Back electrode, perovskite photovoltaic cell and laser scribing method thereof

Abstract

The invention relates to the technical field of optoelectronic devices, in particular to a back electrode, a perovskite photovoltaic cell and a laser scribing method thereof. The back electrode comprises a first electrode layer and a second electrode layer which are sequentially stacked and arranged in a contact mode, at least one third electrode layer is arranged in the first electrode layer in the layer thickness direction, and the third electrode layer divides the first electrode layer into a plurality of first sub-electrode layers distributed at intervals; the hardness of the second electrode layer and the hardness of the third electrode layer are both higher than the hardness of the first electrode layer. And / or the brittleness of the second electrode layer and the third electrode layer is higher than the brittleness of the first electrode layer. The back electrode provided by the invention is used in a perovskite photovoltaic cell, can ensure the effect of laser P3 scribing without reducing the overall thickness of the back electrode and the conductivity of the back electrode, effectively reduces the difficulty of laser scribing, improves the effect of laser P3 scribing, and forms laser scribing lines without edge breakage.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of optoelectronic devices, in particular to a back electrode, a perovskite photovoltaic cell and a laser scribing method thereof. BACKGROUND

[0002] The preparation of perovskite cells cannot be separated from laser processing. After depositing the back electrode, the laser etching to remove the back electrode film layer is generally referred to as laser P3 scribing. In order to obtain a good scribing morphology, the selection of a suitable back electrode film layer and the regulation of laser technology are also important factors.

[0003] Laser processing has two scribing directions. One is from top to bottom, and the laser focus directly acts on the back electrode film surface. The other is from bottom to top, and the laser acts on the interface between the glass and the film surface through the glass. Both methods have their own advantages and disadvantages. The former has relatively large scribing edge collapse (commonly known as "crater" morphology) but the process is relatively simple. The latter requires higher laser energy and a narrower process window but the scribing morphology is relatively optimal.

[0004] Currently, the perovskite cell field generally adopts the top-down processing method, and the laser focus directly acts on the film surface. The back electrode absorbs the laser energy and gasifies to form a laser scribing line. This method has a large thermal influence, and the "crater" morphology cannot be avoided. Generally, the line width is increased to avoid the residual film surface from connecting the P3 scribing line slot after lamination and packaging. The laser processing method from bottom to top is limited by the narrow process window, or the back electrode film thickness is reduced to reduce the conductivity of the back electrode, or the P3 line width is increased to reduce the influence of scribing edge collapse on the perovskite cell. It is always difficult to achieve laser scribing without edge collapse and high conversion efficiency of perovskite cells at the same time.

[0005] The back electrode of the perovskite cell is generally copper metal. Copper metal has a soft texture, and a thick thickness seriously affects the laser scribing effect. Reducing the thickness of the back electrode metal film layer will reduce the difficulty of laser scribing, but this processing method will significantly reduce the conversion efficiency of the perovskite cell.

[0006] Therefore, the present application is proposed. SUMMARY

[0007] The first object of the present application is to provide a back electrode for use in the back electrode of a perovskite photovoltaic cell, which can ensure the effect of laser P3 scribing without reducing the conductivity of the back electrode.

[0008] The second object of the present application is to provide a perovskite photovoltaic cell with excellent conversion efficiency.

[0009] The third object of the present application is to provide a laser scribing method for the above-mentioned perovskite photovoltaic cell, which improves the laser P3 scribing effect.

[0010] In order to achieve the above object of the present application, the following technical solutions are adopted:

[0011] The present application provides a back electrode, comprising a first electrode layer and a second electrode layer which are sequentially stacked and in contact, wherein at least one third electrode layer is arranged in the first electrode layer in the thickness direction, and the third electrode layer divides the first electrode layer into a plurality of first sub-electrode layers which are spaced apart.

[0012] The hardness of the second electrode layer and the third electrode layer is higher than that of the first electrode layer; and / or the brittleness of the second electrode layer and the third electrode layer is higher than that of the first electrode layer.

[0013] Further, at least one of the following features (1) to (5) is included:

[0014] (1) The ratio of the sum of the thicknesses of the second electrode layer and the third electrode layer to the thickness of the first electrode layer is 1:(1-5);

[0015] (2) The ratio of the thickness of the third electrode layer to the thickness of the first sub-electrode layer is 1:(1-5);

[0016] (3) The first electrode layer is aluminum or copper;

[0017] (4) The second electrode layer and the third electrode layer are each independently any one of molybdenum, a molybdenum-containing conductive compound, chromium-zirconium-copper, and nickel; the molybdenum-containing conductive compound includes but is not limited to molybdenum disulfide and / or molybdenum dioxide;

[0018] (5) The first electrode layer is copper, and the second electrode layer and the third electrode layer are molybdenum.

[0019] Further, at least one of the following features (1) to (3) is included:

[0020] (1) The thickness of the second electrode layer and the third electrode layer is each independently 5-15 nm;

[0021] (2) The thickness of the first sub-electrode layer is each independently 5-15 nm;

[0022] (3) The thickness of the first electrode layer is 30-80 nm.

[0023] The present application also provides a perovskite photovoltaic cell, comprising a back electrode as described above, a second carrier transport layer, a perovskite layer, a first carrier transport layer, a front electrode and a glass substrate which are sequentially in contact with the back electrode; in the back electrode, the side of the first electrode layer away from the second electrode layer is in contact with the second carrier transport layer.

[0024] The application further provides a laser scribing method of the perovskite photovoltaic cell, and the method for laser P3 scribing of the perovskite photovoltaic cell to be scribed comprises the following steps:

[0025] The laser light source emits etching laser from one side of the glass substrate, and the focal point of the etching laser falls in the film layer of the perovskite photovoltaic cell in sequence through the glass substrate and the front electrode;

[0026] The film layer material is gasified at the focal point of the etching laser, and a blasting shock wave is formed, the blasting shock wave lifts off all the film layers above the front electrode and forms an etching pit, and the front electrode is exposed;

[0027] The etching laser focal point walks along a predetermined track to obtain a plurality of continuous etching pits for forming a P3 scribing line.

[0028] Further, the laser light source used in the laser P3 scribing comprises a green light source.

[0029] Preferably, the wavelength of the laser light source used in the laser P3 scribing is 532nm-556nm.

[0030] Further, the laser P3 scribing comprises positive focal etching.

[0031] And / or, the total energy of the laser P3 scribing is 25w-35w.

[0032] Further, the laser focal point of the laser P3 scribing is located at the interface of the front electrode and the first carrier transport layer.

[0033] And / or, the overlap rate of any two adjacent spots in the laser P3 scribing process is ≤33%.

[0034] Further, the processing speed of the laser P3 scribing is 750-1500mm / s.

[0035] And / or, the laser frequency of the laser P3 scribing is 15-100KHz.

[0036] Further, the laser power of the laser P3 scribing is 425-625mw.

[0037] And / or, the laser spot size of the laser P3 scribing is 50-70μm.

[0038] Compared with the prior art, the application has the following beneficial effects:

[0039] 1、The back electrode for the perovskite photovoltaic cell provided by the application can ensure the effect of laser P3 scribing while not reducing the overall thickness of the back electrode and not reducing the conductivity of the back electrode, effectively reducing the difficulty of laser scribing.

[0040] 2. The laser scribing method of the perovskite photovoltaic cell provided by the application improves the laser P3 scribing effect by using the above-mentioned back electrode and a suitable laser P3 scribing process, forms laser scribing lines without edge collapse, thereby reducing the film layer defects of the perovskite photovoltaic cell and avoiding abnormal conduction of the sub-cell caused by such defects. BRIEF DESCRIPTION OF DRAWINGS

[0041] In order to more clearly illustrate the technical solutions of the embodiments of the application, the following will briefly introduce the drawings needed to be used in the embodiments. It should be understood that the following drawings only show some embodiments of the application, and therefore should not be regarded as a limitation on the scope. For those skilled in the art, other related drawings can also be obtained without creative labor on the basis of these drawings.

[0042] Figure 1 It is a structural schematic diagram of the back electrode of the application.

[0043] Figure 2 It is a laser P3 scribing schematic diagram of the perovskite photovoltaic cell of the application.

[0044] Figure 3 It is a laser P3 scribing effect diagram of Example 4 of the application.

[0045] Figure 4 It is a laser P3 scribing effect diagram of Comparative Example 1 of the application.

[0046] Figure 5 It is a scribing line effect diagram of Examples 4-10 of the application.

[0047] 1-back electrode; 11-first sub-electrode layer; 12-second electrode layer; 13-third electrode layer; 2-second carrier transport layer; 3-perovskite layer; 4-first carrier transport layer; 5-front electrode; 6-glass substrate; 7-laser focal point; 8-etching laser. DETAILED DESCRIPTION

[0048] The technical solutions of the application will be described clearly and completely in combination with the drawings and specific embodiments, but those skilled in the art will understand that the following described embodiments are part of the embodiments of the application, not all the embodiments, and are only used to illustrate the application, and should not be regarded as limiting the scope of the application. Based on the embodiments in the application, all other embodiments obtained by those skilled in the art without creative labor are within the scope of protection of the application. The specific conditions are not indicated in the embodiments, and the conventional conditions or the conditions recommended by the manufacturer are used. The reagents or instruments used are not indicated by the manufacturer, and are all conventional products that can be purchased on the market.

[0049] Reference will be made toFigure 1 In some embodiments of the present application, a back electrode 1 is provided, comprising a first electrode layer and a second electrode layer 12 which are sequentially stacked and arranged in contact, at least one third electrode layer 13 is arranged in the first electrode layer in the thickness direction of the layer, and the third electrode layer 13 divides the first electrode layer into a plurality of first sub-electrode layers 11 which are arranged in intervals;

[0050] The hardness of the second electrode layer 12 and the third electrode layer 13 is higher than the hardness of the first electrode layer; and / or, the brittleness of the second electrode layer 12 and the third electrode layer 13 is higher than the brittleness of the first electrode layer.

[0051] In some embodiments of the present application, the back electrode 1 comprises a back electrode 1 for a perovskite photovoltaic cell.

[0052] The back electrode provided by the present application, when used in a perovskite photovoltaic cell, can ensure the effect of laser P3 scribing while not reducing the overall thickness of the back electrode and not reducing the conductivity of the back electrode, effectively reducing the difficulty of laser scribing.

[0053] In some embodiments of the present application, the back electrode 1 comprises a second electrode layer 12, a first sub-electrode layer 11, a third electrode layer 13 and a first sub-electrode layer 11 which are sequentially stacked.

[0054] In some embodiments of the present application, the ratio of the sum of the thicknesses of the second electrode layer 12 and the third electrode layer 13 to the thickness of the first electrode layer is 1:(1-5); typically but not limitedly, for example, the ratio of the sum of the thicknesses of the second electrode layer 12 and the third electrode layer 13 to the thickness of the first electrode layer can be 1:1, 1:2, 1:3, 1:4, 1:5 or a range value formed by any two of them.

[0055] In some embodiments of the present application, the ratio of the thickness of the third electrode layer 13 to the thickness of the first sub-electrode layer 11 is 1:(1-5); typically but not limitedly, for example, the ratio of the thickness of the third electrode layer 13 to the thickness of the first sub-electrode layer 11 can be 1:1, 1:2, 1:3, 1:4, 1:5 or a range value formed by any two of them.

[0056] In some embodiments of the present application, the first electrode layer is aluminum or copper.

[0057] In some embodiments of the present application, the second electrode layer 12 and the third electrode layer 13 are each independently any one of molybdenum, a conductive compound containing molybdenum, chromium zirconium copper and nickel.

[0058] In some embodiments of the present application, the conductive compound containing molybdenum includes but is not limited to molybdenum disulfide and / or molybdenum dioxide, which exists in a powdery state after etching, has a brittleness greater than that of copper, and does not produce the phenomenon of explosive edge during laser scribing.

[0059] In some embodiments of the present application, the first electrode layer is copper, and the second electrode layer 12 and the third electrode layer 13 are molybdenum.

[0060] The present application inserts a certain thickness of molybdenum into the inside and upper layer of the back electrode without changing the overall thickness of the back electrode, to form a structure of multiple layers of copper-molybdenum stacked in turn, such as copper-molybdenum-copper-molybdenum. Since the overall thickness of the back electrode is not reduced, the overall conductivity of the back electrode does not decrease but is slightly improved due to the introduction of molybdenum metal. Copper metal is relatively soft, and under the condition of thick thickness, it is difficult to form a complete impact wave to lift the copper layer by laser processing, which causes the phenomenon of filament adhesion and "crater" on both sides of the laser scribing line. Molybdenum metal is relatively hard and brittle, and appropriate incorporation into the copper layer can effectively reduce the difficulty of laser scribing. The thicker the copper layer, the more likely it is to cause the phenomenon of edge lifting. The thicker the molybdenum layer, the more likely it is to exceed the scribing capability range of the laser equipment. In addition, due to the high hardness of the molybdenum layer, excessive thickness also affects the blasting degree, and the cost of molybdenum is also high. However, if the molybdenum layer is too thin, it cannot effectively suppress the phenomenon of copper edge lifting and filament adhesion.

[0061] In some embodiments of the present application, the thickness of the second electrode layer 12 and the third electrode layer 13 is independently 5-15 nm. Typically but not limitedly, for example, the thickness of the second electrode layer 12 and the third electrode layer 13 can be independently 5 nm, 6 nm, 7 nm, 8 nm, 9 nm, 10 nm, 11 nm, 12 nm, 13 nm, 14 nm, 15 nm, or a range value formed by any two of them.

[0062] In some embodiments of the present application, the thickness of the second electrode layer 12 and the third electrode layer 13 is the same or different.

[0063] In some embodiments of the present application, the thickness of the first sub-electrode layer 11 is independently 5-15 nm. Typically but not limitedly, for example, the thickness of the first sub-electrode layer 11 can be independently 5 nm, 6 nm, 7 nm, 8 nm, 9 nm, 10 nm, 11 nm, 12 nm, 13 nm, 14 nm, 15 nm, or a range value formed by any two of them.

[0064] In some embodiments of the present application, the thickness of each layer of the first sub-electrode layer 11 is the same or different.

[0065] In some embodiments of the present application, the thickness of the first electrode layer is 30-80 nm. Typically but not limitedly, for example, the thickness of the first electrode layer can be 30 nm, 40 nm, 50 nm, 60 nm, 70 nm, 80 nm, or a range value formed by any two of them.

[0066] Reference is made to Figure 2In some embodiments of the present application, a perovskite photovoltaic cell is also provided, which comprises the back electrode 1 described above, a second carrier transport layer 2, a perovskite layer 3, a first carrier transport layer 4, a front electrode 5 and a glass substrate 6 in contact with the back electrode in sequence; in the back electrode 1, the side of the first electrode layer away from the second electrode layer 12 is in contact with the second carrier transport layer 2. When the first carrier transport layer 4 is an electron transport layer, the second carrier transport layer is a hole transport layer; when the first carrier transport layer 4 is a hole transport layer, the second carrier transport layer is an electron transport layer.

[0067] In some specific embodiments of the present application, a perovskite photovoltaic cell is provided, which comprises an electron transport layer (30-100 nm thick), a perovskite layer (400-800 nm thick), a hole transport layer (20-60 nm thick), an FTO front electrode (100-500 nm thick) and a glass substrate (1-50 mm thick) in contact with the back electrode in sequence; in the back electrode, the side of the first electrode layer away from the second electrode layer is in contact with the electron transport layer.

[0068] Referring to Figure 2 In some embodiments of the present application, a laser scribing method for the perovskite photovoltaic cell described above is also provided, which comprises the following steps:

[0069] The laser light source emits etching laser 8 from one side of the glass substrate 6, and the focal point of the etching laser 8 falls in the film layer of the perovskite photovoltaic cell in sequence through the glass substrate 6 and the front electrode 5;

[0070] The film layer material is vaporized at the focal point of the etching laser 8 and a blasting shock wave is formed, which lifts off all the film layers above the front electrode 5 and forms an etching pit, exposing the front electrode 5;

[0071] The etching laser focal point moves along the predetermined track to obtain a plurality of continuous etching pits for forming a P3 scribe line.

[0072] The laser P3 scribing is to remove the film layers above the front electrode, i.e. to remove the second carrier transport layer, the perovskite layer, the first carrier transport layer and the back electrode, in which the removal of the back electrode is the key.

[0073] The present application adopts a bottom-up laser processing method (i.e. through the glass to irradiate the film layer), the laser is focused on the interface between the glass and the film layer through the glass substrate, the interface is vaporized after absorbing energy, the volume expands rapidly to form a shock wave, which lifts off all the film layers above the front electrode to form a laser scribe line. This process has small thermal influence and is not easy to form a "crater", but the process window is narrow and the control requirements for process parameters are higher.

[0074] In some embodiments of the present application, the laser light source used in the laser P3 scribing includes a green light source.

[0075] In some embodiments of the present application, the wavelength of the laser light source used in the laser P3 scribing is 532nm-556nm; preferably 532nm.

[0076] The laser light source used in the laser P3 scribing of the present application is a picosecond green light with a wavelength of 532nm. On the one hand, the commonly used front electrode material is FTO, which has a low absorption rate in the green light band. The FTO electrode has a good absorption rate of green light above the film layer. Selecting green light with a wavelength of 532nm can more appropriately adjust the laser scribing parameters to ensure that the FTO is not damaged and the film layer above it can be removed cleanly. On the other hand, compared with nanosecond laser, picosecond laser with shorter pulse width has the advantages of high peak power and short laser action time. In the process of laser etching, picosecond laser can quickly vaporize and evaporate the material, reduce the heat diffusion around the scribing line, and can achieve almost no thermal influence, realizing laser "cold processing".

[0077] In some embodiments of the present application, the laser P3 scribing includes positive focal etching.

[0078] In some embodiments of the present application, the total energy of the laser P3 scribing is 25w-35w; typically but not limitedly, for example, the total energy of the laser P3 scribing can be 25w, 30w, 35w or a range value composed of any two of them.

[0079] In some embodiments of the present application, the laser focal point 7 of the laser P3 scribing is located at the interface between the front electrode 5 and the first carrier transport layer 4.

[0080] In some embodiments of the present application, the overlap rate of any two adjacent light spots in the laser P3 scribing process is ≤33%; preferably, the overlap rate of any two adjacent light spots in the laser P3 scribing process is 17%-25%.

[0081] In some embodiments of the present application, the processing rate of the laser P3 scribing is 750-1500mm / s; typically but not limitedly, for example, the processing rate of the laser P3 scribing can be 750mm / s, 900mm / s, 1100mm / s, 1300mm / s, 1500mm / s or a range value composed of any two of them; preferably 1100-1300mm / s.

[0082] In some embodiments of the present application, the laser frequency of the laser P3 scribing is 15-100 KHz; typically but not limitedly, for example, the laser frequency of the laser P3 scribing can be 15 KHz, 30 KHz, 50 KHz, 70 KHz, 100 KHz, or a range value formed by any two of them; preferably 20-30 KHz.

[0083] In some embodiments of the present application, the laser power of the laser P3 scribing is 425-625 mw; typically but not limitedly, for example, the laser power of the laser P3 scribing can be 425 mw, 450 mw, 475 mw, 500 mw, 525 mw, 550 mw, 575 mw, 600 mw, 625 mw, or a range value formed by any two of them.

[0084] In some embodiments of the present application, the laser spot size of the laser P3 scribing is 50-70 μm; preferably 55-65 μm.

[0085] The overlap rate of the laser P3 scribing is controlled by the processing speed and frequency, and the spot interval is obtained by dividing the processing speed by the frequency, and an overlap rate of not more than 1 / 3 can achieve a better scribing effect.

[0086] For a pure copper film layer back electrode, a high overlap rate of laser scribing has a better effect, a high frequency is beneficial to reduce the filament adhesion phenomenon, and a low frequency will cause the filament adhesion phenomenon to be serious. However, for the laser scribing of the back electrode of the present application, a low overlap rate of laser scribing can obtain a "no crater" laser scribing line, and the above process parameters are not easy to have a "crater" morphology.

[0087] The laser scribing method of the perovskite photovoltaic cell provided by the present application optimizes the laser P3 scribing effect by using the above-mentioned back electrode and suitable laser P3 scribing process, forms a laser scribing line without edge collapse, thereby reducing the film layer defects of the perovskite photovoltaic cell, and avoiding the abnormality of the sub-cell conduction caused by such defects.

[0088] Example 1

[0089] The back electrode 1 provided in this embodiment includes a first electrode layer and a second electrode layer 12 which are sequentially and contactingly arranged, a third electrode layer 13 is arranged in the first electrode layer in the thickness direction, and the third electrode layer 13 divides the first electrode layer into a plurality of first sub-electrode layers 11 which are spaced apart; wherein the two first sub-electrode layers 11 are both copper, have equal thickness and the thickness is 15 nm, the second electrode layer 12 is molybdenum and has a thickness of 5 nm, and the third electrode layer 13 is molybdenum and has a thickness of 5 nm.

[0090] The preparation method of the back electrode 1 provided in this embodiment includes the following steps:

[0091] A substrate is provided, which can be an electron transport layer or a hole transport layer, and a 15-nm copper film layer, a 5-nm molybdenum film layer, a 15-nm copper film layer, and a 5-nm molybdenum film layer are sequentially deposited on the substrate by a vapor phase method.

[0092] Embodiment 2

[0093] The back electrode 1 provided in this embodiment includes a first electrode layer and a second electrode layer 12 which are sequentially and in contact stacked, and a third electrode layer 13 is arranged in the first electrode layer in the layer thickness direction, and the third electrode layer 13 divides the first electrode layer into a plurality of first sub-electrode layers 11 which are spaced apart; wherein the two first sub-electrode layers 11 are both copper, have equal thicknesses, and the thickness is 15 nm, the second electrode layer 12 is molybdenum and has a thickness of 15 nm, and the third electrode layer 13 is molybdenum and has a thickness of 15 nm.

[0094] The preparation method of the back electrode 1 provided in this embodiment is referred to Embodiment 1.

[0095] Embodiment 3

[0096] The back electrode 1 provided in this embodiment includes a first electrode layer and a second electrode layer 12 which are sequentially and in contact stacked, and a third electrode layer 13 is arranged in the first electrode layer in the layer thickness direction, and the third electrode layer 13 divides the first electrode layer into a plurality of first sub-electrode layers 11 which are spaced apart; wherein the two first sub-electrode layers 11 are both copper, have equal thicknesses, and the thickness is 25 nm, the second electrode layer 12 is molybdenum and has a thickness of 5 nm, and the third electrode layer 13 is molybdenum and has a thickness of 5 nm.

[0097] The preparation method of the back electrode 1 provided in this embodiment is referred to Embodiment 1.

[0098] Embodiments 4-10

[0099] The perovskite photovoltaic cell provided in this embodiment has the structure: including the back electrode 1 in Embodiment 1, an electron transport layer (thickness of 60 nm), a perovskite layer 3 (thickness of 650 nm), a hole transport layer (thickness of 30 nm), an FTO front electrode (thickness of 100 nm), and a glass substrate 6 (thickness of 20 mm) which are sequentially in contact with the back electrode 1; wherein the first electrode layer of the back electrode 1 is in contact with the electron transport layer on the side away from the second electrode layer 12.

[0100] The laser scribing method of the perovskite photovoltaic cell provided in this embodiment includes the following steps:

[0101] The laser P3 scribing is performed on the perovskite photovoltaic cell to be scribed; the method for performing laser P3 scribing on the perovskite photovoltaic cell to be scribed comprises: a laser light source (a green light source with a wavelength of 532 nm) emits etching laser 8 from one side of the glass substrate 6, and the focus of the etching laser 8 falls in the film layer of the perovskite photovoltaic cell in turn through the glass substrate 6 and the front electrode 5 (the laser focus 7 is located at the interface between the front electrode 5 and the hole transport layer);

[0102] The film layer material is vaporized at the focus of the etching laser, and a blasting shock wave is formed, which lifts off all the film layers above the front electrode 5 and forms an etching pit, exposing the front electrode 5;

[0103] The etching laser focus moves along a predetermined track to obtain a plurality of continuous etching pits for forming a P3 scribe line.

[0104] In Table 1, the overlap rate is the overlap rate of any two adjacent light spots in the laser P3 scribing process; the number of times is the number of times of generating a scribe line; and the offset distance is the offset distance of the laser spot.

[0105] Table 1

[0106]

[0107] Examples 11-12

[0108] The perovskite photovoltaic cell and the laser scribing method thereof provided in this example refer to Example 10; the only difference is that the back electrode of Example 1 is replaced by the back electrode of Example 2 and the back electrode of Example 3, respectively.

[0109] Example 13

[0110] The back electrode 1 provided in this example refers to Example 1; the only difference is that both of the first sub-electrode layers 11 are aluminum, and the thicknesses are equal and are 15 nm.

[0111] Example 14

[0112] The back electrode 1 provided in this example refers to Example 1; the only difference is that the second electrode layer and the third electrode layer are replaced by equal-thickness molybdenum disulfide instead of a molybdenum layer.

[0113] Comparative Example 1

[0114] The perovskite photovoltaic cell provided in this comparative example comprises a back electrode, an electron transport layer, a perovskite layer, a hole transport layer, an FTO front electrode and a glass substrate which are in contact in turn; wherein the back electrode is a copper layer with a thickness of 30 nm; the electron transport layer, the perovskite layer, the hole transport layer, the FTO front electrode and the glass substrate are the same as those of Example 4.

[0115] The laser scribing method for the perovskite photovoltaic cell provided in this comparative example refers to Example 4, except that the laser P3 scribing parameters are as follows: total energy of 30W, overlap rate of 20%, processing speed of 1200mm / s, frequency of 25KHz, power of 525mw, spot size of 60μm, number of scribings of 2, and offset distance of 48um.

[0116] Experimental Example 1

[0117] The scribing effect diagram of the back electrode in Example 4 is shown below. Figure 3 As shown; where, Figure 3 Image a is a two-dimensional image of the scribing effect (i.e., a top view from the second electrode layer side). Figure 3 Figure b shows a 3D image of the scribing effect. The scribing effect of the back electrode in Comparative Example 1 is shown below. Figure 4 As shown; where, Figure 4 Image a is a two-dimensional image of the scribing effect (i.e., a top view from the second electrode layer side). Figure 4 Image b is a 3D representation of the scratching effect.

[0118] from Figure 3 and Figure 4 As can be seen, when the back electrode is only a copper layer, due to the large thickness of the back electrode and the softness and high ductility of copper, the edges of the copper layer will curl upwards during the explosion, resulting in irregular and burr-like edges on the etched pits. However, by separating the thick copper layer with molybdenum, multiple thinner copper layers can be formed, and each copper layer is covered with a harder molybdenum layer. When the copper is exploded, the upward curling tendency at the edges is reduced due to the thinner copper layers. Combined with the suppressive effect of the molybdenum layer, this significantly reduces or even eliminates the upward curling phenomenon at the edges of the copper layer.

[0119] The scribing lines in Examples 4-10 are as follows Figure 5 As shown; Figure 5 The scribing lines in the text, from top to bottom, are Example 4, Example 5, Example 6, Example 7, Example 8, Example 9, and Example 10.

[0120] from Figure 5 It can be seen that using the parameters of Examples 4 to 10, better etched pits can be obtained, that is, the edges of the etched pits are relatively regular, compared to Figure 3The scheme of using only copper as the back electrode has obvious effect improvement. Using the parameters of laser P3 scribing of Example 4, the frequency of scribing is too large, and the overlapping degree of the light spot is too high, so the efficiency is low and the power consumption is large. Using the parameters of laser P3 scribing of Examples 5-8, the spacing of the light spot during scribing is too large, and the purpose is to observe the edge morphology of each etching pit. Obviously, when the laser power is in the range of 325-625 mw, etching pits with good edge morphology can be obtained, and no back electrode eversion and warping phenomenon is found at the etching pit, which proves the advantage of forming the back electrode by the overlapping mode of copper and molybdenum in turn. Using the parameters of laser P3 scribing of Examples 9 and 10, complete P3 scribing is carried out, and it can be obviously seen that P3 is feasible and has regular edge morphology without warping.

[0121] Finally, it should be noted that: the above examples are only used to illustrate the technical solutions of the present application, and not to limit it; although the present application has been described in detail with reference to the foregoing examples, those skilled in the art should understand that: it can still modify the technical solutions recorded in the foregoing examples, or make equivalent replacement for part or all of the technical features; and these modifications or replacements do not make the essence of the corresponding technical solution deviate from the scope of the technical solutions of the embodiments of the present application.

Claims

1. A back electrode, characterized by The back electrode comprises a first electrode layer and a second electrode layer which are sequentially stacked in contact, at least one third electrode layer is arranged in the first electrode layer in the thickness direction, and the third electrode layer divides the first electrode layer into a plurality of first sub-electrode layers which are spaced apart; The hardness of the second electrode layer and the third electrode layer is higher than that of the first electrode layer, and / or the brittleness of the second electrode layer and the third electrode layer is higher than that of the first electrode layer.

2. The back electrode of claim 1, wherein At least one of the following features (1) to (5) is included; (1) The ratio of the sum of the thicknesses of the second electrode layer and the third electrode layer to the thickness of the first electrode layer is 1:(1-5); (2) The ratio of the thickness of the third electrode layer to the thickness of the first sub-electrode layer is 1:(1-5); (3) The first electrode layer is aluminum or copper; (4) The second electrode layer and the third electrode layer are each independently any one of molybdenum, a molybdenum-containing conductive compound, chromium-zirconium-copper, and nickel; (5) The first electrode layer is copper, and the second electrode layer and the third electrode layer are molybdenum.

3. The back electrode of claim 1, wherein At least one of the following features (1) to (3) is included; (1) The thickness of the second electrode layer and the third electrode layer is independently 5-15 nm; (2) The thickness of the first sub-electrode layer is independently 5-15 nm; (3) The thickness of the first electrode layer is 30-80 nm.

4. A perovskite photovoltaic cell, characterized in that, The back electrode comprises a first electrode layer and a second electrode layer which are sequentially stacked in contact, at least one third electrode layer is arranged in the first electrode layer in the thickness direction, and the third electrode layer divides the first electrode layer into a plurality of first sub-electrode layers which are spaced apart; 5. The laser scribing method of a perovskite photovoltaic cell according to claim 4, characterized in that, The method for laser P3 scribing of a perovskite photovoltaic cell to be scribed comprises: A laser light source emits etching laser from one side of a glass substrate, and the focus of the etching laser falls in the film layer of the perovskite photovoltaic cell in sequence through the glass substrate and the front electrode; The film layer material is gasified at the focus of the etching laser and a blasting shock wave is formed, the blasting shock wave lifts off all the film layers above the front electrode and forms an etching pit, and the front electrode is exposed; The etching laser focus moves along a predetermined track to obtain a plurality of continuous etching pits for forming a P3 scribe line.

6. The method of laser scribing of a perovskite photovoltaic cell according to claim 5, characterized in that, The laser light source used in the laser P3 scribing comprises a green light source; Preferably, the wavelength of the laser light source used in the laser P3 scribing is 532-556 nm.

7. The method of laser scribing of a perovskite photovoltaic cell according to claim 5, characterized in that, The laser P3 scribing comprises positive focus etching; And / or, the total energy of the laser P3 scribing is 25-35 w.

8. The method of laser scribing of a perovskite photovoltaic cell according to claim 5, characterized in that, The laser focus of the laser P3 scribing is located at the interface between the front electrode and the first carrier transport layer; And / or, the overlap rate of any two adjacent spots during the laser P3 scribing is ≤33%.

9. The method of laser scribing of perovskite photovoltaic cells according to claim 5, characterized in that, The processing speed of the laser P3 scribing is 750-1500 mm / s; And / or, the laser frequency of the laser P3 scribing is 15-100 KHz.

10. The method of laser scribing of a perovskite photovoltaic cell according to claim 5, characterized in that, The laser power of the laser P3 scribing is 425-625 mw; And / or, the laser spot size of the laser P3 scribing is 50-70 μm.

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