CN108807724B

CN108807724B - Preparation method and application of perovskite luminescent layer, perovskite luminescent device and preparation method thereof

Info

Publication number: CN108807724B
Application number: CN201810614923.4A
Authority: CN
Inventors: 李波波; 张昭宇; 刘浩霖; 方铉
Original assignee: Chinese University of Hong Kong CUHK
Current assignee: Chinese University of Hong Kong CUHK
Priority date: 2018-06-14
Filing date: 2018-06-14
Publication date: 2020-10-16
Anticipated expiration: 2038-06-14
Also published as: CN108807724A

Abstract

The invention discloses a preparation method and application of a perovskite luminescent layer, a perovskite luminescent device and a preparation method thereof, and relates to the technical field of electroluminescent devices.A preparation method of a perovskite luminescent layer comprises the following steps of spin coating 2-5 layers with the concentration of (1-3) × 10^‑ ⁶mol/L CsPbX₃The invention solves the technical problem that in the prior art, high-concentration perovskite dispersion liquid is directly spun in a spinning mode during preparation of the perovskite luminescent layer, quantum dot agglomeration is easy to occur in the film forming process, and the photoelectric property of the perovskite dispersion liquid is influenced, and the invention obtains the perovskite luminescent layer by spinning 2-5 layers of low-concentration (1-3) × 10^‑6mol/L CsPbX₃The perovskite quantum dot dispersion liquid can effectively avoid the excessive agglomeration of quantum dots, so that the photoelectric conversion performance of a perovskite LED device can be improved, and meanwhile, the method is very simple to operate and has good repeatability.

Description

Preparation method and application of perovskite luminescent layer, perovskite luminescent device and preparation method thereof

Technical Field

The invention relates to the technical field of electroluminescent devices, in particular to a preparation method and application of a perovskite luminescent layer, a perovskite luminescent device and a preparation method thereof.

Background

Most of the current intelligent hardware products have entered a steady development stage, but the technology related to the display screen has been continuously advanced through various ways. Compared with the LCD, the OLED has many advantages, such as active light emission, no viewing angle, light weight, small thickness, high brightness, high light emitting efficiency, abundant light emitting materials, easy color display, fast response speed, high dynamic picture quality, wide temperature range, flexible display, simple process, low cost, and strong shock resistance, and is called as an ideal display in the future. One of the development demands of OLEDs is to find a luminescent material that is cheaper, simple in preparation process, and excellent in performance.

In recent years, organic-inorganic hybrid perovskites (ABX)₃A represents an organic ammonium cation or an inorganic metal cation, such as CH₃NH₃ ⁺、HC(NH₂)₂ ⁺And Cs⁺Etc., B represents a divalent metal ion, such as Pb²⁺、Sn²⁺Etc., X represents a halide ion, such as I^-、Cl^-、Br^-Etc.) have become a new generation of star semiconductor materials due to their excellent optoelectronic properties, and have attracted considerable attention from researchers. The perovskite material has high light absorption coefficient (105), wide light absorption spectrum (200-1000 nm), adjustable band gap (1.5-2.2 eV), long carrier diffusion length (100-1000 nm), and high carrier mobility (12.5-66 cm)²V.s) and exciton binding energy is low (50-76 m eV); in addition, the material has the advantages of simple preparation process, low price and the like. These advantages determine that the perovskite material can be widely applied to the fields of solar cells, light emitting diodes, photodetectors, lasers and the like, and the perovskite material has the characteristics of being capable of emitting a wide spectrum and being adjustable in light color, and is gradually one of the most potential luminescent materials in the field of OLEDs.

In 2014, Tan et al prepared FTO/TiO by using low-temperature solution method₂/CH₃NH₃PbI_3－xCl_xthe/F8/Au type perovskite device not only overcomes the problems of liquid nitrogen, high voltage and the like, but also obtains a near-infrared perovskite OLED device with high brightness; next, researchers optimized the structure of perovskite LED devices by using different electron or hole transport layers, such that the External Quantum Efficiency (EQE) of the devices increased to around 0.5%; researchers regulate and control the perovskite luminescent layer, report a series of LED devices based on nano perovskite materials, Zhang et al prepare perovskite quantum dots by a ligand-assisted redeposition method, realize photoluminescence in a visible light range of 405-730 nm, and prove that the small perovskite quantum dots have higher fluorescence quantum efficiency; recently, Wangjiapu et al introduced a quantum well structure for improving the light emitting efficiency of a device in an inorganic LED into a perovskite LED by a solution processing method, and developedThe perovskite luminescent material with a multi-quantum well structure is utilized, and the external quantum efficiency of the OLED device prepared by the perovskite material with the adjustable dimensionality can reach more than 12%. In addition, materials with different band gaps can be obtained by regulating and controlling the composition (including organic groups, halogen atom proportion and the like) and the morphology (different temperatures, solvent treatment) and the like of the perovskite, so that multicolor luminescence of the perovskite material from near infrared light to visible light is realized.

In the prior art, a perovskite quantum dot dispersion liquid is obtained by spin coating when a perovskite luminescent layer is prepared, but the perovskite dispersion liquid with high concentration is directly spin-coated, so that the quantum dot agglomeration phenomenon is easy to occur in the film forming process, the photoelectric property of the perovskite dispersion liquid is influenced, in order to avoid the agglomeration, a complex chemical treatment process is generally required to be carried out on the quantum dot, and the operation is complex.

It is therefore desirable to provide a method of producing a perovskite light-emitting layer which is capable of solving at least one of the above-mentioned problems.

In view of the above, the present invention is particularly proposed.

Disclosure of Invention

One of the purposes of the invention is to provide a preparation method of a perovskite luminescent layer, mainly by spin coating 2-5 layers of low-concentration (1-3) × 10^-6CsPbX of M₃The perovskite quantum dot dispersion liquid has low concentration, can effectively avoid the agglomeration of quantum dots, and spin coating of multiple layers (2-5 layers) of perovskite can improve the carrier composite concentration in a luminescent layer, thereby improving the photoelectric conversion performance of a perovskite device.

The invention also aims to provide an application of the preparation method of the perovskite luminescent layer in preparation of a perovskite luminescent device.

The perovskite luminescent layer prepared by the preparation method of the perovskite luminescent layer has the same advantages as the perovskite luminescent layer and is good in photoelectric conversion performance.

The fourth purpose of the present invention is to provide a method for manufacturing the above perovskite light emitting device, which is convenient for operation.

In order to achieve the above purpose of the present invention, the following technical solutions are adopted:

in a first aspect, there is provided a method of fabricating a perovskite light emitting layer, comprising the steps of:

spin coating 2-5 layers with concentration of (1-3) × 10^-6mol/L CsPbX₃And obtaining the perovskite luminescent layer by using the perovskite quantum dot dispersion liquid.

Preferably, on the basis of the technical scheme of the invention, the CsPbX is adopted₃The concentration of the perovskite quantum dot dispersion liquid is (1-2) × 10^-6mol/L, preferably 1 × 10^-6mol/L; the number of spin-coating layers is 3 to 5, preferably 4.

Preferably, on the basis of the technical scheme of the invention, the spin-coating rotating speed of each layer of spin coating is 2000-4000rpm independently; the spin coating time for each layer of spin coating was independently 30-50 s.

Preferably, on the basis of the technical scheme of the invention, CsPbX₃X in (3) is any one or combination of any two of I, Cl or Br;

preferably, the CsPbX₃The solvent adopted by the perovskite quantum dot dispersion liquid is n-octane or tetrahydrofuran.

In a second aspect, the application of the preparation method of the perovskite luminescent layer in the preparation of a perovskite luminescent device is provided.

In a third aspect, a perovskite light emitting device is provided, which comprises the perovskite light emitting layer prepared by the preparation method of the perovskite light emitting layer.

Preferably, on the basis of the technical scheme of the invention, the light-emitting device is a light-emitting diode;

preferably, the perovskite light emitting diode comprises a substrate, a hole transport layer, the perovskite light emitting layer, an electron transport layer and an electrode material, wherein the hole transport layer, the perovskite light emitting layer, the electron transport layer and the electrode material are sequentially deposited on the surface of the substrate;

preferably, the substrate is an ITO substrate;

preferably, the hole transport material of the hole transport layer comprises one or a combination of at least two of poly (p-phenylene vinylenes), polythiophenes, polysilanes, triphenylmethanes, triarylamines, hydrazones, pyrazolines, carbazoles, or butadienes, preferably poly (ethylenedioxythiophene) -poly (styrenesulfonate);

preferably, the electron transport material of the electron transport layer comprises one or a combination of at least two of 1,3, 5-tris (1-phenyl-1H-benzimidazol-2-yl) benzene, 4, 7-diphenyl-1, 10-phenanthroline or zinc oxide, preferably 1,3, 5-tris (1-phenyl-1H-benzimidazol-2-yl) benzene;

preferably, the electrode material is any one of LiF/Al or Ag.

In a fourth aspect, a method for manufacturing a perovskite light emitting device is provided, wherein the light emitting device is a light emitting diode, and the method for manufacturing the perovskite light emitting diode comprises the following steps:

and sequentially preparing a hole transport layer, the perovskite luminescent layer, an electron transport layer and an electrode material on the substrate to obtain the perovskite light-emitting diode.

Preferably, on the basis of the technical scheme of the invention, the preparation method of the perovskite light-emitting device comprises the following steps:

(a) cleaning the substrate;

(b) spin-coating a hole transport layer solution on the cleaned substrate, and performing heat treatment to obtain a hole transport layer;

(c) spin-coating 2-5 layers of × 10 (1-3) concentration on the hole transport layer obtained in step (b)^-6mol/L CsPbX₃Obtaining a perovskite luminescent layer by using the perovskite quantum dot dispersion liquid;

(d) and (c) depositing an electron transport layer on the perovskite luminescent layer obtained in the step (c), and then depositing an electrode material to obtain the perovskite luminescent diode.

Preferably, on the basis of the technical solution of the present invention, the cleaning conditions in step (a) include: sequentially ultrasonically cleaning with water, ketone and alcohol solvent for 10-20min, drying, and treating with plasma for 5-10 min;

preferably, the spin coating thickness in the step (b) is 30-60nm, further preferably, the spin coating rotation speed is 2000-4000rpm, and the spin coating time is 30-50 s; preferably, the heat treatment temperature is 100-;

preferably, the spin-coating rotation speed of each layer of spin-coating in the step (c) is independently 2000-4000 rpm; the spin coating time of each layer of spin coating is independently 30-50 s;

preferably, the electron transport layer is deposited and the electrode material is deposited in step (d) independently by thermal evaporation or magnetron sputtering, more preferably by thermal evaporation;

preferably, the electron transport layer has an evaporation rate of

The evaporation thickness is 30-50 nm;

preferably, the evaporation rate of the electrode material is

The evaporation thickness is 1-100 nm.

Compared with the prior art, the invention has the following beneficial effects:

(1) the preparation method of the perovskite luminescent layer provided by the invention mainly comprises the steps of spin coating 2-5 layers of low-concentration (1-3) × 10^-6CsPbX of M₃The (X represents I, Cl or Br, etc.) perovskite quantum dot dispersion liquid has low concentration, can effectively avoid the agglomeration of quantum dots, and the spin coating of a plurality of layers (2-5 layers) of perovskite can improve the carrier recombination concentration in a light-emitting layer, thereby improving the photoelectric conversion performance of a perovskite device.

(2) The method has the advantages of simple operation and good repeatability, avoids the complex process of chemically processing the quantum dots, and can effectively improve the photoelectric conversion performance of the perovskite device only by a method of spin-coating the low-concentration perovskite quantum dot light-emitting layer for multiple times.

(3) The photoelectric conversion performance test result of the multilayer low-concentration perovskite quantum dot LED manufactured by the perovskite luminous layer manufacturing method provided by the invention shows that the external quantum conversion efficiency of the perovskite quantum dot LED device is increased and then decreased along with the increasing of the number of luminous layers, when the number of spin-coating layers is 4, the performance of the device is optimal, the maximum conversion efficiency can reach more than 1.5%, and compared with a single-layer perovskite quantum dot LED, the performance is improved by 3 times.

Drawings

FIG. 1 is a schematic structural view of a perovskite LED device according to one embodiment of the present invention;

fig. 2 is an external quantum efficiency curve for the perovskite LED device of example 1, wherein the photograph is a photograph of the luminescence of the device at maximum brightness.

Detailed Description

Embodiments of the present invention will be described in detail below with reference to examples, but it will be understood by those skilled in the art that the following examples are only illustrative of the present invention and should not be construed as limiting the scope of the present invention. The examples, in which specific conditions are not specified, were conducted under conventional conditions or conditions recommended by the manufacturer. The reagents or instruments used are not indicated by the manufacturer, and are all conventional products available commercially.

According to a first aspect of the present invention there is provided a method of fabricating a perovskite light emitting layer comprising the steps of spin coating 2 to 5 layers at a concentration of (1 to 3) × 10^-6mol/L CsPbX₃And obtaining the perovskite luminescent layer by using the perovskite quantum dot dispersion liquid.

CsPbX₃X in Perovskite quantum dots (Perovskite QDs) is typically, but not limited to, I, Cl or Br, for example.

CsPbX₃The perovskite quantum dot dispersion liquid is CsPbX₃The perovskite quantum dots are dispersed in a solvent, and the solvent includes but is not limited to n-octane, tetrahydrofuran or the like.

When the perovskite luminescent layer is obtained by the traditional spin coating of perovskite quantum dot dispersion liquid, the high concentration (the concentration is generally more than 10) is directly spin-coated^-6M), but the aggregation phenomenon of quantum dots is easy to occur in the film forming process, the photoelectric property of the perovskite is influenced, and in order to avoid the aggregation, a more complex chemical treatment process is generally required to be carried out on the quantum dots.

The invention adopts spin coating to form 2-5 layers with the concentration of (1-3) × 10^-6mol/L CsPbX₃The perovskite quantum dot dispersion can effectively improve the problem.

CsPbX₃Perovskite quantumThe concentration of the dot dispersion was (1-3) × 10^-6mol/L, e.g. 1 × 10^-6mol/L、2×10^-6mol/L or 3 × 10^-6mol/L, the number of spin-coating layers is 2-5, for example 2, 3, 4 or 5.

Low concentration (1-3) × 10 by spin coating^-6CsPbX of M₃The perovskite quantum dot dispersion liquid can effectively avoid the agglomeration of quantum dots, the composite concentration of current carriers in the luminescent layer can be improved by spin coating multiple layers (2-5 layers) of the perovskite quantum dot dispersion liquid, and the photoelectric conversion performance of the perovskite device can be effectively improved by preparing the perovskite luminescent layer by the method. In addition, the method avoids the complex process of chemically processing the quantum dots, can effectively improve the photoelectric conversion performance of the perovskite device only by a method of spin-coating the low-concentration perovskite quantum dot light-emitting layer for multiple times, and is very simple and good in repeatability.

In a preferred embodiment, CsPbX₃The concentration of the perovskite quantum dot dispersion liquid is (1-2) × 10^-6mol/L, preferably 1 × 10^-6mol/L; the number of spin-coating layers is 3 to 5, preferably 4.

By further optimizing the concentration of the perovskite quantum dot dispersion and the number of spin-coating layers, a perovskite device having excellent photoelectric conversion performance can be obtained.

The spin coating condition is not limited, and the spin coating can be carried out by adopting a conventional spin coating mode; preferably, the spin-coating rotation speed of each layer of spin coating is 2000-4000rpm independently; the spin coating time for each layer of spin coating was independently 30-50 s.

The spin-coating rotation speed of each layer of spin coating is, for example, 2000rpm, 3000rpm or 4000 rpm; the spin coating time for each layer is, for example, 30s, 40s or 50 s.

By controlling the spin-coating speed and time, the agglomeration of the quantum dots can be further prevented.

According to a second aspect of the present invention there is provided the use of a method of making a perovskite light-emitting layer as described above in the manufacture of a perovskite light-emitting device.

Typical, but not limiting examples of the light emitting device are a Cathode Ray Tube (CRT), a vacuum fluorescent tube (VFD), a glow discharge tube (GDD), a Liquid Crystal Display (LCD), a Plasma Display Panel (PDP), a Light Emitting Diode (LED), a Field Emission Display (FED), an electroluminescence display (ECD), an electrochromic display (ECD), a laser display (LPD), an electrophoresis display (EPD), a ferro-ceramic display (PLZT), etc., and it is preferably applied to a perovskite LED device.

The method can effectively prevent the quantum dots from agglomerating, and the prepared perovskite luminescent layer has good luminescent property, so that the method can be applied to the preparation of perovskite luminescent devices and can obviously improve the photoelectric conversion performance of the perovskite devices.

According to a third aspect of the present invention, there is provided a perovskite light emitting device comprising the perovskite light emitting layer prepared by the above-described method of preparing a perovskite light emitting layer.

The perovskite luminescent device has the same advantages as the perovskite luminescent layer, and the perovskite luminescent device has good photoelectric conversion performance.

Typical but non-limiting examples of light emitting devices are CRT, VFD, GDD, LCD, PDP, LED, FED, ECD, LPD, EPD or PLZT, etc.

Preferably, the light emitting device is a light emitting diode.

Preferably, a typical perovskite light emitting diode comprises a substrate, a hole transport layer, the perovskite light emitting layer, an electron transport layer and an electrode material, wherein the hole transport layer, the perovskite light emitting layer, the electron transport layer and the electrode material are sequentially deposited on the surface of the substrate.

The substrate is typically, but not limited to, an ITO substrate.

The hole transport layer is a layer structure formed by hole transport materials, and the hole transport materials are semiconductor materials which can realize the directional ordered controlled migration of carriers under the action of an electric field when the carriers (electrons or holes) are injected, so that the charge is transported. Typical but non-limiting hole transport materials are, for example, poly (p-phenylenes), polythiophenes, polysilanes, triphenylmethanes, triarylamines, hydrazones, pyrazolines, carbazoles, or butadienes, and the like, preferably poly (ethylenedioxythiophene) -poly (styrenesulfonate) (PEDOT: PSS).

Here, "the perovskite light-emitting layer" refers to a perovskite light-emitting layer obtained by the method for producing a perovskite light-emitting layer of the first aspect of the present invention, as described above.

The electron transport layer is a layer structure composed of an electron transport material for transporting electrons, and the electron transport material is typically, but not limited to, 1,3, 5-tris (1-phenyl-1H-benzimidazol-2-yl) benzene (TPBI for short), 4, 7-diphenyl-1, 10-phenanthroline (Bphen for short), zinc oxide, or the like.

The electrode material is not limited, and any electrode material conventional in the art may be used, such as LiF/Al or Ag, typically but not limited thereto.

The perovskite light-emitting diode with the typical structure has good photoelectric conversion performance, and has better photoelectric conversion performance compared with the traditional method of preparing a light-emitting layer by spin coating of high-concentration perovskite quantum dot dispersion liquid.

According to a fourth aspect of the present invention, there is provided a method of manufacturing a perovskite light emitting diode of the above structure, comprising the steps of:

Preferably, the method for preparing the perovskite light emitting diode with the structure comprises the following steps:

(a) cleaning the substrate;

The description of the substrate, hole transport layer, perovskite light emitting layer, electron transport layer and electrode material is in accordance with the corresponding description in the third aspect of the invention described above.

Preferably, the washing conditions in step (a) include: sequentially ultrasonic cleaning with water, ketone and alcohol solvent for 10-20min, drying, and treating with plasma for 5-10 min.

The water is preferably deionized water, the ketones are preferably acetone, and the alcohols are preferably isopropanol.

The ultrasonic cleaning time includes, but is not limited to, 10min, 15min or 20 min.

The drying is preferably blown dry with nitrogen, the plasma treatment time being, for example, 5min, 8min or 10 min.

Preferably, the spin-coating thickness in step (b) is from 30 to 60nm, for example 30nm, 40nm, 50nm or 60 nm.

Preferably, the spin-coating speed is 2000-4000rpm, such as 2000rpm, 3000rpm or 4000 rpm; the spin coating time is 30-50s, for example 30s, 40s or 50 s;

preferably, the heat treatment temperature is 100-; the annealing time is 10-30min, for example 10min, 20min or 30 min.

Preferably, the spin-coating rotation speed of each layer of spin-coating in the step (c) is independently 2000-4000 rpm; the spin coating time for each layer of spin coating was independently 30-50 s.

preferably, the electron transport layer has an evaporation rate of

For example

Or

The evaporation thickness is 30-50nm, such as 30nm, 40nm or 50 nm.

Preferably, the evaporation rate of the electrode material is

For example

Or

The evaporation thickness is 1-100nm, such as 1nm, 2nm, 5nm, 10nm, 20nm, 30nm, 50nm or 100 nm.

In a preferred embodiment, a method for preparing a perovskite light emitting diode having the above structure typically includes the steps of:

(a) cleaning an ITO substrate: respectively ultrasonically cleaning an ITO substrate in deionized water, acetone and isopropanol for 10-20min, finally blowing nitrogen gas to dry, and treating for 5-10min with Plasma;

(b) preparing a hole transport layer: filtering the hole transport layer solution through a water filter head, spin-coating for 30-50s under the conditions of 2000-;

(c) preparing a perovskite luminous layer: CsPbX is firstly added₃Dispersing perovskite quantum dots in tetrahydrofuran solution, standing the dispersion solution for more than 24 hours, taking supernatant fluid to spin-coat and make a membrane, wherein the concentration of the supernatant fluid is (1-3) × 10^-6mol/L, spin coating 2-5 layers, and obtaining by superposing one layer of spin coating on another layer, wherein the spin coating conditions of each layer are consistent, namely the spin coating rotation speed is 2000 and 4000rpm, and the spin coating time is 30-50 s;

(d) and (c) depositing an electron transport layer on the perovskite luminescent layer obtained in the step (c) through vacuum evaporation, and then depositing an electrode material to obtain the perovskite luminescent diode.

The invention is further illustrated by the following specific examples and comparative examples, but it should be understood that these examples are for purposes of illustration only and are not to be construed as limiting the invention in any way. All the raw materials related to the invention can be obtained commercially.

Example 1

A preparation method of a perovskite light emitting diode comprises the following steps:

(1) cleaning an ITO substrate: respectively ultrasonically cleaning an ITO substrate in deionized water, acetone and isopropanol for 15 minutes, finally blowing the ITO substrate by nitrogen and treating the ITO substrate by Plasma for 8 minutes;

(2) preparing a hole transport layer: filtering the PSS solution with a 0.22-micron water filter head, spin-coating at 3000rpm for 40s to obtain the PEDOT, annealing at 130 deg.C for 20min, and transferring into a nitrogen atmosphere glove box;

(3) preparing a perovskite luminous layer: CsPbBr is firstly added₃Dispersing perovskite quantum dots in tetrahydrofuran solution, standing the dispersion for more than 24 hours, and taking supernatant (the concentration of the supernatant quantum dots is 1 × 10)^-6M) spin coating to prepare a film, wherein the number of spin coating layers is 4, the spin coating layers are obtained by overlapping the spin coating layers, and the spin coating conditions of each layer are consistent, namely the spin coating speed is 3000rpm, and the spin coating time is 40 s;

(4) preparing an electron transport layer: depositing a TPBI layer by vacuum evaporation at a rate of

The evaporation thickness is 30 nm;

(5) preparing an electrode: depositing LiF and Al electrodes by vacuum evaporation, the evaporation rate of LiF being

The thickness of the evaporation coating is 1nm, and the evaporation coating rate of Al is

The thickness of the vapor deposition is 100nm, and the structure of the obtained perovskite light-emitting diode is shown in figure 1.

Example 2

(1) cleaning an ITO substrate: respectively ultrasonically cleaning an ITO substrate in deionized water, acetone and isopropanol for 10 minutes, finally blowing the ITO substrate by nitrogen and treating the ITO substrate by Plasma for 10 minutes;

(2) preparing a hole transport layer: filtering the PSS solution by a 0.22-micron water filter head, spin-coating for 30s at 4000rpm, annealing at 100 ℃ for 30min, and transferring to a nitrogen atmosphere glove box;

(3) preparing a perovskite luminous layer: CsPbI first₃Dispersing perovskite quantum dots in tetrahydrofuran solution, standing the dispersion for more than 24 hours, and taking supernatant (the concentration of the supernatant quantum dots is 1 × 10)^-6M) spin coating to prepare a film, wherein the number of spin coating layers is 4, the spin coating layers are obtained by overlapping the spin coating layers, and the spin coating conditions of each layer are consistent, namely the spin coating speed is 4000rpm, and the spin coating time is 30 s;

The evaporation thickness is 50 nm;

The deposition thickness is 2nm, and the deposition rate of Al is

The evaporation thickness was 75 nm.

Example 3

(1) cleaning an ITO substrate: respectively ultrasonically cleaning an ITO substrate in deionized water, acetone and isopropanol for 20 minutes, finally blowing the ITO substrate by nitrogen and treating the ITO substrate by Plasma for 5 minutes;

(2) preparing a hole transport layer: filtering the PSS solution with a 0.22-micron water filter head, spin-coating at 2000rpm for 50s to obtain the PEDOT, annealing at 140 ℃ for 15min, and transferring into a nitrogen atmosphere glove box;

(3) preparing a perovskite luminous layer: CsPbCl is firstly added₃Dispersing perovskite quantum dots in tetrahydrofuran solution, standing the dispersion for more than 24 hours, and taking supernatant (the concentration of the supernatant quantum dots is 1 × 10)^-6M) spin coating to prepare a film, wherein the number of spin coating layers is 4, and the film is formed by one layerThe layers are obtained by overlapping the spin coating, and the spin coating conditions of each layer are consistent, namely the spin coating rotating speed is 2000rpm, and the spin coating time is 50 s;

The evaporation thickness is 40 nm;

The thickness of the evaporation coating is 3nm, and the evaporation coating rate of Al is

The thickness of the vapor deposition is 50 nm.

Example 4

This example is different from example 1 in that the number of spin-coated layers in step (3) was replaced with 2 layers, and other conditions were kept the same to produce a perovskite light emitting diode.

Example 5

This example is different from example 1 in that the number of spin-coated layers in step (3) was replaced with 3 layers, and other conditions were kept the same to produce a perovskite light emitting diode.

Example 6

This example is different from example 1 in that the number of spin-coated layers in step (3) was replaced with 5 layers, and other conditions were kept the same to produce a perovskite light emitting diode.

Example 7

This example differs from example 1 in that CsPbBr in step (3) is added₃Replacement by CsPbCl_xBr_3-x(x ranges from 0 to 3), and other conditions are kept consistent to prepare the perovskite light-emitting diode.

Example 8

This example differs from example 1 in that CsPbBr in step (3) is added₃Replacement by CsPbI_xBr_3-x(x ranges from 0 to 3), other conditions are kept consistent,and manufacturing the perovskite light-emitting diode.

Example 9

This example differs from example 1 in that the TPBI in step (4) was replaced with Bphen, and other conditions were kept consistent to produce a perovskite light emitting diode.

Example 10

This example differs from example 1 in that the perovskite light emitting diode was produced by replacing TPBI in step (4) with ZnO and keeping the other conditions the same.

Comparative example 1

This example is different from example 1 in that the number of spin-coated layers in step (3) was replaced with 1 layer, and other conditions were kept the same to produce a perovskite light emitting diode.

Comparative example 2

This example differs from example 1 in that step (3) is replaced with CsPbBr₃The perovskite quantum dots are dispersed in tetrahydrofuran solution, and the concentration of the dispersion liquid is 1.27 × 10^-4And M, spin-coating to prepare a film, wherein the spin-coating rotation speed is 3000rpm, the spin-coating time is 40s, and other conditions are kept consistent to prepare the perovskite light-emitting diode.

Test examples

In order to examine the effects of the perovskite light emitting diodes obtained in the examples and comparative examples, the following tests were performed:

an integrating sphere test system is used for testing the photoelectric conversion performance (an electroluminescence spectrum EL, a current-voltage curve and an external quantum efficiency EQE) of the perovskite OLED, the test voltage range is 0-10V, the maximum limit of the current is 20mA, and the integration time of the electroluminescence spectrum is 8 ms.

The highest external quantum efficiency of the device was recorded and the results are shown in table 1.

TABLE 1

Examples or comparative examples	Highest outer layerQuantum efficiency
		Example 1	1.5％
Example 2	1.3％
		Example 3	1.6％
Example 4	1.0％
		Example 5	1.2％
Example 6	1.3％
		Example 7	1.4％
Example 8	1.5％
		Example 9	1.5％
Example 10	1.4％
		Comparative example 1	0.5％
Comparative example 2	0.9％

Fig. 2 is an external quantum efficiency curve for the perovskite LED device of example 1, with a maximum external quantum efficiency of 1.5%.

As can be seen from the results of Table 1 and FIG. 2, the low concentration of CsPbBr was obtained by dispersing and allowing to stand₃The perovskite quantum dot dispersion liquid is spin-coated by a layer-by-layer superposition method to obtain the multi-layer CsPbBr₃Perovskite quantum dot light emitting layer and single-layer CsPbBr₃As a comparison, the quantum dot device (comparative example 1) was tested to find that CsPbBr is a material with good photoelectric conversion performance₃The external quantum conversion efficiency of the perovskite quantum dot LED device shows a trend of increasing and then decreasing along with the increasing of the number of the light emitting layers, when the number of the spin-coating layers is 4, the performance of the device is optimal, the maximum conversion efficiency can reach more than 1.5%, and compared with a single-layer device of a comparative example 1, the performance is improved by 3 times. CsPbBr-based with increasing number of layers (1-4 layers)₃The maximum external quantum efficiency of perovskite LED devices can be increased from the initial 0.5% to 1.5%.

The embodiment 7 and the embodiment 8 change the types of quantum dots, the photoelectric conversion performance of the device is not greatly different, and the embodiment 9 and the embodiment 10 change the types of substances of the electron transport layer, and the photoelectric conversion performance of the device is not obviously influenced.

Compared with the embodiment 1, the method of the invention has the advantages that the photoelectric conversion performance of the device obtained by adopting the high-concentration dispersion liquid to spin once under the same condition is better than that of the device obtained by adopting the traditional high-concentration perovskite quantum dot dispersion liquid to spin, because excessive agglomeration is avoided, the method avoids the complex process of chemically processing the quantum dot, and the photoelectric conversion performance of the perovskite device can be effectively improved only by adopting the method of spin-coating the low-concentration perovskite quantum dot light-emitting layer for multiple times.

The results show that the photoelectric conversion performance of the LED device prepared by spin-coating the multilayer perovskite quantum dots is obviously improved, and the method is simple and easy to operate and has good repeatability.

While particular embodiments of the present invention have been illustrated and described, it would be obvious that various other changes and modifications can be made without departing from the spirit and scope of the invention. It is therefore intended to cover in the appended claims all such changes and modifications that are within the scope of this invention.

Claims

1. A method for preparing a perovskite light-emitting layer is characterized by comprising the following steps:

spin coating 3-5 layers with concentration of (1-2) × 10^-6mol/L CsPbX₃Obtaining a perovskite luminescent layer by using the perovskite quantum dot dispersion liquid; CsPbX₃X in (3) is any one or combination of any two of I, Cl or Br;

the spin coating speed of each layer of spin coating is 2000-4000rpm independently; the spin coating time for each layer of spin coating was independently 30-50 s.

2. The method of producing a perovskite light-emitting layer according to claim 1, wherein the CsPbX is₃The concentration of the perovskite quantum dot dispersion liquid is 1 × 10^-6mol/L; the number of spin-coating layers was 4.

3. The method of producing a perovskite light-emitting layer according to claim 1 or 2, wherein CsPbX is used as the precursor₃The solvent adopted by the perovskite quantum dot dispersion liquid is n-octane or tetrahydrofuran.

4. Use of a process for the preparation of a perovskite light emitting layer as claimed in any one of claims 1 to 3 in the preparation of a perovskite light emitting device.

5. A perovskite light-emitting device comprising the perovskite light-emitting layer produced by the method for producing a perovskite light-emitting layer according to any one of claims 1 to 3.

6. The perovskite light emitting device of claim 5, wherein the light emitting device is a light emitting diode.

7. The perovskite light-emitting device of claim 5, wherein the perovskite light-emitting diode comprises a substrate, a hole transport layer, the perovskite light-emitting layer, an electron transport layer and an electrode material deposited on a surface of the substrate in that order.

8. The perovskite light emitting device of claim 7, wherein the substrate is an ITO substrate.

9. The perovskite light-emitting device according to claim 7, wherein the hole-transporting material of the hole-transporting layer comprises one or a combination of at least two of poly (p-phenylenes), polythiophenes, polysilanes, triphenylmethanes, triarylamines, hydrazones, pyrazolines, carbazoles, or butadienes.

10. The perovskite light-emitting device according to claim 7, wherein the electron-transporting material of the electron-transporting layer comprises one or a combination of at least two of 1,3, 5-tris (1-phenyl-1H-benzimidazol-2-yl) benzene, 4, 7-diphenyl-1, 10-phenanthroline or zinc oxide.

11. The perovskite light-emitting device of claim 10, wherein the electron-transporting material of the electron-transporting layer is 1,3, 5-tris (1-phenyl-1H-benzimidazol-2-yl) benzene.

12. The perovskite light-emitting device according to claim 7, wherein the electrode material is any one of LiF/Al or Ag.

13. A method of manufacturing a perovskite light emitting device as claimed in any one of claims 6 to 12 wherein the light emitting device is a light emitting diode and the method of manufacturing a perovskite light emitting diode comprises the steps of:

14. A method of making a perovskite light emitting device as claimed in claim 13 comprising the steps of:

(a) cleaning the substrate;

(c) spin-coating 3-5 layers of (1-3) × 10 concentration on the hole transport layer obtained in step (b)^-6mol/L CsPbX₃Obtaining a perovskite luminescent layer by using the perovskite quantum dot dispersion liquid;

15. A method of making a perovskite light emitting device as claimed in claim 14 wherein the cleaning conditions in step (a) comprise: sequentially ultrasonic cleaning with water, ketone and alcohol solvent for 10-20min, drying, and treating with plasma for 5-10 min.

16. A method of making a perovskite light emitting device as claimed in claim 14 wherein the spin coating thickness in step (b) is from 30 to 60 nm.

17. The method of preparing a perovskite light emitting device as claimed in claim 16, wherein the spin coating rotation speed is 2000-4000rpm and the spin coating time is 30-50 s.

18. The method of preparing a perovskite light emitting device as claimed in claim 16 wherein the heat treatment temperature is 100 ℃ and 140 ℃ and the annealing time is 10-30 min.

19. The method of fabricating a perovskite light-emitting device as claimed in claim 14 wherein the spin-coating speed of each layer of spin-coating in step (c) is independently 2000-4000 rpm; the spin coating time for each layer of spin coating was independently 30-50 s.

20. A method of making a perovskite light-emitting device as claimed in claim 14 wherein step (d) of depositing the electron-transporting layer and depositing the electrode material are both independently by thermal evaporation or magnetron sputtering.

21. A method of making a perovskite light emitting device as claimed in claim 20 wherein step (d) of depositing the electron transport layer and depositing the electrode material are both independently by thermal evaporation.

22. A method of making a perovskite light emitting device as claimed in claim 21 wherein the electron transport layer is evaporated at a rate of

The thickness of the vapor deposition is 30-50 nm.

23. A method of making a perovskite light emitting device as claimed in claim 22 wherein the electrode material is evaporated at a rate of

The evaporation thickness is 1-100 nm.