A film structure of a solar cell

Abstract

The present invention provides a film structure of a solar cell, belonging to the field of photovoltaic technology. In the film structure of the solar cell provided by the present invention, the first passivation layer for resisting induced potential difference attenuation, the second passivation layer for resisting reflection and meeting the preset transmittance, and the third passivation layer for resisting reflection, meeting the preset transmittance and reducing the metal composite effect at the gate line are sequentially included in the direction away from the N-type emitter on the P-type crystalline silicon substrate. The fourth passivation layer for resisting photothermal induced attenuation and the fifth passivation layer for resisting reflection, meeting the preset transmittance, resisting induced potential difference attenuation and resisting photothermal induced attenuation are sequentially included in the direction away from the N-type emitter on the P-type crystalline silicon substrate. The N-type emitter and the P-type crystalline silicon substrate are connected, thereby satisfying the passivation and anti-reflection requirements of each film structure of the solar cell, and ensuring that the solar cell has anti-PID and anti-LeTID characteristics, effectively improving the component reliability of the battery component, coping with complex practical application environments, and having a wider range of uses.

Description

Technical Field

[0001] The present invention relates to the field of photovoltaic technology, and more specifically, to a film structure of a solar cell. Background Art

[0002] Solar cells are low-cost, high-efficiency renewable energy sources, among which the photoelectric conversion efficiency and component reliability of solar cells are the main parameters that reflect their performance in practical applications. In order to cope with the complex influencing factors in the actual application environment and improve the reliability of solar cell components, higher requirements are also placed on solar cell coating technology.

[0003] Generally speaking, existing solar cell thin films can only meet some of the requirements. For example, when the film structure meets the anti-PID (Potential Induced Degradation) characteristics, it cannot guarantee good passivation of the film layer, and when it guarantees good passivation of the film layer, it cannot meet the anti-PID characteristics or good light absorption effect, or when it meets the hydrogen passivation effect, it cannot guarantee the anti-LeTID (Light and elevated Temperature Induced Degradation) effect, etc. The lack of focus leads to low reliability of solar cell components, which cannot cope with complex actual application environments and have a small scope of use. Summary of the invention

[0004] The invention provides a film structure of a solar cell to solve the problems in the prior art that the solar cell components have low reliability, cannot cope with complex practical application environments, and have a small application range.

[0005] In a first aspect, a film structure of a solar cell is provided, wherein the film structure of the solar cell comprises:

[0006] The directions on the N-type emitter away from the P-type crystalline silicon substrate include:

[0007] A first passivation layer that resists attenuation of induced potential difference, a second passivation layer that resists reflection and meets a preset transmittance, and a third passivation layer that resists reflection, meets a preset transmittance and reduces metal recombination at the gate line;

[0008] The directions on the P-type crystalline silicon substrate away from the N-type emitter include:

[0009] A fourth passivation layer that resists photothermal induced attenuation, and a fifth passivation layer that resists reflection, meets a preset transmittance, resists induced potential difference attenuation, and resists photothermal induced attenuation.

[0010] Optionally, the first passivation layer includes at least two of a silicon nitride layer with a refractive index ≥2.1, an amorphous silicon layer with a refractive index ≥2.1, and a silicon oxide layer with a refractive index ≤1.7.

[0011] Optionally, the second passivation layer includes at least one of a silicon nitride layer having a refractive index of ≥1.9 and ≤2.15 and a silicon oxynitride layer having a refractive index of ≥1.75 and ≤2.0.

[0012] Optionally, the third passivation layer includes at least one of a silicon nitride layer with a refractive index ≥1.9 and ≤2.05, a silicon oxynitride layer with a refractive index ≥1.7 and ≤1.85, and a silicon oxide layer with a refractive index ≥1.6 and less than or equal to 1.75.

[0013] Optionally, the fourth passivation layer includes at least one of a silicon oxide layer with a refractive index ≥1.4 and ≤1.75, a silicon oxynitride layer with a refractive index ≥1.4 and ≤1.75, an amorphous silicon layer with a refractive index ≥1.4 and ≤1.75, a phosphorus-doped silicon nitride layer with a refractive index ≥1.4 and ≤1.75, a nitrogen-doped silicon oxide layer with a refractive index ≥1.4 and ≤1.75, a phosphorus-doped amorphous silicon layer with a refractive index ≥1.4 and ≤1.75, an N-type zinc oxide layer with a refractive index ≥1.4 and ≤1.75, and a titanium oxide layer with a refractive index ≥1.4 and ≤1.75.

[0014] Optionally, the fifth passivation layer includes at least two of a silicon nitride layer having a refractive index ≥1.98 and ≤2.2, a silicon oxynitride layer having a refractive index ≥1.7 and ≤2, and a silicon oxide layer having a refractive index ≥1.6 and ≤1.7.

[0015] Optionally, the preset light transmittance is a light transmittance ≥ 92%.

[0016] Optionally, the thickness of the first passivation layer is ≥10 nanometers and ≤25 nanometers, the thickness of the second passivation layer is ≥25 nanometers and ≤40 nanometers, and the thickness of the third passivation layer is ≥20 nanometers and ≤50 nanometers.

[0017] Optionally, the thickness of the fourth passivation layer is ≥10 nanometers and ≤100 nanometers, and the thickness of the fifth passivation layer is ≥40 nanometers.

[0018] Optionally, each film layer in the film layer structure is prepared by plasma enhanced chemical vapor deposition.

[0019] Compared with the related art, the present invention has the following advantages:

[0020] In an embodiment of the present invention, in the film structure of the solar cell, the direction away from the P-type crystalline silicon substrate on the N-type emitter includes a first passivation layer that resists induced potential difference attenuation, a second passivation layer that resists reflection and meets a preset transmittance, and a third passivation layer that resists reflection, meets a preset transmittance and reduces the metal composite effect at the gate line. The direction away from the N-type emitter on the P-type crystalline silicon substrate includes a fourth passivation layer that resists photothermal induced attenuation, and a fifth passivation layer that resists reflection, meets a preset transmittance, resists induced potential difference attenuation and resists photothermal induced attenuation. The N-type emitter and the P-type crystalline silicon substrate are connected to each other, thereby meeting the passivation and anti-reflection requirements of each film structure of the solar cell while ensuring that the solar cell has anti-PID and anti-LeTID characteristics, effectively improving the component reliability of the battery component, being able to cope with complex actual application environments, and having a wider range of uses.

[0021] The above description is only an overview of the technical solution of the present invention. In order to more clearly understand the technical means of the present invention, it can be implemented according to the contents of the specification. In order to make the above and other purposes, features and advantages of the present invention more obvious and easy to understand, the specific implementation methods of the present invention are listed below. BRIEF DESCRIPTION OF THE DRAWINGS

[0022] Various other advantages and benefits will become apparent to those of ordinary skill in the art by reading the detailed description of the preferred embodiments below. The accompanying drawings are only for the purpose of illustrating the preferred embodiments and are not to be considered as limiting the present invention. Moreover, the same reference symbols are used throughout the accompanying drawings to represent the same components. In the accompanying drawings:

[0023] Figure 1 A schematic diagram of a film structure of a solar cell provided by an embodiment of the present invention;

[0024] Figure 2 A schematic diagram of a specific example of a film structure of a solar cell provided in an embodiment of the present invention. DETAILED DESCRIPTION

[0025] The exemplary embodiments of the present disclosure will be described in more detail below with reference to the accompanying drawings. Although the exemplary embodiments of the present disclosure are shown in the accompanying drawings, it should be understood that the present disclosure can be implemented in various forms and should not be limited by the embodiments set forth herein. On the contrary, these embodiments are provided to enable a more thorough understanding of the present disclosure and to fully convey the scope of the present disclosure to those skilled in the art.

[0026] In the embodiment of the present invention, a solar cell refers to a semiconductor component that can effectively absorb solar energy and convert it into electrical energy, among which crystalline silicon solar cells have a wide range of applications. In solar cells, such as crystalline silicon cells based on thin film passivation PERC (Passivated Emitter and Rear Cell), TOPCon (Tunnel Oxide Passivating Contacts), HJT (Heretojunction) and other film structures directly affect their photoelectric conversion efficiency and component reliability. An embodiment of the present invention provides a film structure of a solar cell, wherein the role and function of the film layer at each position are determined, so that the reliability of the solar cell component is improved while ensuring the photoelectric conversion efficiency of the solar cell through the matching of the functions of different film layers, as shown below:

[0027] Figure 1 A schematic diagram of a film structure of a solar cell provided by an embodiment of the present invention is shown in FIG. Figure 1 As shown, the film structure of the solar cell may include:

[0028] The directions on the N-type emitter 102 away from the P-type crystalline silicon substrate 101 include:

[0029] A first passivation layer 103 that resists attenuation of induced potential difference, a second passivation layer 104 that resists reflection and meets a preset transmittance, and a third passivation layer 105 that resists reflection, meets a preset transmittance and reduces metal recombination at the gate line;

[0030] The directions on the P-type crystalline silicon substrate 101 away from the N-type emitter 102 sequentially include:

[0031] A fourth passivation layer 106 that resists light-heat induced attenuation, and a fifth passivation layer 107 that resists reflection, meets a preset transmittance, resists induced potential difference attenuation, and resists light-heat induced attenuation;

[0032] The N-type emitter 102 is connected to the P-type crystalline silicon substrate 101 .

[0033] In the embodiment of the present invention, the solar cell includes a P-type crystalline silicon substrate 101 and an N-type emitter 102 connected to each other, wherein the P-type crystalline silicon substrate 101 can be single crystal silicon or polycrystalline silicon, and the P-type crystalline silicon substrate 101 can provide support for each layer of thin film and form a PN junction with the N-type emitter 102. Optionally, N-type crystalline silicon can also be used as the substrate. N-type crystalline silicon has a longer minority carrier lifetime, is less sensitive to impurities, and has a weaker photo-induced attenuation effect, and a P-type emitter can be used accordingly. The film layers with specific functions are sequentially arranged on the surfaces of the connected P-type crystalline silicon substrate 101 and the N-type emitter 102, which is the film layer structure of the solar cell provided in the embodiment of the present invention.

[0034] The first passivation layer 103 resists attenuation of the induced potential difference.

[0035] In the embodiment of the present invention, different functional layer structures can be arranged in sequence on the N-type emitter 102 in the direction away from the P-type crystalline silicon substrate 101 according to application requirements, such as a first passivation layer 103 that can resist induced potential difference. The passivation layer can reduce the recombination of carriers on the silicon surface and improve the battery conversion efficiency. Optionally, the first passivation layer 103 can achieve passivation effects of different mechanisms through different structures. For example, the first passivation layer 103 can form chemical bonds with dangling bonds, defect states, defect centers, etc. on the surface of the N-type emitter 102 through chemical elements to achieve chemical passivation, or the first passivation layer 103 can hinder the minority carriers from moving to the silicon surface of the non-metallic contact area through the electric field formed by the fixed charges attached to the film layer, thereby reducing the probability of minority carriers being captured by the recombination center on the silicon surface to achieve field effect passivation. The embodiment of the present invention does not impose specific restrictions on this.

[0036] In the embodiment of the present invention, in the structure of the P-type crystalline silicon substrate 101 and the N-type emitter 102, since the N-type emitter 102 is at a high potential, the majority electron concentration in the P-type crystalline silicon substrate 101 is induced to decrease under the high potential, thereby causing the built-in potential of the battery to decrease, further causing the attenuation of the photoelectric conversion efficiency of the battery. The above phenomenon is usually caused by sodium ions (Na + ) is enriched on the surface, and the positive fixed charges in the anti-reflective film layer form an electric field effect. Optionally, the first passivation layer 103 can achieve anti-induced potential difference attenuation through a selective tunneling film layer to hinder the movement of electrons in the direction of low concentration, or can achieve the effect of anti-induced potential difference attenuation through a film layer with lower fixed charge, such as making the solar cell efficiency decay less than or equal to 5% in a test of anti-induced potential difference attenuation at 60°C, 85% relative humidity, and 96 hours.

[0037] Optionally, the first passivation layer 103 includes at least two of a silicon nitride layer with a refractive index ≥2.1, an amorphous silicon layer with a refractive index ≥2.1, and a silicon oxide layer with a refractive index ≤1.7.

[0038] In an embodiment of the present invention, the first passivation layer 103 is a passivation layer that resists induced potential difference attenuation. Optionally, the first passivation layer 103 includes a structure of more than two film layers. For example, the first passivation layer 103 can be a combination structure of a silicon nitride layer with a refractive index ≥2.1 and an amorphous silicon layer with a refractive index ≥2.1, a combination structure of an amorphous silicon layer with a refractive index ≥2.1 and a silicon oxide layer with a refractive index ≤1.7, a combination structure of a silicon nitride layer with a refractive index ≥2.1 and a silicon oxide layer with a refractive index ≤1.7, or a combination structure of a silicon nitride layer with a refractive index ≥2.1, an amorphous silicon layer with a refractive index ≥2.1, and a silicon oxide layer with a refractive index ≤1.7, etc. Those skilled in the art can select different film layer structures according to the characteristics of the first passivation layer 103, and the embodiment of the present invention does not impose specific restrictions on this.

[0039] Optionally, the thickness of the first passivation layer 103 is ≥10 nanometers and ≤25 nanometers.

[0040] In an embodiment of the present invention, the total thickness of the first passivation layer 103 is 10 nm to 25 nm, that is, the thickness can be any thickness between 10 nm and 25 nm, such as 10 nm, 15 nm, 20 nm, 25 nm, etc. Within the range of thickness ≥ 10 nanometers and ≤ 25 nanometers, the embodiment of the present invention does not impose any specific limitation on the thickness of the first passivation layer 103.

[0041] The second passivation layer 104 is anti-reflective and meets a preset light transmittance.

[0042] In an embodiment of the present invention, on the basis of the first passivation layer 103 on the N-type emitter 102 away from the P-type crystalline silicon substrate 101, a second passivation layer 104 that is anti-reflective and meets a preset transmittance may also be included in sequence, wherein the passivation effect of the second passivation layer 104 may refer to the relevant description of the first passivation layer 103, and will not be repeated here to avoid repetition.

[0043] In the embodiment of the present invention, since silicon has a relatively large refractive index of 3.5 to 6.0 relative to air in the region of 400 nm to 1100 nm from the visible light to the infrared band, it has a large interface reflection loss; in addition, in the process of incident light passing through the dielectric film layer, due to the influence of the material properties of the dielectric film layer, a certain degree of light absorption and reflection will occur, thereby affecting the luminous flux, and further affecting the photoelectric conversion efficiency of the battery. At this time, a second passivation layer 104 with anti-reflection and meeting the preset transmittance is provided on the basis of the first passivation layer 103. Based on the mechanism that when light is incident from a high refractive index medium to a low refractive index medium, total reflection can be achieved within a large refractive index difference and a certain range of incident angles, the second passivation layer 104 can reduce the interface reflection by using a specific refractive index so that the refractive index of each film layer from the N-type emitter 102 to the outside changes from high to low, thereby achieving efficient light absorption in the PN junction, and the transmittance of the film layer decreases with the increase of the refractive index. Therefore, the refractive index of the film layer can be determined according to the transmittance requirement to achieve the effect of improving the luminous flux and anti-reflection.

[0044] Optionally, the preset light transmittance is a light transmittance ≥ 92%.

[0045] In an embodiment of the present invention, the preset transmittance is greater than or equal to 92%. Optionally, the transmittance of the second passivation layer 104 can be any value above 92%, such as 92%, 93%,..., 99%,..., etc., and the embodiment of the present invention does not make any specific limitation on this.

[0046] Optionally, the second passivation layer 104 includes at least one of a silicon nitride layer having a refractive index of ≥1.9 and ≤2.15 and a silicon oxynitride layer having a refractive index of ≥1.75 and ≤2.0.

[0047] In an embodiment of the present invention, the second passivation layer 104 is an anti-reflective passivation layer that meets a preset transmittance. Optionally, the second passivation layer 104 includes a structure of more than one film layer. For example, the second passivation layer 104 may be a silicon nitride layer with a refractive index ≥1.9 and ≤2.15, a silicon oxynitride layer with a refractive index ≥1.75 and ≤2.0, or a combination structure of a silicon nitride layer with a refractive index ≥1.9 and ≤2.15 and a silicon oxynitride layer with a refractive index ≥1.75 and ≤2.0, etc. Those skilled in the art may select different film layer structures according to the characteristics of the second passivation layer 104, and the embodiment of the present invention does not impose any specific restrictions on this.

[0048] Optionally, the thickness of the second passivation layer 104 is ≥25 nanometers and ≤40 nanometers.

[0049] In the embodiment of the present invention, the total thickness of the second passivation layer 104 is 25nm to 40nm, that is, the thickness can be any thickness between 25nm and 40nm, such as 25nm, 30nm, 35nm, 40nm, etc. Within the range of thickness ≥25 nanometers and ≤40 nanometers, the embodiment of the present invention does not impose any specific limitation on the thickness of the second passivation layer 104.

[0050] The third passivation layer 105 is anti-reflective, meets the preset light transmittance and reduces the metal recombination effect at the gate line.

[0051] In the embodiment of the present invention, on the basis of the first passivation layer 103 and the second passivation layer 104 on the N-type emitter 102 away from the P-type crystalline silicon substrate 101, a third passivation layer 105 which is anti-reflective, meets the preset transmittance and reduces the metal composite effect at the gate line can also be included in sequence, wherein the passivation effect of the third passivation layer 105 can refer to the relevant description of the first passivation layer 103, and the anti-reflection effect of the third passivation layer 105 and the effect of meeting the preset transmittance can refer to the relevant description of the second passivation layer 104, and to avoid repetition, they will not be repeated here.

[0052] In the embodiment of the present invention, when adding a gate line, new defect recombination centers will be formed while the metal paste enters the crystalline silicon substrate and crystalline silicon to form an alloy phase, which can easily cause metal recombination, reduce the body life of minority carriers in crystalline silicon, and further affect the photoelectric conversion efficiency of the battery. For example, when silver paste is used on the N emitter 102 side, the silver paste first reacts with the film layer in the direction of the N emitter 102, corrodes through the film layer, and then enters the P-type crystalline silicon substrate 101. Therefore, the third passivation layer 105 can change the chemical properties of the reaction between the metal paste and the third passivation layer 105 by improving the chemical properties of the film layer, thereby reducing the probability of the metal paste forming new defect recombination centers during the doping process, so as to achieve the effect of reducing the metal recombination effect at the gate line.

[0053] Optionally, the third passivation layer 105 includes at least one of a silicon nitride layer with a refractive index ≥1.9 and ≤2.05, a silicon oxynitride layer with a refractive index ≥1.7 and ≤1.85, and a silicon oxide layer with a refractive index ≥1.6 and less than or equal to 1.75.

[0054] In an embodiment of the present invention, the third passivation layer 105 is a passivation layer that is anti-reflective, meets a preset transmittance, and reduces the metal composite effect at the gate line. Optionally, the third passivation layer 105 includes an upper film layer structure, such as the third passivation layer 105 can be a silicon nitride layer with a refractive index ≥1.9 and ≤2.05, can be a silicon oxynitride layer with a refractive index ≥1.7 and ≤1.85, or can be a silicon oxide layer with a refractive index ≥1.6 and less than or equal to 1.75, or can be a combination structure of any two, three, etc. of the above three film layers. Those skilled in the art can select different film layer structures according to the characteristics of the third passivation layer 105, and the embodiment of the present invention does not impose specific restrictions on this.

[0055] Optionally, the thickness of the third passivation layer 105 is ≥20 nanometers and ≤50 nanometers.

[0056] In an embodiment of the present invention, the total thickness of the third passivation layer 105 is 20 nm to 50 nm, that is, the thickness can be any thickness between 20 nm and 50 nm, such as 20 nm, 25 nm, 30 nm, 35 nm, 40 nm, 50 nm, etc. Within the range of thickness ≥ 20 nanometers and ≤ 50 nanometers, the embodiment of the present invention does not impose any specific limitation on the thickness of the third passivation layer 105.

[0057] The fourth passivation layer 106 is resistant to light-heat-induced degradation.

[0058] In the embodiment of the present invention, different functional layer structures may be provided on the P-type crystalline silicon substrate 101 in a direction away from the N-type emitter 102 according to application requirements, such as a fourth passivation layer 106 that resists photothermal induced degradation, wherein the passivation effect of the fourth passivation layer 106 may refer to the relevant description of the first passivation layer 103, and will not be described again here to avoid repetition. In addition, in the embodiment of the present invention, when a field effect passivation film layer with a negative fixed charge or electric field effect is used as the passivation layer on the P-type crystalline silicon substrate 101 side, sodium ions may be accumulated on the surface of the crystalline silicon battery under the action of a high electric potential, and form a strong positive electric field with the dielectric film layer with a positive fixed charge on the other side, thereby weakening the passivation effect of the negative field effect passivation layer on the P-type crystalline silicon substrate 101 side. At this time, those skilled in the art may select the passivation layer structure on the P-type crystalline silicon substrate 101 side according to actual application requirements.

[0059] In the embodiment of the present invention, photothermal induced attenuation is a different attenuation phenomenon exhibited by induced potential difference attenuation at different test temperatures, wherein the test temperature of thermally induced potential difference attenuation is relatively low, generally below 50°C, while photothermal induced attenuation is usually more likely to occur above 50°C. There are more influencing factors involved in photothermal induced attenuation, and the degree of influence is also greater, which is mainly related to the concentration of hydrogen and boron elements. The higher the concentration of hydrogen and boron elements, the more obvious the phenomenon of photothermal induced attenuation. Therefore, the fourth passivation layer 106 can achieve the effect of resisting photothermal induced attenuation by adjusting the content of hydrogen and boron elements in the film layer.

[0060] Optionally, the fourth passivation layer 106 includes at least one of a silicon oxide layer with a refractive index ≥1.4 and ≤1.75, a silicon oxynitride layer with a refractive index ≥1.4 and ≤1.75, an amorphous silicon layer with a refractive index ≥1.4 and ≤1.75, a phosphorus-doped silicon nitride layer with a refractive index ≥1.4 and ≤1.75, a nitrogen-doped silicon oxide layer with a refractive index ≥1.4 and ≤1.75, a phosphorus-doped amorphous silicon layer with a refractive index ≥1.4 and ≤1.75, an N-type zinc oxide layer with a refractive index ≥1.4 and ≤1.75, and a titanium oxide layer with a refractive index ≥1.4 and ≤1.75.

[0061] In the embodiment of the present invention, the fourth passivation layer 106 is a passivation layer that resists light-heat-induced degradation. Optionally, the fourth passivation layer 106 may include more than one film layer structure, such as the fourth passivation layer 106 may be a silicon oxide layer with a refractive index ≥1.4 and ≤1.75, a silicon oxynitride layer with a refractive index ≥1.4 and ≤1.75, an amorphous silicon layer with a refractive index ≥1.4 and ≤1.75, a phosphorus-doped silicon nitride layer with a refractive index ≥1.4 and ≤1.75, or a silicon oxide layer with a refractive index ≥1.4 and ≤1.75. .75, can be a nitride-doped silicon oxide layer with a refractive index ≥1.4 and ≤1.75, can be a phosphorus-doped amorphous silicon layer with a refractive index ≥1.4 and ≤1.75, can be an N-type zinc oxide layer with a refractive index ≥1.4 and ≤1.75, can be a titanium oxide layer with a refractive index ≥1.4 and ≤1.75, or can be a combination structure of any two, three, four,..., eight, etc. of the above eight types of film layers. Those skilled in the art can select different film layer structures according to the characteristics of the fourth passivation layer 106, and the embodiments of the present invention do not impose specific restrictions on this.

[0062] Optionally, the thickness of the fourth passivation layer 106 is ≥10 nanometers and ≤100 nanometers.

[0063] In the embodiment of the present invention, the total thickness of the fourth passivation layer 106 is 10nm to 100nm, that is, the thickness can be any thickness between 10nm and 100nm, such as 10nm, 15nm, 20nm, 30nm, 50nm, 80nm, 90nm, 100nm, etc. Within the range of thickness ≥10 nanometers and ≤100 nanometers, the embodiment of the present invention does not specifically limit the thickness of the fourth passivation layer 106.

[0064] The fifth passivation layer 107 is anti-reflective, meets a preset transmittance, resists induced potential difference attenuation, and resists photothermal induced attenuation.

[0065] In the embodiment of the present invention, on the basis of including the fourth passivation layer 106 on the P-type crystalline silicon substrate 101 away from the N-type emitter 102, a fifth passivation layer 107 is also included in sequence, which is anti-reflective, meets the preset transmittance, resists induced potential difference attenuation and resists photothermal induced attenuation, wherein anti-reflection and meeting the preset transmittance can correspond to the relevant description of the second passivation layer 104, resistance to induced potential difference attenuation can correspond to the relevant description of the first passivation layer 101, and resistance to photothermal induced attenuation can correspond to the relevant description of the fourth passivation layer 106. To avoid repetition, they will not be repeated here.

[0066] Optionally, the fifth passivation layer 107 includes at least two of a silicon nitride layer having a refractive index of ≥1.98 and ≤2.2, a silicon oxynitride layer having a refractive index of ≥1.7 and ≤2, and a silicon oxide layer having a refractive index of ≥1.6 and ≤1.7.

[0067] In the embodiment of the present invention, the fifth passivation layer 107 is a passivation layer that is anti-reflective, meets a preset transmittance, resists induced potential difference attenuation, and resists photothermal induced attenuation. Optionally, the fifth passivation layer 107 may include a structure of more than two film layers, such as the fifth passivation layer 107 may be a combination structure of a silicon nitride layer with a refractive index ≥1.98 and ≤2.2 and a silicon oxynitride layer with a refractive index ≥1.7 and ≤2, or a silicon oxynitride layer with a refractive index ≥1.7 and ≤2 and a silicon oxynitride layer with a refractive index ≥1.6 and ≤1.7. The combination structure of the silicon layer may also be a combination structure of a silicon nitride layer with a refractive index ≥1.98 and ≤2.2 and a silicon oxide layer with a refractive index ≥1.6 and ≤1.7, or a combination structure of a silicon nitride layer with a refractive index ≥1.98 and ≤2.2, a silicon oxynitride layer with a refractive index ≥1.7 and ≤2, and a silicon oxide layer with a refractive index ≥1.6 and ≤1.7, etc. Those skilled in the art may select different film layer structures according to the characteristics of the fifth passivation layer 107, and the embodiment of the present invention does not impose any specific restrictions on this.

[0068] Optionally, the thickness of the fifth passivation layer 107 is ≥40 nanometers.

[0069] In the embodiment of the present invention, the total thickness of the fifth passivation layer 107 is ≥40nm, that is, the thickness can be any thickness ≥40 nanometers, such as 40nm, 45nm, 50nm, 60nm, etc. The embodiment of the present invention does not specifically limit the thickness of the first passivation layer 103.

[0070] In an embodiment of the present invention, in the film structure of the solar cell, the direction away from the P-type crystalline silicon substrate on the N-type emitter includes a first passivation layer that resists induced potential difference attenuation, a second passivation layer that resists reflection and meets a preset transmittance, and a third passivation layer that resists reflection, meets a preset transmittance and reduces the metal composite effect at the gate line. The direction away from the N-type emitter on the P-type crystalline silicon substrate includes a fourth passivation layer that resists photothermal induced attenuation, and a fifth passivation layer that resists reflection, meets a preset transmittance, resists induced potential difference attenuation and resists photothermal induced attenuation. The N-type emitter and the P-type crystalline silicon substrate are connected to each other, thereby meeting the passivation and anti-reflection requirements of each film structure of the solar cell while ensuring that the solar cell has anti-PID and anti-LeTID characteristics, effectively improving the component reliability of the battery component, being able to cope with complex actual application environments, and having a wider range of uses.

[0071] Optionally, each film layer in the film layer structure is prepared by plasma enhanced chemical vapor deposition.

[0072] In the embodiment of the present invention, each film layer in the film layer structure can be prepared by plasma enhanced chemical vapor deposition, that is, each film layer is deposited by ionizing a gas containing atoms of the film layer components to form a plasma. Optionally, different gases can be selected according to the materials of different film layers, and process parameters such as temperature, pressure, and gas flow rate can be adjusted. The deposition equipment can select a tubular furnace, a flat furnace, etc., or the deposition equipment can select a microwave type, a direct current type, etc., and the embodiment of the present invention does not impose specific restrictions on this.

[0073] In the embodiment of the present invention, different film layers in the related technology, especially different functional film layers, are prepared by using a variety of equipment and methods. For example, the passivation layer on the P-type silicon side prepared by the related technology is an aluminum oxide layer prepared by an ALD (Atomic layer deposition) device, while the anti-reflection layer is prepared by a PECVD device. The two film layers are prepared by different equipment, resulting in the need to switch between devices during film layer preparation, which leads to high preparation costs and low production capacity. In the film layer structure of the solar cell in the embodiment of the present invention, each film layer is prepared by plasma enhanced chemical vapor deposition, so that a single device is used to complete the preparation of different functional film layers. While meeting the requirements of solar cell passivation, anti-reflection, and component reliability, the film forming equipment is single, the cost is low, and the production capacity is improved.

[0074] Figure 2 A schematic diagram of a specific example of a film structure of a solar cell provided by an embodiment of the present invention, such as Figure 2 As shown, in a specific example, the film layer structure is deposited on a solar cell using a JEC tube PECVD machine, and the film layer structure of the solar cell includes:

[0075] The directions on the N-type emitter 202 away from the P-type crystalline silicon substrate 201 include:

[0076] A first passivation layer 203 that resists attenuation of induced potential difference, a second passivation layer 204 that resists reflection and meets a preset transmittance, and a third passivation layer 205 that resists reflection, meets a preset transmittance and reduces metal recombination at the gate line;

[0077] The directions on the P-type crystalline silicon substrate 201 away from the N-type emitter 202 include:

[0078] A fourth passivation layer 206 that resists light-heat induced attenuation, and a fifth passivation layer 207 that resists reflection, meets a preset transmittance, resists induced potential difference attenuation, and resists light-heat induced attenuation;

[0079] The N-type emitter 202 is connected to the P-type crystalline silicon substrate 201 .

[0080] The direction in which the first passivation layer 203 is away from the P-type crystalline silicon substrate 201 includes:

[0081] A combined structure of a silicon oxide layer 2031 having a thickness of 1 nm to 3 nm prepared by oxygen plasma oxidation, and a silicon nitride layer 2032 having a refractive index of 2.3 and a thickness of 9 nm to 11 nm;

[0082] The second passivation layer 204 is a silicon nitride layer with a refractive index of 2.0 and a thickness of 30 nm;

[0083] The third passivation layer 205 is a silicon oxynitride layer with a refractive index of 1.7 and a thickness of 35 nm;

[0084] The fourth passivation layer 206 includes the following in the direction away from the N-type emitter 202:

[0085] A silicon oxide layer 2061 with a thickness of 1 nm to 3 nm prepared by oxygen plasma oxidation, and a silicon oxide layer 2062 with a refractive index of 1.7 and a thickness of 50 nm;

[0086] The fifth passivation layer 207 includes the following in the direction away from the N-type emitter 202:

[0087] A silicon nitride layer 2071 having a refractive index of 2.15 and a thickness of 35 nm, a silicon nitride layer 2072 having a refractive index of 2.0 and a thickness of 60 nm, and a silicon nitride oxide 2073 having a refractive index of 1.72 and a thickness of 50 nm.

[0088] Each film layer in the film layer structure of the above solar cell is deposited by using a 448-piece tube-type PECVD device, wherein the deposition process parameters of each film layer are shown in Table 1 below:

[0089] Table 1 Film structure deposition process parameters

[0090] Temperature / ℃ Pressure / mTorr Power / W 450～510 7500～8500 8000～14500

[0091] Furthermore, the gas flow rate of each film layer gas source can be set within the range of 700 to 8000 sccm according to different gas types.

[0092] In the process, the first to third passivation layers 203 to 205 are first deposited on the N-type emitter 202 side, and then the fourth to fifth passivation layers 206 to 207 are deposited on the P-type crystalline silicon substrate side.

[0093] Those skilled in the art will readily appreciate other embodiments of the present invention after considering the specification and practicing the invention disclosed herein. This application is intended to cover any variations, uses or adaptations of the present invention that follow the general principles of the present invention and include common knowledge or customary techniques in the art that are not disclosed by the present invention. The specification and examples are to be considered exemplary only, and the true scope and spirit of the present invention are indicated by the claims.

[0094] It should be understood that the present invention is not limited to the exact construction that has been described above and shown in the drawings and that various modifications and changes may be made without departing from the scope thereof. The scope of the present invention is limited only by the appended claims.

Claims

1. A film structure of a solar cell, characterized in that: The film structure of the solar cell comprises: The directions on the N-type emitter away from the P-type crystalline silicon substrate include: A first passivation layer that resists attenuation of induced potential difference, a second passivation layer that resists reflection and meets a preset transmittance, and a third passivation layer that resists reflection, meets a preset transmittance and reduces metal recombination at the gate line; The directions on the P-type crystalline silicon substrate away from the N-type emitter include: A fourth passivation layer that resists photothermal induced attenuation, and a fifth passivation layer that resists reflection, meets a preset transmittance, resists induced potential difference attenuation, and resists photothermal induced attenuation; The N-type emitter is connected to the P-type crystalline silicon substrate; the preset light transmittance is ≥92%; Wherein, the first passivation layer comprises at least two of a silicon nitride layer with a refractive index ≥ 2.1, an amorphous silicon layer with a refractive index ≥ 2.1, and a silicon oxide layer with a refractive index ≤ 1.7; The second passivation layer includes at least one of a silicon nitride layer having a refractive index of ≥1.9 and ≤2.15 and a silicon oxynitride layer having a refractive index of ≥1.75 and ≤2.0; The third passivation layer includes at least one of a silicon nitride layer having a refractive index of ≥1.9 and ≤2.05, a silicon oxynitride layer having a refractive index of ≥1.7 and ≤1.85, and a silicon oxide layer having a refractive index of ≥1.6 and ≤1.75; The thickness of the first passivation layer is ≥10 nanometers and ≤25 nanometers, the thickness of the second passivation layer is ≥25 nanometers and ≤40 nanometers, and the thickness of the third passivation layer is ≥20 nanometers and ≤50 nanometers.

2. The film structure of the solar cell according to claim 1, characterized in that: The fourth passivation layer includes at least one of a silicon oxide layer with a refractive index ≥1.4 and ≤1.75, a silicon oxynitride layer with a refractive index ≥1.4 and ≤1.75, an amorphous silicon layer with a refractive index ≥1.4 and ≤1.75, a phosphorus-doped silicon nitride layer with a refractive index ≥1.4 and ≤1.75, a nitrogen-doped silicon oxide layer with a refractive index ≥1.4 and ≤1.75, a phosphorus-doped amorphous silicon layer with a refractive index ≥1.4 and ≤1.75, an N-type zinc oxide layer with a refractive index ≥1.4 and ≤1.75, and a titanium oxide layer with a refractive index ≥1.4 and ≤1.

75.

3. The film structure of the solar cell according to claim 1, characterized in that: The fifth passivation layer includes at least two of a silicon nitride layer having a refractive index of ≥1.98 and ≤2.2, a silicon oxynitride layer having a refractive index of ≥1.7 and ≤2, and a silicon oxide layer having a refractive index of ≥1.6 and ≤1.

7.

4. The film structure of the solar cell according to claim 1, characterized in that: The thickness of the fourth passivation layer is ≥10 nanometers and ≤100 nanometers, and the thickness of the fifth passivation layer is ≥40 nanometers.

5. The film structure of the solar cell according to claim 1, characterized in that: Each film layer in the film layer structure is prepared by plasma enhanced chemical vapor deposition.

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