A red light perovskite light-emitting material, a preparation method and a light-emitting diode device

Abstract

This invention relates to luminescent materials, specifically to a red-light perovskite luminescent material, its preparation method, and a light-emitting diode device. The red-light perovskite luminescent material comprises an iodine-based perovskite, wherein the iodine-based perovskite includes at least two spacer cations, and the iodine-based perovskite comprises a structure with the structural formula NMA. x PPA y Cs w Pb m I i The compound, of which 0.08

Description

Technical Field

[0001] This invention relates to luminescent materials, specifically to a red perovskite luminescent material, its preparation method, and a light-emitting diode device. Background Technology

[0002] Red light, as one of the three primary colors of light emission, is of great significance for full-color displays. In recent years, the development of perovskite light-emitting diode (PeLED) devices has been very rapid, especially green and near-infrared PeLED devices, whose performance is almost comparable to that of commercial light-emitting diode devices. However, the development of pure red PeLEDs is still relatively lagging behind, and the device efficiency and spectral stability need to be improved, which seriously limits their practical applications.

[0003] Currently, several methods have been developed to precisely tune the emission wavelength of perovskite perovskites for achieving pure red light emission. One widely adopted method is the mixed halide strategy. However, under the influence of an electric field, phase separation occurs in the mixed halide perovskite system due to ion migration, leading to changes in the electroluminescence (EL) spectrum of the device and a subsequent deterioration in device performance. Summary of the Invention

[0004] To overcome the existing technical problems, the present invention aims to provide a red-light perovskite luminescent material, a preparation method, and a light-emitting diode device. The red-light perovskite luminescent material is a quasi-two-dimensional luminescent material with high purity of emitted red light.

[0005] To achieve the above objectives, the present invention employs the following technical solution: a red-light perovskite luminescent material, comprising iodine-based perovskite, wherein the iodine-based perovskite comprises at least two-membered spacer cations, and the iodine-based perovskite comprises materials with the structural formula NMA. x PPA y Cs w Pb m I i The compound, of which 0.08 <x<0.16,0.08<y<0.16,0.06<w<0.2,0.06<m<0.2,0.3<i<1。

[0006] The iodine-based perovskite comprises a ternary spacer cation, and the iodine-based perovskite comprises a structure with the structural formula NMA. x PPA y TMA z Cs w Pb m I i The compound, of which 0.08 <x<0.16,0.08<y<0.16,0.01<z<0.05,0.06<w<0.2,0.06<m<0.2,0.3<i<1。

[0007] The emission wavelength of the red perovskite luminescent material is 630-640nm.

[0008] This invention includes a second technical solution, a method for preparing a red-light perovskite luminescent material, comprising:

[0009] Using cesium iodide and lead iodide as precursors, a first precursor solution is formed by the reaction.

[0010] 1-Naphthylmethylammonium iodide and phenylpropylammonium iodide are dissolved in the first precursor solution, heated and stirred at a first temperature, and then post-treated to obtain a first iodine-based perovskite. The red-light perovskite luminescent material includes the first iodine-based perovskite, which comprises materials with the structural formula NMA. x PPA y Cs w Pb m I i compounds,

[0011] Among them, 0.08 <x<0.16,0.08<y<0.16,0.06≤w≤0.2,0.06≤m≤0.2,0.3≤i≤1。

[0012] The step of dissolving 1-naphthylmethylammonium iodide and phenylpropylammonium iodide in the first precursor solution, heating and stirring at a first temperature, and then performing post-treatment to obtain the first iodine-based perovskite includes:

[0013] 1-Naphthylmethylammonium iodide and phenylpropylammonium iodide are dissolved in the first precursor solution and heated and stirred at a first temperature to form a second precursor solution;

[0014] 2-Thiophenemethylammonium iodide was added to a second precursor solution and reacted at a second temperature. Post-treatment yielded a second iodine-based perovskite. The red-light perovskite luminescent material included the second iodine-based perovskite, which contained a structure with the structural formula NMA. x PPA y TMA z Cs w Pb m I i The compound, of which 0.08 <x<0.16,0.08<y<0.16,0.01<z<0.05,0.06≤w≤0.2,0.06≤m≤0.2,0.3≤i≤1。

[0015] The first temperature is greater than or equal to 60℃, and the second temperature is greater than or equal to 60℃.

[0016] The molar ratio of 1-naphthylmethylammonium iodide to phenylpropylammonium iodide is 1:2-2:1.

[0017] The mass ratio of 2-thiophenemethylammonium iodide to 1-naphthylmethylammonium iodide is (3-7):22.8.

[0018] The present invention includes a third technical solution, a light-emitting diode device, comprising the above-mentioned red perovskite light-emitting material, or the red perovskite light-emitting material prepared by the above-mentioned preparation method.

[0019] The light-emitting diode device further includes a transparent anode, a hole injection layer, a hole transport layer, an interface modification layer, an electron transport layer, an electron injection layer, and a cathode. The red perovskite light-emitting material forms the light-emitting layer, which is located between the interface modification layer and the electron transport layer.

[0020] Compared with the prior art, the present invention has the following obvious and prominent substantive features and significant advantages:

[0021] 1. The red-light perovskite luminescent material of this invention uses pure halogen. The iodine-based perovskite in the red-light perovskite material contains a single halide ion, resulting in a stable perovskite lattice. Under the influence of an electric field, the perovskite material is less prone to ion migration, which promotes spectral stability.

[0022] 2. The red perovskite luminescent material of the present invention is prepared by using binary or ternary spacer cations and fabricated into a light-emitting diode device. The binary spacer cations NMAI and PPAI or the three spacer cations NMAI, PPAI, and TMAI can achieve higher external quantum efficiency and brightness.

[0023] 3. The preparation method of the red perovskite luminescent material of the present invention employs a predetermined sequence for preparing the precursor solution. First, CsI and PbI2 are added to form a three-dimensional CsPbI3 solution, followed by the sequential addition of NMAI, PPAI, and TMAI to form a regular quasi-two-dimensional perovskite precursor solution. This effectively achieves phase modulation within the perovskite. Simultaneously, the regular addition of spacer cations results in different octahedral coordination, thereby adjusting the peak position of pure red light and achieving spectral stability and repeatability. The present invention, through the regular preparation of a pure iodine-based precursor solution, effectively suppresses ion migration, promotes carrier transport, achieves stable pure red light emission peak positions, and improves the efficiency of light-emitting diode devices. Attached Figure Description

[0024] Figure 1 This is a schematic diagram of the absorption intensity and photoluminescence intensity-wavelength of the light-emitting layer in Embodiment 1 of the present invention.

[0025] Figure 2 This is a schematic diagram of the structure of the light-emitting diode device of the present invention.

[0026] Figure 3 This is a current density-external quantum efficiency diagram of the light-emitting diode device in Embodiment 1 of the present invention.

[0027] Figure 4 The images show the electroluminescence spectra of the light-emitting diode devices under different voltages in Embodiment 1 of the present invention.

[0028] Figure 5a The diagram shows the current density-external quantum efficiency of the light-emitting diode devices in Embodiments 2 and 3 of this invention.

[0029] Figure 5b The diagram shows the current density-voltage-brightness of the light-emitting diode devices in Embodiments 2 and 3 of the present invention.

[0030] Figure 6a The diagram shows the current density-external quantum efficiency of the light-emitting diode devices in Embodiments 4-6 of this invention.

[0031] Figure 6b The diagram shows the current density-voltage-brightness of the light-emitting diode devices in Embodiments 4-6 of this invention.

[0032] Figure 7 These are the normalized photoluminescence diagrams of Embodiments 1 and 2 of the present invention;

[0033] Figure 8 External quantum efficiency diagrams are generated for the light-emitting diode devices of Embodiments 1, 7, and 8 of this invention.

[0034] Figure 9 This is a current density-external quantum efficiency diagram for the LED device in Comparative Example 1.

[0035] Figure 10 The UV-Vis absorption spectra of Comparative Examples 2-5 are shown.

[0036] Figure 11 The images show the UV-Vis absorption spectra of Examples 1-2 and Comparative Examples 2-3.

[0037] Wherein: 1-substrate, 2-ITO anode, 3-hole transport layer, 4-hole injection layer, 5-interface modification layer, 6-perovskite luminescent layer, 7-electron transport layer, 8-electrode modification layer, 9-cathode. Detailed Implementation

[0038] The present invention will now be described in detail with reference to the accompanying drawings and embodiments. It should be noted that these embodiments are for illustrative purposes only and do not limit the scope of the invention. After reading this description, any modifications and substitutions made by those skilled in the art to the present invention fall within the scope defined by the appended claims. Preferred embodiments of the present invention are detailed below:

[0039] Under the influence of an electric field, phase separation occurs in the mixed halide perovskite system due to ion migration, which leads to changes in the electroluminescence (EL) spectrum of the device and a deterioration in device performance. When using pure halogen to prepare PeLEDs devices, there is spectral instability.

[0040] Therefore, this application provides a red-light perovskite luminescent material, which includes an iodine-based perovskite, wherein the iodine-based perovskite includes at least two spacer cations, and the iodine-based perovskite includes a structure with the structural formula NMA. x PPA y Cs w Pb m I i The compound, of which 0.08 <x<0.16,

[0041] 0.08 <y<0.16,0.06<w<0.2,0.06<m<0.2,0.3<i<1。

[0042] The iodine-based perovskite comprises a ternary spacer cation, and the iodine-based perovskite comprises a structure with the structural formula NMA. x PPA y TMA z Cs w Pb m I i The compound, of which 0.08 <x<0.16,0.08<y<0.16,0.01<z<0.05,0.06<w<0.2,0.06<m<0.2,0.3<i<1。

[0043] The emission wavelength of the red perovskite luminescent material is 630-640nm.

[0044] This invention includes a second technical solution, a method for preparing a red-light perovskite luminescent material, comprising:

[0045] S110: Using cesium iodide and lead iodide as precursors, a first precursor solution is formed by the reaction.

[0046] In this embodiment, cesium iodide (CsI) and lead iodide (PbI2) are dissolved in N,N-dimethylformamide (DMF), heated and stirred at a temperature not lower than 60°C for at least 4 hours, and then filtered using a polytetrafluoroethylene filter with a pore size not higher than 0.45 μm to obtain a first precursor solution, which is stored in a nitrogen atmosphere for later use.

[0047] S120: 1-Naphthylmethylammonium iodide and phenylpropylammonium iodide are dissolved in the first precursor solution, heated and stirred at a first temperature, and then post-treated to obtain a first iodine-based perovskite. The red-light perovskite luminescent material includes the first iodine-based perovskite, which comprises materials with the structural formula NMA. x PPA y Cs w Pb m I i The compound, of which 0.08 <x<0.16,0.08<y<0.16,0.06≤w≤0.2,0.06≤m≤0.2,0.3≤i≤1。

[0048] In this embodiment, 1-naphthylmethylammonium iodide (NMAI) and phenylpropylammonium iodide (PPAI) are dissolved in a first precursor solution, heated and stirred at a temperature of not less than 60°C for at least 4 hours, and then filtered using a polytetrafluoroethylene filter with a pore size of not more than 0.45 μm to obtain a second precursor solution, which is a red perovskite luminescent material solution.

[0049] In another embodiment, a method for preparing a red-light perovskite luminescent material includes:

[0050] S210: Using cesium iodide and lead iodide as precursors, a first precursor solution is formed by the reaction.

[0051] In this embodiment, cesium iodide (CsI) and lead iodide (PbI2) are dissolved in N,N-dimethylformamide (DMF), heated and stirred at a temperature not lower than 60°C for at least 4 hours, and then filtered using a polytetrafluoroethylene filter with a pore size not higher than 0.45 μm to obtain a first precursor solution, which is stored in a nitrogen atmosphere for later use.

[0052] S220: Dissolve 1-naphthylmethylammonium iodide and phenylpropylammonium iodide in the first precursor solution, and heat and stir at a first temperature to obtain a second precursor solution.

[0053] In this embodiment, 1-naphthylmethylammonium iodide (NMAI) and phenylpropylammonium iodide (PPAI) are dissolved in a first precursor solution, heated and stirred at a temperature of not less than 60°C for at least 4 hours, and then filtered using a polytetrafluoroethylene filter with a pore size of not more than 0.45 μm to obtain a second precursor solution.

[0054] S230: 2-Thiophenemethylammonium iodide is added to the second precursor solution and reacted at a second temperature. Post-treatment yields a second iodine-based perovskite. The red-light perovskite luminescent material includes the second iodine-based perovskite, which comprises a structure with the structural formula NMA. x PPA y TMA z Cs w Pb m I i The compound, of which 0.08 <x<0.16,0.08<y<0.16,0.01<z<0.05,0.06≤w≤0.2,0.06≤m≤0.2,0.3≤i≤1。

[0055] In this embodiment, 2-thiophene methyl ammonium iodide (TMAI) is dissolved in a second precursor solution, heated and stirred at a temperature not lower than 60°C for 4 hours, and then filtered using a polytetrafluoroethylene filter with a pore size not higher than 0.45 μm to obtain a red perovskite luminescent material solution.

[0056] The molar ratio of 1-naphthylmethylammonium iodide to phenylpropylammonium iodide is 1:2-2:1.

[0057] The mass ratio of 2-thiophenemethylammonium iodide to 1-naphthylmethylammonium iodide is (3-7):22.8.

[0058] The present invention includes a third technical solution, a light-emitting diode device, comprising the above-mentioned red perovskite light-emitting material, or the red perovskite light-emitting material prepared by the above-mentioned preparation method.

[0059] The light-emitting diode device further includes a transparent anode, a hole injection layer, a hole transport layer, an interface modification layer, an electron transport layer, an electron injection layer, and a cathode. The red perovskite light-emitting material forms the light-emitting layer, which is located between the interface modification layer and the electron transport layer.

[0060] Preferably, the hole injection layer comprises a poly(3,4-ethylenedioxythiophene):poly(4-styrenesulfonic acid) (PEDOT:PSS) film, and the thickness of the hole injection layer is 35-40 nm.

[0061] Preferably, the hole transport layer comprises a poly[bis(4-phenyl)2,4,6-trimethylphenyl]amine (PTAA) film with a thickness of 35–40 nm.

[0062] Preferably, the interface modification layer comprises a [2-(9H-carbazole-9-yl)ethyl]phosphonic acid (2PACz) film with a thickness of 3-5 nm.

[0063] Preferably, the thickness of the perovskite luminescent layer is 35–40 nm.

[0064] Preferably, the external quantum efficiency of the perovskite emitting layer is 20%, and the emission wavelength is 630-640 nm.

[0065] Preferably, the electron transport layer comprises 1,3,5-tris(1-phenyl-1H-benzimidazol-2-yl)benzene (TPBi), tris(2,4,6-trimethyl-3-(pyridin-3-yl)phenyl)borane (3TPYMB), or 4,6-bis(3,5-di(pyridin-3-yl)phenyl)-2-methylpyrimidine (4,6-Bis(3,5-di... One or more of (pyridin-3-yl)phenyl)-2-methylpyrimidine (B3PYMPM) or (1,3,5-triazine-2,4,6-triyl)tri(phenyl-3,1-diyl))tri(diphenylphosphinyl)(2,4,6-Tris[3-(diphenylphosphinyl)phenyl]-1,3,5-triazine (PO-T2T) have a thickness of 30-35 nm.

[0066] Preferably, the electrode modification layer comprises a lithium fluoride (LiF) film with a thickness of 1 nm.

[0067] Preferably, the cathode comprises an Al electrode with a thickness of not less than 100 nm.

[0068] The present invention includes a fourth technical solution, a light-emitting device, comprising the above-mentioned red perovskite light-emitting material, or the red perovskite light-emitting material prepared by the above-mentioned preparation method, or the above-mentioned light-emitting diode device.

[0069] For ease of understanding, the following specific embodiments are provided.

[0070] Example 1: The following specific content is provided in this example.

[0071] a. The preparation of red-light perovskite luminescent materials is as follows:

[0072] (1) First precursor solution: CsI (23.8 mg) and PbI2 (55.3 mg) were dissolved in 1 mL of DMF, heated and stirred at 60 °C for 4 h, and then filtered using a polytetrafluoroethylene filter with a pore size not higher than 0.45 μm to obtain the first precursor solution.

[0073] (2) Second precursor solution: NMAI (22.8 mg) and PPAI (10.5 mg) were dissolved in the first precursor solution, heated and stirred at 60 °C for 4 h, and then filtered with a polytetrafluoroethylene filter with a pore size of no more than 0.45 μm to obtain the second precursor solution, wherein the molar ratio of NMAI to PPAI is 0.08:0.04.

[0074] (3) Red perovskite luminescent material solution: Dissolve TMAI (7mg) in the second precursor solution, heat and stir at 60℃ for 4h, then filter using a polytetrafluoroethylene filter with a pore size not higher than 0.45μm to obtain the red perovskite luminescent material solution, and store it in a nitrogen environment for use.

[0075] b. Fabrication of light-emitting diode devices (positive structure).

[0076] like Figure 2 As shown, from bottom to top, a substrate 1 is first used, on which an ITO anode 2 is provided; on the top of the ITO anode 2, a hole injection layer 3, a hole transport layer 4, an interface modification layer 5, a light-emitting layer 6, an electron transport layer 7, an electron modification layer 8, and a cathode 9 are sequentially provided. The hole injection layer 3, hole transport layer 4, interface modification layer 5, light-emitting layer 6, electron transport layer 7, and electron modification layer 8 form a light-emitting unit, thus obtaining a light-emitting diode device.

[0077] The steps for fabricating a light-emitting diode (LED) device are as follows:

[0078] (1) Cleaning of glass substrate containing ITO transparent electrode (i.e. anode): First, wipe the ITO glass substrate with a lint-free cloth soaked in detergent, then clean it with deionized water, acetone and isopropanol in sequence for 15 minutes each, then dry the glass substrate and treat its surface with oxygen plasma gas for 15 minutes.

[0079] (2) Preparation of hole injection layer: PEDOT:PSS was spin-coated on ITO glass at a speed of 4000 r.pm for 40 s. After spin-coating, it was annealed at 150℃ for 15 min to a thickness of 35 nm.

[0080] (3) Preparation of hole transport layer: A PTAA solution dissolved in chlorobenzene (CB) with a concentration of 8 mg / ml was spin-coated onto a PEDOT:PSS film at a speed of 4000 r·pm for 40 s. After spin-coating, the film was annealed at 120℃ for 20 min. The thickness of the hole transport layer was 40 nm.

[0081] (4) Preparation of the interfacial modification layer: Spin-coat a solution of 2PACz dissolved in ethanol on the PTAA film at a concentration of 0.02 mg / ml, a rotation speed of 4000 r.p.m., and a spin-coating time of 40 s. After spin-coating, anneal at 100 °C for 5 min. The thickness of the interfacial modification layer is 3 nm.

[0082] (5) Preparation of the light-emitting layer: After oxygen plasma gas treatment, spin-coat a solution of a red-light perovskite light-emitting material. The red-light perovskite light-emitting material solution is a quasi-two-dimensional pure halogen perovskite NMA x PPA y TMA z Cs 0.09 Pb 0.12 I 0.56 (0.08 < x < 0.16, 0.08 < y < 0.16, 0.01 < z < 0.05) structure, dissolved in N,N-dimethylformamide (DMF) at a concentration of 0.12 mol / L, a rotation speed of 4500 r.p.m., and a spin-coating time of 40 min. After spin-coating, anneal at 80 °C for 5 min. The thickness of the light-emitting layer is 35 nm.

[0083] (6) Preparation of the electron transport layer: Transfer the spin-coated device to a vacuum evaporation chamber. After pumping the vacuum to 10 -4 Pa, evaporate TPBi at a speed with a thickness of 30 nm.

[0084] (7) Preparation of the electron injection layer / electrode modification layer: After evaporating the electron transport layer TPBi, then evaporate LiF at a speed with a thickness of 1 nm.

[0085] (8) Cathode: Finally, evaporate the Al electrode at a speed with a thickness of 100 nm.

[0086] Example 2

[0087] The difference between this example and Example 1 is that NMAI:PPAI is different from that in Example 1, and the others are similar to Example 1. Specifically, it includes:

[0088] a. The preparation of the red-light perovskite light-emitting material is as follows:

[0089] (1) The first precursor solution: Dissolve CsI (23.8 mg) and PbI2 (55.3 mg) in 1 mL of DMF, heat and stir at 60 °C for 4 h, and then filter using a polytetrafluoroethylene filter with a pore size not higher than 0.45 μm to obtain the first precursor solution.

[0090] (2) Second precursor solution: The total molar mass of NMAI and PPAI is 0.12 mmol, NMAI:PPAI = 0.08:0.04, which is dissolved in the first precursor solution, heated and stirred at 60 °C for 4 h, and then filtered using a polytetrafluoroethylene filter with a pore size not higher than 0.45 μm to obtain the second precursor solution. This second precursor solution is a red-light perovskite luminescent material solution, which is stored in a nitrogen environment for use. The red-light perovskite luminescent material includes NMA x PPA y Cs 0.09 Pb 0.12 I 0.56 (0.08 < x < 0.16, 0.08 < y < 0.16).

[0091] b. The preparation of the light-emitting diode device is similar to that of Example 1 and will not be elaborated here.

[0092] Example 3

[0093] The difference from Example 2 is that NMAI:PPAI = 0.04:0.08, and others are similar to Example 2 and will not be elaborated here.

[0094] Examples 4 - Examples 6

[0095] The difference from Example 1 is that in the preparation of the red-light perovskite luminescent material solution, the mass concentrations of TMAI are 1 mg / mL, 3 mg / mL, and 5 mg / mL respectively, and the overall solution is 1 mL. Others are similar to Example 1 and will not be elaborated here. Among them, the red-light perovskite luminescent material includes a compound with the structural formula NMA x PPAA y TMA z Cs w Pb m I i (0.08 < x < 0.16, 0.08 < y < 0.16, 0.01 < z < 0.05, 0.06 < w < 0.2, 0.06 < m < 0.2, 0.3 < i < 1).

[0096] Example 7

[0097] The difference from Example 1 is that in the preparation of the red-light perovskite luminescent material, (1) the solvent of the first precursor solution is DMSO. Others are the same as Example 1 and will not be elaborated here.

[0098] Example 8

[0099] The difference from Example 1 is that in the preparation of the red-light perovskite luminescent material, (1) the solvent of the first precursor solution is DMI. Others are the same as Example 1 and will not be elaborated here.

[0100] Comparative Example 1

[0101] In this embodiment, the organic spacer cations NMAI, PPAI, and TMAI are replaced, specifically as follows:

[0102] a. Fabrication of pure iodine red perovskite light-emitting diodes using three spacer cations: PEAI, BAI, and NMAI.

[0103] (1) First precursor solution: CsI (23.8 mg) and PbI2 (55.3 mg) were dissolved in 1 mL of DMF, heated and stirred at 60 °C for 4 h, and then filtered using a polytetrafluoroethylene filter with a pore size of no more than 0.45 μm to obtain the first precursor solution;

[0104] (2) Second precursor solution: PEAI (9.96 mg) and BAI (14.7 mg) were dissolved in the first precursor solution, heated and stirred at 60°C for 4 h, and then filtered using a polytetrafluoroethylene filter with a pore size of no more than 0.45 μm to obtain the second precursor solution;

[0105] (3) Red perovskite luminescent material solution: Dissolve NMAI (1 mg) in the second precursor solution, heat and stir at 60°C for 4 h, and then filter using a polytetrafluoroethylene filter with a pore size not higher than 0.45 μm to obtain the red perovskite luminescent material solution, which is stored in a nitrogen environment for use.

[0106] b. Fabrication of pure red iodine-based perovskite light-emitting devices (upright structure)

[0107] The process, from bottom to top, begins with a substrate 1, on which an ITO anode 2 is mounted. On top of the ITO anode 2, a hole injection layer 3, a hole transport layer 4, an interface modification layer 5, a perovskite light-emitting layer 6, an electron transport layer 7, an electron modification layer 8, and a cathode 9 are sequentially arranged. The hole injection layer 3, hole transport layer 4, interface modification layer 5, perovskite light-emitting layer 6, electron transport layer 7, and electron modification layer 8 form the light-emitting unit, resulting in a quasi-two-dimensional pure red iodine-based perovskite light-emitting diode device. (See [reference needed]). Figure 2 The steps for fabricating a quasi-two-dimensional pure red iodine-based perovskite light-emitting device are as follows:

[0108] (1) Cleaning of glass substrate containing ITO transparent electrode (i.e. anode): First, wipe the ITO glass substrate with a lint-free cloth soaked in detergent, then clean it with deionized water, acetone and isopropanol in sequence for 15 minutes each, then dry the glass substrate and treat its surface with oxygen plasma gas for 15 minutes.

[0109] (2) Preparation of hole injection layer: PEDOT:PSS was spin-coated on ITO glass at a rotation speed of 4000 r.p.m. for 40 s, and annealed at 150 °C for 15 min after spin-coating.

[0110] (3) Preparation of hole transport layer: A solution of PTAA dissolved in chlorobenzene (CB) with a concentration of 8 mg / ml was spin-coated on the PEDOT:PSS film at a rotation speed of 4000 r.p.m. for 40 s, and annealed at 120 °C for 20 min after spin-coating.

[0111] (4) Preparation of interface modification layer: A solution of 2PACz dissolved in ethanol with a concentration of 0.02 mg / ml was spin-coated on the PTAA film at a rotation speed of 4000 r.p.m. for 40 s, and annealed at 100 °C for 5 min after spin-coating.

[0112] (5) Preparation of perovskite light-emitting layer: After oxygen plasma gas treatment, a red-light perovskite solution was spin-coated. The red-light perovskite was a quasi-two-dimensional halogen perovskite PEA x BA y NMA z Cs 0.09 Pb 0.12 I 0.56 (0.08 < x < 0.16, 0.08 < y < 0.16, 0.01 < z < 0.05) structure, dissolved in N,N-dimethylformamide (DMF) with a concentration of 0.12 mol / L, at a rotation speed of 4500 r.p.m. for 40 min, and annealed at 80 °C for 5 min after spin-coating.

[0113] (6) Preparation of electron transport layer: The spin-coated device was transferred to a vacuum evaporation chamber. After the vacuum was pumped to 10 -4 Pa, TPBi was evaporated at a speed with a thickness of 30 - 35 nm.

[0114] (7) Preparation of electron injection layer / electrode modification layer: After evaporating the electron transport layer TPBi, LiF was then evaporated at a speed with a thickness of 1 nm.

[0115] (8) Cathode: Finally, an Al electrode was evaporated at a speed with a thickness of 100 nm.

[0116] Comparative Example 2

[0117] The difference from Example 1 is that steps (2) and (3) are not included in the preparation of the red perovskite luminescent material, as follows: (1) First precursor solution: CsI (23.8 mg) and PbI2 (55.3 mg) are dissolved in 1 mL of DMF, heated and stirred at 60 °C for 4 h, and then filtered using a polytetrafluoroethylene filter with a pore size not higher than 0.45 μm to obtain the precursor solution. The red perovskite luminescent material is CsI. 0.09 Pb 0.12 I 0.3 The fabrication of the light-emitting diode device is similar to that in Example 1, and will not be described again here.

[0118] Comparative Example 3

[0119] The difference from Example 1 lies in the specific preparation of the red-light perovskite luminescent material, which is as follows. Other aspects are similar to Example 1 and will not be repeated here. The preparation of the red-light perovskite luminescent material includes: dissolving CsI (23.8 mg), PbI2 (55.3 mg), and NMAI (28.6 mg) in 1 mL of DMF, heating and stirring at 60°C for 4 h, and then filtering using a polytetrafluoroethylene filter with a pore size not exceeding 0.45 μm to obtain the second precursor solution.

[0120] Comparative Example 4

[0121] The difference from Example 1 lies in the specific preparation of the red-light perovskite luminescent material, which is as follows. Other aspects are similar to Example 1 and will not be repeated here. The preparation of the red-light perovskite luminescent material includes: dissolving CsI (23.8 mg), PbI2 (55.3 mg), and PPAI (10.5 mg) in 1 mL of DMF, heating and stirring at 60°C for 4 h, and then filtering using a polytetrafluoroethylene filter with a pore size not exceeding 0.45 μm to obtain the red-light perovskite luminescent material solution.

[0122] Comparative Example 5

[0123] The difference from Example 1 lies in the specific preparation of the red-light perovskite luminescent material, which is as follows. Other aspects are similar to Example 1 and will not be repeated here. The preparation of the red-light perovskite luminescent material includes: dissolving CsI (23.8 mg), PbI2 (55.3 mg), and TMAI (7 mg) in 1 mL of DMF, heating and stirring at 60°C for 4 h, and then filtering using a polytetrafluoroethylene filter with a pore size no higher than 0.45 μm to obtain a red-light perovskite luminescent material solution.

[0124] Test methods for ultraviolet-visible absorption spectroscopy:

[0125] The absorption of the red-light perovskite luminescent material solutions of Examples 1, 2, and Comparative Examples 1-5 was measured using a UV-Vis absorption spectrometer.

[0126] (1) Clean the white glass substrate: First, wipe the white glass substrate with a lint-free cloth soaked in detergent. Then, use deionized water, acetone and isopropanol for continuous ultrasonic cleaning for 15 minutes each. After that, dry the glass substrate and treat its surface with oxygen plasma gas for 5 minutes.

[0127] (2) Preparation of the light-emitting layer: After treatment with oxygen plasma gas, the red light perovskite light-emitting material solution was spin-coated at a speed of 4500 r.pm and a spin-coating time of 40s. After spin-coating, the material was annealed at 80℃ for 5min.

[0128] (3) The ultraviolet-visible absorption spectrum of the perovskite thin film was measured using a 365nm excitation light source.

[0129] The test results of each embodiment and comparative example are as follows: Figures 1-11 As shown.

[0130] The absorption and photoluminescence intensity of the quasi-two-dimensional pure red iodine-based perovskite film used as the emitting layer in Example 1 were measured, and the absorption intensity and photoluminescence intensity-wavelength diagrams were obtained, as shown below. Figure 1 As shown, its absorption phase distribution conforms to the phase distribution of a quasi-two-dimensional perovskite, and the photoluminescence peak is between 630-640 nm, which is consistent with the pure red light emission range.

[0131] The light-emitting diode device of Example 1 was characterized by electroluminescence spectroscopy, and the electroluminescence spectrum was obtained, as shown below. Figure 4 As shown, its emission peak is located at 638 nm, which is in the pure red light range. Furthermore, under the continuous action of the bias voltage (3-6V), the spectrum did not shift, indicating that the ternary spacer cations play a role in stabilizing the spectrum in the quasi-two-dimensional pure red iodine-based PeLEDs.

[0132] The performance of the light-emitting diode device in Example 1 was tested, and the external quantum efficiency and peak position at different voltages were obtained. Figure 3 and 4 As shown, this method achieves an external quantum efficiency of 20%, demonstrating that the LED device fabricated using this method exhibits high external quantum efficiency and good device performance.

[0133] like Figure 5a As shown, the external quantum efficiency diagrams of the light-emitting diode devices in Examples 2 and 3 are presented. The external quantum efficiency diagrams of the light-emitting diode devices in Examples 4-6 are shown below. Figure 6a As shown, when the NMAI:PPAI concentration is 0.08:0.04, the external quantum efficiency (EQE) reaches 13.2%, which is better than the EQE (11%) at the 0.04:0.08 concentration. Figure 6aAs shown, after the introduction of TMAI, the EQE gradually increased with the recent increase in concentration (3mg-7mg), reaching 19.18%. Figure 5b As shown, when the NMAI:PPAI concentration is 0.08:0.04, the luminance can reach as high as 1000 cd·m. -2 .like Figure 6b As shown, after introducing TMAI, the brightness of the light-emitting diode device can reach up to 950 cd·m. -2 .

[0134] Electroluminescence peak positions of Examples 1 and 2 are shown below. Figure 7 As shown, after the introduction of TMAI, the emission peak position is closer to the emission peak position of pure red light (620-640nm), which conforms to the Rec.2020 standard launched by the International Telecommunication Union.

[0135] The external quantum efficiency of the light-emitting diode devices of Examples 1, 7, and 8 was tested, such as... Figure 8 As shown, this indicates that the quasi-two-dimensional pure red iodine-based perovskite powder is suitable for use in the above-mentioned different organic solvents.

[0136] like Figure 9 As shown, the external quantum efficiency of the LED device in Comparative Example 1 reached a maximum of 10%. The external quantum efficiency of the LED devices fabricated from three-spacing pure iodine red perovskites prepared by PEAI, BAI, and NMAI was half that of the LED devices fabricated from three-spacing pure iodine red perovskites prepared by NMI, PPAI, and TMAI.

[0137] The ultraviolet absorption spectra of the red perovskite luminescent material solutions from Examples 1 and 2, as well as Comparative Examples 2-5, were measured. Figure 10 , 11As shown, perovskite films prepared solely with CsI and PbI2 exhibit a distinct n=1 phase in the absorption range of 425nm-430nm, where n represents the number of perovskite layers. When NMAI and PPAI are introduced, the peak of the n=1 phase decreases significantly, and an n=2 phase forms in the 500nm-520nm range, while an n≥3 phase forms in the 600nm-650nm range. When TMAI is used alone, the n=1 phase decreases slightly, while the n=2 phase increases slightly. This indicates that NMAI, PPAI, and TMAI all have the ability to regulate phase distribution. Furthermore, we know that perovskite films with more small n-phases (n=1, n=2) have more defects, which affects the luminescence performance of the perovskite film. Therefore, the formation of large n-phases (n≥3) is beneficial to improving the optical properties of perovskite films. When NMAI, PPAI, and TMAI are added to the perovskite precursor solution in sequence, the resulting perovskite film shows a significant increase in the large n phase as the small n phase decreases. This indicates that the three-spaced organic cations are beneficial for preparing pure red perovskite light-emitting diode devices.

[0138] Based on Comparative Example 2, when only CsI and PbI2 are present in the precursor solution, an infinitely extended three-dimensional perovskite structure is formed. In Example 1 of this application, when organic cations NMAI, PPAI, and TMAI are introduced, the three-dimensional perovskite structure is separated, preventing it from extending infinitely and thus forming a quasi-two-dimensional perovskite structure. Therefore, these cations are called organic spacer cations. By first forming an octahedral structure like CsPbI3 in the precursor solution, when the spacer cations NMAI and PPAI enter the precursor solution, they can preferentially coordinate with the octahedron to form a quasi-two-dimensional structure, suppressing PbI2. 2+ and I - The migration of ions reduces defects caused by ion migration and also regulates the peak position of red iodine-based perovskite. When the spacer cation TMAI is added to the second precursor solution, it can act on the octahedrons that are not bound to the spacer cation, further regulating the phase distribution of red iodine-based perovskite and achieving the emission peak position of pure red light.

[0139] The embodiments of the present invention have been described above with reference to the accompanying drawings. However, the present invention is not limited to the above embodiments. Various changes can be made according to the purpose of the invention. Any changes, modifications, substitutions, combinations or simplifications made based on the spirit and principle of the technical solution of the present invention shall be equivalent substitutions. As long as they meet the purpose of the invention and do not deviate from the concept of the invention, they shall fall within the protection scope of the present invention.

Claims

1. A method for preparing a red-light perovskite luminescent material, characterized in that, include: Using cesium iodide and lead iodide as precursors, a first precursor solution is formed by the reaction. 1-Naphthylmethylammonium iodide and phenylpropylammonium iodide are dissolved in the first precursor solution and heated and stirred at a first temperature to form a second precursor solution; Add 2-thiophenemethylammonium iodide to the second precursor solution, react at the second temperature, and perform post-treatment to obtain a second iodine-based perovskite. The red-light perovskite luminescent material includes the second iodine-based perovskite, and the second iodine-based perovskite includes a compound with the structural formula NMA x PPA y TMA z Cs w Pb m I i where 0.08 < x < 0.16, 0.08 < y < 0.16, 0.01 < z < 0.05, 0.06 ≤ w ≤ 0.2, 0.06 ≤ m ≤ 0.2, 0.3 ≤ i ≤ 1; the emission wavelength of the red-light perovskite luminescent material is 630 - 640 nm; the molar ratio of 1-naphthalenemethylammonium iodide to phenylpropylammonium iodide is 1:2 - 2:

1.

2. The method for preparing the red-light perovskite luminescent material according to claim 1, characterized in that, The mass ratio of 2-thiophenemethylammonium iodide to 1-naphthylmethylammonium iodide is (3-7):22.

8.

3. The method for preparing the red-light perovskite luminescent material according to claim 1, characterized in that, The first temperature is greater than or equal to 60℃, and the second temperature is greater than or equal to 60℃.

4. A red perovskite luminescent material prepared by the method according to any one of claims 1-3, characterized in that, Red-light perovskite luminescent materials include iodine-based perovskite, wherein the iodine-based perovskite comprises ternary spacer cations, and the iodine-based perovskite comprises materials with the structural formula NMA. x PPA y TMA z Cs w Pb m I i The compound, of which 0.08 <x<0.16,0.08<y<0.16,0.01<z<0.05,0.06<w<0.2,0.06<m<0.2,0.3<i<1。 5. A light-emitting diode device, characterized in that, Includes the red perovskite luminescent material as described in claim 4, or the red perovskite luminescent material prepared by the preparation method of any one of claims 1-3.

6. The light-emitting diode device according to claim 5, characterized in that, It also includes a transparent anode, a hole injection layer, a hole transport layer, an interface modification layer, an electron transport layer, an electron injection layer, and a cathode. The red perovskite luminescent material forms the luminescent layer, which is located between the interface modification layer and the electron transport layer.

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