CN110534653A - Perovskite thin film and its preparation method and application - Google Patents

Abstract

The invention discloses a kind of perovskite thin films and its preparation method and application.The preparation method of the perovskite thin film includes the first step for preparing the first perovskite thin film layer and the second step that the second perovskite thin film layer is prepared on the first perovskite thin film layer, wherein, the second step includes: at least so that perovskite precursor solution is formed the second perovskite thin film layer on the first perovskite thin film layer using solwution method.The present invention also provides the perovskite thin films in preparing the purposes in electrooptical device.The present invention can obtain the perovskite thin film of surface more smooth using the preparation method for depositing perovskite thin film twice, the raw material composition that perovskite thin film can also be formed twice by adjusting front and back simultaneously obtains the novel perovskite thin film with different component combines, has superior device performance based on the photoelectric device that perovskite thin film provided by the invention is formed.

Description

Perovskite thin film and its preparation method and application

technical field

The invention particularly relates to a perovskite thin film, a preparation method and application thereof, and belongs to the technical field of organic thin films.

Background technique

At present, the methods for preparing perovskite thin films mainly include a step-by-step deposition method (or a step-by-step method) and a one-step deposition method (or a one-step method). The step-by-step deposition method includes: first depositing lead halide on the substrate, and then depositing the organic ammonium salt onto the lead halide film by immersing the lead halide film in an organic ammonium salt solution, or using spin coating and other methods, and the lead halide and organic The ammonium ions react to form a perovskite precursor film, which is finally obtained by thermal annealing. The one-step deposition method includes: depositing a perovskite precursor solution mixed with lead halide and organic ammonium salt directly onto a substrate to form a perovskite precursor film, and finally obtaining a crystalline perovskite film by thermal annealing. For the one-step deposition method, usually in the process of spin-coating the mixed solution of lead halide and organic ammonium salt, an organic solvent that does not dissolve perovskite (hereinafter referred to as anti-solvent) is added dropwise to rapidly induce the formation of perovskite grains , forming the seed crystal required for perovskite crystal growth, thereby assisting the perovskite crystal growth in the subsequent thermal annealing process, and obtaining high-quality perovskite crystal thin films.

For the above-mentioned step-by-step preparation of perovskite films, the crystals are formed by the diffusion reaction of organic ammonium ions. Due to the influence of the diffusion process, the conversion of lead halide is usually incomplete, so the perovskite film containing lead halide is obtained, forming certain flaws. However, when the perovskite film is prepared by the one-step method, due to the fast drying speed of the film during the spin coating process, the seed crystal required to assist the growth of the perovskite crystal in the subsequent thermal annealing process cannot be formed in the perovskite precursor film, or it can only be A limited number of perovskite seeds are obtained. Therefore, the perovskite films prepared by this method usually have poor crystal uniformity and poor quality.

In addition, due to the large difference in the ionic radius of different monovalent cations and monovalent anions, when preparing perovskite films composed of composite ions, it is easy to cause ion segregation, resulting in no ideal perovskite crystal films. For example, when using Cs ⁺ and NH ₂ CHNH ₂ ⁺ to prepare composite perovskite thin films with wider and narrower band gaps, the ideal α-phase can not usually be obtained by the one-step method, but a yellow δ-phase is obtained. By combining the precursor solutions of different lead halides and organic amine salts in a step-by-step method, different compositions of perovskite thin film materials can be obtained by blending. However, such a preparation method is not efficient, and performance adjustment is not easy.

Since the performance of perovskite thin film optoelectronic devices is affected by the crystal quality of the perovskite thin film, the performance of perovskite thin film devices prepared by the above conventional methods is also affected to a certain extent.

SUMMARY OF THE INVENTION

The main purpose of the present invention is to provide a perovskite film and its preparation method and application to overcome the deficiencies of the prior art.

In order to realize the foregoing invention purpose, the technical scheme adopted in the present invention includes:

An embodiment of the present invention provides a method for preparing a perovskite thin film, including a first step of preparing a first perovskite thin film layer and a second step of preparing a second perovskite thin film layer on the first perovskite thin film layer step, wherein the second step includes: at least using a solution method to form a second perovskite thin film layer on the first perovskite thin film layer with a perovskite precursor solution.

In some embodiments, the first perovskite thin film layer and the second perovskite thin film layer are both perovskite polycrystalline thin films, and the perovskite precursor solution used in the second step can The first perovskite thin film layer is partially dissolved.

The embodiment of the present invention also provides the perovskite thin film prepared by the method.

The embodiments of the present invention also provide the use of the perovskite thin film in the preparation of optoelectronic devices.

Embodiments of the present invention also provide an optoelectronic device comprising the perovskite thin film.

Embodiments of the present invention also provide a device, which includes the perovskite thin film or the optoelectronic device.

Compared with the prior art, the advantages of the present invention include:

(1) During the preparation of the second solution deposition perovskite film, the perovskite precursor solution can partially dissolve the prefabricated perovskite film to obtain a large number of perovskite nanocrystals. The crystal becomes the seed crystal in the second perovskite thin film crystal growth process, so it has more crystallization sites, so that the final perovskite thin film has small and uniform crystal size, low film surface roughness, and reduced film defects;

(2) Perovskite thin films with different ion complexes can be obtained by using a perovskite thin film solution different from the prefabricated perovskite thin film solution for the second time; Perovskite nanocrystals provide the seeds needed for crystal growth for subsequent perovskite films. Therefore, this method can effectively promote perovskite films formed by different combinations of anions and cations. The chemical composition is adjusted to obtain perovskite films with different optoelectronic properties;

(3) Since the perovskite thin film provided by the present invention has higher density and surface uniformity, the optoelectronic device based on the perovskite thin film has more excellent device performance.

Description of drawings

Fig. 1 is a schematic diagram of the preparation process of a perovskite film in a typical implementation case of the present invention;

2 is a schematic structural diagram of a typical perovskite thin-film solar cell in an embodiment of the present invention;

3a-3d are the statistical data of four performance parameters (open circuit voltage, short circuit current, fill factor and conversion efficiency) of the solar cells prepared in Examples 1, 2, 3 and Comparative Examples 1, 2, and 3 of the present invention comparison chart;

Figure 4a and Figure 4b are the I-V characteristic curve and the EQE test curve of the solar cell in Example 1 and Comparative Example 1, respectively;

Figure 5a and Figure 5b are the I-V characteristic curve and the EQE test curve of the solar cell in Example 2 and Comparative Example 2, respectively;

Figure 6a, Figure 6b are the I-V characteristic curve and the EQE test curve of the solar cell in Example 3 and Comparative Example 3, respectively;

7a and 7b are AFM characterization diagrams of the perovskite thin films in Example 1 and Comparative Example 1, respectively;

7c and 7d are SEM images of the upper surfaces of the perovskite films in Example 1 and Comparative Example 1, respectively;

7e and 7f are SEM images of the cross-sections of the perovskite thin films in Example 1 and Comparative Example 1, respectively;

Figure 7g and Figure 7h are respectively the fluorescence intensity spectrum and the fluorescence lifetime spectrum of the perovskite thin film in Example 1 and Comparative Example 1;

8 is a perovskite crystal particle size distribution diagram of the perovskite thin films in Example 1 and Comparative Example 1;

9a-9d are the decay curves of the four performance parameters (open circuit voltage, short circuit current, fill factor and conversion efficiency) of the solar cells of Examples 1, 4, 5 and Comparative Example 1 with test time, respectively.

10 is the I-V characteristic curve of the solar cells of Example 6 and Comparative Example 1;

11 is the I-V characteristic curve of the solar cells of Example 7 and Comparative Example 1;

Description of reference numerals: 001-structural support material, 002-bottom electrode, 003-bottom electrode modification layer, 004-perovskite film, 005-top electrode interface modification layer, 006-top electrode.

Detailed ways

In view of the deficiencies in the prior art, the inventor of the present application was able to propose the technical solution of the present invention after long-term research and extensive practice. The technical solution, its implementation process and principle will be further explained as follows.

An embodiment of the present invention provides a method for preparing a perovskite thin film, including a first step of preparing a first perovskite thin film layer and a second step of preparing a second perovskite thin film layer on the first perovskite thin film layer step, wherein the second step includes: at least using a solution method to form a second perovskite thin film layer on the first perovskite thin film layer with a perovskite precursor solution.

Further, the first perovskite thin film layer and the second perovskite thin film layer are both perovskite polycrystalline thin films, and the perovskite precursor solution used in the second step can The perovskite thin film layer is partially dissolved.

Further, the solution method includes a coating method or a printing method.

Preferably, the coating method includes spin coating, blade coating, slit coating or spray coating, but is not limited thereto; the printing method includes gravure printing, flexographic printing or inkjet printing law, but not limited to this.

In some specific embodiments, the second step further includes: after the perovskite precursor solution is coated on the first perovskite thin film layer to form a coating layer, applying the perovskite precursor solution to the first perovskite thin film layer. The coating is applied with an antisolvent, forming a second perovskite thin film layer.

In some specific embodiments, the preparation method specifically includes: annealing the second perovskite thin film layer obtained in the second step, the annealing temperature is 80-150°C, and the annealing time is 45s-30min, to obtain the perovskite film.

Further, the solute components of the perovskite precursor solution include positive monovalent cations, positive divalent cations, negative monovalent halogen ions, and the like.

Specifically, the positive monovalent cation includes any one or a combination of two or more in cesium ion, methylammonium ion, imidium ion, etc., and the positive divalent cation includes any one or two in lead ion, tin ion, etc. In the above combination, the negative monovalent halide ion includes any one or a combination of two or more of chloride ion, bromide ion, and iodide ion, and is not limited to this.

Further, the solvent in the perovskite precursor solution includes any one or two or more of dimethyl sulfoxide (DMSO), γ-butyrolactone (GBL), and dimethylformamide (DMF). combination, but not limited to this.

Further, the concentration of the perovskite precursor solution is preferably 1-1.5 mol/L.

Further, the preparation method includes: using a chemical deposition method and/or a physical deposition method to prepare and form the first perovskite thin film layer.

Further, the materials of the first perovskite thin film layer and the second perovskite thin film layer are the same or different.

In some specific embodiments, the preparation method specifically includes: preparing and forming the first perovskite thin film layer on a substrate, and the substrate includes a flexible or rigid organic conductive substrate or an inorganic conductive substrate.

Preferably, the substrate includes a hole or electron transport type organic semiconductor thin film or an inorganic semiconductor thin film formed thereon.

Preferably, the material of the hole-transporting organic semiconductor thin film may include polyethylenedioxythiophene-poly(styrene sulfonate) (PEDOT: PSS) or poly[bis(4-phenyl)(2,4) , 6-trimethylphenyl)amine] (PTAA), but not limited thereto.

Preferably, the material of the hole-transporting inorganic semiconductor thin film may include nickel oxide, but is not limited thereto.

Preferably, the material of the electron transport inorganic semiconductor thin film may include titanium oxide or tin oxide, but is not limited thereto.

Preferably, the substrate may include ITO glass, FTO glass or plastic-based flexible conductive electrodes, but is not limited thereto.

The embodiment of the present invention also provides the perovskite thin film prepared by the method.

Further, the chemical formula of the perovskite film is ABX ₃ , wherein A is a positive monovalent cation, B is a positive divalent cation, and X is a negative monovalent halogen ion.

Preferably, A includes any one or a combination of two or more of cesium ion, methylammonium ion, and methylimidium ion, but is not limited thereto.

Preferably, B includes lead ions and/or tin ions, but is not limited thereto.

Preferably, X includes any one or a combination of two or more of chloride ion, bromide ion, and iodide ion, but is not limited thereto.

The embodiments of the present invention also provide the use of the perovskite thin film in the preparation of optoelectronic devices.

Embodiments of the present invention also provide an optoelectronic device comprising the perovskite thin film.

Preferably, the optoelectronic device includes a solar cell, a photoelectric sensor, an electroluminescent device or an X-ray sensor.

Embodiments of the present invention also provide a device, which includes the perovskite thin film or the optoelectronic device. Typical devices include photovoltaic devices, detection devices, display devices, and the like.

In order to make the objectives, technical solutions and advantages of the present invention clearer, the specific embodiments of the present invention will be described in detail below with reference to the accompanying drawings. Examples of these preferred embodiments are illustrated in the accompanying drawings. The embodiments of the invention shown in the drawings and described with reference to the drawings are merely exemplary and the invention is not limited to these embodiments.

Here, it should also be noted that, in order to avoid obscuring the present invention due to unnecessary details, only the structures and/or processing steps closely related to the solution according to the present invention are shown in the drawings, and the related structures and/or processing steps are omitted. Other details not relevant to the invention.

In some embodiments, a method for preparing a perovskite thin film may include two steps, namely: first, depositing a prefabricated underlying perovskite thin film (ie, the first perovskite thin film) on a substrate, Then, a second perovskite film (ie, the second perovskite film) is deposited on the prefabricated underlying perovskite film by the solution method. The specific preparation process of the perovskite film can be seen in Figure 1.

In some specific embodiments, during the second solution deposition to form the perovskite film, the perovskite precursor solution can partially dissolve the prefabricated underlying perovskite film to obtain a large number of perovskite nanocrystals . Compared with the conventional one-step film forming process, the preparation method provided by the present invention can generate a larger number of seeds and more crystallization sites, so that the crystal size of the finally formed perovskite film is fine and uniform, and the surface roughness of the film is reduced. low, film defects are reduced.

The perovskite film prepared in the embodiment of the present invention is a chemical material with a chemical structure of ABX ₃ , wherein A is a positive monovalent cation, which includes: cesium ion (Cs ⁺ ), methylammonium ion (CH ₃ NH ) ₃ ⁺ ), imidium ion (NH ₂ CHNH ₂ ⁺ ) or a mixed ion formed by the above three ions in any proportion; B is a positive divalent cation, which includes: lead ion (Pb ²⁺ ), tin ion (Sn ^{2 +} ) or a mixed ion formed by the above two ions in any proportion; X is a negative monovalent halide ion, such as: chloride ion (Cl ^- ), bromide ion (Br ^- ), iodide ion (I ^- ) or from the above Mixed ions formed by three ions in any proportion. Specifically, the following embodiment 1 provides a perovskite film mainly composed of methylamine ions, lead ions, iodide ions and chloride ions; the following embodiment 2 provides a perovskite film mainly composed of methylamine ions, lead ions, iodine ions Perovskite film composed of ions and bromide ions; Example 3 below provides a perovskite film mainly composed of methylamine ions, lead ions and iodine ions. The following Examples 13 and 14 respectively provide a perovskite film mainly composed of methylamine, methionine, lead ions, iodide ions and bromide ions; the following Examples 8, 10 and 12 provide respectively A perovskite thin film mainly composed of methylamine ion, methionine ion, cesium ion, lead ion, iodide ion and bromide ion was prepared.

It should be pointed out that, when the perovskite thin film is prepared by the twice perovskite film forming method provided in the embodiment of the present invention, the first perovskite thin film forming (that is, the first perovskite thin film layer is formed) and the second perovskite thin film are formed. The materials used for the secondary perovskite film formation (that is, the preparation and formation of the second perovskite thin film layer) can be the same (for example, refer to the following Examples 1, 2, 3, 4, 5, 8, 11, 13, 14), can also be different (for example, refer to the following Examples 6, 7, 9).

The substrate described in the embodiments of the present invention may be a rigid or flexible conductive support material deposited on a hole or electron transport type organic or inorganic semiconductor thin film. The hole-transporting organic thin films include: PEDOT:PSS (for example, the following examples 1-7, and 9), PTAA (for example, the following example 8), and the hole-transporting inorganic semiconductor thin films include: nickel oxide (eg Example 13 below). Or some other hole-transporting materials known to those skilled in the art, such as polythiophene derivatives, P3CT-Na, etc., can also be used as the substrate for the subsequent two perovskite thin film deposition processes after being prepared into thin films. middle. The electron-transporting inorganic semiconductor thin films include titanium oxide (for example, Example 14 below), tin oxide (for example, Example 7 and Example 9 below), and the like. Or other electron-transporting materials known to those skilled in the art, such as zinc tin oxide, aluminum-doped zinc oxide, fullerene derivatives, etc., can also be used as a substrate for subsequent In two perovskite thin film deposition processes. The conductive support material can be rigid, such as ITO glass (for example, Examples 1-11 and 13 below), FTO glass (for example, Example 14 below), or plastic-based flexible conductive electrodes (for example, as follows). Example 12), or some other substrate materials, such as ceramics, non-woven fabrics, etc., after surface treatment, can also be prepared into conductive films for subsequent preparation of perovskite films.

In still other embodiments, the preparation method for forming a prefabricated underlying perovskite thin film by first deposition on the substrate (that is, the method for preparing and forming the first perovskite thin film layer on the substrate) comprises: using a one-step method or a step-by-step method. The perovskite polycrystalline thin film layer is prepared, or the pre-synthesized perovskite nanocrystals are deposited on the substrate by the solution method to form the perovskite thin film layer.

In a typical implementation case of the present invention, the preparation method may include: firstly preparing a perovskite thin film (ie, the first perovskite thin film layer) by a one-step method or a step-by-step method, and then preparing the perovskite thin film layer on the formed perovskite thin film layer. A perovskite thin film (ie, the second perovskite thin film layer) is formed by the second deposition. For example, the following comparative example 1, comparative example 2, and comparative example 3 are all prepared by one-step method, and examples 1-3 are all perovskite thin films prepared by the preparation method provided by the present invention.

In the preparation method of the perovskite film provided by the present invention, pre-synthesized perovskite quantum dot nanocrystals can also be used, and a layer of perovskite quantum dot nanocrystals film (that is, the first calcium titanium thin film layer), and then a second perovskite thin film (ie, the second perovskite thin film layer) is grown on this basis (please refer to Example 9 below). Since the synthesis method of perovskite quantum dot nanocrystals is relatively mature, the chemical composition of crystals and the quality of crystals are well controlled, the prepared perovskite quantum dot nanocrystal films are used to induce the crystal growth of subsequent perovskite films with Very good effect.

In a typical implementation case of the present invention, the second perovskite thin film layer needs to be prepared by a solution method. Specific preparation methods may include coating, printing methods and the like. The coating method includes: spin coating, blade coating, slit coating, spray coating and the like. The most practical methods include: spin coating (see Examples 1-8, 11, 12, 13, 14 below), blade coating (see Example 10 below), and spray coating (see Example 9 below); functions Printing preparation methods of films, such as gravure printing, flexographic printing, inkjet printing, etc.

High-quality perovskite films can be used to prepare perovskite thin-film photovoltaic cells, perovskite electroluminescent devices, perovskite photodetectors, and perovskite X-ray sensors. According to different device types, the specific structure of perovskite optoelectronic devices will be different. The perovskite thin films can be prepared by the methods provided in the embodiments of the present invention. The following Examples 1-14 respectively show the perovskite solar cells prepared by using the perovskite thin film provided by the present invention.

FIG. 2 is a schematic structural diagram of a typical solar cell device prepared in an embodiment of the present invention. Wherein, 001 is a structural support material, 002 is a bottom electrode, 003 is a bottom electrode modification layer, 004 is a perovskite film, 005 is a top electrode interface modification layer, and 006 is a top electrode. The structural support material 001 and the bottom electrode 002 are combined to form the rigid or flexible conductive support material; 003 is a hole- or electron-transporting organic or inorganic semiconductor thin film deposited thereon (the rigid or flexible conductive support material). The perovskite thin film layer 004 can be prepared by the preparation method of the perovskite thin film provided by the present invention.

The bottom electrode modification layer 003 is deposited on the rigid or flexible conductive support material by a method known to those skilled in the art, and no specific preparation method is described in the specification of the present invention. The preparation process of the perovskite thin film in the embodiment of the present invention can be referred to as shown in FIG. 1 .

Comparative Example 1

One-step preparation of MAPbI _3-x Cl _x thin films and their perovskite solar cells based on glass/ITO/PEDOT:PSS substrates;

Step 1: Methionine, PbCl ₂ and PbI ₂ were dissolved in 1 ml of a mixed solvent of γ-butyrolactone (GBL) and dimethyl sulfoxide (DMSO) at a weight ratio of 206.7 mg: 19.5 mg: 613.4 mg (7:3, v/v), configured to obtain a mixed solution of perovskite precursors with a concentration of 40%;

Step 2: Take 50 μl of the above perovskite precursor mixed solution and drop it on the substrate with the structure: glass/ITO/PEDOT:PSS (for the preparation method, please refer to the literature [1] Huang J, Wang K, Chang J, et al. Improving the Efficiency and Stability of Inverted Perovskite Solar Cells with Dopamine-Copolymerized PEDOT: PSS as Hole Extraction Layer[J]. Journal of MaterialsChemistry A, 2017, 5(26).), starting the spin coating with a continuous two-step spin coating procedure, The first spin coating program set the speed to 1000rpm and lasted 10s, the second step spin coating program set the speed to 4000rpm and the duration was 30s. At the 17s after entering the second step spin coating program, add 450μl toluene dropwise, spin coating After the end, the perovskite film was obtained by annealing on a hot plate at 100 °C for 10 min;

Step 3: spin-coating an electron transport layer on the basis of Step 2, wherein the electron transport layer used is PC ₆₁ BM. Specifically, using anhydrous chlorobenzene as a solvent, configuring a PC ₆₁ BM chlorobenzene solution with a concentration of 20 mg/mL, dripping the solution on the above-mentioned perovskite film 004, and spin-coating at a speed of 1000 rpm to obtain an electron transport layer;

Step 4: On the basis of Step 3, vacuum coating is performed to prepare a metal electrode layer. The electrode layer is metal aluminum; specifically, under a high vacuum condition of 10 ^-5 Pa, a metal aluminum layer of about 100 nm is deposited by thermal evaporation coating to complete the preparation of the device.

Example 1

The MAPbI _3-x Cl _x thin film and its perovskite solar cell were prepared by two deposition perovskite films on glass/ITO/PEDOT:PSS substrate. The structure of the cell can be seen in Figure 2;

Step 1: Refer to step 1 in the method of Comparative Example 1 to configure the perovskite precursor mixed solution;

Step 2: Referring to the spin coating deposition method of the perovskite precursor film in step 2 in the method of Comparative Example 1, change the thermal annealing time to 20s, and complete the pre-deposition of a perovskite film on the substrate;

Step 3: On the basis of the perovskite film prepared in the aforementioned step 2, drop the perovskite precursor solution again, and immediately start the continuous two-step spin coating procedure to deposit the perovskite film for the second time. Specifically, the spin coating program sets the spin coating speed to 1000 rpm for 10 s; then starts to accelerate, and enters the second stage of spin coating with a rotating speed of 4000 rpm and a duration of 30 s. 450 μl of toluene was added dropwise as an anti-solvent, and after spin coating, annealed on a hot plate at 100 °C for 10 min to obtain perovskite film 004;

Step 4: Complete the preparation of the electron transport layer PC ₆₁ BM005 by referring to Step 3 in the method of Comparative Example 1;

Step 5: Refer to step 4 in the method of Comparative Example 1 to complete the vacuum coating preparation of the metal aluminum electrode 006.

Comparative Example 2

One-step preparation of MAPbI _3-x Br _x thin films and their perovskite solar cells on glass/ITO/PEDOT:PSS substrates;

Step 1: Methionine, PbBr ₂ and PbI ₂ were dissolved in 1 ml of a mixed solvent of γ-butyrolactone (GBL) and dimethyl sulfoxide (DMSO) at a weight ratio of 206.7 mg: 77.0 mg: 548.6 mg (7:3, v/v), configured to obtain a mixed solution of perovskite precursors with a concentration of 40%;

Using the perovskite precursor solution configured in step 1, referring to steps 2, 3, and 4 of comparative example 1, the perovskite thin film and the corresponding solar cell device are completed.

Example 2

MAPbI _3-x Br _x thin film and its perovskite solar cell were prepared by two deposition perovskite films on glass/ITO/PEDOT:PSS substrate. The structure of the cell can be seen in Figure 2;

Step 1: Refer to Step 1 of Comparative Example 2 to configure the perovskite precursor solution;

Using the perovskite precursor solution configured in step 1, referring to steps 2, 3, 4, and 5 of Example 1, the perovskite thin film and the corresponding solar cell device are completed.

Comparative Example 3

One-step preparation of _MAPbI3 thin films and their perovskite solar cells on glass/ITO/PEDOT:PSS substrates;

Step 1: Methionine and PbI were dissolved in 1 ml of a mixed solvent of γ-butyrolactone (GBL) and dimethyl sulfoxide (DMSO) at a weight ratio of 206.7 mg: 645.4 _mg (7:3, v /v), configure to obtain a mixed solution of perovskite precursors with a concentration of 40%;

Using the perovskite precursor solution configured in step 1, referring to steps 2, 3, and 4 of comparative example 1, the perovskite thin film and the corresponding solar cell device are completed.

Example 3

The MAPbI ₃ film and its perovskite solar cell were prepared by two deposition of perovskite film on glass/ITO/PEDOT:PSS substrate. The structure of the cell can be seen in Figure 2;

Step 1: Referring to Step 1 of Comparative Example 3, configure the perovskite precursor solution.

Using the perovskite precursor solution configured in step 1, referring to steps 2, 3, 4, and 5 of Example 1, the perovskite thin film and the corresponding solar cell device are completed.

The performance analysis comparison of embodiment 1-3 and comparative example 1-3 is shown in table 1:

Table 1 is the highest value of PCE and the average value of performance parameters of Examples 1, 2, 3 and Comparative Examples 1, 2, 3

From Table 1 and Fig. 3a-Fig. 3d, Fig. 4a-Fig. 4b, Fig. 5a-Fig. 5b, Fig. 6a-Fig. 6b, it can be seen that when compared with the control group with the same perovskite composition, the result obtained by the present invention The solar cells of the example groups all have slightly lower Voc, higher Jsc and FF, and higher PCE. The highest efficiency of the perovskite cell composed of CH ₃ NH ₃ PbI _3-x Cl _x increased from 14.20% to 15.70%; the cell composed of CH ₃ NH ₃ PbI _3-x Br _x increased from 14.65% increased to 15.02%; the efficiency of the perovskite cell with CH ₃ NH ₃ PbI ₃ was increased from 13.93% to 14.98%.

Morphology analysis of perovskite thin films in Example 1 and Comparative Example 1:

Please refer to Fig. 7a-Fig. 7h and Fig. 8 for comparative analysis of the perovskite active layer films of Example 1 and Comparative Example 1. Fig. 7a, Fig. 7c, Fig. 7e are AFM, surface SEM and cross-section SEM of the perovskite light-absorbing layer 3 in Example 1, respectively; Fig. 7b, Fig. 7d, Fig. 7f are the perovskite light-absorbing layer 3 in Comparative Example 1, respectively. AFM, surface SEM and cross-section SEM; Figure 7g is the fluorescence intensity spectrum of the perovskite light-absorbing layer in Example 4 and Comparative Example 2, Figure 7h is the fluorescence lifetime spectrum of the two; Figure 8 is the particle size of the two Statistical distribution of diameters. It can be seen from Fig. 7a and Fig. 7b that the perovskite film of Comparative Example 1 (Fig. 7b) has more and larger pores and larger surface undulations. From the measurement results, Example 1 (Fig. 7a) The average surface roughness is 9.91 nm, while the average surface roughness in Comparative Example 1 (Figure 7b) is 13.10 nm, so it can be concluded that in the preparation process of the perovskite light-absorbing layer 3, the prefabricated perovskite film is added to assist The film formation can obtain a smoother and flatter perovskite film.

It can be seen from Fig. 7c and Fig. 7d that, compared with Comparative Example 1 (Fig. 7d), the crystal size distribution in Example 1 (Fig. 7c) is concentrated at 100-200 nm, and the inter-crystal gap is smaller and the combination is tighter , while in Comparative Example 1 (Figure 7d), the perovskite crystal size is mainly distributed in 200-300 nm, and there are obvious gaps between the crystals. Overall, the film quality of Example 1 (Figure 7c) is better. .

Combining Figure 7e and Figure 7f: In Comparative Example 1 (Figure 7f), the undulation of the cross-section is large, indicating that the surface has a large flatness, which is consistent with the conclusion obtained by AFM. At the same time, the film thickness of the two is basically the same, about is 270nm.

Combining Figure 7g and Figure 7h, it can be seen that the perovskite layer of Example 4 has a larger fluorescence intensity and a longer fluorescence lifetime, wherein the fluorescence lifetime in Example 4 is 85ns, while the fluorescence lifetime in Comparative Example 2 is 58ns. This indicates that there are fewer crystalline defects within the film that can serve as centers for carrier recombination.

Therefore, from the analysis and test results of Example 1 and Comparative Example 1, the perovskite solar light absorbing layer obtained by the invention has a smoother and flatter film surface, and its crystal size is smaller and the arrangement is more compact, so , which has fewer crystal defects, is more conducive to the transport of carriers, and improves the overall quality of the film.

Example 4

Change the process of prefabricated film, and prepare MAPbI _3-x Cl _x film and its perovskite solar cell based on glass/ITO/PEDOT: PSS substrate by one-step method. The structure of this cell can be seen in Figure 2;

The annealing time in step 2 of Example 1 was changed to 10s, and other conditions were kept the same as those in Example 1.

Example 5

The process of presetting the thin film was changed, and the MAPbI _3-x Cl _x thin film and its perovskite solar cell were prepared by one-step method based on glass/ITO/PEDOT:PSS substrate. The structure of the cell can be seen in Figure 2.

The annealing time in step 2 of Example 1 was changed to 45s, and other conditions were kept the same as those in Example 1.

The performance analysis and comparison of Examples 1, 4, 5 and Comparative Example 1 are shown in Table 2:

Table 2 shows the performance parameters of Examples 1, 4, 5 and Comparative Example 1

Numbering Short annealing time Voc(V) Jsc(mA/cm²) FF PCE((mW/cm²) Comparative Example 1 1.07 18.84 0.71 14.05 Example 4 10s 1.06 18.96 0.74 14.87 Example 1 20s 1.05 19.06 0.76 15.21 Example 5 45s 1.01 19.54 0.75 14.80

It can be seen from Table 1 and Figure 2 that the short annealing time in step (3) affects the performance of the solar cell device: in Comparative Example 1, step (3) is omitted, that is, there is no perovskite prefabricated film, For the directly prepared perovskite light-absorbing layer 3, in Examples 1-3, the short annealing times in step (3) are 10s, 20s, and 45s, respectively. As can be seen from Table 2, the solar cell without perovskite prefabricated film has higher open circuit voltage (Voc), but lower short-circuit current density (Jsc) and fill factor (FF), so its energy conversion efficiency (PCE ) is the lowest compared with several groups of Examples; it can be seen from Figures 9a-9d that the stability of Comparative Example 1 is also the lowest compared with the Examples.

In Examples 1-3, the process of prefabricating the perovskite film is added, and the performance and stability of the device formed based on this are improved to varying degrees, and change with the change of the short annealing time of the prefabricated film. When the short annealing time is 20s, the PCE of the battery device is the highest, and the stability of the battery device is also higher. Therefore, a short annealing time of 20 s is a more preferable condition.

Example 6

The composition of the pre-fabricated film was changed, and the MAPbI _3-x Cl _x film and its perovskite solar cell were prepared by one-step method based on glass/ITO/PEDOT:PSS substrate. The structure of the cell can be seen in Figure 2;

Steps: Referring to the methods in steps 1 and 2 of Example 2, a layer of perovskite pre-fabricated thin films with CH ₃ NH ₃ PbI _3-x Br _x was prepared on a glass/ITO/PEDOT:PSS substrate. The perovskite active layer thin film and the solar cell device were prepared by referring to the methods of steps 3, 4 and 5 in Example 1 again.

Example 7

The composition of the pre-fabricated film was changed, and the MAPbI _3-x Cl _x film and its perovskite solar cell were prepared by one-step method based on glass/ITO/PEDOT:PSS substrate. The structure of the cell can be seen in Figure 2.

Steps: Referring to the methods in Steps 1 and 2 of Example 3, a layer of perovskite pre-fabricated thin films of CH ₃ NH ₃ PbI ₃ were prepared on a glass/ITO/PEDOT:PSS substrate. The perovskite active layer thin film and the solar cell device were prepared by referring to the methods of steps 3, 4 and 5 in Example 1 again. The performance analysis comparison of embodiment 6,7 and comparative example 1 is as shown in table 3:

Table 3 is the performance parameters of Examples 6, 7 and Comparative Example 1

Combine Table 3, Figure 10 and Figure 11 to analyze Examples 6 and 7: In Examples 6 and 7, the groups of the pre-set perovskite thin films (the first perovskite thin films) are respectively CH ₃ NH ₃ PbI _3-x Br _x , CH ₃ NH ₃ PbI ₃ . Different from the composition (CH ₃ NH ₃ PbI _3-x Cl _x ) of the solution used in the preparation of the perovskite light-absorbing layer 004, it can be seen from the comparison with the JV curves of Comparative Example 1 (Figure 10, Figure 11) that Example 6 The PCE of the batteries in 7 and 7 has been improved.

Example 8

The method of secondary film formation is applied to the ternary blended perovskite material, and the structure is ITO/SnO ₂ /PVSK/Sprio-OMeTAD/Ag upright perovskite solar cell;

Step 1: Preparation of _SnO electron transport layer on ITO glass (Reference 2 Jiang Q, Chu Z, Wang P, et al. Planar-Structure Perovskite Solar Cells with Efficiency beyond 21% [J]. Advanced Materials, 2017, 29 (46 ));

Step ₂ : Dissolve FAI:MABr:CsI:PbI2:PbBr2 in a mixed solvent of DMF:DMSO (v/v, 4: ₁ ) in a molar ratio of 1:0.02:0.0075:1.1:0.22 at 50°C Dissolve for more than 1 hour to obtain a ternary blended perovskite solution for later use;

Step 3: Set the spin coating program to two steps, specifically, set the spin coating speed to 1000 rpm for 10 s in the spin coating program; then start to accelerate and enter the second stage of spin coating, the speed is 5000 rpm, and the duration is 23 s. At 13s after the two-step spin-coating procedure, 100 μl of chlorobenzene was added dropwise as an anti-solvent, and after spin-coating, annealed on a hot plate at 100°C for 20s to obtain a perovskite prefabricated film;

Step 4: Start the secondary film formation on the perovskite preset film, set the spin coating program to two steps, specifically, set the spin coating speed to 1000 rpm for 10 s in the spin coating program; then start to accelerate, and enter the second stage of spinning. Coating, the rotation speed is 5000rpm, and the duration is 23s. At the 13s after entering the second step of the spin coating procedure, 100 μl of chlorobenzene is added dropwise as an anti-solvent. A perovskite film is obtained;

Step 5: Preparation of Spiro-OMeTAD hole transport layer (Reference 2);

Step 6: transfer to a vacuum evaporation chamber, and evaporate Ag electrodes with a thickness of 100 nm at 10 ^-5 Pa.

The battery performance analysis in Example 8 is shown in Table 4:

Table 4 is the performance parameters of the battery obtained in Example 8

V_OC(V) J_SC(mA/cm²) FF PCE (%) 1.05 20.24 0.71 15.09

Example 9

Combining the secondary film formation technology with spraying, a prefabricated film was prepared with CsPbBr ₃ nanocrystals, and then the film was sprayed to form a film based on the CsPbBr 3 nanocrystal, and it was prepared into a structure of ITO/ZnO/MACsPbI _3-x Br _x /PTAA/Al. Perovskite cell devices.

Step 1: Preparation of glass/ITO/ZnO substrate (please refer to Reference 3 for preparation method, Jin HH, Lee M, Han HJ, et al.Highly efficient low temperature solution processible planar typeCH ₃ NH ₃ PbI ₃ perovskite flexible solar cells[J] . Journal of Materials Chemistry A, 2016, 4(5): 1572-1578.);

Step 2: The _CsPbBr3 nanocrystal cyclohexane dispersion liquid synthesized at room temperature (preparation method reference 4, SunS, Yuan D, Xu Y, et al. Ligand-Mediated Synthesis of Shape-Controlled Cesium LeadHalide Perovskite Nanocrystals via Reprecipitation Process at RoomTemperature[J].Acs Nano, 2016, 10(3): 3648.) Spin coating on the above-mentioned substrate at a speed of 2000rpm for 30s to prepare a _CsPbBr3 nanocrystalline thin film;

Step 3: Prepare a solution according to the method of Step 1 of Example 2, and spray the solution to form a perovskite film. By controlling the spraying parameters: the liquid feeding speed of the spraying process is 0.25 mL/min, the height of the spray head is 3 cm, and the temperature of the spraying substrate is 45 ° C. The air pressure during spraying was 30Pa. After spraying, it was quickly transferred to a nitrogen glove box, and annealed on a hot plate at 80°C for 30min to obtain a perovskite light-absorbing layer;

Step 4: spin-coating to prepare a PTAA hole transport layer (for the method, please refer to Document 3);

Step 5: Complete the vacuum thermal deposition of the Al electrode with reference to the step 5 of Example 1;

The battery performance analysis in Example 9 is shown in Table 5:

Table 5 is the performance parameters of the battery obtained in Example 9

V_OC(V) J_SC(mA/cm²) FF PCE (%) 0.98 17.84 0.67 11.71

Example 10

Combining the secondary film formation process with the blade coating technology, a perovskite film with Cs, MA, and FA ternary cation blends was prepared, and it was prepared into a structure of ITO/SnO ₂ /PVSK/Sprio-OMeTAD/Ag. Perovskite solar cells.

Step 1: Refer to the method of Step 1 of Example 8 to prepare glass/ITO/SnO ₂ ;

Step 2: Refer to Step 2 of Example 9 to prepare a CsPbBr ₃ nanocrystalline thin film;

Step 3: Dissolve FAI:MABr:CsI:PbI2:PbBr2 in a mixed solvent of DMF:DMSO (v/v, 4: ₁ ) in a molar ratio of ₁ :0.02:0.0075:1.1:0.22 at 50°C Dissolve for more than 1 hour to obtain a ternary blended perovskite solution for later use;

Step 4: using the solution to perform blade coating on the above nanocrystalline thin film to prepare a perovskite light absorbing layer. On the substrate at 120 °C, the blade coating was started at a speed of 10 mm/s, where the distance between the blade and the substrate was 160 μm, and the perovskite film was obtained by annealing at 120 °C hot plate for 45 s.

Referring to steps 5-6 of Example 8 to complete the preparation of the hole transport layer and electrode; the battery performance analysis in Example 10 is shown in Table 6:

Table 6 is the performance parameters of the battery obtained in Example 10

V_OC(V) J_SC(mA/cm²) FF PCE (%) 1.09 21.24 0.64 14.82

Example 11

The secondary film formation process was applied to flexible perovskite cells based on flexible silver grids, and the perovskite structure was PET/Ag-grid/PH1000:Ammonia:PEI/PEDOT:PSS/PVSK/PCBM/Al Solar battery.

Step 1: Preparation of PET/Ag-grid/PH1000: Ammonia: PEI/PEDOT: PSS substrate (Ref. 5, JieW, Fei F, Luo Q, et a1. Modification of the Highly Conductive PEDOT: PSS Layer for Use in Silver Nanogrid Electrodes for Flexible Inverted Polymer Solar Cells[J].Acs Appl Mater Interfaces, 2017, 9(8): 7834-7842.)

Step 2: Refer to steps 1-5 of Example 1 to complete the device preparation; the battery performance analysis in Example 11 is shown in Table 7:

Table 7 is the performance parameters of the battery obtained in Example 11

V_OC(V) J_SC(mA/cm²) FF PCE (%) 1.01 20.43 0.75 15.33

Example 12

The secondary film formation process combined with the two-step method was used to prepare the perovskite thin film and applied it to the perovskite cell device with the structure of ITO/SnO ₂ /PVSK/Spiro-OMeTAD/Ag;

Step 1: Prepare a perovskite precursor solution by referring to the method in Step 1 of Example 1; in addition, dissolve 1.3 mmol PbI ₂ in a mixed solvent of DMF:DMSO=9.5:0.5, and dissolve at 75 ° C to obtain a PbI ₂ solution; The formula of MABr:MACl=60mg:6mg:6mg is dissolved in 1ml isopropanol to obtain a mixed solution of FA _0.8 MA _0.2 I _0.7 Br _0.1 Cl _0.2 ;

Step 2: Prepare the perovskite pre-set film with reference to the method in Step 2 of Example 1;

Step 3: Spin-coat PbI2 solution at 1500rpm for 30s on the pre-set film, then after annealing at 70°C for _1min , spin- _{coat FA0.8MA0.2I0.7Br0.1Cl0.2 mixed} solution on it at _1500rpm for 30s _, and then the device was Placed on a hot plate at 150°C for 15min annealing;

Referring to steps 5-6 of Example 8 again, the preparation of the hole transport layer and the electrode was completed; the battery performance analysis in Example 12 is shown in Table 8:

Table 8 is the performance parameters of the battery obtained in Example 12

V_OC(V) J_SC(mA/cm²) FF PCE (%) 1.05 22.85 0.72 17.27

Example 13

FA and MA binary cation mixed-type perovskite battery with NiO _x hole transport layer prepared by secondary film formation method, the structure of which is glass/ITO/NiO _x /PVSK/PCBM/Al;

Step 1: The structure is glass/ITO/NiO _x substrate (see document 6 for the preparation method, Wu Y, Yang X, ChenW, et al. Perovskite solar cells with 18.21% efficiency and area over 1cm ² , fabricated by heterojunction engineering [J ]. Nature Energy, 2016, 1, 16148);

Step ₂ : Dissolve FAI:MABr:PbI2:PbBr2 in a mixed solvent of DMF:DMSO (v/v, 4: ₁ ) in a molar ratio of 1:0.02:1.1:0.22 to prepare a binary blended calcium Titanite precursor solution;

On the above-mentioned substrate, FA and MA binary cation mixed-type perovskite thin films were prepared by referring to steps 3-4 of Example 8, and device preparation was completed by referring to steps 4 and 5 of Example 1; battery performance in Example 13 The analysis is shown in Table 9:

Table 9 is the performance parameters of the battery obtained in Example 13

V_OC(V) J_SC(mA/cm²) FF PCE (%) 1.07 23.76 0.72 18.30

Example 14:

A secondary film formation method and its application to the preparation of a perovskite solar cell with a base structure of FTO/TiO ₂ , the structure of which is FTO/TiO ₂ /PVSK/Spiro-OMeTAD/Ag;

Step 1: Preparation of a substrate with a structure of glass/FTO/ _TiO chlorides[J].Nature Chemistry, 2015, 7(9):703-711.);

Refer to step 2 of Example 13 to prepare a solution, and then refer to steps 3-6 of Example 8 to complete the device preparation process; the battery performance analysis in Example 14 is shown in Table 10:

Table 10 is the performance parameters of the battery obtained in Example 14

V_OC(V) J_SC(mA/cm²) FF PCE (%) 1.10 23.87 0.75 19.69

To sum up, with the preparation method of the perovskite film provided in the embodiment of the present invention, a smoother and flatter perovskite film can be prepared, and its crystal size is smaller and the arrangement is more compact. Therefore, its crystal Fewer defects are more conducive to the transport of carriers, and the overall quality of the film is improved. If it is applied to perovskite solar cells, the cells can have better conversion efficiency and stability. Moreover, the preparation method provided in the embodiment of the present invention can be applied to the substrates of various materials and the preparation of perovskite batteries of various components, and can obtain good results, has good universality, and is economical and practical.

It should be understood that the above-mentioned embodiments are only intended to illustrate the technical concept and characteristics of the present invention, and the purpose thereof is to enable those who are familiar with the art to understand the content of the present invention and implement it accordingly, and cannot limit the protection scope of the present invention. All equivalent changes or modifications made according to the spirit of the present invention should be included within the protection scope of the present invention.

Claims (16)

1. a kind of preparation method of perovskite thin film, including preparing the first step of the first perovskite thin film layer and in the first calcium titanium The second step of the second perovskite thin film layer is prepared in mine film layer, which is characterized in that the second step includes: at least to adopt Perovskite precursor solution is set to form the second perovskite thin film layer on the first perovskite thin film layer with solwution method.

2. preparation method according to claim 1, it is characterised in that: the first perovskite thin film layer, the second perovskite Film layer is perovskite polycrystal film, and the perovskite precursor solution used in the second step can be by described One perovskite thin film layer is partly dissolved.

3. preparation method according to claim 1, it is characterised in that: the solwution method includes rubbing method or print process.

4. preparation method according to claim 3, it is characterised in that: the rubbing method include spin-coating method, scraper for coating method, Slot coated method or spray coating method；Alternatively, the print process includes gravure printing method, adagio print process or ink jet printing method.

5. preparation method according to claim 1, which is characterized in that the second step further include: by the calcium Titanium ore precursor solution is coated on the first perovskite thin film layer and is formed after coating, and the coating of Xiang Suoshu applies anti-molten Agent forms perovskite thin film layer.

6. preparation method according to any one of claims 1-5, it is characterised in that specifically include: being obtained to by second step To the second perovskite thin film layer make annealing treatment, annealing temperature is 80-150 DEG C, and annealing time 45s-30min obtains Obtain the perovskite thin film.

7. preparation method according to claim 1, it is characterised in that: the solute component packet of the perovskite precursor solution Include the halide ion of positive monovalent cation, positive bivalent cation and negative one valence；Preferably, the positive monovalent cation includes caesium Any one in ion, first ammonium ion, first miaow ion etc. or two or more combinations；Preferably, the positive bivalent cation Including any one or the two or more combinations in lead ion, tin ion etc.；Preferably, the halide ion packet of the negative one valence Include chloride ion, bromide ion, any one or two or more combinations in iodide ion；And/or the perovskite precursor solution In solvent include dimethyl sulfoxide, gamma-butyrolacton, any one or two or more combinations in dimethylformamide；With/ Or, the concentration of the perovskite precursor solution is 1-1.5mol/L.

8. preparation method according to claim 1, characterized by comprising: heavy using chemical deposition and/or physics Product method prepares to form the first perovskite thin film layer.

9. according to claim 1, preparation method described in 2,3,4,5,7 or 8, it is characterised in that: first perovskite thin film Layer is identical or not identical as the material of the second perovskite thin film layer.

10. according to claim 1, preparation method described in 2,3,4,5,7 or 8, it is characterised in that specifically include: being made in substrate Standby to form the first perovskite thin film layer, the substrate includes flexible or rigid organic conductive substrate or inorganic conductive base Bottom；Preferably, the substrate includes being formed with hole or electron-transporting type organic semiconductor thin-film or inorganic semiconductor film；It is excellent Choosing, the material of the hole-transporting type organic semiconductor thin-film include Polyglycolic acid fibre-poly- (styrene sulfonate) or Poly- [bis- (4- phenyl) (2,4,6- trimethylphenyl) amine]；Preferably, the material of the hole-transporting type inorganic semiconductor film Including nickel oxide；Preferably, the material of the electron-transporting type inorganic semiconductor film includes titanium oxide or tin oxide；It is preferred that , the substrate includes the compliant conductive electrode of ito glass, FTO glass or plastics base.

11. the perovskite thin film prepared by method of any of claims 1-10.

12. perovskite thin film according to claim 11, it is characterised in that: the chemical formula of the perovskite thin film is ABX₃, Wherein A is positive monovalent cation, and B is positive bivalent cation, and X is negative the halide ion of monovalence；Preferably, A includes cesium ion, first Any one in ammonium ion, first miaow ion or two or more combinations；B includes lead ion and/or tin ion, X include chlorine from Son, bromide ion, any one or two or more combinations in iodide ion.

13. perovskite thin film as described in any one of claim 11-12 is in preparing the purposes in electrooptical device.

14. a kind of photoelectric device, it is characterised in that including perovskite thin film described in any one of claim 11-12.

15. photoelectric device according to claim 14, it is characterised in that: the photoelectric device includes solar battery, light Electric transducer, electroluminescent device or X-ray sensor.

16. a kind of device comprising in perovskite thin film described in any one of claim 11-12 or claim 14-15 Described in any item photoelectric devices.