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

Abstract

The invention discloses a preparation method and application of a perovskite light-emitting layer, a perovskite light-emitting device and a preparation method thereof, and relates to the technical field of electroluminescence devices. The preparation method of the perovskite light-emitting layer includes the following steps: spin-coating 2-5 layers of CsPbX ₃ perovskite quantum dot dispersion liquid with a concentration of (1-3)× ^10-6 mol ^/ L to obtain the perovskite light-emitting layer. The invention alleviates the technical problem that the quantum dots are easily agglomerated during the film-forming process when the perovskite light-emitting layer is prepared by directly spin-coating the high-concentration perovskite dispersion liquid in the prior art, and the photoelectric performance thereof is affected. The present invention can effectively avoid excessive agglomeration of quantum dots by spin-coating 2-5 layers of low-concentration (1-3)× ^10-6 mol/L CsPbX ₃ perovskite quantum dot dispersion liquid, thereby improving perovskite The photoelectric conversion performance of the LED device, and the method is very simple to operate and has good repeatability.

Description

Preparation method and application of perovskite light-emitting layer and perovskite light-emitting device and preparation thereof method

technical field

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

Background technique

Most of today's smart hardware products have entered a stage of steady development, but the technology of display screens has been constantly improving in various ways. Compared with LCD, OLED has many advantages, such as active light emission, no viewing angle problem, light weight, small thickness, high brightness, high luminous efficiency, rich luminescent materials, easy to achieve color display, fast response speed, high dynamic picture quality, use Wide temperature range, flexible and flexible display, simple process, low cost and strong shock resistance, so it is called the ideal display of the future. One of the development needs of OLEDs is to find light-emitting materials that are cheaper, simpler to prepare and have better properties.

In recent years, organic-inorganic hybrid perovskites (ABX ₃ , A represents organic ammonium cations or inorganic metal cations, such as CH ₃ NH ₃ ⁺ , HC(NH ₂ ) ₂ ⁺ and Cs ⁺ , etc., B represents divalent metal ions , such as Pb ²⁺ , Sn ²⁺ , etc., X represents halide ions, such as I ^- , Cl ^- , Br ^- etc.) because of its excellent optoelectronic properties, it has gradually become a new generation of star semiconductor materials, which has attracted extensive attention of researchers . Perovskite materials have high light absorption coefficient (~105), wide light absorption spectrum (200~1000nm), adjustable band gap (1.5~2.2eV), long carrier diffusion length (100~1000nm), These materials have many advantages, such as high mobility (12.5-66 cm ² /V·s) and low exciton binding energy (50-76 meV); in addition, these materials also have the advantages of simple preparation process and relatively low price. These advantages determine that it can be widely used in solar cells, light-emitting diodes, photodetectors, lasers and other fields. The perovskite material has the characteristics of wide emission spectrum and tunable light color, which determines that it has gradually become the most popular in the field of OLED. One of the potential luminescent materials.

In 2014, Tan et al. fabricated a FTO/TiO ₂ /CH ₃ NH ₃ PbI _3-x Cl _x /F8/Au type perovskite device by a low-temperature solution method, which not only overcomes the problems of liquid nitrogen and high pressure, but also obtains Next, the researchers optimized the structure of the perovskite LED device by using different electron or hole transport layers, which increased the external quantum efficiency (EQE) of the device to 0.5 Then the researchers regulated the perovskite light-emitting layer and reported a series of LED devices based on nano-perovskite materials. Zhang et al. prepared perovskite quantum dots by ligand-assisted redeposition method. Realized photoluminescence in the visible light range of 405-730 nm, and proved that small-sized perovskite quantum dots have high fluorescence quantum efficiency; recently, Wang Jianpu et al. The quantum well structure of the luminous efficiency of the device was introduced into the perovskite LED, and a perovskite light-emitting material with a multi-quantum well structure was developed. Using this dimension-tunable multi-quantum well perovskite material, the OLED device external quantum The efficiency reaches more than 12%. In addition, by adjusting the composition (including organic groups, halogen atom ratio, etc.) and morphology (different temperature, solvent treatment) of perovskite, materials with different band gaps can be obtained, so as to realize the perovskite material from Polychromatic emission in the near-infrared to visible range.

In the prior art, the perovskite light-emitting layer is prepared by spin-coating perovskite quantum dot dispersion, but direct spin-coating of high-concentration perovskite dispersion is prone to the agglomeration of quantum dots during the film formation process, which affects its performance. For optoelectronic properties, in order to avoid agglomeration, it is usually necessary to perform a relatively complex chemical treatment process on the quantum dots, and the operation is cumbersome.

Therefore, it is desirable to provide a method for preparing a perovskite light-emitting layer that can solve at least one of the above problems.

In view of this, the present invention is proposed.

SUMMARY OF THE INVENTION

One of the objectives of the present invention is to provide a method for preparing a perovskite light-emitting layer, mainly by spin-coating 2-5 layers of low-concentration (1-3)× ^10-6 M CsPbX ₃ perovskite quantum dot dispersion liquid, Low concentration can effectively avoid the agglomeration of quantum dots, and spin-coating multi-layer (2-5 layers) perovskite can improve the carrier recombination concentration in the light-emitting layer, thereby improving the photoelectric conversion performance of perovskite devices.

Another object of the present invention is to provide an application of the above-mentioned preparation method of a perovskite light-emitting layer in the preparation of a perovskite light-emitting device.

The third object of the present invention is to provide a perovskite light-emitting device, including the perovskite light-emitting layer prepared by the above-mentioned preparation method of the perovskite light-emitting layer, which has the same advantages as the above-mentioned perovskite light-emitting layer. The light-emitting device has good photoelectric conversion performance.

The fourth purpose of the present invention is to provide a preparation method of the above-mentioned perovskite light-emitting device, which is easy to operate.

In order to realize the above-mentioned purpose of the present invention, the following technical solutions are specially adopted:

In a first aspect, a method for preparing a perovskite light-emitting layer is provided, comprising the following steps:

2-5 layers of CsPbX ₃ perovskite quantum dot dispersion liquid with a concentration of (1-3)×10 ^-6 mol/L were spin-coated to obtain a perovskite light-emitting layer.

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

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

Preferably, on the basis of the technical solution of the present invention, X in CsPbX ₃ is any one or a combination of any two of I, Cl or Br;

Preferably, the solvent used in the CsPbX ₃ perovskite quantum dot dispersion liquid is n-octane or tetrahydrofuran.

In a second aspect, an application of the above method for preparing a perovskite light-emitting layer in preparing a perovskite light-emitting device is provided.

In a third aspect, a perovskite light-emitting device is provided, including the perovskite light-emitting layer prepared by the above-mentioned preparation method of the perovskite light-emitting layer.

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

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

Preferably, the substrate is an ITO substrate;

Preferably, the hole transport material of the hole transport layer includes polyparaphenylene vinylenes, polythiophenes, polysilanes, triphenylmethanes, triarylamines, hydrazones, pyrazolines, and azoles , one or a combination of at least two of carbazoles or butadienes, preferably polyethylenedioxythiophene-poly(styrene sulfonate);

Preferably, the electron transport material of the electron transport layer comprises 1,3,5-tris(1-phenyl-1H-benzimidazol-2-yl)benzene, 4,7-diphenyl-1,10- One or a combination of at least two of 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 preparing a perovskite light-emitting device is provided, wherein the light-emitting device is a light-emitting diode, and the preparation method for a perovskite light-emitting diode includes the following steps:

The hole transport layer, the perovskite light-emitting layer, the electron transport layer and the electrode material are sequentially prepared on the substrate to obtain a perovskite light-emitting diode.

Preferably, on the basis of the technical solution of the present invention, the preparation method of the above-mentioned 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 heat treatment to obtain a hole transport layer;

(c) spin-coating 2-5 layers of CsPbX ₃ perovskite quantum dot dispersion with a concentration of (1-3)×10 ^-6 mol/L on the hole transport layer obtained in step (b) to obtain perovskite light-emitting layer;

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

Preferably, on the basis of the technical solution of the present invention, the cleaning conditions in step (a) include: ultrasonic cleaning with water, ketones and alcohol solvents in sequence for 10-20 minutes, and plasma treatment for 5-10 minutes after drying;

Preferably, in step (b), the spin coating thickness is 30-60 nm, further preferably, the spin coating speed is 2000-4000 rpm, and the spin coating time is 30-50 s; preferably, the heat treatment temperature is 100-140° C., and the annealing time is 10-30min;

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

Preferably, the method of depositing the electron transport layer and depositing the electrode material in step (d) independently adopts thermal evaporation method or magnetron sputtering method, further preferably thermal evaporation method;

蒸镀厚度为30-50nm；Preferably, the evaporation rate of the electron transport layer is

The evaporation thickness is 30-50nm;

蒸镀厚度为1-100nm。Preferably, the evaporation rate of the electrode material is

The evaporation thickness is 1-100nm.

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

(1) The preparation method of the perovskite light-emitting layer provided by the present invention mainly involves spin coating 2-5 layers of low-concentration (1-3)× ^10-6 M CsPbX ₃ (X represents I, Cl or Br, etc.) perovskite Mineral quantum dot dispersion, low concentration can effectively avoid the agglomeration of quantum dots, spin-coating multi-layer (2-5 layers) perovskite can increase the carrier recombination concentration in the light-emitting layer, thereby improving the photoelectricity of perovskite devices. conversion performance.

(2) The method of the present invention is very simple to operate, and at the same time has good repeatability, which avoids the complicated process of chemically treating quantum dots. Improve the photoelectric conversion performance of perovskite devices.

(3) The multi-layer low-concentration perovskite quantum dot LED made of the perovskite light-emitting layer prepared by the preparation method of the perovskite light-emitting layer of the present invention is found through the photoelectric conversion performance test results. The quantum conversion efficiency increases first and then decreases with the increase of the number of light-emitting layers. When the number of spin layers is 4, the performance of the device is optimal, and the maximum conversion efficiency can reach more than 1.5%. Compared with single-layer perovskite Mine quantum dot LED, the performance is increased by 3 times.

Description of drawings

1 is a schematic structural diagram of a perovskite LED device according to an embodiment of the present invention;

FIG. 2 is the external quantum efficiency curve of the perovskite LED device of Example 1, wherein the photo is a photo of the luminescence when the device reaches the maximum brightness.

Detailed ways

The embodiments of the present invention will be described in detail below with reference to the examples, but those skilled in the art will understand that the following examples are only used to illustrate the present invention and should not be regarded as limiting the scope of the present invention. If the specific conditions are not indicated in the examples, it is carried out according to the conventional conditions or the conditions suggested by the manufacturer. The reagents or instruments used without the manufacturer's indication are conventional products that can be purchased from the market.

According to a first aspect of the present invention, a method for preparing a perovskite light-emitting layer is provided, comprising the following steps: spin-coating 2-5 layers of CsPbX ₃ calcium with a concentration of (1-3)×10 ^-6 mol/L Titanite quantum dot dispersion to obtain a perovskite light-emitting layer.

X in CsPbX ₃ perovskite quantum dots (Perovskite QDs) is typically but not limited to, for example, I, Cl or Br.

The CsPbX ₃ perovskite quantum dot dispersion liquid is obtained by dispersing the CsPbX ₃ perovskite quantum dots in a solvent, and the solvent includes but is not limited to n-octane or tetrahydrofuran.

The traditional spin-coating of perovskite quantum dot dispersion to obtain perovskite light-emitting layer is to directly spin-coat high-concentration (generally greater than 10 ^-6 M) perovskite dispersion, but it is easy to produce quantum dots during the film formation process. The phenomenon of agglomeration affects its optoelectronic properties. In order to avoid agglomeration, it is usually necessary to perform a relatively complex chemical treatment process on the quantum dots.

The present invention can effectively improve this problem by spin-coating 2-5 layers of CsPbX ₃ perovskite quantum dot dispersion liquid with a concentration of (1-3)×10 ^-6 mol/L.

The concentration of CsPbX ₃ perovskite quantum dot dispersion liquid is (1-3)×10 ^-6 mol/L, such as 1×10 ^-6 mol/L, 2×10 ^-6 mol/L or 3×10 ^-6 mol/L mol/L, the number of spin coats is 2-5 layers, such as 2 layers, 3 layers, 4 layers or 5 layers.

The agglomeration of quantum dots can be effectively avoided by spin-coating low-concentration (1-3)× ^10-6 M CsPbX3 _perovskite quantum dot dispersions, and by spin-coating multilayer (2-5 layers) perovskite quantum dots The dispersion liquid can increase the carrier recombination concentration in the light-emitting layer, and the preparation of the perovskite light-emitting layer by the method of the present invention can effectively improve the photoelectric conversion performance of the perovskite device. In addition, this method avoids the complicated process of chemically treating quantum dots, and the photoelectric conversion performance of perovskite devices can be effectively improved only by spin-coating low-concentration perovskite quantum dot light-emitting layers multiple times. The method is very simple, At the same time, the repeatability is good.

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

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

The conditions of spin coating are not limited, and conventional spin coating methods can be used; preferably, the spin coating speed of each layer of spin coating is independently 2000-4000 rpm; the spin coating time of each layer is independently 30 rpm. -50s.

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

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

According to a second aspect of the present invention, an application of the above-mentioned preparation method of a perovskite light-emitting layer in preparing a perovskite light-emitting device is provided.

Typical but non-limiting light emitting devices are, for example, polar ray tubes (CRTs), vacuum fluorescent tubes (VFDs), glow discharge tubes (GDDs), liquid crystal displays (LCDs), plasma displays (PDPs), light emitting diodes (LEDs), Field Emission Display (FED), Electroluminescent Display (ECD), Electrochromic Display (ECD), Laser Display (LPD), Electrophoretic Display (EPD), Ferroceramic Display (PLZT), etc., preferably applied to perovskite in LED devices.

Since the above method can effectively prevent the agglomeration of quantum dots, and the obtained perovskite light-emitting layer has good light-emitting performance, the photoelectric conversion performance of the perovskite device can be significantly improved when applied to the preparation of perovskite light-emitting devices.

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

The perovskite light-emitting device has the same advantages as the above-mentioned perovskite light-emitting layer, and the perovskite light-emitting device has good photoelectric conversion performance.

Typical but non-limiting light emitting devices are, for example, CRT, VFD, GDD, LCD, PDP, LED, FED, ECD, ECD, LPD, EPD or PLZT and the like.

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

Preferably, a typical perovskite light-emitting diode includes a substrate, a hole transport layer sequentially deposited on the surface of the substrate, the above-mentioned perovskite light-emitting layer, an electron transport layer and electrode materials.

A typical but non-limiting substrate is, for example, an ITO substrate.

The hole transport layer is a layered structure composed of hole transport materials. The hole transport material is a type of carrier that can be oriented and ordered under the action of an electric field when carriers (electrons or holes) are injected. The controllable migration of semiconductor materials to achieve charge transport. Typical but non-limiting hole transport materials are, for example, polyparaphenylenes, polythiophenes, polysilanes, triphenylmethanes, triarylamines, hydrazones, pyrazolines, azoles, carbazoles or butadiene, preferably polyethylenedioxythiophene-poly(styrenesulfonate) (abbreviated as PEDOT:PSS).

Here, "the above-mentioned perovskite light-emitting layer" refers to the perovskite light-emitting layer obtained by the method for preparing the perovskite light-emitting layer of the first aspect of the present invention, which is the same as the above description.

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

The electrode material is not limited, and conventional electrode materials in the art can be used, and a typical but non-limiting example is any one of LiF/Al or Ag.

The perovskite light-emitting diode with the typical structure has good photoelectric conversion performance, and the photoelectric conversion performance is better than that of the traditional high-concentration perovskite quantum dot dispersion liquid spin coating to prepare the light-emitting layer.

According to a fourth aspect of the present invention, a method for preparing a perovskite light-emitting diode with the above structure is provided, comprising the following steps:

The hole transport layer, the perovskite light-emitting layer, the electron transport layer and the electrode material are sequentially prepared on the substrate to obtain a perovskite light-emitting diode.

Preferably, the preparation method of the perovskite light-emitting diode with the above structure includes the following steps:

(a) cleaning the substrate;

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

(c) spin-coating 2-5 layers of CsPbX ₃ perovskite quantum dot dispersion with a concentration of (1-3)×10 ^-6 mol/L on the hole transport layer obtained in step (b) to obtain perovskite light-emitting layer;

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

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

Preferably, the cleaning conditions in step (a) include: ultrasonic cleaning with water, ketones and alcohol solvents in sequence for 10-20 minutes, and plasma treatment for 5-10 minutes after drying.

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

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

Drying is preferably carried out with nitrogen, and the plasma treatment time is, for example, 5 min, 8 min or 10 min.

Preferably, the spin coating thickness in step (b) is 30-60 nm, such as 30 nm, 40 nm, 50 nm or 60 nm.

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

Preferably, the heat treatment temperature is 100-140°C, such as 100°C, 110°C, 120°C, 130°C or 140°C; the annealing time is 10-30min, such as 10min, 20min or 30min.

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

Preferably, the method of depositing the electron transport layer and depositing the electrode material in step (d) independently adopts thermal evaporation method or magnetron sputtering method, further preferably thermal evaporation method;

例如

或

蒸镀厚度为30-50nm，例如30nm、40nm或50nm。Preferably, the evaporation rate of the electron transport layer is

E.g

or

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

例如

或

蒸镀厚度为1-100nm，例如1nm、2nm、5nm、10nm、20nm、30nm、50nm或100nm。Preferably, the evaporation rate of the electrode material is

E.g

or

The vapor deposition thickness is 1-100 nm, eg, 1 nm, 2 nm, 5 nm, 10 nm, 20 nm, 30 nm, 50 nm or 100 nm.

In a preferred embodiment, a typical preparation method of a perovskite light-emitting diode with the above-mentioned structure includes the following steps:

(a) ITO substrate cleaning: the ITO substrates were ultrasonically cleaned in deionized water, acetone and isopropanol for 10-20min respectively, and finally dried with nitrogen and treated with Plasma for 5-10min;

(b) Preparation of hole transport layer: filter the hole transport layer solution through a water filter, spin-coat at 2000-4000rpm for 30-50s, then anneal at 100-140℃ for 10-30min, and finally transfer into a nitrogen atmosphere glove box;

(c) Preparation of perovskite luminescent layer: firstly disperse CsPbX3 _perovskite quantum dots in tetrahydrofuran solution, then let the dispersion stand for more than 24 hours, take the supernatant and spin-coat to form a film, the concentration of the supernatant is (1 -3)×10 ^-6 mol/L, spin-coating 2-5 layers, obtained by superimposing one by one spin-coating layer by layer. The conditions for each layer of spin-coating are the same, that is, the spin-coating speed is 2000-4000rpm, and the spin-coating time is 30-50s ;

(d) depositing an electron transport layer on the perovskite light-emitting layer obtained in step (c) by vacuum evaporation, and then depositing an electrode material to obtain a perovskite light-emitting diode.

The present invention is further described below through specific examples and comparative examples, however, it should be understood that these examples are only used for more detailed description, and should not be construed to limit the present invention in any form. Each raw material involved in the present invention can be obtained commercially.

Example 1

A preparation method of a perovskite light-emitting diode, comprising the following steps:

(1) ITO substrate cleaning: the ITO substrate was ultrasonically cleaned in deionized water, acetone and isopropanol for 15 minutes, and finally dried with nitrogen and treated with Plasma for 8 minutes;

(2) Preparation of hole transport layer: The PEDOT:PSS solution was filtered through a 0.22 μm water filter, spin-coated at 3000 rpm for 40 s, then annealed at 130 °C for 20 min, and finally transferred to a nitrogen atmosphere glove box;

(3) Preparation of perovskite light-emitting layer: first disperse CsPbBr3 _perovskite quantum dots in tetrahydrofuran solution, let the dispersion stand for more than 24 hours, and take the supernatant (the quantum dot concentration of the supernatant is 1×10 ^{− 6} M) spin-coating film, the number of spin-coating layers is 4 layers, obtained by superimposing one layer of spin-coating, and the conditions of each layer of spin-coating are the same, that is, the spin-coating speed is 3000rpm and the spin-coating time is 40s;

蒸镀厚度为30nm；(4) Preparation of electron transport layer: The TPBI layer was deposited by vacuum evaporation, and the evaporation rate was

The evaporation thickness is 30nm;

蒸镀厚度为1nm，Al的蒸镀速率为

蒸镀厚度为100nm，得到的钙钛矿发光二极管结构如图1所示。(5) Electrode preparation: LiF and Al electrodes were deposited by vacuum evaporation, and the evaporation rate of LiF was

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

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

Example 2

A preparation method of a perovskite light-emitting diode, comprising the following steps:

(1) ITO substrate cleaning: the ITO substrate was ultrasonically cleaned in deionized water, acetone and isopropanol for 10 minutes respectively, and finally dried with nitrogen and treated with Plasma for 10 minutes;

(2) Preparation of hole transport layer: The PEDOT:PSS solution was filtered through a 0.22 μm water filter, spin-coated at 4000 rpm for 30 s, then annealed at 100 °C for 30 min, and finally transferred to a nitrogen atmosphere glove box;

(3) Preparation of perovskite light-emitting layer: first disperse CsPbI3 _perovskite quantum dots in tetrahydrofuran solution, let the dispersion stand for more than 24 hours, take the supernatant (the concentration of quantum dots in the supernatant is 1×10 ^{− 6} M) spin-coating film, the number of spin-coating layers is 4, which is obtained by superimposing one layer of spin-coating, and the conditions of each layer of spin-coating are the same, that is, the spin-coating speed is 4000rpm and the spin-coating time is 30s;

蒸镀厚度为50nm；(4) Preparation of electron transport layer: The TPBI layer was deposited by vacuum evaporation, and the evaporation rate was

The evaporation thickness is 50nm;

蒸镀厚度为2nm，Al的蒸镀速率为

蒸镀厚度为75nm。(5) Electrode preparation: LiF and Al electrodes were deposited by vacuum evaporation, and the evaporation rate of LiF was

The evaporation thickness is 2 nm, and the Al evaporation rate is

The vapor deposition thickness was 75 nm.

Example 3

A preparation method of a perovskite light-emitting diode, comprising the following steps:

(1) ITO substrate cleaning: the ITO substrate was ultrasonically cleaned in deionized water, acetone and isopropanol for 20 minutes, and finally dried with nitrogen and treated with Plasma for 5 minutes;

(2) Preparation of hole transport layer: PEDOT:PSS solution was filtered through a 0.22 μm water filter, spin-coated at 2000 rpm for 50 s, then annealed at 140 °C for 15 min, and finally transferred to a nitrogen atmosphere glove box;

(3) Preparation of perovskite light-emitting layer: first disperse CsPbCl ₃ perovskite quantum dots in tetrahydrofuran solution, let the dispersion stand for more than 24 hours, and take the supernatant (the concentration of supernatant quantum dots is 1×10 ^{− 6} M) spin-coating film, the number of spin-coating layers is 4, which is obtained by superimposing one layer of spin-coating, and the conditions of each layer of spin-coating are the same, that is, the spin-coating speed is 2000rpm and the spin-coating time is 50s;

蒸镀厚度为40nm；(4) Preparation of electron transport layer: The TPBI layer was deposited by vacuum evaporation, and the evaporation rate was

The evaporation thickness is 40nm;

蒸镀厚度为3nm，Al的蒸镀速率为

蒸镀厚度为50nm。(5) Electrode preparation: LiF and Al electrodes were deposited by vacuum evaporation, and the evaporation rate of LiF was

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

The vapor deposition thickness was 50 nm.

Example 4

The difference between this example and Example 1 is that the number of spin coats in step (3) is replaced with 2 layers, and other conditions are kept the same, to prepare a perovskite light-emitting diode.

Example 5

The difference between this example and Example 1 is that the number of spin coats in step (3) is replaced with 3 layers, and other conditions are kept the same, to obtain a perovskite light-emitting diode.

Example 6

The difference between this example and Example 1 is that the number of spin coats in step (3) is replaced with 5 layers, and other conditions are kept the same to obtain a perovskite light-emitting diode.

Example 7

The difference between this example and Example 1 is that CsPbBr ₃ in step (3) is replaced with CsPbCl _x Br _3-x (the value of x ranges from 0 to 3), and other conditions are kept the same to prepare perovskite led.

Example 8

The difference between this example and Example 1 is that CsPbBr ₃ in step (3) is replaced with CsPbI _x Br _3-x (the value of x ranges from 0 to 3), and other conditions remain the same to prepare perovskite led.

Example 9

The difference between this example and Example 1 is that the TPBI in step (4) is replaced with Bphen, and other conditions are kept the same, so as to obtain a perovskite light-emitting diode.

Example 10

The difference between this example and Example 1 is that the TPBI in step (4) is replaced with ZnO, and other conditions are kept the same to obtain a perovskite light-emitting diode.

Comparative Example 1

The difference between this example and Example 1 is that the number of spin coats in step (3) is replaced with one layer, and other conditions are kept the same to obtain a perovskite light-emitting diode.

Comparative Example 2

The difference between this example and Example 1 is that step (3) is replaced by dispersing CsPbBr ₃ perovskite quantum dots in a tetrahydrofuran solution, the concentration of the dispersion liquid is 1.27×10 ^-4 M, spin coating to form a film, spin coating The rotation speed was 3000 rpm, the spin coating time was 40 s, and other conditions were kept the same, and the perovskite light-emitting diode was prepared.

Test example

In order to investigate the effect of the perovskite light-emitting diodes obtained in the examples and comparative examples, the following experiments were carried out:

The photoelectric conversion performance (electroluminescence spectrum EL, current-voltage curve, external quantum efficiency EQE) of the perovskite OLED was tested using an integrating sphere test system. The luminescence spectrum integration time is 8ms.

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 External Quantum 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 the external quantum efficiency curve of the perovskite LED device of Example 1, and the highest external quantum efficiency is 1.5%.

It can be seen from the results in Table 1 and Figure 2 that the multi-layer CsPbBr3 perovskite quantum dots are obtained by dispersing and standing a low concentration of _{CsPbBr3 perovskite} quantum dot dispersion liquid, and then spin coating by layer-by-layer method light-emitting layer, and compared with the single-layer CsPbBr ₃ quantum dot device (comparative example 1), the photoelectric conversion performance test results found that the external quantum conversion efficiency of the CsPbBr ₃ perovskite quantum dot LED device increased with the number of light-emitting layers. It shows a trend of increasing first and then decreasing. When the number of spin coatings is 4 layers, the performance of the device is the best, and the maximum conversion efficiency can reach more than 1.5%. Compared with the device with a single layer in Comparative Example 1, the performance is improved by 3 times. . With the increase of the number of layers (1-4 layers), the highest external quantum efficiency of CsPbBr3 _perovskite -based LED devices can be improved from the initial 0.5% to 1.5%.

Examples 7 and 8 change the type of quantum dots, and the photoelectric conversion performance of the devices is not much different. Examples 9 and 10 change the type of electron transport layer material, which does not significantly affect the photoelectric conversion performance of the device.

Compared with Example 1, Comparative Example 2 was spin-coated with a high-concentration dispersion under the same conditions. The conversion performance is better due to the avoidance of excessive agglomeration, and the method avoids the complex chemical treatment of quantum dots, and the calcium can be effectively increased by only multiple spin-coating of low-concentration perovskite quantum dot light-emitting layers. Photoelectric conversion properties of titanite devices.

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

While specific embodiments of the present invention have been illustrated and described, it should be understood that various other changes and modifications can be made without departing from the spirit and scope of the invention. Therefore, it is intended that all such changes and modifications as fall within the scope of this invention be included in the appended claims.

Claims (23)

1. a preparation method of perovskite light-emitting layer, is characterized in that, comprises the following steps: Spin-coating 3-5 layers of CsPbX ₃ perovskite quantum dot dispersion with a concentration of (1-2)×10 ^-6 mol/L to obtain a perovskite luminescent layer; X in CsPbX ₃ is among I, Cl or Br any one or a combination of any two; The spin-coating speed of each layer is independently 2000-4000rpm; the spin-coating time of each layer is independently 30-50s. 2. according to the preparation method of the perovskite light-emitting layer of claim 1, it is characterized in that, the concentration of described CsPbX ₃ perovskite quantum dot dispersion liquid is 1 × 10 ^-6 mol/L; 4th floor. 3. according to the preparation method of the described perovskite light-emitting layer of claim 1 or 2, it is characterized in that, the solvent that described _CsPbX Perovskite quantum dot dispersion liquid adopts is n-octane or tetrahydrofuran. 4. Application of the method for preparing a perovskite light-emitting layer according to any one of claims 1-3 in the preparation of a perovskite light-emitting device. 5. A perovskite light-emitting device, characterized in that it comprises a perovskite light-emitting layer prepared by the method for preparing a perovskite light-emitting layer according to any one of claims 1-3. 6. The perovskite light-emitting device according to claim 5, wherein the light-emitting device is a light-emitting diode. 7. The perovskite light-emitting device according to claim 5, wherein the perovskite light-emitting diode comprises a substrate, a hole transport layer deposited on the surface of the substrate in turn, the perovskite light-emitting layer, and an electron transport layer. layers and electrode materials. 8. The perovskite light-emitting device according to claim 7, wherein the substrate is an ITO substrate. 9 . The perovskite light-emitting device according to claim 7 , wherein the hole transport material of the hole transport layer comprises polyparaphenylene vinylene, polythiophene, polysilane, and triphenylmethane. 10 . , one or a combination of at least two of triarylamines, hydrazones, pyrazolines, azoles, carbazoles or butadienes. 10. The perovskite light-emitting device according to claim 7, wherein the electron transport material of the electron transport layer comprises 1,3,5-tris(1-phenyl-1H-benzimidazole-2- base) one or a combination of at least two of benzene, 4,7-diphenyl-1,10-phenanthroline or zinc oxide. 11. The perovskite light-emitting device according to claim 10, wherein the electron transport material of the electron transport layer is 1,3,5-tris(1-phenyl-1H-benzimidazole-2- base) 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 preparation method of the perovskite light-emitting device according to any one of claims 6-12, wherein the light-emitting device is a light-emitting diode, and the preparation method of the perovskite light-emitting diode comprises the following steps: The hole transport layer, the perovskite light-emitting layer, the electron transport layer and the electrode material are sequentially prepared on the substrate to obtain a perovskite light-emitting diode. 14. according to the preparation method of the described perovskite light-emitting device of claim 13, is characterized in that, comprises the following steps: (a) cleaning the substrate; (b) spin-coating a hole transport layer solution on the cleaned substrate, and heat treatment to obtain a hole transport layer; (c) spin-coating 3-5 layers of CsPbX ₃ perovskite quantum dot dispersion with a concentration of (1-3)×10 ^-6 mol/L on the hole transport layer obtained in step (b) to obtain perovskite light-emitting layer; (d) depositing an electron transport layer on the perovskite light-emitting layer obtained in step (c), and then depositing an electrode material to obtain a perovskite light-emitting diode. 15. The method for preparing a perovskite light-emitting device according to claim 14, wherein the cleaning conditions in step (a) include: ultrasonic cleaning with water, ketones and alcohol solvents for 10-20min in turn, and drying with plasma Body treatment for 5-10min. 16 . The method for preparing a perovskite light-emitting device according to claim 14 , wherein the spin coating thickness in step (b) is 30-60 nm. 17 . 17. The method for preparing a perovskite light-emitting device according to claim 16, wherein the spin coating speed is 2000-4000 rpm, and the spin coating time is 30-50 s. 18 . The method for preparing a perovskite light-emitting device according to claim 16 , wherein the heat treatment temperature is 100-140° C., and the annealing time is 10-30 min. 19 . 19. according to the preparation method of the described perovskite light-emitting device of claim 14, it is characterized in that, in step (c), the spin coating rotation speed of each layer of spin coating is all independently 2000-4000rpm; The times were all independently 30-50s. 20 . The method for preparing a perovskite light-emitting device according to claim 14 , wherein the method of depositing the electron transport layer and depositing the electrode material in step (d) independently adopts thermal evaporation method or magnetron sputtering method. 21 . 21 . The method for preparing a perovskite light-emitting device according to claim 20 , wherein, in step (d), the method of depositing the electron transport layer and depositing the electrode material independently adopts a thermal evaporation method. 22 . 22. according to the preparation method of the described perovskite light-emitting device of claim 21, it is characterized in that, the evaporation rate of electron transport layer is

The evaporation thickness is 30-50nm. 23. according to the preparation method of the described perovskite light-emitting device of claim 22, it is characterized in that, the evaporation rate of electrode material is

The evaporation thickness is 1-100nm.

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