Anti-reflection coating for solar cells, and design method, manufacturing method, and design program for solar cells equipped with anti-reflection coating

Abstract

To provide a design method for an antireflection film for a solar battery capable of improving antireflection performance in indoor use.SOLUTION: A design method for a solar battery antireflection film includes: calculating an energy density distribution g(θ) of a solar battery having an antireflection film with respect to an incident angle θ of isotropic diffused light with respect to a surface of the antireflection film based on Formula (1): [Mathematical formula 1] (in the formula, θ is an angle of incidence of the isotropic diffused light relative to the surface of the solar battery and g (θ) is light energy density); and determining a configuration of the antireflection film that maximizes power generation efficiency of the solar battery based on the calculated energy density distribution g (θ).SELECTED DRAWING: Figure 4

Description

[Technical Field]

[0001] The present invention relates to an anti-reflection coating for a solar cell, and a design method, a manufacturing method, and a design program for a solar cell equipped with an anti-reflection coating. [Background technology]

[0002] To improve the power generation efficiency of solar cells, anti-reflective multilayer coatings that suppress light reflection on the cell surface are widely used. Figure 1 shows a cross-sectional view of the structure and function of the anti-reflective coating on a solar cell. If a solar cell does not have an anti-reflective coating, as shown in Figure 1(A), incident light is reflected and the light energy escapes. However, if the solar cell has an anti-reflective coating on its surface, as shown in Figure 1(B), the reflected light is suppressed, allowing the solar cell to efficiently absorb light and generate electricity.

[0003] In general, when designing an anti-reflection film, the characteristics of each layer of the anti-reflection film, such as the film thickness, are determined so that the amount of power generated is maximized when light is perpendicularly incident on the solar cell surface. This design method aims to install the solar cell panel so that midday sunlight, when the light intensity is strongest, strikes it perpendicularly, and to make the most effective use of the light energy under these conditions (Non-Patent Document 1, Non-Patent Document 2). [Prior art documents] [Non-patent literature]

[0004] [Non-Patent Document 1] Mitsunobu Kohiyama, Optical Thin Film Filter Design, Optronics Co., Ltd. (2006). [Non-patent document 2] H. Angus Macleod, “Thin-film optical filters,” 4th ed., CRC Press, Boca Raton (2010). Summary of the Invention [Problem to be solved by the invention]

[0005] In contrast, the inventors discovered that when solar cells are used to generate electricity indoors, such as in factories or homes, as in IoT devices (various types of sensor equipment connected to the Internet), which have become increasingly popular in recent years, the direction of light relative to the solar cell changes depending on the position of the lighting and the orientation of the solar cell, and therefore it is not appropriate to design an anti-reflective film that assumes a specific direction of light.Furthermore, the indoor environment mainly consists of diffused light caused by multiple reflections on the walls and ceiling, and therefore it is necessary to take into account the optical conditions in which light is incident from all directions simultaneously.

[0006] Therefore, there is a demand for a method for designing an anti-reflection coating for solar cells that can improve the anti-reflection performance when used indoors compared to conventional methods. [Means for solving the problem]

[0007] The gist of the present invention is as follows. (1) (A) The energy density distribution g(θ) of a solar cell having an anti-reflection coating with respect to the incident angle θ of isotropically diffused light on the surface of the anti-reflection coating is calculated using the formula (1):

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[0008] According to the present invention, it is possible to provide a method for designing an anti-reflection film for a solar cell that can improve the anti-reflection performance when used indoors. [Brief explanation of the drawings]

[0009] [Figure 1] FIG. 1 is a cross-sectional view showing the structure and function of an anti-reflection film of a solar cell. [Figure 2] FIG. 2 is a schematic diagram of isotropically diffused light on a solar cell in an indoor environment. [Figure 3] FIG. 3 is a schematic diagram showing spherical coordinates (θ, φ). [Figure 4] FIG. 4 is a graph of the light energy density g(θ) received by a solar cell due to isotropically diffused light with an incident angle θ. [Figure 5] Figure 5 shows an optimization algorithm that shows the procedure for optimally designing an anti-reflection coating. [Figure 6] Figure 6 is a schematic diagram of an example of an eight-layer anti-reflection coating designed using SiO2 and TiO2 layers for an organic thin-film solar cell. [Figure 7] Figure 7 is a schematic diagram of an example of a four-layer anti-reflection coating designed using materials with adjusted refractive indexes for organic thin-film solar cells. DETAILED DESCRIPTION OF THE INVENTION

[0010] The present disclosure provides (A) an energy density distribution g(θ) of a solar cell having an anti-reflection coating with respect to an incident angle θ of isotropically diffused light on a surface of the anti-reflection coating, calculated using the formula (1):

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[0011] According to the design method of the present disclosure (hereinafter also referred to as the present design method), it is possible to provide an antireflection coating for solar cells that can substantially maximize the power generation efficiency of solar cells when used indoors, essentially taking into account the indoor optical environment, which is completely different from that outdoors, i.e., an antireflection coating for solar cells that has improved antireflection performance compared to conventional coatings. The solar cells to which the antireflection coating provided by the present design method is applied are not particularly limited, and may be, for example, organic thin-film solar cells, silicon solar cells, perovskite solar cells, etc.

[0012] Furthermore, this design method can significantly improve efficiency during indoor use while maintaining efficiency during outdoor use. Furthermore, because this design method is based on the design principle of increasing the average power generation (expected power generation) under optical conditions where light is received from various directions, it can be applied not only to indoor environments but also to the design of anti-reflection coatings for solar cells mounted on various mobile systems (electric vehicles, solar planes, etc.) where light is received from all directions and the direction of the light is unpredictable.

[0013] Furthermore, when manufacturing an anti-reflection coating with a multilayer structure obtained using this design method, adjusting the thickness and refractive index of each layer to a certain extent can achieve a sufficient improvement in power generation efficiency compared to conventional methods, and adjusting the thickness and refractive index of each layer basically does not require changes to the equipment, such as the sputtering equipment, used to deposit each layer, so there is almost no increase in the cost of the solar cell.This design method makes it possible to significantly improve the power generation efficiency, preferably by about 1.1 to 1.6%, when applied to various indoor devices (such as IoT devices) and mobile systems, while maintaining the cost of the solar cell at approximately the same level as conventional methods.

[0014] Conventionally, when using solar cells in an indoor environment, the direction of incident light varies depending on the relative position of the light source (lighting and windows) and the orientation of the solar cell surface, making it very difficult to predict the direction of light when designing an anti-reflection coating.

[0015] This is especially true when designing anti-reflective coatings for solar cells used in mobile IoT devices such as active RFID tags, or when the same solar cell is used across multiple devices (e.g., different types of sensors). Furthermore, in indoor environments, scattered light occurs when light repeatedly bounces off various objects, floors, walls, etc., and scattered light coming from all directions typically accounts for a significant fraction of the incident light energy.

[0016] For this reason, when designing anti-reflection coatings for indoor optical environments, the assumption of isotropic diffuse light, in which a solar cell receives light from various directions randomly and with equal probability, is generally appropriate. Figure 2 shows a schematic diagram of isotropic diffuse light on a solar cell in an indoor environment. In Figure 2, light coming from a direction perpendicular to the solar cell surface has an incident angle θ = 0°.

[0017] The process of deriving equation (1) that expresses the energy density distribution g(θ) with respect to the incident angle θ of isotropically diffused light on the surface of an anti-reflection coating will be described below.

[0018] In an optical environment where a solar cell receives isotropically diffused light, the light energy (irradiance) dE irradiated onto the surface of the solar cell by a ray of light contained in a solid angle dΩ at an incident angle θ is expressed by the formula (A.1) based on the basic theory of electromagnetic waves:

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[0019] Here, to calculate the distribution of light energy received by a solar cell with respect to the angle of incidence, we introduce the spherical coordinates (θ, φ) shown in Figure 3. The solid angle dΩ, the angle of incidence θ, and the azimuthal angle φ are expressed by Equation (A.2):

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[0020] g(θ) is given by equation (A.4):

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[0021] By using this constraint, F S Since (λ) = πL(λ), by substituting this relationship into equation (A.3) again, we obtain equation (1):

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[0022] That is, assuming isotropic diffused light, the light energy density distribution g(θ) (probability distribution of light energy with respect to the incident angle θ) actually received by the solar cell with respect to the incident angle θ is expressed by equation (1).

[0023] Figure 4 shows a graph of g(θ) versus the incident angle θ. Figure 4 shows the light energy density g(θ) actually received by a solar cell with isotropically diffused light. As can be seen from the function shape of g(θ) in Figure 4, under isotropically diffused light conditions, a solar cell receives the strongest light energy at an incident angle of θ = 45°, and receives almost no light energy at angles around θ = 0° and 90°. This means that the conventional method of designing an anti-reflection coating to increase power generation efficiency at normal incidence (θ = 0°) is not appropriate for indoor use.

[0024] According to this design method, an anti-reflection coating for a solar cell can be designed to maximize power generation efficiency when the solar cell is exposed to isotropic diffuse light in an indoor environment or an equivalent environment.

[0025] Preferably, determining a configuration of the anti-reflection film that maximizes the power generation efficiency of the solar cell based on the calculated energy density distribution g(θ) includes: (B) determining an nth configuration of the antireflection film; (C) The power generation amount J of the solar cell with respect to the incident angle θ based on the nth configuration of the antireflection film. SC (θ), or the reflectance R(λ, θ) of the entire solar cell having the anti-reflection coating at the incident angle θ and wavelength λ; (D) The calculated energy density distribution g(θ) and the calculated J SC (θ) or the calculated relationship with R(λ,θ), the average value J of the power generation amount of the solar cell is calculated. SC、ave or the average reflectance R of the solar cell ave Calculating the (E) The J calculated using an optimization engine SC、ave maximizes or R ave determining an (n+1)th configuration of the anti-reflection coating that minimizes Including, The n is a natural number starting from 1, The J calculated using the optimization engine SC、ave or the above R ave The method includes repeating steps (C) to (E) above until the change in the reflection coefficient converges within a predetermined range, and determining a final configuration of the antireflection film.

[0026] Fig. 5 shows an algorithm for determining the configuration of the antireflection coating, including the above (B) to (E). The algorithm shown in Fig. 5 is an optimization algorithm for optimizing the configuration of the antireflection coating, and corresponds to steps α-1 to α-5 or steps β-2 to β-5 described below.

[0027] Step α-1 The initial values ​​(initial configuration) of the antireflection film are determined. Step α-1 corresponds to (B) above when n=1. The configuration of the antireflection film may include the number of layers constituting the antireflection film, the thickness of each layer, the wavelength dependence of the refractive index of each layer, etc. The nth configuration of the antireflection film is preferably the number of layers of the antireflection film, the thickness of each layer, the refractive index of each layer, or a combination thereof. The initial values ​​(initial configuration) of the antireflection film may be determined by any method, such as by making it the same as a commonly used known configuration or by determining it based on a known configuration. A commonly used known configuration of an antireflection film is, for example, a multilayer film containing SiO2, which has a low refractive index, and TiO2, which has a high refractive index. The refractive index of each layer constituting the antireflection film, such as SiO2 or TiO2, is expressed as a function of the wavelength of the incident light obtained by optical measurement.

[0028] A multilayer film containing SiO2, which has a low refractive index, and TiO2, which has a high refractive index, is preferred because it has a wide design range. The number of layers in the multilayer film is not particularly limited, but may be, for example, 2 to 10 layers or 4 to 8 layers. The initial value (initial configuration) of the anti-reflection film is preferably determined randomly as described in step β-1 below.

[0029] Step α-2 Solar cell power generation current J for incident angle θ SC (θ) (for case 1), or the relationship of reflectivity to wavelength λ and incident angle θ, R(λ,θ) (for case 2), is calculated by optical analysis using numerical calculations to examine light propagation. Step α-2 corresponds to (C) above.

[0030] Step α-3 The value of the evaluation function I is calculated using formulas (1) to (4) (for case 1), or formulas (1), (2), (5), and (6) (for case 2). Step α-3 corresponds to (D) above.

[0031] Step α-4 Using the optimization engine, the configuration of the anti-reflection coating (such as the film thickness and refractive index of each layer) to be calculated next is determined in order to increase the evaluation function I. The optimization engine can be any engine, such as a gradient method, a quasi-Newton method, or a simulated annealing method. Step α-4 corresponds to (E) above.

[0032] Step α-5 If the convergence condition of the solution is met, the search for the optimal solution ends. The convergence condition can be determined arbitrarily. If it is not met, return to step α-2 and repeat steps α-2 to α-4 until the convergence condition is met.

[0033] Preferably, an optimization method (multi-start method) that repeats a search from a large number of randomly selected initial values ​​can be applied. The multi-start method can further improve performance without depending on the initial values ​​used in the optimization calculation. The algorithm for optimal design using the multi-start method is described by the following steps β-1 to β-6.

[0034] Step β-1 The initial values ​​(initial configuration) of the anti-reflection film configuration (thickness of each layer, refractive index, etc.) are determined randomly within the design range. Step β-1 corresponds to (B) above when n=1.

[0035] Step β-2 Relationship between incident angle θ and generated current J SC (θ) (in the case of Case 1), or the relationship of reflectance with respect to the incident angle θ and wavelength λ, R(λ,θ) (in the case of Case 2), is calculated by optical analysis. Step β-2 corresponds to (C) above.

[0036] Step β-3 The evaluation function I is calculated using formulas (1) to (4) (for case 1), or formulas (1), (2), (5), and (6) (for case 2). Step β-3 corresponds to (D) above.

[0037] Step β-4 Using the optimization engine, the configuration of the anti-reflection coating (such as the film thickness and refractive index of each layer) to be calculated next is determined in order to increase the evaluation function I. The optimization engine can be any engine, such as a gradient method, a quasi-Newton method, or a simulated annealing method. Step β-4 corresponds to (E) above.

[0038] Step β-5 If the convergence condition of the solution is met, save the obtained solution and proceed to step β-6. The convergence condition can be determined arbitrarily. If the convergence condition of the solution is not met, return to step β-2.

[0039] Step β-6 If the number of solutions saved in step β-5 is equal to or greater than a predetermined number, the solution with the largest evaluation function I among all the saved solutions is determined as the optimal solution, and the process ends. On the other hand, if the number of solutions saved in step β-5 has not yet reached the predetermined number, the process returns to step β-1. The predetermined number of solutions saved in step β-5 is not particularly limited, but may be, for example, 100 to 1000. In other words, the number of initial values ​​(initial configurations) of the anti-reflection coating randomly determined in step β-1 may be, for example, 100 to 1000.

[0040] Maximizing the power generation efficiency when a solar cell receives isotropically diffused light preferably means maximizing the evaluation function I expressed by the following formula (2). The structure of the multilayer film of the antireflection coating can be determined so as to maximize the evaluation function I. The evaluation function I in formula (2) is related to the average value (expected value) of the amount of power generated by the solar cell. In this specification, the average value means the expected value, which is a weighted average obtained by assigning probability weights to all values ​​of random variables, and hereinafter will also be referred to simply as the average value.

[0041]

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[0042] (Case 1) Short-circuit current density (generated current) J under isotropic diffuse light conditions SC Maximizing If the optical characteristics of the solar cell (such as the thickness of each layer, the refractive index, and the wavelength dependence of the absorption characteristics) can be understood, the average power generation current (expected value of the power generation current) J of the solar cell can be calculated. SC、ave An anti-reflection coating suitable for indoor use can be designed so as to maximize H(θ), which is referred to as Case 1. The optical characteristics of a solar cell can be understood, for example, by experimental measurements or by using a solar cell whose characteristics have been understood. In Case 1, H(θ) is expressed by the following equation (3).

[0043]

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[0044] In Case 1, the evaluation function I in Equation (2) is the J due to isotropic diffuse light. SC The average value of J SC、ave matches J SC、ave is given by equation (4):

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[0045] In this way, the design method for Case 1 is to minimize the short-circuit current density J due to isotropic diffused light. SC The average value of J SC、ave The goal is to maximize the average power generation (expected power generation) of indoor solar cells that receive light from various directions.

[0046] (Case 2) Minimizing reflectance under isotropic diffuse light conditions When it is difficult to accurately measure the optical properties of each layer that makes up a solar cell device, it is possible to design an anti-reflection coating suitable for indoor use using the reflectance properties of the entire solar cell device equipped with an anti-reflection coating; this case is called Case 2. The reflectance properties of the entire device refer to the reflectance when light is incident on the device surface. In Case 2, H(θ) is expressed by the following equation (5).

[0047]

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[0048] In Case 2, the evaluation function I in Equation (2) is the average value of reflectance under isotropic diffuse light conditions, R ave The negative value of (-R ave ) and R aveis expressed by the following formula (6): Formula (6) can be obtained by substituting formula (5) into formula (2).

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[0049] Thus, the design method for Case 2 is -R ave By maximizing the value of R ave The objective is to minimize the reflectance of the solar cell, which means minimizing the average reflectance of the solar cell for indoor use.

[0050] Thus, the design objectives for Case 1 and Case 2 are to maximize the average power generation (expected value of power generation) and minimize the average reflectance (expected value of reflectance), respectively, and in both cases, the objective is to maximize the average value of power generation efficiency expected under conditions of isotropic diffuse light. When designing an antireflection coating, the selection between Case 1 and Case 2 may be made arbitrarily, or may be made based on information on the optical properties of the solar cell that is available when designing the antireflection coating.

[0051] That is, when it is difficult to accurately grasp or measure the optical properties of each layer that makes up a solar cell device (such as the thickness of each layer, the refractive index, and the wavelength dependence of the absorption properties), it is possible to design an anti-reflection coating suitable for indoor use using the method in Case 2, using the reflectance properties of the entire device, which is relatively easy to obtain.On the other hand, when the detailed optical properties of the solar cell can be grasped or measured through experiments, etc., it is possible to design an anti-reflection coating with higher performance by calculating the average power generation current (expected value of power generation current) using the method in Case 1.

[0052] The present disclosure also relates to a method for manufacturing an anti-reflection coating for a solar cell, including the above-described method for designing an anti-reflection coating for a solar cell. As described above, this design method allows an anti-reflection coating for a solar cell to be manufactured using conventional manufacturing processes. Therefore, this manufacturing method allows an anti-reflection coating that enables solar cells to be obtained with higher power generation efficiency than conventional ones to be manufactured at a cost equivalent to that of conventional ones.

[0053] The present disclosure also relates to a method for manufacturing a solar cell equipped with an anti-reflection coating, including the above-described method for designing an anti-reflection coating for a solar cell. As described above, this design method allows the anti-reflection coating for a solar cell to be manufactured using conventional manufacturing processes, and the solar cell body can be manufactured using the same method as conventional methods. Therefore, this manufacturing method allows solar cells equipped with an anti-reflection coating that has better power generation efficiency than conventional methods to be manufactured at the same cost as conventional methods.

[0054] The present disclosure also provides a method for calculating, on a computer, (A) an energy density distribution g(θ) of a solar cell having an anti-reflection coating with respect to an incident angle θ of isotropically diffused light on a surface of the anti-reflection coating, using the formula (1):

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[0055] Preferably, the configuration determination process for determining the configuration of the anti-reflection film that maximizes the power generation efficiency of the solar cell based on the calculated energy density distribution g(θ) includes: (B) an n-th configuration determination process for determining an n-th configuration of the anti-reflection film; and (C) a power generation amount J of the solar cell with respect to the incident angle θ based on the n-th configuration of the anti-reflection film. SC (θ), or J, which calculates the reflectance R(λ, θ) of the entire solar cell having the anti-reflection coating for the incident angle θ and wavelength λ. SC (θ) or reflectivity R(λ, θ), (D) the calculated energy density distribution g(θ) and the calculated J SC (θ) or the calculated relationship with R(λ,θ), the average value J of the power generation amount of the solar cell is calculated. SC、aveor the average reflectance R of the solar cell ave Calculate R ave (E) the J calculated using an optimization engine; SC、ave maximizes or R ave a n+1-th configuration determination process for determining an n+1-th configuration of the anti-reflection coating that minimizes J, where n is a natural number starting from 1, and SC、ave or the above R ave The method includes repeating steps (C) to (E) above until the change in the reflection coefficient converges within a predetermined range, and determining a final configuration of the antireflection film.

[0056] determining a first configuration of the antireflection film when n is 1, maximizing the power generation efficiency of the solar cell; SC (θ), J SC、ave , R(λ,θ), R ave , H(θ), the evaluation function I, the n-th configuration of the antireflection film, and the like can be applied to the configuration related to the above design method.

[0057] The computer that executes this program may include a communication unit, a memory unit, and a processing unit, and may be a mobile terminal or information terminal such as a smartphone, tablet, or personal computer, or a server.

[0058] The communication unit may be implemented as hardware, firmware, communication software such as a TCP / IP driver or a PPP driver, or a combination of these. The communication unit may be a wireless communication unit or a wired communication unit. The communication unit may receive data by serial communication using a USB cable. The communication unit may have an interface circuit for performing short-range wireless communication according to a communication method such as Bluetooth (registered trademark). The communication unit may have a receiving circuit for receiving various signals by infrared communication or the like. The communication unit may also have a communication interface circuit for a wired LAN.

[0059] The storage unit is, for example, a semiconductor memory device such as a ROM or RAM. The storage unit may also be, for example, a magnetic disk, an optical disk, or any other storage device capable of storing data. The storage unit stores an operating system program, a driver program, an application program, data, the program, and the like used for processing in the processing unit. Computer programs including the program stored in the storage unit may be installed into the storage unit from a computer-readable portable recording medium such as a CD-ROM or DVD-ROM using a known setup program, or may be installed into the storage unit via a network.

[0060] The processing unit has one or more processors and their peripheral circuits. The processing unit controls the overall operation of the server, and is, for example, a CPU (Central Processing Unit). The processing unit can control the operation of the communication unit and the storage unit.

[0061] The processing unit executes various processes based on programs stored in the storage unit (driver programs, operating system programs, application programs, this program, etc.) The processing unit can also execute multiple programs (application programs, etc.) in parallel. [Example]

[0062] (Example 1, Comparative Example 1) To verify the effectiveness of the present invention, an optical design of an anti-reflection coating was performed using an organic thin-film solar cell, which has recently attracted attention as an indoor power generation device. The design involved using the characteristic matrix method, a typical electromagnetic field analysis method, and the algorithm was written in a C language program. The anti-reflection coating for the same solar cell device was designed and analyzed using both this design method (a: Example 1) and a conventional method (b: Comparative Example 1), and the performance differences between (a) and (b) were compared. Specifically, in (a), the design was performed to maximize the average power generation (expected power generation) obtained with isotropically diffused light (corresponding to Case 1). Meanwhile, in (b), the design was performed, as in the conventional method, to maximize the power generation when light is incident perpendicularly.

[0063] Figure 6 shows a schematic diagram of an example of an eight-layer anti-reflection coating designed for an organic thin-film solar cell using SiO2 and TiO2 layers, based on the algorithm using the random initial values ​​described above. Figure 6(a) shows the result when the method of the present invention was applied, and Figure 6(b) shows the result when the conventional design method (a method for maximizing power generation at normal incidence) was applied.

[0064] As shown in Figure 6, when an eight-layer film composed of SiO2 and TiO2, which are widely used materials for anti-reflection coatings, was designed, the film thickness of each layer was optimized using this design method, and power generation efficiency in an indoor environment improved by 3.97% (relative value) compared to a case without an anti-reflection coating. This was 1.09% higher than the conventional method, demonstrating that this design method has a significant advantage over conventional methods. Furthermore, since the thickness of each layer of the anti-reflection coating was simply changed, there was no need to use new materials, and the same equipment could be used for manufacturing without changing it, so there was essentially no increase in costs.

[0065] (Example 2, Comparative Example 2) Using the algorithm that uses the random initial values ​​described above, we performed optical design for an anti-reflection coating in the case of a four-layer film using a refractive index-adjusting material (a material whose refractive index is adjusted arbitrarily by making the material porous).

[0066] Figure 7 shows a schematic diagram of an example of a four-layer anti-reflection coating with different refractive indices designed for an organic thin-film solar cell. Figure 7(a) (Example 2) shows the result when this design method was applied, and Figure 7(b) (Comparative Example 2) shows the result when the conventional design method (a method for maximizing power generation at normal incidence) was applied.

[0067] In Figure 7(b), the characteristics of the top layer (refractive index, thickness) are not shown because the thickness of the top layer converged to 0 as a result of the design (meaning that three layers are essentially sufficient). The refractive index n of the refractive index-matching material is limited to the generally adjustable range (1.05 to 2.66). This design method improved the power generation efficiency in an indoor environment by 8.57% (relative value) compared to solar cells without an anti-reflection coating. This is 1.64% higher than the conventional method, and it is clear that this design method has an even greater advantage when a refractive index-matching material is used.

Claims

1. (A) The energy density distribution g(θ) of a solar cell having an anti-reflection film with respect to the incident angle θ of isotropically diffused light on the surface of the anti-reflection film is calculated using the formula (1): [Equation 1] where θ is the angle of incidence of the isotropically diffused light on the surface of the solar cell, and g(θ) is the light energy density. Calculating based on, and determining a configuration of the anti-reflection film that maximizes the power generation efficiency of the solar cell based on the calculated energy density distribution g(θ); A method for designing an anti-reflection coating for a solar cell, comprising:

2. Determining a configuration of the anti-reflection film that maximizes the power generation efficiency of the solar cell based on the calculated energy density distribution g(θ), (B) determining an nth configuration of the anti-reflection film; (C) Based on the nth configuration of the antireflection film, the short-circuit current density J of the solar cell with respect to the incident angle θ SC (θ), or the reflectance R(λ, θ) of the entire solar cell having the anti-reflection coating with respect to the incident angle θ and wavelength λ; (D) The calculated energy density distribution g(θ) and the calculated J SC (θ) or the calculated relationship with R(λ, θ), the average value J of the short circuit current density of the solar cell is calculated. SC、ave or the average reflectance R of the solar cell ave Calculating the (E) the J calculated using an optimization engine SC、ave is maximized or the R ave determining an (n+1)th configuration of the anti-reflection coating that minimizes Including, The n is a natural number starting from 1, The J calculated using the optimization engine SC、ave Or the R ave repeating steps (C) to (E) until the change in converges within a predetermined range, thereby determining a final configuration of the antireflection film. The design method according to claim 1 .

3. The design method according to claim 2 , wherein determining the first configuration of the anti-reflection coating when n is 1 is performed using a random initial value.

4. Maximizing the power generation efficiency of the solar cell is achieved by satisfying the formula (2): [Equation 2] (In the formula, θ min and θ max are the lower and upper limits of the integral range of the incident angle, and H(θ) is the short-circuit current density J generated by the solar cell at the incident angle θ. SC (θ), or a function of the reflectance R(λ,θ) at the angle of incidence θ and wavelength λ.

3. The design method according to claim 2, wherein the evaluation function I is maximized.

5. The H(θ) is expressed by the formula (3): [Equation 3] is expressed as The evaluation function I is expressed by the formula (4): [Equation 4] The J is the average value of the short-circuit current density due to the isotropic diffused light, which is expressed as SC、ave matches Maximizing the evaluation function I is SC、ave The design method according to claim 4, wherein the method is to maximize

6. The H(θ) is expressed by the formula (5): [Equation 5] (where F(λ) is the energy density at wavelength λ of the light source used in the design, and λ min and λ max are the lower and upper limits of the wavelength range over which the integration is performed) is expressed as The evaluation function I is expressed by the formula (6): [Equation 6] The R is the average value of the reflectance under the condition of isotropic diffuse light, expressed as ave The negative value of (-R ave ) and Maximizing the evaluation function I is ave The design method according to claim 4, wherein the step of minimizing

7. The design method according to claim 2 , wherein the nth configuration of the antireflection film is the number of layers of the antireflection film, the thickness of each layer, the refractive index, or a combination thereof.

8. A method for producing an anti-reflection film for a solar cell, comprising the design method according to any one of claims 1 to 7.

9. A method for manufacturing a solar cell provided with an anti-reflection film, comprising the design method according to any one of claims 1 to 7.

10. On the computer, (A) The energy density distribution g(θ) of a solar cell having an anti-reflection film with respect to the incident angle θ of isotropically diffused light on the surface of the anti-reflection film is calculated using the formula (1): [Equation 7] where θ is the angle of incidence of the isotropically diffused light on the surface of the solar cell, and g(θ) is the light energy density. A calculation process that calculates based on A configuration determination process for determining a configuration of the anti-reflection film that maximizes the power generation efficiency of the solar cell based on the calculated energy density distribution g(θ). A design program for anti-reflective coatings for solar cells.

11. A configuration determination process for determining a configuration of the anti-reflection film that maximizes the power generation efficiency of the solar cell based on the calculated energy density distribution g(θ), (B) an nth configuration determination process for determining an nth configuration of the antireflection film; (C) Based on the nth configuration of the antireflection film, the short-circuit current density J of the solar cell with respect to the incident angle θ SC (θ), or J which calculates the reflectance R(λ, θ) of the entire solar cell having the anti-reflection coating for the incident angle θ and wavelength λ. SC (θ) or reflectance R(λ, θ), (D) The calculated energy density distribution g(θ) and the calculated J SC (θ) or the calculated relationship with R(λ, θ), the average value J of the short circuit current density of the solar cell is calculated. SC、ave or the average reflectance R of the solar cell ave Calculate R ave Calculation process, and (E) the J calculated using an optimization engine SC、ave is maximized or the R ave (n+1)-th configuration determination process for determining the (n+1)-th configuration of the anti-reflection film that minimizes Including, The n is a natural number starting from 1, The J calculated using the optimization engine SC、ave Or the R ave repeating steps (C) to (E) until the change in converges within a predetermined range, thereby determining a final configuration of the antireflection film. The design program according to claim 10.

12. The design program according to claim 11 , wherein determining the first configuration of the anti-reflection coating when n is 1 is performed using a random initial value.

13. Maximizing the power generation efficiency of the solar cell is achieved by satisfying the formula (2): [Equation 8] (In the formula, θ min and θ max are the lower and upper limits of the integral range of the incident angle, and H(θ) is the short-circuit current density J generated by the solar cell at the incident angle θ. SC (θ), or a function of the reflectance R(λ,θ) at the angle of incidence θ and wavelength λ.

12. The design program according to claim 11, wherein the evaluation function I is maximized.

14. The H(θ) is expressed by the formula (3): [Equation 9] is expressed as The evaluation function I is expressed by the formula (4): [Equation 10] The J is the average value of the short-circuit current density due to the isotropic diffused light, which is expressed as SC、ave matches Maximizing the evaluation function I is SC、ave The design program according to claim 13, wherein the design program is to maximize

15. The H(θ) is expressed by the formula (5): [0011] (where F(λ) is the energy density at wavelength λ of the light source used in the design, and λ min and λ max are the lower and upper limits of the wavelength range over which the integration is performed), is expressed as The evaluation function I is expressed by the formula (6): [0012] The R is the average value of the reflectance under the condition of isotropic diffuse light, expressed as ave The negative value of (-R ave ) and Maximizing the evaluation function I is ave The design program according to claim 13, wherein the minimization of

16. The design program according to claim 11 , wherein the nth configuration of the antireflection film is the number of layers of the antireflection film, the thickness of each layer, the refractive index of each layer, or a combination thereof.

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