CN113584436A

CN113584436A - Perovskite thin film based on non-solvent, preparation method and application

Info

Publication number: CN113584436A
Application number: CN202110866416.1A
Authority: CN
Inventors: 陈永生; 郭海中; 刘林林; 王嘉铭
Original assignee: Zhengzhou University
Current assignee: Zhengzhou University
Priority date: 2021-07-29
Filing date: 2021-07-29
Publication date: 2021-11-02
Anticipated expiration: 2041-07-29
Also published as: CN113584436B

Abstract

The invention discloses a perovskite thin film based on a non-solvent, a preparation method and application, and belongs to the technical field of semiconductor materials. The method comprises the following steps: mixing powder raw materials in a certain proportion, and treating at 200-300 ℃ for 0.5-1.5 h to obtain reacted mixed powder; depositing the reacted mixed powder on a preset substrate by adopting an electron beam evaporation method under a vacuum condition to obtain a perovskite thin film; and annealing the obtained perovskite thin film for 5-50 min at 100-450 ℃ to obtain the high-quality perovskite thin film. The method provided by the invention does not need the participation of a solvent, and has simple processControllable CsPbBr₃And (3) preparing a film.

Description

Perovskite thin film based on non-solvent, preparation method and application

Technical Field

The invention belongs to the technical field of semiconductor materials, and particularly relates to a perovskite thin film based on a non-solvent, a preparation method and application.

Background

In recent years, organic-inorganic hybrid perovskite materials have great application potential in the fields of solar cells, diodes, photodetectors, lasers, field effect transistors and the like due to excellent performance, and the application of the materials in the field of solar cells naturally becomes the research content of numerous scientists. Since 2009, its conversion efficiency has increased from 3.8% to 25.5% in as little as a decade. Although the photoelectric conversion efficiency of the organic photoelectric conversion material is rapidly developed, the organic component at the A site of the organic photoelectric conversion material is easily degraded by moisture, heat and light, so that the efficiency of the organic photoelectric conversion material is attenuated and unstable. And the all-inorganic perovskite does not contain organic components, so that the thermal stability of the perovskite is greatly improved. Especially CsPbBr₃Has excellent stability due to larger tolerance factor. The theoretical limit efficiency of the battery is 16.37%, the maximum efficiency of the current laboratory is 10.91%, and the open-circuit voltage can reach 1.7V. Such high open circuit voltage and excellent stability may allow it to be used as the top cell of a laminate cell, particularly a 4 terminal laminate cell. Thus CsPbBr₃The research of perovskite is still of great significance.

The existing method for preparing the perovskite film is a solvent method, so that the cost is low and the operation is simple and convenient; however, its disadvantages are also apparent, such as non-uniform film formation, toxic solvents, environmental hazards, etc. In the preparation of CsPbBr₃In the case of thin films, organic solvents commonly used by CsBr, such as dimethyl sulfoxide (DMSO), dimethyl formamide (DMF) and the like, have low medium solubility, and it is difficult to prepare compact and high-quality CsPbBr by adopting a one-step solution method₃Thin films are relatively prone to generate impurity phases when a multi-step solution process is employed. In addition, when large-area devices are prepared, a uniform and dense film is difficult to form by a solution method, and the surface appearance is poor. When a multi-source vacuum evaporation method is adopted, deposition parameters are difficult to control, and the operation is complicated.

Disclosure of Invention

Aiming at the defects of the method, the invention provides a method for preparing a perovskite thin film based on a non-solvent, which does not need a solvent, has a simple process and can controllably carry out CsPbBr₃And (3) preparing a film.

The first purpose of the invention is to provide a method for preparing a perovskite thin film based on a non-solvent, which comprises the following steps:

mixing powder raw materials in a certain proportion, and treating at 200-300 ℃ for 0.5-1.5 h to obtain reacted mixed powder;

depositing the reacted mixed powder on a preset substrate by adopting an evaporation method under a vacuum condition to obtain a perovskite thin film;

and annealing the obtained perovskite thin film for 5-50 min at 100-450 ℃ to obtain the annealed perovskite thin film.

Preferably, the raw materials are CsBr and PbBr of powder₂。

More preferably, the CsBr and PbBr are₂The molar ratio is 1-2: 1.

more preferably, the perovskite thin film is CsPbBr₃A film.

Preferably, the evaporation method is electron beam evaporation.

More preferably, the evaporation method adopts an electron beam evaporation method, and the flow of the evaporation beam is adjusted to be 1-10 mA.

Preferably, the substrate is treated prior to use according to the following steps:

soaking the substrate into deionized water, and dipping a cotton swab in the liquid detergent to wipe the surface of the substrate; and then sequentially carrying out ultrasonic treatment on the substrate in deionized water, acetone, alcohol and isopropanol for 8-12 min, naturally airing the substrate after the ultrasonic treatment is finished, and finally irradiating the substrate for 8-12 min by using an ultraviolet lamp.

More preferably, the substrate is a quartz glass substrate or fluorine-doped SnO₂Conductive glass.

It is a second object of the present invention to provide a perovskite thin film.

The third purpose of the invention is to provide the application of the perovskite thin film in the solar cell.

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

the invention firstly mixes and grinds the predecessor according to a certain proportion, and then grinds the powderAnd putting the powder into a reaction kettle for heating reaction. Then the prepared powder is used as a target material to prepare CsPbBr by deposition in an electron beam high vacuum environment₃A film. The subsequent annealing is to further optimize the film quality.

The preparation method provided by the invention has the advantages that the whole process is clean, simple and controllable, in the early mixing process, the raw materials are mixed and reacted, and then the mixture is heated and reacted, so that the mixture is further reacted, the use of toxic solvents is avoided in the process, the content of powder precursors after high-temperature reaction is reduced, and the improvement of the crystallinity of the film prepared by later evaporation is facilitated. The quality of the film can be improved by adopting electron beam evaporation coating, so that the film is more uniform and compact. The post-annealing treatment can optimize the quality of the film, improve the crystallinity and increase the grain size.

The method provided by the invention enables CsPbBr to be used₃The film has excellent stability in air.

The invention has the advantages of easily obtained raw materials and simple operation, and meets the requirements of commercial production.

Drawings

FIG. 1 is a schematic diagram of a process for preparing a perovskite thin film according to an embodiment.

FIG. 2 shows CsPbBr constructed in application example 1₃The structure diagram (a) and the physical diagram (b) of the battery.

FIG. 3 shows the annealed CsPbBr provided in examples 1 to 6₃Thin films and unannealed CsPbBr in example 1₃X-ray diffraction test pattern of the film (as-prepared).

FIG. 4 shows the annealed CsPbBr provided in examples 1 to 6₃Thin films and unannealed CsPbBr in example 1₃Ultraviolet-visible (UV-Vis) transmission spectrum of the film (as-prepared).

FIG. 5 shows the annealed CsPbBr provided in examples 1 to 6₃Thin films and unannealed CsPbBr in example 1₃Photoluminescence (PL) test spectra of the films (as-prepared).

FIG. 6 shows the annealed CsPbBr provided in examples 1 to 6₃Thin films and unannealed CsPbBr in example 1₃Scanning Electron Microscope (SEM) photograph of the film (as-prepared).

FIG. 7 shows a solar cell and a solar cell using the same, which are provided in embodiments 1 to 4 and which employ non-annealed CsPbBr₃I-V curves of solar cells (as-prepared) made of thin films.

FIG. 8 shows a solar cell provided in application example 1 and application examples 5 to 8, and a solar cell using non-annealed CsPbBr₃I-V curves of solar cells (as-prepared) made of thin films.

FIG. 9 shows the annealed CsPbBr samples provided in examples 11 to 14₃Thin films and unannealed CsPbBr in example 11₃X-ray diffraction test pattern of the film (as-prepared).

FIG. 10 shows the annealed CsPbBr samples provided in examples 11 to 14₃Thin films and unannealed CsPbBr in example 11₃Ultraviolet-visible (UV-Vis) transmission spectrum of the film (as-prepared).

FIG. 11 shows the annealed CsPbBr samples provided in examples 11 to 14₃Thin films and unannealed CsPbBr in example 11₃Photoluminescence (PL) test spectra of the films (as-prepared).

FIG. 12 shows the annealed CsPbBr samples provided in examples 11 to 14₃Thin films and unannealed CsPbBr in example 11₃Scanning Electron Microscope (SEM) photograph of the film (as-prepared).

FIG. 13 shows solar cells according to embodiments 9-12 and non-annealed CsPbBr₃I-V curves of solar cells (as-prepared) made of thin films.

FIG. 14 shows a solar cell provided in application example 11 and application examples 13 to 17, and a solar cell using non-annealed CsPbBr₃I-V curves of solar cells (as-prepared) made of thin films.

Detailed Description

In order to make the technical solutions of the present invention better understood and implemented by those skilled in the art, the present invention is further described below with reference to the following specific embodiments and the accompanying drawings, but the embodiments are not meant to limit the present invention.

The purity of the CsBr powder used in the following examples is not less than 99.9%; PbBr₂Purity of powderNot less than 99.9%; other reagents and materials, if not specifically stated, are commercially available; the experimental methods are all conventional methods unless otherwise specified.

Example 1

A method for preparing a perovskite thin film based on a non-solvent, see fig. 1, comprising the steps of:

soaking the quartz glass substrate into deionized water to remove dust on the surface of the substrate. Then, the surface of the substrate was wiped with a cotton swab dipped with a detergent. And then, respectively carrying out ultrasonic treatment on the cleaned substrate for 10min by using deionized water, acetone, alcohol and isopropanol, naturally airing the substrate after the ultrasonic treatment is finished, and finally irradiating the substrate for 10min by using an ultraviolet lamp (UV).

Weighing CsBr: PbBr₂Pouring the raw materials with the molar ratio of 1:1 into a mortar for mixing and grinding, and grinding to orange yellow without adding any solution, which indicates that the raw materials react; then pouring the mixed powder into the inner liner of the reaction kettle, screwing down the reaction kettle to form a closed space without adding any solution, placing the reaction kettle in a forced air drying oven for reaction at 250 ℃ for 1h, and taking out the reaction kettle for later use after the reaction kettle is cooled to room temperature;

fixing the glass substrate on a substrate holder of an electron beam evaporation coating machine by using a high temperature resistant adhesive tape, placing a crucible which takes mixed powder after reaction of a reaction kettle as a target material on a target platform, adjusting the distance between the substrate holder and the target platform, closing a vacuum chamber, and pumping the pressure of the vacuum chamber to 4.0 multiplied by 10 during coating^-4Pa, turning on an evaporation power supply, setting a manual plating program, preheating a machine for 5min, starting an electron gun to heat an evaporation target, setting the filament current to be 0.5A and the filament voltage to be 105-plus 110V, adjusting the evaporation beam current to be 1mA, the evaporation time to be 1min, adjusting the evaporation beam current to be 2mA, the evaporation time to be 30S, adjusting the evaporation beam current to be 3mA, the evaporation time to be 30S, adjusting the evaporation beam current to be 4mA, the evaporation time to be 1min, adjusting the evaporation beam current to be 5mA, and the evaporation time to be 5 min; after the deposition is finished, the plating procedure is manually closed, nitrogen is filled into the vacuum chamber, the air vent is opened, and CsPbBr is taken out₃A film.

The deposited CsPbBr₃The film is put into a porcelain boat, a program is set in a muffle furnace according to the target temperature and the target time,and annealing is carried out. Setting the annealing time to be 10min and the annealing temperature to be 300 ℃ in sequence; when the annealing process is finished, the temperature is automatically reduced, when the film is cooled to a greenhouse, the muffle furnace is opened, and CsPbBr is taken out₃A perovskite thin film.

Example 2

The same as in example 1 except that the annealing temperature was 100 ℃.

Example 3

The same as in example 1 except that the annealing temperature was 200 ℃.

Example 4

The same as in example 1 except that the annealing temperature was 350 ℃.

Example 5

The same as in example 1 except that the annealing temperature was 400 ℃.

Example 6

The same as in example 1 except that the annealing temperature was 450 ℃.

Example 7

Same as example 1 except that the annealing time was 5 min.

Example 8

The same as in example 1, except that the annealing time was 20 min.

Example 9

Same as example 1 except that the annealing time was 30 min.

Example 10

Same as example 1 except that the annealing time was 40 min.

Example 11

Same as example 1, except that CsBr: PbBr₂In a molar ratio of 2: 1.

Example 12

The same as in example 11 except that the annealing temperature was 250 ℃.

Example 13

The same as in example 11 except that the annealing temperature was 350 ℃.

Example 14

The same as in example 11 except that the annealing temperature was 400 ℃.

Application example 1

An application of a perovskite thin film based on a non-solvent in a solar cell is shown in figures 1-2, and a preparation method of applying the perovskite thin film based on the non-solvent in the solar cell is as follows:

etching fluorine-doped SnO₂Soaking a conductive glass (FTO) substrate into deionized water to remove dust on the surface of the substrate. Then, the surface of the substrate was wiped with a cotton swab dipped with a detergent. And then, respectively carrying out ultrasonic treatment on the cleaned substrate for 10min by using deionized water, acetone, alcohol and isopropanol, naturally airing the substrate after the ultrasonic treatment is finished, and finally irradiating the substrate for 10min by using an ultraviolet lamp (UV).

And brushing the beaker by using a test tube brush and detergent, then ultrasonically cleaning the beaker by using deionized water, and naturally drying the beaker. Adding ice-water mixture to 100mL mark in beaker, placing on magnetic stirrer, slowly dropping 2.2mL refrigerated TiCl while stirring₄The solution was slowly added dropwise in 22 portions, followed by stirring at room temperature for 30 min. After stirring, sticking the cleaned FTO to the edge by using a high-temperature resistant adhesive tape to prevent TiO from being deposited completely₂After the film is formed, the subsequently prepared battery is short-circuited. Then immersing TiCl right side up₄In the solution, the mouth was sealed. Then putting the mixture into a constant-temperature water bath kettle, and carrying out water bath at 70 ℃. After the water bath is finished, the adhesive tape is removed, the surface of the adhesive tape is washed by deionized water and absolute ethyl alcohol respectively, and then the adhesive tape is dried by high-purity nitrogen for later use.

Weighing CsBr: PbBr₂Pouring the raw materials with the molar ratio of 1:1 into a mortar for mixing and grinding, and grinding to orange yellow without adding any solution, which indicates that the raw materials react; and then pouring the mixed powder into the inner liner of the reaction kettle, wherein no solution is required to be added in the step, screwing down the reaction kettle to form a closed space, placing the reaction kettle in a forced air drying oven for reaction at 250 ℃, and taking out the reaction kettle for later use after the reaction kettle is cooled to room temperature.

By depositing over TiO₂The FTO of the film is fixed on a substrate frame of an electron beam evaporation coating machine, and the reacted mixture of the reaction kettle is mixedPlacing the crucible with powder as target material on the target table, adjusting the distance between the substrate holder and the target table, closing the vacuum chamber, and pumping the vacuum chamber to 4.0 × 10 during plating^-4Pa, turning on an evaporation power supply, setting a manual plating program, preheating a machine for 5min, starting an electron gun to heat an evaporation target, setting the filament current to be 0.5A and the filament voltage to be 105-plus 110V, adjusting the evaporation beam current to be 1mA, the evaporation time to be 1min, adjusting the evaporation beam current to be 2mA, the evaporation time to be 30S, adjusting the evaporation beam current to be 3mA, the evaporation time to be 30S, adjusting the evaporation beam current to be 4mA, the evaporation time to be 1min, adjusting the evaporation beam current to be 5mA, and the evaporation time to be 5 min; after the deposition is finished, the plating procedure is manually closed, nitrogen is filled into the vacuum chamber, the air vent is opened, and CsPbBr is taken out₃A film.

The deposited CsPbBr₃The film is placed in a porcelain boat and annealed in a muffle furnace according to a target temperature and a target time setting program. Setting the annealing time to be 10min and the annealing temperature to be 300 ℃; when the annealing process is finished, the temperature is automatically reduced, when the film is cooled to a greenhouse, the muffle furnace is opened, and CsPbBr is taken out₃A perovskite thin film.

Annealed CsPbBr deposited with tape-out₃Coating the carbon slurry on the surface of the absorption layer by using a thin film FTO non-electrode part; standing for 30min, and annealing at 100 deg.C for 30 min. Obtaining the perovskite thin-film solar cell device based on the non-solvent, wherein the effective area of the device is 0.06cm². Fig. 2 shows a structural diagram (a) and a physical diagram (b) of the constructed battery.

Application example 2

Same as in application example 1, except that CsPbBr₃The temperature of the film annealing was 100 ℃.

Application example 3

Same as in application example 1, except that CsPbBr₃The temperature of the film annealing was 200 ℃.

Application example 4

Same as in application example 1, except that CsPbBr₃The temperature of the film annealing was 350 ℃.

Application example 5

And applications thereofExample 1 the same, except that CsPbBr₃The film annealing time is 5 min.

Application example 6

Same as in application example 1, except that CsPbBr₃The film annealing time is 20 min.

Application example 7

Same as in application example 1, except that CsPbBr₃The film annealing time is 30 min.

Application example 8

Same as in application example 1, except that CsPbBr₃The film annealing time is 40 min.

Application example 9

Same as in application example 1, except that the non-solvent-based perovskite thin film is applied to the preparation method of the solar cell, CsBr: PbBr₂In a molar ratio of 2: 1.

Application example 10

Same as in application example 9, except that CsPbBr₃The temperature of the film annealing was 250 ℃.

Application example 11

Same as in application example 9, except that CsPbBr₃The temperature of the film annealing was 350 ℃.

Application example 12

Same as in application example 9, except that CsPbBr₃The temperature of the film annealing was 400 ℃.

Application example 13

Same as in application example 11, except that CsPbBr₃The film annealing time is 5 min.

Application example 14

Same as in application example 11, except that CsPbBr₃The film annealing time is 15 min.

Application example 15

Same as in application example 11, except that CsPbBr₃The film annealing time is 20 min.

Application example 16

Same as in application example 11, except that CsPbBr₃The film annealing time is 30 min.

Application example 17

Same as in application example 11, except that CsPbBr₃The film annealing time is 40 min.

In order to illustrate the relevant performance of the perovskite thin film obtained by the method for preparing the perovskite thin film based on the non-solvent, the relevant performance of the all-inorganic Pb-based perovskite thin film prepared in the embodiments 1 to 4 is tested, and is shown in the figures 3 to 14 and tables 1 to 4.

FIG. 3 shows the annealed CsPbBr provided in examples 1 to 6₃Thin films and unannealed CsPbBr in example 1₃X-ray diffraction test pattern of the film (as-prepared);

as can be seen from FIG. 3, the diffraction peak of the directly deposited thin film at 11.73 ℃ is corresponding to CsPb₂Br₅(002) crystal orientation; diffraction peaks appearing at 15.18 °, 21.58 °, 30.48 °, 30.82 °, 34.36 ° and 38.04 ° are CsPbBr₃Crystal orientations (PDF #54-0751) of (101), (121), (040), (202), (222) and (123). This indicates that the film is CsPb₂Br₅And CsPbBr₃The mixed film of (4). CsPb at lower annealing temperatures₂Br₅The intensity of the (002) diffraction peak of (a) increases with increasing temperature; the annealing temperature is increased to 300 ℃, and the diffraction peak intensity is sharply reduced; after annealing at 350 ℃, the diffraction peak completely disappeared. This indicates that CsPb was present at 300 deg.C₂Br₅Thermal decomposition occurs to generate CsPbBr₃And PbBr₂And PbBr₂Because of its low melting point, it is vaporized and volatilized at high temperature to be removed. CsPbBr₃The components are present in the film in an orthogonal phase. When the annealing temperature is relatively low, the diffraction peak intensities of (101) and (202) crystal directions are reduced along with the increase of the temperature; when the annealing temperature is higher than 300 ℃, the annealing temperature is increased. (121) And (123) the diffraction intensity of the crystal orientation increases with increasing annealing temperature; however, when the annealing temperature reached 450 ℃, the two crystallographic orientation diffraction peaks disappeared.

FIG. 4 shows the annealed CsPbBr provided in examples 1 to 6₃Thin films and unannealed CsPbBr in example 1₃Ultraviolet-visible (UV-Vis) transmission spectrum of the film;

as can be seen from FIG. 4, CsPbBr₃The absorption edge of the film is at 528nm, which corresponds to a band gap of 2.34 eV. As can be seen, the absorption edge is slightly red-shifted with increasing annealing temperature, and the band gap is about 2.3eV at 400 ℃ and 450 ℃. The absorption strength tends to be enhanced and then weakened along with the increase of the annealing temperature, and the absorption strength of the film is strongest after the annealing at 300 ℃. When the annealing temperature is more than 300 ℃, the absorption strength of the film is reduced, and particularly, the absorption strength in the short-wave range is weakened.

FIG. 5 shows the annealed CsPbBr provided in examples 1 to 6₃Thin films and unannealed CsPbBr in example 1₃Photoluminescence (PL) test spectrum of the thin film;

as can be seen from FIG. 5, the photoluminescence intensity of the thin film gradually increases with the increase of the annealing temperature, and the peak intensity of the luminescence reaches the maximum when the annealing is carried out at 450 ℃, which shows that the defects of the thin film decrease with the increase of the annealing temperature. The PL spectrum luminescence peak is gradually red-shifted with the annealing temperature, and is consistent with the change trend of the absorption spectrum. Indicating that post annealing improves film quality.

FIG. 6 shows the annealed CsPbBr provided in examples 1 to 6₃Thin films and unannealed CsPbBr in example 1₃Scanning Electron Microscope (SEM) photographs of the thin film;

as can be seen from fig. 6, since the incident atomic energy during the room temperature deposition process is low and the number of critical crystal nuclei is large during the film formation process, many crystal grains with smaller grain size are formed, and the grain size of the film does not change much after the 100 ℃ annealing. As the annealing temperature increases, the grains grow gradually. After annealing at 200 ℃, crystal grains are obviously increased compared with the prior crystal grains, which shows that atoms obtain energy from the outside to generate body diffusion and the crystal grains are gradually fused and grown in the annealing process of the film. When the annealing temperature reaches 300 ℃, crystal grains become larger obviously, the crystal grains with the average size of 1 mu m are closely connected, and the film surface is flatter. The annealing temperature is further increased and the film grains continue to grow, but a bare substrate appears, indicating further diffusion of atoms. In the figure, small grains exist at the grain boundaries after annealing at 350 ℃, and no small grains exist at the grain boundaries after annealing at 400 ℃. The annealing temperature is further increased and the pores are enlarged. Indicating that annealing increases grain size and changes film morphology.

FIG. 7 shows a solar cell and a solar cell using the same, which are provided in embodiments 1 to 4 and which employ non-annealed CsPbBr₃I-V curves of thin film solar cells;

as can be seen from fig. 7, the Power Conversion Efficiency (PCE) of the film after annealing at 300 ℃ is high, but is only 2.37%. Specific parameters of the Perovskite Solar Cells (PSCs) after annealing at different temperatures are shown in Table 1. To further optimize CsPbBr under the conditions₃The device of (2) was optimized for different annealing times at an annealing temperature of 300 c, as shown in fig. 8.

Table 1 shows solar cells and solar cells using non-annealed CsPbBr according to application examples 1 to 4₃Specific parameters of thin film solar cells

FIG. 8 shows a solar cell provided in application example 1 and application examples 5 to 8, and a solar cell using non-annealed CsPbBr₃I-V curves of thin film solar cells;

as can be seen from fig. 8, the Voc of the device did not change much after annealing at 300 ℃ for various times, fluctuating around 1.35V, but when the annealing time was 40min, the voltage dropped to 0.93V. Different from the voltage change situation, Jsc increases and then decreases along with the prolonging of annealing time, and the Jsc of the device is maximum after annealing for 30min and has a value of 5.82mA/cm². The PSCs specific parameters are shown in Table 2. The PCE of the device increases and then decreases with increasing annealing time. After 300 anneals for 30min, the cell achieved 5.93% efficiency.

Table 2 shows the solar cells provided in application example 1 and application examples 5 to 8 and the solar cells using the non-annealed solar cellsCsPbBr of₃Specific parameters of thin-film solar cells (as-prepared)

FIG. 9 shows the annealed CsPbBr samples provided in examples 11 to 14₃Thin films and unannealed CsPbBr in example 11₃X-ray diffraction test pattern of the film (as-prepared);

as can be seen from fig. 9, the orientation and strength were varied under the conditions of different annealing temperatures; the peaks at 15.18 and 30.82 for the unannealed pristine film correspond to CsPbBr₃Orthogonal phase (101) and (202) orientations. When the annealing temperature is 250 ℃, the strength of the crystal directions of the films (101) and (202) is weakened, and the films grow along the (121) crystal direction of 21.58 DEG and the (123) crystal direction of 38.04 deg. When the annealing temperature is further increased, the growth strength along the (121) and (123) crystal directions is weakened, and the thin film is preferentially grown along the (101) and (202) crystal directions again. Meanwhile, when the annealing temperature reaches 350 ℃, the peak intensity reaches the strongest value, the temperature continues to rise, and the characteristic peak intensity is reduced to some extent. And we calculated the full width at half maximum (FWHM) (0.163) of the crystal orientation of this sample (202), which is smaller than 400 ℃ (0.201), indicating that the crystallinity is better at 350 ℃. It was demonstrated that post-annealing temperature has a significant effect on film crystallinity under this experimental condition, and that 350 ℃ annealing temperature crystallinity is the best of all samples.

FIG. 10 shows the annealed CsPbBr samples provided in examples 11 to 14₃Thin films and unannealed CsPbBr in example 11₃Ultraviolet-visible (UV-Vis) transmission spectrum of the film;

as can be seen from FIG. 10, all samples with different annealing temperature conditions exhibited an absorption edge at 520 nm. And it can be observed that the absorption edge strength changes with increasing annealing temperature. Specifically, as the annealing temperature increases, the absorption peak intensity increases and then decreases. When the annealing temperature reaches 350 ℃, the light absorption intensity is highest. This indicates that the enhancement of crystallinity and the enlargement of crystal grains improve the light trapping ability.

FIG. 11 is a drawing for examples 11 to 14Annealed CsPbBr supplied₃Thin films and unannealed CsPbBr in example 11₃Photoluminescence (PL) test spectrum of the thin film;

as can be seen from FIG. 11, the PL peak at 515nm of the original film first decreased in intensity with increasing annealing temperature, and increased significantly at 530nm when the temperature reached 350 ℃. The peak strength of the annealed film indicates that the crystallinity of the annealed film is improved, the grain size is increased, and simultaneously, the non-radiative recombination of defect-assisted photon-generated carriers in the perovskite layer is remarkably inhibited. When the temperature was raised to 400 ℃, the intensity decreased again, which is consistent with XRD and test results.

FIG. 12 shows the annealed CsPbBr samples provided in examples 11 to 14₃Thin films and unannealed CsPbBr in example 11₃Scanning Electron Microscope (SEM) photographs of the thin film;

as can be seen from fig. 12, these perovskite thin films each have a dense pinhole-free morphology, and the grain size is becoming larger as the annealing temperature is increased. When the annealing temperature is 350 ℃, the grain size can reach micron level. As the annealing temperature is further increased, the grain size is further increased. However, as can be seen from the figure, the grain size of the 400 ℃ annealed profile is further increased than that of the 350 ℃ annealed profile, and we speculate that the roughness may be further increased, which will affect the contact of the active layer with other layers, resulting in the degradation of the device performance. In any event, it is concluded from the figure that the annealing temperature does improve the film morphology, increasing the grain size.

FIG. 13 shows solar cells according to embodiments 9-12 and non-annealed CsPbBr₃I-V curves of thin film solar cells;

FIG. 14 shows a solar cell provided in application example 11 and application examples 13 to 17, and a solar cell using non-annealed CsPbBr₃I-V curves of thin film solar cells;

from fig. 13 to 14, the specific photovoltaic parameters are shown in tables 3 and 4. Based on unannealed CsPbBr₃The conversion efficiency of the device prepared by the film is only 0.64 percent, and the short-circuit current is 1.61mA/cm²Open circuit voltage of 0.92V, fillThe factor was 43.26%. The perovskite thin film has small crystal grains and a large number of crystal boundaries, so that a large number of carriers are compounded, and the performance index of a device is reduced. The performance of the device is greatly improved by annealing at 350 ℃. The conversion efficiency is increased to 7.81 percent, the open-circuit voltage is further increased to 1.43V, the filling factor is 79.96 percent, and the short-circuit current is 6.81mA/cm². When the annealing temperature continues to increase to 400 ℃, poor contact between the perovskite active layer and the carbon slurry may result, possibly due to a significant increase in film roughness, resulting in a reduction in open circuit voltage and short circuit current, ultimately resulting in a 7.15% conversion efficiency. We also found that the annealing time only has a weak influence on the device, and the conversion efficiency of the device constructed with different annealing times is above 7% except for the 40min annealed sample.

Table 3 shows the solar cells provided in application examples 9-12 and the solar cells using non-annealed CsPbBr₃Specific parameters of thin film solar cells

Table 4 shows the annealed CsPbBr provided in application example 11 and application examples 13 to 17₃Specific parameters of devices made of thin films

It will be apparent to those skilled in the art that various changes and modifications may be made in the present invention without departing from the spirit and scope of the invention. Thus, it is intended that such changes and modifications be included within the scope of the appended claims and their equivalents.

Claims

1. A method for preparing a perovskite thin film based on a non-solvent is characterized by comprising the following steps:

2. The method for preparing perovskite thin film based on non-solvent as claimed in claim 1, wherein the raw materials are CsBr and PbBr powder₂Mixing is carried out by means of grinding.

3. The non-solvent based process for preparing perovskite thin film according to claim 2, wherein CsBr and PbBr are₂The molar ratio is 1-2: 1.

4. the method for preparing a perovskite thin film on the basis of a non-solvent according to claim 2, wherein the perovskite thin film is CsPbBr₃A film.

5. The non-solvent based process for preparing a perovskite thin film according to claim 1, wherein the evaporation method is an electron beam evaporation method.

6. The method for preparing perovskite thin film based on non-solvent according to claim 5, wherein the evaporation method adopts electron beam evaporation method, and the regulated evaporation beam current is 1-10 mA.

7. The method for non-solvent based production of perovskite thin film according to claim 1, wherein the substrate is treated according to the following steps before use:

8. The method for preparing perovskite thin film based on non-solvent according to claim 7, wherein the substrate is quartz glass substrate or SnO doped with fluorine₂Conductive glass.

9. A perovskite thin film produced by the method as claimed in any one of claims 1 to 8.

10. Use of the perovskite thin film as defined in claim 9 in a solar cell.