Gas barrier film and photoelectric conversion device

Abstract

Provided are a gas barrier film having high barrier properties and high light capture efficiency, and a photoelectric conversion device having a long life and excellent photoelectric conversion efficiency. [Solution] According to an embodiment, a gas barrier film including a gas barrier layer is provided. The gas barrier layer includes one or more multilayer films including a light-transmitting first layer and a silicon nitride film adjacent to the first layer. The first layer is located on one main surface of the gas barrier layer, and the silicon nitride film is located on the other main surface of the gas barrier layer. The refractive index of the gas barrier layer increases from the main surface where the first layer is located to the other main surface.

Description

[Technical Field]

[0001] FIELD OF THE INVENTION The present invention relates to a gas barrier film and a photoelectric conversion device. [Background technology]

[0002] Gas barriers are widely used in electronic devices, packaging, and other applications. For example, water vapor barriers are used in photoelectric conversion devices such as perovskite solar cells and organic electroluminescence (OLED) elements, as well as nonaqueous electrolyte batteries. In food and pharmaceutical packaging, oxygen barriers are used to prevent deterioration of the contents.

[0003] Known gas barrier films include films including a gas barrier layer formed on a substrate by vacuum deposition, such as atomic layer deposition (ALD) or chemical vapor deposition (CVD), and films including a gas barrier layer formed by applying a coating liquid containing a silicon compound, such as polysilazane, to a substrate and then modifying the coating by irradiating with vacuum ultraviolet (VUV) light. It is also known to form a multilayer structure by stacking multiple gas barrier layers. For example, a gas barrier film has been reported in which a gas barrier layer is formed on a substrate by CVD, and then a coating liquid containing a silicon compound is applied thereon and modified by VUV light to form another gas barrier layer.

[0004] Vacuum film formation such as CVD requires expensive equipment, takes a long time to form the film, and has low productivity. In addition, chemical vapor deposition films have poor particle coverage on the substrate, which causes defects at the particle positions, resulting in low barrier properties for the gas barrier layer. Regarding the modification process of polysilazane, processing in an oxygen atmosphere results in the formation of a silicon oxide film (SiO x (x>0) film), and when processed in a nitrogen atmosphere, a silicon nitride film (SiN x (x>0) film) is obtained by using a coating solution and vacuum modification treatment. x Although the film provides good barrier properties, the SiN obtained by using a coating liquid and vacuum modification treatment x For membranes, a more efficient 10 -5 g / m 2It has been reported that an ultra-high barrier property of less than d (grams / square meter·day) can be achieved. [Prior art documents] [Patent documents]

[0005] [Patent Document 1] Japanese Patent Application Laid-Open No. 2016-137710 [Non-patent literature]

[0006] [Non-Patent Document 1] Solution-Processed Gas Barriers with Glass-Like Ultrahigh Barrier Performance by Tatsuki Sasaki et al., Advanced Materials Interfaces 2022, 9, 2201517 Summary of the Invention [Problem to be solved by the invention]

[0007] Provided are a gas barrier film having high barrier properties and high light capture efficiency, and a photoelectric conversion device having a long life and excellent photoelectric conversion efficiency. [Means for solving the problem]

[0008] According to an embodiment, a gas barrier film including a gas barrier layer is provided. The gas barrier layer includes one or more multilayer films including a light-transmitting first layer and a silicon nitride film adjacent to the first layer. The first layer is located on one main surface of the gas barrier layer, and the silicon nitride film is located on the other main surface of the gas barrier layer. The refractive index of the gas barrier layer increases from the main surface side where the first layer is located to the other main surface side. In the gas barrier film, the silicon nitride film has a gradation in which the refractive index changes continuously and monotonically from 1.54 to 1.7 throughout the entire silicon nitride film in the thickness direction, from the interface with the first layer to the back side of the silicon nitride film.

[0009] According to an embodiment, there is provided a photoelectric conversion device comprising a light-transmitting first electrode, a second electrode, a photoelectric conversion layer, and the gas barrier film according to the embodiment. The photoelectric conversion layer is located between the first electrode and the second electrode. The first electrode is adjacent to the gas barrier layer on the other main surface side where the silicon nitride film is located.

[0010] According to another embodiment, there is provided a photoelectric conversion device comprising a second electrode, a photoelectric conversion layer, and a gas barrier film. The gas barrier film is the gas barrier film according to the above embodiment, further comprising a transparent electrode adjacent to the gas barrier layer on the other main surface side where the silicon nitride film is located. The photoelectric conversion layer is located between the transparent electrode and the second electrode. [Brief explanation of the drawings]

[0011] [Figure 1] Conceptual diagram showing Snell's law. [Figure 2] 1 is a schematic cross-sectional view showing a first example of a gas barrier film according to an embodiment. [Figure 3] FIG. 3 is a schematic cross-sectional view showing a second example of a gas barrier film according to an embodiment. [Figure 4] FIG. 4 is a schematic cross-sectional view showing a third example of a gas barrier film according to an embodiment. [Figure 5] FIG. 4 is a schematic cross-sectional view showing a fourth example of a gas barrier film according to an embodiment. [Figure 6] 1 is a schematic cross-sectional view showing a first example of a solar cell device according to an embodiment. [Figure 7] FIG. 4 is a schematic cross-sectional view showing a second example of a solar cell device according to an embodiment. DETAILED DESCRIPTION OF THE INVENTION

[0012] (First embodiment) According to the first embodiment, a gas barrier film is provided. The gas barrier film includes a light-transmitting first layer and a silicon nitride film (SiN xThe gas barrier layer includes one or more multilayer films including a silicon nitride film (x>0). A light-transmitting first layer is located on one main surface of the gas barrier layer, and a silicon nitride film is located on the other main surface. The refractive index of the gas barrier layer increases from the main surface side where the first layer is located to the other main surface side.

[0013] The first layer and silicon nitride film that make up the gas barrier layer of the gas barrier film both exhibit translucency. The refractive index of the gas barrier layer increases from one main surface to the other. Figure 1 shows this concept, as expressed by Snell's law (relative refractive index n 12 As shown by the equation (n2 / n1=sinα / sinβ), at the interface 100 between a medium 101 with a low refractive index n1 and a medium 102 with a high refractive index n2, the angle of emergence β of emitted light 112 is smaller than the angle of incidence α of incident light 111 at the interface 100 due to light passing from the medium 101 to the medium 102. The angle of reflection γ of reflected light 113 is equal to the angle of incidence α. In the gas barrier film according to the first embodiment, due to the refractive index gradation in the gas barrier layer, the direction of exiting light from the main surface with a high refractive index is closer to perpendicular to the main surface of the gas barrier layer than the direction of incident light to the main surface with a low refractive index. In other words, light irradiated onto the gas barrier film from various directions can be emitted from the backside in a uniform direction. In this way, the gas barrier film can efficiently capture light. Therefore, when the gas barrier film is applied to a device that utilizes light, such as a solar cell device, the efficiency of light capture into the device can be improved.

[0014] The gas barrier film may be a gas barrier film with a transparent electrode, which further includes a transparent electrode. The transparent electrode is adjacent to the gas barrier layer, for example, on the main surface of the gas barrier layer where the silicon nitride film is located. By providing a transparent electrode on the main surface of the gas barrier layer that has a higher refractive index, when the transparent electrode is used as an electrode of a photoelectric conversion device such as a solar cell device, the efficiency of light capture into the device can be improved. It is preferable that the transparent electrode has a refractive index equal to or greater than the maximum refractive index of the gas barrier layer. The light capture efficiency can be further increased by further extending the refractive index gradation in the gas barrier layer to the transparent electrode.

[0015] The gas barrier film may further include a substrate having a film shape. The first layer may be provided on the surface of the substrate and may function as a planarizing film. The substrate may also be made of a light-transmitting material.

[0016] Examples of gas barrier films according to embodiments will be described with reference to FIGS. 2 to 5. The gas barrier films shown in each figure include a substrate. The gas barrier layer of the gas barrier films shown in each figure includes one multilayer film including a first layer and a silicon nitride film. In each figure, the thickness direction of the gas barrier film is parallel to the z-axis direction. The surface direction of the gas barrier film is parallel to the plane defined by the x-axis and y-axis directions. The x-axis, y-axis, and z-axis directions intersect perpendicularly to one another. Furthermore, in each figure, components that are common to multiple figures are designated by the same reference numerals, and their description will be omitted.

[0017] The gas barrier film 1 shown in FIG. 2 includes a substrate 2 and a multilayer film 3 serving as a gas barrier layer. The multilayer film 3 includes a first layer 4 and a silicon nitride film 5. The substrate 2 has a layered or film shape. The substrate 2 has two main surfaces (principal surfaces) 2a and 2b that intersect in the thickness direction (z-axis direction). Each of the surfaces 2a and 2b is parallel to the xy plane. It can also be said that the other surface 2b is located on the opposite side of the surface 2a. The substrate 2 is optically transparent. The substrate 2 is formed from, for example, polyethylene terephthalate (PET), polycarbonate, ethylene tetrafluoroethylene (ETFE), polyimide (PI), polyethylene naphthalate (PEN), or the like.

[0018] The multilayer film 3 is provided on one surface of the substrate 2. In the case of FIG. 2, the multilayer film 3 is laminated on one surface 2a of the substrate 2. The multilayer film 3 has barrier properties against gases such as water vapor and oxygen. The multilayer film 3 essentially consists of, for example, a first layer 4 as a planarizing film and a silicon nitride film 5. The first layer 4 and the silicon nitride film 5 each have two surfaces that intersect with the thickness direction (z-axis direction) as their main surfaces (principal surfaces). The two surfaces of the multilayer film 3 (gas barrier layer) that intersect with the thickness direction (z-axis direction) are defined as main surfaces (principal surfaces) 3a and 3b.

[0019] The light-transmitting first layer 4 is provided on one surface 2a of the substrate 2. The first layer 4 may be a film of a silicone compound, a silicon oxide film (SiO xThe first layer 4 may be one selected from the group consisting of a (x>0) film), an organic-inorganic hybrid film, and an organic film. The first layer 4 can be obtained, for example, by applying a coating agent containing the material of the above film to one surface 2a of the substrate 2 and drying it. The silicon oxide film can also be obtained, for example, by modifying a silicone compound film or a polysilazane compound film with vacuum ultraviolet light in an O2 atmosphere. That is, the silicon oxide film can be a silicon oxide film modified from a silicone compound or a silicon oxide film modified from a polysilazane compound. A specific example of the latter is a film obtained by a method including applying a perhydropolysilazane (PHPS) solution to the substrate 2 by, for example, spin coating, removing the solvent by, for example, pre-baking, and then irradiating the solution with vacuum ultraviolet light (VUV) in an O2 atmosphere. SiO2 can be obtained by irradiating a PHPS film formed by applying and drying a PHPS solution with vacuum ultraviolet light at a wavelength of 172 nm in an O2 atmosphere at room temperature. x An example of the reaction for producing the film is shown in Chemical Formula 1 below. As shown in Chemical Formula 1, Si-O bonds are formed to form SiO x As a result of the generation of NH3, NH3 is released. Instead of using vacuum ultraviolet light for modification, films of silicone compounds or polysilazane compounds can also be modified to obtain silicon oxide films by heating them in an O2 atmosphere.

[0020] [ka]

[0021] Since the PHPS film is formed on the substrate 2 by coating, a flat surface can be obtained even if the substrate 2 has unevenness due to the presence of particles, etc. Therefore, the first layer 4 serves as a flattening film. Furthermore, forming the PHPS film by coating can reduce the production costs of the film.

[0022] The silicon nitride film 5 is provided on a surface of the first layer 4 that is parallel to the xy plane. The silicon nitride film 5 can be obtained, for example, by modifying a polysilazane compound film with vacuum ultraviolet light in an N2 atmosphere. Specifically, it can be obtained by a method including applying a PHPS solution onto the first layer 4 by, for example, spin coating, removing the solvent by, for example, pre-baking, and then irradiating the PHPS film with vacuum ultraviolet light in an N2 atmosphere at room temperature. The PHPS film formed by applying and drying the PHPS solution is irradiated with vacuum ultraviolet light at a wavelength of 172 nm in an N2 atmosphere at room temperature to form a SiN x An example of the reaction for producing the film is shown in Chemical Formula 2 below. As shown in Chemical Formula 2, Si-N bonds are formed to form SiN x As a result of this, H2 is released.

[0023] [ka]

[0024] The silicon nitride film 5 obtained by the modification process has a refractive index that changes in the thickness direction of the gas barrier film (for example, the z-axis direction). Because vacuum ultraviolet light mainly modifies the surface layer of the film, the SiN reaction occurs continuously from the surface layer toward the first layer 4 side. Therefore, the silicon nitride film 5 has a gradation in which the silicon nitride concentration is higher on the surface layer side (the main surface 3b side of the multilayer film 3) than on the first layer 4 side. Therefore, the silicon nitride film 5 is characterized by a refractive index that increases from the first layer 4 side toward the surface layer side.

[0025] The refractive index of the silicon nitride film 5 is set to be greater than the refractive index of the first layer 4. Because the exit angle (β) of light passing from the first layer 4 to the silicon nitride film 5 at the interface between the first layer 4 and the silicon nitride film 5 is smaller than the incident angle (α), the light is introduced into the silicon nitride film 5 with its traveling direction approaching a direction perpendicular to the main surfaces 3a and 3b of the multilayer film 3. Further ahead, the refractive index of the silicon nitride film 5 increases toward the main surface 3b of the multilayer film 3. That is, the refractive index increases throughout the entire multilayer film 3 from the main surface 3a facing the substrate 2 toward the main surface 3b on the back side. Therefore, light that enters the multilayer film 3 from the main surface 3a facing the substrate 2 at various angles is converged and emitted in a direction nearly perpendicular to the main surface 3b on the back side.

[0026] In a specific example of the gas barrier film, the minimum refractive index of the silicon nitride film 5 is 1.54, and the maximum refractive index of the silicon nitride film 5 is 1.7. For example, the refractive index can vary from 1.54 to 1.7 from the interface with the light-transmitting first layer 4 to the back side of the silicon nitride film 5. In another example, the refractive index of the gas barrier layer increases from 1.4 to 1.7 from the main surface side where the first layer is located to the other main surface side.

[0027] The gas barrier layer may include multiple multilayer films 3 each consisting of a first layer 4 and a silicon nitride film 5. For example, the gas barrier layer may be configured by alternately arranging multiple first layers and multiple silicon nitride films. However, care should be taken so that the refractive index of the first layer located on one main surface of the gas barrier layer is lowest and the refractive index of the silicon nitride film located on the back main surface is highest, with the refractive indexes increasing sequentially between them. For example, the refractive index of the silicon nitride film included in the multilayer film in which the first layer is located on one main surface of the gas barrier layer may be 1.54, and the refractive index of the silicon nitride film included in the multilayer film located on the other main surface of the gas barrier layer may be 1.7.

[0028] The gas barrier film 1 shown in FIG. 2 has excellent barrier properties against gases such as water vapor and oxygen. The gas barrier film 1 is also transparent to visible light and can efficiently capture light. Furthermore, because the multilayer film 3 includes the first layer 4 in addition to the silicon nitride film 5, sufficient barrier function can be achieved even if the thicknesses of the first layer 4 and the silicon nitride film 5 are thin. As a result, defects such as cracks in the first layer 4 and the silicon nitride film 5 can be avoided. The silicon nitride film 5 alone exhibits a certain level of barrier properties. However, because thicker silicon nitride films tend to crack, it is difficult to improve the barrier properties by thickening the silicon nitride film 5. By forming the multilayer film 3, in which the first layer 4 and the silicon nitride film 5 are superimposed, as a gas barrier layer, superior barrier properties can be achieved compared to the silicon nitride film 5 alone.

[0029] Next, the gas barrier film shown in Fig. 3 will be described. The gas barrier film 6 shown in Fig. 3 includes a substrate 2, a multilayer film 3, and a second layer 7. Details of the substrate 2 and the multilayer film 3 are as described in Fig. 2.

[0030] The second layer 7 is provided on the other surface 2b of the substrate 2. In the case of FIG. 3, the second layer 7 is laminated on the other surface 2b of the substrate 2. The second layer 7 is optically transparent. The second layer 7 can reduce the difference between the stress applied to one surface 2a of the substrate 2 and the stress applied to the other surface 2b of the substrate 2. Therefore, the second layer 7 can prevent the substrate 2 from warping due to the stress difference. The second layer 7 is formed, for example, from the same material as the first layer 4. That is, the optically transparent second layer 7 can also be one selected from the group consisting of a silicone compound film, a silicon oxide film (e.g., a silicon oxide film modified with a silicone compound, a silicon oxide film modified with a polysilazane compound), an organic-inorganic hybrid film, and an organic film.

[0031] The gas barrier film 6 shown in FIG. 3 has excellent barrier properties against gases such as water vapor and oxygen. The gas barrier film 6 is also transparent to visible light and can efficiently capture light. The gas barrier film 6 has a first layer 4 of a multilayer film 3 provided on one side of a substrate 2, and a second layer 7 provided on the other side of the substrate 2. This reduces the difference between the stress applied to one side of the substrate 2 and the stress applied to the other side, thereby suppressing warping of the substrate 2.

[0032] In addition, in Figure 3, an example is described in which the first layer 4 and the second layer 7 are directly laminated on both sides of the base material 2, but this is not limited to this, and another layer such as an adhesive layer may be interposed between the base material 2 and the first layer 4 or the second layer 7.

[0033] Next, the gas barrier film shown in Fig. 4 will be described. The gas barrier film 8 with transparent electrode shown in Fig. 4 includes a substrate 2, a multilayer film 3, and a transparent electrode 12. Details of the substrate 2 and the multilayer film 3 are as described in Fig. 2.

[0034] The transparent electrode 12 is provided on the main surface 3b parallel to the xy plane of the multilayer film 3 serving as a gas barrier layer. One surface of the transparent electrode 12 parallel to the xy plane is in contact with the main surface 3b. In this way, the transparent electrode 12 is adjacent to the gas barrier layer on the main surface side where the silicon nitride film 5 is located at the top.

[0035] Examples of the transparent electrode 12 include films made of materials that are optically transparent and electrically conductive, such as indium tin oxide (ITO), zinc oxide (ZnO), tin dioxide (SnO2), and fluorine-doped tin oxide (FTO).

[0036] The refractive index of the transparent electrode 12 is preferably equal to or greater than the maximum refractive index of the gas barrier layer. Because the exit angle (β) of light passing through the silicon nitride film 5 at the interface between the gas barrier layer (multilayer film 3) and the transparent electrode 12 and penetrating into the transparent electrode 12 is smaller than the incident angle (α), the light is introduced into the transparent electrode 12 with its traveling direction approaching a direction perpendicular to the major surfaces 3a and 3b of the multilayer film 3. Therefore, the light that enters the transparent electrode 12 from the major surface 3b of the multilayer film 3 is focused on the back side in a direction even closer to a perpendicular direction to the major surface 3b and then emitted. The refractive index of the transparent electrode 12 may be, for example, 1.7 or greater. In one example, the refractive index of the transparent electrode 12 may be 2.0 or less.

[0037] 4 has excellent barrier properties against gases such as water vapor and oxygen. In addition, the gas barrier film 8 is transparent to visible light and can efficiently capture light.

[0038] Next, the gas barrier film shown in Fig. 5 will be described. The gas barrier film 9 with transparent electrode shown in Fig. 5 includes a substrate 2, a multilayer film 3, a second layer 7, and a transparent electrode 12. Details of the substrate 2 and the multilayer film 3 are as described in Fig. 2. Details of the second layer 7 are as described in Fig. 3. Details of the transparent electrode 12 are as described in Fig. 4.

[0039] The gas barrier film 9 with a transparent electrode shown in Figure 5 has excellent barrier properties against gases such as water vapor and oxygen. The gas barrier film 9 is also transparent to visible light and can efficiently capture light. In addition, the gas barrier film 9 can suppress warping of the substrate 2.

[0040] The gas barrier film of the first embodiment is not particularly limited in its use, but is preferably used in applications requiring gas barrier properties against water vapor, oxygen, etc. The gas barrier film of the first embodiment can be used, for example, in photoelectric conversion devices. Examples of photoelectric conversion devices include solar cell devices, optical sensors, and optical memories.

[0041] The gas barrier film of the first embodiment described above includes a gas barrier layer including one or more multilayer films including a light-transmitting first layer and an adjacent silicon nitride film. The refractive index of the gas barrier layer increases from one main surface side to the other main surface side. This allows the gas barrier film of the first embodiment to have high light-capturing performance while maintaining gas barrier performance.

[0042] (Second embodiment) According to the second embodiment, a photoelectric conversion device is provided. This photoelectric conversion device includes the gas barrier film of the first embodiment. In addition to the gas barrier film, the photoelectric conversion device further includes a light-transmitting first electrode, a second electrode, and a photoelectric conversion layer located therebetween. The first electrode is adjacent to the gas barrier layer on the main surface where the silicon nitride film is located. This photoelectric conversion device can also be considered to include the gas barrier film with the transparent electrode described in the first embodiment. That is, the first electrode corresponds to the transparent electrode described in the first embodiment. From this perspective, the photoelectric conversion device further includes, in addition to the gas barrier film including the transparent electrode, a second electrode and a photoelectric conversion layer located between the transparent electrode and the second electrode.

[0043] Such a photoelectric conversion device may be, for example, a solar cell device such as a perovskite solar cell, etc. The photoelectric conversion device may be an optical sensor, an optical memory, or the like, in addition to a solar cell.

[0044] As described in the first embodiment, the gas barrier layer included in the gas barrier film has a gradation of refractive index that increases from one main surface side to the other main surface side. Therefore, the direction in which light passing through the gas barrier layer exits approaches a perpendicularity to the exit surface in the direction in which the refractive index increases. Therefore, by orienting the main surface of the gas barrier layer, where the refractive index is at its maximum, toward the photoelectric conversion layer, the light capture efficiency into the photoelectric conversion device can be improved.

[0045] An example in which the photoelectric conversion device of the embodiment is applied to a solar cell device will be described with reference to Figures 6 and 7. In each figure, the thickness direction of the solar cell device is parallel to the z-axis direction. The surface direction of the solar cell device is parallel to a plane defined by the x-axis and y-axis directions. The x-axis, y-axis, and z-axis directions intersect perpendicularly with each other. Furthermore, in each figure, components that are common to multiple figures are assigned the same reference numerals and descriptions thereof will be omitted.

[0046] The solar cell device 20 shown in FIG. 6 includes the gas barrier film 1 of the first embodiment, a transparent electrode 12 as a first electrode, a hole transport layer 13, a photoelectric conversion layer 14, an electron transport layer 15, a cathode 16 as a second electrode, an adhesive layer 17, and a backsheet 18. The details of the gas barrier film 1 and the transparent electrode 12 are as described in the first embodiment. The transparent electrode 12, the hole transport layer 13, the photoelectric conversion layer 14, the electron transport layer 15, and the cathode 16 each have two main surfaces (principal surfaces) that intersect with the thickness direction (z-axis direction). Each surface is parallel to the xy plane. The transparent electrode 12 is provided on a main surface 3b parallel to the xy plane of the multilayer film 3 serving as a gas barrier layer of the gas barrier film 1. One surface of the transparent electrode 12 parallel to the xy plane is in contact with the main surface 3b. In this way, the transparent electrode 12 (first electrode) is adjacent to the gas barrier layer on the main surface side where the silicon nitride film 5 is located on top. A laminate of the gas barrier film 1 and the transparent electrode 12 can be considered as a gas barrier film 8 with a transparent electrode. A hole transport layer 13, a photoelectric conversion layer 14, an electron transport layer 15, and a cathode 16 are provided in this order on the other surface of the transparent electrode 12 parallel to the xy plane. A back sheet 18 is fixed to one surface of the cathode 16 parallel to the xy plane by an adhesive layer 17. Light such as sunlight or illumination is irradiated onto the other surface 2b of the substrate 2 of the gas barrier film 1 from a first direction 19, for example.

[0047] Examples of the transparent electrode 12 as the first electrode include films made of materials that are optically transparent and electrically conductive, such as indium tin oxide (ITO), zinc oxide (ZnO), tin dioxide (SnO2), and fluorine-doped tin oxide (FTO).

[0048] The hole transport layer 13 has functions such as blocking electrons generated in the photoelectric conversion layer 14 and transporting holes selectively and efficiently to the transparent electrode 12 .

[0049] An example of the photoelectric conversion layer 14 includes a perovskite layer. An example of a perovskite compound is methylammonium lead iodide (CH3NH3PbI3).

[0050] The electron transport layer 15 has functions such as blocking holes generated in the photoelectric conversion layer 14 and transporting electrons selectively and efficiently to the cathode 16 .

[0051] The cathode 16 as the second electrode is made of a material that is electrically conductive and, in some cases, optically transparent. The cathode 16 may be, for example, a layer containing Ti and / or Al. .

[0052] When light is irradiated onto the other surface 2b of the substrate 2 of the gas barrier film 1 (or the gas barrier film 8 with a transparent electrode) from the first direction 19 in the solar cell device 20 having the above structure, and the irradiated light is absorbed by the photoelectric conversion layer 14, electrons and holes that pair with them are generated. Of the generated electrons and holes, for example, the electrons are collected by the cathode 16 via the electron transport layer 15. The holes are collected by the transparent electrode 12 via the hole transport layer 13. In this way, a photoelectric conversion reaction occurs.

[0053] The gas barrier film 1 has a high light capture efficiency from the first direction 19, and can efficiently transmit light incident on the other surface 2b of the substrate 2 at various angles to the photoelectric conversion layer 14. As a result, the photoelectric conversion efficiency of the solar cell device 20 can be improved. In addition, the gas barrier film 1 has excellent barrier properties against gases such as water vapor and oxygen, and can therefore prevent gases from entering the solar cell device 20. As a result, the life of the solar cell device can be extended.

[0054] It is preferable that the transparent electrode 12 has a refractive index equal to or greater than the maximum refractive index of the gas barrier layer. By extending the gradation of the refractive index of the gas barrier film, which increases from the other surface 2b of the substrate 2 toward the photoelectric conversion layer 14, to the transparent electrode 12, the light capture efficiency is further increased. The refractive index of the transparent electrode 12 can be, for example, 1.7 or more. According to one example, the refractive index of the transparent electrode 12 can be 2.0 or less.

[0055] Next, a solar cell device 21 shown in FIG. 7 will be described. The solar cell device 21 differs from the solar cell device 21 described with reference to FIG. 6 in that it includes the gas barrier film 6 of the first embodiment instead of the gas barrier film 1 of the first embodiment. Alternatively, it can be said that the solar cell device 21 includes the gas barrier film 9 of the first embodiment instead of the gas barrier film 8 of the first embodiment with a transparent electrode. Details of the gas barrier film 6 (or the gas barrier film 9 with a transparent electrode) are as described in the first embodiment. Details of the solar cell device 21 are the same as those of the solar cell device 20 described with reference to FIG. 6, except for the gas barrier film 6 (or the gas barrier film 9 with a transparent electrode).

[0056] When light is irradiated onto the second layer 7 of the gas barrier film 6 (or the gas barrier film 9 with a transparent electrode) of the solar cell device 21 having the above structure from the first direction 19, for example, a photoelectric conversion reaction occurs in the same manner as in the solar cell device 20 described above. The gas barrier film 6 has a high light capture efficiency for light from the first direction 19, and can efficiently transmit light incident at various angles on the other surface 2b of the substrate 2 to the photoelectric conversion layer 14. As a result, the photoelectric conversion efficiency of the solar cell device 20 can be improved. Furthermore, the second layer 7 of the gas barrier film 6 can suppress warping of the substrate 2, thereby preventing deformation such as warping of the solar cell device 21. In addition, the gas barrier film 6 has excellent barrier properties against gases such as water vapor and oxygen, and can therefore suppress the intrusion of gases into the solar cell device 21. As a result, the life of the solar cell device can be extended.

[0057] In the above example, the first electrode (transparent electrode 12) is the anode and the second electrode is the cathode 16, but the arrangement of these electrodes may be reversed. That is, the first electrode (transparent electrode 12) may be the cathode and the second electrode may be the anode. In this case, the positions of the hole transport layer 13 and the electron transport layer 15 are also reversed.

[0058] Although not shown, a gas barrier film may be provided on the second electrode side in addition to the first electrode side. The backsheet 18 may be omitted, and instead, a gas barrier film may be superimposed on the second electrode. If a translucent electrode, i.e., a transparent electrode, is used as the second electrode, light can be captured from the second electrode side as well. Therefore, light can be received from both sides of the solar cell device. In this case, it is preferable that the refractive index of the second electrode is equal to or greater than the maximum refractive index of the silicon nitride film of the gas barrier film adjacent to the second electrode, i.e., equal to or greater than the maximum refractive index of the gas barrier layer. As with the first electrode side, the refractive index increases from the surface of the outermost layer of the gas barrier film provided on the second electrode toward the second electrode, thereby increasing the light capture efficiency.

[0059] As described above, the photoelectric conversion device of the second embodiment includes the gas barrier film of the first embodiment, which prevents the intrusion of gases such as water vapor and oxygen and has a high light capture efficiency, resulting in a long lifespan and excellent photoelectric conversion efficiency of the photoelectric conversion device.

[0060] Although several embodiments of the present invention have been described, these embodiments are presented as examples and are not intended to limit the scope of the invention. These novel embodiments can be embodied in various other forms, and various omissions, substitutions, and modifications can be made without departing from the spirit of the invention. These embodiments and their modifications are included within the scope and spirit of the invention, and are also included in the scope of the invention and its equivalents as defined in the claims. The original claims of this application are set forth below. [1] A translucent first layer; a gas barrier layer including one or more multilayer films including the first layer and an adjacent silicon nitride film, the first layer being located on one main surface of the gas barrier layer, and the silicon nitride film being located on the other main surface of the gas barrier layer; A gas barrier film in which the refractive index of the gas barrier layer increases from the main surface on which the first layer is located to the other main surface. [2] The gas barrier film according to [1], wherein the silicon nitride film has a minimum refractive index of 1.54 and a maximum refractive index of 1.7. [3] The gas barrier film according to [1], wherein the refractive index of the gas barrier layer increases from 1.4 to 1.7 from the main surface side where the first layer is located to the other main surface side. [4] The gas barrier film according to any one of [1] to [3], wherein the first layer is one selected from the group consisting of a silicone compound film, a silicon oxide film, an organic-inorganic hybrid film, and an organic film. [5] The gas barrier film according to any one of [1] to [3], further comprising a transparent electrode adjacent to the gas barrier layer on the other main surface side where the silicon nitride film is located, the transparent electrode having a refractive index equal to or greater than the maximum refractive index of the gas barrier layer. [6] a light-transmitting first electrode; A second electrode; a photoelectric conversion layer between the first electrode and the second electrode; [1] to [3], and the gas barrier film according to any one of [1] to [3]. wherein the first electrode is adjacent to the gas barrier layer on the other main surface side where the silicon nitride film is located. [7] The gas barrier film according to [5]. A second electrode; a photoelectric conversion layer between the transparent electrode and the second electrode; A photoelectric conversion device comprising: [Explanation of symbols]

[0061] 1, 6, 8, 9...gas barrier film, 2...substrate, 2a, 2b...surface (main surface), 3...multilayer film, 3a, 3b...surface (main surface), 4...first layer, 5...silicon nitride film, 7...second layer, 12...transparent electrode, 13...hole transport layer, 14...photoelectric conversion layer, 15...electron transport layer, 16...cathode, 17...adhesive layer, 18...backsheet, 19...first direction, 20, 21...solar cell device, 100...interface, 101, 102...medium, 111...incident light, 112...emitted light, 113...reflected light.

Claims

1. a translucent first layer; a gas barrier layer including one or more multilayer films including the first layer and an adjacent silicon nitride film, the first layer being located on one main surface of the gas barrier layer, and the silicon nitride film being located on the other main surface of the gas barrier layer; The refractive index of the gas barrier layer increases from the main surface side where the first layer is located to the other main surface side, and the refractive index of the silicon nitride film has a gradation that changes monotonically and continuously from 1.54 to 1.7 throughout the entire thickness direction of the silicon nitride film, from the interface side with the first layer to the back side of the silicon nitride film.

2. 2. The gas barrier film according to claim 1, wherein the refractive index of said gas barrier layer increases from 1.4 to 1.7 from the main surface side where said first layer is located to the other main surface side.

3. 2. The gas barrier film according to claim 1, wherein the interface between said first layer and said silicon nitride film is flat.

4. 4. The gas barrier film according to claim 1, wherein the first layer is one selected from the group consisting of a silicone compound film, a silicon oxide film, an organic-inorganic hybrid film, and an organic film.

5. a light-transmitting substrate having the layer on one surface thereof; a light-transmitting second layer provided on the other surface of the substrate, The gas barrier film according to claim 1 , wherein the second layer is one selected from the group consisting of a silicone compound film, a silicon oxide film, an organic-inorganic hybrid film, and an organic film.

6. 4. The gas barrier film according to claim 1, further comprising a transparent electrode adjacent to the gas barrier layer on the other main surface side where the silicon nitride film is located, the transparent electrode having a refractive index equal to or greater than the maximum refractive index of the gas barrier layer.

7. a light-transmitting first electrode; A second electrode; a photoelectric conversion layer between the first electrode and the second electrode; The gas barrier film according to any one of claims 1 to 3. wherein the first electrode is adjacent to the gas barrier layer on the other main surface side where the silicon nitride film is located.

8. The gas barrier film according to claim 6. A second electrode; a photoelectric conversion layer between the transparent electrode and the second electrode; A photoelectric conversion device comprising:

Images