Perovskite homojunction solar cell and in-situ preparation method thereof

Abstract

The invention discloses a perovskite homojunction solar cell and an in-situ preparation method thereof. The perovskite homojunction solar cell comprises a transparent conductive substrate, an electron transport layer, a perovskite light absorption layer, a hole transport layer and an electrode which are sequentially arranged from bottom to top, according to the perovskite light absorption layer, doping agents are introduced in situ in the preparation process of the perovskite light absorption layer through an improved multi-step spin-coating method, control over spatial distribution of the doping agents in the perovskite light absorption layer is achieved, and the perovskite homojunction light absorption layer with adjustable properties is prepared; the perovskite light absorption layer adopts a homojunction structure, and a homojunction built-in electric field is utilized to enhance separation and transmission driving force of electrons and holes in the perovskite light absorption layer and inhibit recombination of the electrons and the holes. According to the invention, in-situ controllable preparation of the perovskite homojunction by the solution method is realized.

Description

Technical Field

[0001] The present invention belongs to the technical field of solar cells, and in particular relates to a perovskite homojunction solar cell and an in-situ preparation method thereof. Background Art

[0002] Currently, high-efficiency perovskite solar cells are all based on a planar structure. In this structure, the perovskite layer acts as a light-absorbing layer and is sandwiched between electron and hole transport layers on either side. Under the influence of incident light, photogenerated electrons and holes are generated within the perovskite layer. Under the influence of the electric fields at the perovskite / electron transport layer and perovskite / hole transport layer interfaces, the electrons and holes are separated and extracted to the cathode and anode, and then discharged to the external circuit, completing the photoelectric conversion process. In order to absorb as much incident light as possible within its photoresponse range, perovskite films generally need to have a certain thickness. However, even thicker perovskite films still contain a large number of photogenerated electrons and holes. These electrons and holes are only affected by the interfacial electric field and can only move to the interfacial electric field through diffusion to be separated and extracted. The photogenerated electrons and holes cannot be separated quickly, which greatly increases the probability of electron and hole recombination, thereby reducing device performance.

[0003] Theoretical studies have shown that the introduction of a built-in electric field through a homojunction can effectively increase the separation and transport of carriers within the perovskite film, inhibit the recombination of carriers within the film, and thus improve device efficiency. Perovskite materials have excellent solution processing properties, which can effectively reduce the cost of large-scale industrial production. However, their special properties also limit their difficulty in preparing homojunctions through diffusion, ion implantation, and other methods like traditional semiconductors such as silicon and gallium arsenide. There are currently two main approaches to the preparation of perovskite homojunctions: one is to utilize the self-doping effect of perovskites, control the ratio of precursor components through vacuum evaporation, and prepare N-type and P-type perovskite films in sequence, so as to achieve perovskite homojunctions by stacking perovskite films of different conductivity types. Although this method can obtain high-quality perovskite homojunctions, the vacuum method greatly increases the preparation cost of perovskite films, which is not conducive to their large-scale commercial application.

[0004] Another method for preparing perovskite homojunctions is to perform surface treatment on perovskite films prepared by the solution method. Surface doping or charge transfer mechanisms can also be used to achieve a change in the surface conductivity type of the perovskite film, thereby constructing a perovskite homojunction. However, this method still has some problems. First, surface treatment increases the preparation process of perovskite solar cells and increases manufacturing costs. Second, surface treatment is a mild post-treatment method performed on the prepared perovskite film, which results in it only being able to achieve a conductivity type reversal in the shallow region below the surface of the perovskite film. The constructed homojunction is shallow and uncontrollable, and has limited effect on the carrier transport effect in the deeper layers of the perovskite film. The insufficient carrier driving force in the deep layers leads to increased carrier recombination, which affects the efficiency of the perovskite solar cell. Summary of the Invention

[0005] In order to overcome the deficiencies of the above-mentioned prior art, the present invention aims to provide a perovskite homojunction solar cell and an in-situ preparation method thereof, which provides an improved solution method for in-situ preparation of the perovskite homojunction, thereby improving the separation and transport driving force of carriers within the perovskite film, while improving the energy level matching of the perovskite / charge transport layer, suppressing the recombination of carriers within the device, and ultimately improving the efficiency of the perovskite solar cell. The perovskite homojunction adopts an improved multi-step solution method, introducing doping layers of different thicknesses by multi-step spin coating, and then combining the doping molecular radius selection and gradient annealing to control the spatial distribution of impurities within the perovskite film, thereby achieving a solution method for in-situ controllable preparation of the perovskite homojunction.

[0006] In order to achieve the above object, the technical solution adopted by the present invention is:

[0007] A perovskite homojunction solar cell comprises a transparent conductive substrate, an electron transport layer, a perovskite light absorption layer, a hole transport layer and an electrode arranged in sequence from bottom to top;

[0008] The perovskite light-absorbing layer adopts a homojunction structure, and utilizes the built-in electric field of the homojunction to enhance the separation and transmission driving force of electrons and holes in the perovskite light-absorbing layer, thereby suppressing the recombination of electrons and holes;

[0009] The homojunction structure is achieved by in-situ introduction of dopants by multi-step spin coating during the preparation of the perovskite light absorbing layer, thereby controlling the spatial distribution of the dopants within the perovskite light absorbing layer and making its properties adjustable.

[0010] The dopant is an alkali metal ion, a pseudo-halide anion BF4 - PF6 - , any organic molecule containing a strongly electronegative electron-withdrawing group.

[0011] The dopant accounts for 1-10% of the molar ratio of the perovskite light-absorbing layer. The perovskite light-absorbing layer converts incident light into electron-hole pairs, with the electrons and holes diffusing to the interfaces of the perovskite light-absorbing layer / electron transport layer and the perovskite light-absorbing layer / hole transport layer, respectively, and then being extracted to the electrode through the electron transport layer and the hole transport layer.

[0012] Furthermore, the transparent conductive substrate is made of indium tin oxide (ITO) or fluorine-doped tin oxide (FTO), and its thickness is 200-300 nm;

[0013] Furthermore, the electron transport layer is made of any one of n-type metal oxides titanium dioxide (TiO2), zinc oxide (ZnO), and tin dioxide (SnO2), and has a thickness of 10-50 nm;

[0014] Furthermore, the hole transport layer is made of Spiro-OMeTAD or PTAA, and has a thickness of 100-200 nm;

[0015] Furthermore, the electrode is a metal electrode made of any one of gold (Au), silver (Ag), copper (Cu) or aluminum (Al), wherein the thickness of the metal electrode is 80-120 nm.

[0016] A perovskite homojunction solar cell and an in-situ preparation method thereof, comprising the following steps:

[0017] Step 1, preparing an electron transport layer on a transparent conductive substrate;

[0018] Step 2: In-situ introduction of dopants into the electron transport layer by multi-step spin coating to prepare a perovskite light absorbing layer, wherein the dopants are alkali metal ions, pseudo halide anions BF4 - PF6 - Any of the organic molecules containing strong electronegative electron-withdrawing groups;

[0019] Step 3, preparing a hole transport layer on the perovskite light absorbing layer;

[0020] Step 4: preparing an electrode on the hole transport layer.

[0021] The step 1 is specifically as follows:

[0022] The transparent conductive substrate is ultrasonically cleaned at 40-60° C. for 10-30 minutes using glass cleaner, deionized water, acetone, and alcohol in sequence, and then dried with nitrogen. The transparent conductive substrate is then subjected to ultraviolet ozone treatment for 10-30 minutes.

[0023] Prepare a SnO2 electron transport layer on the transparent conductive substrate in step 1, dilute the 15wt% tin oxide hydrocolloid dispersion to 3-5wt% with deionized water, filter and spin-coat the diluted solution on the transparent conductive substrate.

[0024] In the step 1, the electron transport layer is prepared by filter spin coating on the transparent conductive substrate, and the implementation method is as follows;

[0025] Prepare a dispersion of electron transport layer material, set the spin coating speed to 2000-5000 rpm, the spin coating time to 20-60 s, and anneal the obtained film after spin coating at an annealing temperature of 100-200° C. for 20-60 min.

[0026] The perovskite light absorbing layer is prepared by in-situ introduction of dopants on the electron transport layer by multi-step spin coating. The implementation method is as follows:

[0027] Lead iodide (PbI2) is dissolved in a mixed solution of N,N-dimethylformamide (DMF) and dimethyl sulfoxide (DMSO), wherein the volume ratio of DMF to DMSO is 10:0-8:2, and stirred continuously until dissolved to obtain a PbI2 solution with a concentration of 0.8-1.6M;

[0028] Formamidine iodide (FAI) is dissolved in isopropyl alcohol (IPA) at a concentration of 10-100 mg / mL, and then methylamine chloride (MACl) is added at a concentration of 5%-50% of the FAI content to control the crystallization process of the perovskite light-absorbing layer. Stirring is continued until dissolved to obtain a FAI (MACl) / IPA solution;

[0029] Dopants are introduced into the FAI (MACl) / IPA solution to perform p-type doping on the perovskite light-absorbing layer (dopants include alkali metal ions or pseudo-halide anions BF4 - PF6 - etc., or any one of organic molecules containing a strongly electronegative electron-withdrawing group), with a doping concentration of 0.1-10 mg / mL to obtain a doped FAI (MACl) / IPA solution.

[0030] PbI2 solution, FAI(MACl) / IPA solution, and doped FAI(MACl) / IPA solution were spin-coated on the electron transport layer in sequence.

[0031] The specific steps of spin coating are:

[0032] The PbI2 solution is spin-coated at a speed of 1000-4500 rpm and a spin-coating time of 20-60 s. The obtained PbI2 film is then annealed at an annealing temperature of 60-100° C. and an annealing time of 1-10 min. A FAI (MACl) / IPA solution is spin-coated on the annealed PbI2 film at a spin-coating speed of 1500-4500 rpm and a spin-coating time of 20-60 s. The spin-coating process of the FAI (MACl) / IPA solution is repeated 1-5 times, wherein FAI and PbI2 diffuse with each other and react to obtain an undoped perovskite layer, the PbI2 content in the undoped perovskite layer is greater than that of FAI, and the undoped perovskite layer exhibits n-type; subsequently, a doped FAI (MACl) / IPA solution is spin-coated at a spin-coating speed of 1500-4500 rpm and a spin-coating time of 20-60 s. The spin-coating process of the doped FAI (MACl) / IPA solution is repeated 1-5 times to obtain a doped perovskite layer, and the doped perovskite layer exhibits p-type under the action of a dopant.

[0033] Then the film of the spin-coated doped FAI(MACl) / IPA solution was subjected to gradient annealing;

[0034] The specific steps of gradient annealing are:

[0035] The first step annealing temperature is 40-100° C., the annealing time is 1-30 minutes, and the second step annealing temperature is 100-200° C., the annealing time is 10-30 minutes; after the annealing is completed, a perovskite homojunction film is obtained.

[0036] The step 3 is specifically as follows:

[0037] Dissolve Spiro-OMeTAD in chlorobenzene to a concentration of 70-90 mg / mL, then add 15-20 μL of 400-600 mg / mL Li-TFSI / acetonitrile solution, 15-30 μL of 200-500 mg / mL FK209 / acetonitrile solution, and 15-30 μL of tBP solution to obtain a Spiro-OMeTAD solution.

[0038] The Spiro-OMeTAD solution was spin-coated on the perovskite film at a rotation speed of 1000-5000 rpm and a spin-coating time of 10-45 s to obtain a Spiro-OMeTAD hole transport layer.

[0039] In step 4, the evaporation chamber pressure is 5×10 -4 Pa below, evaporation rate The electrode thickness is 80-120nm.

[0040] Beneficial effects of the present invention:

[0041] The present invention can achieve similar preparation of homojunctions by combining two conductive types of perovskite films, while avoiding the shortcomings of the evaporation method, which is complex and not conducive to large-area preparation, and reduces the preparation cost of perovskite homojunction solar cells.

[0042] The present invention utilizes a full solution method to in-situ prepare a perovskite homojunction, effectively reducing the number of process steps required for the preparation of the perovskite homojunction, improving preparation efficiency, and reducing preparation costs. Furthermore, by regulating the spin coating speed and number of spin coatings of the undoped and doped FAI (MACl) / IPA solutions, changing the molecular size and doping concentration of the additives, and employing gradient annealing to control the thickness and doping concentration of the undoped and doped perovskite layers, perovskite homojunctions with varying junction depths and barrier heights can be prepared. This avoids the shortcomings of surface post-treatment methods, such as shallow and uncontrollable homojunction depths and poor carrier driving capabilities within the perovskite film, and enables wide-scale regulation of the perovskite homojunction properties. The built-in electric field of the perovskite homojunction is used to enhance the separation and transmission driving force of photogenerated electrons and holes inside the perovskite film, inhibiting the recombination of electrons and holes inside the perovskite film. At the same time, the upper and lower surfaces of the perovskite homojunction film exhibit p-type and n-type respectively, which can improve the energy level matching between the perovskite homojunction and the interface of the electron transport layer and the hole transport layer, improve the extraction efficiency of interface electrons and holes, and ultimately improve the efficiency of the device.

[0043] The method of the present invention can realize the in-situ preparation and property regulation of perovskite homojunction at a relatively low cost. BRIEF DESCRIPTION OF THE DRAWINGS

[0044] Figure 1 It is a schematic diagram of the process structure of the present invention. DETAILED DESCRIPTION

[0045] The present invention will be described in further detail below with reference to the accompanying drawings.

[0046] like Figure 1 As shown, the present invention provides a method for in-situ preparation of perovskite homojunction solar cells based on a full solution method, and is not limited to what is described in the specification and implementation methods.

[0047] The present invention enhances the separation and transmission of carriers inside the perovskite film and improves the performance of the perovskite solar cell.

[0048] A perovskite homojunction solar cell, comprising:

[0049] Transparent conductive substrate;

[0050] an electron transport layer, located on the transparent conductive substrate;

[0051] a perovskite light-absorbing layer, located on the electron transport layer;

[0052] a hole transport layer, located on the perovskite light absorbing layer;

[0053] The electrode is located on the hole transport layer.

[0054] The perovskite light-absorbing layer converts incident light into electron-hole pairs. The electrons and holes diffuse to the interfaces of the perovskite light-absorbing layer / electron transport layer and the perovskite light-absorbing layer / hole transport layer, respectively, and are extracted to the electrodes through the electron transport layer and the hole transport layer. The perovskite light-absorbing layer adopts a homojunction structure, and the built-in electric field of the homojunction enhances the driving force for the separation and transmission of electrons and holes within the perovskite light-absorbing layer, inhibiting the recombination of electrons and holes and improving the performance of the perovskite solar cell.

[0055] Furthermore, the perovskite homojunction light-absorbing layer is prepared by an improved multi-step spin coating method, and its thickness is 300-600 nm. By in-situ introduction of dopants during the preparation of the perovskite light-absorbing layer by the improved multi-step spin coating method, the spatial distribution of the dopants in the perovskite light-absorbing layer can be controlled, and ultimately a perovskite homojunction light-absorbing layer with adjustable properties is prepared.

[0056] Furthermore, the transparent conductive substrate is made of indium tin oxide (ITO) or fluorine-doped tin oxide (FTO), and its thickness is 200-300 nm;

[0057] Furthermore, the electron transport layer is made of any one of n-type metal oxides titanium dioxide (TiO2), zinc oxide (ZnO), and tin dioxide (SnO2), and has a thickness of 10-50 nm;

[0058] Furthermore, the hole transport layer is made of Spiro-OMeTAD or PTAA, and has a thickness of 100-200 nm;

[0059] Furthermore, the electrode is a metal electrode made of any one of gold (Au), silver (Ag), copper (Cu) or aluminum (Al), wherein the thickness of the metal electrode is 80-120 nm.

[0060] A perovskite homojunction solar cell and an in-situ preparation method thereof, comprising the following steps:

[0061] Step 1: ultrasonically clean the transparent conductive substrate using glass cleaner, deionized water, acetone, and alcohol at 40-60° C. for 10-30 minutes, then blow dry the cleaned transparent conductive substrate with nitrogen, and perform ultraviolet ozone treatment on the transparent conductive substrate for 10-30 minutes to remove residual organic matter on the substrate surface and improve the wettability of the transparent conductive substrate; obtaining the treated transparent conductive substrate;

[0062] Step 2: Prepare a tin oxide (SnO2) electron transport layer on the transparent conductive substrate described in step 1, dilute a 15 wt% tin oxide hydrocolloid dispersion to 3-5 wt% with deionized water, filter the diluted solution, and spin-coat it on the transparent conductive substrate;

[0063] The specific method steps of filter spin coating are:

[0064] The spin coating speed is 2000-5000 rpm, the spin coating time is 20-60 s, and the film is annealed after the spin coating is completed, the annealing temperature is 100-200° C., and the annealing time is 20-60 min to obtain an electron transport layer.

[0065] Step 3: Prepare the FAPbI3 perovskite homojunction light absorbing layer on the electron transport layer obtained in step 2 by multi-step spin coating. The preparation process is as follows: Figure 1 shown.

[0066] The specific steps of preparing the FAPbI3 perovskite homojunction light-absorbing layer by multi-step spin coating are:

[0067] Lead iodide (PbI2) is dissolved in a mixed solution of N,N-dimethylformamide (DMF) and dimethyl sulfoxide (DMSO) (the volume ratio of DMF and DMSO is 10:0-8:2), and stirred continuously until dissolved to obtain a PbI2 solution with a concentration of 0.8-1.6M; formamidine iodide (FAI) is dissolved in isopropyl alcohol (IPA) with a concentration of 10-100 mg / mL, and then methylamine chloride (MACl) accounting for 5%-50% of the FAI content is added to regulate the crystallization process of the perovskite light absorbing layer, and stirred continuously until dissolved to obtain a FAI (MACl) / IPA solution; a dopant is introduced into the FAI (MACl) / IPA solution to perform p-type doping on the perovskite light absorbing layer, (the dopant includes an alkali metal ion or a pseudo-halide anion BF4 - PF6 - The doping concentration is 0.1-10 mg / mL to obtain a doped FAI(MACl) / IPA solution. The PbI2 solution, FAI(MACl) / IPA solution, and doped FAI(MACl) / IPA solution are sequentially spin-coated on the electron transport layer.

[0068] The specific steps of spin coating are:

[0069] The PbI2 solution is spin-coated at a speed of 1000-4500 rpm and a spin-coating time of 20-60 s. The obtained PbI2 film is then annealed at an annealing temperature of 60-100° C. and an annealing time of 1-10 min.

[0070] Spin coat the FAI(MACl) / IPA solution on the annealed PbI2 film at a speed of 1500-4500 rpm for 20-60 s. Repeat the FAI(MACl) / IPA solution spin coating process 1-5 times ( Figure 1 A times), wherein FAI and PbI2 diffuse with each other and react to obtain an undoped perovskite layer, the PbI2 content in the undoped perovskite layer is greater than that of FAI, and the undoped perovskite layer exhibits n-type; subsequently, the doped FAI (MACl) / IPA solution is spin-coated at a spin-coating speed of 1500-4500 rpm and a spin-coating time of 20-60 s, and the doped FAI (MACl) / IPA solution spin-coating process is repeated 1-5 times ( Figure 1 B times), a doped perovskite layer is obtained, and the doped perovskite layer exhibits p-type under the action of the dopant.

[0071] Then the film of the spin-coated doped FAI(MACl) / IPA solution was subjected to gradient annealing;

[0072] The specific steps of gradient annealing are:

[0073] The first step of annealing is performed at a temperature of 40-100°C for 1-30 minutes, and the second step of annealing is performed at a temperature of 100-200°C for 10-30 minutes. After the annealing is completed, a perovskite homojunction film is obtained.

[0074] Step 4: preparing a hole transport layer Spiro-OMeTAD on the perovskite homojunction film described in step 3;

[0075] Step 4 is as follows:

[0076] Dissolve Spiro-OMeTAD in chlorobenzene to a concentration of 70-90 mg / mL, then add 15-20 μL of 400-600 mg / mL Li-TFSI / acetonitrile solution, 15-30 μL of 200-500 mg / mL FK209 / acetonitrile solution, and 15-30 μL of tBP solution to obtain a Spiro-OMeTAD solution.

[0077] The Spiro-OMeTAD solution was spin-coated on the perovskite film at a rotation speed of 1000-5000 rpm and a spin-coating time of 10-45 s to obtain a Spiro-OMeTAD hole transport layer.

[0078] Step 5: Prepare metal electrodes such as Au, Ag, Cu, and Al on the hole transport layer described in step 4 by thermal evaporation. The chamber pressure is 5×10 -4 Pa below, evaporation rate The electrode thickness is 80-120nm.

[0079] The improved solution method of the present invention can also be used to prepare perovskite homojunction films of other components, including MAPbI3, CsPbI3, CsPbI2Br, CsPbIBr2, CsPbBr3, etc.

[0080] In addition, this method can also be used to prepare perovskite homojunction solar cells based on a planar inverted structure. It includes:

[0081] Transparent conductive substrate;

[0082] a hole transport layer, located on the transparent conductive substrate;

[0083] a perovskite homojunction light-absorbing layer, located on the hole transport layer;

[0084] an electron transport layer, located on the perovskite homojunction light absorbing layer;

[0085] The electrode is located on the electron transport layer.

[0086] The perovskite light-absorbing layer adopts a homojunction structure to enhance the carrier separation and transmission driving force inside the perovskite light-absorbing layer, inhibit carrier recombination, and improve the performance of perovskite solar cells.

[0087] Furthermore, the perovskite homojunction light-absorbing layer is prepared by an improved multi-step spin coating method, and its thickness is 300-600 nm;

[0088] Furthermore, the transparent conductive substrate is made of indium tin oxide (ITO) or fluorine-doped tin oxide (FTO), and its thickness is 200-300 nm;

[0089] Furthermore, the hole transport layer is made of any one of p-type inorganic materials such as nickel oxide (NiO), CuO, Cu2O, etc., and p-type organic materials such as PEDOT, PTAA, and self-assembled layers (SAMs), and has a thickness of 5-50 nm;

[0090] Furthermore, the electron transport layer is made of n-type materials such as PCBM and C60, and has a thickness of 10-200 nm;

[0091] Furthermore, the electrode is a metal electrode made of any one of gold (Au), silver (Ag), copper (Cu) or aluminum (Al), wherein the thickness of the metal electrode is 80-120 nm.

[0092] The preparation method of the perovskite homojunction is similar to that of the perovskite homojunction in the perovskite solar cell based on the planar forward structure. The difference is that when preparing the perovskite homojunction in the planar reverse structure, the doped FAI (MACl) / IPA solution is first spin-coated on the annealed PbI2, and then the undoped FAI (MACl) / IPA solution is spin-coated. The dopant and spin-coating steps are the same as those in the planar forward structure, forming a structure with a doped perovskite layer at the bottom and an undoped perovskite layer at the top.

Claims

1. A perovskite homojunction solar cell, characterized in that: It includes a transparent conductive substrate, an electron transport layer, a perovskite light absorption layer, a hole transport layer and an electrode arranged in sequence from bottom to top; The perovskite light-absorbing layer adopts a homojunction structure, and utilizes the built-in electric field of the homojunction to enhance the separation and transmission driving force of electrons and holes in the perovskite light-absorbing layer, thereby suppressing the recombination of electrons and holes; The homojunction structure is achieved by in-situ introduction of dopants by multi-step spin coating during the preparation of the perovskite light absorbing layer, thereby controlling the spatial distribution of the dopants within the perovskite light absorbing layer and making its properties adjustable.

2. A perovskite homojunction solar cell according to claim 1, characterized in that: The perovskite light absorption layer converts incident light into electron-hole pairs, and the electrons and holes diffuse to the interfaces of the perovskite light absorption layer / electron transport layer and the perovskite light absorption layer / hole transport layer respectively, and are extracted to the electrode through the electron transport layer and the hole transport layer.

3. The perovskite homojunction solar cell according to claim 1, characterized in that: The transparent conductive substrate is made of ITO or FTO, and has a thickness of 200-300 nm; The electron transport layer is made of any one of TiO2, ZnO, and SnO2, and has a thickness of 10-50 nm; The hole transport layer is made of Spiro-OMeTAD or PTAA, and has a thickness of 100-200 nm; The electrode is any one of metal electrodes Au, Ag, Cu or Al, wherein the thickness of the metal electrode is 80-120 nm; The dopant is an alkali metal ion, a pseudo-halide anion BF4 - PF6 - , any one of organic molecules containing strongly electronegative electron-withdrawing groups; The molar ratio of the dopant to the perovskite light absorbing layer is 1-10%.

4. An in-situ preparation method for perovskite homojunction solar cells, characterized in that: The following steps are involved: Step 1, preparing an electron transport layer on a transparent conductive substrate; Step 2: In-situ introduction of dopants into the electron transport layer by multi-step spin coating to prepare a perovskite light absorbing layer, wherein the dopants are alkali metal ions, pseudo halide anions BF4 - PF6 - , any one of organic molecules containing strongly electronegative electron-withdrawing groups; Step 3, preparing a hole transport layer on the perovskite light absorbing layer; Step 4: preparing an electrode on the hole transport layer.

5. The in-situ preparation method of a perovskite homojunction solar cell according to claim 4, characterized in that: The step 1 is specifically as follows: The transparent conductive substrate is ultrasonically cleaned at 40-60° C. for 10-30 minutes using glass cleaner, deionized water, acetone, and alcohol in sequence, and then dried with nitrogen. The transparent conductive substrate is then subjected to ultraviolet ozone treatment for 10-30 minutes. Prepare a SnO2 electron transport layer on the transparent conductive substrate in step 1, dilute the 15wt% tin oxide hydrocolloid dispersion to 3-5wt% with deionized water, filter and spin-coat the diluted solution on the transparent conductive substrate.

6. The in-situ preparation method of a perovskite homojunction solar cell according to claim 4, characterized in that: In the step 1, the electron transport layer is prepared by filter spin coating on the transparent conductive substrate, and the implementation method is as follows; Prepare a dispersion of electron transport layer material, set the spin coating speed to 2000-5000 rpm, the spin coating time to 20-60 s, and anneal the obtained film after spin coating at an annealing temperature of 100-200° C. for 20-60 min.

7. The in-situ preparation method of a perovskite homojunction solar cell according to claim 4, characterized in that: The perovskite light absorbing layer is prepared by in-situ introduction of dopants on the electron transport layer by multi-step spin coating. The implementation method is as follows: Dissolve PbI2 in a mixed solution of DMF and DMSO, wherein the volume ratio of DMF to DMSO is 10:0-8:2, and continue stirring until dissolved to obtain a PbI2 solution with a concentration of 0.8-1.6M; Dissolve FAI in IPA at a concentration of 10-100 mg / mL, then add 5%-50% of the FAI content of MACl to regulate the crystallization process of the perovskite light-absorbing layer, and continue stirring until dissolved to obtain a FAI (MACl) / IPA solution; Introducing a dopant into the FAI(MACl) / IPA solution to perform p-type doping on the perovskite light-absorbing layer, with a doping concentration of 0.1-10 mg / mL, to obtain a doped FAI(MACl) / IPA solution; PbI2 solution, FAI(MACl) / IPA solution, and doped FAI(MACl) / IPA solution were spin-coated on the electron transport layer in sequence.

8. The in-situ preparation method of a perovskite homojunction solar cell according to claim 7, characterized in that: The specific steps of spin coating are: The PbI2 solution is spin-coated at a speed of 1000-4500 rpm for 20-60 s, and the resulting PbI2 film is then annealed at a temperature of 60-100°C for 1-10 min. Spin coating the annealed PbI2 film with a FAI (MACl) / IPA solution at a spin coating speed of 1500-4500 rpm for 20-60 s, and repeating the FAI (MACl) / IPA solution spin coating process 1-5 times, wherein FAI and PbI2 diffuse with each other and react to obtain an undoped perovskite layer, wherein the PbI2 content in the undoped perovskite layer is greater than that of FAI, and the undoped perovskite layer exhibits n-type; subsequently, spin coating the doped FAI (MACl) / IPA solution at a spin coating speed of 1500-4500 rpm for 20-60 s, and repeating the doped FAI (MACl) / IPA solution spin coating process 1-5 times to obtain a doped perovskite layer, wherein the doped perovskite layer exhibits p-type under the action of the dopant; Then the film of the spin-coated doped FAI(MACl) / IPA solution was subjected to gradient annealing; The specific steps of gradient annealing are: the first step annealing temperature is 40-100° C., the annealing time is 1-30 minutes, and the second step annealing temperature is 100-200° C., the annealing time is 10-30 minutes; after the annealing is completed, a perovskite homojunction film is obtained.

9. The in-situ preparation method of a perovskite homojunction solar cell according to claim 5, characterized in that: The step 3 is specifically as follows: Dissolve Spiro-OMeTAD in chlorobenzene to a concentration of 70-90 mg / mL, then add 15-20 μL of 400-600 mg / mL Li-TFSI / acetonitrile solution, 15-30 μL of 200-500 mg / mL FK209 / acetonitrile solution, and 15-30 μL of tBP solution to obtain a Spiro-OMeTAD solution. The Spiro-OMeTAD solution was spin-coated on the perovskite film at a rotation speed of 1000-5000 rpm and a spin-coating time of 10-45 s to obtain a Spiro-OMeTAD hole transport layer.

10. The in-situ preparation method of a perovskite homojunction solar cell according to claim 5, characterized in that: In step 4, the evaporation chamber pressure is 5×10 -4 Pa below, evaporation rate The electrode thickness is 80-120nm.

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