Preparation method of bottom cell of perovskite / crystalline silicon laminated solar cell, bottom cell and laminated solar cell thereof

Abstract

The invention discloses a preparation method of a bottom cell of a perovskite / crystalline silicon laminated solar cell, which comprises the following steps of: providing a bottom cell precursor with a surface heavily doped silicon layer and / or an emitter layer exposed, and depositing a hydrogen-rich metal oxide layer on the front surface or double surfaces of the bottom cell precursor by adopting an ALD (Atomic Layer Deposition) method; depositing a hydrogen injection passivation layer on the emitter layer on the back surface of the bottom cell precursor by adopting a PECVD method; printing low-aluminum-content silver paste on the hydrogen injection passivation layer to obtain a metal electrode grid line, and drying, shaping and slightly sintering the metal electrode grid line; and placing the lightly sintered bottom cell precursor in LECO equipment, and carrying out single-sided LECO treatment on a back metal electrode of the bottom cell to obtain the bottom cell. The preparation method is simple, streamline production is easy, the bottom cell precursor does not need to be additionally processed, the bottom cell precursor on a production line can be cut out for back metal electrode preparation and subsequent single-side LECO processing, and preparation and removal of a front metal electrode of the bottom cell are not needed.

Description

Technical Field

[0001] The present invention belongs to the technical field of solar cells, and in particular relates to a method for preparing a bottom cell of a perovskite / crystalline silicon tandem solar cell, the bottom cell and the tandem solar cell. Background Art

[0002] In the current process of manufacturing perovskite / crystalline silicon stacked cells, for TOPCon bottom cells, a metal electrode needs to be prepared on the back of the bottom cell to connect to the electrodes of the battery testing equipment. The metal electrode on the back of the bottom cell is essential to extract the excess carriers generated by the crystalline silicon substrate in the bottom cell and conduct them into the battery testing system or external circuit to form a closed circuit. Due to the temperature range of the perovskite top cell, the metal electrode on the back of the bottom cell needs to be completed before the hydrogen injection passivation layer on the front of the bottom cell is removed.

[0003] In the mass production of bottom cells, the back metal electrode is typically produced using the screen printing-sintering (SPF) method. A metal electrode paste is first printed onto the back hydrogen-implanted passivation layer to form a pattern. The metal is then sintered at temperatures exceeding 700°C to allow the metal to penetrate the back hydrogen-implanted passivation layer and reach the crystalline silicon substrate, where it reacts to form a metal / silicon compound, resulting in an ohmic contact electrode with low contact resistivity. This method consumes less metal than evaporation, offers flexible and adaptable electrode patterns, reduces single-wafer processing time, and allows for streamlined processing.

[0004] However, compared to silver, aluminum is rich in defects and has a high density of defect states at its deep energy levels. The aluminum content in the paste used in the conventional screen printing-sintering (SPF) method is relatively high, at 0.5-2%. Therefore, the metal electrode obtained by this method will form a defect-rich aluminum / silicon compound after the aluminum is combined with the crystalline silicon substrate, which will induce severe carrier recombination and a high carrier recombination rate, resulting in a very high metal recombination current density (J 0metal ), seriously affecting the overall passivation level of the bottom cell, thereby reducing the voltage and efficiency of the stacked cell. Furthermore, aluminum's electrical conductivity is not as high as silver, so aluminum-containing silver pastes require more silver and wider metal grid lines to achieve the target conductivity and series resistance, increasing metal consumption and production costs.

[0005] If this method is to be further used with the LECO (laser enhanced contact optimization) process, it is necessary to first prepare an additional metal electrode on the front of the bottom battery and then remove it after the LECO step. This makes the process complicated, causes great damage to the bottom battery, and requires additional consumption of raw materials, which increases costs. Summary of the Invention

[0006] In view of the problems existing in the preparation process of existing tandem solar cells and bottom cell back metal electrodes, the purpose of the present invention is to provide a method for preparing the bottom cell of a perovskite / crystalline silicon tandem solar cell, the bottom cell and the tandem solar cell.

[0007] The technical effects of the present invention are achieved through the following technical solutions.

[0008] In a first aspect, the present invention provides a method for preparing a bottom cell of a perovskite / crystalline silicon tandem solar cell, comprising the following steps:

[0009] 1) providing a bottom cell precursor with a heavily doped silicon layer and / or an emitter layer exposed on the surface, and depositing a hydrogen-rich metal oxide layer on the front side or both sides of the bottom cell precursor by atomic layer deposition (ALD);

[0010] 2) depositing a hydrogen implantation passivation layer on the emitter layer on the back side of the bottom cell precursor by plasma enhanced chemical vapor deposition (PECVD);

[0011] 3) Printing pure silver paste or low-aluminum silver paste on the hydrogen-implanted passivation layer on the back of the bottom cell precursor to obtain metal electrode grid lines, followed by drying, shaping, and light sintering to obtain lightly burned-through metal electrodes;

[0012] 4) The lightly sintered bottom cell precursor is placed in a laser enhanced contact optimization (LECO) device. The hydrogen-rich metal oxide layer on the front of the bottom cell precursor contacts the metal stage electrode of the LECO device, and the metal electrode grid line on the back of the bottom cell precursor contacts the probe electrode of the LECO device. The metal electrode on the back of the cell is subjected to single-sided LECO treatment to obtain a bottom cell.

[0013] Furthermore, in step 1), the conditions for the ALD method are: the deposition temperature is 50~400 The metal source pulse is 0.1~10s, the oxygen source pulse is 0.1~30s, the number of cycles is 1~500 times, and the oxygen source is deionized water or ozone.

[0014] Furthermore, in step 1), the material of the deposited metal oxide is selected from one or more of aluminum oxide, tin oxide, nickel oxide, zinc oxide, and the like.

[0015] Furthermore, in step 1), the thickness of the hydrogen-rich metal oxide layer is 20-50 nm.

[0016] Furthermore, in step 2), the hydrogen implantation passivation layer is a single-layer or multi-layer dielectric layer, and the hydrogen implantation passivation layer is selected from one or more of silicon nitride, silicon oxynitride, and silicon oxide.

[0017] Furthermore, in step 3), the percentage of aluminum in the low aluminum content silver paste to the total mass of the paste is 0-0.2%, preferably a pure silver paste that does not contain aluminum.

[0018] The present invention uses a low-aluminum silver paste to increase the contact resistivity of the metal / emitter contact. This means that thinner grid lines and less silver consumption can be used to achieve the same contact resistivity and battery series resistance, thereby reducing production costs. The use of pure silver paste without aluminum can reduce the metal composite current density of the metal / emitter contact, improve the overall passivation level of the bottom cell, and thus improve the open circuit voltage and efficiency of the stacked battery.

[0019] Furthermore, in step 3), the conditions for printing, drying, and sintering are: printing speed of 80-120 mm / s, ink return speed of 800-1200 mm / s, printing pressure of 80-120 N, and printing height offset of 3-7 mm; drying temperature of 220-280°C, and drying time of 8-12s; sintering peak temperature of 730-760°C, and sintering time of 25-35s; annealing peak temperature of 380-420°C, and annealing time of 20-40s.

[0020] Furthermore, in step 4), the LECO conditions are: negative bias intensity of 10-70%, laser intensity of 20-70%, laser scanning rate of 10,000-100,000 mm / s, and LECO probe electrode pressure of 60-140N.

[0021] In a second aspect, the present invention provides a bottom cell of a perovskite / crystalline silicon tandem solar cell, which is prepared using the above-mentioned method for preparing a bottom cell of a perovskite / crystalline silicon tandem solar cell.

[0022] In a third aspect, the present invention provides a perovskite / crystalline silicon tandem solar cell, wherein the tandem solar cell comprises a perovskite top cell and a crystalline silicon bottom cell, wherein the crystalline silicon bottom cell is the bottom cell as described above.

[0023] Compared with the prior art, the present invention has the following beneficial effects:

[0024] 1) Conductivity, protection, and hydrogen injection: Utilizing the high conductivity of the heavily doped silicon layer and the nanometer-thick metal oxide layer on its surface, single-sided LECO processing is performed after printing the metal electrode grid lines on the back of the bottom cell. The heavily doped silicon layer on the front side does not contact the metal stage electrode of the LECO device through the metal electrode; the hydrogen-rich metal oxide layer can protect the heavily doped silicon layer on the front side from contamination and damage while performing hydrogen injection passivation while allowing the circuit to be conductive.

[0025] 2) The present invention uses silver paste with low aluminum content, which can use thinner grid lines and less silver consumption to achieve the same contact resistivity and battery series resistance, thereby reducing production costs.

[0026] 3) After metallization processing, the bottom cell precursor of the present invention can reduce the density of defects in the metal / silicon compound, reduce the carrier recombination rate under the metal electrode grid line, avoid the decrease in the bottom cell passivation level caused by the back metal electrode and front contamination, increase the voltage contribution of the TOPCon bottom cell to the stacked cell, and improve the voltage and efficiency of the perovskite / TOPCon stacked solar cell.

[0027] 4) The preparation process of the present invention is simple and can be easily integrated into an assembly line. No additional processing is required for the bottom cell precursor. The bottom cell precursor on the production line can be intercepted for the preparation of the back metal electrode and subsequent single-sided LECO processing, without the need for the preparation and removal of the bottom cell front metal electrode. BRIEF DESCRIPTION OF THE DRAWINGS

[0028] Figure 1 Schematic diagram of the structure of the TOPCon bottom cell precursor in an embodiment of the present invention;

[0029] Figure 2 Schematic diagram of the structure of a TOPCon bottom cell precursor with a hydrogen-rich metal oxide layer deposited on the front side in an embodiment of the present invention;

[0030] Figure 3 Schematic diagram of the structure of a TOPCon bottom cell precursor with a back-side hydrogen injection passivation layer deposited in an embodiment of the present invention;

[0031] Figure 4 Schematic diagram of the structure of the TOPCon bottom cell precursor after the back metal electrode is printed and lightly sintered in an embodiment of the present invention;

[0032] Figure 5 Schematic diagram of the structure of the single-sided LECO processing process in an embodiment of the present invention;

[0033] Figure 6 It is a schematic structural diagram of the tandem solar cell of the present invention. DETAILED DESCRIPTION

[0034] In order to make the technical problems, technical solutions and beneficial effects solved by the present invention clearer, the present invention is further described in detail below in conjunction with specific embodiments. It should be understood that the embodiments described herein are part of the embodiments of the present invention, rather than all of the embodiments, and are only used to explain the present invention and are not intended to limit the present invention. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making creative work are within the scope of protection of the present invention.

[0035] In a first aspect, the present invention provides a method for preparing a bottom cell of a perovskite / crystalline silicon tandem solar cell, comprising the following steps:

[0036] 1) providing a bottom cell precursor with a heavily doped silicon layer and / or an emitter layer exposed on the surface, and depositing a hydrogen-rich metal oxide layer on the front side or both sides of the bottom cell precursor using an ALD method;

[0037] 2) depositing a hydrogen implantation passivation layer on the emitter layer on the back side of the bottom cell precursor using a PECVD method;

[0038] 3) Printing pure silver paste or low-aluminum silver paste on the hydrogen-implanted passivation layer on the back of the bottom cell precursor to obtain metal electrode grid lines, followed by drying, shaping, and light sintering to obtain lightly burned-through metal electrodes;

[0039] 4) Place the lightly sintered bottom cell precursor in a LECO device, so that the hydrogen-rich metal oxide layer on the front of the bottom cell precursor contacts the metal stage electrode of the LECO device, and the metal electrode grid line on the back of the bottom cell precursor contacts the probe electrode of the LECO device. Perform single-sided LECO treatment on the metal electrode on the back of the bottom cell to obtain the bottom cell.

[0040] In some specific embodiments, in step 1), the conditions for the ALD method are: the deposition temperature is 50~400 The metal source pulse is 0.1~10s, the oxygen source pulse is 0.1~30s, the number of cycles is 1~500 times, and the oxygen source is deionized water or ozone.

[0041] More specifically, the deposition temperature is 50 , 100 , 160 , 200 , 250 , 300 , 350 or 400 etc., preferably 150~300 ; The metal source pulse is 0.1s, 1s, 2s, 4s, 7s or 10s, etc., preferably 2~6s; the oxygen source pulse is 0.1s, 1s, 5s, 10s, 15s, 20s, 25s or 30s, etc., preferably 10~20s; the number of cycles is 1 time, 5 times, 10 times, 50 times, 100 times, 180 times, 230 times, 300 times, 340 times, 420 times or 500 times, etc., preferably 50~200 times.

[0042] In some specific embodiments, in step 1), the material of the deposited metal oxide is selected from one or more of aluminum oxide, tin oxide, nickel oxide, zinc oxide, and the like.

[0043] In some specific embodiments, in step 1), the thickness of the hydrogen-rich metal oxide layer is 20-50 nm. More specifically, the thickness of the hydrogen-rich metal oxide layer is 20 nm, 25 nm, 30 nm, 35 nm, 40 nm, 45 nm, or 50 nm.

[0044] In some specific embodiments, in step 2), the hydrogen implantation passivation layer is a single-layer or multi-layer dielectric layer, and the hydrogen implantation passivation layer is selected from one or more of silicon nitride, silicon oxynitride, and silicon oxide.

[0045] In some specific embodiments, in step 3), the aluminum content of the low aluminum content silver paste is 0-0.2% by weight of the total paste. More specifically, the aluminum content is 0, 0.01%, 0.05%, 0.1%, 0.15%, or 0.2%. A pure silver paste containing no aluminum is preferred.

[0046] The present invention uses a low-aluminum silver paste to increase the contact resistivity of the metal / emitter contact. This means that thinner grid lines and less silver consumption can be used to achieve the same contact resistivity and battery series resistance, thereby reducing production costs. The use of pure silver paste without aluminum can reduce the metal composite current density of the metal / emitter contact, improve the overall passivation level of the bottom cell, and thus improve the open circuit voltage and efficiency of the stacked battery.

[0047] In some specific embodiments, in step 3), the conditions for printing, drying, and sintering are: printing speed 80~120 mm / s, ink return speed 800~1200 mm / s, printing pressure 80~120 N, printing height offset 3~7 mm; drying temperature 220~280°C, drying time 8~12s; sintering peak temperature 730~760°C, sintering time 25~35s, annealing peak temperature 380~420°C, annealing time 20~40s.

[0048] More specifically, the printing speed is 80mm / s, 90mm / s, 100mm / s, 110mm / s or 120mm / s, etc.; the ink return speed is 800mm / s, 900mm / s, 1000mm / s, 1100mm / s or 1200mm / s. mm / s, etc.; the printing pressure is 80N, 90N, 100N, 110N or 120N, etc.; the printing height offset is 3mm, 4mm, 5mm, 6mm or 7mm, etc.; the drying temperature is 220℃, 230℃, 240℃, 250℃, 260℃, 270℃ or 280℃, etc.; the drying time is 8s, 9s, 10s, 11s or 12s, etc.; the sintering peak temperature is 730℃, 740℃, 750℃ or 760℃, etc.; the sintering time is 25s, 28s, 30s, 32s or 35s, etc.; the annealing peak temperature is 380℃, 390℃, 400℃, 410℃ or 420℃, etc., and the annealing time is 20s, 25s, 28s, 30s, 35s or 40s.

[0049] In some specific embodiments, in step 4), the LECO conditions are: negative bias intensity of 10-70%, laser intensity of 20-70%, laser scanning rate of 10,000-100,000 mm / s, and LECO probe electrode pressure of 60-140N.

[0050] More specifically, the negative bias intensity is 10%, 20%, 30%, 40%, 50%, 60% or 70%; the laser intensity is 20%, 30%, 35%, 42%, 50%, 60% or 70%; the laser scanning rate is 10000mm / s, 20000mm / s, 30000mm / s, 40000mm / s, 50000mm / s, 60000mm / s, 80000mm / s or 100000mm / s; the LECO probe electrode pressure is 80N, 90N, 100N, 110N or 120N.

[0051] In a second aspect, the present invention provides a bottom cell of a perovskite / crystalline silicon tandem solar cell, which is prepared using the above-mentioned method for preparing a bottom cell of a perovskite / crystalline silicon tandem solar cell.

[0052] In a third aspect, the present invention provides a perovskite / crystalline silicon tandem solar cell, wherein the tandem solar cell comprises a perovskite top cell and a crystalline silicon bottom cell, wherein the crystalline silicon bottom cell is the bottom cell as described above.

[0053] The specific embodiments of the present invention will be further explained below through examples and comparative examples.

[0054] Unless otherwise specified, the materials and instruments used in the following description are conventional materials and conventional instruments, which can be obtained commercially. The methods in the examples are conventional methods in the art unless otherwise specified.

[0055] The bottom cell described in the present invention includes but is not limited to crystalline silicon solar cells with an n-type (or p-type) silicon substrate, an n-type (or p-type) TOPCon structure on one side, a TOPCon structure on both sides, a double-sided flat cell, a velvet-surfaced cell on one side and a flat cell on the other side, or a velvet-surfaced cell on both sides.

[0056] The bottom cell precursor in the embodiment of the present invention is a precursor with a heavily doped silicon layer and / or an emitter layer exposed on the surface, which is a typical TOPCon cell precursor. The schematic diagram of its structure is shown in FIG. Figure 1 As shown in the figure, the side containing the TOPCon structure is the front side, and the other side is the back side; from top to bottom, it consists of the first heavily doped silicon layer (n or p type), the tunneling silicon oxide layer, the single crystal silicon substrate (n or p type), and the emitter layer (p or n type).

[0057] Example 1

[0058] Preparation method of bottom cell of perovskite / crystalline silicon tandem solar cell , including the following steps:

[0059] 1) Preparation of hydrogen-rich metal oxide layer: Provide Figure 1 The bottom cell precursor shown is cleaned and dried, and then sent to the atomic layer deposition (ALD) system to deposit hydrogen-rich metal oxide on the front side of the bottom cell precursor. The material of the deposited metal oxide is aluminum oxide, and the thickness of the deposited hydrogen-rich metal oxide layer is 10nm; the deposition temperature is 300°C, the metal source pulse is 3s, the oxygen source pulse is 10s, the number of cycles is 60 times, the metal source is trimethylaluminum, and the oxygen source is deionized water; the metal oxide layer generated after the reaction of the oxygen source and the metal source is rich in hydrogen. The hydrogen-rich metal oxide layer can protect the first heavily doped silicon layer on the front side from contamination and damage while performing hydrogen injection passivation while allowing the circuit to be turned on, so the hydrogen-rich metal oxide layer is also the first hydrogen injection passivation layer. The structure of the bottom cell precursor after the hydrogen-rich metal oxide layer (first hydrogen injection passivation layer) is deposited on the front side is as shown Figure 2 shown.

[0060] 2) Preparation of back hydrogen injection passivation layer: The bottom cell precursor obtained in step 1) is fed into a plasma enhanced chemical vapor deposition (PECVD) system to deposit a dielectric hydrogen injection passivation layer on the emitter layer on the back of the bottom cell precursor. Figure 3 The second hydrogen-implanted passivation layer is silicon nitride, which contains a certain amount of hydrogen and has a protective effect on the back surface of the precursor.

[0061] 3) Preparation of the back metal electrode: Place the back of the bottom cell precursor obtained in step 2) upward, and use the screen printing method to print pure silver paste on the second hydrogen injection passivation layer on the back of the bottom cell to obtain a suspended metal electrode grid line, which is then dried, shaped, and lightly sintered to obtain a lightly burned-through metal electrode. At this time, the bonding between the metal electrode and the crystalline silicon substrate is still insufficient, and a metal-silicon compound of sufficient area and depth has not yet been generated, and an efficient ohmic contact has not yet been formed. The structure of the bottom cell precursor after the back metal electrode is printed and lightly sintered is as follows Figure 4 The printing, drying, and sintering conditions were as follows: printing speed 100 mm / s, ink return speed 1000 mm / s, printing pressure 100 N, printing height offset 5 mm; drying temperature 250°C, drying time 10 seconds; sintering peak temperature 750°C, sintering time 30 seconds, annealing peak temperature 400°C, annealing time 30 seconds.

[0062] 4) Single-sided LECO treatment: Place the lightly sintered bottom cell precursor in the LECO equipment, and perform single-sided LECO treatment on the metal electrode on the back of the bottom cell. After the treatment is completed, remove it from the LECO equipment to obtain a complete TOPCon bottom cell. The structure of the bottom cell during the single-sided LECO treatment and the connection of the LECO equipment electrodes are shown in the figure. Figure 5 As shown, the hydrogen-rich metal oxide layer on the front of the bottom cell precursor contacts the metal stage electrode of the LECO device, and the metal electrode grid line on the back of the bottom cell precursor contacts the probe electrode of the LECO device, forming a closed circuit. Among them, only the back of the bottom cell contains a metal electrode, and there is no metal electrode on the front. During the LECO process, only the back of the bottom cell undergoes LECO-related reactions. Therefore, this application refers to this technology as single-sided LECO technology. After LECO treatment, the metal electrode on the back of the bottom cell penetrates deeper into the second hydrogen injection passivation layer on the back, and is better bonded to the crystalline silicon substrate, forming an excellent ohmic contact. The LECO conditions are: negative bias intensity of 10%, laser intensity of 20%, laser scanning rate of 100,000 mm / s, and LECO probe electrode pressure of 100N.

[0063] Preparation of perovskite / crystalline silicon tandem solar cells: The TOPCon bottom cell obtained in step 4) is processed using common methods in the field of perovskite / crystalline silicon tandem solar cells. This mainly includes removing the first hydrogen injection passivation layer (hydrogen-rich metal oxide layer) on the front side, preparing the interface conductive layer, and making the perovskite top cell. A complete tandem solar cell is obtained, and its structure is as follows: Figure 6 shown.

[0064] Example 2

[0065] This embodiment includes most of the operating steps in Example 1 to prepare the bottom cell of the perovskite / crystalline silicon tandem solar cell and the perovskite / crystalline silicon tandem solar cell. The difference lies in that the materials and setting parameters used in step 1) to prepare the hydrogen-rich metal oxide layer are different: the deposited metal oxide material is tin oxide, and the thickness of the deposited hydrogen-rich metal oxide layer is 20 nm; the deposition temperature is 200°C, the metal source pulse is 3 s, the oxygen source pulse is 12 s, the number of cycles is 80, the metal source is tetrakis(dimethylamino)tin, and the oxygen source is deionized water.

[0066] Example 3

[0067] This embodiment includes most of the operating steps in Example 1 to prepare the bottom cell of the perovskite / crystalline silicon tandem solar cell and the perovskite / crystalline silicon tandem solar cell. The difference lies in that the materials and setting parameters used in step 1) to prepare the hydrogen-rich metal oxide layer are different: the material of the deposited metal oxide is nickel oxide, and the thickness of the deposited hydrogen-rich metal oxide layer is 20 nm; the deposition temperature is 230°C, the metal source pulse is 2s, the oxygen source pulse is 10s, and the number of cycles is 120 times; the metal source is nickelocene, and the oxygen source is ozone.

[0068] Example 4

[0069] This embodiment includes most of the operating steps in Example 1 to prepare the bottom cell of the perovskite / crystalline silicon tandem solar cell and the perovskite / crystalline silicon tandem solar cell. The difference lies in that the materials and setting parameters used in step 1) to prepare the hydrogen-rich metal oxide layer are different: the deposited metal oxide material is zinc oxide, and the thickness of the deposited hydrogen-rich metal oxide layer is 22 nm; the deposition temperature is 100°C, the metal source pulse is 1 s, the oxygen source pulse is 5 s, and the number of cycles is 110; the metal source is diethyl zinc, and the oxygen source is deionized water.

[0070] Example 5

[0071] This example includes most of the steps in Example 1 to prepare the bottom cell and perovskite / crystalline silicon tandem solar cell. The differences are that the materials used in step 2) for the backside hydrogen implantation passivation layer are silicon oxynitride and silicon oxide; and that the printing, drying, and sintering parameters in step 3) are different: the printing speed is 80 mm / s, the ink return speed is 800 mm / s, the printing pressure is 80 N, and the printing height offset is 3 mm; the drying temperature is 220°C, and the drying time is 12 seconds; the sintering peak temperature is 730°C, the sintering time is 35 seconds, and the annealing peak temperature is 380°C, with an annealing time of 40 seconds.

[0072] Example 6

[0073] This embodiment includes most of the operating steps in Example 1 to prepare the bottom cell of the perovskite / crystalline silicon tandem solar cell and the perovskite / crystalline silicon tandem solar cell, except that: in step 2), the materials used to prepare the back hydrogen injection passivation layer are silicon nitride, silicon oxynitride and silicon oxide; in step 3), the printing, drying and sintering setting parameters are different, with a printing speed of 120 mm / s, an ink return speed of 1200 mm / s, a printing pressure of 120 N, and a printing height offset of 7 mm; a drying temperature of 280°C and a drying time of 8 seconds; a sintering peak temperature of 760°C and a sintering time of 25 seconds, an annealing peak temperature of 420°C, and an annealing time of 20 seconds.

[0074] Example 7

[0075] This embodiment includes most of the operating steps in Example 1 to prepare the bottom cell of the perovskite / crystalline silicon tandem solar cell and the perovskite / crystalline silicon tandem solar cell, except that: Step 3) the slurry used for printing the back metal electrode: in the low aluminum content silver paste, the percentage of aluminum in the total mass of the paste is 0.05%.

[0076] Example 8

[0077] This embodiment includes most of the operating steps in Example 1 to prepare the bottom cell of the perovskite / crystalline silicon tandem solar cell and the perovskite / crystalline silicon tandem solar cell. The difference lies in the different slurry used for printing the back metal electrode in step 3) and the different printing, drying, and sintering setting parameters: in the low aluminum content silver paste, the percentage of aluminum in the total mass of the paste is 0.2%.

[0078] Example 9

[0079] This embodiment includes most of the operating steps in Example 1 to prepare the bottom cell of the perovskite / crystalline silicon tandem solar cell and the perovskite / crystalline silicon tandem solar cell. The difference is that the LECO conditions in step 4) are different: the negative bias intensity is 40%, the laser intensity is 55%, the laser scanning rate is 40000mm / s, and the LECO probe electrode pressure is 60N.

[0080] Example 10

[0081] This embodiment includes most of the operating steps in Example 1 to prepare the bottom cell of the perovskite / crystalline silicon tandem solar cell and the perovskite / crystalline silicon tandem solar cell. The difference is that the LECO conditions in step 4) are different: the bias intensity is 60%, the laser intensity is 25%, the laser scanning rate is 25000mm / s, and the LECO probe electrode pressure is 140N.

[0082] Comparative Example 1

[0083] The bottom cell of the perovskite / crystalline silicon tandem solar cell and the perovskite / crystalline silicon tandem solar cell were prepared according to the method of Example 1. The difference between this comparative example and Example 1 is that the bottom cell was prepared by the existing conventional method, the double-sided LECO process: pure silver paste was printed on the hydrogen injection passivation layer on the front and back of the bottom cell, and sintered at a high temperature of 800°C to form double-sided metal electrodes. After that, the back side was LECO processed, and the hydrogen injection passivation layer and metal electrode on the front side were removed on one side to prepare the bottom cell.

[0084] Comparative Example 2

[0085] The difference between this comparative example and Example 1 is that there is no step 1), that is, no hydrogen-rich metal oxide layer is deposited on the front or both sides of the bottom cell precursor: in step 4), the heavily doped silicon layer on the front side of the bottom cell precursor is in contact with the metal stage electrode of the LECO device.

[0086] Comparative Example 3

[0087] The difference between this comparative example and Example 1 is that there is no step 4), that is, only sintering without LECO: in step 3), a silver-aluminum paste with an aluminum content of 1.5% is printed on the emitter layer on the back of the bottom cell precursor, and sintered at a high temperature of 800°C to form a metal electrode, thereby obtaining a bottom cell.

[0088] Performance testing:

[0089] Performance tests were conducted on the bottom cell of the perovskite / crystalline silicon tandem solar cell and its tandem solar cell, using the above examples and comparative examples. The tests included the metal composite current density J0metal and contact resistivity of the metal / emitter contact, the photoluminescence (PL) intensity of the bottom cell, and the open-circuit voltage, fill factor, and efficiency of the tandem solar cell. The test results are shown in Table 1.

[0090] Table 1:

[0091]

[0092] The test results of Examples 1 to 8 show that the present invention uses a low aluminum content silver paste to increase the contact resistivity of the metal / emitter contact, that is, it is possible to use thinner gate lines and less silver consumption to achieve the same contact resistivity and battery series resistance, thereby reducing production costs.

[0093] The test results of Example 1 and Examples 7 and 8 show that the use of pure silver paste that does not contain aluminum can reduce the metal composite current density of the metal / emitter contact and improve the overall passivation level of the bottom cell, thereby improving the open circuit voltage and efficiency of the stacked cell.

[0094] The test results of Example 1 and Comparative Example 1 show that if the conventional method of "double-sided metal electrodes + back-side LECO + single-sided removal of the front metal electrode and front dielectric layer" is adopted, the metal composite current density increases, the contact resistivity and the PL value of the bottom cell decrease significantly, resulting in a decrease in the passivation level of the bottom cell, and thus a decrease in the open-circuit voltage of the stacked solar cell; moreover, the conventional method of preparing the bottom cell is complicated, causes great damage to the bottom cell, and requires additional consumption of raw materials, which increases the cost.

[0095] The test results of Example 1 and Comparative Example 2 show that step 1) is essential. If the heavily doped silicon layer on the front side directly contacts the metal stage electrode of the LECO device, the hydrogen injection passivation layer on the front side of the bottom cell will be lost. At the same time, the front side of the bottom cell will be contaminated by the metal stage electrode, resulting in an increase in the metal composite current density, a significant decrease in the contact resistivity and the PL value of the bottom cell, and a decrease in the passivation of the bottom cell, thereby significantly reducing the open circuit voltage and efficiency of the stacked solar cell.

[0096] The test results of Example 1 and Comparative Example 3 show that step 4) is essential. Moreover, if silver-aluminum paste with a high aluminum content is used to print the metal electrode, severe metal contact carrier recombination will occur after sintering, resulting in a significant increase in the metal composite current density, a significant decrease in the contact resistivity and the bottom cell PL value, resulting in a significant decrease in the bottom cell passivation, and further a significant decrease in the voltage and efficiency of the stacked solar cell.

[0097] The present invention is further described above with the aid of specific embodiments. However, it should be understood that the specific description herein should not be construed as limiting the essence and scope of the present invention. Various modifications made to the above embodiments by ordinary technicians in this field after reading this specification are all within the scope of protection of the present invention.

Claims

1. A method for preparing a bottom cell of a perovskite / crystalline silicon tandem solar cell, characterized in that: The steps include: 1) Providing the bottom cell precursor, wherein the bottom cell precursor is a precursor with a heavily doped silicon layer and / or an emitter layer exposed on the surface, and depositing a hydrogen-rich metal oxide layer on the front side or both sides of the bottom cell precursor using an ALD method; 2) depositing a hydrogen implantation passivation layer on the emitter layer on the back side of the bottom cell precursor using a PECVD method; 3) Printing a low-aluminum silver paste on the hydrogen-implanted passivation layer on the back of the bottom cell precursor to obtain a metal electrode grid line, which is then dried, shaped, and lightly sintered to obtain a lightly burned-through metal electrode; 4) Place the lightly sintered bottom cell precursor in a LECO device, so that the hydrogen-rich metal oxide layer on the front of the bottom cell precursor contacts the metal stage electrode of the LECO device, and the metal electrode grid line on the back of the bottom cell precursor contacts the probe electrode of the LECO device. Perform single-sided LECO treatment on the metal electrode on the back of the bottom cell to obtain the bottom cell.

2. The method for preparing the bottom cell of the perovskite / crystalline silicon tandem solar cell according to claim 1, characterized in that: In step 1), the conditions for the ALD method are: deposition temperature is 50~400 The metal source pulse is 0.1~10s, the oxygen source pulse is 0.1~30s, the number of cycles is 1~500 times, and the oxygen source is deionized water or ozone.

3. The method for preparing the bottom cell of the perovskite / crystalline silicon tandem solar cell according to claim 1, characterized in that: In step 1), the material of the deposited metal oxide is selected from one or more of aluminum oxide, tin oxide, nickel oxide, zinc oxide, and the like.

4. The method for preparing the bottom cell of the perovskite / crystalline silicon tandem solar cell according to claim 1, characterized in that: In step 1), the thickness of the hydrogen-rich metal oxide layer is 0.1-50 nm.

5. The method for preparing the bottom cell of the perovskite / crystalline silicon tandem solar cell according to claim 1, characterized in that: In step 2), the hydrogen implantation passivation layer is a single-layer or multi-layer dielectric layer, and the hydrogen implantation passivation layer is selected from one or more of silicon nitride, silicon oxynitride, and silicon oxide.

6. The method for preparing the bottom cell of the perovskite / crystalline silicon tandem solar cell according to claim 1, characterized in that: In step 3), in the low aluminum content silver paste, the percentage of aluminum in the total mass of the paste is 0-0.2%.

7. The method for preparing the bottom cell of the perovskite / crystalline silicon tandem solar cell according to claim 1, characterized in that: In step 3), the printing, drying, and sintering conditions are as follows: printing speed of 80-120 mm / s, ink return speed of 800-1200 mm / s, printing pressure of 80-120 N, and printing height offset of 3-7 mm; drying temperature of 220-280°C, and drying time of 8-12 seconds; sintering peak temperature of 730-760°C, and sintering time of 25-35 seconds; annealing peak temperature of 380-420°C, and annealing time of 20-40 seconds.

8. The method for preparing the bottom cell of the perovskite / crystalline silicon tandem solar cell according to claim 1, characterized in that: In step 4), the LECO conditions are: negative bias intensity of 10-70%, laser intensity of 20-70%, laser scanning rate of 10,000-100,000 mm / s, and LECO probe electrode pressure of 60-140 N.

9. A bottom cell of a perovskite / crystalline silicon tandem solar cell, characterized in that: The bottom cell is prepared by the method for preparing the bottom cell of the perovskite / crystalline silicon tandem solar cell according to any one of claims 1 to 8.

10. A perovskite / crystalline silicon tandem solar cell, comprising a perovskite top cell and a crystalline silicon bottom cell, characterized in that: The crystalline silicon bottom cell is the bottom cell according to claim 9.

Images