Perovskite light-emitting diode with stable operation and preparation method thereof

Abstract

The invention discloses a stable-operation 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 and an anode which are arranged in sequence. Wherein the ZnO electron transport layer is a ZnO film which is subjected to surface modification by adopting an amino or halogen-terminated organic silicon coupling agent. The surface of the ZnO thin film is modified by adopting the amino or halogen-terminated organic silicon coupling agent, so that harmful hydroxyl groups exposed on the surface of the ZnO-based thin film can be effectively removed, a siloxane network is formed through hydrolysis, and meanwhile, beneficial amino or halogen-terminated functional groups are exposed; the formed siloxane network can effectively block the harmful deprotonation reaction of the lower layer ZnO to the upper layer perovskite active layer, and the exposed amino or halogen-terminated functional group can induce perovskite to form a high-quality crystal film, thereby realizing the comprehensive improvement of the photoelectric property and stability of the PeLED device.

Description

Technical Field

[0001] The present invention belongs to the technical field of perovskite light-emitting / display, and particularly relates to a perovskite light-emitting diode with stable operation and a preparation method thereof. Background Art

[0002] Light-emitting diodes (LEDs) have basically replaced incandescent lamps with extremely low energy conversion efficiency due to their high efficiency and low energy consumption. LEDs can be made of crystalline epitaxial III-V semiconductors or solution-processed light-emitting materials (such as organic semiconductors, quantum dots, and halide perovskites). Among them, halide perovskite semiconductors have the advantages of high carrier mobility, high photoluminescence efficiency, easy adjustment of emission peak position, high defect tolerance, easy preparation, and low cost, and are used to prepare bright and efficient perovskite light-emitting diodes (PeLEDs). Currently, the external quantum efficiency (EQE) of near-infrared, red, and green perovskite light-emitting devices has all exceeded 30%, comparable to commercial OLEDs. Although PeLEDs have made significant progress in efficiency EQE, their short device lifetime remains a difficult challenge to overcome, seriously hindering the wide application of cost-effective PeLEDs. Therefore, exploring effective strategies to improve the device lifetime of perovskite LEDs is of great significance for promoting the development of the lighting and display industries.

[0003] Traditional organic transport layer materials are one of the key factors leading to insufficient efficiency and stability of PeLED devices due to their low mobility and instability of the materials themselves. In contrast, ZnO nanocrystals have the advantages of high electron mobility, excellent optical transparency, high stability, non-toxicity, and low-temperature solution processing, and have been successfully widely applied in PeLEDs. The surface chemical properties and morphology of ZnO nanocrystal thin films have a significant impact on the film formation and crystallization quality of the perovskite layer. The surface of ZnO nanocrystals has a complex state, such as oxygen vacancies, surface active sites, and ligands, which may introduce additional non-radiative recombination centers and trigger harmful deprotonation reactions with the perovskite light-emitting layer, affecting the crystallization and stability of the perovskite layer, and thus having a negative impact on the device performance and stability. Currently, the research on the ZnO-perovskite interface is not sufficient, especially the passivation strategy for efficiently and stably suppressing the reaction activity of ZnO thin films requires further research and exploration.

[0004] Research shows that surface modification of ZnO nanocrystal-based thin films can effectively improve the device efficiency and operating lifetime of PeLEDs. The surface of ZnO nanocrystal thin films has strong alkalinity, which can induce harmful deprotonation reactions with perovskites. This alkalinity mainly comes from oxygen vacancies and adsorbed hydroxyl groups on the surface of ZnO nanocrystals. Current research mainly focuses on surface modification and passivation of oxygen vacancies in ZnO nanocrystal thin films. However, a large number of hydroxyl groups on the surface of ZnO nanocrystals can also have a negative impact on the quality of the upper perovskite thin film. This problem has not been concerned in the field, and there is a lack of efficient passivation strategies for treating harmful hydroxyl groups on the surface of ZnO nanocrystal thin films. The present invention will start from the hydroxyl groups on the surface of ZnO nanocrystal thin films and modify the surface of ZnO nanocrystal thin films with a class of amino- or halogen-terminated organosilane coupling agents to improve the EQE and stability of PeLEDs. Summary of the Invention

[0005] The purpose of the present invention is to propose a surface modification method for ZnO electron transport layer thin films in view of the problem of improving the external quantum efficiency and stability of perovskite light-emitting diodes. The present invention uses amino- or halogen-terminated organosilane coupling agents to modify the surface of ZnO nanocrystal thin film substrates to induce the formation of high-quality perovskite thin films and weaken the harmful deprotonation reactions between ZnO thin films and perovskite light-emitting layers.

[0006] To achieve the above purpose, the technical solutions adopted by the present invention are as follows:

[0007] A stable 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 surface-modified with an amino- or halogen-terminated organosilane coupling agent.

[0008] Furthermore, the structural formula of the amino- or halogen-terminated organosilane coupling agent is:

[0009]

[0010] Among them, R is an amino or halogen group, and X is a hydrolyzable group such as methoxy, ethoxy, halogen, acyloxy, etc.

[0011] Preferably, the amino or halogen-terminated organosilicon coupling agent is 3-(2-aminoethylamino)propyltrimethoxysilane (AEAPTMS), (3-iodopropyl)trimethoxysilane (IPTMS), 3-aminopropyltriethoxysilane, 3-aminopropyltriethoxysilane, 3-aminopropyltriethoxysilane, N1-(3-(trimethoxysilyl)propyl)ethane-1,2-diamine, N-methyl-3-aminopropyltrimethoxysilane, [3-(N,N-dimethylamino)propyl]trimethoxysilane, bis[3-(triethoxysilyl)propyl]amine, 3-bromopropyltrimethoxysilane, 3-chloropropyltrimethoxysilane, trifluoropropane trimethoxysilane, etc.

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

[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 amino or halogen-terminated organosilicon coupling agent in a solvent to prepare a modified solution with a concentration of 0.01 - 50 mg / ml.

[0016] (4) Drop the modified solution onto the ZnO thin film obtained in step 2, 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 rotation speed of the spin-coating in step (4) 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'-tetrakis(N,N-diphenylamino)-9,9'-spirobifluorene), CuS, NiO, and TFB (poly[(9,9-dioctylfluorene-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 preparation method of a perovskite light-emitting diode with stable operation, comprising the following steps:

[0020] Step 1. Solution preparation:

[0021] 1.1 Disperse the amino- or halogen-terminated organosilicon coupling agent A in the solvent B, mix well by oscillation, and prepare a mixed solution C with a concentration of 0.01-50 mg / ml;

[0022] 1.2 Measure the solutions of halide salt A, halide salt B, and halide salt C in a molar ratio of (1.5-5.0):1:(0.1-1.5), and mix well to obtain a mixed solution A; then add the additive D to the mixed solution A, stir and mix well, and stir and react at a temperature of 50-90 °C for 1-24 h to obtain a perovskite precursor solution; wherein, 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, blow dry;

[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] Drop the mixed solution C onto the ZnO film obtained in Step 3, and then spin-coat at a rotation speed of 100-9,000 r.p.m. After spin-coating, perform thermal annealing on a heating table to obtain a surface-modified and modified ZnO electron transport layer;

[0029] Step 5. Spin-coating 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 hole transport layer:

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

[0033] Step 7. Evaporation of electrodes:

[0034] Scrape off the edge part with tweezers to expose the negative electrode of the transparent electrode. Then, place the device with the spin-coated multi-layer functional layer obtained in Step 7 face down into a fixed-pattern mask template, and deposit the electrode by vacuum evaporation to obtain the perovskite light-emitting diode.

[0035] Further, in Step 1.1, the amino- or halogen-terminated organosilane coupling agent A is 3-(2-aminoethylamino)propyltrimethoxysilane (AEAPTMS), (3-iodopropyl)trimethoxysilane (IPTMS), 3-aminopropyltriethoxysilane, 3-aminopropyltriethoxysilane, 3-aminopropyltriethoxysilane, N1-(3-(trimethoxysilyl)propyl)ethane-1,2-diamine, N-methyl-3-aminopropyltrimethoxysilane, [3-(N,N-dimethylamino)propyl]trimethoxysilane, bis[3-(triethoxysilyl)propyl]amine, 3-bromopropyltrimethoxysilane, 3-chloropropyltrimethoxysilane, trifluoropropane trimethoxysilane, etc.; the solvent B is ethanol, isopropyl alcohol (IPA), or N,N-dimethylformamide (DMF), etc.

[0036] Further, in Step 1.2, the halide salt A is formamidinium hydroiodide (FAI), methylammonium hydroiodide (MAI), formamidinium hydrobromide (FABr), or methylammonium hydrobromide (MABr), etc., the halide salt B is lead iodide (PbI2), lead bromide (PbBr2), tin iodide (SnI2), or tin bromide (SnI2), etc., the halide salt C is cesium iodide (CsI), cesium bromide (CsBr), etc.; the additive D is an amino-containing additive such as 5-aminopentanoic acid (5AVA), 5-aminopentanoic acid hydroiodide (5AVAI), 3-oxopentanediamine (EDEA), 1,8-diamino-3,6-dioxaoctane, etc.

[0037] Compared with the prior art, the beneficial effects of the present invention are as follows:

[0038] 1. By using an amino- or halogen-terminated organosilane coupling agent to directionally modify the surface of the ZnO film, the present invention realizes dual-functional optimization: (1) At the ZnO interface layer: Through the hydrolysis and condensation reaction of the coupling agent, the highly reactive free hydroxyl groups (-OH) on the surface of the ZnO-based film are effectively removed, inhibiting the interfacial side reactions caused by them; simultaneously, a dense cross-linked siloxane network barrier layer is constructed, significantly blocking the direct contact between the underlying ZnO and the upper perovskite active layer, thereby blocking the deprotonation erosion effect of ZnO on the perovskite components. (2) At the perovskite functional layer: Utilize the amino (-NH2) or halogen (X-) functional groups exposed at the end of the organosilane coupling agent to coordinate with the unsaturated Pb 2+ / Sn 2+Ions form strong coordination bonds (N→Pb or X→Pb), precisely filling metal ion vacancy defects, reducing the density of surface dangling bonds and suppressing non-radiative recombination. At the same time, the lone pair electrons of amino groups or the negative charges of halogen ions can occupy lattice halogen vacancies (such as I- vacancies), effectively inhibiting the formation of deep-level defect states. Thereby improving the crystallization quality and optoelectronic properties of perovskite thin films and enhancing the luminous efficiency of perovskite light-emitting diodes.

[0039] 2. The present invention uses the solution spin-coating method to modify the surface of ZnO-based thin films. Compared with other modification methods, this method is simple to operate and does not rely on complex instruments or harsh environmental conditions. Under normal atmospheric conditions, only a spin coater is needed to directly modify the surface of ZnO thin films, greatly reducing the cost and time consumption of the modification process.

[0040] 3. After modification using the method of the present invention, not only the EQE efficiency of PeLED devices is improved, but also the stability of the devices is significantly enhanced. It shows that the modification of the present invention greatly improves the stability of PeLED while maintaining the efficiency improvement. 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 an amino- or halogen-terminated organosilane coupling agent of the present invention;

[0043] Figure 3 It is a schematic diagram of hydrolysis and condensation of an amino- or halogen-terminated organosilane coupling agent on a ZnO thin film;

[0044] Figure 4 It is an X-ray photoelectron spectroscopy (XPS) diagram of Si element for Example 1 and Example 2;

[0045] Figure 5 It is an X-ray photoelectron spectroscopy (XPS) diagram of O element for Example 1 and Example 2;

[0046] Figure 6 It is an X-ray diffraction (XRD) spectrum of the thermal stability of perovskite thin films for Example 3 (Control) and Example 6 (AEAPTMS);

[0047] Figure 7 It is an X-ray diffraction (XRD) spectrum of perovskite thin films for Example 3 (Control), Example 4 (BUTMS), Example 5 (IPTMS), and Example 6 (AEAPTMS);

[0048] Figure 8External quantum efficiency and irradiance-current curves of the PeLED devices of Example 7 (Control), Example 8 (IPTMS), and Example 9 (AEAPTMS);

[0049] Figure 9 Operating stability curves of the PeLED devices of Example 7 (Control), Example 8 (IPTMS), and Example 9 (AEAPTMS). Detailed implementation manners

[0050] The present invention will be further described below in conjunction with the accompanying drawings and embodiments.

[0051] ZnO thin film of Example 1 control group:

[0052] Use clean gloves to wipe the 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 ultrasonic cleaning is completed, dry the ITO surface with a nitrogen spray gun, and then perform ultraviolet ozone heating treatment for 1 - 30 minutes; fabricate a ZnO nanocrystal thin film on the cleaned ITO, and then perform thermal annealing on a heating table to obtain a ZnO thin film.

[0053] ZnO / AEAPTMS thin film of Example 2 experimental group:

[0054] Use clean gloves to wipe the 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 ultrasonic cleaning is completed, dry the ITO surface with a nitrogen spray gun, and then perform ultraviolet ozone heating treatment for 1 - 30 minutes; fabricate a ZnO nanocrystal thin film on the cleaned ITO, and then perform thermal annealing on a heating table to obtain a ZnO thin film; then perform surface modification treatment on the ZnO thin film, drop the IPA solution of AEAPTMS onto the ZnO thin film, wait for 1 - 60 s and then spin-coat at a speed of 100 - 9,000 r.p.m., after spin-coating, perform thermal annealing at 10 - 300 °C on a heating table for 1 - 60 mins to obtain a surface-modified ZnO / AEAPTMS thin film.

[0055] Perovskite thin film of Example 3 control group (Control):

[0056] Use clean gloves and wipe the ITO surface with dishwashing liquid to remove stains as much as possible; then perform ultrasonic cleaning successively with acetone, deionized water, and absolute ethanol, and the ultrasonic cleaning time for each solution is 1 - 30 minutes; after ultrasonic cleaning is completed, use a nitrogen spray gun to dry the ITO surface, and then perform ultraviolet ozone heating treatment for 1 - 30 minutes; fabricate a ZnO nanocrystal film on the cleaned ITO, and then perform thermal annealing on a heating stage to obtain a ZnO film; after cooling to room temperature, fabricate a perovskite precursor solution on the ZnO electron transport layer film, and then perform thermal annealing on a heating stage to obtain a perovskite film of the Control group.

[0057] Perovskite film of Experimental Group (BUTES) in Example 4:

[0058] Use clean gloves and wipe the ITO surface with dishwashing liquid to remove stains as much as possible; then perform ultrasonic cleaning successively with acetone, deionized water, and absolute ethanol, and the ultrasonic cleaning time for each solution is 1 - 30 minutes; after ultrasonic cleaning is completed, use a nitrogen spray gun to dry the ITO surface, and then perform ultraviolet ozone heating treatment for 1 - 30 minutes; fabricate a ZnO nanocrystal film on the cleaned ITO, and then perform thermal annealing on a heating stage to obtain a ZnO film; then perform surface modification treatment on the ZnO film, drop the IPA solution of BUTMS onto the ZnO electron transport layer, wait for 1 - 60 s and then spin - coat at a speed of 100 - 9,000 r.p.m., after spin - coating, perform thermal annealing at 10 - 300 °C on a heating stage for 1 - 60 mins to obtain a surface - modified and modified ZnO electron transport layer; after cooling to room temperature, fabricate a perovskite precursor solution on the modified ZnO electron transport layer film, and then perform thermal annealing on a heating stage to obtain a perovskite film of the BUTES group.

[0059] Perovskite film of Experimental Group (IPTMS) in Example 5:

[0060] Use clean gloves and wipe the ITO surface with dishwashing liquid to remove stains as much as possible; then perform ultrasonic cleaning successively with acetone, deionized water, and absolute ethanol, and the ultrasonic cleaning time for each solution is 1 - 30 minutes; after ultrasonic cleaning is completed, blow dry the ITO surface with a nitrogen spray gun, and then perform ultraviolet ozone heating treatment for 1 - 30 minutes; fabricate a ZnO nanocrystal film on the cleaned ITO, and then perform thermal annealing on a heating stage to obtain a ZnO film; then perform surface modification treatment on the ZnO film, drop the IPA solution of IPTMS onto the ZnO film, wait for 1 - 60 s and then spin-coat at a rotation speed of 100 - 9,000 r.p.m., after spin-coating is completed, perform thermal annealing at 10 - 300 °C on the heating stage for 1 - 60 mins to obtain a surface-modified and modified ZnO electron transport layer film; after cooling to room temperature, fabricate a perovskite precursor solution on the modified ZnO electron transport layer film, and then perform thermal annealing on a heating stage to obtain a perovskite film of the IPTMS group.

[0061] Perovskite film of the experimental group (AEAPTMS) in Example 6:

[0062] Use clean gloves and wipe the ITO surface with dishwashing liquid to remove stains as much as possible; then perform ultrasonic cleaning successively with acetone, deionized water, and absolute ethanol, and the ultrasonic cleaning time for each solution is 1 - 30 minutes; after ultrasonic cleaning is completed, blow dry the ITO surface with a nitrogen spray gun, and then perform ultraviolet ozone heating treatment for 1 - 30 minutes; fabricate a ZnO nanocrystal film on the cleaned ITO, and then perform thermal annealing on a heating stage to obtain a ZnO film; then perform surface modification treatment on the ZnO film, drop the IPA solution of AEAPTMS onto the ZnO film, wait for 1 - 60 s and then spin-coat at a rotation speed of 100 - 9,000 r.p.m., after spin-coating is completed, perform thermal annealing at 10 - 300 °C on the heating stage for 1 - 60 mins to obtain a surface-modified and modified ZnO electron transport layer film; after cooling to room temperature, fabricate a perovskite precursor solution on the modified ZnO electron transport layer film, and then perform thermal annealing on a heating stage to obtain a perovskite film of the AEAPTMS group.

[0063] Control group (Control) PeLED device in Example 7:

[0064] Use clean gloves and wipe the 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 ultrasonic cleaning is completed, blow dry the ITO surface with a nitrogen spray gun, and then perform ultraviolet ozone heating treatment for 1 - 30 minutes; in a humidity-controlled glove box, fabricate a ZnO nanocrystal thin film on the cleaned ITO, and then perform thermal annealing on a heating stage to obtain a ZnO thin film; after cooling to room temperature, fabricate a perovskite precursor solution on the ZnO electron transport layer thin film, and then perform thermal annealing on a heating stage to obtain a perovskite light-emitting layer; then fabricate TFB on the perovskite light-emitting layer 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 template, and evaporate the Au electrode by vacuum evaporation to obtain the PeLED device of the Control group.

[0065] Example 8 experimental group (IPTMS) PeLED device:

[0066] Use clean gloves and wipe the 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 ultrasonic cleaning is completed, blow dry the ITO surface with a nitrogen spray gun, and then perform ultraviolet ozone heating treatment for 1 - 30 minutes; fabricate a ZnO nanocrystal thin film on the cleaned ITO, and then perform thermal annealing on a heating stage to obtain a ZnO thin film; then perform surface modification treatment on the ZnO thin film, drop the IPA solution of IPTMS onto the ZnO thin film, wait for 1 - 60 s and then spin-coat at a speed of 100 - 9,000 r.p.m., after the spin-coating is completed, perform thermal annealing at 10 - 300 °C for 1 - 60 mins on a heating stage in the glove box to obtain a surface-modified and modified ZnO electron transport layer; 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 light-emitting layer; then fabricate TFB on the perovskite light-emitting layer 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 template, and evaporate the Au electrode by vacuum evaporation to obtain the PeLED device of the IPTMS group.

[0067] Example 9 experimental group (AEAPTMS) PeLED device:

[0068] Use clean gloves and wipe the ITO surface with dishwashing liquid to remove stains as much as possible; then ultrasonically clean 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, blow dry the ITO surface with a nitrogen spray gun, and then perform ultraviolet ozone heating treatment for 1 - 30 minutes; fabricate a ZnO nanocrystal thin film on the cleaned ITO, and then perform thermal annealing on a heating stage to obtain a ZnO thin film; then perform surface modification treatment on the ZnO thin film, drop the IPA solution of AEAPTMS onto the ZnO thin film, wait for 1 - 60 s and then spin-coat at a speed of 100 - 9,000 r.p.m., after spin-coating is completed, perform thermal annealing at 10 - 300 °C for 1 - 60 mins on a heating stage in a glove box to obtain a surface-modified and modified ZnO electron transport layer; 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 light-emitting layer; then fabricate TFB on the perovskite light-emitting layer to form a hole transport layer; finally, use tweezers to scrape off the edge part to expose the ITO cathode, and then place the device with multiple functional layers spin-coated face down into a fixed-pattern mask template, and evaporate the Au electrode by vacuum evaporation to obtain the PeLED device of the AEAPTMS group.

[0069] The above steps describe in detail the preparation process of each embodiment.

[0070] 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 and modified with an organosilane coupling agent capped with an amino group or a halogen. Figure 2 is a schematic diagram of the molecular structure of some organosilane coupling agents capped with an amino group or a halogen for example. As Figure 3 shown, the X group can hydrolyze to generate silanol (Si-OH) under the action of water, and then undergo a condensation reaction with the hydroxyl groups on the ZnO thin film surface to form a Si-O-Si network structure, and expose amino groups or halogen groups on the ZnO substrate surface. IPTMS and AEAPTMS both contain the same hydrolyzable group part, so we use AEAPTMS to explain the influence of the Si-O-Si network structure formed by hydrolysis and condensation on the thermal stability of the ZnO thin film and the perovskite thin film. As Figure 4From the X-ray photoelectron spectroscopy (XPS) analysis results shown below, we observed that a distinct Si 2p peak appeared near 103.5° in the ZnO film surface-modified with AEAPTMS, accompanied by the emergence of the Si-O-Si characteristic peak. This phenomenon indicates that hydrolysis and condensation reactions of AEAPTMS occurred successfully on the ZnO film surface, forming a stable inorganic silicon network structure. As Figure 5 shown in the X-ray photoelectron spectroscopy (XPS) analysis results below, we observed a significant decrease in the areas of the O OH characteristic peak at 532° and the O V characteristic peak at 531° in the ZnO film surface-modified with AEAPTMS. This phenomenon indicates that AEAPTMS can effectively eliminate hydroxyl groups and oxygen vacancies on the ZnO film surface. Figure 6 The XRD results of the perovskite film under continuous heating at 100 °C are shown below. The sample without AEAPTMS modification showed the characteristic peak of PbI2 after heating for 600 minutes, while the sample modified with AEAPTMS still exhibited the characteristic peaks of perovskite. This indicates that the formation of the Si-O-Si network structure can effectively inhibit the decomposition of perovskite by ZnO. Figure 7 The X-ray diffraction (XRD) spectra of perovskite in Figure 8 further confirmed the positive effects of AEAPTMS and IPTMS surface modifications on the ZnO film, that is, through this treatment, high-quality crystalline films of perovskite can be induced to form on the upper interface. However, the surface modification of ZnO film with BUTMS without amino or halogen capping did not show positive effects, and the corresponding perovskite film showed lower XRD characteristic peak intensities. Therefore, it is the amino or halogen end groups that bring this positive gain effect. As Figure 9 shown below, the PeLED devices fabricated using ZnO films surface-modified with AEAPTMS or IPTMS showed significant improvements in both external quantum efficiency (EQE) and radiance. Meanwhile, at a current density of 100 mA cm -2 , the T50 stability of the PeLED devices was significantly improved from 23.5 hours to 302 hours (IPTMS group) and 392 hours (AEAPTMS group). In summary, surface modification of ZnO films using organosilane coupling agents with amino or halogen capping can not only induce the formation of crystalline perovskite films with both high crystalline quality and excellent optoelectronic properties, but also the stable Si-O-Si network structure formed on the ZnO surface after hydrolysis and condensation can effectively slow down the continuous decomposition of the perovskite light-emitting layer by ZnO, ultimately achieving a significant improvement in the performance and stability of PeLED devices.

[0071] The present invention has been illustrated by the above embodiments. However, 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 stable perovskite light-emitting diode, characterized in that: It 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 which is surface-modified by an amino- or halogen-terminated organic silicon coupling agent.

2. The stable operation perovskite light emitting diode according to claim 1, characterized in that: The structural formula of the amino or halogen terminated organosilicon coupling agent is: Wherein, R is an amino group or a halogen group, and X is a hydrolyzable group.

3. The stable operation perovskite light emitting diode according to claim 1, characterized in that: The amino or halogen terminated silicone coupling agent is 3-(2-aminoethylamino)propyltrimethoxysilane, (3-iodopropyl)trimethoxysilane, 3-aminopropyltriethoxysilane, 3-aminopropyltriethoxysilane, 3-aminopropyltriethoxysilane, N1-(3-(trimethoxysilyl)propyl)ethane-1,2-diamine, N-methyl-3-aminopropyltrimethoxysilane, [3-(N,N-dimethylamino)propyl]trimethoxysilane, bis[3-(triethoxysilyl)propyl]amine, 3-bromopropyltrimethoxysilane, 3-chloropropyltrimethoxysilane or trifluoropropanetrimethoxysilane.

4. The stable operation 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 an amino- or halogen-terminated organosilicon coupling agent in a solvent to prepare a modified solution having a concentration of 0.01 to 50 mg / ml; (4) Dropping the modified liquid onto the ZnO film obtained in step 2, spin coating, and annealing to obtain a surface-modified ZnO electron transport layer.

5. The stable operation 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.

6. A method for preparing a stable perovskite light-emitting diode, characterized in that: The following steps are involved: Step 1. Solution preparation: Dispersing an amino- or halogen-terminated organosilicon coupling agent A in a solvent B to prepare a mixed solution C with a concentration of 0.01 to 50 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: Dropping the mixed solution C onto the ZnO film obtained in step 3, spin coating, and thermal annealing 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.

7. The method for preparing a stable perovskite light-emitting diode according to claim 6, 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 (1.5-5.0): 1: (0.1-1.5), mixing them evenly to obtain a mixed solution A; adding additive D to the mixed solution A, stirring and mixing evenly, stirring and reacting at a temperature of 50-90° C. 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.

8. The method for preparing a stable perovskite light-emitting diode according to claim 7, 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.

9. The method for preparing a stable perovskite light-emitting diode according to claim 6, characterized in that: In step 1.1, the amino- or halogen-terminated organosilicon coupling agent A is 3-(2-aminoethylamino)propyltrimethoxysilane, (3-iodopropyl)trimethoxysilane, 3-aminopropyltriethoxysilane, 3-aminopropyltriethoxysilane, 3-aminopropyltriethoxysilane, N1-(3-(trimethoxysilyl)propyl)ethane-1,2-diamine, N-methyl-3-aminopropyltrimethoxysilane, [3-(N,N-dimethylamino)propyl]trimethoxysilane, bis[3-(triethoxysilyl)propyl]amine, 3-bromopropyltrimethoxysilane, 3-chloropropyltrimethoxysilane or trifluoropropanetrimethoxysilane; the solvent B is ethanol, isopropanol or N,N-dimethylformamide.

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