Method for preparing flexible blue light calcium titanium light-emitting diode by regulating and controlling air through polymer

Abstract

The invention discloses a method for preparing a flexible blue light calcium titanium light-emitting diode by regulating and controlling air through a polymer, and belongs to the technical field of semiconductor device production. The nickel oxide (NiOx) transmission layer is modified through in-situ polymerization of bis (vinyl sulfuryl) methane (BVM) and pentaerythritol tetramercaptoacetate (PTMPA), the mechanical flexibility of the nickel oxide (NiOx) is effectively enhanced, perovskite thin film crystallization is regulated and controlled, and finally the flexible blue light perovskite light-emitting diode with the light-emitting wavelength being 488 nm is achieved.

Description

Technical Field

[0001] The present invention belongs to the technical field of semiconductor device production, and specifically relates to a method for preparing a flexible blue light perovskite light-emitting diode by regulating air with a polymer. Background Art

[0002] Light-emitting diodes constructed with metal halide perovskites as luminescent materials have become a hot topic in cutting-edge research due to their outstanding advantages such as high color purity, wide color gamut, and adjustable band gap. At the same time, perovskite materials have the characteristics of being prepared by low-temperature solutions. On the one hand, low-temperature processing can meet the requirements of low processing temperature (<120°C) for polymer flexible substrates (PET / PEN), and can keep the shape of the substrate from deformation after processing. On the other hand, solution processing can meet the requirements of large-area, roll-to-roll machine automated processing. Therefore, perovskite materials have a wide range of application scenarios in the field of flexible electronics. After nearly 10 years of development, the external quantum efficiency of flexible perovskite light-emitting diodes has made significant breakthroughs, and the device efficiency of blue light flexible perovskite light-emitting diodes has exceeded 15%. Achieving air preparation is key to the commercialization of perovskite light-emitting diodes. Studies have already achieved air preparation of perovskite light-emitting diodes on rigid substrates through buried interface regulation. However, to date, the preparation of flexible perovskite light-emitting diodes in an air environment has not been achieved. The main obstacle is that perovskite materials are very sensitive to water, and moisture in the air can greatly interfere with the kinetics of perovskite film nucleation and crystallization growth. At the same time, flexible polymer substrates are more susceptible to moisture adsorption, which affects the crystallization growth of perovskite, increases the defect concentration at the interface, and leads to carrier capture and reduced device performance. Therefore, it is more difficult to prepare perovskite films on flexible substrates in an air environment.

[0003] On the other hand, when flexible devices are bent and used, the upper side of each functional layer of the flexible device is subjected to tensile stress and the lower side is subjected to compressive stress. The tensile stress on the upper side causes surface cracks on the upper surface of the film along grain boundaries or existing defects, which becomes the starting point for further degradation of the flexible device. As the number of bends increases, the cracks further expand and become through-cracks. At the same time, due to the pressure on the lower surface, the mismatch in Young's modulus between the functional layers of the flexible device will cause delamination, resulting in interstitial cracks. The generation of these cracks will affect the charge transfer at the interface. Through-cracks may even provide a channel for electrons and holes to recombine in the non-perovskite layer, resulting in a short circuit, thus affecting the service life of the flexible device. Summary of the Invention

[0004] To address the issues mentioned in the background art, the present invention provides a method for preparing flexible blue perovskite light-emitting diodes by polymer-controlled air flow. Bis(vinylsulfone)methane (BVM) and pentaerythritol tetramercaptoacetate (PTMPA) are introduced into the lower interface of the flexible perovskite light-emitting layer, regulating its crystallization kinetics, enhancing the device's mechanical properties, and achieving flexible blue light emission. The preparation process is simple.

[0005] The first object of the present invention is to provide a method for preparing a flexible blue light-emitting perovskite diode by regulating air with a polymer, comprising the following steps:

[0006] Preparation of polymer solution: Under the protection of inert gas, dissolve bis(vinylsulfonyl)methane and pentaerythritol tetrathioglycolate in a certain proportion in a polar solvent dimethyl sulfoxide (DMSO) and allow to stand until fully dissolved to obtain a polymer precursor solution;

[0007] Preparation of perovskite light-emitting layer solution: Under inert gas protection, lead bromide (PbBr2), cesium bromide (CsBr) and phenylethylammonium bromide (PEABr) are dissolved in a polar solvent dimethyl sulfoxide (DMSO) at a certain molar ratio and stirred at 25°C for 24 hours to obtain the perovskite light-emitting layer solution;

[0008] Preparation of flexible perovskite blue light-emitting diodes in air: In an air environment, a hole transport layer nickel oxide (NiO) was spin-coated on a conductive polyethylene terephthalate (PET) indium tin oxide (ITO) substrate. x ) and annealing, followed by spin coating of a polymer precursor solution. During the annealing process, the molecules complete in situ cross-linking to form a polymer (poly-(BVM-PTMPA)). Subsequently, a perovskite precursor solution is spin-coated on the polymer layer. After heat treatment and annealing, a perovskite light-emitting film is formed. Finally, the prepared film is transferred to a glove box protected by inert gas to evaporate the electron transport layer and metal electrode to obtain a polymer-regulated flexible blue light-emitting perovskite diode.

[0009] Preferably, the purity of the bis(vinylsulfonyl)methane and pentaerythritol tetrathioglycolate is 99.99%, and the dimethyl sulfoxide (DMSO) is anhydrous ultra-dry grade.

[0010] Preferably, the hole transport layer is nickel oxide (NiO x ), firstly NiO x Disperse in deionized water to a concentration of 10 mg / mL. Ultrasonicate the solution for 0.5 h. Filter through a 0.22 μm PTFE filter before use. Spin coat at 4000 rpm / min for 40 seconds. After spin coating, quickly anneal on a 100°C hot plate for 10 minutes.

[0011] Preferably, the electron transport layer is TPBi with a thickness of 30 nm and a gas deposition rate of

[0012]

[0013] Preferably, the metal electrodes are lithium fluoride and metal aluminum, wherein the thickness of lithium fluoride is 1.5 nm and the thickness of aluminum is 50 nm. The evaporation rates of lithium fluoride and aluminum need to be controlled at and

[0014] Compared with the prior art, the present invention has the following advantages:

[0015] The method provided by the present invention for preparing flexible blue light perovskite light-emitting diodes by regulating air with polymers has a simple preparation method, short periodicity and good device repeatability, improves the bending performance of flexible devices, and realizes the batch air preparation of flexible blue light perovskite light-emitting diodes. BRIEF DESCRIPTION OF THE DRAWINGS

[0016] Figure 1 This is a schematic diagram of the structure of the flexible blue light emitting diode of the present invention.

[0017] Figure 2 These are comparison photos of the atomic force microscope morphology of the polymer-regulated hole transport layer prepared in Example 1.

[0018] Figure 3 These are comparison photos of the atomic force microscope morphology of the polymer-regulated perovskite light-emitting layer prepared in Example 1.

[0019] Figure 4 This is a curve diagram showing the relationship between voltage, current density and brightness of the flexible blue perovskite light-emitting diode prepared in Example 1.

[0020] Figure 5 This is a curve diagram showing the relationship between voltage and external quantum efficiency of the flexible blue light emitting diode prepared in Example 1.

[0021] Figure 6 This is the electroluminescence curve of the flexible blue perovskite light-emitting diode prepared in Example 1.

[0022] Figure 7 This is the external quantum efficiency decay curve of the flexible blue light emitting diode prepared in Example 1 under different bending times.

[0023] Description of reference numerals:

[0024] 1. Negative electrode; 2. Electron transport layer; 3. Perovskite light-emitting layer; 4. Hole transport layer and polymer layer; 5. Positive electrode ITO; 6. Polyethylene terephthalate. DETAILED DESCRIPTION

[0025] In order to enable those skilled in the art to better understand and implement the technical solution of the present invention, the present invention is further described below with reference to specific embodiments and drawings, but the embodiments are not intended to limit the present invention.

[0026] Figure 1 Schematic diagram of the structure of the flexible blue perovskite light-emitting diode prepared by the present invention, 1 is the negative electrode (metal aluminum and lithium fluoride); 2 is the electron transport layer (TPBi); 3 is the perovskite light-emitting layer; 4 is the hole material nickel oxide and polymer mixed layer; 5 is the positive electrode ITO; 6 is the polyethylene terephthalate (PET) substrate.

[0027] Example 1

[0028] A method for preparing a flexible blue light-emitting diode using polymer to control air is specifically carried out according to the following steps:

[0029] S1. Weigh 0.015M bis(vinylsulfonyl)methane and 0.014M pentaerythritol tetrathioglycolate into a 3mL white glass bottle, add 1mL of dimethyl sulfoxide (DMSO), and allow to stand until fully dissolved. During this period, observe the dissolution state of the molecules in the bottle. Shake the bottle to assist dissolution if necessary to obtain a polymer precursor solution. Dissolve lead bromide (PbBr2), cesium bromide (CsBr), and phenethylammonium bromide (PEABr) in the polar solvent dimethyl sulfoxide (DMSO) according to a certain molar ratio and stir at 25°C for 24 hours to obtain a perovskite light-emitting layer solution.

[0030] S2. Select a conductive polyethylene terephthalate (PET) indium tin oxide (ITO) substrate with a thickness of 0.125 mm and a transmittance of ~80%. Note that the flexible substrate needs to be ultrasonically cleaned with anhydrous ethanol solvent for ~1 hour before use. Store it in an ethanol solution until use, and use nitrogen to blow off the ethanol on the substrate surface.

[0031] S3. Plasma treatment was used to treat the substrate surface for 10 minutes to remove organic pollutants on the substrate surface and improve the wettability of the substrate surface. After treatment, nickel oxide (NiO) was prepared on the flexible substrate by spin coating in an air environment. x ) film (4000 rpm, 40 s). After spin coating, the film was quickly treated on a constant temperature hot stage at 100 °C for 10 min.

[0032] S4. After annealing, the polymer precursor solution was spin-coated onto nickel oxide (NiO x ) upper layer, spin coating time is 40s, after the spin coating is completed, quickly move to a constant temperature hot stage, anneal at 90℃ for 3min;

[0033] S5. After annealing, drop the perovskite precursor onto the polymer in air. Once the precursor has spread on the substrate, spin-coat the precursor at 3000 rpm for 70 seconds. After spin coating, transfer the film to a 70°C hot plate for 1 minute to obtain a flexible blue perovskite film.

[0034] S6. Transfer the prepared film to a glove box filled with an inert atmosphere. Use methanol to wipe off part of the film to expose the common electrode. Transfer the film to the evaporator and use a mechanical pump and a molecular pump to reduce the pressure in the chamber to 1×10 -5 Pa below, start evaporating the electron transport layer. The electron transport layer material is TPBi, with a thickness of 30nm, and the evaporation rate is controlled at

[0035] S7. After the TPBi evaporation of the electron transport layer is completed, lithium fluoride with a thickness of 1.5 nm is evaporated onto the electron transport layer. The evaporation rate is controlled at After replacing the mask of the evaporated metal electrode, Evaporate 50nm of metal aluminum electrode at a rate of

[0036] S8. Finally, the area covered by the transparent ITO electrode and the aluminum electrode represents the actual light-emitting area of the flexible device. The prepared flexible device is placed in an external quantum efficiency test system to test the performance of the polymer-controlled air-activated flexible blue perovskite light-emitting diode device.

[0037] In order to illustrate the surface morphology of the hole transport layer regulated by the polymer obtained by the preparation method provided by the present invention, the surface of the hole transport layer prepared in Example 1 was observed using an atomic force microscope. Figure 2 ,It can be seen from the figure that the surface roughness of nickel oxide is significantly reduced after regulation by polymer (poly-(BVM-PTMPA)).

[0038] In order to illustrate that the polymer obtained by the preparation method provided by the present invention has better crystallinity of the perovskite film, the surface of the hole transport layer prepared in Example 1 was observed using an atomic force microscope. Figure 3 As can be seen from the figure, the perovskite crystallinity is better and the film is smoother after being regulated by the polymer (poly-(BVM-PTMPA)).

[0039] In order to further illustrate the effect of the flexible perovskite blue light emitting diode prepared by the method for preparing a flexible blue light perovskite light emitting diode by polymer-controlled air provided by the present invention, only the relevant performance of the flexible blue light perovskite light emitting diode prepared by polymer-controlled air provided in Example 1 was tested, and the test data is shown in FIG. Figures 4 to 7 ;

[0040] Figure 4 The graph shows the relationship between voltage, current density and brightness of the flexible blue perovskite light-emitting diode prepared in Example 1. It can be seen from the graph that the current density of the flexible device controlled by the polymer is significantly reduced, and the maximum luminous brightness can reach 258 cdm -2 ;

[0041] Figure 5 The relationship between voltage and external quantum efficiency of the flexible blue perovskite light-emitting diode prepared in Example 1 shows that the maximum external quantum efficiency can reach 1.32% after polymer regulation.

[0042] Figure 6 This is an electroluminescence curve of the flexible blue perovskite light-emitting diode prepared in Example 1, with a light emission wavelength at 488 nm;

[0043] Figure 7 The external quantum efficiency decay curve of the flexible blue perovskite light-emitting diode prepared in Example 1 under different bending times is shown in the figure. It can be seen that after 2000 bending times, it can still maintain 80% of the initial efficiency through polymer regulation;

[0044] from Figures 4 to 7 It can be seen that the flexible blue light perovskite light-emitting diode provided in Example 1 can achieve blue light emission at 488nm and has a long bending service life, indicating that the polymer successfully regulates the mechanical flexibility of the nickel oxide hole transport layer and the crystallinity of the perovskite film, realizing the preparation of flexible blue light perovskite diodes in air.

[0045] Obviously, those skilled in the art may make various changes and modifications to the present invention without departing from the spirit and scope of the present invention. Thus, if such changes and modifications of the present invention fall within the scope of the claims and their equivalents, such changes and modifications are intended to be included.

Claims

1. A method for preparing flexible blue light-emitting diodes by regulating air with polymers, characterized in that: The following steps are involved: Preparation of polymer solution: Under inert gas protection, bis(vinylsulfone)methane (BVM) and pentaerythritol tetramercaptoacetate (PTMPA) are dissolved and dispersed in a polar solvent dimethyl sulfoxide (DMSO) in a certain proportion, and allowed to stand until fully dissolved to obtain a polymer precursor solution; Preparation of perovskite light-emitting layer solution: Under inert gas protection, lead bromide (PbBr2), cesium bromide (CsBr) and phenylethylammonium bromide (PEABr) are dissolved in a polar solvent dimethyl sulfoxide (DMSO) at a certain molar ratio and stirred at 25°C for 24 hours to obtain the perovskite light-emitting layer solution; Air preparation of flexible perovskite blue light-emitting diodes: In an air environment, a hole transport layer of nickel oxide (NiOx) is spin-coated on a conductive polyethylene terephthalate (PET) indium tin oxide (ITO) substrate and annealed, followed by spin-coating a polymer precursor solution. During the annealing process, the molecules complete in situ cross-linking to form a polymer (poly-(BVM-PTMPA)). Subsequently, a perovskite precursor solution is spin-coated on the polymer layer. After heat treatment and annealing, a perovskite light-emitting film is formed. Finally, the prepared film is transferred to a glove box filled with inert gas protection to evaporate the electron transport layer and metal electrode to obtain a polymer-regulated flexible blue light-emitting perovskite diode. Wherein, in the polymer precursor solution, the molar concentration of bis(vinylsulfone)methane is 0.015M, and the molar concentration of pentaerythritol tetrathioglycolate is 0.014M.

2. The method for preparing flexible blue light-emitting diodes by polymer-controlled air according to claim 1, characterized in that: The polymer film is prepared by the spin coating method according to the following steps: dissolving bis(vinylsulfone)methane and pentaerythritol tetrathioglycolate in dimethyl sulfoxide (DMSO) solvent according to the above molar concentration, and standing for sufficient dissolution; then dropping the polymer precursor solution onto the hole transport layer (NiO x ) and spin-coated at 4000 rpm / min for 40 s. After the spin coating is completed, the film is quickly transferred to a constant temperature hot stage at 90°C and annealed for 3 min to complete in situ cross-linking to form a polymer film.

3. The method for preparing flexible blue light emitting diodes by polymer air regulation according to claim 1, characterized in that: The flexible blue perovskite film was prepared in an air environment. The spin coating speed was set at 3000 rpm / min and the spin coating process lasted for 70 seconds. After the spin coating was completed, the film was transferred to a 70°C constant temperature hot plate for treatment for 1 minute to obtain a flexible blue perovskite film with a luminescence peak at around 484 nm.

4. The method for preparing flexible blue light-emitting diodes by polymer-controlled air according to claim 1, characterized in that: The hole transport layer is NiO x , NiO x Dissolve in deionized water to prepare a 10 mg / mL solution, and spin-coat at a speed of 4000 rpm / min.

5. The method for preparing flexible blue light emitting diodes by polymer air regulation according to claim 1, characterized in that: The thickness of the electron transport layer TPBi is 30 nm.

6. The method for preparing flexible blue light-emitting diodes by polymer-controlled air according to claim 1, characterized in that: The metal electrode is aluminum and has a thickness of 50 nm.

7. The method for preparing flexible blue light-emitting diodes by polymer-controlled air according to claim 1, characterized in that: The conductive polyethylene terephthalate indium tin oxide substrate has a sheet resistance of 15Ω.

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