Preparation method of solar cell and solar cell

Abstract

The invention discloses a preparation method of a solar cell and the solar cell. The preparation method comprises the following steps: a main grid line of at least one main surface of the solar cell is formed by curing and printing low-temperature slurry, and other grid lines of the solar cell are formed by high-temperature sintering and printing high-temperature slurry except the main grid line formed by curing the low-temperature slurry. And the step of curing the printed low-temperature slurry is performed after the step of forming other grid lines. According to the scheme, the main grid lines on at least one main surface of the solar cell can be prevented from being in contact with the doping layer, so that the open voltage loss of the solar cell is effectively reduced.

Description

Technical Field

[0001] The invention relates to a method for preparing a solar cell and the solar cell. Background Art

[0002] At present, for solar cells with fine grid lines and main grid lines, the fine grid lines and main grid lines are generally printed and sintered simultaneously. In the existing method of synchronously printing fine grid lines and main grid lines, the fine grid lines and main grid lines are generally made of high-temperature slurry containing glass powder components, so that the high-temperature slurry can pierce and destroy the area of ​​the passivation anti-reflection layer it contacts during the sintering process, so as to achieve the purpose of forming an ohmic contact between the fine grid lines and the doped layer. However, the existing method of synchronous printing and sintering inevitably causes the main grid lines to contact the doped layer, resulting in metal recombination, which causes the solar cell to have a relatively high opening voltage loss. Summary of the invention

[0003] In view of this, the present invention provides a method for preparing a solar cell and a solar cell, which prevents a main grid line on at least one main surface of the solar cell from contacting a doping layer, so as to effectively reduce the opening voltage loss of the solar cell.

[0004] In order to solve the above technical problems, the present invention provides the following technical solutions:

[0005] In a first aspect, the present invention provides a method for preparing a solar cell, comprising:

[0006] Step A: forming a main grid line on at least one main surface of a solar cell by curing the printed low-temperature paste, wherein:

[0007] In addition to the main grid lines formed by curing the low-temperature paste, other grid lines of the solar cell are formed by high-temperature sintering of printed high-temperature paste, and the step of curing the printed low-temperature paste is after the step of forming other grid lines.

[0008] In a second aspect, an embodiment of the present invention provides a solar cell prepared by the preparation method provided by the embodiment of the first aspect, comprising: a main grid line formed by curing and printing a low-temperature paste and other grid lines formed by high-temperature sintering and printing a high-temperature paste, wherein:

[0009] The main grid line formed by the low-temperature slurry is located on at least one main surface of the solar cell;

[0010] Other grid lines formed by the high temperature paste are distributed on two main surfaces of the solar cell;

[0011] The main gate lines formed by the low-temperature slurry are formed after the other gate lines are formed.

[0012] The technical solution of the first aspect of the above invention has the following advantages or beneficial effects:

[0013] 1. The method for preparing a solar cell provided in an embodiment of the present invention forms a main grid line on at least one main surface of a solar cell by curing a printed low-temperature paste, that is, the main grid line on at least one main surface of the solar cell is formed by printing a low-temperature paste, and the low-temperature paste can be formed into a main grid line by low-temperature curing, which can prevent the main grid line formed by the low-temperature paste from piercing a passivation layer, thereby preventing the main grid line on at least one main surface of the solar cell from contacting with a doping layer of the solar cell, thereby effectively reducing the opening voltage loss of the solar cell.

[0014] 2. Compared with high-temperature slurry, the low-temperature slurry contains different organic carriers, conductive metal particles, etc. In particular, the low-temperature slurry does not contain glass powder that can etch or damage the passivation layer. The low-temperature slurry combined with low-temperature curing can achieve good conductive function of the main grid line while avoiding the damage of the passivation layer of the solar cell by the curing of the low-temperature slurry, so that the passivation layer can better isolate the doping layer and the main grid line formed by the curing of the low-temperature slurry, thereby avoiding the main grid line formed by the low-temperature slurry from contacting the doping layer to form metal recombination, effectively reducing the opening voltage loss of the solar cell, and increasing the opening voltage of the solar cell, thereby further improving the photoelectric conversion efficiency of the passivated contact solar cell. BRIEF DESCRIPTION OF THE DRAWINGS

[0015] Figure 1 is a schematic diagram of the main process of a method for preparing a solar cell according to an embodiment of the present invention;

[0016] Figure 2 This is a schematic diagram of the main process of a first specific implementation method of forming a main grid line by curing a printed low-temperature slurry according to an embodiment of the present invention;

[0017] Figure 3 1 is a schematic diagram of the main process of a second specific implementation method of forming a main grid line by curing and printing a low-temperature slurry according to an embodiment of the present invention;

[0018] Figure 4 1 is a schematic diagram of the main process of a third specific implementation method of forming a main grid line by curing and printing a low-temperature slurry according to an embodiment of the present invention;

[0019] Figure 5 It is a schematic diagram of the main process of preparing a solar substrate including a doping layer and an emitter according to an embodiment of the present invention. DETAILED DESCRIPTION

[0020] In the prior art, the main grid lines and fine grid lines of TOPCon cells are generally formed by synchronous sintering (i.e., co-firing after the slurry for forming the main grid lines and the slurry for forming the fine grid lines are printed). This co-firing method, whether printing the main grid lines first and then the fine grid lines, or printing the fine grid lines first and then the main grid lines, will have the problem of the main grid lines burning through the passivation layer and the main grid lines contacting the doped layer. The contact between the main grid lines and the doped layer causes the metal composite of the solar cell to be still high, which has a greater negative impact on the electrical performance of the solar cell. This also means that the photoelectric conversion rate of TOPCon cells in the prior art still has a certain room for improvement.

[0021] In order to solve the above problems existing in existing solar cells (especially TOPCon cells), an embodiment of the present invention provides a method for preparing a solar cell and a solar cell prepared based on the method.

[0022] Figure 1 FIG. 2 is a schematic diagram showing the main process of a method for preparing a solar cell according to an embodiment of the present invention. Figure 1 As shown, the method for preparing the solar cell may include the following steps:

[0023] Step S101: forming main grid lines on at least one main surface of a solar cell by curing printed low-temperature paste, wherein, in addition to the main grid lines formed by curing the low-temperature paste, other grid lines of the solar cell are formed by high-temperature sintering and printing high-temperature paste, and the step of curing the printed low-temperature paste is after the step of forming other grid lines.

[0024] The curing of the printed low-temperature paste refers to printing the low-temperature paste on at least one main surface with sintered fine grid lines according to the distribution of the main grid lines, and then curing the low-temperature paste.

[0025] The low temperature paste refers to a paste containing conductive metals (such as silver, copper, etc.) that can be cured at low temperature (180°C to 240°C), which is completely different from the high temperature paste used to form fine grid lines. In a preferred embodiment, the low temperature paste does not contain glass powder.

[0026] In the method for preparing the solar cell provided in the above-mentioned embodiment, the main grid lines of at least one main surface of the solar cell are formed by curing the printed low-temperature paste, that is, the main grid lines of at least one main surface of the solar cell are formed by printing the low-temperature paste, and the low-temperature paste can be formed into the main grid lines by low-temperature curing, which can prevent the main grid lines formed by the low-temperature paste from piercing the passivation layer, thereby preventing the main grid lines of at least one main surface of the solar cell from contacting the doping layer of the solar cell, thereby effectively reducing the opening voltage loss of the solar cell.

[0027] In addition, compared with high-temperature paste, the low-temperature paste used to form the main grid line contains different organic carriers, conductive metal particles, etc., especially the low-temperature paste does not contain glass powder that can etch or damage the passivation layer, so that the low-temperature paste combined with low-temperature curing can achieve good conductive function of the main grid line while avoiding the low-temperature paste curing to damage the passivation layer of the solar cell, so that the passivation layer can better isolate the doping layer and the main grid line formed by the curing of the low-temperature paste, thereby avoiding the main grid line formed by the low-temperature paste from contacting the doping layer to form metal recombination, effectively reducing the opening voltage loss of the solar cell, and increasing the opening voltage of the solar cell, thereby further improving the photoelectric conversion efficiency of the passivated contact solar cell.

[0028] There are three specific implementation methods for the above step S101.

[0029] Specifically, Figure 2 As shown, a first specific implementation of step S101 may include the following steps:

[0030] Step S1011: synchronously printing fine grid line paste and main grid line paste on the front side of the prepared solar cell substrate including the doping layer or the emitter;

[0031] Step S1012: printing fine grid line paste on the back side of the prepared solar cell substrate including the doping layer or the emitter;

[0032] Step S1013: high temperature sintering to form electrode contacts;

[0033] Step S1014: printing low-temperature busbar slurry on the back side of the solar cell substrate including front fine grid lines, front main grid lines and back fine grid lines, and curing the low-temperature busbar slurry at low temperature.

[0034] It can be understood that after the above step S1011, the fine grid line paste and the main grid line paste printed synchronously in step S1011 can be preliminarily cured to facilitate the operation of the subsequent step S1012.

[0035] Among them, the function of step S1013 is mainly to form corresponding gate lines through high-temperature sintering of the fine gate paste and main gate paste printed in step S1011 and the fine gate paste printed in step S1012, and in the process of forming the gate lines, the fine gate lines formed by the fine gate paste pierce the passivation layer and contact the doping layer.

[0036] pass Figure 2 The process shown achieves low temperature slurry formation of the main grid lines on the back of the solar cell.

[0037] Specifically, Figure 3 As shown, the second specific implementation of the above step S101 may include the following steps:

[0038] Step S1011': printing fine grid line paste on the front side of the prepared solar substrate including the doping layer or the emitter;

[0039] Step S1012': synchronously printing fine grid line paste and main grid line paste on the back side of the prepared solar cell substrate including the doping layer or the emitter;

[0040] Step S1013': high temperature sintering to form electrode contacts;

[0041] Step S1014 ′: printing low-temperature busbar paste on the front side of the solar cell substrate including the front fine grid lines, the back fine grid lines and the back busbars, and curing the low-temperature busbar paste at low temperature.

[0042] It can be understood that after the above step S1011 ′, the fine grid line paste printed in step S1011 ′ may be preliminarily cured to facilitate the operation of the subsequent step S1012 ′.

[0043] The function of step S1013' is mainly to form corresponding gate lines by high-temperature sintering the fine gate paste printed in step S1011' and the fine gate paste and main gate paste printed in step S1012', and in the process of forming the gate lines, the fine gate lines formed by the fine gate paste pierce the passivation layer and contact the doping layer.

[0044] pass Figure 3 The process shown enables low temperature slurry to form the main grid lines on the front side of the solar cell.

[0045] Specifically, Figure 4 As shown, the third specific implementation of the above step S101 may include the following steps:

[0046] Step S1011": printing fine grid line paste on the front side of the prepared solar substrate including the doping layer or the emitter;

[0047] Step S1012”: printing fine grid line paste on the back side of the prepared solar cell substrate including the doping layer or the emitter;

[0048] Step S1013": high temperature sintering to form electrode contacts;

[0049] Step S1014": printing low-temperature busbar slurry on the front and back sides of the solar cell substrate including the front fine grid lines and the back fine grid lines, respectively, and curing the low-temperature busbar slurry at low temperature.

[0050] It can be understood that after the above step S1011 ″, the fine grid line paste printed in step S1011 ″ may be preliminarily cured to facilitate the operation of the subsequent step S1012 ″.

[0051] Among them, the function of step S1013" is mainly to form corresponding gate lines by high-temperature sintering of the fine gate paste printed in step S1011" and the fine gate paste printed in step S1012", and in the process of forming the gate lines, the fine gate lines formed by the fine gate paste pierce the passivation layer and contact the doping layer.

[0052] pass Figure 4 The process shown is to realize low-temperature slurry to form the main grid lines on the front and back of the solar cell respectively.

[0053] Furthermore, for the above Figures 2 to 4 Any of the embodiments shown, after the high-temperature sintering step and before printing the low-temperature main grid line paste, further includes: performing light injection or electric injection treatment on the solar substrate after high-temperature sintering. Because the temperature of the light injection / electric injection treatment is higher than the curing temperature of the low-temperature paste, the light injection / electric injection process step needs to be set between the process of forming fine grid lines and the process of forming main grid lines. By adding light injection and electric injection treatment after the high-temperature sintering step and before printing the low-temperature main grid line paste, it is prevented that the temperature of the light injection / electric injection process destroys the main grid lines formed by the low-temperature paste.

[0054] Specifically, the curing temperature of the printed low-temperature busbar paste is 180° C. to 240° C., and the curing time is 8 to 15 minutes. By controlling the curing temperature and curing time, the busbar formed by the low-temperature busbar paste can be completely cured, and the formed busbar has better conductive properties.

[0055] Specifically, the specific implementation of printing the low-temperature busbar paste and curing the low-temperature busbar paste at low temperature in the above embodiment may include: printing the low-temperature busbar paste multiple times in a stacked manner and performing low-temperature curing after each printing of the low-temperature busbar paste.

[0056] Among them, before the last printing of the low-temperature main grid line paste, the curing temperature of the low-temperature main grid line paste printed each time is 180°C ~ 240°C, and the curing time is 30s ~ 70s; by controlling the curing temperature and curing time of the low-temperature main grid line paste printed each time before the last printing of the low-temperature main grid line paste, curing in a short time reduces the fluidity of the low-temperature main grid paste, ensuring the stability of the main grid line while preventing the main grid line from being over-cured and causing partial structural rupture.

[0057] The curing temperature of the low-temperature main grid line paste printed for the last time is 180° C. to 240° C., and the curing time is 8 to 15 minutes.

[0058] By means of the above-mentioned multiple layered printing of low-temperature busbar paste, the line height of the busbar formed by the low-temperature busbar paste can be increased while the line width remains unchanged, thereby improving the aspect ratio of the busbar formed by the low-temperature busbar paste, reducing the line resistance of the busbar line and the series resistance of the solar cell, so as to effectively improve the fill factor of the solar cell and further improve the cell efficiency.

[0059] Furthermore, the method for preparing the solar cell further includes: a step of preparing a solar cell substrate including a doping layer and an emitter.

[0060] Specifically, Figure 5 As shown, the specific implementation of the step of preparing a solar substrate including a doping layer and an emitter may include the following steps:

[0061] Step S001: Diffusing a P-type doping element on the front side of an N-type silicon substrate to form a p+ emitter;

[0062] Step S002: sequentially preparing a tunneling oxide passivation layer and an N-type doped polysilicon layer on the back side of the N-type silicon substrate;

[0063] The tunneling oxide passivation layer is generally made of silicon oxide, and its thickness is 1 to 3 nm.

[0064] Wherein, the thickness of the N-type doped polysilicon layer is 50-150 nm.

[0065] Step S003: preparing a front passivation anti-reflection layer and a back passivation anti-reflection layer.

[0066] It can be understood that after the above-mentioned step S001 and before step S002, it can further include: removing the emitter and the silicon glass layer containing P-type doping elements stacked in sequence on the back and side of the N-type silicon substrate through hydrofluoric acid etching, and removing the silicon glass layer containing P-type doping elements on the front of the N-type silicon substrate; and placing the N-type silicon substrate in an alkaline solution to polish the back of the silicon wafer or prepare a small tower base structure.

[0067] The front passivation anti-reflection film / back passivation anti-reflection film may include at least one of aluminum oxide, silicon oxide, gallium oxide, silicon nitride, aluminum nitride, and silicon oxynitride.

[0068] Furthermore, an embodiment of the present invention provides a solar cell prepared by the preparation method provided in the above embodiment. The solar cell includes: a main grid line formed by curing and printing a low-temperature paste and other grid lines formed by high-temperature sintering and printing a high-temperature paste, wherein:

[0069] A main grid line formed by low temperature slurry is located on at least one main surface of the solar cell;

[0070] Other grid lines formed by high temperature paste are distributed on two main surfaces of the solar cell;

[0071] The main grid lines formed by the low temperature slurry are formed after the other grid lines are formed.

[0072] Specifically, the front main grid lines of the solar cell are formed by curing the low-temperature paste.

[0073] The back main grid of the solar cell is formed by curing the low-temperature paste.

[0074] The solar cell of this structure has a main grid line on at least one main surface formed by printing a low-temperature paste, and the low-temperature paste can be formed into a main grid line by low-temperature curing. This can prevent the main grid line formed by the low-temperature paste from piercing the passivation layer, thereby preventing the main grid line on at least one main surface of the solar cell from contacting the doping layer of the solar cell, thereby effectively reducing the opening voltage loss of the solar cell.

[0075] Optionally, the front main grid lines and / or the back main grid lines of the solar cell are formed by curing a low-temperature paste.

[0076] Optionally, both the front side fine grid lines and the back side fine grid lines of the solar cell are formed by high temperature sintering and printing of high temperature paste.

[0077] Several specific examples and comparative examples, as well as test data of solar cells prepared according to the specific examples and comparative examples, are described in detail below.

[0078] Embodiment 1:

[0079] Step A1: preparing a battery substrate: using an N-type silicon substrate as a silicon substrate, placing it in a texturing liquid for texturing treatment; diffusing boron elements, and performing a boron diffusion process on the front side of the N-type silicon substrate to form a battery p+ emitter; removing the emitter and borosilicate glass layers stacked in sequence on the front, back and side through hydrofluoric acid etching treatment; placing the N-type silicon substrate in an alkaline solution to perform a polishing treatment or a small tower base structure on the back side of the silicon wafer; sequentially preparing a tunneling oxide layer and an N-type doped polysilicon layer on the back side of the N-type silicon substrate, wherein the tunneling oxide layer is silicon oxide, and the thickness of the tunneling oxide layer is controlled to be 1 to 3 nm, and the thickness of the N-type doped polysilicon layer is 50 to 150 nm; using ALD, PECVD and other equipment to deposit a passivation film on the front and back sides of the battery substrate to obtain a front passivation anti-reflection layer and a back passivation anti-reflection layer, and the front passivation anti-reflection film / back passivation anti-reflection film includes at least one of aluminum oxide, silicon oxide, gallium oxide, silicon nitride, aluminum nitride, and silicon oxynitride.

[0080] Step B1: Printing front fine grid lines and back fine grid lines on the front and back of the battery substrate respectively; then performing high-temperature sintering to form electrode contacts, wherein the high-temperature sintering temperature is 700°C to 900°C.

[0081] Step C1: light injection or electrical injection treatment; wherein the treatment temperature during light injection or electrical injection is 350° C. to 500° C.

[0082] Step D1: Print low-temperature busbar slurry on the front and back of the battery substrate at one time, and cure at low temperature to form front busbars and back busbars to obtain a high-efficiency passivated contact solar cell, wherein the curing temperature is 180°C to 240°C and the curing time is 8min to 12min.

[0083] Embodiment 2:

[0084] Step A2 is the same as step A1 of Example 1 and will not be described again here.

[0085] Step B2: Printing front fine grid lines, back fine grid lines and back main grid lines on the front and back of the battery substrate respectively by high temperature slurry; then performing high temperature sintering to form electrode contacts; wherein the high temperature sintering temperature is 700℃~900℃.

[0086] Step C2: light injection or electrical injection treatment; wherein the treatment temperature during light injection or electrical injection is 350°C to 500°C.

[0087] Step D2: Printing low-temperature busbar slurry once on the front of the battery substrate, curing at low temperature, and forming a front busbar line on the front of the battery substrate; wherein the curing temperature is 180° C. to 240° C., and the curing time is 8 min to 12 min.

[0088] Embodiment 3:

[0089] Step A3 is the same as step A1 in Example 1 and will not be described again here.

[0090] Step B3: Printing front fine grid lines, back fine grid lines and back main grid lines on the front and back of the battery substrate respectively; and sintering at high temperature to form electrode contacts; wherein the high temperature sintering temperature is 700°C to 900°C.

[0091] Step C3: light injection or electrical injection treatment; wherein the treatment temperature during light injection or electrical injection is 350°C to 500°C.

[0092] Step D3: Printing low-temperature busbar paste on the front side of the battery substrate by secondary printing, and curing at low temperature to form a front busbar line on the front side of the battery substrate; wherein, printing the low-temperature busbar paste by secondary printing is specifically, printing the low-temperature busbar paste once and then performing the first curing, wherein the curing temperature of the first curing is 180℃~240℃, and the curing time is 30s~70s; then printing the low-temperature busbar paste for the second time in the same area, and then performing secondary curing, wherein the secondary curing temperature is 180℃~240℃, and the curing time is 8min~12min.

[0093] Embodiment 4:

[0094] Step A4 is the same as step A1 of Example 1 and will not be described again here.

[0095] Step B4: Printing front fine grid lines, back fine grid lines and front main grid lines on the front and back of the battery substrate respectively; then performing high-temperature sintering to form electrode contacts, wherein the high-temperature sintering temperature is 700°C to 900°C.

[0096] Step C4: light injection or electrical injection treatment; wherein the treatment temperature during light injection or electrical injection is 350°C to 500°C.

[0097] Step D4: Print low-temperature busbar slurry once on the back of the battery substrate, and cure at low temperature to form back busbar lines on the back of the battery substrate, wherein the curing temperature is 180° C. to 240° C. and the curing time is 8 min to 12 min.

[0098] Comparative Example:

[0099] Step A' is the same as step A1 of Example 1 and will not be described again.

[0100] Step B' uses high temperature slurry to print front fine grid lines, back fine grid lines, front main grid lines and back main grid lines on the front and back of the battery substrate respectively; then performs high temperature sintering to form electrode contacts, wherein the high temperature sintering temperature is 700℃~900℃.

[0101] Step C': light injection or electrical injection treatment; wherein the treatment temperature during light injection or electrical injection is 350°C to 500°C.

[0102] It is worth noting that solar cells under different combinations of condition parameter ranges can be prepared for the above-mentioned embodiments 1 to 4 and the comparative example. Further, by statistically analyzing the cell current (Isc), opening voltage (Voc), fill factor (FF (%)) and cell efficiency Eta (%) of various solar cells prepared in the above-mentioned embodiments 1 to 4 and the comparative example, the statistical results are shown in the following Table 1.

[0103] Table 1

[0104]

[0105] It can be seen from Table 1 above that the busbar lines formed by printing and curing low-temperature busbar slurry are beneficial to improving the opening voltage, fill factor and efficiency of solar cells.

[0106] In summary, the technical solutions provided by various embodiments of the present invention are as follows:

[0107] Technical solution 1, a method for preparing a solar cell, comprising:

[0108] Step A: forming a main grid line on at least one main surface of a solar cell by curing the printed low-temperature paste, wherein:

[0109] In addition to the main grid lines formed by curing the low-temperature paste, other grid lines of the solar cell are formed by high-temperature sintering of printed high-temperature paste, and the step of curing the printed low-temperature paste is after the step of forming other grid lines.

[0110] Technical solution 2: According to the method for preparing a solar cell according to technical solution 1, step A comprises:

[0111] Step A1: synchronously printing fine grid line paste and main grid line paste on the front side of the prepared solar cell substrate including the doping layer or the emitter;

[0112] Step A2: printing fine grid line paste on the back side of the prepared solar substrate including the doping layer or the emitter;

[0113] Step A3: high temperature sintering to form electrode contacts;

[0114] Step A4: printing low-temperature busbar slurry on the back of a solar cell substrate including front fine grid lines, front main grid lines and back fine grid lines, and curing the low-temperature busbar slurry at low temperature.

[0115] Technical solution 3: According to the method for preparing a solar cell according to technical solution 1, step A comprises:

[0116] Step A1': printing fine grid line paste on the front side of the prepared solar substrate including the doping layer or the emitter;

[0117] Step A2': synchronously printing fine grid line paste and main grid line paste on the back side of the prepared solar cell substrate including the doping layer or the emitter;

[0118] Step A3': high temperature sintering to form electrode contacts;

[0119] Step A4': printing low-temperature busbar paste on the front side of the solar cell substrate including front fine grid lines, back fine grid lines and back busbars, and curing the low-temperature busbar paste at low temperature.

[0120] Technical solution 4: According to the method for preparing a solar cell according to technical solution 1, step A comprises:

[0121] Step A1": printing fine grid line paste on the front side of the prepared solar substrate including the doping layer or the emitter;

[0122] Step A2”: printing fine grid line paste on the back side of the prepared solar substrate including the doping layer or the emitter;

[0123] Step A3": high temperature sintering to form electrode contacts;

[0124] Step A4": printing low-temperature busbar slurry on the front and back sides of a solar cell substrate including front fine grid lines and back fine grid lines, respectively, and curing the low-temperature busbar slurry at low temperature.

[0125] Technical solution 5: The method for preparing a solar cell according to any one of technical solutions 2 to 4, after the high-temperature sintering step and before printing the low-temperature busbar paste, further comprises:

[0126] The solar cell substrate after high temperature sintering is subjected to light injection or electricity injection treatment.

[0127] Technical solution 6: According to the method for preparing a solar cell according to any one of technical solutions 2 to 4, the printing of low-temperature busbar paste and low-temperature curing of the low-temperature busbar paste comprises:

[0128] The low-temperature busbar paste is printed multiple times in layers, and low-temperature curing is performed after each printing of the low-temperature busbar paste.

[0129] Technical solution 7: A method for preparing a solar cell according to any one of technical solutions 2 to 4,

[0130] The curing temperature of the printed low-temperature main grid line paste is 180° C. to 240° C., and the curing time is 8 to 15 minutes.

[0131] Technical solution 8: The method for preparing a solar cell according to technical solution 6,

[0132] Before the last printing of the low-temperature busbar paste, the curing temperature of each printed low-temperature busbar paste is 180° C. to 240° C., and the curing time is 30s to 70s;

[0133] The curing temperature of the low-temperature main grid line paste printed for the last time is 180° C. to 240° C., and the curing time is 8 to 15 minutes.

[0134] Technical solution 9. The method for preparing a solar cell according to any one of technical solutions 1 to 4 and 8, further comprising:

[0135] Step A0: a step of preparing a solar cell substrate including a doping layer and an emitter.

[0136] Technical solution 10. According to the method for preparing a solar cell according to technical solution 9, step A0 comprises:

[0137] Step A01: Diffusing a P-type doping element on the front side of an N-type silicon substrate to form a p+ emitter;

[0138] Step A02: sequentially preparing a tunneling oxide passivation layer and an N-type doped polysilicon layer on the back side of the N-type silicon substrate;

[0139] Step A03: preparing a front passivation anti-reflection layer and a back passivation anti-reflection layer.

[0140] Technical solution 11, a solar cell prepared by the preparation method according to any one of technical solutions 1 to 9, comprising: a main grid line formed by curing and printing a low-temperature paste and other grid lines formed by high-temperature sintering and printing a high-temperature paste, wherein:

[0141] The main grid line formed by the low-temperature slurry is located on at least one main surface of the solar cell;

[0142] Other grid lines formed by the high temperature paste are distributed on two main surfaces of the solar cell;

[0143] The main gate lines formed by the low-temperature slurry are formed after the other gate lines are formed.

[0144] Technical solution 12. The solar cell according to technical solution 11,

[0145] The front main grid line of the solar cell is formed by curing the low-temperature slurry;

[0146] and / or,

[0147] The back main grid line of the solar cell is formed by curing low-temperature slurry.

[0148] Technical solution 13. The solar cell according to technical solution 11 or 12,

[0149] The front fine grid lines and the back fine grid lines of the solar cell are both formed by high-temperature sintering and printing of high-temperature paste.

[0150] The introduction provided in the above steps is only used to help understand the method, structure and core idea of ​​the present invention. For ordinary technicians in this technical field, without departing from the principle of the present invention, several improvements and modifications can be made to the present invention, and these improvements and modifications also belong to the scope of protection of the claims of the present invention.

Claims

1. A method for preparing a solar cell, characterized in that: include: Step A: forming a main grid line on at least one main surface of a solar cell by curing the printed low-temperature paste, wherein: In addition to the main grid lines formed by curing the low-temperature paste, other grid lines of the solar cell are formed by high-temperature sintering of printed high-temperature paste, and the step of curing the printed low-temperature paste is after the step of forming other grid lines.

2. The method for preparing a solar cell according to claim 1, characterized in that: Step A includes: Step A1: synchronously printing fine grid line paste and main grid line paste on the front side of the prepared solar cell substrate including the doping layer or the emitter; Step A2: printing fine grid line paste on the back side of the prepared solar substrate including the doping layer or the emitter; Step A3: high temperature sintering to form electrode contacts; Step A4: printing low-temperature busbar slurry on the back of a solar cell substrate including front fine grid lines, front main grid lines and back fine grid lines, and curing the low-temperature busbar slurry at low temperature.

3. The method for preparing a solar cell according to claim 1, characterized in that: Step A includes: Step A1': printing fine grid line paste on the front side of the prepared solar substrate including the doping layer or the emitter; Step A2': synchronously printing fine grid line paste and main grid line paste on the back side of the prepared solar cell substrate including the doping layer or the emitter; Step A3': high temperature sintering to form electrode contacts; Step A4': printing low-temperature busbar paste on the front side of the solar cell substrate including front fine grid lines, back fine grid lines and back busbars, and curing the low-temperature busbar paste at low temperature.

4. The method for preparing a solar cell according to claim 1, characterized in that: Step A includes: Step A1": printing fine grid line paste on the front side of the prepared solar substrate including the doping layer or the emitter; Step A2”: printing fine grid line paste on the back side of the prepared solar substrate including the doping layer or the emitter; Step A3": high temperature sintering to form electrode contacts; Step A4": printing low-temperature busbar slurry on the front and back sides of a solar cell substrate including front fine grid lines and back fine grid lines, respectively, and curing the low-temperature busbar slurry at low temperature.

5. The method for preparing a solar cell according to any one of claims 2 to 4, characterized in that: After the high temperature sintering step and before printing the low temperature busbar paste, it also includes: The solar cell substrate after high temperature sintering is subjected to light injection or electricity injection treatment.

6. The method for preparing a solar cell according to any one of claims 2 to 4, characterized in that: The printing of low-temperature busbar slurry and low-temperature curing of the low-temperature busbar slurry comprises: The low-temperature busbar paste is printed multiple times in layers, and low-temperature curing is performed after each printing of the low-temperature busbar paste.

7. The method for preparing a solar cell according to any one of claims 2 to 4, characterized in that: The curing temperature of the printed low-temperature main grid line paste is 180° C. to 240° C., and the curing time is 8 to 15 minutes.

8. The method for preparing a solar cell according to claim 6, characterized in that: Before the last printing of the low-temperature busbar paste, the curing temperature of each printed low-temperature busbar paste is 180° C. to 240° C., and the curing time is 30s to 70s; The curing temperature of the low-temperature main grid line paste printed for the last time is 180° C. to 240° C., and the curing time is 8 to 15 minutes.

9. The method for preparing a solar cell according to any one of claims 1 to 4 and 8, characterized in that: Also includes: Step A0: a step of preparing a solar cell substrate including a doping layer and an emitter.

10. A solar cell prepared by the preparation method according to any one of claims 1 to 9, characterized in that: It includes: main grid lines formed by low-temperature slurry printed by curing and other grid lines formed by high-temperature slurry printed by high-temperature sintering, wherein: The main grid line formed by the low-temperature slurry is located on at least one main surface of the solar cell; Other grid lines formed by the high temperature paste are distributed on two main surfaces of the solar cell; The main gate lines formed by the low-temperature slurry are formed after the other gate lines are formed.

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