Method for manufacturing perovskite solar cells and perovskite solar cells with improved interfacial energy matching manufactured by this method.

Abstract

The present invention relates to a method for treating the interface of a perovskite layer for improving the performance of a perovskite solar cell, and to a perovskite solar cell treated by this method. More specifically, the present invention relates to a method for treating the interface of a perovskite layer for improving the performance of a perovskite solar cell, which removes surface defects in the perovskite layer while simultaneously improving energy compatibility with the electron transport layer and preventing performance degradation of the solar cell.

Description

[Technical Field]

[0001] The present invention relates to a method for treating the interface of a perovskite layer for improving the performance of a perovskite solar cell, and to a perovskite solar cell treated by this method. More specifically, the present invention relates to a method for treating the interface of a perovskite layer for improving the performance of a perovskite solar cell, which removes surface defects in the perovskite layer while simultaneously improving energy compatibility with the electron transport layer and preventing performance degradation of the solar cell. [Background technology]

[0002] Perovskite materials with the chemical formula ABX3 (most commonly lead-containing and inorganic lead-halide perovskite materials) are being actively applied to solar cells, achieving a single-element efficiency of 25.2%. It is expected that they will soon reach 30%, the theoretical maximum solar cell efficiency considering light absorption efficiency and charge transfer characteristics. This efficiency is close to the highest efficiency of single-crystal silicon solar cells (26.6%) and is higher than the efficiencies of other polycrystalline silicon solar cells (22.3%) and CdTe solar cells (22.1%), indicating potential for practical application.

[0003] The driving principle of perovskite solar cells involves the generation of photoexcited charges after light absorption, followed by separation of electrons and holes due to the internal potential of the element. These then diffuse to the electrodes and are finally collected. While this driving method works efficiently when an ideal energy structure is formed, defects exist within the perovskite inside the element being driven, causing charge recombination and resulting in a decrease in electromotive force.

[0004] Related recombination principles include Schockley-Read-Hall (SRH) recombination (recombination due to traps present in the bulk), Auger recombination (recombination due to the generation of a large amount of charge), and interfacial recombination (recombination due to shifted energy levels, surface defects, etc.). Through such charge recombination, photoexcited charges lose energy not in the form of light, but in the form of heat, etc. Furthermore, the recombination behavior induces separation of the Quasi-Fermi energy levels, and the open-circuit voltage (V) OC ) reduces.

[0005] To prevent the degradation of perovskite, various control processes are necessary to remove defects. By mixing a defect control material into the perovskite precursor solution, defects can be stabilized during the formation of polycrystalline thin films, while simultaneously regulating the perovskite crystal growth behavior, thereby creating films with significantly controlled grain sizes. Alternatively, the defect control material can be covered over a pre-fabricated perovskite or prepared on a substrate beforehand and used as a crystal composition layer, enabling defect control and crystal growth control of the perovskite.

[0006] Conventional perovskite surface treatment techniques improve perovskite thin films by applying an organic substance containing an A-site material (the element corresponding to A in ABX3) that enables 2D formation of perovskites having an ABX3 chemical structure, or a carboxyl group, phosphate group, or ammonium ion that can bind to and remove anionic or cationic defects on the perovskite surface.

[0007] Conventional perovskite surface treatment techniques, depending on the properties of the material being coated, result in mismatches in energy levels with the electron transport layer stacked on top, affecting the current (J) of the solar cell. SC This has the problem of reducing the fill factor and decreasing the efficiency of the solar cell, and this decrease in efficiency is most pronounced in PIN-structured solar cells.

[0008] Therefore, there is a need to develop a method that can eliminate surface defects while improving the mismatch in energy level alignment between the surface of the perovskite layer and the electron transport layer. Summary of the Invention Problems to be Solved by the Invention

[0009] The present invention has been devised to solve the above-described problems. The problem to be solved by the present invention is to provide a surface treatment method for a perovskite solar cell that can remove defects generated on the surface of the perovskite, improve the alignment of the surface roughness and the energy level with the electron transport layer, and minimize the efficiency degradation of the perovskite solar cell. Means for Solving the Problems

[0010] (1) To solve the above-described technical problems, the present invention includes the step of forming a light absorption layer containing a perovskite compound represented by the following Chemical Formula 1-1; and (2) treating the light absorption layer with a perovskite surface treatment solution containing two or more compounds capable of substituting at the A 1 or A 2 site of the compound of Chemical Formula 1-1 to form an interface layer; and (3) forming an electron transport layer on the interface layer; to provide a method for manufacturing a perovskite solar cell. [Chemical Formula 1-1] A 1 a A 2 1-a Pb(X 1 b X 2 1-b )3

[0011] In Chemical Formula 1-1, A 1 is a monovalent metal cation, A 2 is a monovalent organic cation, X 1 and X 2 are different halogen ions from each other, a is a real number between 0 and 0.25. b is a real number between 0 and 1.

[0012] In a preferred embodiment of the present invention, in step (1), the A in chemical formula 1-1 2 C1~C 10 It may be an ammonium ion or amidinium ion substituted or unsubstituted with one or more aliphatic or aromatic hydrocarbons.

[0013] In a preferred embodiment of the present invention, in step (1), the A in chemical formula 1-1 2 This can be one selected from among formamidinium, phenethylammonium, ethylammonium, methylammonium, and dimethylammonium ions.

[0014] In a preferred embodiment of the present invention, in step (2), compound A of chemical formula 1-1 is 1 Or A 2 The compounds that can be substituted at the site are those represented by the chemical formula 2 below, C3-C 10 Carboxylic acids, C3-C 10 Phosphoric acid (phosphorous acid) having carbon atoms and C3~C 10 It may be any one of the thiol compounds having carbon atoms. [Chemical formula 2] A' X'

[0015] In the above chemical formula 2, A′ is a monovalent metal cation or C1-C 10 Ammonium ions or amidinium ions substituted or unsubstituted with one or more aliphatic or aromatic hydrocarbons It is a muion, X′ is a halogen anion or a -SCN anion.

[0016] In one preferred embodiment of the present invention, in step (2), two or more compounds of chemical formula 1-1 contained in the perovskite surface treatment solution are A 1 Or A 2 At least one of the compounds that can be substituted at the site is the A of the perovskite compound contained in the light absorption layer. 1 Ions or A 2 It may also contain at least one of the same ions.

[0017] In one preferred embodiment of the present invention, in step (2), the A1 ion or A of the compound of chemical formula 1-1 is used in step (2). 2 A of a compound with chemical formula 1-1 that contains at least one of the same ions. 1 Or A 2 The compounds that can be substituted at the site are two or more compounds of chemical formula 1-1 contained in the perovskite surface treatment solution. 1 Or A 2 It may also be present in an amount of 50 wt% to 75 wt% relative to the total weight of the compounds that can be substituted at the site.

[0018] In a preferred embodiment of the present invention, in step (2), the perovskite surface treatment solution is prepared using a C2-C8 alcohol as a solvent, and the A compound of chemical formula 1-1 is used. 1 Or A 2 The material may contain two or more substitutable compounds at a concentration of 2 mM to 15 mM.

[0019] The present invention also transparent electrode layer; Hole transport layer (HTL) formed on the transparent electrode layer; A perovskite light-absorbing layer formed on the hole transport layer, comprising a perovskite compound represented by the following chemical formula 1-1; Formed on the perovskite light-absorbing layer, and the perovskite compound A 1 Or A 2A compound that can be substituted at the site, represented by the chemical formula 2 below, C3-C 10 Carboxylic acids, C3-C 10 Phosphoric acid (phosphorous acid) having carbon atoms and C3~C 10 An interfacial layer containing two or more compounds selected from thiol compounds having carbon atoms; An electron transport layer (ETL) formed on the interface layer; and The present invention provides a perovskite solar cell comprising an upper electrode layer formed on the electron transport layer. [Chemical formula 1-1] A 1 a A 2 1-a Pb(X 1 b X 2 1-b )3 [Chemical formula 2] A' X'

[0020] In the aforementioned chemical formula 1, A 1 A is a monovalent metal cation. 2 It is a monovalent organic cation, X 1 and X 2 These are all different halogen ions, a is a real number between 0 and 0.25. b is a real number between 0 and 1. In the aforementioned chemical formula 2, A′ is a monovalent metal cation or C1~C 10 The ammonium ion or amidinium ion is substituted or unsubstituted with one or more aliphatic or aromatic hydrocarbons. X′ is a halogen anion or a -SCN anion.

[0021] In one preferred embodiment of the present invention, The energy level difference between the LUMO energy level of the interface layer and the LUMO energy level of the perovskite light-absorbing layer may be 0.3 eV or less. More preferably, 0.1 eV. It may be less than V.

[0022] In one preferred embodiment of the present invention, the electron transport layer may contain fullerene. [Effects of the Invention]

[0023] Unlike conventional techniques that use a single material to remove surface defects in the perovskite layer of a perovskite solar cell, when manufacturing a perovskite solar cell using the method according to the present invention, the energy levels of the electron transport layer and the perovskite layer can be easily matched, and the current (J) of the solar cell can be controlled. SC ), can improve the fill factor, and remove anion or cation defects from the surface of the perovskite layer by applying a voltage (V OC This has the advantage of improving the solar panel's efficiency, ultimately maximizing its effectiveness.

[0024] Furthermore, by applying a perovskite cell structure with the same structure as the perovskite solar cell of the present invention to the upper cell of a silicon solar cell, a silicon / perovskite 2-terminal tandem series solar cell is fabricated. This results in improved VOC compared to a silicon / perovskite 2-terminal tandem cell using a conventional perovskite solar cell, rather than the perovskite solar cell of the present invention, ultimately maximizing the efficiency of the tandem solar cell. [Brief explanation of the drawing]

[0025] [Figure 1] Figure 1 is a schematic diagram showing the layered structure of a perovskite solar cell that has undergone surface treatment according to a preferred embodiment of the present invention. [Figure 2]Figure 2 schematically shows the layered structure of a perovskite solar cell that has undergone surface treatment according to a preferred embodiment of the present invention. [Figure 3] Figure 3 illustrates how surface defects in a perovskite layer are affected by compounds contained in the surface treatment solution when surface treatment is performed using conventional techniques. The precursors in the surface treatment solution react with the perovskite surface defects, altering the perovskite surface properties. This alteration may have a positive or negative effect on the perovskite solar cell. [Figure 4] Figure 4a compares the energy levels (the middle line is the energy level graph, the upper part is the LUMO, and the lower part is the HOMO) that changed when a perovskite surface treatment was performed by the present invention (blue) and the prior art (red), with the energy levels of the perovskite layer (left) and the energy levels of the electron transport layer (right). Figure 4b compares the charge flow between the perovskite layer and the electron transport layer when the perovskite layer is surface treated by the prior art (left) and when the perovskite layer is surface treated by a preferred embodiment of the present invention (right). [Figure 5] Figure 5 is a diagram comparing the principles of charge transfer operation when the perovskite layer is surface-treated by the conventional technique and when it is surface-treated by a preferred embodiment of the present invention. [Modes for carrying out the invention]

[0026] Prior to a detailed description of the structure and effects of the present invention, the meanings of terms used herein will be explained.

[0027] In this specification, "perovskite compound" means an inorganic compound having the same crystal structure as calcium titanate (CaTiO3). In particular, A + B 2+ X - It consists of 3 ionic bonds.

[0028] In this specification, "A compound of chemical formula 1" 1Or A 2 A "substitutable compound" is defined as the compound in the following chemical formula 1 where A 1 and A 2 Since it is a monovalent cation, it means a compound that has a monovalent cation that can be substituted at the site of that compound. Also, carboxylic acids, phosphoric acid, thiols, etc., which release hydrogen cations, and Pb + This also includes organic compounds that can act as ligands capable of binding to the perovskite surface. This substance is used as a surface treatment material for the A site (i.e., A) of the perovskite surface. 1 Or A 2 (site) is replaced by or surface defects (Pb + (A substance that can bind with) [Chemical formula 1] A 1 a A 2 1-a BX3

[0029] In the above chemical formula 1, A 1 , A 2 A is a monovalent cation, and a1 and a2 are real numbers between 0 and 1 that add up to 1. When a is 0, chemical formula 1 is A 2 When it becomes BX3 and a is 1, chemical formula 1 is A 1 This results in BX3. B is a divalent metal cation, preferably a divalent transition metal cation. More preferably, B is a lead (Pb) cation.

[0030] The configuration and effects of the present invention will be described in more detail below.

[0031] As described above, the present invention relates to (1) the step of forming a light-absorbing layer comprising a perovskite compound represented by the following chemical formula 1-1; and (2) Compound A of the following chemical formula 1-1 is placed on the light-absorbing layer. 1 Or A 2 A step of treating the surface with a perovskite surface treatment solution containing two or more compounds that can be substituted at the site to form an interfacial layer; and (3) Forming an electron transport layer on the interface layer; A method for manufacturing a perovskite solar cell is provided, which includes this step. [Chemical formula 1-1] A 1 a A 2 1-a Pb(X 1 b X 2 1-b )3

[0032] In the chemical formula 1-1, A 1 is a cesium (Cs) cation, A 2 is a monovalent organic cation, and X 1 and X 2 are different halogen ions from each other, a is a real number from 0 to 0.25, b is a real number from 0 to 1.

[0033] The present invention is developed to prevent the problem that in a perovskite solar cell, due to the defect problem of the perovskite layer between the perovskite layer and the electron transport layer, the electron transport ability and further the performance of the perovskite solar cell are degraded. As a result of using a substance that can be substituted at a single A ion site in the surface treatment technology of the perovskite layer used in the conventional technology, a high energy barrier is generated and the efficiency of the solar cell is reduced. The present invention combines and uses substances that can be substituted at two or more A ion sites, and as a result, the energy alignment between the perovskite layer and the interface layer formed by surface treatment is improved, and the efficiency of the solar cell can be significantly increased.

[0034] In a preferred embodiment of the present invention, in the step (1), A in the chemical formula 1-1 2 can be an ammonium ion or an amidinium ion substituted or unsubstituted with one or more aliphatic or aromatic hydrocarbons of C1 to C 10 .

[0035] Also, in a preferred embodiment of the present invention, in the step (1), the A in Chemical Formula 1-1 2 is one selected from formamidinium, phenethylammonium , ethylammonium, methylammonium, and dimethylammonium ions.

[0036] More preferably, in the step (1), the perovskite compound represented by Chemical Formula 1-1 may be a compound represented by the following Chemical Formula 1-2. [Chemical Formula 1-2] Cs a FA 1-a Pb(I b Br 1-b )3

[0037] In Chemical Formula 1-2, Cs represents a cesium cation, and FA represents a formamidinium cation. Also, a is a real number from 0 to 0.25, and b is a real number from 0 to 1.

[0038] [[ID=2,8]]In a preferred embodiment of the present invention, in the step (2), the compound capable of substituting the A[[ID=,31]] 1 or A[[ID=3,3]] 2 site of the Chemical Formula 1-1 compound may be a compound represented by the following Chemical Formula 2, a carboxylic acid having C3 to C 10 carbons, a phosphorous acid having C3 to C 10 carbons, or a thiol compound having C3 to C 10 carbons, and may be any one of them. [Chemical Formula 2] A′X′

[0039] In Chemical Formula 2, A′ is a monovalent metal cation or C1 to C 10X′ is an ammonium ion or amidinium ion substituted or unsubstituted with one or more aliphatic or aromatic hydrocarbons, where X′ is a halogen anion or - This is an SCN anion.

[0040] In one preferred embodiment of the present invention, In step (2) above, two or more compounds of chemical formula 1-1 contained in the perovskite surface treatment solution are A 1 Or A 2 At least one of the compounds that can be substituted at the site is the A of the perovskite compound contained in the light absorption layer. 1 Ions or A 2 It may also contain at least one of the same ions.

[0041] The present invention relates to the A of perovskite compounds contained in the light-absorbing layer. 1 Or A 2 By treating the surface with a surface treatment solution containing a compound that contains the same cation as the cation, and with a mixed solution containing such a compound and other compounds that can substitute for other A cation sites, the energy barrier can be reduced and electron mobility can be further improved compared to treatment with a single compound.

[0042] In one preferred embodiment of the present invention, In step (2) above, compound A of chemical formula 1-1 1 Ions or A 2 Compound A of chemical formula 1-1, which contains at least one of the same ions. 1 Or A 2 The compounds that can be substituted at the site are two or more compounds of chemical formula 1-1 contained in the perovskite surface treatment solution. 1 Or A 2 It may also be present in an amount of 50 wt% to 75 wt% relative to the total weight of the compounds that can be substituted at the site.

[0043] More preferably, A of the chemical formula 1-1 compound 1 Or A 2Among the compounds that can be substituted at the cation site, perovskite compounds A included in the light absorption layer 1 Cation or A 2 Compounds containing the same cation as one of the cations may be present in an amount of 60 wt% to 70 wt% of the total weight.

[0044] The surface treatment solution in step (2) is preferably compound A of the chemical formula 1-1. 1 Ions or A 2 The solution may be a mixed solution containing two or three compounds that can be replaced at ion sites. More preferably, it may be a solution containing two compounds.

[0045] In one preferred embodiment of the present invention, The perovskite surface treatment solution in step (2) above uses a C2-C8 alcohol as a solvent, and the A of the chemical formula 1 compound 1 Or A 2 The material may contain two or more substitutable compounds at a concentration of 2 mM to 15 mM.

[0046] The solvent may preferably be isopropyl alcohol (IPA).

[0047] Furthermore, the concentration of the surface treatment solution may more preferably be 7 mM to 10 mM.

[0048] The present invention also A transparent electrode layer; a hole transport layer (HTL) formed on the transparent electrode layer; a perovskite light absorption layer formed on the hole transport layer and containing a perovskite compound represented by the following chemical formula 1-1; and a perovskite light absorption layer formed on the perovskite light absorption layer and containing the perovskite compound A 1 Or A 2 A compound that can be substituted at the site, represented by the chemical formula 2 below, C3-C 10 Carboxylic acids, C3-C 10 Phosphoric acid (phosphorous acid) having carbon atoms and C3~C 10The present invention provides a perovskite solar cell comprising: an interface layer containing two or more compounds selected from thiol compounds having carbon; an electron transport layer (ETL) formed on the interface layer; and an upper electrode layer formed on the electron transport layer. [Chemical formula 1-1] A 1 a A 2 1-a Pb(X 1 b X 2 1-b )3 [Chemical formula 2] A' X'

[0049] In the above chemical formula 1-1, A 1 A is a monovalent metal cation. 2 It is a monovalent organic cation, X 1 and X 2 These are all different halogen ions, a is a real number between 0 and 0.25. b is a real number between 0 and 1. In the aforementioned chemical formula 2, A′ is a monovalent metal cation or C1~C 10 The ammonium ion or amidinium ion is substituted or unsubstituted with one or more aliphatic or aromatic hydrocarbons. X′ is a halogen anion or a -SCN anion.

[0050] In one preferred embodiment of the present invention, The energy level difference between the LUMO energy level of the interface layer and the LUMO energy level of the perovskite light-absorbing layer may be 0.3 eV or less. More preferably, it may be 0.1 eV or less.

[0051] In a preferred embodiment of the present invention, the interface layer may be formed with a thickness of 0.5 nm to 2 nm. If the thickness is less than 0.5 nm, the effect of the surface treatment may not be sufficient. However, conversely, if the thickness exceeds 2 nm, the electron mobility may decrease due to barrier properties, which may actually lower the efficiency of the solar cell.

[0052] In one preferred embodiment of the present invention, the electron transport layer may contain fullerene. More preferably, C 60 It may contain fullerene (Buckminsterfullerene).

[0053] Other solar cell configurations can adopt configurations commonly used in the industry for the operation of perovskite solar cells, which are selected from configurations that are easily chosen by the average technician.

[0054] The configuration and effects of the present invention will be described in detail below based on specific examples. The following examples are illustrative of embodiments to aid in understanding the present invention and are not intended to limit the scope of the present invention.

[0055] <Examples>

[0056] Example 1 As the first electrode, a 2.5 cm x 2.5 cm ITO conductive transparent substrate was placed in a sodium hydroxide cleaning solution, ultrasonically cleaned for 1 hour, then washed with distilled water and ethanol, and dried under a nitrogen gas atmosphere. After partially etching the cleaned ITO conductive transparent substrate with an IR laser, a 30 nm thick NiO₂ layer was used as a hole transport layer using a vapor deposition process. x (NiO x is Ni 2+ / Ni 3+ It formed a layer of material in which these two substances coexist.

[0057] After that, NiO xA 200 μl solution with a concentration of 1 mM to 5 mM was dropped onto the layer as an organic interface layer solution, and the layer was spin-coated at 3000 rpm for 30 seconds, followed by heat treatment at 100°C. Cs was then added on top of that. 0.2 FA 0.8 Pb(I 0.8 Br 0.2 A solution containing a perovskite precursor having the chemical formula )3 was dropped with 100 μl (FA is formamidinium), and while spin-coating at 5000 rpm for 30 seconds, 99% pure nitrogen was blown onto it, and the mixture was heat-treated at 100°C for 20 minutes to form a perovskite light-absorbing layer with a final thickness of 500 nm.

[0058] Subsequently, a 14 mM solution of PEAI / FAI mixed in a weight ratio of 36:64 was applied to the formed light absorption layer as a surface treatment solution, and a 13 nm thick C layer was then applied on top of it as an electron transport layer. 60 A layer was formed. 200 μl of a solution of 1 mg of bathocuproine (BCP) dissolved in 1 ml of isopropyl alcohol (IPA) was dropped onto the formed electron transport layer. This was then spin-coated at 4000 rpm for 30 seconds to form an exciton barrier layer. Finally, a second Ag electrode with a thickness of 100 nm was formed using a thermal deposition apparatus to fabricate a perovskite photoelectric conversion element.

[0059] Example 2 The procedure was carried out in the same manner as in Example 1, but the concentration of the surface treatment solution was changed to 10 mM to fabricate perovskite solar cells.

[0060] Example 3 The procedure was carried out in the same manner as in Example 1, but the concentration of the surface treatment solution was changed to 8 mM to fabricate perovskite solar cells.

[0061] Example 4 The procedure was carried out in the same manner as in Example 1, but the concentration of the surface treatment solution was changed to 6 mM to fabricate perovskite solar cells.

[0062] Example 5 The procedure was carried out in the same manner as in Example 1, but perovskite solar cells were fabricated by treating them with a surface treatment solution whose concentration was changed to 2 mM.

[0063] Example 6 The procedure was carried out in the same manner as in Example 1, but the concentration of the surface treatment solution was changed to 20 mM to fabricate perovskite solar cells.

[0064] Comparative Example 1 The procedure was carried out in the same manner as in Example 1, except that a layer of LiF was thermally deposited as an interface layer to fabricate a perovskite solar cell.

[0065] Comparative Example 2 The procedure was carried out in the same manner as in Example 1, but the perovskite light-absorbing layer was treated using an IPA solution containing 8 mM PEAI alone as the perovskite surface treatment solution, and a perovskite solar cell was fabricated.

[0066] Comparative Example 3 The procedure was carried out in the same manner as in Example 1, but the perovskite light-absorbing layer was treated using an IPA solution containing 8 mM FAI alone as the perovskite surface treatment solution, and a perovskite solar cell was fabricated.

[0067] [Table 1]

[0068] Experimental example: Measurement of open-circuit voltage, short-circuit current, filling efficiency, and efficiency.

[0069] The photoelectric conversion efficiency of the perovskite solar cells manufactured according to the above examples and comparative examples was measured using a solar simulator (Newport Co.). The measurement conditions were AM15G (1 sun, 100 mW / cm²). 2 The temperature is 25°C. The open-circuit voltage (V) measured through the experiment was OC ), short-circuit current (J SC ), filling rate (Fill The Factor and the resulting photoelectric conversion efficiency are shown in Table 2 below.

[0070] [Table 2]

[0071] Referring to Table 2 above, it can be seen that in Comparative Example 1, which has a LiF vapor-deposited interface layer, and in Comparative Examples 2 and 3, which use a single interface layer material, the photoelectric conversion efficiency is worse compared to the examples. In particular, in Comparative Examples 2 and 3, the photoelectric conversion efficiency was significantly lower compared to the examples.

[0072] When comparing Examples 1 to 4, it was found that Example 3, with a combined PEAI / FAI surface treatment solution of 8 mM, exhibited the best photoelectric conversion efficiency.

[0073] However, when comparing Examples 5 and 6 together, it was found that Example 5, with its low surface treatment solution concentration of 2 mM, and Example 6, with its excessively high concentration, exhibited lower photoelectric conversion efficiency compared to Example 3. In the explanation of the symbols, 100 represents a perovskite solar cell, 110 a metal electrode, 120 a transparent conductive oxide, 130 an electron transport layer, 140 a photoactive layer, 141 an interface layer, 150 a hole transport layer, 160 a BCP layer, and 200 a silicon solar cell.

Claims

1. (1) The step of forming a light-absorbing layer containing a perovskite compound represented by the following chemical formula 1-1; and (2) A of the following chemical formula 1-1 compound on the light-absorbing layer １ Or A ２ A step of treating the surface with a perovskite surface treatment solution containing two or more compounds that can be substituted at the site to form an interfacial layer; and (3) A method for manufacturing a perovskite solar cell, comprising the step of forming an electron transfer layer on the interface layer: [Chemical formula 1-1] A １ ａ A ２ １－ａ Pb(X １ ｂ X ２ １－ｂ ) ３ In the above chemical formula 1-1, A １ Cs cation, A ２ It is a monovalent organic cation, X １ and X ２ These are all different halogen ions, a is a real number between 0 and 0.

25. b is a real number between 0 and 1.

2. In step (1) above, A in chemical formula 1-1 ２ C １ ~C １０ A method for producing a perovskite solar cell according to claim 1, characterized in that the ammonium ions or amidinium ions are substituted or unsubstituted with one or more aliphatic or aromatic hydrocarbons.

3. In step (1) above, A in chemical formula 1-1 ２ The method for producing a perovskite solar cell according to claim 2, characterized in that is one selected from formamidinium, phenethylammonium, ethylammonium, methylammonium, and dimethylammonium ions.

4. In step (2) above, A of the chemical formula 1-1 １ Or A ２ The compounds that can be substituted at the site are the compounds shown in chemical formula 2 below, C ３ ~C １０ Carboxylic acid having a carbon atom, C ３ ~C １０ Phosphorous acid and C ３ ~C １０ A method for producing a perovskite solar cell according to claim 1, characterized in that it is one of the thiol compounds having carbon: [Chemical formula 2] A'X' In the above chemical formula 2, A' is a monovalent metal cation or C １ ~C １０ One or more aliphatic or aromatic hydrocarbons are substituted or unsubstituted ammonium ions or amidinium ions, X' is a halogen anion or － This is an SCN anion.

5. In step (2) above, two or more compounds of chemical formula 1-1 contained in the perovskite surface treatment solution are A １ Or A ２ At least one of the compounds that can be substituted at the site is, A perovskite compound A contained in the light-absorbing layer １ Ion or A ２ A method for producing a perovskite solar cell according to claim 4, characterized in that it contains at least one of the same ions.

6. In step (2) above, A of the chemical formula 1-1 １ Ion or A ２ Compound A of chemical formula 1-1 contains at least one of the same ions. １ Or A ２ Replaceable on site The compound that can perform the treatment is two or more compounds of chemical formula 1-1 contained in the perovskite surface treatment solution. １ Or A ２ A method for producing a perovskite solar cell according to claim 5, characterized in that it is included in an amount of 50 wt% to 75 wt% relative to the total weight of the compounds that can be substituted at the sites.

7. In step (2) above, the perovskite surface treatment solution is C ２ ~C ８ Using the alcohol as a solvent, Compound A of the aforementioned chemical formula 1-1 １ Or A ２ A method for producing a perovskite solar cell according to claim 1, characterized in that it contains two or more compounds that can be substituted at the sites, in a concentration of 2 mM to 15 mM.

8. transparent electrode layer; A hole transport layer (HTL) formed on the transparent electrode layer; A perovskite light-absorbing layer formed on the hole transport layer, comprising a perovskite compound represented by the following chemical formula 1-1; Formed on the perovskite light-absorbing layer, the perovskite compound A １ Or A ２ A compound that can be substituted at the site, and is represented by the following chemical formula 2 or C ３ ~C １０ Carboxylic acid having a carbon atom, C ３ ~C １０ Phosphorous acid and C ３ ~C １０ An interfacial layer comprising two or more compounds selected from thiol compounds having carbon atoms; An electron transport layer (ETL) formed on the interface layer; and A perovskite solar cell comprising an upper electrode layer formed on the electron transport layer: [Chemical formula 1-1] A １ ａ A ２ １－ａ Pb(X １ ｂ X ２ １－ｂ ) ３ [Chemical formula 2] A'X' In the above chemical formula 1-1, A １ A is a monovalent metal cation. ２ It is a monovalent organic cation, X １ and X ２ These are all different halogen ions, a is a real number between 0 and 0.

25. b is a real number between 0 and 1. In the aforementioned chemical formula 2, A' is a monovalent metal cation or C １ ~C １０ One or more aliphatic or aromatic hydrocarbons are substituted or unsubstituted ammonium ions or amidinium ions, X' is a halogen anion or － This is an SCN anion.

9. The perovskite solar cell according to claim 8, characterized in that the energy level difference between the LUMO energy level of the interface layer and the LUMO energy level of the perovskite light-absorbing layer is 0.3 eV or less.

10. The perovskite solar cell according to claim 9, characterized in that the energy level difference between the LUMO energy level of the interface layer and the LUMO energy level of the perovskite light absorption layer is 0.1 eV or less.

11. The perovskite solar cell according to claim 8, characterized in that the electron transport layer contains fullerene.

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