such as CsPbBr). x Cl (3-x) Due to the significant difference in radius between the two halide ions, the perovskite emitting layer is prone to ion migration and halogen phase separation during film formation, leading to a redshift in the emission peak and a decrease in color purity, making it difficult to stably achieve pure blue light emission. Furthermore, in current PeLED manufacturing processes, the electron transport layer above the perovskite emitting layer is almost always deposited using high-vacuum evaporation. This process is not only time-consuming and costly, but also suffers from limited device area and low yield, further hindering the industrialization of blue PeLEDs.

[0004] Compared to vacuum deposition technology, the all-solution method for fabricating perovskite light-emitting diodes (LEDs) by depositing the electron transport layer using solution spin coating has gained increasing attention due to its significant advantages, including room-temperature fabrication, low equipment cost, short fabrication cycle, and high production efficiency. Currently, the efficiency of perovskite LED devices fabricated using the all-solution method has approached 20% of that achieved by vacuum-deposited devices. However, in the all-solution fabrication process, as the electron transport layer solvent spins and washes off the surface of the perovskite emitting layer, organic ligands and additives on the surface and grain boundaries of the perovskite emitting layer inevitably erode, leading to the formation of a large number of defect states. This ultimately results in increased nonradiative recombination of charge carriers on the device and a decrease in device efficiency. Moreover, specifically for blue light-emitting diodes, the inherent instability of bromochloro-based blue light perovskite materials is a limitation. The all-solution fabrication method further exacerbates the inherent phase separation and emission peak redshift problems, making it difficult to achieve a breakthrough in the stability and electroluminescence quantum yield of blue light devices fabricated by the all-solution method. This severely restricts the industrial application of the all-solution fabrication method in the fabrication of blue PeLEDs. Summary of the Invention

[0005] To address existing problems, this invention provides a host-guest composite passivated blue perovskite light-emitting diode and its all-solution preparation method. In the all-solution preparation process of blue perovskite light-emitting diodes, this invention incorporates a host-guest composite into an electron transport layer precursor solution, which is then coated onto the perovskite layer. This achieves in-situ passivation of defects in the perovskite light-emitting layer and preparation of the electron transport layer in one step, effectively overcoming the problems of increased defect states and intensified non-radiative recombination in the perovskite light-emitting layer caused by electron transport layer deposition in traditional all-solution preparation methods. This significantly improves the long-term operational stability of the device and the external quantum efficiency of electroluminescence, and is of great significance for promoting the large-scale application of all-solution preparation of blue perovskite light-emitting diodes.

[0006] The technical solution of the present invention is as follows: This invention provides a full-solution preparation method for a host-guest composite passivated perovskite light-emitting diode (LED), wherein the perovskite light-emitting layer material of the LED is bromochloro-based blue light perovskite. The full-solution preparation method specifically includes the following steps: First, prepare precursor solutions for the hole transport layer, the perovskite light-emitting layer, and the electron transport layer respectively. Then, coat and stack the corresponding precursor solutions sequentially from bottom to top on the upper surface of the anode substrate by spin coating to form the corresponding hole transport layer, the perovskite light-emitting layer, and the electron transport layer. Finally, deposit the cathode electrode to obtain the perovskite LED.

[0007] In the preparation process of the all-solution method, this invention addresses the defect characteristics of bromochloro-based blue light perovskite by introducing a host-guest complex to passivate it, and finally obtains a perovskite light-emitting diode with host-guest complex passivation; the host-guest complex is composed of a crown ether as the host and p-fluorophenylethylamine bromide (p-FPEABr) or p-fluorophenylethylamine chloride (p-FPEACl) as the guest through self-assembly.

[0008] Furthermore, this invention incorporates the host-guest complex into the electron transport layer precursor solution, and then spin-coates the electron transport layer onto the perovskite luminescent layer to simultaneously passivate the perovskite luminescent layer. Specifically, the process includes the following steps: S1. P-FPEAX (X is Cl) - or Br - p-FPEAX and crown ether are added to an organic solvent containing electron transport layer material and dissolved completely. During the dissolution process, p-FPEAX and crown ether self-assemble in the organic solvent to form a host-guest complex, thereby obtaining an electron transport layer precursor solution. S2. Spin-coat the electron transport layer precursor solution onto the perovskite luminescent layer to passivate the perovskite luminescent layer. After spin-coating, the electron transport layer is obtained.

[0009] Further, in step S1, the concentration of p-FPEAX added to the electron transport layer precursor solution is 1.5~2.5 mg / mL, and the mass ratio of the added crown ether to p-FPEAX is 2:1.

[0010] Further, in step S1, the crown ether is one of 18-crown ether-6, 15-crown ether-5, 12-crown ether-4, dibenzo-24-crown ether-8, and dibenzo-18-crown ether-6.

[0011] Further, in step S1, the electron transport layer material is 2,4,6-tris[3-(diphenylphosphino)phenyl]-1,3,5-triazole (PO-T2T), and the organic solvent is chlorobenzene (CB).

[0012] Furthermore, in step S2, the spin coating conditions include: 2000~2500 r / min, and a time of 30~40s.

[0013] Furthermore, the precursor solution of the hole transport layer of the present invention can be conventionally selected according to the needs of perovskite light-emitting diode fabrication; preferably, the precursor solution of the hole transport layer of the present invention uses a CB solution containing poly(4-phenyl)(2,4,6-trimethylphenyl)amine] (PTAA) and a CB solution containing poly(9-vinylcarbazole) (PVK); after the CB solution containing PTAA and the CB solution containing PVK are sequentially spin-coated onto the anode substrate, annealing is performed to obtain the hole transport layer, preferably, the annealing temperature is 120~130℃.

[0014] Furthermore, the perovskite used in the perovskite luminescent layer of this invention should be CsPbBr. y Cl (3-y) Cs x FA (1-x) PbBr y Cl (3-y) Cs x FA (1-x) PbBr y Cl (3-y) :PEABr, Cs x FA (1-x) PbBr y Cl (3-y) : One of PEACl, where 0.7≤x≤0.95 and 0.5≤y≤1.2.

[0015] Furthermore, when the material of the perovskite light-emitting layer is Cs x FA (1-x) PbBr y Cl (3-y) When using PEABr, preferably, the precursor solution of the perovskite luminescent layer is prepared by dissolving cesium bromide, formamidinium bromide, lead bromide, lead chloride, p-fluorophenylethylamine bromide, lithium bromide, and crown ether in dimethyl sulfoxide (DMSO) solvent, wherein the molar percentages of cesium bromide, formamidinium bromide, lead bromide, lead chloride, p-fluorophenylethylamine bromide, and lithium bromide are 1.00:0.30:0.57:0.42:0.15:0.11, and the dissolved Pb 2+ The total concentration of ions in the DMSO solvent is 0.3 mol / L, and the concentration of crown ether in the DMSO solvent is 7 mg / mL; the crown ether can be any one of 18-crown ether-6, 15-crown ether-5, 12-crown ether-4, dibenzo-24-crown ether-8, and dibenzo-18-crown ether-6; after spin-coating the precursor solution of the perovskite luminescent layer onto the hole transport layer, the perovskite luminescent layer is formed by annealing.

[0016] It should be noted that the present invention does not have any special limitations on the composition and content of the precursor solution for the perovskite luminescent layer. As long as the material obtained is bromochloro-based blue luminescent perovskite, the host-guest complex described in this invention can achieve excellent passivation effects on it. The above-mentioned precursor solution formulation is only a preferred embodiment of the present invention, wherein the type of crown ether can be the same as or different from the crown ether contained in the host-guest complex.

[0017] Furthermore, the spin coating speed of the precursor solution of the perovskite light-emitting layer on the hole transport layer is 4000~4500 r / min, and the annealing temperature is preferably 80℃.

[0018] Furthermore, the cathode electrode is a LiF / Al electrode, which is deposited on the electron transport layer by vacuum evaporation.

[0019] The present invention also provides a host-guest composite passivated perovskite light-emitting diode, which is prepared by the above-mentioned all-solution preparation method of the host-guest composite passivated perovskite light-emitting diode; the structure of the prepared perovskite light-emitting diode from bottom to top is an anode substrate, a hole transport layer, a perovskite light-emitting layer, an electron transport layer and a cathode electrode.

[0020] Unlike existing technologies, this invention has the following advantages: 1. In the process of preparing blue perovskite light-emitting diodes using the all-solution method, this invention employs a host-guest complex composite passivation strategy. Crown ether and p-FPEAX are added as the host and guest, respectively, to the electron transport layer precursor solution and self-assemble to form a host-guest complex. p-FPEAX can be any one of p-FPEACl and p-FPEABr, which can mildly passivate surface defects, reduce grain boundary electron accumulation, lower the surface work function, and introduce X ions (Cl...). - ,Br - Crown ethers can achieve in-situ repair of some lost halide anions in the perovskite lattice; crown ethers can interact with undercoordinated cations (such as FA) on the surface of blue light perovskites. + Cs + Pb 2+ (etc.) to form stable coordination bonds, reducing carrier defect density; the combination of the two can effectively fill the uncoordinated halide anion and cation defects on the surface of the perovskite luminescent layer caused by the whole solution preparation method, while suppressing the inherent bulk ion migration and phase separation problems of traditional bromochloro-based blue light perovskites, thereby achieving the elimination of the transport barrier, the improvement of carrier lifetime and extraction efficiency, and the dual stabilization of defects and performance improvement; at the same time, the host-guest interaction between crown ether and p-FPEAX also promotes the solubility of p-FPEAX in the electron transport layer precursor solution, further enhancing its defect passivation effect.

[0021] 2. This invention coats an electron transport layer precursor solution doped with a host-guest composite onto a perovskite emitting layer, achieving in-situ passivation of defects in the perovskite emitting layer and deposition of the electron transport layer in one step. This opens up a new path for low-cost, all-solution-based fabrication of high-performance perovskite emitting diodes. Compared to untreated perovskite films, the perovskite film of the emitting diode provided by this invention exhibits a maximum brightness and maximum external quantum efficiency of 3284 cd / m², significantly higher than that of films without host-guest post-treatment. -2 And 2.7%, increasing to 8740 cd m -2 The electroluminescent quantum yield increased from 53.2% for the untreated perovskite film to 74.2%, and the quantum yield increased to 14.75%. Attached Figure Description

[0022] Figure 1 (a~c) are scanning electron microscope images of the perovskite luminescent layer (initial film) prepared in step S2 of Example 1, the perovskite luminescent layer (solvent-washed film) prepared in step S4 of Comparative Example 1 after depositing the electron transport layer, and the perovskite luminescent layer (host-guest treated film) prepared in step S4 of Example 1, respectively.

[0023] Figure 2 (a~c) are atomic force microscopy scans of the initial film in Example 1, the solvent-washed film in Comparative Example 1, and the host-guest treated film in Example 1, respectively.

[0024] Figure 3 The images show the XRD diffraction patterns of the initial film in Example 1, the solvent-washed film in Comparative Example 1, and the host-guest treated film in Example 1.

[0025] Figure 4 The images show the ultrafast femtosecond transient absorption spectrum (a), time-resolved transient fluorescence spectrum (b), photoluminescence spectrum (c), and corresponding radiative and nonradiative recombination probability diagrams (d) of the initial film in Example 1, the solvent-washed film in Comparative Example 1, and the host-guest treated film in Example 1.

[0026] Figure 5 The image shows a cross-sectional view (a) of the device structure of the host-guest composite passivated perovskite light-emitting diode prepared in Example 1, a schematic diagram (b) of the device structure, and the electroluminescence spectrum of the device under this structure as a function of voltage (2.2~4.6V), and a photograph (top right corner) of the device emitting light at a voltage of 4.6V (c). Detailed Implementation

[0027] The present invention will be further described below with reference to the accompanying drawings and preferred embodiments. The embodiments given are only for illustrating the present invention and are not intended to limit the scope of the present invention.

[0028] This invention provides a host-guest composite passivated blue perovskite light-emitting diode. The device structure, from bottom to top, comprises: an anode substrate, a hole transport layer, a perovskite light-emitting layer, an electron transport layer, and a cathode electrode. The perovskite light-emitting layer is made of bromochloro-based blue perovskite. The device is prepared using an all-solution preparation method, including the following steps: S1. Prepare a hole transport layer precursor solution, and then coat the hole transport layer precursor solution onto the surface of the anode substrate by spin coating. After annealing, a hole transport layer is formed. S2. Prepare a perovskite light-emitting layer precursor solution, and then coat the perovskite light-emitting layer precursor solution onto the surface of the hole transport layer by spin coating. After annealing, a perovskite light-emitting layer is formed. S3. Add p-FPEAX and crown ether to an organic solvent containing electron transport layer material and dissolve them completely. During the dissolution process, p-FPEAX and crown ether self-assemble in the organic solvent to form a host-guest complex, thereby obtaining an electron transport layer precursor solution. S4. Spin-coat the electron transport layer precursor solution onto the perovskite light-emitting layer to passivate the perovskite light-emitting layer. After spin-coating, the electron transport layer is obtained. S5. Deposit a cathode electrode on the electron transport layer to obtain the host-guest composite passivated perovskite light-emitting diode.

[0029] The following specific embodiments illustrate the host-guest composite passivated perovskite light-emitting diode and its whole-solution preparation method provided by the present invention.

[0030] The precursor solution of the hole transport layer of the present invention can be conventionally selected according to the needs of perovskite light-emitting diode fabrication. In the following embodiments, the precursor solution of the hole transport layer is a CB solution containing PTAA and a CB solution containing PVK.

[0031] The perovskite luminescent layer used in this invention is specifically a bromochloro-based blue perovskite, which can be CsPbBr. y Cl (3-y) Cs x FA (1-x) PbBr y Cl (3-y) Cs x FA (1-x) PbBr y Cl (3-y) :PEABr, Cs x FA (1-x) PbBr y Cl (3-y)One of PEACl, wherein 0.7≤x≤0.95 and 0.5≤y≤1.2, the host-guest complex of the present invention can produce good passivation effect on it.

[0032] The perovskite luminescent layer in each of the following embodiments is made of Cs. x FA (1-x) PbBr y Cl (3-y) The PEABr precursor solution for the perovskite luminescent layer was prepared by dissolving cesium bromide, formamidinium bromide, lead bromide, lead chloride, p-fluorophenylethylamine bromide, lithium bromide, and crown ether in DMSO solvent. The molar percentages of cesium bromide, formamidinium bromide, lead bromide, lead chloride, p-fluorophenylethylamine bromide, and lithium bromide were 1.00:0.30:0.57:0.42:0.15:0.11. The dissolved Pb... 2+ The total concentration of ions in DMSO solvent is 0.3 mol / L, and the concentration of crown ether in DMSO solvent is 7 mg / mL; the crown ether is 18-crown ether-6.

[0033] In the following embodiments, p-FPEAX in the host-guest complex is p-FPEABr.

[0034] In the following embodiments, the anode substrate is an ITO substrate.

[0035] In the following embodiments, the electron transport layer material in the electron transport layer precursor solution is PO-T2T, and the organic solvent is CB.

[0036] In the following embodiments, the cathode electrodes are all LiF / Al electrodes, which are deposited on the electron transport layer by vacuum evaporation. Specifically, the ITO substrate, which has been spin-coated to form the hole transport layer, perovskite light-emitting layer, and electron transport layer, is transferred to the vacuum evaporation system, and the vacuum evaporation chamber is evacuated to 2×10⁻⁶. -4 The material was prepared by sequentially depositing 1-2 nm thick LiF and 100-110 nm thick Al under a negative pressure of Pa.

[0037] Example 1 This embodiment provides a method for preparing a host-guest composite passivated blue perovskite light-emitting diode using an all-solution approach, comprising the following steps: S1. Prepare a 16 mg / mL PTAA solution (CB as solvent) and a 3 mg / mL PVK solution (CB as solvent). Spin-coat 50 μL of PTAA solution onto an ITO substrate at 1500 r / min for 40 s, then anneal at 130 ℃ for 15 min. Then spin-coat 50 μL of PVK solution onto an ITO substrate at 4000 r / min for 40 s, then anneal at 130 ℃ for 15 min to obtain the hole transport layer. S2. Cesium bromide (CsBr), formamidine bromide (FABr), lead bromide (PbBr2), lead chloride (PbCl2), p-fluorophenylethylamine bromide (p-FPEABr), and lithium bromide (LiBr) were added to 1 mL of dimethyl sulfoxide (DMSO) solvent in a molar percentage ratio of 1.00:0.30:0.57:0.42:0.15:0.11. The introduced Pb... 2+ The total concentration of ions in DMSO was controlled at 0.3 mol / L, and then 7 mg of 18-crown ether-6 was added to the solution. The resulting solution was stirred overnight to fully dissolve the ions, thus obtaining a perovskite luminescent layer precursor solution. 80 μL of the obtained clear perovskite luminescent layer precursor solution was dropped onto the hole transport layer and rotated at 4000 r / min for 50 s. The solvent was then dried at 80 °C to obtain the perovskite luminescent layer. S3. Add 2 mg p-FPEABr and 4 mg 18-crown ether-6 to 1 mL of PO-T2T solution (CB solvent) with a concentration of 8 mg / mL and dissolve thoroughly to obtain a host-guest complex electron transport layer precursor solution; S4. Take 40 μL of the host-guest complex electron transport layer precursor solution and spin-coat it onto the perovskite luminescent layer obtained in step S2 at a speed of 2000 r / min for 40 s to form an electron transport layer on the perovskite luminescent layer. S5. Then, the ITO substrate with the deposited hole transport layer, perovskite luminescent layer, and electron transport layer, processed through steps S1 to S4, is transferred to the vacuum evaporation system, and the vacuum evaporation chamber is evacuated to 2×10⁻⁶. -4 Under a negative pressure of Pa, LiF with a thickness of 1 nm and Al with a thickness of 100 nm are sequentially deposited on the electron transport layer to form a LiF / Al cathode electrode, thereby producing the blue perovskite light-emitting diode.

[0038] The blue perovskite light-emitting diode structure obtained in this embodiment consists of, from bottom to top: an anode substrate, a hole transport layer, a perovskite light-emitting layer, an electron transport layer, and a cathode electrode, exhibiting excellent electroluminescence performance.

[0039] Example 2 This embodiment provides a full-solution preparation method for a host-guest composite passivated blue perovskite light-emitting diode, which is basically the same as that in Example 1, except that: In step S2, the spin coating speed of the perovskite light-emitting layer precursor solution on the hole transport layer is 4500 r / min; In step S4, the spin coating speed of the host-guest composite electron transport layer precursor solution on the perovskite luminescent layer is 2500 r / min and the time is 40 s. The remaining steps and conditions are the same as in Example 1, and will not be repeated here.

[0040] The blue perovskite light-emitting diode prepared in this embodiment has the same structure and similar electroluminescent properties as that in Example 1.

[0041] Example 3 This embodiment provides a full-solution preparation method for a host-guest composite passivated blue perovskite light-emitting diode, which is basically the same as that in Example 1, except that: In step S2, the spin coating speed of the perovskite light-emitting layer precursor solution on the hole transport layer is 4200 r / min; In step S4, the spin coating speed of the host-guest complex electron transport layer precursor solution on the perovskite luminescent layer is 2300 r / min and the time is 35 s. The remaining steps and conditions are the same as in Example 1, and will not be repeated here.

[0042] The blue perovskite light-emitting diode prepared in this embodiment has the same structure and similar electroluminescent properties as that in Example 1.

[0043] Comparative Example 1 This comparative example provides a method for preparing a blue perovskite light-emitting diode using an all-solution approach. The difference between this method and Example 1 is that the electron transport layer precursor solution in this method does not contain a host-guest complex. The method for preparing the complete solution includes the following specific steps: S1. Prepare a 16 mg / mL PTAA solution (CB as solvent) and a 3 mg / mL PVK solution (CB as solvent). Spin-coat 50 μL of PTAA solution onto an ITO substrate at 1500 r / min for 40 s, then anneal at 130 °C for 15 min. Then spin-coat 50 μL of PVK solution onto an ITO substrate at 4000 r / min for 40 s, then anneal at 130 °C for 15 min to obtain the hole transport layer. S2. Cesium bromide (CsBr), formamidine bromide (FABr), lead bromide (PbBr2), lead chloride (PbCl2), p-fluorophenylethylamine bromide (p-FPEABr), and lithium bromide (LiBr) were added to 1 mL of DMSO solvent in a molar percentage ratio of 1.00:0.30:0.57:0.42:0.15:0.11. The introduced Pb... 2+ The total concentration of ions in DMSO was controlled at 0.3 mol / L, and then 7 mg of 18-crown ether-6 was added to the solution. The resulting solution was stirred overnight to fully dissolve the ions, thus obtaining a perovskite luminescent layer precursor solution. 80 μL of the clear perovskite luminescent layer precursor solution was dropped onto the hole transport layer and rotated at 4000 r / min for 50 s. The solvent was then dried at 80 °C to obtain the perovskite luminescent layer. S3. Use 1 mL of PO-T2T solution (CB solvent) with a concentration of 8 mg / mL as the electron transport layer precursor solution; S4. Take 40 μL of electron transport layer precursor solution and spin-coat it onto the perovskite light-emitting layer obtained in step S2 at a speed of 2000 r / min for 40 s to form an electron transport layer on the perovskite light-emitting layer. S5. Then, the ITO substrate with the deposited hole transport layer, perovskite luminescent layer, and electron transport layer, processed through steps S1 to S4, is transferred to the vacuum evaporation system, and the vacuum evaporation chamber is evacuated to 2×10⁻⁶. -4 Under a negative pressure of Pa, LiF with a thickness of 1 nm and Al with a thickness of 100 nm are sequentially deposited on the electron transport layer to form a LiF / Al cathode electrode, thereby obtaining the blue perovskite light-emitting diode.

[0044] Performance testing This invention characterizes the perovskite luminescent layer of Example 1 before and after the deposition of the electron transport layer, and compares it with the perovskite luminescent layer of Comparative Example 1 after the deposition of the electron transport layer, thereby providing a representative illustration of the passivation effect of the host-guest composite on defects in the perovskite luminescent layer. Since the substrate material of all perovskite luminescent layers is a quasi-two-dimensional perovskite thin film, the perovskite luminescent layer prepared in step S2 of Example 1, the perovskite luminescent layer prepared in step S4 of Example 1 after the deposition of the electron transport layer, and the perovskite luminescent layer prepared in step S4 of Comparative Example 1 after the deposition of the electron transport layer are respectively named: initial film, host-guest treated film, and solvent rinsed film. The characterization results are detailed below: Figure 1(a-c) are scanning electron microscope (SEM) images of the initial film in Example 1, the solvent-washed film in Comparative Example 1, and the host-guest treated film in Example 1, respectively. The surface of the initial film is relatively smooth and uniform, with insignificant structural features. The surface of the solvent-washed film undergoes significant changes, with a large number of clear granular and porous structures appearing, indicating that solvent treatment induces material rearrangement. Compared to the solvent-washed film, the granular structure of the host-guest treated film still exists, but its size, distribution, or contrast has changed. This indicates that the host-guest composite modifies the surface of the solvent-washed film, achieving adjustment of the film surface morphology.

[0045] Figure 2 (a~c) are atomic force microscopy scans of the initial film in Example 1, the solvent-washed film in Comparative Example 1, and the host-guest treated film in Example 1, respectively. The surface of the initial film is relatively smooth and uniform. The surface morphology of the solvent-washed film changes drastically, with obvious granular or porous structures, becoming very rough. The host-guest treated film, which is treated with the host-guest composite, shows that the rough structure caused by solvent washing during electron transport layer deposition is partially filled or covered, and its surface becomes smoother than that of the solvent-washed film.

[0046] Figure 3 The images show the XRD diffraction patterns of the initial film in Example 1, the solvent-washed film in Comparative Example 1, and the host-guest treated film in Example 1. Compared with the initial film, no significant changes were found in the crystal phase of the solvent-washed film and the host-guest treated film, indicating that the treatment process had no significant destructive effect on the perovskite film.

[0047] Figure 4 The images show the ultrafast femtosecond transient absorption spectrum (a), time-resolved transient fluorescence spectrum (b), photoluminescence spectrum (c), and corresponding radiative recombination and nonradiative coincidence probability diagrams (d) of the initial film in Example 1, the solvent-washed film in Comparative Example 1, and the host-guest treated film in Example 1. The results show that the host-guest treated film exhibits the best luminescence performance. This is attributed to the passivation effect of the host-guest complex on perovskite defects, which effectively suppresses the nonradiative recombination channels in the film.

[0048] In summary, by comparing with Comparative Example 1, the all-solution preparation method of the host-guest composite passivated perovskite light-emitting diode provided by the embodiments of the present invention effectively overcomes the problems of multiple defects in the perovskite light-emitting layer and significant non-radiative transition recombination in the traditional all-solution preparation method, and has good application prospects.

[0049] Furthermore, the blue perovskite light-emitting diodes prepared by the all-solution preparation method of the host-guest composite passivated blue perovskite light-emitting diodes provided in this invention also exhibit excellent electroluminescence performance. Figure 5(a) is a cross-sectional scan of the device structure using an electron scanning microscope. Figure 5 (b) is a schematic diagram of the device structure. Figure 5 (c) shows the electroluminescence spectrum of the device under this structure as a function of voltage (2.2~4.6V) and a photograph of the device emitting light at a voltage of 4.6V (top right corner).

[0050] The above description is merely an embodiment of the present invention and does not limit the patent scope of the present invention. Any equivalent structural or procedural transformations made based on the content of the present invention specification, or direct or indirect applications in other related technical fields, are similarly included within the patent protection scope of the present invention.

Claims

1. A method for preparing a host-guest composite passivated blue perovskite light-emitting diode using a complete solution, comprising: sequentially stacking a hole transport layer, a perovskite light-emitting layer, and an electron transport layer from bottom to top on an anode substrate by spin-coating, followed by deposition of a cathode electrode; characterized in that... The perovskite emitting layer is made of bromochloro-based blue light perovskite. When forming an electron transport layer on the perovskite emitting layer by spin coating, the following specific steps are included: S1. Add p-fluorophenylethylamine bromide or p-fluorophenylethylamine chloride and crown ether to an organic solvent containing electron transport layer material and dissolve it completely. During the dissolution process, the added p-fluorophenylethylamine bromide or p-fluorophenylethylamine chloride and crown ether self-assemble in the organic solvent to form a host-guest complex, thereby obtaining an electron transport layer precursor solution. S2. Spin-coat the electron transport layer precursor solution onto the perovskite luminescent layer to passivate the perovskite luminescent layer. After spin-coating, the electron transport layer is obtained.

2. The all-solution preparation method for passivated blue perovskite light-emitting diodes using a host-guest composite according to claim 1, characterized in that, In step S1, the concentration of p-fluorophenylethylamine bromide or p-fluorophenylethylamine chloride added to the electron transport layer precursor solution is 1.5~2.5 mg / mL, and the mass ratio of the added crown ether to p-fluorophenylethylamine bromide or p-fluorophenylethylamine chloride is 2:

1.

3. The method for preparing a host-guest composite passivated blue light-emitting perovskite light-emitting diode according to claim 1, characterized in that, In step S1, the electron transport layer material is 2,4,6-tris[3-(diphenylphosphino)phenyl]-1,3,5-triazole, and the organic solvent is chlorobenzene.

4. The all-solution preparation method of the host-guest composite passivated blue perovskite light-emitting diode according to claim 1, characterized in that, In step S2, the spin coating conditions include: 2000~2500 r / min and a time of 30~40s.

5. The all-solution preparation method of the host-guest composite passivated blue perovskite light-emitting diode according to claim 1, characterized in that, The precursor solution for the hole transport layer comprises a chlorobenzene solution containing poly[bis(4-phenyl)(2,4,6-trimethylphenyl)amine] and a chlorobenzene solution containing poly(9-vinylcarbazole). The chlorobenzene solution containing poly[bis(4-phenyl)(2,4,6-trimethylphenyl)amine] and the chlorobenzene solution containing poly(9-vinylcarbazole) are sequentially spin-coated onto an anode substrate and annealed to form a film, thereby obtaining the hole transport layer.

6. The all-solution preparation method of the host-guest composite passivated blue perovskite light-emitting diode according to claim 1, characterized in that, The bromochloro-blue perovskite is CsPbBr y Cl (3-y) Cs x FA (1-x) PbBr y Cl (3-y) Cs x FA (1-x) PbBr y Cl (3-y) :PEABr, Cs x FA (1-x) PbBr y Cl (3-y) : One of PEACl, where 0.7≤x≤0.95 and 0.5≤y≤1.

2.

7. The all-solution preparation method of the host-guest composite passivated blue perovskite light-emitting diode according to claim 6, characterized in that, When the material of the perovskite light-emitting layer is Cs x FA (1-x) PbBr y Cl (3-y) In the PEABr process, the precursor solution for the perovskite luminescent layer is prepared by dissolving cesium bromide, formamidinium bromide, lead bromide, lead chloride, p-fluorophenylethylamine bromide, lithium bromide, and crown ether in dimethyl sulfoxide solvent. The molar percentages of cesium bromide, formamidinium bromide, lead bromide, lead chloride, p-fluorophenylethylamine bromide, and lithium bromide are 1.00:0.30:0.57:0.42:0.15:0.

11. The dissolved Pb... 2+ The total concentration of the ions in the dimethyl sulfoxide solvent was 0.3 mol / L, and the concentration of the crown ether in the dimethyl sulfoxide solvent was 7 mg / mL; After spin-coating the precursor solution of the perovskite luminescent layer onto the hole transport layer, the perovskite luminescent layer is formed by annealing.

8. The all-solution preparation method of the host-guest composite passivated blue perovskite light-emitting diode according to claim 1, characterized in that, The precursor solution of the perovskite luminescent layer is spin-coated onto the hole transport layer at a rotation speed of 4000~4500 r / min.

9. The all-solution preparation method of the host-guest composite passivated blue perovskite light-emitting diode according to claim 1, characterized in that, The cathode electrode is a LiF / Al electrode, which is deposited on the electron transport layer by vacuum evaporation.

10. A host-guest composite passivated blue perovskite light-emitting diode, characterized in that, It is prepared by the all-solution preparation method of the host-guest composite passivating blue perovskite light-emitting diode according to any one of claims 1 to 9.

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