Perovskite solar cell with submicroscopic protrusions and preparation method thereof

Abstract

The invention relates to the technical field of perovskite cells, and provides a perovskite solar cell with submicroscopic protrusions and a preparation method thereof.The perovskite solar cell comprises a conductive glass substrate, an electron transport layer, a perovskite active layer, a hole transport layer and a metal electrode which are tightly connected in sequence from top to bottom, the lower surface of the perovskite active layer is provided with a plurality of submicroscopic protrusions with the height ranging from 100 nm to 170 nm, and the interval between every two submicroscopic protrusions ranges from 2.5 micrometers to 7.5 micrometers. When incident light is irradiated on the perovskite solar cell and penetrates through the perovskite active layer, the submicroscopic protrusions enable the incident light to be subjected to back scattering, and the incident light subjected to back scattering is reflected back to the perovskite active layer by the metal electrode. The efficiency of the perovskite solar cell can be effectively improved.

Description

Technical Field

[0001] The present invention relates to the technical field of perovskite cells, and in particular to a perovskite solar cell with submicroscopic protrusions and a preparation method thereof. Background Art

[0002] Solar energy is abundant and inexhaustible, and is recognized as a clean energy source by countries around the world. Solar cells can convert solar energy into electrical energy. Among them, perovskite solar cells are one of the research hotspots in the field of energy photovoltaics, and their photoelectric conversion efficiency is close to that of crystalline silicon solar cells. In recent years, people have used a variety of methods to prepare high-quality perovskite light-absorbing layers to improve device efficiency, such as additive engineering, solvent engineering, and designing new charge transport materials. Although these methods improve the crystallinity and film quality of perovskites, it is difficult to adjust the surface morphology of the perovskite light-absorbing layer. In addition, the theoretical maximum short-circuit current density of perovskite solar cells has not yet reached the Shockley-Queisser limit, because a considerable part of the incident light becomes loss instead of being converted into electrical energy. Specifically, the perovskite light-absorbing layer prepared by the solution method usually exhibits a relatively flat surface due to its process characteristics, which causes a part of the incident light to directly pass through the perovskite light-absorbing layer and will not be used by the perovskite light-absorbing layer. Moreover, perovskite solar cells are multilayer structures with interfaces between the layers. Poor interface contact is also not conducive to the collection and transmission of carriers. The microscopic morphology of perovskite films determines their absorption, transmission and reflection of light, thus affecting the density of photogenerated carriers. In the prior art, the surface of perovskites is mostly flat, which does not absorb enough light, resulting in low density of photogenerated carriers and reducing device efficiency. Summary of the invention

[0003] The present invention aims to solve at least one of the technical problems existing in the related art. To this end, the present invention provides a perovskite solar cell with submicroscopic protrusions and a preparation method thereof, so as to realize the production of a perovskite cell with high light energy utilization rate.

[0004] The present invention provides a perovskite solar cell with submicroscopic protrusions, comprising a conductive glass substrate, an electron transport layer, a perovskite active layer, a hole transport layer and a metal electrode which are closely connected in sequence from top to bottom, wherein the lower surface of the perovskite active layer has a plurality of submicroscopic protrusions with a height of 100 nm to 170 nm, and the intervals between the submicroscopic protrusions are 2.5 μm to 7.5 μm; When incident light shines on the perovskite solar cell and passes through the perovskite active layer, the submicroscopic protrusions cause the incident light to be backscattered, and the backscattered incident light is reflected back to the perovskite active layer by the metal electrode.

[0005] According to the perovskite solar cell with submicroscopic protrusions provided by the present invention, the height of the submicroscopic protrusions on the lower surface of the perovskite active layer is 120 nm, and the interval between the submicroscopic protrusions is 3.8 μm.

[0006] According to the perovskite solar cell with submicroscopic protrusions provided by the present invention, the conductive glass substrate is ITO conductive glass, the metal electrode is a silver electrode, the electron transport layer is tin oxide, and the hole transport layer is a first compound doped with lithium bis(trifluoromethanesulfonyl)imide and tert-butylpyridine, and the structural formula of the first compound is as follows: .

[0007] According to the perovskite solar cell with submicroscopic protrusions provided by the present invention, the thickness of the metal electrode is 50nm~150nm.

[0008] The present invention provides a method for preparing a perovskite solar cell having submicroscopic protrusions, comprising the following steps: S1: Clean, blow dry and treat the conductive glass substrate with UV ozone; S2: obtaining an electron transport layer solution, spin-coating the electron transport layer solution on a conductive glass substrate, and performing a first annealing treatment on the spin-coated electron transport layer solution to obtain a first substrate to be treated; S3: obtaining a perovskite precursor solution, an anti-solvent and a first solution, dissolving the perovskite precursor solution in the first solution, and adding a perovskite additive to the perovskite precursor solution to obtain a target precursor solution, wherein the perovskite additive includes a second compound having a molar fraction of 5% to 20%, spin-coating the precursor solution on the first substrate to be processed and adding an anti-solvent, performing a second annealing treatment on the first substrate to be processed after spin coating, and obtaining a second substrate to be processed, wherein the structural formula of the second compound is as follows: ; S4: spin-coating a solution of the first compound on the second substrate to be processed to obtain a third substrate to be processed, selecting an electrode metal, and vapor-depositing the electrode metal on the third substrate to be processed to obtain a perovskite solar cell with submicroscopic protrusions, wherein the solution of the first compound includes lithium bis(trifluoromethanesulfonyl)imide and tert-butylpyridine.

[0009] According to the method for preparing a perovskite solar cell with submicroscopic protrusions provided by the present invention, in step S2, the electron transport layer solution is a tin oxide colloidal aqueous solution with a mass fraction of 3% to 5%, the duration of the first annealing treatment is 20 minutes to 60 minutes, and the annealing temperature is 90°C to 180°C.

[0010] According to the method for preparing a perovskite solar cell with submicroscopic protrusions provided by the present invention, in step S3, the perovskite precursor solution includes cesium iodide, lead iodide, lead bromide and formamidine iodide, and the molar concentration of the lead element in the perovskite precursor solution is 1.0 mol / L~1.6 mol / L.

[0011] According to the method for preparing a perovskite solar cell with submicroscopic protrusions provided by the present invention, in step S3, the first solution includes N,N-dimethylformamide and dimethyl sulfoxide, and the volume ratio of N,N-dimethylformamide and dimethyl sulfoxide is 2:1 to 5:1, and when the anti-solvent is added, the volume ratio of the target precursor solution and the anti-solvent is 0.35:1 to 0.035:1.

[0012] According to the method for preparing a perovskite solar cell with submicroscopic protrusions provided by the present invention, in step S3, the perovskite additive includes a second compound with a molar fraction of 10%.

[0013] According to the method for preparing a perovskite solar cell with submicroscopic protrusions provided by the present invention, in step S3, the duration of the second annealing treatment is 5 minutes to 60 minutes, and the annealing temperature is 90° C. to 150° C.

[0014] The above one or more technical solutions in the embodiments of the present invention have at least one of the following technical effects: The perovskite solar cell with submicroscopic protrusions provided by the present invention and the preparation method thereof, through the submicroscopic protrusions on the lower surface of the perovskite active layer, the incident light passing through the perovskite active layer is backscattered, so that it is re-reflected back into the perovskite active layer by the metal electrode, thereby improving the utilization efficiency of the perovskite solar cell for light energy. In addition, the submicroscopic protrusions also increase the contact area between the perovskite active layer and the hole transport layer, which is beneficial to the separation and extraction of charges, and improves the efficiency of the perovskite solar cell.

[0015] Additional aspects and advantages of the present invention will be given in part in the following description and in part will be obvious from the following description, or will be learned through practice of the present invention. BRIEF DESCRIPTION OF THE DRAWINGS

[0016] In order to more clearly illustrate the technical solutions in the present invention or the prior art, the drawings required for use in the embodiments or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative work.

[0017] Figure 1 It is a schematic diagram of the structure of a perovskite solar cell with submicroscopic protrusions provided by the present invention.

[0018] Figure 2 It is a comparison diagram of the lower surface morphology of a perovskite solar cell with submicroscopic protrusions provided by the present invention and a perovskite solar cell without using a perovskite additive including a second compound.

[0019] Figure 3 It is an ultraviolet-visible absorption spectrum diagram of the perovskite solar cell provided by the present invention and the perovskite solar cell without using the perovskite additive including the second compound.

[0020] Figure 4 3 is a current density-voltage curve diagram of the perovskite solar cell provided by the present invention and the perovskite solar cell without using the perovskite additive including the second compound.

[0021] Figure 5 It is a schematic diagram of a cross-section of a perovskite active layer of a perovskite solar cell provided by the present invention.

[0022] Figure 6 It is an X-ray diffraction diagram of the perovskite active layer of the perovskite solar cell provided by the present invention at different molar fractions of the second compound.

[0023] Reference numerals: 1. Conductive glass substrate; 2. Electron transport layer; 3. Perovskite active layer; 4. Hole transport layer; 5. Metal electrode. DETAILED DESCRIPTION

[0024] In order to make the purpose, technical scheme and advantages of the present invention clearer, the technical scheme in the present invention will be clearly and completely described below. Obviously, the described embodiments are part of the embodiments of the present invention, rather than all the embodiments. Based on the embodiments in the present invention, all other embodiments obtained by ordinary technicians in the field without creative work are within the scope of protection of the present invention. The following embodiments are used to illustrate the present invention, but cannot be used to limit the scope of the present invention.

[0025] In the description of the embodiments of the present invention, it should be noted that the terms "center", "longitudinal", "lateral", "up", "down", "front", "back", "left", "right", "vertical", "horizontal", "top", "bottom", "inside", "outside" and the like indicate positions or positional relationships based on the positions or positional relationships shown in the accompanying drawings, and are only for the convenience of describing the embodiments of the present invention and simplifying the description, and do not indicate or imply that the devices or elements referred to must have a specific orientation, be constructed and operate in a specific orientation, and therefore cannot be understood as limitations on the embodiments of the present invention. In addition, the terms "first", "second", and "third" are used for descriptive purposes only and cannot be understood as indicating or implying relative importance.

[0026] In the description of the embodiments of the present invention, it should be noted that, unless otherwise clearly specified and limited, the terms "connected" and "connection" should be understood in a broad sense, for example, it can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection or an electrical connection; it can be a direct connection or an indirect connection through an intermediate medium. For ordinary technicians in this field, the specific meanings of the above terms in the embodiments of the present invention can be understood according to specific circumstances.

[0027] In the embodiments of the present invention, unless otherwise clearly specified and limited, the first feature being "above" or "below" the second feature may mean that the first and second features are in direct contact, or the first and second features are in indirect contact through an intermediate medium. Moreover, the first feature being "above", "above" and "above" the second feature may mean that the first feature is directly above or obliquely above the second feature, or simply means that the first feature is higher in level than the second feature. The first feature being "below", "below" and "below" the second feature may mean that the first feature is directly below or obliquely below the second feature, or simply means that the first feature is lower in level than the second feature.

[0028] In the description of this specification, the description with reference to the terms "one embodiment", "some embodiments", "example", "specific example", or "some examples" etc. means that the specific features, structures, materials or characteristics described in conjunction with the embodiment or example are included in at least one embodiment or example of the embodiment of the present invention. In this specification, the schematic representations of the above terms do not necessarily refer to the same embodiment or example. Moreover, the specific features, structures, materials or characteristics described may be combined in any one or more embodiments or examples in a suitable manner. In addition, those skilled in the art may combine and combine the different embodiments or examples described in this specification and the features of the different embodiments or examples, without contradiction.

[0029] Combine the following Figures 1 to 6 Describe the specific embodiments of the present invention: Embodiment 1: The preparation method of the perovskite solar cell with submicroscopic protrusions is as follows: First, a conductive glass substrate 1 is selected. In this embodiment, the conductive glass substrate 1 is ITO (Indium tin oxide) conductive glass. Then, the conductive glass substrate 1 is ultrasonically cleaned using an ultrasonic cleaning device, and after ultrasonic cleaning, it is blown dry using nitrogen to complete the cleaning and drying of the conductive glass substrate 1. Then, the conductive glass substrate 1 is subjected to ultraviolet ozone treatment using an ultraviolet ozone cleaning machine. The ultraviolet ozone cleaning machine removes grease and organic matter on the surface of the conductive glass substrate 1 by oxidation through ultraviolet light and ozone, making the surface cleaner.

[0030] Then obtain the electron transport layer solution, which is a 3% to 5% mass fraction of tin oxide colloidal aqueous solution, and preferably a 3.75% mass fraction of tin oxide colloidal aqueous solution in this embodiment. Then place the conductive glass substrate 1 on a spin coater and drop the electron transport layer solution on the conductive glass substrate. Here, the amount of the electron transport layer solution added is 40 μL to 200 μL, and preferably 100 μL in this embodiment. Start the spin coater, the spin coater rotates at high speed and uses centrifugal acceleration to quickly spread the solution, and the excess solution will be thrown off the conductive glass substrate 1 by the spin coater. The spin coater works at a speed of 4000 revolutions per minute for 30 seconds, so that the electron transport layer solution is evenly spin-coated on the conductive glass substrate 1. The electron transport layer solution after spin coating is subjected to a first annealing treatment. The annealing temperature of the first annealing treatment is 90°C to 180°C, preferably 150°C in this embodiment, and the duration of the first annealing treatment is 20 minutes to 60 minutes, preferably 30 minutes in this embodiment, thereby preparing an electron transport layer 2 on the conductive glass substrate 1 to obtain a first substrate to be treated.

[0031] Then, a perovskite precursor solution is obtained, wherein the perovskite precursor solution includes cesium iodide, lead iodide, lead bromide, lead chloride and formamidine iodide, and the molar concentration of the lead element in the perovskite precursor solution is 1.0 mol / L~1.6 mol / L. In the present embodiment, it is preferably 1.377 mol / L, wherein the molar concentration of cesium iodide is 0.405 mol / L, the molar concentration of lead bromide is 0.405 mol / L, the molar concentration of formamidine iodide is 0.81 mol / L, the molar concentration of lead iodide is 0.945 mol / L, and there is also lead chloride, whose molar concentration is 0.027 mol / L. The perovskite precursor solution is dissolved in the first solution, the first solution includes N,N-dimethylformamide and dimethyl sulfoxide, and the volume ratio of N,N-dimethylformamide and dimethyl sulfoxide is 2:1 to 5:1. In the present embodiment, the volume ratio of N,N-dimethylformamide and dimethyl sulfoxide is preferably 4:1.

[0032] In addition, a perovskite additive having a molar fraction of 5% to 20% of a second compound is added to the perovskite precursor solution. The name of the second compound is dimethylamine hydroiodide, and its structural formula is as follows: , In the present embodiment, the molar fraction of the second compound is preferably 10%. After adding the second compound, the target precursor solution can be obtained, and the target precursor solution is spin-coated on the electron transport layer 2 of the first substrate to be processed and an anti-solvent is added. When the anti-solvent is added, the volume ratio of the target precursor solution and the anti-solvent is 0.35: 1 to 0.035: 1, and the specific ratio needs to be determined according to the type of anti-solvent. Here, the anti-solvent is a low-polarity solvent, which can be ethyl acetate, chlorobenzene, anisole, ether, etc., preferably chlorobenzene in the present embodiment, and the volume of the target precursor solution spin-coated on the first substrate to be processed in the present embodiment is 35 μL, and the spin coating is spun at a speed of 6000 revolutions per minute for 30 seconds. The first substrate to be processed after spin coating is subjected to a second annealing treatment, and the duration of the second annealing treatment is 5 minutes to 60 minutes, and the annealing temperature is 90°C to 150°C. In this embodiment, the annealing time is preferably 30 minutes, and the annealing temperature is preferably 100° C. After the second annealing treatment is completed, the perovskite active layer 3 is prepared on the first substrate to be treated, thereby obtaining the second substrate to be treated.

[0033] Then, the solution of the first compound is spin-coated on the perovskite active layer 3 of the second substrate to be processed to obtain a third substrate to be processed. The structural formula of the first compound is shown below: , The name of the first compound is 2,2',7,7'-tetra[N,N-di(4-methoxyphenyl)amino]-9,9'-spirobifluorene. In this embodiment, the solution of the first compound is a chlorobenzene solution of the first compound. In addition, the solution of the first compound also contains a small amount of lithium bis(trifluoromethanesulfonyl)imide and a small amount of tert-butylpyridine. In this embodiment, lithium bis(trifluoromethanesulfonyl)imide is 17.5 μL of chlorobenzene solution of lithium bis(trifluoromethanesulfonyl)imide, and tert-butylpyridine is 28.5 μL of chlorobenzene solution of tert-butylpyridine. The concentrations of the chlorobenzene solution of lithium bis(trifluoromethanesulfonyl)imide and the chlorobenzene solution of tert-butylpyridine are both 520 mg / ml. Finally, an electrode metal is selected. The electrode metal can be gold or silver. In this embodiment, the electrode metal selected is silver. The electrode metal is vacuum-evaporated on the solution of the first compound after spin coating on the third substrate to be treated through a vacuum coating system to obtain a hole transport layer 4 and a metal electrode 5, wherein the thickness of the metal electrode 5 is 50nm~150nm. And the prepared hole transport layer 4 is a first compound doped with lithium bis(trifluoromethanesulfonyl)imide and tert-butylpyridine. In this way, a perovskite solar cell with submicroscopic protrusions is obtained. The incident light is incident from the conductive glass substrate 1, and passes through the electron transport layer 2, the perovskite active layer 3, the hole transport layer 4 and the metal electrode 5 in sequence. Taking the incident position of the incident light as the starting point, the conductive glass substrate 1, the electron transport layer 2, the perovskite active layer 3, the hole transport layer 4 and the metal electrode 5 are tightly connected in sequence from top to bottom, Figure 1Schematic diagram of the structure of the prepared perovskite solar cell with submicroscopic protrusions.

[0034] The lower surface of the perovskite active layer 3 of the perovskite solar cell with submicroscopic protrusions prepared in this embodiment has a plurality of submicroscopic protrusions with a height of 120 nm, and the interval between two submicroscopic protrusions is 3.8 μm. Here, the lower surface refers to the surface where the perovskite active layer 3 is connected to the hole transport layer 4. The lower surface morphology of the perovskite active layer 3 of the perovskite solar cell in this embodiment is as follows: Figure 2 (b) shows that the perovskite additive without the second compound is Figure 2 Compared with the perovskite active layer 3 presented in (a), the perovskite additive including the second compound can make the lower surface of the perovskite active layer 3 have an obvious submicroscopic protrusion structure, and this submicroscopic protrusion structure can act as a diffraction grating, so that after the incident light enters the perovskite active layer 3 from the side of the electron transport layer 3, most of it will be absorbed, but a part of the incident light will still pass through the perovskite active layer 3. At this time, due to the role of the submicroscopic protrusion as a diffraction grating, this part of the incident light will be backscattered, thereby being reflected by the metal electrode 5 and re-entering the perovskite active layer 3 for use. In addition, the submicroscopic protrusions also increase the contact area between the perovskite active layer 3 and the hole transport layer 4, thereby optimizing the contact of the interface heterojunction, facilitating the separation and extraction of charges, and further improving the efficiency of the perovskite solar cell.

[0035] Table 1 is a performance comparison of a perovskite solar cell that does not use a perovskite additive including a second compound and a perovskite solar cell provided in this embodiment, wherein Voc is the open circuit voltage, which refers to the potential difference across the circuit when the current in the circuit where the battery device is located is zero or the external load impedance is infinite, Jsc is the ratio of the current in the circuit to the unit cross-sectional area when the voltage in the circuit where the battery device is located is zero or the external load is infinite, FF is the ratio of the maximum output power of the battery device to the product of the short-circuit current and the open-circuit voltage, and PCE is the ratio of the maximum output power of the battery device to the incident light power. The larger these values ​​are, the better the battery performance is.

[0036] Table 1 Performance comparison between a perovskite solar cell without using a perovskite additive including the second compound and the perovskite solar cell provided in this embodiment

[0037] Figure 3 ] is a UV-visible absorption spectrum of a perovskite solar cell that does not use the perovskite additive including the second compound and a perovskite solar cell provided in this embodiment, where au is an absorbance unit, Figure 4The current density-voltage curves of the perovskite solar cell without the perovskite additive including the second compound and the perovskite solar cell provided in this embodiment at different voltages. Figure 3 and Figure 4 In the figure, A represents a perovskite solar cell that does not use the perovskite additive including the second compound, and B represents the perovskite solar cell provided in this embodiment. It can be seen that the performance of the perovskite solar cell provided in this embodiment has been significantly improved.

[0038] In order to describe the morphology of submicroscopic protrusions, the cross-section of the submicroscopic protrusion structure can be regarded as a curve similar to a sine function. The height H of the submicroscopic protrusion and the distance λ between the tops of two submicroscopic protrusions can be measured by atomic force microscopy, scanning electron microscopy and other characterization methods. Here, the height H of the submicroscopic protrusion and the distance λ between the tops of two submicroscopic protrusions are the average values ​​of the heights and distances of multiple submicroscopic protrusions. Figure 5 Schematic diagram of the cross-section of the perovskite active layer. The values ​​of H and λ can be changed by changing the concentration of the second compound in the perovskite additive, the concentration of the lead element in the perovskite precursor solution, the volume ratio of N,N-dimethylformamide and dimethyl sulfoxide in the first solution, and the annealing time of the second annealing treatment. Here, based on the preparation method of the perovskite solar cell with submicroscopic protrusions described above in this embodiment, the concentration of the second compound in the perovskite additive, the concentration of the perovskite precursor solution, the volume ratio of N,N-dimethylformamide and dimethyl sulfoxide in the first solution, and the annealing time of the second annealing treatment are changed respectively, wherein the molar fraction of the second compound increases by 5% each time from 5% to 20%, the concentration of the lead element in the perovskite precursor solution increases by 0.2 mol / L each time, the volume ratio of N,N-dimethylformamide and dimethyl sulfoxide in the first solution is 2:1, 3:1, 4:1 and 5:1 respectively, and the annealing time of the second annealing treatment is 5 minutes, 20 minutes, 45 minutes and 60 minutes respectively. Table 2 shows the range of λ and H under different preparation conditions.

[0039] Table 2 Schematic diagram of the range of λ and H under different preparation conditions

[0040] Here, the higher the molar fraction of the second compound and the concentration of the lead element in the perovskite precursor solution, the greater the increase in λ and H; the greater the volume ratio of N,N-dimethylformamide and dimethyl sulfoxide in the first solution, the greater the increase in λ and the less the H; the greater the annealing time of the second annealing treatment, the less the λ and the less the H.

[0041] It can be seen that the height of the submicroscopic protrusions is between 70nm and 230nm, and the interval between two submicroscopic protrusions is 2.0μm to 7.5μm. Among them, the interval between the two submicroscopic protrusions has a greater impact on the performance of the perovskite solar cell, and the effect of changing the molar fraction of the second compound in the perovskite additive on the regulation of λ and H is more obvious, especially for λ. In the actual preparation process, the molar fraction of the second compound is also easier to regulate, and has little effect on other aspects of the performance of the perovskite solar cell. Therefore, the high-performance perovskite solar cell is prepared mainly by changing the molar fraction of the second compound in the perovskite additive.

[0042] Embodiment 2: The preparation method of the perovskite solar cell with submicroscopic protrusions is as follows: First, a conductive glass substrate 1 is selected. In this embodiment, the conductive glass substrate 1 is an ITO conductive glass. Then, the conductive glass substrate 1 is ultrasonically cleaned using an ultrasonic cleaning device, and after ultrasonic cleaning, it is blown dry using nitrogen, thereby completing the cleaning and drying of the conductive glass substrate 1. Then, a UV ozone cleaning machine is used to perform UV ozone treatment on the conductive glass substrate 1. The UV ozone cleaning machine removes grease and organic matter on the surface of the conductive glass substrate 1 by oxidation through UV light and ozone, making the surface cleaner.

[0043] Then obtain an electron transport layer solution, which is a 3% to 5% mass fraction tin oxide colloidal aqueous solution, and in this embodiment, preferably a 3.75% mass fraction tin oxide colloidal aqueous solution. Then place the conductive glass substrate 1 on a spin coater and drop the electron transport layer solution on the conductive glass substrate, where the amount of the electron transport layer solution added is 40 μL to 200 μL, and in this embodiment, preferably 100 μL. Start the spin coater, and the spin coater works at a speed of 4000 revolutions per minute for 30 seconds, so that the electron transport layer solution is evenly spin-coated on the conductive glass substrate 1. The electron transport layer solution after spin coating is subjected to a first annealing treatment. The annealing temperature of the first annealing treatment is 90°C to 180°C, and in this embodiment, preferably 150°C, and the duration of the first annealing treatment is 20 minutes to 60 minutes, and in this embodiment, preferably 30 minutes, thereby preparing an electron transport layer 2 on the conductive glass substrate 1 to obtain a first substrate to be treated.

[0044] Then, a perovskite precursor solution is obtained, wherein the perovskite precursor solution includes cesium iodide, lead iodide, lead bromide, lead chloride and formamidine iodide, and the molar concentration of the lead element in the perovskite precursor solution is 1.0 mol / L~1.6 mol / L. In the present embodiment, it is preferably 1.377 mol / L, wherein the molar concentration of cesium iodide is 0.405 mol / L, the molar concentration of lead bromide is 0.405 mol / L, the molar concentration of formamidine iodide is 0.81 mol / L, the molar concentration of lead iodide is 0.945 mol / L, and there is also lead chloride, whose molar concentration is 0.027 mol / L. The perovskite precursor solution is dissolved in the first solution, the first solution includes N,N-dimethylformamide and dimethyl sulfoxide, and the volume ratio of N,N-dimethylformamide and dimethyl sulfoxide is 2:1 to 5:1. In the present embodiment, the volume ratio of N,N-dimethylformamide and dimethyl sulfoxide is preferably 4:1.

[0045] In addition, a perovskite additive having a molar fraction of 0% to 20% of a second compound is added to the perovskite precursor solution. The name of the second compound is dimethylamine hydroiodide, and its structural formula is as follows: , In the present embodiment, the molar fractions of the second compound are 0%, 5%, 10%, and 15% respectively. 20%, these second compounds with different molar fractions are added to the perovskite precursor solution respectively, and different target precursor solutions are respectively spin-coated on the electron transport layer 2 of the first substrate to be processed and an anti-solvent is added. When the anti-solvent is added, the volume ratio of the target precursor solution and the anti-solvent is 0.35: 1 to 0.035: 1, and the specific ratio needs to be determined according to the type of anti-solvent. Here, the anti-solvent is a low-polarity solvent, which can be ethyl acetate, chlorobenzene, anisole, ether, etc., preferably chlorobenzene in the present embodiment, and the volume of the target precursor solution spin-coated on each first substrate to be processed in the present embodiment is 35 μL, and the spin coating is spun at a speed of 6000 revolutions per minute for 30 seconds. Each first substrate to be processed after spin coating is subjected to a second annealing treatment, and the duration of the second annealing treatment is 5 minutes to 60 minutes, and the annealing temperature is 90°C to 150°C. In this embodiment, the annealing time is preferably 30 minutes, and the annealing temperature is preferably 100° C. After the second annealing treatment is completed, a perovskite active layer 3 is prepared on each first substrate to be processed, thereby obtaining a plurality of second substrates to be processed.

[0046] Then, the solution of the first compound is spin-coated on the perovskite active layer 3 of each second substrate to be processed to obtain a third substrate to be processed. The structural formula of the first compound is shown below: , The name of the first compound is 2,2',7,7'-tetra[N,N-di(4-methoxyphenyl)amino]-9,9'-spirobifluorene. In this embodiment, the solution of the first compound is a chlorobenzene solution of the first compound. In addition, the solution of the first compound also contains a small amount of lithium bis(trifluoromethanesulfonyl)imide and a small amount of tert-butylpyridine. In this embodiment, lithium bis(trifluoromethanesulfonyl)imide is 17.5 μL of chlorobenzene solution of lithium bis(trifluoromethanesulfonyl)imide, and tert-butylpyridine is 28.5 μL of chlorobenzene solution of tert-butylpyridine. The concentrations of the chlorobenzene solution of lithium bis(trifluoromethanesulfonyl)imide and the chlorobenzene solution of tert-butylpyridine are both 520 mg / ml. Finally, an electrode metal is selected. The electrode metal can be gold or silver. In this embodiment, the electrode metal selected is silver. The electrode metal is vacuum-evaporated on the solution of the first compound after spin coating of each third substrate to be treated by a vacuum coating system to obtain a hole transport layer 4 and a metal electrode 5, wherein the thickness of the metal electrode 5 is 50nm~150nm. And the prepared hole transport layer 4 is a first compound doped with lithium bis(trifluoromethanesulfonyl)imide and tert-butylpyridine. In this way, a plurality of perovskite solar cells with submicroscopic protrusions are obtained. The incident light is incident from the conductive glass substrate 1, and passes through the electron transport layer 2, the perovskite active layer 3, the hole transport layer 4 and the metal electrode 5 in sequence. Taking the incident position of the incident light as the starting point, the conductive glass substrate 1, the electron transport layer 2, the perovskite active layer 3, the hole transport layer 4 and the metal electrode 5 are tightly connected from top to bottom.

[0047] Due to the different concentrations of the second compound, the heights and intervals of the submicroscopic protrusions on the lower surface of the perovskite active layer 3 of the obtained perovskite solar cell are also different. Here, the lower surface refers to the surface where the perovskite active layer 3 is connected to the hole transport layer 4. The heights and intervals of the submicroscopic protrusions on the lower surface of the perovskite active layer under different molar fractions of the second compound are shown in Table 3: Table 3 Schematic diagram of the height and spacing of submicroscopic protrusions on the lower surface of the perovskite active layer at different molar fractions of the second compound

[0048] It can be seen that as the molar fraction of the second compound increases, the height and spacing of the submicroscopic protrusions increase. However, since the purpose of the perovskite active layer is to convert light energy into electrical energy, the crystal quality and phase purity of the perovskite active layer also need to be considered. The impurity phase will reduce the light absorption capacity of the perovskite active layer, so only the morphology of the submicroscopic protrusions cannot be considered. In the present invention, while controlling the morphology of the submicroscopic protrusions, it is necessary to increase the photoactive phase of the perovskite active layer as much as possible, that is, the black phase formamidine lead iodine, and reduce the non-photoactive phase, that is, dimethylamine lead iodine, wide-bandgap yellow non-perovskite phase and lead iodide. Figure 6: The X-ray diffraction diagram of the perovskite active layer at different molar fractions of the second compound, where C is the diffraction peak of dimethylamine lead iodine and the wide-bandgap yellow non-perovskite phase, D is the diffraction peak of lead iodide, and E is the diffraction peak of the black phase formamidine lead iodine. Figure 6 As shown, when the molar fraction of the second compound is 0, there is a large amount of lead iodide in the perovskite active layer, which acts as an impurity phase to reduce the light absorption capacity of the perovskite. When the molar fraction of the second compound is 5%, the lead iodide content begins to decrease. When the molar fraction of the second compound is 10%, the lead iodide content is further reduced, and the content of black phase formamidine lead iodine is also high. Continuing to increase the molar fraction of the second compound, when the molar fraction of the second compound is 15-20%, dimethylamine lead iodine and a wide-bandgap yellow non-perovskite phase are produced, which will reduce the light absorption capacity of the perovskite active layer, thereby reducing the photoelectric conversion efficiency of the perovskite solar cell. Therefore, when the molar fraction of the second compound is 10%, the photoelectric conversion efficiency of the perovskite solar cell is higher.

[0049] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, rather than to limit it. Although the present invention has been described in detail with reference to the aforementioned embodiments, those skilled in the art should understand that they can still modify the technical solutions described in the aforementioned embodiments, or make equivalent replacements for some of the technical features therein. However, these modifications or replacements do not deviate the essence of the corresponding technical solutions from the spirit and scope of the technical solutions of the embodiments of the present invention.

Claims

1. A perovskite solar cell having submicroscopic protrusions, characterized in that The invention comprises a conductive glass substrate, an electron transport layer, a perovskite active layer, a hole transport layer and a metal electrode which are closely connected in sequence from top to bottom, wherein the lower surface of the perovskite active layer has a plurality of submicroscopic protrusions with a height of 100 nm to 170 nm, and the intervals between the submicroscopic protrusions are 2.5 μm to 7.5 μm; When incident light shines on the perovskite solar cell and passes through the perovskite active layer, the submicroscopic protrusions cause the incident light to be backscattered, and the backscattered incident light is reflected back to the perovskite active layer by the metal electrode.

2. The perovskite solar cell with submicroscopic protrusions according to claim 1, characterized in that: The height of the submicroscopic protrusions on the lower surface of the perovskite active layer is 120 nm, and the interval between the submicroscopic protrusions is 3.8 μm.

3. The perovskite solar cell with submicroscopic protrusions according to claim 1, characterized in that: The conductive glass substrate is ITO conductive glass, the metal electrode is a silver electrode, the electron transport layer is tin oxide, and the hole transport layer is a first compound doped with lithium bis(trifluoromethanesulfonyl)imide and tert-butylpyridine. The structural formula of the first compound is as follows: 。 4. The perovskite solar cell with submicroscopic protrusions according to claim 1, characterized in that: The thickness of the metal electrode is 50nm~150nm.

5. A method for preparing a perovskite solar cell having submicroscopic protrusions, characterized in that: The method for preparing a perovskite solar cell having submicroscopic protrusions as claimed in any one of claims 1 to 4 comprises the following steps: S1: Clean, blow dry and treat the conductive glass substrate with UV ozone; S2: obtaining an electron transport layer solution, spin-coating the electron transport layer solution on a conductive glass substrate, and performing a first annealing treatment on the spin-coated electron transport layer solution to obtain a first substrate to be treated; S3: obtaining a perovskite precursor solution, an anti-solvent and a first solution, dissolving the perovskite precursor solution in the first solution, and adding a perovskite additive to the perovskite precursor solution to obtain a target precursor solution, wherein the perovskite additive includes a second compound with a molar fraction of 5% to 20%, spin-coating the target precursor solution on the first substrate to be processed and adding an anti-solvent, performing a second annealing treatment on the first substrate to be processed after spin coating, and obtaining a second substrate to be processed, wherein the structural formula of the second compound is as follows: ； S4: spin-coating a solution of the first compound on the second substrate to be processed to obtain a third substrate to be processed, selecting an electrode metal, and vapor-depositing the electrode metal on the third substrate to be processed to obtain a perovskite solar cell with submicroscopic protrusions, wherein the solution of the first compound includes lithium bis(trifluoromethanesulfonyl)imide and tert-butylpyridine.

6. The method for preparing a perovskite solar cell having submicroscopic protrusions according to claim 5, characterized in that: In step S2, the electron transport layer solution is a 3% to 5% mass fraction tin oxide colloidal aqueous solution, the first annealing treatment lasts for 20 minutes to 60 minutes, and the annealing temperature is 90°C to 180°C.

7. The method for preparing a perovskite solar cell having submicroscopic protrusions according to claim 5, characterized in that: In step S3, the perovskite precursor solution includes cesium iodide, lead iodide, lead bromide and formamidine iodide, and the molar concentration of the lead element in the perovskite precursor solution is 1.0 mol / L~1.6 mol / L.

8. The method for preparing a perovskite solar cell having submicroscopic protrusions according to claim 5, characterized in that: In step S3, the first solution includes N,N-dimethylformamide and dimethyl sulfoxide, and the volume ratio of N,N-dimethylformamide to dimethyl sulfoxide is 2:1 to 5:

1. When the anti-solvent is added, the volume ratio of the target precursor solution to the anti-solvent is 0.35:1 to 0.035:

1.

9. The method for preparing a perovskite solar cell having submicroscopic protrusions according to claim 5, characterized in that: In step S3, the perovskite additive includes a second compound with a molar fraction of 10%.

10. The method for preparing a perovskite solar cell having submicroscopic protrusions according to claim 5, characterized in that: In step S3, the duration of the second annealing treatment is 5 minutes to 60 minutes, and the annealing temperature is 90° C. to 150° C.

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