阅读说明：本技术 一种大面积钙钛矿发光薄膜及其发光二极管 (Large-area perovskite light-emitting film and light-emitting diode thereof ) 是由 郭飞 陈超然 麦耀华 于 2021-07-19 设计创作，主要内容包括：本发明公开了一种大面积钙钛矿发光薄膜及其发光二极管,所述的大面积钙钛矿发光薄膜高度致密、光致发光效率高,该大面积钙钛矿发光薄膜的印刷制备方法,通过真空预处理能够将湿膜的溶剂挥发和钙钛矿薄膜热退火结晶两个关键步骤分开,从而实现钙钛矿发光薄膜制备过程中结晶动力学的控制,解决了传统旋涂工艺无法制备均匀的大面积钙钛矿发光层的问题。在大面积钙钛矿发光薄膜的印刷制备工艺基础上,同时制备出发光均匀、外量子效率高的大面积钙钛矿发光二极管,该制备发光二极管的工艺步骤简单,解决了目前制备工艺(如旋涂法、反溶剂萃取法)对钙钛矿发光二极管制备尺寸上的限制,得到了大面积发光强度均匀的钙钛矿发光二极管。(The invention discloses a large-area perovskite luminescent film and a light-emitting diode thereof, wherein the large-area perovskite luminescent film is highly compact and has high photoluminescence efficiency, and the printing preparation method of the large-area perovskite luminescent film can separate two key steps of solvent volatilization of a wet film and thermal annealing crystallization of the perovskite film through vacuum pretreatment, thereby realizing the control of crystallization kinetics in the preparation process of the perovskite luminescent film and solving the problem that the traditional spin coating process can not prepare uniform large-area perovskite luminescent layers. On the basis of the printing preparation process of the large-area perovskite light-emitting film, the large-area perovskite light-emitting diode with uniform light emission and high external quantum efficiency is prepared at the same time, the process for preparing the light-emitting diode is simple in step, the limitation of the current preparation process (such as a spin coating method and an anti-solvent extraction method) on the preparation size of the perovskite light-emitting diode is solved, and the large-area perovskite light-emitting diode with uniform light emission intensity is obtained.)

1. The printing preparation method of the large-area perovskite luminescent thin film is characterized by comprising the following preparation steps:

(1) depositing the perovskite precursor solution on a substrate by using a coating printing process to obtain a uniform precursor liquid film;

(2) vacuumizing the perovskite precursor liquid film obtained in the step (1) to obtain a pre-crystallized perovskite film;

(3) and (3) heating and annealing the pre-crystallized perovskite thin film obtained in the step (2) to obtain a perovskite luminescent thin film with sufficient crystallization.

The perovskite precursor in the perovskite precursor solution of the perovskite material in the step (1) is A_mB_n-1M_nX_3n+1Perovskite type, A is univalent or bivalent jumbo size amine radical cation; b is CH₃NH₃ ⁺、HC(NH₂)₂ ⁺Or Cs⁺At least one of; m is Pb²⁺Or Sn²⁺(ii) a X is Cl^-、Br^-Or I^-At least one of; wherein m is 1 or 2, and n is more than or equal to 1 and less than or equal to 5.

2. The large area perovskite luminescent film as claimed in claim 1, wherein the coating printing process in step (1) is at least one of knife coating, spray coating, slit extrusion printing or inkjet printing.

3. The large area perovskite luminescent thin film as claimed in claim 1, wherein the deposition of the perovskite precursor liquid film in step (1) is performed under a drying condition of 15-35 ℃.

4. The large area perovskite luminescent thin film as claimed in claim 1, wherein the perovskite precursor solution is prepared in step (1) by the following steps: mixing MX and AX₂(ii) a According to the following steps of 1: dissolving in organic solvent at a molar ratio of 1 to prepare AMX₃Mixing the solution to AMX₃Adding BX into the mixed solution to prepare A with different n values_mB_n-1M_nX_3n+1The perovskite precursor solution has m of 1 or 2 and n of 1-5.

5. The large-area perovskite luminescent thin film as claimed in claim 1, wherein the vacuum pre-crystallization treatment in step (2) is to reduce the vacuum degree to 10-8000 Pa at a speed of 40-230 Pa/s, and then maintain for 0.1-5 min for pre-crystallization, which is also influenced by the ambient temperature and the solvent evaporation time.

6. The large-area perovskite luminescent thin film as claimed in claim 5, wherein the vacuum pre-crystallization treatment in the step (2) is to reduce the vacuum degree to 1000-1200 Pa at a speed of 100-120 Pa/s and then maintain the vacuum degree for 20-30 s for pre-crystallization.

7. The large area perovskite luminescent thin film as claimed in claim 1, wherein the annealing treatment in the step (3) is maintained at 50-180 ℃ for 0.1-20 min.

8. The light-emitting diode containing the large-area perovskite light-emitting thin film is characterized by sequentially comprising a transparent conductive substrate, a hole transport layer, a perovskite light-emitting layer, an electron transport layer and a metal electrode from bottom to top, wherein the perovskite light-emitting layer is the large-area perovskite light-emitting thin film layer.

9. The light emitting diode comprising the large area perovskite luminescent thin film as claimed in claim 8Characterized in that the hole transport layer material is NiO_xAt least one of PEDOT, PSS or PTAA.

10. The light-emitting diode comprising a large area perovskite luminescent thin film as claimed in claim 8, wherein the electron transport layer comprises TPBi and LiF electron transport layers.

Technical Field

The invention belongs to the field of preparation of novel electronic components, and particularly relates to a large-area perovskite light-emitting thin film and a light-emitting diode thereof.

Background

In recent years, metal halide perovskites, as direct bandgap semiconductor materials, exhibit excellent carrier transport characteristics and higher photoluminescence efficiency. Electroluminescent diode devices based on perovskite thin films have a range of excellent properties, including: high color purity, wide color gamut range and high external quantum conversion efficiency. In addition, the characteristic of low-temperature solution processing enables the preparation cost to be lower. Therefore, the perovskite light emitting diode has wide application prospect in the fields of large-area illumination and flat panel display.

However, current perovskite luminescent thin films are mainly prepared using a spin-coating process in combination with anti-solvent crystallization. Due to the defects of the spin coating process, when the area of the perovskite luminescent film layer is increased, the defects of the spin coating process are particularly prominent: in the centrifugal deposition process, a large amount of solution is thrown out of the substrate to cause material waste, and meanwhile, a large-area uniform perovskite luminescent film cannot be obtained due to the action of centrifugal force. Therefore, the spin coating process widely used at present cannot meet the preparation of the large-area perovskite luminescent thin film, and the application of the perovskite luminescent diode in the fields of large-area display and illumination is seriously hindered. In view of this, it is necessary to develop a reliable printing method for preparing large-area perovskite light emitting diodes.

Disclosure of Invention

In order to overcome the defects and shortcomings of the prior art, the invention aims to provide a large-area perovskite luminescent film, and solves the problems of incompact perovskite luminescent film prepared by the spin coating process, uneven thickness, low luminescent efficiency and high solution waste rate.

A second object of the present invention is to provide a light emitting diode comprising a large area perovskite light emitting thin film.

The primary purpose of the invention is realized by the following technical scheme:

a printing preparation method of a large-area perovskite luminescent thin film comprises the following preparation steps:

(1) depositing the perovskite precursor solution on a substrate by using a coating printing process to obtain a uniform precursor liquid film;

(2) vacuumizing the perovskite precursor liquid film obtained in the step (1) to obtain a pre-crystallized perovskite film;

(3) and (3) heating and annealing the pre-crystallized perovskite thin film obtained in the step (2) to obtain a perovskite luminescent thin film with sufficient crystallization.

The perovskite precursor in the perovskite precursor solution of the perovskite material in the step (1) is (A)_m(B)_n-1M_nX_3n+1Perovskite type, A is univalent or bivalent jumbo size amine radical cation; b is methylamine Cation (CH)₃NH₃ ⁺) Formamidine cation (HC (NH)₂)₂ ⁺) Or cesium ions (Cs)⁺) At least one of; m is Pb²⁺Or Sn²⁺(ii) a X is Cl^-、Br^-Or I^-At least one of; wherein m is 1 or 2, and n is more than or equal to 1 and less than or equal to 5.

Preferably, the coating printing process in step (1) is at least one of knife coating, spray coating, slot extrusion printing or inkjet printing.

Preferably, the coating printing process in step (1) is a knife coating method or a slit extrusion printing method.

Preferably, said a is an ethylamine ion (EA)⁺) Propylamine ion (PA)⁺) Butylamine ion (BA)⁺) Isopropylamine Ion (iPA)⁺) Cyclopropylamine ion (CyPA)⁺) Phenylethylamine ion (PEA)⁺) Naphthylmethylamine ion (NMA)⁺) Dimethylamine ion (DMA)²⁺) Ethylenediamine (EDAD)²⁺) Butanediamine ion (BDAD)²⁺) And cyclohexanediamine ion (CyHDAD)²⁺)。。

Preferably, the deposition of the perovskite precursor liquid film in the step (1) is carried out under a drying condition of 15-35 ℃.

Preferably, the perovskite precursor solution is prepared in step (1) by the following specific steps: mixing MX and AX₂(ii) a According to the following steps of 1: dissolving in organic solvent at a molar ratio of 1 to prepare AMX₃Mixing the solution to AMX₃Adding BX into the mixed solution to prepare (A) with different n values_m(B)_n-1M_nX_3n+1A perovskite precursor solution of the type wherein m is 1Or 2, 1 is more than or equal to n is less than or equal to 5.

Preferably, the organic solvent of the perovskite precursor solution of step (1) is at least one of dimethyl sulfoxide (DMSO), N-dimethyl amide (DMF), gamma-butyrolactone (GBL) or N-methyl pyrrolidone (NMP).

Preferably, the organic solvent of step (1) is dimethyl sulfoxide (DMSO) or N-methylpyrrolidone (NMP) solvent.

Preferably, the concentration of the perovskite precursor in the perovskite precursor solution is 0.05-1.5M.

Preferably, the concentration of the perovskite precursor in the perovskite precursor solution is 0.5M.

Preferably, the vacuum pre-crystallization treatment in the step (2) is to reduce the vacuum degree to 10-8000 Pa at the speed of 40-230 Pa/s, and then maintain for 0.1-5 min for pre-crystallization, and the time is also influenced by the ambient temperature and the solvent evaporation time.

Preferably, the vacuum pre-crystallization treatment in the step (2) is to reduce the vacuum degree to 1000-1200 Pa at a speed of 100-120 Pa/s, and then maintain for 20-30 s for pre-crystallization.

Preferably, the vacuum pre-crystallization treatment in the step (2) is to reduce the vacuum degree to 1000Pa at the speed of 100Pa/s at 19 ℃, and then maintain 20s for pre-crystallization.

Preferably, the annealing treatment in the step (3) is maintained at 50-180 ℃ for 0.1-20 min.

Preferably, the annealing treatment in step (3) is maintained at 70 ℃ for 20 s.

The second purpose of the invention is realized by the following technical scheme:

the light-emitting diode with the large-area perovskite light-emitting thin film sequentially comprises a transparent conductive substrate, a hole transport layer, a perovskite light-emitting layer, an electron transport layer and a metal electrode from bottom to top, wherein the perovskite light-emitting layer is the large-area perovskite light-emitting thin film layer.

Preferably, the transparent conductive substrate material is ITO.

Preferably, the hole transport layer material is nickel oxide (NiO)_x) PEDOT PSS, poly[ bis (4-phenyl) (2,4, 6-trimethylphenyl) amine](PTAA).

Preferably, the electron transport layer comprises TPBi and LiF electron transport layers.

Compared with the prior art, the method has the following advantages:

(1) the printing preparation method of the large-area perovskite luminescent film has the advantages that the large-area perovskite luminescent film is high in compactness and photoluminescence efficiency, two key steps of solvent volatilization of a wet film and thermal annealing crystallization of the perovskite film can be separated through vacuum pretreatment, so that the control of crystallization kinetics in the preparation process of the perovskite luminescent film is realized, and the problem that a uniform large-area perovskite luminescent layer cannot be prepared by a traditional spin coating process is solved.

(2) The invention prepares the large-area perovskite luminescent film with smooth and compact surface, uniform thickness and high photoluminescence efficiency, and simultaneously prepares the large-area perovskite light-emitting diode with uniform luminescence and high external quantum efficiency on the basis of the printing preparation process of the large-area perovskite luminescent film.

Drawings

FIG. 1 is a schematic view of a printing preparation method of a perovskite light-emitting layer of example 1;

FIG. 2 shows different molar ratios of PEABr to CsPbBr obtained in example 1₃SEM image of the perovskite thin film of (a);

FIG. 3 is an SEM image of the resulting perovskite thin film of example 1;

FIG. 4 is an SEM image of a perovskite thin film produced in comparative example 1;

FIG. 5 is an SEM image of a perovskite thin film produced in comparative example 2;

FIG. 6 is an SEM image of a perovskite thin film produced in comparative example 3;

FIG. 7 is a graph of photoluminescence external quantum efficiency of thin films of perovskite thin films prepared in example 2 and comparative examples 1 to 3;

FIG. 8 is a schematic structural view of a perovskite LED device of example 4;

wherein 1-transparent conductive substrate, 2-hole transport layer, 3-perovskite luminescent layer, 4-electron transport layer, and 5-metal electrode;

FIG. 9 shows different molar ratios of PEABr to CsPbBr obtained in example 4₃The electroluminescent external quantum efficiency curve of the perovskite LED device of (a);

FIG. 10 shows the printing preparation of example 4 for a large area (3.5X 3.5 cm)²) And flexibility (1X 1 cm)²) Luminescence photographs of perovskite LED devices.

Detailed Description

The present invention will be described in further detail with reference to examples and drawings, but the present invention is not limited thereto.

Example 1

Preparation of different molar ratios of PEABr to CsPbBr₃Large area perovskite thin film of (a):

(1) preparing a perovskite precursor solution:

reacting CsBr and PbBr₂Dissolved in DMSO in an equimolar ratio of organic solvent (CsBr ═ 0.3M, PbBr)₂0.3M), mixed well and then dispensed into five bottles of 1mL solution to prepare a 0.3M perovskite solution. Then adding CsPbBr to the five bottles of solution respectively₃The molar proportions of the solutions were 0%, 20%, 40%, 60% and 80% PEABr, giving solutions containing different molar Proportions of (PEA)_m(Cs)_n-1Pb_nBr_3n+1Precursor solution of perovskite type.

(2) With different values of n (PEA)_m(Cs)_n-1Pb_nBr_3n+1The preparation method of the large-area perovskite thin film of the perovskite type is shown in figure 1:

in a glove box with the room temperature of 19 ℃, setting the height difference between a scraper and a substrate to be 220 mu m, dropwise adding 26 mu L of perovskite precursor solution onto a glass substrate, setting the scraping speed to be 3000 mu m/s, and printing and coating the solution on a cleaned ITO glass substrate to obtain a precursor liquid film; putting the precursor liquid film into a vacuum chamber, pumping at the temperature of 19 ℃ at the speed of 150Pa/s to enable the vacuum degree of the vacuum chamber to reach 1100Pa, keeping for 20 seconds, and removing excessive solvent to obtain a pre-crystallized perovskite luminescent film; and (3) annealing the obtained pre-crystallized perovskite luminescent film at 70 ℃ for 1min on a heating table to obtain perovskite luminescent films with different morphologies as shown in figure 2.

Example 2

(1) Preparing a perovskite precursor solution:

0.5mol CsBr and 0.5mol PbBr were added₂Dissolving in DMSO organic solvent, mixing, and adding PbBr₂PEABr in a molar ratio of 40% to give a value of n of 5 (PEA)₂(Cs)₄Pb₅Br₁₆Precursor solution of perovskite type.

(2) n has a value of 5 (PEA)₂(Cs)₄Pb₅Br₁₆The preparation method of the perovskite thin film with large area is as described in example 1: the perovskite film is as shown in figure 3, the film is compact and uniform, and the photoluminescence efficiency is high. The photoluminescence efficiency was as high as 32.3% as shown in fig. 7.

Comparative example 1

Compared with the embodiment 2, the other experimental data and the material dosage are the same, after the liquid film is coated, the perovskite luminescent film is directly heated, annealed and crystallized, the shape of the obtained perovskite luminescent film is shown in figure 4, the film is not uniform, 3-dimensional large particles are generated, the photoluminescence quantum efficiency is only 0.78% as shown in figure 7, and the film basically does not emit light.

Comparative example 2

Compared with the example 2, other experimental data and material consumption are the same, after the liquid film is coated, the perovskite film is naturally dried at room temperature and then crystallized by heating and annealing, the shape of the obtained perovskite film is shown in figure 5, the film is not uniform, holes are generated, the photoluminescence quantum efficiency of the film is 6.8 percent as shown in figure 7, and the luminous efficiency is very low.

Comparative example 3

Compared with the embodiment 2, the comparative example has the same other experimental data and material dosage, and after the liquid film is coated, the perovskite thin film obtained by vacuum treatment has the appearance shown in fig. 6, the compactness of the thin film is good, but the photoluminescence quantum efficiency is 17 percent shown in fig. 7 and is half of the luminous efficiency of the embodiment 2.

From fig. 7, which is a graph showing external photoluminescence quantum efficiencies of thin films of perovskite thin films prepared in example 2 and comparative examples 1 to 3, the perovskite thin films prepared by vacuum post-annealing had the highest photoluminescence quantum efficiency.

Example 3

Preparation of mixtures containing different molar ratios of PEABr to FAPBBr₃Large area perovskite thin film of (a):

(1) preparing a perovskite precursor solution:

adding FABr and PbBr₂In an equimolar ratio in an organic solvent of NMP (CsBr ═ 0.4M, PbBr)₂0.4M), mixed well and then dispensed into five bottles of 1mL solution to prepare a 0.5M perovskite solution. Respectively adding FAPBBr into the five bottles of solution₃The molar proportions of the solutions were 0%, 20%, 40%, 60% and 80% PEABr, giving different values of n (PEA)_m(FA)_n-1Pb_nBr_3n+1Precursor solution of perovskite type.

(2) With different values of n (PEA)_m(FA)_n-1Pb_nBr_3n+1The large area perovskite thin film of (a) was prepared in the manner described in example 1.

Example 4

Preparation of a large area perovskite LED device, comprising the preparation process of the large area perovskite luminescent thin film described in example 1:

the invention relates to a perovskite LED device with a multilayer structure, which comprises a glass substrate containing ITO, a hole transport layer, a perovskite luminescent layer, an electron transport layer and an electrode from bottom to top in sequence (wherein, the preparation processes of the hole transport layer and the perovskite luminescent layer adopt the printing preparation process of embodiment 1), the structural diagram of the device is shown in figure 8,

(1) a glass substrate with ITO or a conductive flexible substrate is used.

The step of cleaning the substrate is: and respectively ultrasonically cleaning the substrate for 5-30min by using washing liquor, deionized water, isopropanol and ethanol, and treating organic matters, impurities and the like on the surface through a cleaning step. The cleaned substrate is then placed in an oven to dry for use. And (3) carrying out ultraviolet oxygen treatment on the dried ITO-bearing glass substrate or the dried conductive flexible substrate in plasma for 10 min.

Preferably, the substrate herein is also selected to be an FTO rigid substrate.

(2) Preparation of NiO_xA hole transport layer.

20mL of ethanol, 30. mu.L of ethanolamine and 500mg of nickel acetate were mixed in a suitable reagent bottle and filtered through an aqueous filter head with a filter diameter of 0.35. mu.m. Printing the filtered solution on a cleaned substrate at the speed of 3mm/s, and heating at 400 ℃ for 30min by using a hot bench to obtain NiO_xA hole transport layer.

Preferably, the hole transport layer material here may also be PEDOT PSS, poly [ bis (4-phenyl) (2,4, 6-trimethylphenyl) amine](PTAA) or alumina (Al)₂O₃) At least one of (1).

(3) The perovskite light emitting layer was prepared as described in example 1.

(4) And preparing an electron transport layer.

After the perovskite luminescent layer is prepared, the ITO glass substrate is placed into an organic-inorganic evaporation chamber, and the vacuum degree is reduced to 3.0 multiplied by 10^-6Pa, TPBi with the thickness of 30nm and LiF with the thickness of 10nm are deposited in sequence at the speed of 0.1nm/s to be used as electron transport layers.

Preferably, the electron transport layer material here can also be zinc oxide (ZnO) or molybdenum trioxide (MoO)₃) At least one of (1).

(5) And preparing an aluminum electrode.

After the electron transport layer is deposited, the metallic aluminum is put into an organic-inorganic evaporation chamber, and the vacuum degree is reduced to 3.0 multiplied by 10^-6Pa, 100nm thick aluminum electrode was deposited at a rate of 0.1 nm/s.

FIG. 9 is a graph of the external quantum efficiency of light emitting diodes prepared with different PEABr contents, and FIG. 10 is a graph of the external quantum efficiency of light emitting diodes prepared with an area of 3.5X 3.5cm²And luminescence photographs of flexible perovskite LED devices.

Preferably, the electrode material here may also be at least one of Ag or Au.

The above embodiments are preferred embodiments of the present invention, but the present invention is not limited to the above embodiments, and any other changes, modifications, substitutions, combinations, and simplifications which do not depart from the spirit and principle of the present invention should be construed as equivalents thereof, and all such changes, modifications, substitutions, combinations, and simplifications are intended to be included in the scope of the present invention.