Perovskite light-emitting diode and preparation method thereof

Abstract

The invention discloses a perovskite light emitting diode, and belongs to the technical field of perovskite light emitting / displaying. The perovskite light-emitting diode comprises a substrate with a transparent electrode, a ZnO electron transport layer, a perovskite light-emitting layer, a hole transport layer, an anode buffer layer and an anode which are arranged in sequence. Wherein the ZnO electron transport layer is a ZnO film subjected to surface modification by adopting an organic silicon cross-linking agent (containing a functional group capable of reacting with amino to form a cross-linked network structure). The surface of the ZnO film is modified by adopting the organic silicon cross-linking agent containing the functional group which can react with the amino group to form the cross-linked network structure, and the cross-linked network structure is formed through the reaction of the functional group and the amino group, so that the mechanical property of the perovskite film is remarkably improved. The method not only enhances the flexibility and crack resistance of the perovskite thin film, but also effectively improves the binding force between the perovskite thin film and the ZnO substrate, and provides powerful support for wide application of the perovskite material in flexible devices.

Description

Technical Field

[0001] The present invention belongs to the technical field of perovskite light-emitting / display, and specifically relates to a method for surface modification of the ZnO electron transport layer of a perovskite light-emitting diode (PeLED) by using a class of organosilicon crosslinking agents (containing functional groups capable of reacting with amino groups to form a crosslinked network structure). Background Art

[0002] In 1907, the British physicist Henry Joseph Round discovered the phenomenon of electroluminescence, laying the theoretical foundation for the birth of the light-emitting diode (LED). In 1993, Shuji Nakamura invented the blue LED based on gallium nitride and indium gallium nitride, paving the way for the advent of white LEDs. In 1999, the first white LED lamp appeared, marking a major breakthrough in LED technology in the field of lighting, and humanity has since entered the era of LED lighting. Perovskite light-emitting diodes (PeLEDs) have become an important development direction in the field of display technology due to their superior optoelectronic properties such as high photoluminescence quantum yield, narrow full-width at half-maximum, and spectral tunability.

[0003] However, perovskite thin films are prone to form cracks and lattice deformation during repeated bending or stretching, resulting in poor mechanical stability of the thin films; at the same time, the interfacial bonding force between the perovskite thin film and the substrate is weak and is prone to separation under mechanical stress. This leads to a sharp drop in the efficiency and shortening of the lifespan of PeLED devices. Many problems limit the application of perovskite materials in flexible devices. The mechanical properties of perovskite thin films are closely related to their microstructure. Perovskite thin films are usually randomly stacked by nanocrystals, and there are a large number of uncoordinated ions (such as Pb 2 +, I-) and dangling bonds at the grain boundaries. These sites are not only mechanical weak points but also channels for ion migration and defect recombination. Conventional passivation strategies can partially suppress defects, but it is difficult to fundamentally enhance the grain boundary bonding force or improve the film's resistance to deformation. In recent years, crosslinking agents have been widely used to optimize the properties of perovskite materials, including improving the mechanical properties, interfacial bonding force, and stability of perovskite thin films. Crosslinking agents can construct three-dimensional network-structured molecules inside the material or at the interface through chemical reactions or physical interactions, enhancing the mechanical force and interfacial bonding strength of the material. There are various types of crosslinking agents, including silanes, amines, ionic liquids, isocyanates, etc. Each type has unique chemical properties and reaction mechanisms. For example, isocyanates can react with amine compounds to form urea groups, which then undergo a condensation reaction with the N=C=O group of the isocyanate, ultimately forming a stable crosslinked structure.

[0004] To address the issues of poor mechanical stability and weak interfacial bonding force of perovskite thin films, introducing a bottom interface crosslinking agent to form a connection layer is an effective solution. By designing a functional interface layer, the bonding force between the perovskite thin film and the substrate is enhanced, mechanical stress concentration is alleviated, and crack propagation is inhibited. Summary of the Invention

[0005] The object of the present invention is to propose a method for preparing perovskite thin films with high mechanical properties by surface modification treatment of the ZnO electron transport layer substrate, aiming at the problems of poor mechanical stability of perovskite thin films and weak bonding force with the substrate. The present invention uses an organosilicon crosslinking agent (containing functional groups that can react with amino groups to form a crosslinked network structure) to modify the surface of the ZnO thin film substrate. By reacting the end groups of the functional groups with amino groups to form a crosslinked network structure, the mechanical properties of the perovskite thin film are significantly improved, not only enhancing the flexibility and crack resistance of the perovskite thin film, but also improving its bonding force with the substrate, providing strong support for the wide application of perovskite materials in flexible devices.

[0006] To achieve the above object, the technical solution adopted by the present invention is as follows:

[0007] A perovskite light-emitting diode includes a substrate with a transparent electrode, a ZnO electron transport layer, a perovskite light-emitting layer, a hole transport layer, an anode buffer layer, and an anode arranged in sequence; wherein, the ZnO electron transport layer is a ZnO thin film modified by surface modification with an organosilicon crosslinking agent containing functional groups, and the functional groups are groups that can react with amino groups to form a crosslinked network structure.

[0008] Further, the structural formula of the organosilicon crosslinking agent containing functional groups is:

[0009]

[0010] Among them, R is a group that can react with amino groups to form a crosslinked network structure, such as epoxy group, acrylate, aldehyde group, anhydride group, isocyanate group, etc.; X is a hydrolyzable group such as methoxy, ethoxy, halogen, acyloxy, etc.

[0011] Preferably, the organosilicon crosslinking agent containing functional groups is GPTES (3-glycidoxypropyltriethoxysilane), TESPDK (dihydro-3-[3-(triethoxysilyl)propyl]furan-2,5-dione), TMSPA (3-trimethoxysilane acrylate propyl ester), γ-ISO-TEOS (isocyanatopropyltriethoxysilane), 3-glycidoxypropyl(dimethoxy)methylsilane, 2-(3,4-epoxycyclohexyl)ethyltriethoxysilane, (3-glycidoxypropyl)dimethyl ethoxysilane, etc.

[0012] Further, the preparation process of the ZnO electron transport layer is:

[0013] (1) Clean the substrate with a transparent electrode.

[0014] (2) Form a ZnO thin film on the cleaned substrate with a transparent electrode.

[0015] (3) Disperse the organosilicon crosslinker containing functional groups in a solvent to prepare a modified solution with a concentration of 0.1 - 100 mg / ml.

[0016] (4) Immerse the ZnO thin film obtained in step 2 completely in the modified solution in step 3, spin - coat, and anneal to obtain a surface - modified ZnO electron - transport layer.

[0017] Preferably, the solvent in step (3) is ethanol, isopropyl alcohol (IPA), or N,N - dimethylformamide (DMF), etc.; the immersion time in step (4) is 1 - 60 s, and the spin - coating speed is 100 - 9,000 r.p.m.

[0018] Further, the transparent electrode is indium tin oxide, tin fluoride oxide, or a flexible transparent conductive substrate; the hole - transport layer is PEDOT:PSS (poly(3,4 - ethylenedioxythiophene) - poly(styrenesulfonic acid)), PVK (poly(9 - vinylcarbazole)), Poly - TPD (poly[bis(4 - phenyl)(4 - butylphenyl)amine]), PF8Cz (poly(9,9 - n - dioctyl - 2,7 - fluorene - alt - 9 - isooctyl - 3,6 - carbazole)), Spiro - OMeTAD (2,2',7,7' - tetra(N,N - diphenylamino) - 9,9' - spirobifluorene), CuS, NiO, and TFB (poly[(9,9 - din - octylfluorene - 2,7 - diyl) - alt - (4,4' - (N - (4 - butyl)phenyl) - diphenylamine)]) etc.; the anode buffer layer is CrO x 、WO3、V2O5、Ti3C2、MoO x etc.; the anode is a metal such as Au, Ag, Cr, Al, Cu, Ni, etc.

[0019] A method for preparing a perovskite light - emitting diode, comprising the following steps:

[0020] Step 1. Solution preparation:

[0021] 1.1 Disperse the organosilicon crosslinker A containing functional groups in the solvent B, oscillate and mix evenly to prepare a mixed solution C with a concentration of 0.1 - 100 mg / ml, providing a uniform modifier solution for the surface modification of the subsequent ZnO thin film.

[0022] 1.2 Take the solutions of halide salt A, halide salt B, and halide salt C in a molar ratio of (1.0 - 5.0):1:(0.05 - 1.5), and mix them evenly to obtain mixed solution A; then add additive D to mixed solution A, stir and mix evenly, and stir and react at room temperature for 1 - 24 h to obtain a perovskite precursor solution; among them, in the perovskite precursor solution, the concentration of halide salt B is 0.01 - 3 mol / L, and the concentration of additive D is 0.01 - 5 mol / L;

[0023] Step 2. Cleaning treatment of the substrate with a transparent electrode:

[0024] Ultrasonically clean the substrate with a transparent electrode successively with acetone, deionized water, and absolute ethanol, and after cleaning, dry it;

[0025] Step 3. Spin-coating ZnO film:

[0026] Form a ZnO nanocrystal film on the cleaned transparent electrode, and then perform thermal annealing on a heating table to obtain a ZnO film;

[0027] Step 4. Surface modification treatment of the electron transport layer:

[0028] Completely immerse the ZnO film obtained in Step 3 in the mixed solution C prepared in Step 1.1 for 1 - 60 s, take it out, spin-coat at a speed of 100 - 9,000 r.p.m. to remove the excess solution, and then perform thermal annealing on a heating table to obtain a surface-modified and modified ZnO film;

[0029] Step 5. Spin-coating the perovskite light-emitting layer:

[0030] Spin-coat the perovskite precursor solution prepared in Step 1 on the modified ZnO electron transport layer, and then perform thermal annealing on a heating table to obtain a perovskite light-emitting layer;

[0031] Step 6. Spin-coating the hole transport layer:

[0032] Form a hole transport layer on the perovskite light-emitting layer;

[0033] Step 7. Evaporating the electrode:

[0034] Use tweezers to scrape off the edge part to expose the negative electrode of the transparent electrode, and then place the device with the spin-coated multi-layer functional layers obtained in Step 6 face down in a fixed-pattern mask template, and evaporate the electrode by vacuum evaporation to obtain the perovskite light-emitting diode.

[0035] Furthermore, in step 1.1, the functional group-containing organosilicon crosslinker A is GPTES (3-glycidyloxypropyltriethoxysilane), TESPDK (dihydro-3-[3-(triethoxysilyl)propyl]furan-2,5-dione), TMSPA (3-trimethoxysilane propyl acrylate), γ-ISO-TEOS (isocyanatepropyltriethoxysilane), 3-glycidoxypropyl(dimethoxy)methylsilane, 2-(3,4-epoxycyclohexyl)ethyltriethoxysilane, (3-glycidoxypropyl)dimethylethoxysilane, etc.; the solvent B is ethanol, isopropyl alcohol (IPA) or N,N-dimethylformamide (DMF), etc.

[0036] Furthermore, in step 1.2, halide salt A is formamidine hydroiodide (FAI), methylamine hydroiodide (MAI), formamidine hydrobromide (FABr) or methylamine hydrobromide (MABr), etc., halide salt B is lead iodide (PbI2), lead bromide (PbBr2), tin iodide (SnI2) or tin bromide (SnI2), etc., halide salt C is cesium iodide (CsI), cesium bromide (CsBr), etc.; additive D is 5-aminovaleric acid (5AVA), 5-aminovaleric acid hydroiodide (5AVAI), 3-oxopentamethylenediamine (EDEA), 1,8-diamino-3,6-dioxaoctane and other additives containing amino terminal groups.

[0037] Compared with the prior art, the present invention has the following beneficial effects:

[0038] 1. The present invention uses a class of organosilicon crosslinking agents (containing functional groups that can react with amino groups to form a crosslinked network structure) to modify the surface of the ZnO film, wherein one end is directionally anchored to the surface of the ZnO film through a Si-O-Zn covalent bond, while the functional groups such as epoxy, acrylate, aldehyde, anhydride, isocyanate, etc. at the other end can react with the active sites at the perovskite grain boundary (such as uncoordinated lead ions Pb 2+ , amino groups in organic amine molecules) form a covalent bond cross-linked network structure, which runs through the perovskite grains to form a continuous three-dimensional support structure, which can effectively disperse the external stress of the perovskite film and reduce crack propagation. It not only enhances the flexibility and crack resistance of the perovskite film, but also improves its bonding with the ZnO substrate.

[0039] 2. The present invention adopts a solution immersion method to modify the surface of the ZnO-based film. Compared with other modification methods, this method is simple to operate and does not require complex instruments or harsh environmental conditions. Under normal atmospheric conditions, the sample only needs to be immersed in a solution containing an organosilicon crosslinking agent, and after sufficient immersion and adsorption, the excess solution can be thrown away using a sizing machine to complete the surface modification of the ZnO film, which greatly reduces the cost and time consumption of the modification process.

[0040] 3. After modification by the method of the present invention, not only the flexibility of the perovskite film and the adhesion to the substrate are improved, but also the EQE efficiency of the PeLED device is enhanced. BRIEF DESCRIPTION OF THE DRAWINGS

[0041] Figure 1 It is a schematic structural diagram of a perovskite light-emitting diode of the present invention;

[0042] Figure 2 It is a schematic molecular structure diagram of the organosilicon crosslinking agent containing functional groups of the present invention;

[0043] Figure 3 It is a schematic diagram of the nucleophilic ring-opening reaction of epoxy alkane and amino group involved in the present invention;

[0044] Figure 4 Optical photographs of perovskite films of Example 1 (Control), Example 2 (BUTES), Example 3 (3-GPTES), Example 4 (TESPDK), Example 5 (TMSPA), and Example 6 (γ-ISO-TEOS) prepared on flexible ITO;

[0045] Figure 5 External quantum efficiency and irradiance-current curves of PeLED devices of Example 7 (Control), Example 8 (BUTES), Example 9 (3-GPTES), Example 10 (TESPDK), Example 11 (TMSPA), and Example 12 (γ-ISO-TEOS); DETAILED DESCRIPTION OF THE EMBODIMENTS

[0046] The present invention will be further described below with reference to the drawings and embodiments.

[0047] Perovskite film of Example 1 control group (Control):

[0048] Using clean gloves, wipe the surface of the flexible ITO with dishwashing liquid to remove stains as much as possible; then ultrasonically clean with acetone, deionized water, and absolute ethanol in turn, and the ultrasonic cleaning time for each solution is 1 - 30 minutes; after the ultrasonic cleaning is completed, dry the surface of the flexible ITO with a nitrogen spray gun, and then perform ultraviolet ozone heating treatment for 1 - 30 minutes; process the ZnO nanocrystal film on the cleaned flexible ITO, and then perform thermal annealing on a heating table to obtain the ZnO film; after cooling to room temperature, process the perovskite precursor solution on the ZnO electron transport layer film, and then perform thermal annealing on a heating table to obtain the perovskite film of the Control group.

[0049] Perovskite film of Example 2 experimental group (BUTES):

[0050] Use clean gloves and wipe the surface of the flexible ITO with dishwashing liquid to remove stains as much as possible; then perform ultrasonic cleaning with acetone, deionized water, and absolute ethanol in sequence, and the ultrasonic cleaning time for each solution is 1 - 30 minutes; after the ultrasonic cleaning is completed, use a nitrogen spray gun to dry the surface of the flexible ITO, and then perform ultraviolet ozone heating treatment for 1 - 30 minutes; fabricate a ZnO nanocrystal film on the cleaned flexible ITO, and then perform thermal annealing on a heating stage to obtain a ZnO film; immerse the obtained ZnO film in an IPA solution containing BUTES, soak it thoroughly for 1 - 60 s, then take it out and quickly put it into a spin coater, and spin coat at a speed of 100 - 9000 r.p.m. to remove the excess solution. After the spin coating is completed, perform thermal annealing on a heating stage to obtain a ZnO film modified by surface modification with BUTES; after cooling to room temperature, fabricate a perovskite precursor solution on the modified ZnO electron transport layer, and then perform thermal annealing on a heating stage to obtain a perovskite film of the BUTES group.

[0051] Perovskite film of the experimental group (3 - GPTES) in Example 3:

[0052] Use clean gloves and wipe the surface of the flexible ITO with dishwashing liquid to remove stains as much as possible; then perform ultrasonic cleaning with acetone, deionized water, and absolute ethanol in sequence, and the ultrasonic cleaning time for each solution is 1 - 30 minutes; after the ultrasonic cleaning is completed, use a nitrogen spray gun to dry the surface of the flexible ITO, and then perform ultraviolet ozone heating treatment for 1 - 30 minutes; fabricate a ZnO nanocrystal film on the cleaned flexible ITO, and then perform thermal annealing on a heating stage to obtain a ZnO film; immerse the obtained ZnO film in an IPA solution containing 3 - GPTES, soak it thoroughly for 1 - 60 s, then take it out and quickly put it into a spin coater, and spin coat at a speed of 100 - 9000 r.p.m. to remove the excess solution. After the spin coating is completed, perform thermal annealing on a heating stage to obtain a ZnO film modified by surface modification with 3 - GPTES; after cooling to room temperature, fabricate a perovskite precursor solution on the modified ZnO electron transport layer, and then perform thermal annealing on a heating stage to obtain a perovskite film of the 3 - GPTES group.

[0053] Perovskite film of the experimental group (TESPDK) in Example 4:

[0054] Use clean gloves and wipe the surface of flexible ITO with dishwashing liquid to remove stains as much as possible; then sequentially perform ultrasonic cleaning with acetone, deionized water, and absolute ethanol, and the ultrasonic cleaning time for each solution is 1 - 30 minutes; after the ultrasonic cleaning is completed, use a nitrogen spray gun to dry the surface of flexible ITO, and then perform ultraviolet ozone heating treatment for 1 - 30 minutes; process ZnO nanocrystal film on the cleaned flexible ITO, and then perform thermal annealing on a heating stage to obtain ZnO film; immerse the obtained ZnO film in an IPA solution containing TESPDK, soak it fully for 1 - 60 s, then take it out and quickly put it into a spin coater, and spin coat at a speed of 100 - 9000 r.p.m. to remove the excess solution. After the spin coating is completed, perform thermal annealing on a heating stage to obtain the ZnO film modified by surface modification with TESPDK; after cooling to room temperature, process the perovskite precursor solution on the modified ZnO electron transport layer, and then perform thermal annealing on a heating stage to obtain the perovskite film of the TESPDK group.

[0055] Perovskite film of the experimental group (TMSPA) in Example 5:

[0056] Use clean gloves and wipe the surface of flexible ITO with dishwashing liquid to remove stains as much as possible; then sequentially perform ultrasonic cleaning with acetone, deionized water, and absolute ethanol, and the ultrasonic cleaning time for each solution is 1 - 30 minutes; after the ultrasonic cleaning is completed, use a nitrogen spray gun to dry the surface of flexible ITO, and then perform ultraviolet ozone heating treatment for 1 - 30 minutes; process ZnO nanocrystal film on the cleaned flexible ITO, and then perform thermal annealing on a heating stage to obtain ZnO film; immerse the obtained ZnO film in an IPA solution containing TMSPA, soak it fully for 1 - 60 s, then take it out and quickly put it into a spin coater, and spin coat at a speed of 100 - 9000 r.p.m. to remove the excess solution. After the spin coating is completed, perform thermal annealing on a heating stage to obtain the ZnO film modified by surface modification with TMSPA; after cooling to room temperature, process the perovskite precursor solution on the modified ZnO electron transport layer, and then perform thermal annealing on a heating stage to obtain the perovskite film of the TMSPA group.

[0057] Perovskite film of the experimental group (γ - ISO - TEOS) in Example 6:

[0058] Use clean gloves and wipe the surface of the flexible ITO with dishwashing liquid to remove stains as much as possible; then sequentially perform ultrasonic cleaning with acetone, deionized water, and absolute ethanol, and the ultrasonic cleaning time for each solution is 1 - 30 minutes; after the ultrasonic cleaning is completed, use a nitrogen spray gun to dry the surface of the flexible ITO, and then perform ultraviolet ozone heating treatment for 1 - 30 minutes; process the ZnO nanocrystal film on the cleaned flexible ITO, and then perform thermal annealing on a hot plate to obtain the ZnO film; immerse the obtained ZnO film in an IPA solution containing γ-ISO-TEOS, soak it thoroughly for 1 - 60 s, then take it out and quickly put it into a spin coater, and spin coat at a speed of 100 - 9000 r.p.m. to remove the excess solution. After the spin coating is completed, perform thermal annealing on a hot plate to obtain the ZnO film modified by γ-ISO-TEOS surface modification; after cooling to room temperature, process the perovskite precursor solution on the modified ZnO electron transport layer, and then perform thermal annealing on a hot plate to obtain the perovskite film of the γ-ISO-TEOS group.

[0059] Example 7 Control group PeLED device:

[0060] Use clean gloves and wipe the surface of the flexible ITO with dishwashing liquid to remove stains as much as possible; then sequentially perform ultrasonic cleaning with acetone, deionized water, and absolute ethanol, and the ultrasonic cleaning time for each solution is 1 - 30 minutes; after the ultrasonic cleaning is completed, use a nitrogen spray gun to dry the surface of the flexible ITO, and then perform ultraviolet ozone heating treatment for 1 - 30 minutes; process the ZnO nanocrystal film on the cleaned flexible ITO, and then perform thermal annealing on a hot plate to obtain the ZnO film; after cooling to room temperature, process the perovskite precursor solution on the ZnO electron transport layer film, and then perform thermal annealing on a hot plate to obtain the perovskite film; then process TFB on the perovskite film to form a hole transport layer; finally, use tweezers to scrape off the edge part to expose the ITO negative electrode, and then place the device with the spin-coated multi-layer functional layer face down in a fixed pattern mask, and evaporate the Au electrode by vacuum evaporation to obtain the Control group PeLED device.

[0061] Example 8 Experimental group (BUTES) PeLED device:

[0062] Wear clean gloves and wipe the surface of the flexible ITO with dishwashing liquid to remove stains as much as possible; then perform ultrasonic cleaning with acetone, deionized water, and absolute ethanol in sequence, and the ultrasonic cleaning time for each solution is 1 - 30 minutes; after the ultrasonic cleaning is completed, use a nitrogen spray gun to dry the surface of the flexible ITO, and then perform ultraviolet ozone heating treatment for 1 - 30 minutes; process the ZnO nanocrystal film on the cleaned flexible ITO, and then perform thermal annealing on a hot plate to obtain the ZnO film; immerse the obtained ZnO film in an IPA solution containing BUTES, soak it thoroughly for 1 - 60 s, then take it out and quickly put it into a spin coater, and spin coat at a speed of 100 - 9000 r.p.m. to remove the excess solution. After the spin coating is completed, perform thermal annealing on a hot plate to obtain the ZnO film modified by surface modification of BUTES; after cooling to room temperature, process the perovskite precursor solution on the modified ZnO electron transport layer, and then perform thermal annealing on a hot plate to obtain the perovskite film of the BUTES group; then process TFB on the perovskite film to form a hole transport layer; finally, use tweezers to scrape off the edge part to expose the ITO negative electrode, and then place the device with multiple functional layers spin-coated face down into a fixed pattern mask, and deposit the Au electrode by vacuum evaporation to obtain the PeLED device of the BUTES group.

[0063] Example 9 Experimental Group (3 - GPTES) PeLED Device:

[0064] Wear clean gloves and wipe the surface of the flexible ITO with dishwashing liquid to remove stains as much as possible; then perform ultrasonic cleaning with acetone, deionized water, and absolute ethanol in sequence, and the ultrasonic cleaning time for each solution is 1 - 30 minutes; after the ultrasonic cleaning is completed, use a nitrogen spray gun to dry the surface of the flexible ITO, and then perform ultraviolet ozone heating treatment for 1 - 30 minutes; process the ZnO nanocrystal film on the cleaned flexible ITO, and then perform thermal annealing on a hot plate to obtain the ZnO film; immerse the obtained ZnO film in an IPA solution containing 3 - GPTES, soak it thoroughly for 1 - 60 s, then take it out and quickly put it into a spin coater, and spin coat at a speed of 100 - 9000 r.p.m. to remove the excess solution. After the spin coating is completed, perform thermal annealing on a hot plate to obtain the ZnO film modified by surface modification of 3 - GPTES; after cooling to room temperature, process the perovskite precursor solution on the modified ZnO electron transport layer, and then perform thermal annealing on a hot plate to obtain the perovskite film of the 3 - GPTES group; then process TFB on the perovskite film to form a hole transport layer; finally, use tweezers to scrape off the edge part to expose the ITO negative electrode, and then place the device with multiple functional layers spin-coated face down into a fixed pattern mask, and deposit the Au electrode by vacuum evaporation to obtain the PeLED device of the 3 - GPTES group.

[0065] Example 10 Experimental Group (TESPDK) PeLED Device:

[0066] Wear clean gloves and wipe the flexible ITO surface with dishwashing liquid to remove stains as much as possible; then perform ultrasonic cleaning with acetone, deionized water, and absolute ethanol in sequence, and the ultrasonic cleaning time for each solution is 1 - 30 minutes; after the ultrasonic cleaning is completed, use a nitrogen spray gun to dry the flexible ITO surface, and then perform ultraviolet ozone heating treatment for 1 - 30 minutes; fabricate a ZnO nanocrystal film on the cleaned flexible ITO, and then perform thermal annealing on a hot plate to obtain a ZnO film; immerse the obtained ZnO film in an IPA solution containing TESPDK, soak it thoroughly for 1 - 60 s, then take it out and quickly put it into a spin coater, and spin coat at a speed of 100 - 9000 r.p.m. to remove the excess solution. After the spin coating is completed, perform thermal annealing on a hot plate to obtain a ZnO film modified by surface modification of TESPDK; after cooling to room temperature, fabricate a perovskite precursor solution on the modified ZnO electron transport layer, and then perform thermal annealing on a hot plate to obtain a perovskite film of the TESPDK group; then fabricate TFB on the perovskite film to form a hole transport layer; finally, use tweezers to scrape off the edge part to expose the ITO negative electrode, and then place the device with multiple functional layers spin-coated face down into a fixed pattern mask, and deposit an Au electrode by vacuum evaporation to obtain a PeLED device of the TESPDK group.

[0067] Example 11 Experimental Group (TMSPA) PeLED Device:

[0068] Use clean gloves and wipe the surface of the flexible ITO with dishwashing liquid to remove stains as much as possible; then perform ultrasonic cleaning with acetone, deionized water, and absolute ethanol in sequence, and the ultrasonic cleaning time for each solution is 1 - 30 minutes; after ultrasonic cleaning is completed, dry the surface of the flexible ITO with a nitrogen spray gun, and then perform ultraviolet ozone heating treatment for 1 - 30 minutes; fabricate a ZnO nanocrystal film on the cleaned flexible ITO, and then perform thermal annealing on a hot plate to obtain a ZnO film; immerse the obtained ZnO film in an IPA solution containing TMSPA, soak it thoroughly for 1 - 60 s, then take it out and quickly put it into a spin coater, and spin coat at a speed of 100 - 9000 r.p.m. to remove the excess solution. After spin coating is completed, perform thermal annealing on a hot plate to obtain a ZnO film modified by surface modification with TMSPA; after cooling to room temperature, fabricate a perovskite precursor solution on the modified ZnO electron transport layer, and then perform thermal annealing on a hot plate to obtain a perovskite film of the TMSPA group; then fabricate TFB on the perovskite film to form a hole transport layer; finally, use tweezers to scrape off the edge part to expose the ITO negative electrode, and then place the device spin-coated with multiple functional layers face down in a fixed pattern mask, and deposit an Au electrode by vacuum evaporation to obtain a PeLED device of the TMSPA group.

[0069] Experimental group of PeLED device in Example 12 (γ-ISO-TEOS):

[0070] Use clean gloves and wipe the surface of the flexible ITO with dishwashing liquid to remove stains as much as possible; then perform ultrasonic cleaning with acetone, deionized water, and absolute ethanol in sequence, and the ultrasonic cleaning time for each solution is 1 - 30 minutes; after ultrasonic cleaning is completed, dry the surface of the flexible ITO with a nitrogen spray gun, and then perform ultraviolet ozone heating treatment for 1 - 30 minutes; fabricate a ZnO nanocrystal film on the cleaned flexible ITO, and then perform thermal annealing on a hot plate to obtain a ZnO film; immerse the obtained ZnO film in an IPA solution containing γ-ISO-TEOS, soak it thoroughly for 1 - 60 s, then take it out and quickly put it into a spin coater, and spin coat at a speed of 100 - 9000 r.p.m. to remove the excess solution. After spin coating is completed, perform thermal annealing on a hot plate to obtain a ZnO film modified by surface modification with γ-ISO-TEOS; after cooling to room temperature, fabricate a perovskite precursor solution on the modified ZnO electron transport layer, and then perform thermal annealing on a hot plate to obtain a perovskite film of the γ-ISO-TEOS group; then fabricate TFB on the perovskite film to form a hole transport layer; finally, use tweezers to scrape off the edge part to expose the ITO negative electrode, and then place the device spin-coated with multiple functional layers face down in a fixed pattern mask, and deposit an Au electrode by vacuum evaporation to obtain a PeLED device of the γ-ISO-TEOS group.

[0071] The above steps have described in detail the preparation processes of the embodiments.

[0072] As Figure 1 is a schematic diagram of the device structure of the PeLED example involved, including an ITO substrate, a ZnO electron transport layer, a perovskite light-emitting layer, a TFB hole transport layer, MoO x anode buffer layer, and an Au anode arranged in sequence; wherein, the ZnO electron transport layer is a ZnO thin film surface-modified by using a class of organosilicon cross-linking agents (containing functional groups capable of reacting with amino groups to form a cross-linked network structure). Figure 2 is a schematic diagram of the molecular structure of some organosilicon cross-linking agents containing functional groups for example. As Figure 3 shown, taking the epoxyalkane functional group as an example to show the cross-linking reaction between the functional group and the amino group, a cross-linked network structure can be formed after the reaction, and this cross-linked network structure can endow the perovskite thin film with good mechanical properties and improve its binding force with the ZnO substrate. As Figure 4 shown, after the perovskite thin films in the Control and BUTES groups were folded repeatedly for more than ten times, obvious cracking marks appeared on the film surface, while there were no obvious changes in the 3-GPTES, TESPDK, TMSPA, and γ-ISO-TEOS groups after being folded repeatedly for more than ten times. It shows that the epoxy group-based, anhydride group-based, acrylate group-based, and isocyanate group-based functional groups on the organosilane cross-linking agent can effectively improve the flexibility of the perovskite thin film and its binding force with the ZnO substrate. As Figure 5 shown, compared with Control and BUTES, the external quantum efficiency (EQE) and radiance of the PeLED devices prepared with ZnO thin films surface-modified by 3-GPTES, TESPDK, TMSPA, and γ-ISO-TEOS have been significantly improved.

[0073] The present invention has been illustrated by the above embodiments, but it should be understood that the above embodiments are only for the purpose of exemplification and illustration, and are not intended to limit the present invention to the scope of the described embodiments. In addition, those skilled in the art can understand that the present invention is not limited to the above embodiments, and more variations and modifications can be made according to the teachings of the present invention, and these variations and modifications all fall within the scope of protection required by the present invention. The scope of protection of the present invention is defined by the appended claims and their equivalent scope.

Claims

1. A perovskite light-emitting diode, characterized in that: It includes a substrate with a transparent electrode, a ZnO electron transport layer, a perovskite light-emitting layer, a hole transport layer, an anode buffer layer and an anode which are arranged in sequence; wherein the ZnO electron transport layer is a ZnO film that is surface-modified by an organic silicon crosslinking agent containing functional groups, and the functional groups are groups that can react with amino groups to form a crosslinked network structure.

2. The perovskite light-emitting diode according to claim 1, characterized in that: The structural formula of the organosilicon crosslinking agent containing functional groups is: Wherein, R is a group that can react with an amino group to form a cross-linked network structure, and X is a hydrolyzable group.

3. The perovskite light-emitting diode according to claim 2, characterized in that: R is an epoxy group, an acrylate group, an aldehyde group, an anhydride group or an isocyanate group, and X is a methoxy group, an ethoxy group, a halogen group or an acyloxy group.

4. The perovskite light-emitting diode according to claim 1, characterized in that: The functional group-containing organic silicon crosslinking agent is 3-glycidyloxypropyl triethoxysilane, dihydro-3-[3-(triethoxysilyl)propyl]furan-2,5-dione, 3-trimethoxysilane propyl acrylate, isocyanate propyl triethoxysilane, 3-glycidoxypropyl (dimethoxy) methyl silane, 2-(3,4-epoxycyclohexyl) ethyl triethoxysilane or (3-glycidoxypropyl) dimethylethoxysilane.

5. The perovskite light-emitting diode according to claim 1, characterized in that: The preparation process of the ZnO electron transport layer is as follows: (1) Cleaning the substrate with the transparent electrode; (2) forming a ZnO thin film on the cleaned substrate with a transparent electrode; (3) dispersing the organosilicon crosslinking agent containing functional groups in a solvent to prepare a modified liquid with a concentration of 0.1 to 100 mg / ml; (4) Immerse the ZnO film obtained in step 2 in a modification solution, spin-coat, and anneal to obtain a surface-modified ZnO electron transport layer.

6. The perovskite light-emitting diode according to claim 1, characterized in that: The transparent electrode is indium tin oxide, fluorine tin oxide or a flexible transparent conductive substrate; the hole transport layer is PEDOT:PSS, PVK, Poly-TPD, PF8Cz, Spiro-OMeTAD, CuS, NiO or TFB; the anode buffer layer is CrO x , WO3, V2O5, Ti3C2 or MoO x ; The anode is Au, Ag, Cr, Al, Cu or Ni.

7. A method for preparing a perovskite light-emitting diode, characterized in that: The following steps are involved: Step 1. Solution preparation: Dispersing the organosilicon crosslinking agent A containing a functional group in the solvent B to prepare a mixed solution C with a concentration of 0.1 to 100 mg / ml; Step 2. Cleaning of the substrate with transparent electrode: Clean the substrate with transparent electrodes and blow dry; Step 3. Spin coating ZnO thin film: Processing and forming a ZnO nanocrystalline film on the cleaned transparent electrode, and thermally annealing to obtain a ZnO film; Step 4. Surface modification of the electron transport layer: The ZnO film obtained in step 3 is immersed in the mixed solution C for 1 to 60 seconds, spin-coated, and thermally annealed to obtain a surface-modified ZnO electron transport layer; Step 5. Spin coating the perovskite light emitting layer: Spin coating a perovskite precursor solution on the modified ZnO electron transport layer, and thermally annealing to obtain a perovskite light-emitting layer; Step 6. Preparation of hole transport layer: Processing and forming a hole transport layer on the perovskite light-emitting layer; Step 7. Evaporation of electrodes: The electrode is evaporated to obtain the perovskite light-emitting diode.

8. The method for preparing a perovskite light-emitting diode according to claim 7, characterized in that: The preparation process of the perovskite precursor solution in step 5 is: taking halide A, halide B and halide C solutions in a molar ratio of (1.0-5.0):1:(0.05-1.5), mixing them evenly to obtain a mixed solution A; then adding additive D to the mixed solution A, stirring and mixing evenly, stirring and reacting at room temperature to obtain a perovskite precursor solution; wherein, in the perovskite precursor solution, the concentration of halide B is 0.01-3 mol / L, and the concentration of additive D is 0.01-5 mol / L.

9. The method for preparing a perovskite light-emitting diode according to claim 8, characterized in that: The halide salt A is formamidine hydroiodide, methylamine hydroiodide, formamidine hydrobromide or methylamine hydrobromide, the halide salt B is lead iodide, lead bromide, tin iodide or tin bromide, the halide salt C is cesium iodide or cesium bromide; the additive D is 5-aminopentanoic acid, 5-aminopentanoic acid hydroiodide, 3-oxopentamethylenediamine or 1,8-diamino-3,6-dioxaoctane.

10. The method for preparing a perovskite light-emitting diode according to claim 7, characterized in that: The functional group-containing organic silicon crosslinking agent A is 3-glycidyloxypropyl triethoxysilane, dihydro-3-[3-(triethoxysilyl)propyl]furan-2,5-dione, 3-trimethoxysilane propyl acrylate, isocyanate propyl triethoxysilane, 3-glycidoxypropyl (dimethoxy) methyl silane, 2-(3,4-epoxycyclohexyl) ethyl triethoxy silane or (3-glycidoxypropyl) dimethylethoxy silane.

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