Passivation layer structure for solar cell, and preparation method therefor and use thereof

Abstract

Provided in the present invention are a passivation layer structure for a solar cell, and a preparation method therefor and the use thereof. The preparation method comprises: (1) subjecting the surface of a substrate to a dangling bond chemical activity modification treatment by means of one or more of nitrous oxide, ammonia gas and hydrogen, depositing an aluminum oxide film layer on the surface of the substrate, and subjecting the aluminum oxide film layer to a plasma treatment, so as to obtain a modified aluminum oxide film layer; (2) depositing an aluminum oxynitride film layer on the surface of the modified aluminum oxide film layer, so as to form a double-layer tandem structure; and (3) subjecting the double-layer tandem structure to an annealing treatment in a protective atmosphere. In the present invention, by subjecting the aluminum oxide film layer to the plasma treatment, aluminum oxide adsorbs more OH bonds and H bonds that have higher binding energy; and the aluminum oxynitride film layer deposited on the surface of the modified aluminum oxide film layer has the function of enhancing the passivation performance of the modified aluminum oxide film layer and the light absorption function of a solar cell, thereby improving the passivation effect.

Description

Solar cell passivation layer structure and preparation method and application thereof TECHNICAL FIELD

[0001] The present application relates to the technical field of solar cells, in particular to a solar cell passivation layer structure and a preparation method and application thereof. BACKGROUND

[0002] Improving efficiency and reducing cost is an eternal topic of photovoltaic development. With the development of solar cell technology, the efficiency limit caused by the structure of the passivated emitter and rear cell (PERC) has failed to meet the development needs of photovoltaic technology, and the tunnel oxide passivating contact (TOPCon) solar cell has a theoretical limit efficiency of 29.2%, better line compatibility, lower production cost, high yield and line stability, and has become a new generation of crystalline silicon solar cell structure to replace mass-produced PERC solar cells. However, the serious optical and electrical losses on the back surface of the cell have become a bottleneck restricting the further improvement of the efficiency of the cell, and the development of technology to improve the efficiency of the solar cell has been ongoing.

[0003] In order to further improve the efficiency of the solar cell, researchers have carried out research and development on the structure of the solar cell, mainly including TOPCon solar cells with double-sided passivation tunnel structures and various forms of x back contact (xBC) solar cells, such as: xBC solar cells with back contact (BC) structures of heterojunction solar cells (HIT) and BC structures of TOPCon solar cells. However, the development of the above-mentioned cell structures is based on low-level solar cell production processes, and more complex and more preparation processes are added, which will lead to continuous increase in line construction cost, production complexity and control degree, and there is no substantial progress in the technical level, but relies on the equipment provided by the supplier to continuously do addition and subtraction.

[0004] A HEMT device with a composite passivation layer structure is disclosed in Chinese patent literature, with the granted publication number CN216719952 U. The composite passivation layer structure composed of the first passivation layer and the second passivation layer stacked below the gate field plate can effectively suppress the current collapse effect. Compared with a single passivation layer of the same thickness, the composite passivation layer structure of the present application makes the parasitic capacitance of the device smaller, effectively improving the performance of the GaN-based high electron mobility transistor (HEMT) device. However, the composite passivation layer structure is not suitable for the above-mentioned general solar cell structure and cannot reduce the production cost. SUMMARY

[0005] In view of the above-mentioned disadvantages of the prior art, the purpose of the present application is to provide a solar cell passivation layer structure and its preparation method and application, for solving the problem that the improvement of the existing solar cell structure depends on the superposition of process equipment, has no substantial technical improvement, and has high production cost.

[0006] To achieve the above-mentioned purpose and other related purposes, the present application provides a preparation method of a solar cell passivation layer structure, comprising the following steps:

[0007] Step (1): depositing an aluminum oxide film layer on the surface of the substrate, and performing plasma treatment on the aluminum oxide film layer to obtain a modified aluminum oxide film layer;

[0008] Step (2): depositing an aluminum oxynitride film layer on the surface of the modified aluminum oxide film layer to form a double-layered structure;

[0009] Step (3): annealing the double-layered structure in a protective atmosphere to obtain the solar cell passivation layer structure.

[0010] More preferably, the substrate is a crystalline silicon substrate.

[0011] The iVoc of the aluminum oxide film layer deposited on the surface of the n-type single crystal silicon in the prior art is less than 710 mV. The present application found that the passivation of crystalline silicon by aluminum oxide is mainly dependent on the electric field formed by the negative fixed charges carried by the aluminum oxide, in addition to the chemical passivation of the interface between the aluminum oxide and the crystalline silicon. That is, the greater the density of negative fixed charges, the stronger the field effect passivation. The formation of negative fixed charges is related to the OH bonds and H bonds in the aluminum oxide. The more these two types of chemical bonds, the stronger the field effect passivation. Based on this principle, the present application creatively performs plasma treatment on the aluminum oxide film layer by combining the adsorption characteristics of the substance and the ionization and electric field acceleration of the plasma, so that the aluminum oxide itself adsorbs more OH bonds and H bonds with stronger binding energy. The iVoc of the obtained modified aluminum oxide film layer is greater than or equal to 720 mV. When applied to a single crystal silicon wafer with a pn junction, the iVoc is greater than or equal to 735 mV, while the iVoc of a conventional aluminum oxide film layer is less than 720 mV. The deposition of the aluminum oxynitride film layer on the surface of the modified aluminum oxide film layer is to enhance the passivation performance of the modified aluminum oxide film layer and the light absorption function of the solar cell. Although the early plasma treatment causes the continuous storage of OH bonds and H bonds in the modified aluminum oxide film layer, the double-layered structure formed by the modified aluminum oxide film layer and the aluminum oxynitride film layer does not have excellent passivation effect. The present application activates the fixed charges contained in the aluminum oxide by using an annealing process to make the OH bonds and H bonds in the modified aluminum oxide film layer move, thereby achieving the purpose of a large number of negative fixed charges carried by the aluminum oxide, and improving the passivation effect of the solar cell passivation layer structure.

[0012] Preferably, in step (1), the plasma treatment of the aluminum oxide film layer comprises plasma treatment during the deposition of the aluminum oxide film layer and plasma treatment after the deposition of the aluminum oxide film layer is completed.

[0013] The present application enables the aluminum oxide to adsorb more OH bonds and H bonds with stronger binding energy by secondary or multiple alternating plasma treatment during the deposition of the aluminum oxide film layer.

[0014] Preferably, in step (1), the plasma treatment uses plasma precursor gas selected from one or more of laughing gas, ammonia and hydrogen.

[0015] Preferably, in step (3), the annealing treatment has a temperature of 300-500℃ and an annealing time of 10-30min.

[0016] Preferably, the aluminum oxide film layer is deposited by thermal atomic layer deposition.

[0017] Preferably, the aluminum oxynitride film layer is deposited by plasma-assisted atomic layer deposition or plasma-enhanced chemical vapor deposition, which not only enables the aluminum oxynitride film layer to have a lower and adjustable refractive index, but also is beneficial to the light absorption of the subsequent solar cell and the activation of the passivation effect of the aluminum oxide after the subsequent annealing treatment.

[0018] Preferably, the deposition temperature of the aluminum oxide film layer and the aluminum oxynitride film layer is 120-300℃, which is low and has low energy consumption.

[0019] Preferably, in step (1), the deposition of the aluminum oxide film layer further comprises a substrate surface dangling bond chemical activity modification treatment, wherein the substrate surface dangling bond chemical activity modification treatment uses one or more of laughing gas, ammonia and hydrogen to treat the substrate.

[0020] The present application modifies the cleanliness of the crystal silicon substrate surface by plasma bombardment, and enables the dangling bonds of silicon atoms and dopant atoms to more easily form chemical passivation with oxygen elements in the aluminum oxide, which is beneficial to the subsequent deposition of the aluminum oxide film layer and enhances the chemical bonding rate of the constituent elements of the aluminum oxide film layer and the crystal silicon surface. Compared with the existing thermal ALD deposition of aluminum oxide, the present application uses the above technical means to achieve clean crystal silicon substrate surface while improving the chemical passivation properties of the aluminum oxide film layer. In addition, the substrate surface dangling bond chemical activity modification treatment also solves the problem of production cost waste caused by battery efficiency decline or rework due to the time required between different process steps (Q-time problem).

[0021] The present application also provides a solar cell passivation layer structure prepared by the above preparation method.

[0022] Preferably, the solar cell passivation layer structure comprises a modified alumina film layer and an aluminum oxynitride film layer deposited on the surface of the substrate in sequence, the modified alumina film layer is obtained by plasma treatment of an alumina film layer; the thickness of the modified alumina film layer is 8-15 nm, the refractive index of the aluminum oxynitride film layer ranges from 1.7 to 1.9, and the thickness of the aluminum oxynitride film layer is 2-5 nm.

[0023] The application further provides a use of the above-mentioned solar cell passivation layer structure in the preparation of a solar cell.

[0024] The application further provides a solar cell comprising the above-mentioned solar cell passivation layer structure.

[0025] Preferably, with the substrate as the reference, the solar cell comprises, from inside to outside towards the light-receiving side, a first diffusion junction with a conductive polarity opposite to that of the substrate, a first locally heavily doped emitter with a conductive polarity opposite to that of the substrate, the above-mentioned solar cell passivation layer structure, a first transparent conductive film layer and a first low-temperature electrode, the first transparent conductive film layer being in contact with the first locally heavily doped emitter; with the substrate as the reference, the solar cell comprises, from inside to outside towards the backside, a first locally heavily doped contact region with a conductive polarity same as that of the substrate, the above-mentioned solar cell passivation layer structure, a second transparent conductive film layer and a second low-temperature electrode, the second transparent conductive film layer being in contact with the first locally heavily doped contact region.

[0026] Preferably, the solar cell is a back contact solar cell.

[0027] Preferably, with the substrate as the reference, the solar cell comprises, from inside to outside towards the light-receiving side, the above-mentioned solar cell passivation layer structure and an antireflection layer insulating layer; with the substrate as the reference, the solar cell comprises, from inside to outside towards the backside, a second diffusion junction with a conductive polarity opposite to that of the substrate, a second locally heavily doped emitter, a second locally heavily doped contact region with a conductive polarity same as that of the substrate, the above-mentioned solar cell passivation layer structure and a third transparent conductive film layer, the third transparent conductive film layer being in contact with the second locally heavily doped contact region and the second locally heavily doped emitter.

[0028] The solar cell passivation layer structure and the transparent conductive film both have light conduction, refraction and absorption characteristics, and the combination thereof can not only achieve good passivation and transmission effects, but also avoid the poor light absorption property of the passivation tunnel layer structure represented by silicon material. The solar cell passivation layer structure is prepared in the same device, which greatly reduces the basic investment cost of different production devices and production lines, reduces the environmental pollution caused by multiple interruptions in the solar cell preparation process, and is beneficial to the yield and efficiency of the solar cell. The solar cell passivation layer structure is prepared based on the low-temperature preparation process, shallow junction doping and low-temperature contact process, which reduces the daily energy consumption of the device, and further prolongs the service life of the device hardware.

[0029] As described above, the solar cell passivation layer structure and the preparation method and application thereof have the following beneficial effects:

[0030] (1) The aluminum oxide film layer is subjected to plasma treatment, so that the aluminum oxide itself adsorbs more OH bonds and H bonds with stronger binding energy, the iVoc of the obtained modified aluminum oxide film layer is greater than or equal to 720 mV, the aluminum oxide film layer is deposited on the surface of the modified aluminum oxide film layer to enhance the passivation performance of the modified aluminum oxide film layer and the light absorption function of the solar cell, and the annealing process can move the OH bonds and H bonds in the modified aluminum oxide film layer, thereby activating the fixed charges contained in the aluminum oxide, and achieving the purpose of a large number of negative fixed charges on the aluminum oxide.

[0031] (2) In the solar cell using the solar cell passivation layer structure, the solar cell passivation layer structure and the transparent conductive film both have light conduction, refraction and absorption characteristics, and the combination thereof can not only achieve good passivation and transmission effects, but also avoid the poor light absorption property of the passivation tunnel layer structure represented by silicon material. The solar cell passivation layer structure is prepared in the same device, and is combined with the low-temperature preparation process, shallow junction doping and low-temperature contact process, which not only reduces the production cost and prolongs the service life of the device hardware, but also reduces the environmental pollution caused by multiple interruptions in the solar cell preparation process, and is beneficial to the yield and efficiency of the solar cell. BRIEF DESCRIPTION OF DRAWINGS

[0032] FIG. 1 shows a schematic diagram of the solar cell passivation layer structure prepared in Example 1.

[0033] FIG. 2 shows a schematic diagram of the structure of the solar cell prepared in Example 1.

[0034] FIG. 3 shows a schematic diagram of the structure of the solar cell prepared in Example 2.

[0035] Figure 4 shows a schematic diagram of the structure of a solar cell prepared in Example 3.

[0036] BRIEF DESCRIPTION OF DRAWINGS: substrate 1, modified alumina film layer 2, aluminum oxynitride film layer 3, first diffusion junction 4, first locally heavily doped emitter 5, first transparent conductive film layer 6, first low temperature electrode 7, first locally heavily doped contact region 8, second transparent conductive film layer 9, second low temperature electrode 10, antireflection layer insulating layer 11, second diffusion junction 12, second locally heavily doped emitter 13, second locally heavily doped contact region 14, third transparent conductive film layer 15. DETAILED DESCRIPTION

[0037] The present application will be described in greater detail by way of specific embodiments, and as such, those skilled in the art can easily understand other advantages and purposes of the present application from the description disclosed herein. The present application can also be implemented or applied in other different embodiments, and the details in the description can be modified or changed based on different views and applications without departing from the spirit of the present application.

[0038] It should be noted that the process equipment or device not specifically mentioned in the following examples is the conventional equipment or device in the art.

[0039] In addition, it should be understood that the one or more method steps mentioned in the present application do not exclude the presence of other method steps before and after the combination steps or the insertion of other method steps between the explicitly mentioned steps, unless otherwise specified; it should also be understood that the combination connection relationship between the one or more devices / apparatuses mentioned in the present application does not exclude the presence of other devices / apparatuses before and after the combination devices / apparatuses or the insertion of other devices / apparatuses between the two explicitly mentioned devices / apparatuses, unless otherwise specified. Moreover, unless otherwise specified, the numbering of each method step is only a convenient tool for identifying each method step, and is not intended to limit the arrangement order of each method step or to limit the range of implementation of the present application, and the change or adjustment of the relative relationship without substantial change of the technical content is also considered as the scope of implementation of the present application.

[0040] The substrate used in the following examples of the present application is crystalline silicon.

[0041] The passivation effect test of the passivation layer structure of the solar cell in the following examples of the present application is carried out by using double-side polished and textured silicon wafer, and the test instrument is Sintion WCT 120 minority carrier lifetime tester.

[0042] Example 1

[0043] The present application provides a preparation method of a passivation layer structure of a solar cell, which is prepared by using a one-plate time-type PE-ALD device, and includes the following steps:

[0044] Step (1): depositing an aluminum oxide film layer on the surface of the substrate, and performing plasma treatment on the aluminum oxide film layer to obtain a modified aluminum oxide film layer:

[0045] The crystalline silicon substrate was placed in a reaction furnace of a plate-type time-type plasma-enhanced atomic layer deposition (PE-ALD) device, vacuumized, and subjected to surface dangling bond chemical activity modification treatment by introducing plasma precursor gas laughing gas and hydrogen. The flow rate of the laughing gas was 2000 seem, the flow rate of the hydrogen was 4000 seem, the reaction pressure was 180 Pa, the power source used was 40 kHz, the discharge power was 3000 W, the on / off ratio was 1 / 10, the process temperature was 120 DEG C, and the treatment time was 2 min.

[0046] The aluminum oxide film layer was deposited by thermal atomic layer deposition at 120 DEG C, the gas source was TMA and water, the gas flow rate was 2000 seem, the source pressure was 50 Pa, the nitrogen purge flow rate was 5000 seem, and the deposited film layer thickness was 4 nm.

[0047] After the deposition of the aluminum oxide, the passivation performance of the aluminum oxide film layer was modified by plasma. The discharge gas was laughing gas and ammonia, the gas flow rates were 2000 seem and 4000 seem respectively, the reaction pressure was 180 Pa, the power source used was 40 kHz, the discharge power was 4000 W, the on / off ratio was 1 / 20, the process temperature was 120 DEG C, and the treatment time was 2 min.

[0048] Then, the aluminum oxide film layer was deposited again by thermal atomic layer deposition at 120 DEG C, the gas source was TMA and water, the gas flow rate was 2000 seem, the source pressure was 50 Pa, the nitrogen purge flow rate was 5000 seem, and the deposited film layer thickness was 4 nm.

[0049] Then, the passivation performance of the aluminum oxide film layer was modified again by plasma. The discharge gas was laughing gas and ammonia, the gas flow rates were 2000 seem and 4000 seem respectively, the reaction pressure was 180 Pa, the power source used was 40 kHz, the discharge power was 4000 W, the on / off ratio was 1 / 20, the process temperature was 120 DEG C, and the treatment time was 2 min. A modified aluminum oxide film layer with a thickness of 8 nm was obtained on the surface of the crystalline silicon substrate.

[0050] Step (2): depositing an aluminum nitride oxide film layer on the surface of the modified aluminum oxide film layer to form a double-layered structure:

[0051] The aluminum oxynitride film layer is deposited by plasma assisted atomic layer deposition at 120°C, using ammonia gas, laughing gas and TMA as the gases, with a flow rate of 3000 sccm, 2000 sccm and 2000 sccm respectively, a power supply of 40 kHz, a discharge power of 4000 W, a switch ratio of 1 / 20, a pressure of 180 Pa, a TMA inlet pressure of 50 Pa, and a nitrogen purge flow rate of 5000 sccm; the refractive index of the aluminum oxynitride film layer is 1.7, and the thickness is 2 nm;

[0052] Step (3): annealing the double-layered structure under a nitrogen protective atmosphere, with an annealing temperature of 300°C, a nitrogen flow rate of 5000 sccm, a pressure of 800 Pa, and an annealing time of 30 min, to obtain the solar cell passivation layer structure.

[0053] As shown in FIG. 1, the application also provides a solar cell passivation layer structure prepared by the above preparation method, which comprises a modified aluminum oxide film layer 2 and an aluminum oxynitride film layer 3 deposited on the surface of a substrate 1 in sequence, wherein the modified aluminum oxide film layer is obtained by plasma treatment of an aluminum oxide film layer; the thickness of the modified aluminum oxide film layer is 8 nm, the refractive index of the aluminum oxynitride film layer is 1.7, and the thickness of the aluminum oxynitride film layer is 2 nm.

[0054] The application also provides a preparation method of a solar cell comprising the above solar cell passivation layer structure, comprising the following steps:

[0055] (1) cleaning and texturing the surface of 10000 pieces of p-type monocrystalline silicon with a size of 182mm*182mm, a resistivity of 0.5 -1 Ω·cm and a thickness of 130μm by using a chemical solvent;

[0056] (2) placing the textured silicon wafer into a boron diffusion furnace to deposit a boron-doped silicon oxide (BSG) film layer on the back surface thereof, wherein the thickness of the BSG film layer is 120nm;

[0057] (3) performing selective shallow-junction heavy doping on the silicon wafer with the BSG film layer deposited on the back surface thereof by laser, wherein the highest doping concentration is 5E19 / cm 3 , the doping depth is 150nm, and the heavy doping width is 50μm;

[0058] (4) removing the BSG film layer on the front surface and the edge of the wafer by chain cleaning, and removing the BSG layer on the front surface and the edge of the wafer by tank cleaning;

[0059] (5) placing the cleaned surface into a phosphorus diffusion furnace to deposit a phosphorus-doped silicon oxide (PSG) film layer, wherein the thickness of the PSG film layer is 10nm, and deep-junction diffusion is performed, with a highest diffusion depth of 2E20 / cm 3 and a junction depth of 50nm;

[0060] (6) Subsequently, the front surface of the silicon wafer on which the PSG film layer is deposited is subjected to selective shallow junction doping by laser, and the highest concentration of phosphorus in the selectively doped region is 5E20 / cm 3 , the junction depth is 50 nm, and the width of the selectively doped region is 50 μm;

[0061] (7) The side edge PSG film layer is removed by using a chain type low-concentration HF, and the side edge phosphorus diffusion is removed by alkaline washing, and then the PSG film layer and the BSG film layer on the front and back surfaces are removed by slot type HF;

[0062] (8) The above-mentioned passivation layer structure (total thickness 10 nm) of the solar cell is deposited on both surfaces, and the film forming method is as described above;

[0063] (9) Both surfaces are subjected to selective laser opening, the opening position and the opening width of the back surface are the same as those of the heavily doped region in (3), and the opening position and the opening width of the front surface are the same as those of the selectively doped region in (6);

[0064] (10) The indium-doped tin oxide film layer is deposited by using a plasma-assisted atomic layer deposition device, the film thickness is 80 nm, and the square resistance is 40 Ω / sq;

[0065] (11) The low-temperature electrode is prepared by printing a low-temperature paste, and the process temperature is 180°C;

[0066] (12) Light injection and laser-assisted passivation contact.

[0067] As shown in FIG. 2, the application also provides a solar cell with a double-sided texturing structure prepared by the above preparation method. With the substrate 1 as a reference, the solar cell towards the light-receiving side comprises, from inside to outside, a first diffusion junction 4 opposite in conductive polarity to the substrate, a first local heavily doped emitter 5 opposite in conductive polarity to the substrate, a modified aluminum oxide film layer 2, an aluminum oxynitride film layer 3, a first transparent conductive film layer 6, and a first low-temperature electrode 7, the first transparent conductive film layer being in contact with the first local heavily doped emitter. With the substrate 1 as a reference, the solar cell towards the back light side comprises, from inside to outside, a first local heavily doped contact region 8 same in conductive polarity to the substrate, the modified aluminum oxide film layer 2, the aluminum oxynitride film layer 3, a second transparent conductive film layer 9, and a second low-temperature electrode 10, the second transparent conductive film layer being in contact with the first local heavily doped contact region. Wherein, the substrate 1 is a p-type crystalline silicon substrate, the first diffusion junction 4 is an n-type diffusion junction, the first transparent conductive film layer 6 and the second transparent conductive film layer 9 are indium-doped tin oxide film layers, the first local heavily doped emitter 5 is an n-type heavily doped emitter, and the first local heavily doped contact region 8 is a p-type heavily doped contact region.

[0068] Comparative Example 1

[0069] The preparation method of the aluminum oxide film layer in the present comparative example is as follows:

[0070] First, the surface of the cleaned n-type monocrystalline silicon is pretreated by ozone to clean the residual organic matter on the surface of the silicon wafer and deposit a thin layer of about 1 nm of silicon oxide on the surface of the silicon to assist the chemical passivation of aluminum oxide; then 10 nm of aluminum oxide is deposited on the surface of the silicon oxide by water and TMA, and the annealing temperature is 500°C and the annealing time is more than 30 min.

[0071] The present comparative example prepares a TOPCon solar cell according to the preparation process of the TOPCon solar cell structure for mass production, and the main steps are as follows:

[0072] (1) The surface of 10,000 pieces of n-type monocrystalline silicon with a resistivity of 0.5-1 Ω·cm and a thickness of 130 μm is cleaned and textured by a chemical solvent;

[0073] (2) Boron diffusion: the textured silicon wafer is placed in a boron diffusion furnace to deposit a BSG film layer on the back surface and perform joint pushing, the thickness of the BSG film layer is 120 nm, the diffusion sheet resistance is 400 Ω / sq, and the junction depth is 0.75 μm;

[0074] (3) Chain type edge and back surface BSG film layer removal, slot type back surface and side edge diffusion removal, and back surface alkali polishing with a reflectivity of 40%;

[0075] (4) 1-2 nm of tunneling oxide layer and 130 nm of phosphorus-doped poly-Si film layer are deposited on the back surface of the silicon wafer by plasma-enhanced chemical vapor deposition, and 30 nm of PSG film layer is deposited;

[0076] (5) The silicon wafer is annealed at 920°C for 20 min;

[0077] (6) Chain type cleaning to remove the edge and front surface PSG, and slot type front surface and side edge phosphorus-doped poly-Si film layer plating, followed by slot type HF to remove the front surface BSG film layer and the back surface PSG film layer;

[0078] (7) 4 nm of aluminum oxide film layer is deposited on the front surface of the silicon wafer by thermal atomic layer deposition;

[0079] (8) 80 nm of silicon oxynitride stack film with a refractive index of 1.95-2.02 is deposited on the front surface of the silicon wafer by plasma-enhanced chemical vapor deposition;

[0080] (9) 80 nm of silicon nitride stack film with a refractive index of 1.98-2.05 is deposited on the back surface of the silicon wafer by plasma-enhanced chemical vapor deposition;

[0081] (10) Front and back printing high-temperature paste preparation electrode;

[0082] (11) Light injection and laser-assisted sintering.

[0083] The passivation effect of the passivation layer structure of the solar cell of Example 1 and Comparative Example 1 was tested, and the results are shown in Table 1:

[0084] Table 1. Passivation data of the passivation layer structure of the solar cell prepared by Example 1 and Comparative Example 1

[0085]

[0086] In Table 1: iVoc is the ideal open circuit voltage, which represents the passivation of the solar cell, and the larger the value, the better the passivation.

[0087] As can be seen from Table 1: under the same thickness condition (10 nm), the iVoc of the conventional aluminum oxide film layer passivation layer structure of Comparative Example 1 can only reach 708 mV, while the passivation film layer structure of the double-sided modified aluminum oxide film layer and aluminum oxynitride film layer used in the present application can achieve 723 mV.

[0088] The performance of the solar cell of Example 1 and Comparative Example 1 was tested, and the results are shown in Table 2:

[0089] Table 2. Performance data of the solar cell prepared by Example 1 and Comparative Example 1

[0090]

[0091] In Table 2: Voc is the open circuit voltage of the solar cell, Isc is the short circuit current of the solar cell, FF is the fill factor of the solar cell, and Eff is the photoelectric conversion efficiency of the solar cell. These four factors represent important electrical performance parameters of the solar cell for light-induced electricity.

[0092] Compared with the preparation process of the TOPCon solar cell, the preparation process of the above-mentioned solar cell structure of the embodiment is less low-pressure chemical vapor deposition (600 DEG C process temperature) or plasma-enhanced chemical vapor deposition (450 DEG C process temperature) for depositing the tunnel layer and the poly-Si film layer, less traditional ALD (250 DEG C process temperature) equipment, less plasma-enhanced chemical vapor deposition (500 DEG C process temperature) for depositing silicon nitride on the front and back surfaces, and a total of four less equipment. The four kinds of equipment are replaced by two laser selective doping equipment (room temperature), one laser opening equipment (room temperature), one passivation film preparation equipment (can be simultaneously coated on the front and back surfaces) (maximum 400 DEG C), and one plasma-assisted atomic layer deposition equipment (100 DEG C). In terms of equipment types, more is added, and the environmental problem caused by improper dust treatment of the plasma-enhanced chemical vapor deposition for preparing the poly-Si film layer is reduced.

[0093] As can be seen from Table 2, the solar cell prepared by using the passivation layer structure of the solar cell of the application has high open-circuit voltage and high fill factor, which reflects that the passivation property of the passivation layer structure selected in the application is not weaker than the passivation effect of the passivation tunnel layer structure in the TOPCon solar cell, and the low short-circuit current is mainly related to the low utilization rate of back surface reflected light of the back surface texturing structure.

[0094] Embodiment 2

[0095] The embodiment of the application provides a preparation method of a solar cell passivation layer structure, which is prepared by using a one-plate time type PE-ALD equipment, and comprises the following steps:

[0096] Step (1): depositing an aluminum oxide film layer on the surface of the substrate, and performing plasma treatment on the aluminum oxide film layer to obtain a modified aluminum oxide film layer:

[0097] The crystalline silicon substrate is placed in the reaction furnace of the one-plate time type PE-ALD equipment, vacuumized, and the surface dangling bond chemical activity modification treatment of the crystalline silicon substrate is performed by introducing plasma precursor gases laughing gas and ammonia gas, the flow rate of the laughing gas is 2000 sccm, the flow rate of the ammonia gas is 3000 sccm, the reaction pressure is 180 Pa, the power supply used is 40 kHz, the discharge power is 3000 W, the on-off ratio is 1 / 15, the process temperature is 210 DEG C, and the treatment time is 2 min;

[0098] After the plasma treatment, the aluminum oxide film layer is deposited by the hot atomic layer deposition method at 210 DEG C, the gas source is TMA and water, the gas flow rate is 2000 sccm, the source pressure is 50 Pa, the nitrogen sweeping flow rate is 5000 sccm, and the thickness of the deposited film layer is 11.5 nm;

[0099] After the deposition of the aluminum oxide, the passivation performance of the aluminum oxide film layer is modified by plasma, the discharge gas is laughing gas and hydrogen, the gas flow is 2000sccm and 4000sccm respectively, the reaction pressure is 180pa, the power supply used is 40kHz, the discharge power is 4000W, the on-off ratio is 1 / 10, the process temperature is 210℃, and the processing time is 3min; the modified aluminum oxide film layer is obtained;

[0100] Step (2): depositing an aluminum oxynitride film layer on the surface of the modified aluminum oxide film layer to form a double-layered structure:

[0101] The aluminum nitride film layer is deposited at 210℃ by plasma-assisted atomic layer deposition, the refractive index of the film layer is 1.8, and the thickness is 3.5nm; the gases used are ammonia, hydrogen and TMA, the deposition gas flow rates are 3000sccm, 4000sccm and 2000sccm respectively, the power supply used for discharge is 40kHz, the discharge power is 4000W, the on-off ratio is 1 / 15, the pressure is 180Pa, the TMA inlet pressure is 50pa, and the nitrogen purge flow rate is 5000sccm;

[0102] Step (3): annealing the layered film deposited with the modified aluminum oxide film layer and the aluminum oxynitride film layer in a nitrogen atmosphere, the annealing temperature is 400℃, the nitrogen flow rate is 5000sccm, the pressure is 800pa, and the annealing time is 20min, thereby obtaining a solar cell passivation layer structure.

[0103] The application also provides a solar cell passivation layer structure prepared by the above preparation method, which comprises a modified aluminum oxide film layer and an aluminum oxynitride film layer deposited on the surface of a substrate in sequence, the modified aluminum oxide film layer is obtained by plasma treatment of an aluminum oxide film layer; the thickness of the modified aluminum oxide film layer is 11.5nm, the refractive index of the aluminum oxynitride film layer is 1.8, and the thickness of the aluminum oxynitride film layer is 3.5nm.

[0104] The application also provides a preparation method of a solar cell comprising the above solar cell passivation layer structure, which comprises the following steps:

[0105] (1) cleaning and texturing the surface of 10000 pieces of n-type monocrystalline silicon with a size of 182mm*182mm, a resistivity of 0.5 -1 Ω·cm and a thickness of 130μm by a chemical solvent;

[0106] (2) placing the textured silicon wafer into a boron diffusion furnace, depositing a BSG film layer on the front surface of the silicon wafer, and bonding, the thickness of the BSG film layer is 120nm, the junction depth is 100nm, and the square resistance is 500Ω / sq;

[0107] (3) The silicon wafer with BSG film layer on the front side is selectively shallowly doped by laser, the highest concentration of the doping is 5E19 / cm 3 , the doping depth is 150 nm, and the width of the heavy doping is 50 μm;

[0108] (4) The BSG film layer on the back side and the edge is removed by chain cleaning, the film layer on the back side and the edge is removed by slot cleaning, the back side is alkali polished, and the reflectivity is 40%;

[0109] (5) The silicon wafer is put into a phosphorus diffusion furnace to deposit a PSG film layer on the alkali polished surface, and the thickness of the PSG film layer is 10 nm;

[0110] (6) The back side of the silicon wafer with the PSG film layer is selectively shallowly doped by laser, the highest concentration of the selective doping area is 5E20 / cm 3 , the depth of the junction is 50 nm, and the width of the selective area is 50 μm;

[0111] (7) The PSG film layer on the side edge is removed by chain low-concentration HF, and the phosphorus diffusion on the side edge is removed by alkali cleaning, and then the PSG film layer and the BSG film layer on the front and back sides are removed by slot HF;

[0112] (8) The above-mentioned passivation layer structure (total thickness 15 nm) of the solar cell is deposited on both sides, and the film forming mode is as described above;

[0113] (9) The selective laser opening is performed on both sides, the opening position and the opening width of the back side are the same as those of the heavy doping area in (3), and the opening position and the opening width of the front side are the same as those of the selective doping area in (6);

[0114] (10) The indium-doped tin oxide film layer is deposited by using a plasma-assisted atomic layer deposition device, the thickness of the film layer is 80 nm, and the square resistance is 45 Ω / sq;

[0115] (11) The low-temperature electrode is prepared by printing low-temperature paste, and the process temperature is 180°C;

[0116] (12) Light injection and laser-assisted passivation contact.

[0117] As shown in FIG. 3, the application also provides a solar cell, a front emitter and a back polishing structure prepared by the above preparation method. With the substrate 1 as a reference, the solar cell includes, from inside to outside, a first diffusion junction 4 opposite in conductive polarity to the substrate, a first local heavy-doped emitter 5 opposite in conductive polarity to the substrate, a modified aluminum oxide film layer 2, an aluminum oxynitride film layer 3, a first transparent conductive film layer 6 and a first low-temperature electrode 7 toward the light-receiving side of the solar cell, the first transparent conductive film layer being in contact with the first local heavy-doped emitter; and the solar cell includes, from inside to outside, a first local heavy-doped contact region 8 same in conductive polarity to the substrate, the modified aluminum oxide film layer 2, the aluminum oxynitride film layer 3, a second transparent conductive film layer 9 and a second low-temperature electrode 10 toward the back side of the solar cell, the second transparent conductive film layer being in contact with the first local heavy-doped contact region. The substrate 1 is an n-type crystalline silicon substrate, the first diffusion junction 4 is a p-type diffusion junction, the first transparent conductive film layer 6 and the second transparent conductive film layer 9 are indium-doped tin oxide film layers, the first local heavy-doped emitter 5 is a p-type heavy-doped emitter, and the first local heavy-doped contact region 8 is an n-type heavy-doped contact region.

[0118] Comparative Example 2

[0119] The comparative example is prepared by a conventional thermal atomic layer deposition of an aluminum oxide film layer in the following manner:

[0120] First, the surface of a cleaned p-type single crystal silicon is subjected to ozone pretreatment to clean the organic residues on the surface of the silicon wafer and deposit a thin layer of about 1 nm of silicon oxide on the surface of the silicon to assist the chemical passivation of the aluminum oxide; then, 15 nm of aluminum oxide is deposited on the surface of the silicon oxide by water and TMA, the annealing temperature is 500°C, and the annealing time is more than 30 min.

[0121] The comparative example is prepared according to the preparation process of a mass-produced TOPCon solar cell structure, and the main steps are as follows:

[0122] (1) The surface of 10,000 pieces of n-type single crystal silicon with a resistivity of 0.5 -1 Ω·cm and a thickness of 130 μm is cleaned and textured by a chemical solvent;

[0123] (2) Boron diffusion: the textured silicon wafer is placed in a boron diffusion furnace to deposit a BSG film layer on the back surface and perform a push junction, the thickness of the BSG film layer is 120 nm, the diffusion sheet resistance is 400 Ω / sq, and the junction depth is 0.75 μm;

[0124] (3) Chain type edge and back BSG film layer are removed, groove type is used to remove the back and side edge diffusion, and the back is subjected to alkali polishing, and the reflectivity is 40%

[0125] (4) Depositing 1-2 nm tunneling oxide layer and 130 nm phosphorus-doped poly-Si film layer on the back surface of the silicon wafer by plasma enhanced chemical vapor deposition, and depositing 30 nm PSG film layer;

[0126] (5) Annealing the silicon wafer at 920 ℃ for 20 min;

[0127] (6) Removing the edge and front PSG film layer by chain cleaning, and removing the front and side phosphorus-doped poly-Si film layer by slot plating, and then removing the front BSG film layer and the back PSG film layer by slot HF;

[0128] (7) Depositing 4 nm aluminum oxide film layer on the front surface of the silicon wafer by thermal atomic layer deposition;

[0129] (8) Depositing 80 nm silicon oxynitride film with a refractive index of 1.95-2.02 on the front surface of the silicon wafer by plasma enhanced chemical vapor deposition;

[0130] (9) Depositing 80 nm silicon nitride film on the back surface of the silicon wafer by plasma enhanced chemical vapor deposition;

[0131] (10) Preparing electrodes by printing high-temperature paste on the front and back surfaces;

[0132] (11) Light injection and laser-assisted sintering.

[0133] The passivation effects of the passivation layer structures of the solar cells of Example 2 and Comparative Example 2 were tested, and the results are shown in Table 3:

[0134] Table 3. Passivation data of the passivation layer structures of the solar cells prepared in Example 2 and Comparative Example 2

[0135]

[0136] In Table 3: iVoc is the ideal open-circuit voltage, which represents the passivation of the solar cell, and the larger the value, the better the passivation.

[0137] As can be seen from Table 3: under the same thickness condition (15 nm), the double-sided deposition of the symmetrical structure film layer on the same resistivity and conductivity type silicon wafer, the iVoc of the aluminum oxide film layer passivation layer structure of Comparative Example 2 can only reach 704 mV, while the passivation film layer structure of the double-sided modified aluminum oxide film layer and aluminum oxynitride film layer of the present application can achieve 720 mV.

[0138] The performance of the solar cells of Example 2 and Comparative Example 2 was tested, and the results are shown in Table 4:

[0139] Table 4. Performance data of the solar cells prepared in Example 2 and Comparative Example 2

[0140]

[0141] In Table 4: Voc is the open-circuit voltage of the solar cell, Isc is the short-circuit current of the solar cell, FF is the fill factor of the solar cell, and Eff is the photoelectric conversion efficiency of the solar cell. These four factors represent important electrical performance parameters of the solar cell for photovoltaic power generation.

[0142] Comparison of solar cell structures of Example 2 and Comparative Example 2:

[0143] Process comparison: Compared with the preparation process of the TOPCon solar cell, the preparation process of the above-described solar cell structure is less low-pressure chemical vapor deposition (600 DEG C process temperature) or plasma-enhanced chemical vapor deposition (450 DEG C process temperature) for depositing the tunnel layer and the poly-Si film layer, less traditional ALD (250 DEG C process temperature) equipment, less plasma-enhanced chemical vapor deposition (500 DEG C process temperature) for depositing silicon nitride on the front and back surfaces, and a total of four less equipment. The four types of equipment are replaced by two laser selective doping equipment (room temperature), one laser opening equipment (room temperature), one passivation film preparation equipment (can be used for simultaneous film deposition on the front and back surfaces) (maximum 400 DEG C), and one plasma-assisted atomic layer deposition equipment (100 DEG C). In terms of equipment types, more equipment is added, but as can be seen from the process temperature, the energy consumption of the equipment is greatly reduced, and the environmental problems caused by improper dust treatment of the plasma-enhanced chemical vapor deposition for preparing the poly-Si film layer are eliminated.

[0144] Comparison of electrical performance parameters: As can be seen from Table 4, the solar cell prepared by the cell structure in the present embodiment has high open-circuit voltage, short-circuit current, and high fill factor, which reflects that the passivation property of the passivation film layer selected in the present application is not weaker than the passivation effect of the passivation tunnel layer structure in the TOPCon.

[0145] Example 3

[0146] The present application provides a preparation method of a passivation layer structure of a solar cell, which is prepared by using a one-plate time-type PE-ALD equipment, and includes the following steps:

[0147] Step (1): depositing an aluminum oxide film layer on the surface of the substrate, and performing plasma treatment on the aluminum oxide film layer to obtain a modified aluminum oxide film layer:

[0148] The crystal silicon substrate is placed in a reaction furnace of a plate type time type PE-ALD device, vacuumized, and subjected to surface dangling bond chemical activity modification treatment by introducing plasma precursor gases of hydrogen and ammonia, the flow rate of the hydrogen is 2000sccm, the flow rate of the ammonia is 4000sccm, the reaction pressure is 220pa, the power source used is 40kHz, the discharge power is 6000W, the on / off ratio is 1 / 15, the process temperature is 300℃, and the treatment time is 2min;

[0149] After the plasma treatment, an aluminum oxide film layer is deposited by a thermal atomic layer deposition method at 300℃, the gas source is TMA and water, the flow rate of the gas is 2000sccm, the source pressure is 50pa, the nitrogen blowing flow rate is 5000sccm, and the deposited film layer thickness is 15nm;

[0150] The passivation performance of the aluminum oxide film layer is modified by plasma, the discharge gas is ammonia and hydrogen, the gas flow rate is 2000sccm and 4000sccm respectively, the reaction pressure is 220pa, the power source used is 40kHz, the discharge power is 4000W, the on / off ratio is 1 / 10, the process temperature is 300℃, the treatment time is 3min, and a modified aluminum oxide film layer is obtained;

[0151] Step (2): depositing an aluminum oxynitride film layer on the surface of the modified aluminum oxide film layer to form a double-layered structure:

[0152] The silicon oxynitride film layer is deposited by a plasma enhanced chemical vapor deposition method at 300℃, the film layer refractive index is 1.9, and the thickness is 5nm; the gas used is laughing gas, silane, and ammonia, the deposition gas flow rate is 3000sccm, 900sccm, and 3000sccm respectively, the power source used for discharge is 40kHz, the discharge power is 4000W, the on / off ratio is 1 / 15, and the pressure is 180Pa;

[0153] Step (3): annealing the layered film on which the modified aluminum oxide film layer and the aluminum oxynitride film layer are deposited under a nitrogen atmosphere, the annealing temperature is 500℃, the nitrogen flow rate is 5000sccm, the pressure is 800Pa, and the annealing time is 10min, thereby obtaining a solar cell passivation layer structure.

[0154] The application also provides a solar cell passivation layer structure prepared by the above preparation method, which comprises a modified aluminum oxide film layer and an aluminum oxynitride film layer deposited on the surface of a substrate in sequence, the modified aluminum oxide film layer is obtained by plasma treatment on an aluminum oxide film layer; the thickness of the modified aluminum oxide film layer is 15nm, the refractive index of the aluminum oxynitride film layer is 1.9, and the thickness of the aluminum oxynitride film layer is 5nm.

[0155] The application further provides a preparation method of the solar cell containing the solar cell passivation layer structure.

[0156] (1) polish the surface of 10000 pieces of n-type monocrystalline silicon with a size of 182mm*182mm, a resistivity of 1.5 -2 Ω·cm and a thickness of 150μm by using a chemical solvent;

[0157] (2) place the polished silicon wafer into a boron diffusion furnace, deposit BSG film layers on both sides of the silicon wafer, and perform a push junction with a junction depth of 200nm and a maximum surface doping concentration of 5E18 / cm 3 , and the BSG thickness is 120nm;

[0158] (3) perform selective shallow junction heavy doping on the back surface of the silicon wafer with deposited BSG film layers by using laser, the maximum doping concentration is 5E19 / cm 3 , the doping depth is 200nm, and the heavy doping width is 50μm;

[0159] (4) selectively etch and remove the BSG film layers in the shallow doping area on the back surface by using laser equipment, and the laser etching width is 40μm;

[0160] (5) remove the boron doping layer in the area where the BSG film layers are removed by laser selective etching on the back surface by using slot cleaning;

[0161] (6) place the silicon wafer into a phosphorus diffusion furnace to deposit PSG film layers on the back surface, and the PSG film layer thickness is 25nm; since the n-type silicon in the area where the BSG film layers are selectively removed by laser in the step 5) is exposed, and the other areas have 120nm BSG film layers as a mask, therefore, only the exposed area is effectively deposited and pushed by PSG, and the doping concentration is 5E20 / cm 3 , and the junction depth is 50nm;

[0162] (7) perform laser segmentation on the p-type area and the junction area between the n-type area on the back surface by using laser, and the laser scribing width is 35μm;

[0163] (8) remove the boron-phosphorus co-doped silicon oxide layer on the side edges and the front surface by using a chain, remove the B diffusion layer on the front surface and the side edges and the B-doped silicon in the segmentation area between the p-type area and the n-type area on the back surface by using slot cleaning, and perform texturing and then remove the PSG film layer and the BSG film layer on the back surface by using slot HF;

[0164] (9) deposit the above solar cell passivation layer structure (total thickness 20nm) on both sides, and the film forming mode is as described above;

[0165] (10) backside selective laser drilling, the position and width of the backside drilling are the same as the laser processing pattern and position in (3) and (4);

[0166] (11) depositing an indium-doped tin oxide film layer on the backside by using a plasma-assisted atomic layer deposition device, the thickness of the film layer is 80 nm, and the square resistance is 45 Ω / sq;

[0167] (12) laser cutting of the transparent conductive film layer at the junction between the p-type region and the n-type region by using a laser;

[0168] (13) depositing a silicon oxide anti-reflection film layer on the front side by using a plasma-enhanced chemical vapor deposition device, the thickness of the film layer is 70 nm, and the refractive index is 1.72;

[0169] (14) printing a low-temperature paste to prepare a low-temperature electrode on the backside, the process temperature is 180 ℃;

[0170] (15) photo-injection and laser-assisted passivation contact.

[0171] As shown in FIG. 4, the application also provides a back contact solar cell prepared by the preparation method, which comprises, from inside to outside, a modified aluminum oxide film layer 2, an aluminum oxynitride film layer 3 and an anti-reflection layer insulating layer 11 on the light-receiving side of the solar cell with the substrate 1 as a reference; and comprises, from inside to outside, a local second diffusion junction 12 with a conductive polarity opposite to that of the substrate, a second local heavily doped emitter 13, a second local heavily doped contact region 14 with a conductive polarity same as that of the substrate, the modified aluminum oxide film layer 2, the aluminum oxynitride film layer 3 and a third transparent conductive film layer 15 on the backside of the solar cell with the substrate 1 as a reference, the third transparent conductive film layer being in contact with the second local heavily doped contact region and the second local heavily doped emitter. The substrate 1 is an n-type crystalline silicon substrate, the second diffusion junction 12 is a p-type diffusion junction, the second local heavily doped emitter 13 is a p-type boron-doped heavily doped emitter, the second local heavily doped contact region 14 is an n-type phosphorus-doped heavily doped contact region, the third transparent conductive film layer 15 is an indium-doped tin oxide film layer, and the anti-reflection layer insulating layer 11 is a silicon oxide layer.

[0172] Comparative Example 3

[0173] The comparative example is prepared by a traditional thermal atomic layer deposition of an aluminum oxide film layer:

[0174] First, the surface of a cleaned n-type single crystal silicon is subjected to ozone pretreatment to clean the organic residues on the surface of the silicon wafer and deposit a thin layer of about 1 nm of silicon oxide on the surface of the silicon to assist the chemical passivation of the aluminum oxide; then, 20 nm of aluminum oxide is deposited on the surface of the silicon oxide by using water and TMA, the annealing temperature is 500 ℃, and the annealing time is more than 30 min.

[0175] The present comparative example prepared a TBC solar cell according to the preparation process of a currently mass-produced TBC solar cell, the main steps being as follows:

[0176] (1) 10,000 pieces of n-type monocrystalline silicon with a resistivity of 1.5 -2 Ω·cm and a thickness of 150 μm were subjected to surface polishing by a chemical solvent;

[0177] (2) The polished silicon wafer was placed into a boron diffusion furnace, BSG film layers were deposited on both sides of the silicon wafer, and the junction was pushed, with a junction depth of 200 nm and a maximum surface doping concentration of 5E18 / cm 3 , and a BSG thickness of 120 nm;

[0178] (3) The backside part of the BSG film layer was removed by selective etching by a laser device, with a laser etching width of 500 μm;

[0179] (4) The boron-doped layer in the area where the BSG film layer was removed by laser selective etching on the backside was removed by slot cleaning;

[0180] (5) The silicon wafer was placed into a plasma-enhanced chemical vapor deposition device to prepare a 1-2 nm tunneling oxide layer and a 150 nm phosphorus-doped polysilicon film layer, and then a 30 nm silicon oxide film layer (PSG) was deposited on the surface thereof;

[0181] (6) The silicon wafer was placed into an annealing furnace to activate and crystallize the deposited phosphorus-doped polysilicon, with an annealing temperature of 920 °C and an annealing time of 20 min;

[0182] (7) The PSG on the surface of the backside boron-diffused area was etched by laser, and then the phosphorus-doped poly-Si film layer and the tunneling layer in the junction area between the p-type region and the n-type region on the backside were removed by laser scribing with a scribing width of 35 μm;

[0183] (8) After the side edges and the front side were removed by chain cleaning and the PSG was deposited on the front side, the poly-Si film layer on the front side, the side edges, and the backside boron-diffused area was removed by slot cleaning, and the separation area B-doped silicon layer on the backside was further removed. Then the BSG film layer on the front side was removed by chain cleaning, and the B-diffused layer on the front side was removed by slot cleaning and texturing, and then the PSG film layer and the BSG film layer on the backside were removed by slot cleaning;

[0184] (9) An aluminum oxide film layer with a thickness of 10 nm was deposited on the front side and the backside of the silicon wafer by thermal atomic layer deposition equipment;

[0185] (10) An 80 nm silicon nitride film layer with a refractive index of 2.0-2.05 was deposited on the backside of the cell by plasma-enhanced chemical vapor deposition equipment;

[0186] (11) Depositing 80 nm of silicon oxynitride with a refractive index of 1.95-2.02 on the front side of the cell by plasma enhanced chemical vapor deposition;

[0187] (12) Printing high temperature paste on the back side to prepare the electrode;

[0188] (13) Light injection and laser-assisted sintering.

[0189] The passivation effect of the passivation layer structure of the solar cell of Example 3 and Comparative Example 3 was tested, and the results are shown in Table 5:

[0190] Table 5. Passivation data of the passivation layer structure of the solar cell prepared in Example 3 and Comparative Example 3

[0191]

[0192] In Table 5: iVoc is the ideal open circuit voltage, which represents the passivation of the solar cell, and the larger the value, the better the passivation.

[0193] As can be seen from Table 5: under the same thickness condition (20 nm), the iVoc of the passivation layer structure of the aluminum oxide film layer of Comparative Example 3 can only reach 710 mV, while the passivation film layer structure of the double-sided modified aluminum oxide film layer and the aluminum oxynitride film layer of the present application can achieve 730 mV.

[0194] The performance of the solar cell of Example 3 and Comparative Example 3 was tested, and the results are shown in Table 6:

[0195] Table 6. Performance data of the solar cell prepared in Example 3 and Comparative Example 3

[0196]

[0197] In Table 6: Voc is the open circuit voltage of the solar cell, Isc is the short circuit current of the solar cell, FF is the fill factor of the solar cell, and Eff is the photoelectric conversion efficiency of the solar cell. These four factors represent important electrical performance parameters of the solar cell for light-induced electricity.

[0198] Comparison of the solar cell structures of Example 3 and Comparative Example 3:

[0199] Process level comparison: Compared with the preparation process flow of the TBC solar cell, the preparation process flow of the above-described solar cell structure has fewer plasma-enhanced chemical vapor deposition (450°C process temperature) devices for depositing the tunneling layer and the poly-Si film layer, fewer traditional atomic layer deposition (ALD) (200°C process temperature) devices, fewer plasma-enhanced chemical vapor deposition (500°C process temperature) devices for depositing silicon nitride on the back, and fewer partial wet process devices, a total of four devices. These four devices are replaced by: one passivation film preparation device (can be used for simultaneous front and back film deposition) (maximum 400°C), and one plasma-assisted atomic layer deposition device (100°C). First, the wet process is reduced, which not only saves machine investment cost and chemical consumption, power consumption, but also improves the yield of solar cells. Second, the dust problem caused by improper handling of the plasma-enhanced chemical vapor deposition for preparing the poly-Si film layer is eliminated.

[0200] Comparison of electrical performance parameters: As can be seen from Table 6, the solar cell prepared by the cell structure preparation in the present embodiment has high open-circuit voltage, short-circuit current, and high fill factor, which shows that the passivation properties of the passivation film layer selected in the present application are not weaker than the passivation effect of the passivation tunneling layer structure in the TOPCon solar cell.

[0201] The above-described embodiments only exemplarily illustrate the principles and effects of the present application, and are not intended to limit the present application. Any person skilled in the art can modify or change the above-described embodiments without departing from the spirit and scope of the present application. Therefore, all equivalent modifications or changes made by those skilled in the art without departing from the spirit and technical idea disclosed in the present application should be covered by the claims of the present application.

Claims

1. A method for preparing a passivation layer structure of a solar cell, characterized in that, The method comprises the following steps: Step (1): modifying the surface of the substrate by using one or more of nitrous oxide, ammonia and hydrogen; After the surface of the substrate is modified by the suspended bond chemical activity, an aluminum oxide film layer is deposited on the surface of the substrate, and the aluminum oxide film layer is treated by plasma to obtain a modified aluminum oxide film layer; the treatment of the aluminum oxide film layer by plasma is treating the aluminum oxide film layer by plasma during the deposition of the aluminum oxide film layer; Step (2): depositing an aluminum oxynitride film layer on the surface of the modified aluminum oxide film layer to form a double-layered structure; the refractive index of the aluminum oxynitride film layer ranges from 1.7 to 1.9; Step (3): annealing the double-layered structure in a protective atmosphere to obtain the passivation layer structure of the solar cell.

2. The method of claim 1, wherein: In step (1), the plasma treatment uses one or more of nitrous oxide, ammonia and hydrogen as the plasma precursor gas.

3. The method of claim 1, wherein: In step (3), the annealing temperature is 300-500°C, and the annealing time is 10-30 min.

4. The method of claim 1, wherein: The aluminum oxide film layer is deposited by thermal atomic layer deposition, and the aluminum oxynitride film layer is deposited by plasma-assisted atomic layer deposition or plasma-enhanced chemical vapor deposition; the deposition temperature of the aluminum oxide film layer and the aluminum oxynitride film layer ranges from 120 to 300°C.

5. A passivated layer structure for a solar cell, produced by the production method according to any one of claims 1 to 4, characterized in that The method comprises sequentially depositing a modified aluminum oxide film layer (2) and an aluminum oxynitride film layer (3) on the surface of a substrate (1); the modified aluminum oxide film layer is obtained by treating an aluminum oxide film layer by plasma; the thickness of the modified aluminum oxide film layer ranges from 8 to 15 nm; the refractive index of the aluminum oxynitride film layer ranges from 1.7 to 1.9; and the thickness of the aluminum oxynitride film layer ranges from 2 to 5 nm.

6. Use of the passivation layer structure of the solar cell according to claim 5 in the preparation of a solar cell.

7. A solar cell comprising the passivation layer structure of the solar cell according to claim 5.

8. The solar cell according to claim 7, characterized in that: With the substrate as the reference, the solar cell comprises, from inside to outside, a first diffusion junction (4) having a conductive polarity opposite to that of the substrate, a first locally heavily doped emitter (5) having a conductive polarity opposite to that of the substrate, the passivation layer structure of the solar cell, a first transparent conductive film layer (6) and a first low-temperature electrode (7) on the side of the solar cell facing the light-receiving surface; and the first transparent conductive film layer is in contact with the first locally heavily doped emitter. With the substrate as the reference, the solar cell comprises, from inside to outside, a first locally heavily doped contact region (8) having a conductive polarity same as that of the substrate, the passivation layer structure of the solar cell, a second transparent conductive film layer (9) and a second low-temperature electrode (10) on the side of the solar cell facing the back light-receiving surface; and the second transparent conductive film layer is in contact with the first locally heavily doped contact region.

9. The solar cell according to claim 7, characterized in that: the solar cell is a back contact solar cell; and with the substrate as the reference, the solar cell comprises, from inside to outside, the passivation layer structure of the solar cell and an antireflection layer insulating layer (11) on the side of the solar cell facing the light-receiving surface. The solar cell comprises, from inside to outside, in sequence, a local second diffusion junction (12) with opposite conductive polarity to the substrate, a second local heavily doped emitter (13), a second local heavily doped contact region (14) with the same conductive polarity as the substrate, a passivation layer structure of the solar cell and a third transparent conductive film layer (15) in contact with the second local heavily doped contact region and the second local heavily doped emitter, from the side of the back light to the substrate.

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