CN113078264A

CN113078264A - Full-coverage perovskite thin film and preparation method thereof

Info

Publication number: CN113078264A
Application number: CN202110326584.1A
Authority: CN
Inventors: 李燕; 贺红; 肖美霞; 王磊; 朱世东; 郑佳璐
Original assignee: Xian Shiyou University
Current assignee: Xian Shiyou University
Priority date: 2021-03-26
Filing date: 2021-03-26
Publication date: 2021-07-06

Abstract

The invention discloses a full-coverage perovskite thin film and a preparation method thereof, and PbI is added₂Powder and CH₃NH₃I, mixing the powder, adding a solvent, and magnetically stirring to obtain completely reacted CH₃NH₃PbI₃A precursor; will CH₃NH₃PbI₃And dropwise adding the precursor on an FTO substrate, and performing spin coating treatment by using an anti-solvent method to obtain the full-coverage perovskite thin film. The invention effectively improves the optical characteristics of the light absorption layer of the perovskite cell, and solves the limitation that the perovskite solar cell in the prior art needs to prepare a compact perovskite thin film with large grain size and no pin hole in an inert device; simple operation and low cost.

Description

Full-coverage perovskite thin film and preparation method thereof

Technical Field

The invention belongs to the technical field of solar cells, and particularly relates to a full-coverage perovskite thin film and a preparation method thereof.

Background

Fossil fuels are one of the major factors causing global warming, and in order to solve this problem, it is necessary to develop clean energy that is easily available and sustainable. Unlike fossil fuels, the sun is an inexhaustible energy source, and the energy transmitted to the earth for 1h exceeds the energy consumed by the whole earth for one year, so that the photovoltaic cell is used for collecting energy from the sun and converting the energy into electric energy, and the solar energy is an effective link clean energy supply mode. Over the past two decades, third generation solar cells, such as dye-sensitized solar cells, quantum dot solar cells, organic solar cells, and perovskite solar cells, have received much attention from researchers. Particularly, perovskite solar cells have excellent visible near-infrared absorption capacity, long charge carrier diffusion distance, bipolar charge transmission capacity and low preparation cost, and the conversion efficiency of the perovskite solar cells is greatly improved to 25.2% within 10 years since the perovskite solar cells are first reported in 2009, which completely meets the efficiency requirement of photovoltaic cell industrialization.

However, the industrialization requires that the perovskite thin film as the core functional layer of the perovskite solar cell must be prepared in the atmospheric environment. While atmospheric moisture will reduce CH₃NH₃PbI₃Coverage of film, increase of CH₃NH₃PbI₃The roughness of the film; reduction of CH by oxygen₃NH₃PbI₃The wettability of the precursor solution on the substrate further reduces CH₃NH₃PbI₃Coverage of the film. Thus, the preparation of a full coverage CH in an atmospheric environment₃NH₃PbI₃Thin films present a great challenge to control of crystallization behavior during spin coating.

Disclosure of Invention

The invention aims to solve the technical problem that the defects in the prior art are overcome, and the full-coverage perovskite thin film and the preparation method thereof are provided, so that the optical characteristics of the light absorption layer of the perovskite cell are effectively improved, and the limitation that the perovskite solar cell in the prior art needs to prepare a dense perovskite thin film with large grain size and no pinholes in an inert device is solved; the preparation method is simple to operate and low in cost; for laboratories without inert processing equipment (such as dry boxes or glove boxes), large-scale industrialization in particular will come.

The invention adopts the following technical scheme:

a process for preparing the full-covered perovskite film from PbI₂Powder and CH₃NH₃I, mixing the powder, adding a solvent, and magnetically stirring to obtain completely reacted CH₃NH₃PbI₃A precursor; will CH₃NH₃PbI₃And dropwise adding the precursor on an FTO substrate, and performing spin coating treatment by using an anti-solvent method to obtain the full-coverage perovskite thin film.

In particular, PbI₂Powder and CH₃NH₃The ratio of the amounts of substances of I is 1: 1 to 3.

Specifically, the magnetic stirring time is 30-60 min, and the stirring is stopped when the color of the mixed powder turns yellow.

Specifically, the solvent is any one of N, N-dimethylformamide, γ -butyrolactone or dimethyl sulfoxide.

In particular, PbI₂Powder and CH₃NH₃The mass ratio of the mixed I powder to the solvent is 1: 1 to 3.

Specifically, the spin coating treatment specifically comprises:

will CH₃NH₃PbI₃The precursor is dripped on an FTO substrate, spin-coating is carried out for 10-15 s at 1000-1300 r/min, then spin-coating is carried out for 30-35 s at 2000-2300 r/min, and finally, an anti-solvent is dripped for 10-20 s.

Further, the anti-solvent is chlorobenzene.

Specifically, annealing the full-coverage perovskite thin film obtained by spin coating treatment at 80-120 ℃ for 30-60 min.

According to another technical scheme, the full-coverage perovskite thin film is prepared according to the method.

Specifically, the surface roughness of the full-coverage perovskite thin film is less than 20nm, and the thickness of the full-coverage perovskite thin film is 100 nm-100 mu m; the grain diameter of the full-covering perovskite film is 10 nm-1 mu m.

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

the invention relates to a preparation method of a full-coverage perovskite film, which is to mix PbI₂Powder and CH₃NH₃I, mixing the powder, adding a solvent, and magnetically stirring to obtain completely reacted CH₃NH₃PbI₃A precursor; will CH₃NH₃PbI₃And dropwise adding the precursor on an FTO substrate, and performing spin coating treatment by using an anti-solvent method to obtain the full-coverage perovskite thin film. The anti-solvent and the solvent in the perovskite precursor have good intersolubility, but the anti-solvent can not dissolve the perovskite solute, so that the anti-solvent can extract the solvent in the perovskite precursor in the spin coating process, the nucleation and the grain growth of the perovskite precursor are accelerated by supersaturating the perovskite solute, the grain size of the grains is large and the grains are uniformly distributed, and the thin film with high coverage rate is formed.

Further, PbI₂Powder and CH₃NH₃The ratio of the amounts of substances of I is 1: 1-3, the inorganic component is excessive in trace amount, and the inorganic component has a self-passivation function and can passivate defects on the surface of the film. This ratio is confirmed by a large number of experiments, and if the inorganic component or the organic component is excessive, the performance of the battery is degraded.

Further, the precursors are uniformly mixed after being magnetically stirred for 30-60 min, and are fully dissolved to become yellow.

Furthermore, N, N-dimethylformamide, gamma-butyrolactone or dimethyl sulfoxide solvent is a polar solvent, can dissolve indissolvable perovskite solute and can be dissolved with an anti-solvent, thereby being beneficial to film preparation.

Further, the perovskite solute has a certain solubility in the solvent, PbI₂Powder and CH₃NH₃The mass ratio of the mixed I powder to the solvent is 1: the proportion of 1-3 can reach the film forming condition of supersaturated crystallization, and the concentration in the range can well control the crystallization speed to be beneficial to the preparation of the film.

Further, the centrifugal force during spin coating can cause the anti-solvent and the solvent in the precursor to leave the film and make the film uniform. Furthermore, chlorobenzene is the most common anti-solvent and has good repeatability in use; the prepared perovskite thin film has relatively high flatness, obviously larger grain size, compact thin film and no defects such as pinholes and the like.

Further, annealing the full-coverage perovskite thin film obtained by spin coating treatment at the temperature of below 100 ℃ for 30min, and completely removing the solvent in the full-coverage perovskite thin film.

The full-coverage perovskite thin film has the surface roughness of less than 20nm, the thickness of 100 nm-100 mu m and relatively high flatness; the film has crystal grain diameter of 10 nm-1 micron, large crystal grain size, compact structure and no pinhole defect.

In conclusion, the invention effectively improves the optical characteristics of the light absorption layer of the perovskite cell, solves the limitation that the perovskite solar cell in the prior art needs to prepare a compact perovskite thin film without pinholes and with large grain size in an inert device, and has simple operation and low cost.

The technical solution of the present invention is further described in detail by the accompanying drawings and embodiments.

Drawings

FIG. 1 shows the full coverage CH prepared in example 1₃NH₃PbI₃Optical photographs of the films;

FIG. 2 is a XRD result diagram of a perovskite thin film;

FIG. 3 is a graph showing the relative exciton generation rate of 13747.83a.u in example 2;

FIG. 4 is a graph showing the relative exciton generation rate of 11073.17a.u in example 3;

FIG. 5 is a graph showing the relative exciton generation rate of 9338.83a.u in example 4;

FIG. 6 is a graph showing the relative exciton generation rate of 11014a.u in example 5;

fig. 7 is a graph showing the relative exciton generation rate of 13658.33a.u in example 6.

Detailed Description

It will be understood that the terms "comprises" and/or "comprising," when used in this specification and the appended claims, specify the presence of stated features, integers, steps, operations, elements, and/or components, but do not preclude the presence or addition of one or more other features, integers, steps, operations, elements, components, and/or groups thereof.

It is also to be understood that the terminology used in the description of the invention herein is for the purpose of describing particular embodiments only and is not intended to be limiting of the invention. As used in the specification of the present invention and the appended claims, the singular forms "a," "an," and "the" are intended to include the plural forms as well, unless the context clearly indicates otherwise.

It should be further understood that the term "and/or" as used in this specification and the appended claims refers to and includes any and all possible combinations of one or more of the associated listed items.

The invention provides a preparation method of a full-coverage perovskite film, which uses PbI₂And CH₃NH₃I is prepared from raw material CH₃NH₃PbI₃Precursor solution; deposition of CH by spin-coating method₃NH₃PbI₃Film, and adding anti-solvent dropwise during spin coating process to promote CH₃NH₃PbI₃The film is fully covered on the substrate. The invention covers CH completely₃NH₃PbI₃The film has high photoelectric properties such as large grain size, low defect concentration, consistent crystal orientation and the like, and can be prepared in an atmospheric environment. The method has the advantages of strong operability, simplicity, rapidness and easy acquisition of raw materials, provides a technical scheme for researching the development of preparing high-quality perovskite photovoltaic materials in atmospheric environment, and can be widely applied to the fields of nano material synthesis, solution method film preparation, solar cell environmental stability improvement and the like.

The invention relates to a method for preparing a full-coverage perovskite thin film in an atmospheric environment, which comprises the following steps:

s1, configuration CH₃NH₃PbI₃Precursor solution;

weighing PbI₂And CH₃NH₃I powder, and PbI₂And CH₃NH₃The ratio of the amounts of substances of I is 1: 3, mixing the two with N, N-dimethylformamide, gamma-butyrolactone or dimethyl sulfoxide solvent, magnetically stirring for 30-60 min, stopping stirring when the color of the powder is fully yellow, and obtaining the completely reacted CH₃NH₃PbI₃And (3) precursor.

S2 preparation of CH based on crystallization behavior control of anti-solvent method₃NH₃PbI₃A film.

CH prepared in step S1₃NH₃PbI₃Dripping the precursor on an FTO substrate for spin coating, and quickly dripping the antisolvent on the semi-dry CH in the spin coating process₃NH₃PbI₃On the film, chlorobenzene is used as an anti-solvent, and the anti-solvent is used for promoting crystallization to obtain mirror-surface-luster CH₃NH₃PbI₃A film;

In order to completely remove the solvent in the film, the film is annealed at 80-120 ℃ for 30-60 min.

CH prepared by the method of the invention₃NH₃PbI₃Film formed by CH₃NH₃PbI₃The crystal grains are mutually extruded and stacked, no hole is formed in the film, and the film completely covers the surface of the substrate.

CH₃NH₃PbI₃The surface roughness of the film is less than 20nm, and the film presents mirror surface gloss. CH (CH)₃NH₃PbI₃The thickness of the film is 100 nm-100 mu m; CH (CH)₃NH₃PbI₃The diameter of the crystal grain is 10 nm-1 μm.

In order to make the objects, technical solutions and advantages of the embodiments of the present invention clearer, the technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the drawings in the embodiments of the present invention, and it is obvious that the described embodiments are some, but not all, embodiments of the present invention. The components of the embodiments of the present invention generally described and illustrated in the figures herein may be arranged and designed in a wide variety of different configurations. Thus, the following detailed description of the embodiments of the present invention, presented in the figures, is not intended to limit the scope of the invention, as claimed, but is merely representative of selected embodiments of the invention. All other embodiments, which can be derived by a person skilled in the art from the embodiments given herein without making any creative effort, shall fall within the protection scope of the present invention.

Example 1

A method for preparing a full-coverage perovskite thin film in an atmospheric environment comprises the following steps:

step 1: preparation of CH₃NH₃PbI₃Precursor body

Measuring PbI₂In an amount of 1.005g, CH₃NH₃The amount of I was 0.3466g, the amount of DMF was 3ml, magnetic stirring was carried out for 30min, and the solution method was used to dissolve fully and react to give a yellow precursor.

Step 2: deposition of CH₃NH₃PbI₃Film(s)

CH prepared in step S1₃NH₃PbI₃Dropping on FTO substrate, spin-coating at 1000r/min for 10s, then spin-coating at 2000r/min for 30s, pumping 200 μ l chlorobenzene with liquid-transferring gun, and dropping on semi-dry CH rapidly for 15s during final spin-coating₃NH₃PbI₃On the film. Finally, the film is annealed at 80 ℃.

Referring to FIGS. 1 and 2, for preparing a full coverage CH₃NH₃PbI₃Optical photograph of film, CH₃NH₃PbI₃The thickness of the film was 100nm, the roughness was 15nm, and the grain diameter was 0.5. mu.m.

Example 2

A preparation method of a high-quality perovskite thin film in an atmospheric environment comprises the following steps:

step 1: preparation of CH₃NH₃PbI₃Precursor body

Measuring PbI₂In an amount of 1.005g, CH₃NH₃The amount of I was 1.0398gAnd the amount of DMF is 6ml, the mixture is magnetically stirred for 50min, and the yellow precursor is fully dissolved and reacted by a solution method.

Step 2: deposition of CH₃NH₃PbI₃Film(s)

The CH prepared in the last step₃NH₃PbI₃Dropping on FTO substrate, spin-coating at 1000r/min for 10s, then spin-coating at 2000r/min for 30s, pumping 200 μ l CB using pipette gun, and dropping 15s quickly on CH during final spin-coating₃NH₃PbI₃On the film. Finally, the film is annealed at 80 ℃.

Please refer to fig. 3, which is a prepared full coverage CH₃NH₃PbI₃PL characterization of the film, the relative exciton growth rate value was 13747.83a.u. Prepared CH₃NH₃PbI₃The film thickness is 100nm, the roughness is 15nm, and the grain diameter is 0.5 μm.

Example 3

step 1: preparation of CH₃NH₃PbI₃Precursor body

Measuring PbI₂In an amount of 1.005g, CH₃NH₃The amount of I is 0.3466g, the amount of gamma-butyrolactone is 3ml, the mixture is magnetically stirred for 50min, and the yellow precursor is fully dissolved and reacted by a solution method.

Step 2: deposition of CH₃NH₃PbI₃Film(s)

The CH prepared in the last step₃NH₃PbI₃Dropping on FTO substrate, spin-coating at 1000r/min for 15s, then spin-coating at 2000r/min for 35s, pumping 200 μ l CB using pipette gun, and dropping 15s quickly on CH during final spin-coating₃NH₃PbI₃On the film. Finally, the film is annealed at 80 ℃.

Please refer to fig. 4, which is a prepared full coverage CH₃NH₃PbI₃PL characterization of the film, the relative exciton growth rate value was 11073.17a.u. Prepared CH₃NH₃PbI₃The thickness of the film is 100nm and coarseRoughness 15nm and grain diameter 0.6 μm.

Example 4

step 1: preparation of CH₃NH₃PbI₃Precursor body

Measuring PbI₂In an amount of 1.005g, CH₃NH₃The amount of I is 0.3466g, the amount of gamma-butyrolactone is 6ml, the mixture is magnetically stirred for 40min, and the yellow precursor is fully dissolved and reacted by a solution method.

Step 2: deposition of CH₃NH₃PbI₃Film(s)

The CH prepared in the last step₃NH₃PbI₃Dropping on FTO substrate, spin-coating at 1300r/min for 15s, spin-coating at 2300r/min for 35s, pumping 200 μ l CB with liquid-transfer gun, and quickly dropping 15s on CH during final spin-coating₃NH₃PbI₃On the film. Finally, the film is annealed at 80 ℃.

Please refer to fig. 5, which is a prepared full coverage CH₃NH₃PbI₃PL characterization of the film, the relative exciton growth rate value was 9338.83a.u. Prepared CH₃NH₃PbI₃The film thickness is 100nm, the roughness is 10nm, and the grain diameter is 0.5 μm.

Example 5

step 1: preparation of CH₃NH₃PbI₃Precursor body

Measuring PbI₂In an amount of 2.010g, CH₃NH₃The amount of I is 0.6932g, the amount of dimethyl sulfoxide is 3ml, magnetic stirring is carried out for 30min, and the yellow precursor is fully reacted by utilizing solution method.

Step 2: deposition of CH₃NH₃PbI₃Film(s)

The CH prepared in the last step₃NH₃PbI₃Dropping on FTO substrate, spinning at 1000r/min for 15s, and spinning at 2000r/min35s of coating, 200. mu.l of CB was drawn using a pipette gun, and 15s was quickly dropped over CH during the final spin coating₃NH₃PbI₃On the film; finally, the film is annealed at 80 ℃.

Please refer to fig. 6, which is a prepared full coverage CH₃NH₃PbI₃PL characterization of the film, the relative exciton growth rate value was 11014a.u. Prepared CH₃NH₃PbI₃The film thickness is 100nm, the roughness is 12nm, and the grain diameter is 0.5 μm.

Example 6

step 1: preparation of CH₃NH₃PbI₃Precursor body

Measuring PbI₂In an amount of 2.010g, CH₃NH₃The amount of I is 0.6932g, the amount of dimethyl sulfoxide is 6ml, magnetic stirring is carried out for 30min, and the yellow precursor is fully reacted by utilizing solution method.

Step 2: deposition of CH₃NH₃PbI₃Film(s)

The CH prepared in the last step₃NH₃PbI₃Dropping on FTO substrate, spin-coating at 1300r/min for 15s, spin-coating at 2300r/min for 35s, pumping 200 μ l CB with liquid-transfer gun, and quickly dropping 15s on CH during final spin-coating₃NH₃PbI₃On the film; finally, the film is annealed at 100 ℃.

Please refer to fig. 7, which is a prepared full coverage CH₃NH₃PbI₃PL characterization of the film, the relative exciton growth rate value was 13658.33a.u. Prepared CH₃NH₃PbI₃The film thickness is 100nm, the roughness is 9nm, and the grain diameter is 0.5 μm.

In order to increase CH in atmospheric environment₃NH₃PbI₃Various techniques, such as composition processes, additive processes, solvent processes, interfacial processes, etc., have been used to control the crystallization behavior of thin films. In comparison, the solvent process is more convenient and faster, and the anti-solvent can be utilized to control the thickness of the perovskiteThe growth rate of the film, i.e. the use of an anti-solvent to reduce the solubility of the perovskite in other solvents, increases its nucleation rate through supersaturation provided by the anti-solvent, and thus allows the production of dense and pinhole-free perovskite thin films with large grain sizes. The invention selects the chlorobenzene which is most commonly used as the anti-solvent, and compared with other processes for preparing the film, the preparation process related in the invention has two advantages, on one hand, the invention prepares the film in the atmospheric environment, and can solve the problem of preparing the film without inert processing equipment. On the other hand, the chlorobenzene anti-solvent can well control the growth rate of the perovskite thin film and remove residual solvent, and the high-quality perovskite thin film with high surface coverage rate, large grain size, low defect concentration and consistent crystal orientation is prepared.

The above-mentioned contents are only for illustrating the technical idea of the present invention, and the protection scope of the present invention is not limited thereby, and any modification made on the basis of the technical idea of the present invention falls within the protection scope of the claims of the present invention.

Claims

1. A preparation method of a full-coverage perovskite thin film is characterized in that PbI is added₂Powder and CH₃NH₃I, mixing the powder, adding a solvent, and magnetically stirring to obtain completely reacted CH₃NH₃PbI₃A precursor; will CH₃NH₃PbI₃And dropwise adding the precursor on an FTO substrate, and performing spin coating treatment by using an anti-solvent method to obtain the full-coverage perovskite thin film.

2. The method of claim 1, wherein PbI is₂Powder and CH₃NH₃The ratio of the amounts of substances of I is 1: 1 to 3.

3. The method according to claim 1, wherein the magnetic stirring time is 30 to 60min, and the stirring is stopped when the color of the mixed powder turns yellow.

4. The method according to claim 1, wherein the solvent is any one of N, N-dimethylformamide, γ -butyrolactone or dimethylsulfoxide.

5. The method of claim 1, wherein PbI is₂Powder and CH₃NH₃The mass ratio of the mixed I powder to the solvent is 1: 1 to 3.

6. The method according to claim 1, wherein the spin coating process is specifically:

7. The process of claim 1 or 6, wherein the anti-solvent is chlorobenzene.

8. The method according to claim 1, wherein the full-coverage perovskite thin film obtained by the spin coating treatment is annealed at 80-120 ℃ for 30-60 min.

9. A full-coverage perovskite thin film prepared according to the method of claim 1.

10. The fully-covered perovskite thin film according to claim 9, wherein the surface roughness of the fully-covered perovskite thin film is less than 20nm, and the thickness of the fully-covered perovskite thin film is 100nm to 100 μm; the grain diameter of the full-covering perovskite film is 10 nm-1 mu m.