Lecdylcholine-doped nickel oxide hole transport layer, preparation method thereof and solar cell

Abstract

The invention discloses a lecithin-doped nickel oxide hole transport layer, a preparation method thereof and a solar cell, and belongs to the technical field of new photovoltaic materials. The lecithin-doped nickel oxide hole transport layer is obtained by uniformly dispersing lecithin in the nickel oxide hole transport layer; and the molar ratio of the lecithin to the nickel oxide hole transport layer is (0.0001-1): 1. According to the invention, after lecithin is doped in the nickel oxide hole transport layer, the conductivity of nickel oxide can be significantly improved, a channel is provided for carrier transport, and the carrier transport resistance is reduced; meanwhile, the rough morphology of the nickel oxide is improved, the interface energy barrier between the nickel oxide and the perovskite layer is reduced, the non-radiative recombination loss is reduced, and the open-circuit voltage of the cell is improved; in addition, the interface between the nickel oxide and the perovskite can be improved, and a uniform and large-size perovskite thin film can be formed; when the lecithin-doped nickel oxide hole transport layer is used for preparing a solar cell, the stability and performance of the cell can be improved.

Description

Technical Field

[0001] The present application belongs to the technical field of new photovoltaic materials, and specifically relates to a lecithin-doped nickel oxide hole transport layer and a preparation method thereof, and a solar cell. Background Art

[0002] Faced with the growing global energy demand and the limitations of traditional fossil fuels, it is urgent to seek clean, renewable new energy. Traditional solar cells (such as crystalline silicon cells) have problems such as high cost, limited efficiency, and environmental pollution, which make it difficult to meet the needs of future energy development. Perovskite solar cells (PSCs), as the third generation of new solar cells, have shown great application potential due to their excellent properties such as adjustable band gap, high absorption coefficient, low temperature coefficient, thinness and flexibility, and have become a research hotspot in the field of photovoltaic materials.

[0003] Compared with other efficient nip-structured PSCs, the inverted (pin) metal halide PSCs have a photoelectric conversion efficiency of up to 26% and better long-term stability under light and thermal stress. Nickel oxide (NiO), as the most commonly used hole transport material in inverted PSCs, has the advantages of low cost, easy preparation, and good stability, and is considered to be one of the most promising hole transport materials.

[0004] However, the existing NiO hole transport layer materials have problems such as poor NiO conductivity and poor interface contact with the perovskite layer, which leads to increased non-radiative recombination losses. Summary of the invention

[0005] The purpose of the present application is to provide a lecithin-doped nickel oxide hole transport layer and its preparation method, and a solar cell, which are used to solve the problems of poor NiO conductivity and increased non-radiative recombination loss caused by poor interface contact between NiO and the perovskite layer in the existing NiO hole transport layer materials.

[0006] In a first aspect, the present application provides a lecithin-doped nickel oxide hole transport layer, wherein the lecithin-doped nickel oxide hole transport layer is obtained by uniformly dispersing lecithin in the nickel oxide hole transport layer; wherein the molar ratio of lecithin to the nickel oxide hole transport layer is (0.0001~1):1.

[0007] In the lecithin-doped nickel oxide hole transport layer provided by the present invention, the molar ratio of lecithin to the nickel oxide hole transport layer can be, for example, 0.0001:1, 0.0005:1, 0.001:1, 0.005:1, 0.01:1, 0.05:1, 0.1:1, 0.3:1, 0.5:1, 0.7:1, 1:1 or other ratios within this range.

[0008] In the present invention, the inventors have found that after doping lecithin into the nickel oxide hole transport layer, the conductivity of nickel oxide can be significantly improved, while the interface contact with the perovskite layer is improved and the non-radiative recombination loss is reduced.

[0009] In some embodiments, the lecithin comprises hydrogenated lecithin having a structure as shown in the following formula (1):

[0010] In the present invention, the inventors further discovered that the use of hydrogenated lecithin doping can improve the conductivity of the nickel oxide hole transport layer, increase the work function of nickel oxide, and make it have a better energy level match with perovskite, thereby achieving better charge transfer. In addition, hydrogenated lecithin helps to disperse nickel oxide nanoparticles, so that it forms a uniform and dense nickel oxide film, improves the interface contact with perovskite, and is conducive to the crystal growth of perovskite. And N in hydrogenated lecithin + and [PO4] - ions and uncoordinated Pb in perovskite 2+ The interaction between the two passivates the defects of the buried interface. After the above action, the photovoltaic performance and stability of the hole transport layer are greatly improved.

[0011] In a second aspect, the present invention provides a method for preparing a lecithin-doped nickel oxide hole transport layer as described above, comprising the following steps: providing a nickel oxide precursor solution and a lecithin solution respectively; mixing the nickel oxide precursor aqueous solution and the lecithin organic solution to obtain a doping solution; spreading the doping solution on a conductive substrate layer, and obtaining a lecithin-doped nickel oxide hole transport layer after annealing.

[0012] In the present invention, the preparation method of the lecithin-doped nickel oxide hole transport layer is simple, the raw materials used are cheap and easily available, and large-scale industrial production is convenient; in addition, the prepared lecithin-doped nickel oxide hole transport layer has high electrical conductivity and forms a good interface contact with the perovskite layer, which is beneficial to reducing interface defects and promoting carrier extraction.

[0013] In some embodiments, the nickel oxide precursor solution is obtained by dissolving nickel oxide nanoparticles in deionized water, and the concentration of the nickel oxide precursor solution is 0.01~50mM, for example, it can be 0.01mM, 1mM, 5mM, 10mM, 20mM, 30mM, 40mM, 50mM or other values ​​within this range.

[0014] In some embodiments, the preparation of nickel oxide nanoparticles comprises the following steps: dissolving a nickel source in deionized water, and using an alkaline solution to adjust the pH value of the solution to 6.5-11, for example, 6.5, 7, 8, 9, 10, 11 or other values ​​within the range; after stirring the reaction and standing, filtering the solution, washing, drying and calcining the resulting precipitate to obtain nickel oxide nanoparticles.

[0015] In some embodiments, in the preparation process of nickel oxide nanoparticles, the nickel source includes nickel nitrate hexahydrate, and the alkali solution includes ammonia water and / or sodium hydroxide; the stirring reaction step specifically includes: the stirring reaction time is 5 to 60 minutes, for example, it can be 5 minutes, 10 minutes, 20 minutes, 30 minutes, 40 minutes, 50 minutes, 60 minutes or other values ​​within the range; the standing step specifically includes: the standing time is 0.1 to 5 hours, for example, it can be 0.1 hours, 0.5 hours, 1 hours, 2 hours, 3 hours, 4 hours, 5 hours or other values ​​within the range; the drying step specifically includes: at a temperature of 50 to 130 degrees Celsius (for example, it can be 5 The calcining step specifically comprises: calcining for 0.5-4h, for example, 0.5h, 1h, 2h, 3h, 4h or other values ​​within the range at a temperature of 220-350°C (for example, 220°C, 240°C, 260°C, 280°C, 300°C, 320°C, 350°C or other values ​​within the range).

[0016] In some embodiments, the lecithin solution is obtained by dissolving lecithin in an organic solvent, and the concentration of the lecithin solution is 0.0001~10mM, for example, it can be 0.0001mM, 0.001mM, 0.01mM, 0.1mM, 1mM, 5mM, 10mM or other values ​​within this range; wherein the organic solvent is selected from at least one of methanol, ethanol, ethylene glycol, isopropanol, n-butanol and n-hexanol.

[0017] In some embodiments, during the preparation of the doping solution, the molar ratio of lecithin to the nickel oxide precursor in the doping solution is (0.0001~1):1, for example, it can be 0.0001:1, 0.0005:1, 0.001:1, 0.005:1, 0.01:1, 0.05:1, 0.1:1, 0.3:1, 0.5:1, 0.7:1, 1:1 or other ratios within this range.

[0018] In some embodiments, during the preparation of the lecithin-doped nickel oxide hole transport layer, spreading is selected from at least one of spin coating, spray coating, chemical bath deposition, coating and printing.

[0019] In some embodiments, in the preparation process of the lecithin-doped nickel oxide hole transport layer, the annealing step specifically includes: at a temperature of 60 to 300°C, for example, 60°C, 100°C, 150°C, 200°C, 250°C, 300°C or other values ​​within the range; annealing for 5 to 150 minutes, for example, 5 minutes, 10 minutes, 20 minutes, 50 minutes, 80 minutes, 100 minutes, 150 minutes or other values ​​within the range.

[0020] In a third aspect, the present invention provides a solar cell comprising a conductive substrate layer, and a hole transport layer, a perovskite light absorption layer, an electron transport layer, a blocking layer and a metal electrode layer stacked in sequence on the conductive substrate layer; wherein the hole transport layer comprises any one of the above-mentioned lecithin-doped nickel oxide hole transport layers.

[0021] In some preferred embodiments, the solar cell comprises an inverted perovskite solar cell.

[0022] The beneficial effects of the present application are as follows: different from the prior art, the present invention can significantly improve the conductivity of nickel oxide after doping lecithin in the nickel oxide hole transport layer, provide a channel for the transmission of carriers, and reduce the transmission resistance of carriers; at the same time, improve the rough morphology of nickel oxide, reduce the interface energy barrier between nickel oxide and perovskite layer, reduce non-radiative recombination losses, and improve the open circuit voltage of the battery; in addition, it can also improve the interface between nickel oxide and perovskite, which is conducive to the formation of a uniform, large-sized and dense perovskite film; when the lecithin-doped nickel oxide hole transport layer is used to prepare solar cells, the stability and performance of the battery can be improved. BRIEF DESCRIPTION OF THE DRAWINGS

[0023] Figure 1 It is a schematic diagram of the structure of an inverted perovskite solar cell in the present invention; Figure 2 The SEM images of the perovskite films prepared in Example 5 and Comparative Example 2 of the present invention; Figure 3 This is a time-resolved photoluminescence lifetime result diagram of the perovskite film prepared in Example 5 and Comparative Example 2 of the present invention; Figure 4 1 is an efficiency evolution diagram of the inverted perovskite solar cell prepared in Example 1 and Comparative Example 1 of the present invention; The meanings of the reference numerals are as follows: 1: conductive substrate layer; 2: hole transport layer; 3: perovskite light absorption layer; 4: electron transport layer; 5: blocking layer; 6: metal electrode layer. DETAILED DESCRIPTION

[0024] The following will be combined with the embodiments of the present application to clearly and completely describe the technical solutions in the embodiments of the present application. Obviously, the described embodiments are only part of the embodiments of the present application, not all of the embodiments. Based on the embodiments in the present application, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of this application.

[0025] The experimental methods without specific conditions in the examples are usually carried out according to conventional conditions and conditions described in the manual, or according to conditions recommended by the manufacturer. The general equipment, materials, reagents, etc. used are all available from commercial channels unless otherwise specified.

[0026] See also Figure 1 , which is a schematic structural diagram of the inverted perovskite solar cell in the present invention. Specifically, the inverted perovskite solar cell includes: a conductive substrate layer 1, and a hole transport layer 2, a perovskite light absorbing layer 3, an electron transport layer 4, a barrier layer 5 and a metal electrode layer 6 stacked in sequence on the conductive substrate layer 1.

[0027] Example 1 A method for preparing a lecithin-doped nickel oxide hole transport layer comprises the following steps: 1) Dissolve 0.2 mol of nickel nitrate hexahydrate in 20 mL of deionized water to obtain a dark green solution, and stir continuously with a magnetic stirrer; then add ammonia water dropwise to the solution, and use a pH meter to detect the pH value of the solution to make the pH value 8.5, and then continue to stir for 20 minutes. After standing for 1 hour, filter to obtain a light green powder precipitate, wash the light green powder precipitate three times with deionized water, and dry it at a temperature of 80°C for 10 hours; then calcine the dried green powder at a temperature of 270°C for 2 hours to obtain dark black nickel oxide nanoparticles; 2) dissolving the nickel oxide nanoparticles obtained in step 1) in deionized water to a concentration of 20 mg / mL, and then shaking in an oscillator for at least 2 hours to obtain a nickel oxide precursor solution after the nanoparticles are fully dissolved; dissolving hydrogenated lecithin in methanol to a concentration of 5 mg / mL, and then shaking in an oscillator for at least 2 hours to obtain a hydrogenated lecithin solution after the nanoparticles are fully dissolved; 3) 1 mL of the nickel oxide precursor solution prepared in step 2) and 20 μL of the hydrogenated lecithin solution prepared in step 2) were mixed evenly to obtain a doping solution; 4) The doping solution prepared in step 3) was spin coated on the ITO conductive glass substrate using a spin coater at a rotation speed of 2000 rpm for 30 seconds (acceleration of 1000 rpm / s), and then placed on a heating table and annealed at a temperature of 150° C. for 10 minutes to obtain a hydrogenated lecithin-doped nickel oxide hole transport layer.

[0028] Furthermore, the lecithin-doped nickel oxide hole transport layer is used as a material to prepare an inverted perovskite solar cell. Figure 1 As shown in FIG. 1 , ITO conductive glass material is used as the conductive substrate layer 1 (battery positive electrode), hydrogenated lecithin doped NiO material is used as the hole transport layer 2, and Cs 0.05 MA 0.1 FA 0.85 PbI3 material is used as the perovskite light absorption layer 3, C60 material is used as the electron transport layer 4, BCP material is used as the barrier layer 5, and Cu material is used as the metal electrode layer (top electrode).

[0029] The method for preparing the inverted perovskite solar cell comprises the following steps: S1. Prepare a conductive substrate layer 1: The ITO material is ultrasonically cleaned in deionized water and anhydrous ethanol for 20 minutes respectively, and blown dry with dry compressed air to obtain a conductive substrate layer 1 (battery positive electrode) with a thickness of 1.12 mm; S2, preparing a hole transport layer 2: spreading the lecithin-doped nickel oxide material on the conductive base layer 1 by spin coating to obtain a hole transport layer 2 with a thickness of 20 nm; S3, preparation of perovskite light absorbing layer 3: Cs 0.05 MA 0.1 FA 0.85 The PbI3 material is spread on the hole transport layer 2 by spin coating to obtain a perovskite light absorption layer 3 with a thickness of 650 nm; S4, preparing the electron transport layer 4: spreading the C60 material on the perovskite light absorption layer 3 by a vapor deposition method to obtain an electron transport layer 4 with a thickness of 35 nm; S5, preparing the electron blocking layer 5: spreading the BCP material on the electron transport layer 4 by a vapor deposition method to obtain a blocking layer 5 with a thickness of 15 nm; S6. Spread the Cu material on the barrier layer 5 by vapor deposition to obtain a metal electrode layer 6 (top electrode) with a thickness of 150 nm.

[0030] Example 2 The preparation method of the lecithin-doped nickel oxide hole transport layer and the preparation method of the inverted perovskite solar cell in this embodiment are basically the same as those in Example 1, except that in step 3) of the preparation method of the lecithin-doped nickel oxide hole transport layer, the hydrogenated lecithin solution is 10 μL.

[0031] Example 3 The preparation method of the lecithin-doped nickel oxide hole transport layer and the preparation method of the inverted perovskite solar cell in this embodiment are basically the same as those in Example 1, except that in step 3) of the preparation method of the lecithin-doped nickel oxide hole transport layer, the hydrogenated lecithin solution is 30 μL.

[0032] Example 4 The preparation method of the lecithin-doped nickel oxide hole transport layer and the preparation method of the inverted perovskite solar cell in this embodiment are basically the same as those in Example 1, except that in step 3) of the preparation method of the lecithin-doped nickel oxide hole transport layer, the hydrogenated lecithin solution is 40 μL.

[0033] Example 5 The preparation method of the lecithin-doped nickel oxide hole transport layer in this embodiment is basically the same as that in Example 1, except that, in step 4) of the preparation method of the lecithin-doped nickel oxide hole transport layer, the ITO conductive glass substrate is replaced with a soda-lime glass substrate.

[0034] Furthermore, the present embodiment also provides a perovskite film, which includes a conductive substrate layer 1, a hole transport layer 2 and a perovskite light absorption layer 3, and a preparation method thereof includes the following steps: S1. Preparing a conductive substrate layer 1: The soda-lime glass material is ultrasonically cleaned in deionized water and anhydrous ethanol for 20 minutes respectively, and blown dry with dry compressed air to obtain a conductive substrate layer 1 (battery positive electrode) with a thickness of 1.12 mm; S2, preparing a hole transport layer 2: spreading the lecithin-doped nickel oxide material on the conductive base layer 1 by spin coating to obtain a hole transport layer 2 with a thickness of 20 nm; S3, preparation of perovskite light absorbing layer 3: Cs 0.05 MA 0.1 FA 0.85 The PbI3 material is spread on the hole transport layer 2 by spin coating to obtain a perovskite light absorption layer 3 with a thickness of 650 nm.

[0035] Comparative Example 1 The preparation method of the lecithin-doped nickel oxide hole transport layer and the preparation method of the inverted perovskite solar cell in this comparative example are basically the same as those in Example 1, except that the nickel oxide hole transport layer is not doped with hydrogenated lecithin.

[0036] Comparative Example 2 The preparation method of the lecithin-doped nickel oxide hole transport layer and the preparation method of the perovskite film in this comparative example are basically the same as those in Example 5, except that the nickel oxide hole transport layer is not doped with hydrogenated lecithin.

[0037] Performance Testing 1. Photovoltaic performance test of inverted perovskite solar cells The photovoltaic performance of the inverted perovskite solar cells prepared in Examples 1-4 and Comparative Example 1 was tested. Specifically, the test conditions are as follows: the intensity of the simulated sunlight is 100 mW·cm -2 , add an effective area of ​​0.16cm on the top of the battery 2 The test results of the mask are shown in Table 1 below.

[0038] Table 1 Performance test results of inverted perovskite solar cells prepared in Examples 1-4 and Comparative Example 1

[0039] Note: All parameters in the table are positive scan.

[0040] From the data in Table 1, it can be seen that after doping with hydrogenated lecithin, the voltage, short-circuit current and filling factor of the inverted perovskite solar cell have increased, and the efficiency of the inverted perovskite solar cell has also increased significantly. Among them, when the doping amount of the hydrogenated lecithin solution is 20 μL (Example 1), the efficiency of the inverted perovskite solar cell reaches the highest. The above results show that by doping hydrogenated lecithin in the nickel oxide hole transport layer, the conductivity of nickel oxide can be effectively improved, the interface contact between nickel oxide and perovskite can be improved, and the voltage, short-circuit current and filling factor of the battery can be increased, thereby achieving a higher photoelectric conversion efficiency.

[0041] 2. Perovskite film morphology test The perovskite film samples prepared in Example 5 and Comparative Example 2 were subjected to morphology testing (SEM), and the results are as follows: Figure 2 shown.

[0042] from Figure 2 It can be seen that the surface morphology of the perovskite light absorbing layer prepared on the undoped nickel oxide hole transport layer in Comparative Example 2 is poor, the grains and grain boundaries are blurred, and the surface is rough; while the grains in the perovskite light absorbing layer prepared on the hydrogenated lecithin-doped nickel oxide hole transport layer in Example 5 are full and uniform, the grain boundaries are clear, and the surface is smooth; the above results indicate that hydrogenated lecithin doping can improve the interface contact between nickel oxide and perovskite, thereby improving the crystallinity of perovskite.

[0043] 3. Fluorescence lifetime test The perovskite film samples prepared in Example 5 and Comparative Example 2 were subjected to time-resolved photoluminescence lifetime tests. The results are as follows: Figure 3 shown.

[0044] from Figure 3 It can be seen that in Comparative Example 2, since the nickel oxide hole transport layer is not doped with hydrogenated lecithin, there are a large number of defects at the interface between the nickel oxide hole transport layer and the perovskite, and the holes cannot be effectively extracted from the perovskite light absorption layer to the nickel oxide layer, resulting in the fluorescence lifetime of the perovskite film sample prepared in Comparative Example 2 being significantly higher than the perovskite film sample prepared in Example 5 (the nickel oxide hole transport layer is doped with hydrogenated lecithin); the above results show that hydrogenated lecithin doping can improve the conductivity of nickel oxide, reduce interface defects with perovskite, and enhance the hole extraction ability of nickel oxide to perovskite, thereby promoting carrier transport, which is beneficial to improving device performance.

[0045] 4. Stability test of inverted perovskite solar cells The inverted perovskite solar cells prepared in Example 1 and Comparative Example 1 were subjected to a photodegradation test in an unpackaged state. The test conditions were: the light intensity was 100 mW·cm -2 The xenon lamp simulates sunlight. The test results are as follows Figure 4 shown.

[0046] from Figure 4 It can be seen that the photoelectric conversion efficiency of the inverted perovskite solar cell prepared in Example 1 remained above 94% of the initial value in the photodegradation test within 1000h, showing excellent optical stability; while the photoelectric conversion efficiency of the inverted perovskite solar cell prepared in Comparative Example 1 rapidly dropped to about 50% of the initial value in about 600h. The above results show that the introduction of the hydrogenated lecithin-doped nickel oxide hole transport layer in Example 1 significantly improves the photo-induced stability of the inverted perovskite solar cell, which is because the hydrogenated lecithin-doped nickel oxide hole transport layer can effectively inhibit the defect formation and water penetration of the perovskite film, thereby slowing down the photodegradation process.

[0047] In summary, in the present invention, by doping lecithin into the nickel oxide hole transport layer, the conductivity of nickel oxide can be significantly improved, the rough morphology of nickel oxide can be improved, the interface energy barrier between nickel oxide and the perovskite layer can be reduced, and the non-radiative recombination loss can be reduced; and when the lecithin-doped nickel oxide hole transport layer is used to prepare a solar cell, the stability and performance of the battery can be improved.

[0048] It should be noted that the above embodiments all belong to the same inventive concept, and the description of each embodiment has its own focus. For matters that are not described in detail in some embodiments, reference may be made to the description in other embodiments.

[0049] The above-mentioned embodiments only express the implementation methods of the present application, and the descriptions thereof are relatively specific and detailed, but they cannot be understood as limiting the scope of the invention patent. It should be pointed out that, for ordinary technicians in this field, several variations and improvements can be made without departing from the concept of the present application, and these all belong to the protection scope of the present application. Therefore, the protection scope of the patent of the present application shall be subject to the attached claims.

Claims

1. A lecithin-doped nickel oxide hole transport layer, characterized in that: The lecithin-doped nickel oxide hole transport layer is obtained by uniformly dispersing lecithin in the nickel oxide hole transport layer; Wherein, the molar ratio of the lecithin to the nickel oxide hole transport layer is (0.0001~1):

1.

2. The lecithin-doped nickel oxide hole transport layer according to claim 1, characterized in that: The lecithin includes hydrogenated lecithin.

3. A method for preparing a lecithin-doped nickel oxide hole transport layer as claimed in claim 1 or 2, characterized in that: The steps include: respectively providing a nickel oxide precursor solution and a lecithin solution; The nickel oxide precursor aqueous solution and the lecithin organic solution are mixed to obtain a doping solution; The doping solution is spread on the conductive substrate layer, and after annealing, a lecithin-doped nickel oxide hole transport layer is obtained.

4. The method for preparing a lecithin-doped nickel oxide hole transport layer according to claim 3, characterized in that: The nickel oxide precursor solution is obtained by dissolving nickel oxide nanoparticles in deionized water, and the concentration of the nickel oxide precursor solution is 0.01-50 mM.

5. The method for preparing a lecithin-doped nickel oxide hole transport layer according to claim 4, characterized in that: The preparation of the nickel oxide nanoparticles comprises the following steps: The nickel source is dissolved in deionized water, and an alkali solution is used to adjust the pH value of the solution to 6.5-11. After stirring and reacting and standing, the solution is filtered, and the obtained precipitate is washed, dried, and calcined to obtain nickel oxide nanoparticles.

6. The method for preparing a lecithin-doped nickel oxide hole transport layer according to claim 5, characterized in that: In the preparation process of the nickel oxide nanoparticles, the nickel source includes nickel nitrate hexahydrate, and the alkali solution includes ammonia water and / or sodium hydroxide; The stirring reaction step specifically includes: the stirring reaction time is 5 to 60 minutes; The standing step specifically includes: the standing time is 0.1 to 5 hours; The drying step specifically includes: drying at a temperature of 50-130° C. for 1-30 hours; The calcination step specifically includes: calcining at a temperature of 220-350° C. for 0.5-4 hours.

7. The method for preparing a lecithin-doped nickel oxide hole transport layer according to claim 3, characterized in that: The lecithin solution is obtained by dissolving lecithin in an organic solvent, and the concentration of the lecithin solution is 0.0001-10 mM; Wherein, the organic solvent is selected from at least one of methanol, ethanol, ethylene glycol, isopropanol, n-butanol and n-hexanol.

8. The method for preparing a lecithin-doped nickel oxide hole transport layer according to claim 3, characterized in that: In the preparation process of the lecithin-doped nickel oxide hole transport layer, the spreading is selected from at least one of spin coating, spray coating, chemical bath deposition, coating and printing.

9. The method for preparing a lecithin-doped nickel oxide hole transport layer according to claim 3, characterized in that: In the preparation process of the lecithin-doped nickel oxide hole transport layer, the annealing step specifically includes: annealing at a temperature of 60-300° C. for 5-150 minutes.

10. A solar cell, characterized in that: It includes a conductive substrate layer, and a hole transport layer, a perovskite light absorption layer, an electron transport layer, a barrier layer and a metal electrode layer which are sequentially stacked on the conductive substrate layer; Wherein, the hole transport layer comprises the lecithin-doped nickel oxide hole transport layer as described in claim 1 or 2.

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