Preparation method of three-dimensional blue-light perovskite thin film and preparation method of light-emitting diode thereof

Abstract

The invention discloses a preparation method of a three-dimensional blue-light perovskite thin film and a light-emitting diode thereof. The preparation method comprises the following steps: preparing a perovskite precursor solution, selecting ITO as a conductive substrate, spin-coating a PEDOT: PSS solution on the ITO conductive substrate, and carrying out annealing treatment to form a hole transport layer; spin-coating a perovskite precursor solution, and carrying out annealing treatment to prepare a three-dimensional halogen-mixed perovskite thin film as a perovskite light-emitting layer; carrying out vacuum thermal evaporation on TPBi to form an electron transport layer; performing vacuum thermal evaporation on lithium fluoride to form a cathode modification layer; and carrying out vacuum thermal evaporation on a metal aluminum electrode on the cathode modification layer to obtain the light-emitting diode of the three-dimensional halogen-mixed blue-light perovskite thin film. According to the preparation method of the light-emitting diode of the three-dimensional halogen-mixed blue-light perovskite thin film, trimethyl cyanurate is introduced into a three-dimensional halogen-mixed perovskite precursor solution, internal defects of perovskite are passivated, non-radiative recombination is inhibited, and the device has excellent charge transmission performance and good device performance.

Description

Technical Field

[0001] The present invention relates to the field of diodes, and in particular to a method for preparing a three-dimensional blue perovskite film and a light-emitting diode thereof. Background Art

[0002] Metal halide perovskites (MHPs) offer a new path forward for light-emitting diode (LED) technology thanks to their solution processability, bandgap tunability, and excellent optical properties. Perovskite light-emitting diodes (PeLEDs) have developed rapidly since their initial publication in 2014, with their EQE increasing by over 200-fold in the primary emission band, setting a new record for efficiency gains in optoelectronic materials. Over the past decade, the development of metal halide perovskite LEDs has been rapid, with their near-infrared external quantum efficiency increasing from less than 0.1% to 30%, and visible red and green to over 30%. However, the performance of blue PeLEDs, one of the three primary colors, still lags behind other colors, becoming a key bottleneck restricting full-color display applications.

[0003] By adjusting the ratio of halogen atoms, the spectrum can be modulated to the blue band. However, the deeper valence band energy levels of blue perovskites significantly increase the hole injection barrier, leading to unbalanced carrier injection. In addition, the rapid crystallization process leads to a large number of holes in the film, resulting in severe device leakage current and suppressing the performance of perovskite light-emitting diodes. Summary of the Invention

[0004] In view of the above-mentioned defects of the prior art, the technical problem to be solved by the present invention is to solve the problems of induced non-radiative recombination, unbalanced carrier injection, and severe leakage of devices caused by a large number of thin film holes in the existing light-emitting diodes. The present invention provides a three-dimensional blue perovskite film and a method for preparing the same. By introducing trimethyl cyanurate into the three-dimensional mixed halogen perovskite precursor solution, the COC in TMC can react with the uncoordinated Pb 2+ Combined with the above, the internal defects of the perovskite are passivated and non-radiative recombination is suppressed, which makes the device have excellent charge transport properties and better device performance.

[0005] To achieve the above objectives, the present invention provides a method for preparing a three-dimensional mixed-halogen blue perovskite film, comprising the following steps:

[0006] preparing a perovskite precursor solution by blending cesium bromide, lead bromide, lead chloride, cesium chloride, and cesium trifluoroacetate powders, then dropwise adding dimethyl sulfoxide solvent, and subsequently adding 1 mg / mL, 2 mg / mL, and 3 mg / mL of trimethyl cyanurate powder to the solution, respectively, to form three perovskite precursor solutions with different additive concentrations;

[0007] ITO was selected as the conductive substrate, and a PEDOT:PSS solution was spin-coated on the ITO conductive substrate and annealed to form a hole transport layer;

[0008] The perovskite precursor solution is spin-coated on the hole transport layer and annealed to prepare a three-dimensional mixed-halogen perovskite film.

[0009] Another embodiment of the present invention provides a method for preparing a three-dimensional mixed-halogen blue perovskite light-emitting diode, comprising the following steps:

[0010] TPBi was vacuum-evaporated on the three-dimensional mixed-halogen perovskite film to form an electron transport layer;

[0011] Vacuum thermal evaporation of lithium fluoride on the electron transport layer to form a cathode modification layer;

[0012] A metal aluminum electrode was vacuum thermally evaporated on the cathode modification layer to obtain a three-dimensional mixed halogen blue light perovskite light-emitting diode.

[0013] Furthermore, the concentration of trimethyl cyanurate in the perovskite precursor solution is 1 to 3 mg / mL.

[0014] Furthermore, the masses of cesium bromide, lead bromide, lead chloride, cesium chloride, and cesium trifluoroacetate powders are 45.1 mg of cesium bromide, 38.9 mg of lead bromide, 29.5 mg of lead chloride, 6.7 mg of cesium chloride, and 24.6 mg of cesium trifluoroacetate powder, respectively.

[0015] Furthermore, the rotation speed of spin coating the perovskite precursor solution is 3000-4000 rpm, and the spin coating time is 50-60 s; the temperature of annealing treatment after spin coating the perovskite precursor solution is 60-80° C., and the time is 5-10 min.

[0016] Furthermore, a PEDOT:PSS solution is spin-coated on the ITO conductive substrate at a spin-coating speed of 3500-4000 rpm for 40-50 seconds, and annealing is performed after spin-coating at a temperature of 120-150° C. for 5-20 minutes.

[0017] Furthermore, TPBi is vacuum-evaporated on the perovskite light-emitting layer to form an electron transport layer, wherein the evaporated thickness of TPBi is 30-40 nm.

[0018] Furthermore, lithium fluoride is vacuum thermally evaporated on the electron transport layer to form a cathode modification layer, wherein the evaporated thickness of the lithium fluoride is 0.5 to 1 nm.

[0019] Furthermore, a metal aluminum electrode is vacuum thermally evaporated on the cathode modification layer, wherein the evaporated thickness of the metal aluminum is 80-100 nm.

[0020] Furthermore, ITO is selected as the conductive substrate, and a cleaning process is also included, in which glass cleaning agent, deionized water, acetone and isopropyl alcohol are used for cleaning in sequence.

[0021] Technical Effects

[0022] The present invention discloses a three-dimensional blue perovskite film and a method for preparing a light-emitting diode thereof. In the prepared light-emitting diode, the perovskite light-emitting layer is optimized by trimethyl cyanurate, so that the valence band of the perovskite layer is shifted upward, the hole injection barrier is reduced, and the enhanced hole injection is beneficial to improving the photoelectric performance of the perovskite light-emitting diode, including PL intensity, device brightness, and external quantum efficiency. The maximum brightness of the perovskite light-emitting diode is 3527cd / m 2 , the maximum EQE is 10.4%; (3) The preparation method of the perovskite light-emitting diode is simple and efficient.

[0023] The concept, specific structure and technical effects of the present invention will be further described below in conjunction with the accompanying drawings to fully understand the purpose, characteristics and effects of the present invention. BRIEF DESCRIPTION OF THE DRAWINGS

[0024] Figure 1 This is a schematic structural diagram of a three-dimensional mixed halogen blue perovskite light-emitting diode according to a preferred embodiment of the present invention;

[0025] Figure 2 is a photoluminescence (PL) graph of the perovskite films of Examples 1 to 3 and Comparative Example 1;

[0026] Figure 3 are scanning electron microscope (SEM) images of the perovskite films of Example 2 and Comparative Example 1;

[0027] Figure 4 1 is an electroluminescence (EL) curve of the perovskite light-emitting diode device of Example 2 and Comparative Example 1;

[0028] Figure 5 2 is a current density-voltage (JV) diagram of the perovskite light-emitting diode devices of Example 2 and Comparative Example 1;

[0029] Figure 6 is a brightness-voltage (LV) graph of the perovskite light-emitting diode devices of Example 2 and Comparative Example 1;

[0030] Figure 7 2 is an external quantum efficiency-voltage (EQE-V) diagram of the perovskite light-emitting diode devices of Example 2 and Comparative Example 1. DETAILED DESCRIPTION

[0031] In order to make the technical problems, technical solutions and beneficial effects to be solved by the present invention more clearly understood, the present invention is further described in detail below with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are only used to explain the present invention and are not intended to limit the present invention.

[0032] In the following description, specific details, such as certain internal procedures and techniques, are provided for purposes of illustration and not limitation to facilitate a thorough understanding of the embodiments of the present invention. However, it will be apparent to those skilled in the art that the present invention may be practiced in other embodiments without these specific details. In other cases, detailed descriptions of well-known systems, devices, circuits, and methods are omitted so as not to obscure the description of the present invention with unnecessary detail.

[0033] like Figure 1 As shown, the present invention provides a three-dimensional mixed-halogen blue perovskite light-emitting diode, which comprises, in order, a conductive substrate layer, a hole transport layer, a trimethyl cyanurate-passivated perovskite light-emitting layer, an electron transport layer, a cathode modification layer, and a metal aluminum electrode. The trimethyl cyanurate-passivated perovskite light-emitting layer is formed by spin-coating a precursor solution doped with trimethyl cyanurate at a concentration of 1 to 3 mg / mL, followed by annealing.

[0034] The present invention discloses a three-dimensional mixed halogen blue light perovskite light-emitting diode, wherein the hole transport layer is used to promote hole injection into the light-emitting layer; the perovskite light-emitting layer passivated with trimethyl cyanurate will recombine electrons from the hole transport layer and the electron transport layer under a certain bias voltage to thereby emit light, and the perovskite passivated with trimethyl cyanurate can enhance carrier radiative recombination, thereby improving device performance; the electron transport layer is used to transport electrons and block excess holes, thereby preventing charge accumulation from corroding the cathode and affecting the device life; the cathode modification layer is used to adjust the energy level of the metal electrode aluminum and reduce damage to the perovskite film during the metal evaporation process; after a certain voltage is applied to the aluminum electrode and the conductive substrate, a closed loop is formed and the device emits light when a certain voltage is reached.

[0035] The three-dimensional mixed-halogen blue perovskite LED of this invention operates under a certain bias voltage. Holes from the anode and electrons from the cathode recombine in the perovskite light-emitting layer to form excitons. The excitons then return to their ground state through radiation, emitting photons and producing light. Compared to traditional all-inorganic LEDs, perovskite LEDs can be prepared in solution, have lower production costs, and are rapidly developing.

[0036] The luminescence principle of the three-dimensional mixed-halogen blue perovskite film and its light-emitting diode of the present invention is as follows: under a certain bias voltage, holes from the anode and electrons from the cathode recombine in the perovskite light-emitting layer to form excitons. The excitons return to the ground state through radiation, thereby radiating photons to achieve luminescence. The intensity of the radiant luminescence depends on the degree of exciton recombination in the perovskite layer. Traditional films spin-coated from a CsPb(Br / Cl)3 precursor solution have a deep perovskite energy level, which causes holes to accumulate in the hole transport layer, making hole injection difficult. In addition, films that form rapidly have more holes, which reduces the luminescence performance of PeLEDs.

[0037] The present invention provides a method for preparing a three-dimensional mixed-halogen blue light perovskite film, comprising the following steps:

[0038] The perovskite precursor solution is prepared by blending cesium bromide, lead bromide, lead chloride, cesium chloride, and cesium trifluoroacetate powders, then dripping dimethyl sulfoxide solvent, and simultaneously adding trimethyl cyanurate powder to dissolve in the above solution to form three concentrations of perovskite precursor solutions respectively; the perovskite precursor solution doped with trimethyl cyanurate is spin-coated at a rotation speed of 3000 to 4000 rpm and a spin-coating time of 50 to 60 seconds. The spin-coating speed affects the thickness of the perovskite film, and the spin-coating time is selected to allow the solvent to fully evaporate; the annealing temperature is 60 to 80°C and the time is 5 to 10 minutes. The annealing temperature and time affect the crystallization of the perovskite and can also volatilize excess solvent.

[0039] The ITO substrate was used as a conductive substrate. A PEDOT:PSS solution was spin-coated onto the substrate and annealed to form a hole transport layer. PEDOT:PSS (poly(3,4-ethylenedioxythiophene):poly(4-styrenesulfonic acid)) was spin-coated at a speed of 3500-4000 rpm for 40-50 seconds and annealed at a temperature of 120-150°C for 15-20 minutes. The spin-coating process was performed in a glove box, where the water and oxygen content was maintained below 0.1 ppm. The ITO substrate was also cleaned using ultrasonic cleaning with glass detergent, deionized water, acetone, and isopropyl alcohol, in sequence. This was done to remove organic and inorganic impurities adhering to the substrate surface, facilitating the subsequent formation of high-quality thin films.

[0040] On the hole transport layer, a perovskite precursor solution is spin-coated and annealed to prepare a three-dimensional mixed-halogen perovskite film as a perovskite light-emitting layer.

[0041] The present invention provides a method for preparing a three-dimensional mixed halogen blue perovskite light-emitting diode, comprising the following steps:

[0042] TPBi is vacuum-evaporated on a three-dimensional mixed-halogen perovskite film to form an electron transport layer; the Chinese name of TPBi is 1,3,5-tris(1-phenyl-1H-benzimidazol-2-yl)benzene; the thickness of TPBi is 30 to 40 nm.

[0043] Lithium fluoride is vacuum-evaporated on the electron transport layer to form a cathode modification layer; the thickness of the lithium fluoride is 0.5 to 1 nm.

[0044] A metal aluminum electrode is vacuum-evaporated on the cathode modification layer to obtain a three-dimensional mixed-halogen blue perovskite light-emitting diode; the thickness of the metal aluminum is 80 to 110 nm.

[0045] The technical solution of the present invention will be further described below in conjunction with embodiments.

[0046] Example 1

[0047] The perovskite film and light-emitting diode thereof passivated by trimethyl cyanurate of the present invention, and the preparation method thereof comprise the following steps:

[0048] (1) The ITO substrate was cleaned of surface impurities with glass cleaning agent in sequence, and ultrasonically cleaned with deionized water, acetone, and isopropyl alcohol for 15 minutes, and then dried and decontaminated with ultraviolet light in a drying oven for 15 minutes;

[0049] (2) Spin coating a PEDOT:PSS solution on a clean ITO substrate at a speed of 3500 rpm for 50 s. After the spin coating is completed, annealing is performed on a heating table at 120°C for 20 min to form a hole transport layer; 1 mL of the PEDOT:PSS solution is taken out and filtered using a polytetrafluoroethylene filter with a pore size of no more than 0.45 μm to remove impurities;

[0050] (3) On the hole transport layer, a precursor solution of trimethyl cyanurate with 1 mg / mL was spin-coated at 3000 rpm for 40 s. After the spin coating was completed, the film was annealed at 80°C for 5 min. At this time, the ITO turned blue under ultraviolet light, and a perovskite film was obtained.

[0051] (4) Depositing 40 nm of TPBi on the surface of the perovskite film using a vacuum thermal evaporation device to form an electron transport layer;

[0052] (5) On the electron transport layer, 1 nm of LiF was deposited using a vacuum thermal evaporation apparatus to form a cathode modification layer;

[0053] (6) On the cathode modification layer, an Al electrode with a thickness of about 100 nm was deposited using a vacuum thermal evaporation apparatus, and the entire device structure ITO / PEDOT:PSS / Perovskite / TPBi / LiF / Al was completed.

[0054] The required chemical materials include: cesium bromide (99.999%, CsBr), lead bromide (99.999%, PbBr2), lead chloride (99.999%, PbCl2), cesium chloride (CsCl), cesium trifluoroacetate (CsTFA), trimethylcyanurate, methyl sulfoxide (99.9%, DMSO), poly(4-styrenesulfonic acid) (PEDOT:PSS) 1,3,5-tris(1-phenyl-1H-benzimidazol-2-yl)benzene (TPBi), lithium fluoride (LiF), ITO substrate, and aluminum (Al) metal particles.

[0055] Preparation of perovskite precursor solution: Use a balance to weigh 45.1 mg of cesium bromide (CsBr), 38.9 mg of lead bromide (PbBr2), 29.5 mg of lead chloride (PbCl2), 6.7 mg of cesium chloride (CsCl) and 24.6 mg of cesium trifluoroacetate (CsTFA) powder, add 1.5 mL of dimethyl sulfoxide (DMSO) solvent, and dissolve 1 mg / mL of trimethyl cyanurate powder in the above solution. Heat and stir at a constant temperature of 60°C until the powder is completely dissolved and the solution becomes colorless and transparent.

[0056] Example 2

[0057] The perovskite film and light-emitting diode thereof passivated by trimethyl cyanurate of the present invention, and the preparation method thereof comprise the following steps:

[0058] (1) The ITO substrate was cleaned of surface impurities with glass cleaning agent in sequence, and ultrasonically cleaned with deionized water, acetone, and isopropyl alcohol for 15 minutes, and then dried and decontaminated with ultraviolet light in a drying oven for 15 minutes;

[0059] (2) Spin coating a PEDOT:PSS solvent on a clean ITO substrate at a speed of 4000 rpm for 40 s. After the spin coating is completed, annealing is performed on a heating plate at 120°C for 20 min to form a hole transport layer; 1 mL of the PEDOT:PSS solution is taken out and filtered using a polytetrafluoroethylene filter with a pore size of no more than 0.45 μm to remove impurities;

[0060] (3) On the hole transport layer, a precursor solution of trimethyl cyanurate with 2 mg / ml was spin-coated at 3000 rpm for 40 s. After the spin coating was completed, the film was annealed at 80°C for 5 min. At this time, the ITO turned blue under ultraviolet light, and a perovskite film was obtained.

[0061] (4) Depositing 40 nm of TPBi on the surface of the perovskite film using a vacuum thermal evaporation device to form an electron transport layer;

[0062] (5) On the electron transport layer, 1 nm of LiF was deposited using a vacuum thermal evaporation apparatus to form a cathode modification layer;

[0063] (6) On the cathode modification layer, an Al electrode with a thickness of about 100 nm was deposited using a vacuum thermal evaporation apparatus, and the entire device structure ITO / PEDOT:PSS / Perovskite / TPBi / LiF / Al was completed.

[0064] Preparation of perovskite solution: The preparation method is the same as that in Example 1, and the concentration of trimethyl cyanurate powder is 2 mg / mL.

[0065] Example 3

[0066] The perovskite film and light-emitting diode thereof passivated by trimethyl cyanurate of the present invention, and the preparation method thereof comprise the following steps:

[0067] (1) The ITO substrate was cleaned of surface impurities with glass cleaning agent in sequence, and ultrasonically cleaned with deionized water, acetone, and isopropyl alcohol for 15 minutes, and then dried and decontaminated with ultraviolet light in a drying oven for 15 minutes;

[0068] (2) Spin coating a PEDOT:PSS solvent on a clean ITO substrate at a speed of 4000 rpm for 40 s. After the spin coating is completed, annealing is performed on a heating plate at 120°C for 20 min to form a hole transport layer; 1 ml of the PEDOT:PSS solution is taken out and filtered using a polytetrafluoroethylene filter with a pore size of no more than 0.45 μm to remove impurities;

[0069] (3) On the hole transport layer, a precursor solution of trimethyl cyanurate with 3 mg / ml was spin-coated at 3000 rpm for 40 s. After the spin coating was completed, the film was annealed at 80°C for 5 min. At this time, the ITO turned blue under ultraviolet light, and a perovskite film was obtained.

[0070] (4) Depositing 40 nm of TPBi on the surface of the perovskite film using a vacuum thermal evaporation device to form an electron transport layer;

[0071] (5) On the electron transport layer, 1 nm of LiF was deposited using a vacuum thermal evaporation apparatus to form a cathode modification layer;

[0072] (6) On the cathode modification layer, an Al electrode with a thickness of about 100 nm was deposited using a vacuum thermal evaporation apparatus, and the entire device structure ITO / TFB:PVK / Perovskite / TPBi / LiF / Al was completed.

[0073] Preparation of perovskite solution: The preparation method is the same as that in Example 1, and the concentration of trimethyl cyanurate powder is 3 mg / ml.

[0074] Comparative Example 1

[0075] On the basis of Example 2, trimethyl cyanurate was not added to the precursor solution, and other conditions remained unchanged.

[0076] Performance Testing

[0077] The test results of each embodiment and comparative example are as follows Figure 2-7 shown.

[0078] The photoluminescence intensity of the blue perovskite films of Example 1, Example 2, Example 3 and Comparative Example 1 was tested to obtain a photoluminescence intensity-wavelength graph, as shown in FIG. Figure 2 As shown. Figure 2 It can be seen that when the concentration of trimethyl cyanurate is 1 mg / mL, 2 mg / mL and 3 mg / mL, the PL intensity of the device is enhanced. Among them, when the concentration is 2 mg / mL, the PL intensity of the sample is the strongest. When the concentration of trimethyl cyanurate is further increased to 3 mg / mL, the PL intensity begins to decrease.

[0079] The blue light perovskite films of Example 2 and Comparative Example 1 were tested by scanning electron microscope, and the SEM images of the perovskite films were obtained. Figure 3 As shown. Figure 3 It can be seen that trimethyl cyanurate can affect the surface coverage of the perovskite film. The quality of the film is better after adding trimethyl cyanurate, which means that the injection of holes is enhanced. The charges will not directly contact between the transport layers, nor will they cause accumulation and corrosion of the electrodes. Instead, more charges will be injected into the perovskite light-emitting layer, thereby improving the PL intensity of the perovskite film.

[0080] The electroluminescence test of the perovskite light-emitting diodes of Example 2 and Comparative Example 1 was carried out to obtain electroluminescence spectra, as shown in FIG. Figure 4 As shown. Figure 4 It can be seen that the emission peaks are all located at 484 nm. The intensity of the EL spectrum of the perovskite light-emitting diode with trimethyl cyanurate added in Example 2 is much higher than that in Comparative Example 1, indicating that the perovskite light-emitting diode with the addition of trimethyl cyanurate improves carrier recombination and enhances hole injection, thereby improving the EL intensity of the perovskite light-emitting diode.

[0081] The performance of the perovskite light emitting diode devices of Example 2 and Comparative Example 1 was tested. Figure 5 , Figure 6 , Figure 7 As shown in the current density-voltage diagram ( Figure 5) It can be seen that before 6 V, the perovskite light-emitting diode of Comparative Example 1 has a higher current density, which is due to its lower surface coverage. This also shows that adding trimethyl cyanurate to the precursor solution can effectively increase the surface coverage of the film, thereby improving the basic electrical performance of the device.

[0082] From the brightness-voltage diagram ( Figure 6 ) It can be seen that the maximum brightness of the perovskite light-emitting diodes of Example 2 and Comparative Example 1 is 3527 cd / m 2 and 1566cd / m 2 The brightness of the former is much higher than that of the latter. This is because the trimethyl cyanurate added to the perovskite light-emitting diode of Example 2 improves the recombination of carriers and enhances the injection of holes. More electrons from holes and electron transport layers are recombined in the perovskite light-emitting layer, and photons are emitted under a certain voltage, thereby improving the brightness. It can show higher brightness at a lower current density, which is more meaningful for the long-term and stable use of the light-emitting diode.

[0083] EQE-voltage diagram( Figure 7 ) also indicates that the passivation agent trimethyl cyanurate played a role. The maximum EQE of the device based on trimethyl cyanurate passivation was 10.4%, more than double the EQE of the control device (the maximum EQE of the control device was 5.7%). For light-emitting diodes, the external quantum efficiency is equal to the ratio of the number of photons emitted per unit time to the number of electron-hole pairs injected per unit time. A higher external quantum efficiency indicates a greater number of electron-hole pairs recombining per unit time, which is attributed to the improved quality of the perovskite film.

[0084] In the present invention, trimethyl cyanurate is doped into the perovskite precursor solution to improve the density of the perovskite film, thereby improving the recombination of carriers and improving the photoelectric properties of the device. The basic structural formula of the perovskite material is ABX3, where A represents an organic or inorganic monovalent ion, such as Cs + , Rb + 、MA + , FA + ; B represents a divalent metal cation, typically Pb 2+ 、Mn 2+ ; X represents a halide ion, such as I - Br - 、Cl -etc. The structure of trimethyl cyanurate contains three ester groups, which can in situ passivate the defect states of the perovskite film, improve the recombination of carriers, and reduce the degradation of the perovskite film. Moreover, the addition of trimethyl cyanurate does not affect the emission peak position of the perovskite light-emitting diode. By optimizing the concentration of the precursor solution doped with trimethyl cyanurate, under the passivation effect of trimethyl cyanurate at an optimized concentration (2 mg / mL), the morphology and crystallinity of the perovskite film are significantly improved, which is manifested in the reduction of grain boundary defects. Moreover, under a certain bias voltage, the carrier extraction and charge transfer are accelerated, the recombination of electron-hole pairs in the perovskite film is promoted, and the radiation coincidence efficiency is improved. The results show that the efficiency and stability of the device have been improved to a certain extent.

[0085] The above describes in detail the preferred embodiments of the present invention. It should be understood that those skilled in the art can make numerous modifications and variations based on the concepts of the present invention without inventive effort. Therefore, any technical solutions that can be derived by those skilled in the art through logical analysis, reasoning, or limited experimentation based on the concepts of the present invention and the prior art should be within the scope of protection defined by the claims.

Claims

1. A method for preparing a three-dimensional mixed halogen blue perovskite film, characterized in that: The following steps are involved: preparing a perovskite precursor solution by blending cesium bromide, lead bromide, lead chloride, cesium chloride, and cesium trifluoroacetate powders, then dropwise adding dimethyl sulfoxide solvent, and subsequently adding 1 mg / mL, 2 mg / mL, and 3 mg / mL of trimethyl cyanurate powder to the solution, respectively, to form three perovskite precursor solutions with different additive concentrations; ITO was selected as the conductive substrate, and a PEDOT:PSS solution was spin-coated on the ITO conductive substrate and annealed to form a hole transport layer; The perovskite precursor solution is spin-coated on the hole transport layer and annealed to prepare a three-dimensional mixed-halogen perovskite film.

2. A method for preparing a three-dimensional mixed halogen blue perovskite light-emitting diode, characterized in that: TPBi is vacuum-evaporated onto the three-dimensional mixed-halogen perovskite film to form an electron transport layer; Vacuum thermal evaporation of lithium fluoride on the electron transport layer to form a cathode modification layer; A metal aluminum electrode is vacuum thermally evaporated on the cathode modification layer to obtain a three-dimensional mixed halogen blue light perovskite film light-emitting diode.

3. The method for preparing a three-dimensional mixed-halogen blue perovskite film according to claim 1, wherein: 45.1 mg of cesium bromide, 38.9 mg of lead bromide, 29.5 mg of lead chloride, 6.7 mg of cesium chloride and 24.6 mg of cesium trifluoroacetate powder were dissolved in dimethyl sulfoxide solvent respectively. The concentration of trimethyl cyanurate in the perovskite precursor solution was 1-3 mg / mL. The PEDOT:PSS solution was spin-coated on the ITO conductive substrate at a speed of 3500-4000 rpm for 40-50 seconds. After spin-coating, annealing was performed at a temperature of 120-150°C for 5-20 minutes. The perovskite precursor solution was then spin-coated at a speed of 3000-4000 rpm for 50-60 seconds. The annealing temperature after spin coating the perovskite precursor solution is 60-80° C. and the time is 5-10 minutes.

4. The method for preparing a three-dimensional mixed halogen blue perovskite light-emitting diode according to claim 1, wherein: The masses of cesium bromide, lead bromide, lead chloride, cesium chloride, and cesium trifluoroacetate powders are 45.1 mg of cesium bromide, 38.9 mg of lead bromide, 29.5 mg of lead chloride, 6.7 mg of cesium chloride, and 24.6 mg of cesium trifluoroacetate powder, respectively.

5. The method for preparing a three-dimensional mixed halogen blue perovskite light-emitting diode according to claim 1, wherein: The PEDOT:PSS solution is spin-coated on the ITO conductive substrate at a spin-coating speed of 3500-4000 rpm for 40-50 seconds. After spin-coating, annealing is performed at a temperature of 120-150° C. for 5-20 minutes.

6. The method for preparing a three-dimensional mixed halogen blue perovskite light-emitting diode according to claim 1, wherein: The rotation speed of spin coating the perovskite precursor solution is 3000-4000 rpm, and the spin coating time is 50-60 seconds. The temperature of annealing treatment after spin coating the perovskite precursor solution is 60-80° C., and the time is 5-10 minutes.

7. The method for preparing a three-dimensional mixed halogen blue perovskite light-emitting diode according to claim 1, wherein: TPBi is vacuum thermally evaporated on the perovskite light-emitting layer to form an electron transport layer, wherein the evaporated thickness of TPBi is 30 to 40 nm.

8. The method for preparing a three-dimensional mixed halogen blue perovskite light-emitting diode according to claim 1, wherein: Lithium fluoride is vacuum thermally evaporated on the electron transport layer to form a cathode modification layer, wherein the evaporated thickness of the lithium fluoride is 0.5 to 1 nm.

9. The method for preparing a three-dimensional mixed halogen blue perovskite light-emitting diode according to claim 1, wherein: A metal aluminum electrode is vacuum thermally evaporated on the cathode modification layer, wherein the evaporation thickness of the metal aluminum is 80 to 100 nm.

10. The method for preparing a three-dimensional mixed halogen blue perovskite film and a light-emitting diode thereof according to claim 1, wherein: ITO was selected as the conductive substrate, and a cleaning process was also included, in which glass cleaner, deionized water, acetone, and isopropyl alcohol were used for cleaning in sequence.

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