Nickel oxide film layer and preparation method thereof, perovskite film layer and preparation method thereof, and perovskite photovoltaic cell

Abstract

The invention discloses a nickel oxide film layer and a preparation method thereof, a perovskite film layer and a preparation method thereof, and a perovskite photovoltaic cell, and the preparation method of the nickel oxide film layer comprises the steps: carrying out the plasma surface treatment of a nickel oxide layer, and obtaining the nickel oxide film layer; the process gas for the plasma surface treatment comprises inert gas and reducing gas. During plasma surface treatment, mixed gas of inert gas and reducing gas is selected as process gas, so that the grain size can be increased when the perovskite film layer is guided to grow, the open-circuit voltage, short-circuit current and efficiency of the perovskite cell can be improved, and the service life can be prolonged at the same time.

Description

Technical Field

[0001] The present invention relates to the technical field of perovskite photovoltaic cells, and in particular to a nickel oxide film layer and a preparation method thereof, a perovskite film layer and a preparation method thereof, and a perovskite photovoltaic cell. Background Art

[0002] In the preparation technology of perovskite photovoltaic cells, the inverted pin structure is generally used, and the p-type hole transport layer uses nickel oxide (NiOx) material, which is cheap and has good chemical stability.

[0003] However, in actual applications, the interface defects between the nickel oxide film and the perovskite will act as recombination centers, leading to the recombination of hole carriers and electrons, reducing the output voltage and output current of the battery; 4+ ) Nickel ions and surface defects will also catalyze the decomposition of perovskite. At the same time, due to its hydrophobicity, the nickel oxide film has a low contact energy with the perovskite, resulting in a small grain size of the perovskite layer prepared on the nickel oxide film, which will further reduce the battery output voltage and output current.

[0004] In view of this, the present invention is proposed. Summary of the invention

[0005] The purpose of the present invention is to provide a nickel oxide film layer and a preparation method thereof, a perovskite film layer and a preparation method thereof, and a perovskite photovoltaic cell, which are beneficial to improving the efficiency of the perovskite photovoltaic cell.

[0006] The present invention is achieved in that:

[0007] In a first aspect, the present invention provides a method for preparing a nickel oxide film layer, comprising: obtaining a nickel oxide film layer by a deposition process, and performing plasma surface treatment on the nickel oxide layer to obtain a nickel oxide film layer; the process gas for the plasma surface treatment comprises an inert gas and a reducing gas.

[0008] In an optional embodiment, the volume fraction of the reducing gas in the process gas is 0.1% to 5%;

[0009] and / or, the reducing gas comprises at least one of hydrogen, methane and unsaturated hydrocarbons;

[0010] And / or, the inert gas includes at least one of Ne, Ar and Ke.

[0011] In an optional embodiment, the temperature of the plasma surface treatment is 15°C to 400°C, the time is 10s to 10min, the power is 0.5kW to 5kW, and the pressure of the process gas is 0.2Pa to 20Pa;

[0012] Preferably, the temperature of the plasma surface treatment is 150° C. to 200° C., the time is 1 min to 4 min, the power is 1.8 kW to 4 kW, and the pressure of the process gas is 0.2 Pa to 1 Pa.

[0013] Or, the parameters of the evaporation coating include: the coating rate is Heating power 500W-10kw; preferably, the coating rate is The heating power is 3kw~5kw.

[0014] In an optional embodiment, the nickel oxide layer is deposited and prepared by vacuum coating, evaporation coating, ion coating or sputtering coating.

[0015] In an optional embodiment, the parameters of the sputtering coating include: a coating temperature of 15°C to 400°C, a coating rate of The coating power is 300W to 20kW, the working gas includes inert gas and oxygen, the volume fraction of oxygen in the working gas is less than 20%, the coating gas pressure is 0.05Pa to 5Pa, and the target material is NiOx target material or doped NiOx target material;

[0016] Preferably, the parameters of the sputtering coating include: a coating temperature of 150°C to 200°C, a coating rate of The coating power is 3kW-5kW, the volume fraction of oxygen in the working gas is 0.5%-2%, the coating gas pressure is 0.3Pa-1Pa, and the target material is NiOx target material or doped NiOx target material.

[0017] In a second aspect, the present invention provides a nickel oxide film layer prepared by the method described in any one of the aforementioned embodiments, comprising a transition layer located on the surface of the nickel oxide film layer; and the content of nickel ions in the 4+ valence state in the transition layer gradually decreases along the direction close to the surface of the nickel oxide film layer;

[0018] And / or, the contact angle between the nickel oxide film layer and the aqueous solution of the perovskite precursor is less than 30°.

[0019] In a third aspect, the present invention provides a method for preparing a perovskite film layer, comprising spreading a perovskite precursor solution on the surface of the nickel oxide film layer described in the aforementioned embodiment, and then annealing to obtain the perovskite film layer.

[0020] In an optional embodiment, the perovskite film layer structure is ABX3, wherein A is a monovalent cation, B is a divalent cation, and X is a halogen anion; preferably, A is selected from at least one of a methylamine group, a formamidine group, and a cesium ion, and B is selected from Pb 2+ and Sn 2+ At least one of, X is selected from I- and Br - At least one of .

[0021] In a fourth aspect, the present invention provides a perovskite film layer prepared by the method described in any one of the aforementioned embodiments, wherein the average grain size of the perovskite is greater than 250 nm.

[0022] In a fifth aspect, the present invention provides a perovskite photovoltaic cell, comprising a substrate, a TCO transparent electrode, the nickel oxide film layer described in the aforementioned embodiment, the perovskite film layer described in the aforementioned embodiment, an electron transport layer and an electrode layer arranged in sequence.

[0023] In an optional embodiment, the substrate comprises at least one of glass, PET, PI and PEN;

[0024] And / or, the TCO transparent electrode includes ITO or FTO;

[0025] And / or, the electron transport layer includes at least one of C60, PCBM, tin oxide and titanium dioxide;

[0026] And / or, the electrode layer includes at least one of gold, silver, copper, copper-based alloy, ITO, and FTO.

[0027] In an optional embodiment, the TCO transparent electrode has a thickness of 50 nm to 500 nm;

[0028] And / or, the nickel oxide film layer has a thickness of 5nm to 100nm;

[0029] And / or, the perovskite film layer has a thickness of 10 nm to 1000 nm;

[0030] And / or, the electron transport layer has a thickness of 5 nm to 100 nm;

[0031] And / or, the electrode layer has a thickness of 50 nm to 1000 nm.

[0032] The present invention has the following beneficial effects:

[0033] During plasma surface treatment, a mixture of inert gas and reducing gas is selected as the process gas. On the one hand, it is beneficial to increase the surface energy of the nickel oxide surface layer, improve the binding energy of nickel oxide and perovskite film layer, reduce the hydrophobicity of nickel oxide and the contact angle with perovskite, and on the other hand, it promotes the recrystallization of nickel oxide surface particles and increases the grain size. These two factors guide the increase in grain size during the growth of the perovskite film layer, which is beneficial to increase the open circuit voltage of the perovskite battery, improve battery efficiency, and increase life.

[0034] Plasma surface treatment can be performed on the nickel oxide layer directly using the nickel oxide coating equipment after the nickel oxide layer is formed without other treatment. This is beneficial for simplifying the process while ensuring the effect of improving efficiency, making it easier to industrialize and apply on a large scale. BRIEF DESCRIPTION OF THE DRAWINGS

[0035] In order to more clearly illustrate the technical solutions of the embodiments of the present invention, the drawings required for use in the embodiments are briefly introduced below. It should be understood that the following drawings only show certain embodiments of the present invention and therefore should not be regarded as limiting the scope. For ordinary technicians in this field, other related drawings can be obtained based on these drawings without creative work.

[0036] Figure 1 Schematic diagram of the structure of the perovskite photovoltaic cell prepared in Example 1;

[0037] Figure 2 The XPS spectra of the nickel oxide film surface in Example 1 and Comparative Example 1;

[0038] Figure 3 The contact angle test results of the nickel oxide film surface in Example 1 and Comparative Example 1;

[0039] Figure 4 These are SEM images of the perovskite film layers prepared in Example 1 and Comparative Example 1.

[0040] Illustration: 1-substrate; 2-TCO transparent electrode; 3-nickel oxide film layer; 4-perovskite film layer; 5-electron transport layer; 6-electrode layer. DETAILED DESCRIPTION

[0041] In order to make the purpose, technical scheme and advantages of the embodiments of the present invention clearer, the technical scheme in the embodiments of the present invention will be described clearly and completely below. If the specific conditions are not specified in the embodiments, they are carried out according to conventional conditions or conditions recommended by the manufacturer. If the manufacturer of the reagents or instruments used is not specified, they are all conventional products that can be purchased commercially.

[0042] An embodiment of the present invention provides a method for preparing a nickel oxide film layer, comprising: obtaining the nickel oxide film layer by a deposition process, and performing plasma surface treatment on the nickel oxide layer to obtain the nickel oxide film layer; the process gas for the plasma surface treatment comprises an inert gas and a reducing gas.

[0043] The introduction of reducing gas into the process gas of plasma surface treatment can change the valence state of Ni ions on the surface of nickel oxide film through the reducing effect of reducing gas, making the surface 4 +The conversion of 4+-valent nickel ions into low-valent nickel ions reduces the probability of the perovskite film being catalyzed by 4+-valent nickel ions, which in turn helps to improve battery efficiency and extend battery life.

[0044] However, if only reducing gases are selected as process gases, nickel ions will be over-reduced, thereby reducing the efficiency of the battery prepared therefrom. Therefore, in the present application, inert gas is also introduced into the process gas for plasma surface treatment. The bombardment of inert ions gives kinetic energy to the nickel oxide surface particles, promotes the migration of nickel oxide surface particles, and promotes the recrystallization of surface grains, which is beneficial to reducing the number of surface defects, reducing the probability of catalytic decomposition of the perovskite layer at the surface defects, and reducing the probability of hole-electron recombination between nickel oxide and the perovskite interface layer, which is beneficial to improving battery efficiency and battery life.

[0045] During plasma surface treatment, a mixture of inert gas and reducing gas is selected as the process gas. On the one hand, it is beneficial to increase the surface energy of the nickel oxide surface layer, improve the binding energy of nickel oxide and perovskite film layer, reduce the hydrophobicity of nickel oxide and the contact angle with perovskite, and on the other hand, it promotes the recrystallization of nickel oxide surface particles and increases the grain size. These two factors guide the increase in grain size during the growth of perovskite film layer 4, which is beneficial to increase the open circuit voltage of perovskite battery, improve battery efficiency and increase life.

[0046] Normally, in order to improve the efficiency of perovskite photovoltaic cells, the nickel oxide film layer can be treated by a solution method, but the uniformity of the nickel oxide film layer treated by the solution method is poor, and pretreatment is required before treatment, and cleaning and other processes are also required after treatment, resulting in a complicated process flow, which limits its large-scale application. In this embodiment, the nickel oxide layer is subjected to plasma surface treatment. After the nickel oxide layer is formed, the nickel oxide layer can be directly subjected to plasma surface treatment using the nickel oxide layer coating equipment without other treatments, which is conducive to simplifying the process flow while ensuring the efficiency improvement effect, and is easier to industrialize and apply on a large scale.

[0047] In an optional embodiment, the volume fraction of the reducing gas in the process gas is 0.1% to 5%; specifically, it can be 0.1%, 0.5%, 1%, 1.5%, 2%, 3%, 4%, 5% or any value between 0.1% and 5%, preferably 0.5% to 2%.

[0048] In this embodiment, if the concentration of the reducing gas is too low, the reduction efficiency of 4+ nickel ions will be reduced. However, if the concentration of the reducing gas is too high, the 4+ nickel ions may be over-reduced to metallic nickel, thereby reducing the performance of the nickel oxide film layer 3 used in the perovskite battery. When the volume fraction of the reducing gas in the process gas is 0.5% to 2%, it is used in the perovskite battery, and the improvement of the efficiency of the perovskite battery is more significant.

[0049] In an optional embodiment, the reducing gas includes at least one of hydrogen, methane and unsaturated hydrocarbons. The unsaturated hydrocarbons may be alkynes, etc., which can maintain a gaseous state during the plasma surface treatment process and have reducing properties. However, in some embodiments, in order to reduce the introduction of impurities into the nickel oxide film layer, hydrogen is preferably used.

[0050] In an optional embodiment, the inert gas includes at least one of Ne, Ar and Ke.

[0051] In an optional embodiment, the temperature of the plasma surface treatment is 15°C to 400°C, specifically 15°C, 50°C, 100°C, 150°C, 160°C, 170°C, 180°C, 190°C, 200°C, 250°C, 300°C, 350°C, 400°C or any value between 15°C and 400°C; the time is 10s to 10min, specifically 10s, 30s, 1min, 90s, 2min, 3min, 4min, 5min, 7min, 10min or any value between 10s and 10min; the power is 0.5kW to 5kW, specifically 0.5kW, 1 The process gas pressure is 0.2Pa-20Pa, specifically 0.2Pa, 0.4Pa, 0.5Pa, 0.6Pa, 0.8Pa, 1Pa, 2Pa, 5Pa, 10Pa, 15Pa, 20Pa or any value between 0.2Pa and 20Pa.

[0052] In specific operation, the prepared nickel oxide film layer can be directly sent into the plasma surface treatment chamber, and the plasma generator used can be selected from one or more composite forms of plasma sources such as linear ion source, Hall source, ICP, CCP, etc., and the temperature, time and gas pressure of the plasma surface treatment are adjusted to adjust the plasma density, treatment depth, treatment rate and reduction degree of tetravalent nickel ions, so as to improve the binding energy of nickel oxide and perovskite film layer, reduce the hydrophobicity of nickel oxide and the contact angle with perovskite, and guide the increase of grain size when the perovskite film layer 4 grows. When the temperature of the plasma surface treatment is 150℃~200℃, the time is 1min~4min, the power is 1.8kW~4kW, and the gas pressure of the process gas is 0.2Pa~1Pa, it is more conducive to improving the efficiency of the battery including the nickel oxide film layer.

[0053] In an optional embodiment, the nickel oxide film layer is deposited and prepared by vacuum coating, evaporation coating, ion coating or sputtering coating.

[0054] In an optional embodiment, the parameters of the sputtering coating include: a coating temperature of 15°C to 400°C, specifically 15°C, 50°C, 100°C, 150°C, 160°C, 170°C, 180°C, 190°C, 200°C, 250°C, 300°C, 350°C, 400°C or any value between 15°C and 400°C; a coating rate of Specifically, it can be or any value between ; the coating power is 300W~20kW, specifically 300W, 1kW, 2kW, 3kW, 4kW, 5kW, 10kW, 15kW, 20kW or any value between 300W and 20kW; the working gas includes inert gas and oxygen, and the volume fraction of oxygen in the working gas is less than 20%, specifically 0.1%, 0.5%, 1%, 1.5%, 2%, 5%, 10%, 15%, 20% or any value less than 20%; the coating gas pressure is 0.05Pa~5Pa, specifically 0.05Pa, 0.1Pa, 0.3Pa, 0.5Pa, 0.7Pa, 0.9Pa, 2Pa, 3Pa, 4Pa, 5Pa or any value between 0.05Pa and 5Pa; the target material is a nickel oxide target material or a doped nickel oxide target material.

[0055] The nickel oxide film layer can be prepared by magnetron sputtering methods such as medium frequency sputtering, DC / pulse sputtering and radio frequency sputtering, or by a superposition of two or more methods. By adjusting the sputtering coating parameters, it is helpful to ensure the adhesion of the nickel oxide film layer to the substrate and the uniformity of the nickel oxide film layer.

[0056] When the sputtering coating parameters include: coating temperature of 150°C to 200°C, coating rate of When the coating power is 3kW to 5kW, the volume fraction of oxygen in the working gas is 0.5% to 2%, the coating pressure is 0.3Pa to 1Pa, and the target material is a nickel oxide target material or a doped nickel oxide target material, it is more conducive to improving the efficiency of the battery including the nickel oxide film layer.

[0057] In an optional embodiment, the parameters of the evaporation coating include: a coating rate of Specifically, it can be or The heating power is 500W-10kw, specifically, it can be 500W, 1kW, 2kW, 3kW, 4kW, 5kW, 10kW or any value between 500W-10kw; adjusting the coating parameters is beneficial to ensure the adhesion of the nickel oxide film layer to the substrate, and the uniformity of the nickel oxide film layer.

[0058] When the parameters of the evaporation coating include: the coating rate is When the heating power is 3kw to 5kw, it is more conducive to improving the efficiency of the battery including the nickel oxide film layer.

[0059] The embodiment of the present invention further provides a nickel oxide film layer prepared by the method described in any one of the above embodiments, comprising a transition layer located on the surface of the nickel oxide film layer; and the content of nickel ions in the 4+ valence state in the transition layer gradually decreases along the direction close to the surface of the nickel oxide film layer;

[0060] And / or, the contact angle between the nickel oxide film layer and the aqueous solution of the perovskite precursor is less than 30°.

[0061] As the plasma surface treatment process proceeds, the 4+ valence nickel ions on the surface of the nickel oxide film layer are gradually reduced, and the treatment depth gradually increases, thereby forming a transition layer in which the 4+ valence nickel ion content gradually decreases along the surface of the nickel oxide film layer. The reduction of 4+ valence nickel ions on the surface of the nickel oxide film layer is beneficial to reducing the probability of the perovskite film layer being catalyzed and decomposed by 4+ valence nickel ions, improving battery efficiency and extending battery life.

[0062] The contact angle between the nickel oxide film layer after plasma surface treatment and the aqueous solution of the perovskite precursor will be smaller than the contact angle between the nickel oxide film layer without plasma surface treatment and the aqueous solution of the perovskite precursor. The aqueous solution of the perovskite precursor may have a certain mass fraction, such as an aqueous solution with a mass fraction of 0.5mmoL / mL to 2mmoL / mL. Although the mass fraction of perovskite in the aqueous solution of the perovskite precursor is relatively low, it will still affect the contact angle between the aqueous solution of the perovskite precursor and nickel oxide to a certain extent. If the nickel oxide film layer is not subjected to plasma surface treatment, the contact angle between the nickel oxide film layer and the aqueous solution with a mass fraction of 0.9mmoL / mL to 1.1mmoL / mL of the perovskite precursor is usually greater than 20°. After plasma surface treatment, the contact angle becomes less than 8°, and the contact angle is significantly reduced.

[0063] The present invention also provides a method for preparing a perovskite film layer, comprising spreading a perovskite precursor solution on the surface of the nickel oxide film layer described in the above embodiment, and then annealing to obtain the perovskite film layer.

[0064] In the embodiment of the present invention, plasma surface treatment of the nickel oxide film layer can improve the binding energy of the nickel oxide and perovskite film layer, reduce the hydrophobicity of nickel oxide, and reduce the contact angle of perovskite. Therefore, when the perovskite film layer is prepared by the solution method, the perovskite precursor solution can be fully contacted with the nickel oxide film layer, which is beneficial to the recrystallization of the perovskite on the surface of the nickel oxide film layer, and promotes the growth of the grain size when the perovskite film layer grows, thereby improving the battery efficiency and life. In an optional embodiment, the perovskite film layer 4 has an ABX3 structure, wherein A is a monovalent cation, B is a divalent cation, and X is a halogen anion;

[0065] Preferably, A is selected from at least one of a methylamine group, a formamidine group and a cesium ion, and B is selected from Pb 2+ and Sn 2+ At least one of, X is selected from I - and Br - At least one of .

[0066] The preparation method of the perovskite film layer 4 includes but is not limited to slit coating and spin coating.

[0067] In a fourth aspect, the present invention provides a perovskite film layer prepared by the method described in any one of the aforementioned embodiments, wherein the average grain size of the perovskite is greater than 250 nm.

[0068] When the nickel oxide film layer is not subjected to plasma surface treatment, the average grain size of the perovskite is less than 200nm. After the plasma surface treatment, the average grain size of the perovskite is greater than 250nm, and the average grain size of the perovskite is significantly increased.

[0069] An embodiment of the present invention further provides a perovskite photovoltaic cell, comprising a substrate 1, a TCO transparent electrode 2, the nickel oxide film layer 3 described in the above embodiment, a perovskite film layer 4, an electron transport layer 5 and an electrode layer 6 arranged in sequence.

[0070] In an optional embodiment, the substrate 1 includes at least one of glass, PET (polyethylene terephthalate), PI (polyimide) and PEN (polyethylene naphthalate);

[0071] And / or, the TCO transparent electrode 2 comprises ITO or FTO, and the preparation method includes but is not limited to physical vapor deposition PVD and chemical vapor deposition CVD;

[0072] And / or, the electron transport layer 5 includes at least one of C60, PCBM, tin oxide, and titanium dioxide; the preparation method includes but is not limited to evaporation and atomic layer deposition ALD;

[0073] And / or, the electrode layer 6 includes at least one of gold, silver, copper, copper-based alloy, ITO, and FTO; the preparation method includes but is not limited to sputtering and evaporation.

[0074] In an optional embodiment, the thickness of the TCO transparent electrode 2 is 50 nm to 500 nm, specifically, it can be 50 nm, 100 nm, 200 nm, 300 nm, 400 nm, 500 nm or any value between 50 nm and 500 nm;

[0075] And / or, the nickel oxide film layer 3 has a thickness of 5 nm to 100 nm, specifically, 5 nm, 10 nm, 20 nm, 40 nm, 60 nm, 80 nm, 100 nm or any value between 5 nm and 100 nm;

[0076] And / or, the perovskite film layer 4 has a thickness of 10 nm to 1000 nm, specifically, 10 nm, 20 nm, 40 nm, 60 nm, 80 nm, 100 nm, 200 nm, 300 nm, 400 nm, 500 nm, 600 nm, 800 nm, 1000 nm or any value between 10 nm and 1000 nm;

[0077] And / or, the thickness of the electron transport layer 5 is 5 nm to 100 nm, specifically, it can be 5 nm, 10 nm, 20 nm, 40 nm, 60 nm, 80 nm, 100 nm or any value between 5 nm and 100 nm;

[0078] And / or, the electrode layer 6 has a thickness of 50 nm to 1000 nm, specifically, can be 50 nm, 60 nm, 80 nm, 100 nm, 200 nm, 300 nm, 400 nm, 500 nm, 600 nm, 800 nm, 1000 nm or any value between 50 nm and 1000 nm.

[0079] The features and performance of the present invention are further described in detail below in conjunction with the embodiments.

[0080] Example 1

[0081] This embodiment provides a method for preparing a perovskite photovoltaic cell, comprising the following steps:

[0082] Cleaning and drying the FTO conductive glass substrate 1;

[0083] The nickel oxide target is mounted on the sputtering cathode, the FTO conductive glass substrate 1 is placed in the sputtering chamber, and the sputtering chamber is evacuated until the vacuum degree of the sputtering chamber is less than 2×10 -4Pa, introduce process gas into the sputtering chamber, the process gas is argon and oxygen, the argon flow rate is 396sccm, the argon oxygen mixed gas flow rate is 400sccm, after the pressure in the chamber is stabilized at 1Pa, turn on the RF sputtering power, the sputtering power is slowly increased to 1kW, and pre-sputtering is performed for 10min to remove impurities on the surface of the nickel oxide target; after the pre-sputtering is completed, heat the chamber temperature to stabilize at 200℃ for deposition, and the deposition rate is The sputtering step is terminated when the thickness of the nickel oxide layer reaches 20 nm;

[0084] Plasma surface treatment was performed on the nickel oxide layer placed in the vacuum chamber. The process gas was a mixture of argon and hydrogen. The argon flow rate was 100 sccm, the hydrogen flow rate was 2 sccm, and the chamber temperature was 200°C. After the pressure in the chamber was stabilized at 1 Pa, the ICP power supply was turned on with a power of 2 kW. The plasma surface treatment time was 2 min.

[0085] A 500nm thick perovskite layer is formed on the surface of the plasma-treated nickel oxide film layer by a slit coating method, and the material of the perovskite layer is MAPbI3 (methylamine lead iodide);

[0086] A 20 nm thick C60 layer is deposited on the surface of the perovskite layer by evaporation, and a 20 nm thick tin oxide layer is deposited by ALD as an electron transport layer 5;

[0087] On the surface of the electron transport layer 5, a 20nm ITO film layer is prepared by radio frequency sputtering, a 30nm ITO film layer is prepared by direct current sputtering, and a 50nm Cu film layer is prepared as an electrode layer 6 to obtain a perovskite photovoltaic cell with a structure as shown below: Figure 1 shown.

[0088] Example 2

[0089] This embodiment provides a perovskite photovoltaic cell, which is different from the preparation method of the perovskite photovoltaic cell provided in Example 1 in that: in the plasma surface treatment step, the argon flow rate in the mixed gas is 100 sccm, and the hydrogen flow rate is 5 sccm.

[0090] Example 3

[0091] This embodiment provides a perovskite photovoltaic cell, which is different from the preparation method of the perovskite photovoltaic cell provided in Example 1 in that: in the plasma surface treatment step, the argon flow rate in the mixed gas is 100 sccm, and the hydrogen flow rate is 0.5 sccm.

[0092] Example 4

[0093] This embodiment provides a perovskite photovoltaic cell, which differs from the preparation method of the perovskite photovoltaic cell provided in Example 1 in that: in the plasma surface treatment step, the chamber temperature is 150°C, and after the air pressure in the chamber is stabilized at 0.2 Pa, the CCP power supply is turned on with a power of 3kw, and the nickel oxide film layer is subjected to plasma surface treatment for 2 minutes.

[0094] Example 5

[0095] The present embodiment provides a perovskite photovoltaic cell, which differs from the preparation method of the perovskite photovoltaic cell provided in Example 1 in that: in the plasma surface treatment step, the chamber heating temperature is 150°C, and after the gas pressure in the chamber is stabilized at 0.5 Pa, the CCP power supply is turned on with a power of 2kw, an argon flow rate of 200sccm, and a hydrogen flow rate of 2sccm, and the NiOx film layer is plasma surface treated for 3 minutes.

[0096] Comparative Example 1

[0097] This comparative example provides a perovskite photovoltaic cell, which differs from the preparation method of the perovskite photovoltaic cell provided in Example 1 in that the perovskite layer is prepared directly after the nickel oxide film layer is prepared by sputtering, and no plasma surface treatment is performed.

[0098] Comparative Example 2

[0099] This comparative example provides a perovskite photovoltaic cell, which is different from the preparation method of the perovskite photovoltaic cell provided in Example 1 in that in the plasma surface treatment step, the argon flow rate in the mixed gas is 102 sccm, and the hydrogen flow rate is 0 sccm.

[0100] Comparative Example 3

[0101] This comparative example provides a perovskite photovoltaic cell, which is different from the preparation method of the perovskite photovoltaic cell provided in Example 1 in that in the plasma surface treatment step, the argon flow rate in the mixed gas is 100 sccm, and the hydrogen flow rate is 10 sccm.

[0102] The XPS spectra of the nickel oxide film surface in Example 1 and Comparative Example 1 are as follows: Figure 2 As shown in the figure, the blue line is the peak position diagram of Ni after fitting. Figure 2It can be seen that the 4+ nickel ion content in the nickel oxide surface film layer that has not been subjected to plasma surface treatment is higher than that in the nickel oxide surface film layer that has been subjected to plasma surface treatment. At the same time, it is shown that the nickel oxide surface layer that has been subjected to plasma surface treatment forms a gradient structure of 4+ nickel ions with the main nickel oxide. This is because the reducing effect of the reducing gas during the plasma surface treatment process reduces the valence state of the 4+ nickel ions. However, as the depth of the nickel ions increases, the difficulty of reduction increases, which reduces the number of internal 4+ nickel ions reduced, forming a concentration gradient structure of 4+ nickel ions.

[0103] The contact angle test results of the perovskite film layer 4 on the surface of the nickel oxide film layer in Example 1 and Comparative Example 1 are as follows: Figure 3 As shown, a precursor solution of the perovskite layer with a concentration of 1 mmol / mL is dropped onto the surface of the nickel oxide layer, and the contact angle of the perovskite precursor liquid on the nickel oxide layer is measured. Figure 3 It can be seen that the contact angle of the perovskite precursor solution on the nickel oxide surface film layer that has not been treated with plasma is 22.3°, which is larger than the contact angle of 6.3° on the nickel oxide surface film layer that has been treated with plasma, indicating that after the plasma surface treatment, the hydrophobicity of the nickel oxide film layer and the perovskite layer is reduced. This may be because the plasma surface treatment increases the surface energy of the nickel oxide surface layer and the binding energy of the nickel oxide and perovskite film layers.

[0104] The SEM images of the perovskite film layer 4 prepared in Example 1 and Comparative Example 1 are as follows: Figure 4 As shown in the figure, after the perovskite layer is formed on the nickel oxide surface that has not been treated with plasma, the average grain size is 185nm, and after the perovskite layer is formed on the nickel oxide surface that has been treated with plasma, the average grain size is 290nm. The grain size of the perovskite layer after being formed on the nickel oxide surface that has been treated with plasma is significantly larger than that of the sample that has not been treated with plasma. This may be because the plasma surface treatment can promote the migration of particles on the nickel oxide surface and promote the recrystallization of the surface grains. At the same time, the plasma surface treatment can improve the hydrophobicity of the perovskite film layer under the NiO and increase the wettability. These two factors promote the increase of the grain size during the growth of the perovskite grains.

[0105] The performance data of the perovskite photovoltaic cells prepared in each embodiment and comparative example are shown in Table 1.

[0106] Table 1

[0107] Voc(V) <![CDATA[Isc(mA / cm 2 )]]> FF(%) PCE(%) Example 1 1.03 21 68.3 14.77329 Example 2 1.02 22 66.7 14.96748 Example 3 1.03 20.5 67.2 14.18928 Example 4 1.01 22 69.4 15.42068 Example 5 1 21 68.7 14.427 Comparative Example 1 0.98 19.8 65.2 12.651408 Comparative Example 2 0.97 18 66 11.5236 Comparative Example 3 0.95 18 64 12.635

[0108] From Table 1: It can be seen from the comparison between the embodiment and comparative example 1 that the nickel oxide film layer that has been surface treated with plasma is used in the perovskite photovoltaic cell, the battery performance parameters such as the battery open circuit voltage, short circuit current, fill factor and efficiency are all higher than those of the sample that has not been surface treated with plasma, indicating that the nickel oxide film layer that has been surface treated with plasma can improve the performance of the perovskite photovoltaic cell.

[0109] It can be seen from Examples 1-3 and Comparative Examples 1-3 that with the increase of the hydrogen content in the process gas in the plasma surface treatment step, the open circuit voltage, short circuit current, fill factor and efficiency of the battery all tend to increase first and then decrease, and have better effects between 0.1% and 5%. However, if the hydrogen concentration is too low or too high, the battery performance will decrease instead of increase.

[0110] By comparing Example 1 with Comparative Examples 4 and 5, it can be seen that adjusting the parameters of the plasma surface treatment step will have an impact on the battery performance, but as long as the parameters are within the range specified in this application, the battery open circuit voltage, short circuit current, fill factor and efficiency can be maintained in a better range.

[0111] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. For those skilled in the art, the present invention may have various modifications and variations. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present invention shall be included in the protection scope of the present invention.

Claims

1. A method for preparing a nickel oxide film, characterized in that: include: A nickel oxide film layer is obtained by a deposition process, and a plasma surface treatment is performed on the nickel oxide layer to obtain a nickel oxide film layer; The process gas for the plasma surface treatment includes an inert gas and a reducing gas.

2. The method for preparing a nickel oxide film according to claim 1, characterized in that: The volume fraction of reducing gas in the process gas is 0.1% to 5%, preferably 0.5% to 2%; and / or, the reducing gas comprises at least one of hydrogen, methane and unsaturated hydrocarbons; And / or, the inert gas includes at least one of Ne, Ar and Ke.

3. The method for preparing a nickel oxide film according to claim 1, characterized in that: The temperature of the plasma surface treatment is 15°C to 400°C, the time is 10s to 10min, the power is 0.5kW to 5kW, and the pressure of the process gas is 0.2Pa to 20Pa; Preferably, the temperature of the plasma surface treatment is 150° C. to 200° C., the time is 1 min to 4 min, the power is 1.8 kW to 4 kW, and the pressure of the process gas is 0.2 Pa to 1 Pa.

4. The method for preparing a nickel oxide film according to claim 1, characterized in that: The nickel oxide layer is deposited and prepared by vacuum coating, evaporation coating, ion coating or sputtering coating.

5. The method for preparing a nickel oxide film according to claim 4, characterized in that: The parameters of the sputtering coating include: coating temperature of 15°C to 400°C, coating rate of The coating power is 300W-20kW, the working gas includes inert gas and oxygen, the volume fraction of oxygen in the working gas is less than 20%, the coating pressure is 0.05Pa-5Pa, and the target material is NiOx target material or doped NiOx target material; preferably, the sputtering coating parameters include: the coating temperature is 150℃-200℃, the coating rate is The coating power is 3kW to 5kW, the volume fraction of oxygen in the working gas is 0.5% to 2%, the coating gas pressure is 0.3Pa to 1Pa, and the target material is NiOx target material or doped NiOx target material; Or, the parameters of the evaporation coating include: the coating rate is Heating power 500W-10kw; preferably, the coating rate is The heating power is 3kw~5kw.

6. A nickel oxide film layer prepared by the method according to any one of claims 1 to 5, characterized in that: It comprises a transition layer located on the surface of the nickel oxide film layer; and the content of nickel ions in the 4+ valence state in the transition layer gradually decreases in a direction close to the surface of the nickel oxide film layer; And / or, the contact angle between the nickel oxide film layer and the aqueous solution of the perovskite precursor is less than 30°.

7. A method for preparing a perovskite film, characterized in that: The method comprises spreading a perovskite precursor solution on the surface of the nickel oxide film layer according to claim 6, and then annealing to obtain the perovskite film layer.

8. The method for preparing a perovskite film according to claim 7, characterized in that: The perovskite film layer structure is ABX3, wherein A is a monovalent cation, B is a divalent cation, and X is a halogen anion; preferably, A is selected from at least one of a methylamine group, a formamidine group, and a cesium ion, and B is selected from Pb 2+ and Sn 2+ At least one of, X is selected from I - and Br - At least one of .

9. A perovskite film prepared by the method of claim 7 or 8, characterized in that: The average grain size of perovskite is greater than 250nm.

10. A perovskite photovoltaic cell, characterized in that: The invention comprises a substrate, a TCO transparent electrode, the nickel oxide film layer according to claim 6, the perovskite film layer according to claim 9, an electron transport layer and an electrode layer which are arranged in sequence.

11. The perovskite photovoltaic cell according to claim 10, characterized in that: The substrate comprises at least one of glass, PET, PI and PEN; And / or, the TCO transparent electrode includes ITO or FTO; And / or, the electron transport layer includes at least one of C60, PCBM, tin oxide and titanium dioxide; And / or, the electrode layer comprises at least one of gold, silver, copper, copper-based alloy, ITO, and FTO; And / or, the TCO transparent electrode has a thickness of 50 nm to 500 nm; And / or, the nickel oxide film layer has a thickness of 5nm to 100nm; And / or, the perovskite film layer has a thickness of 10 nm to 1000 nm; And / or, the electron transport layer has a thickness of 5 nm to 100 nm; And / or, the electrode layer has a thickness of 50 nm to 1000 nm.

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