Photoelectric conversion element, photoelectric conversion module, and method for manufacturing photoelectric conversion element

Abstract

Provided are a photoelectric conversion element, a photoelectric conversion module, and a method for manufacturing a photoelectric conversion element that can prevent a perovskite precursor solution from leaking when dropped. [Solution] The photoelectric conversion element 10 includes a first electrode 11 and a second electrode 14, a photoelectric conversion layer 13 provided between the first electrode 11 and the second electrode 14, and a protrusion 15 formed to surround the periphery of the photoelectric conversion layer 13. The photoelectric conversion layer 13 includes a porous layer (a first porous layer 131 and a second porous layer 132) and a perovskite compound 133 formed in the voids of the porous layer. The protrusion 15 is in contact with the perovskite compound 133.

Description

[Technical Field]

[0001] The present disclosure relates to a photoelectric conversion element using a perovskite compound, a photoelectric conversion module, and a method for manufacturing a photoelectric conversion element. [Background technology]

[0002] Solar cells containing a photoelectric conversion layer made of perovskite compounds (perovskite solar cells) are attracting attention. In the photoelectric conversion layer of a perovskite solar cell, a porous layer is formed in the region that will become the photoelectric conversion layer, and a precursor solution of the perovskite compound (hereinafter referred to as perovskite precursor solution) is dropped onto this porous layer and dried to form the perovskite compound in the voids of the porous layer. In addition to this, techniques for improving performance, such as using a manufacturing method in which fine particles with perovskite crystals attached are sprayed, are being actively researched (Patent Document 1). [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Application Laid-Open No. 2016-178167 Summary of the Invention [Problem to be solved by the invention]

[0004] The inventors of this invention have focused on the problem that, conventionally, when dropping a perovskite precursor solution onto a porous layer, the perovskite precursor solution tends to flow out of the porous layer, preventing the perovskite compound from remaining in the voids of the porous layer. In other words, if the dropped perovskite precursor solution flows out, the formation of the perovskite compound in the voids of the porous layer becomes insufficient, resulting in a problem where the power generation performance cannot be fully realized. However, no technology has been developed to address the problem of precursor solution flow out.

[0005] This disclosure has been made in view of the above-mentioned problems, and aims to provide a photoelectric conversion element, a photoelectric conversion module, and a method for manufacturing a photoelectric conversion element that can prevent outflow when dropping a perovskite precursor solution. [Means for solving the problem]

[0006] In order to solve the above problems, the following photoelectric conversion element, photoelectric conversion module, and method for manufacturing the photoelectric conversion element are provided.

[0007] (1) Photoelectric conversion element The photoelectric conversion element disclosed herein comprises a first electrode and a second electrode, a photoelectric conversion layer provided between the first electrode and the second electrode, and a convex portion formed to surround the periphery of the photoelectric conversion layer, wherein the photoelectric conversion layer includes a porous layer and a perovskite compound formed in voids of the porous layer, and the convex portion is in contact with the perovskite compound.

[0008] (2) Photoelectric conversion module The photoelectric conversion module of the present disclosure comprises a first substrate, a photoelectric conversion element formed on the first substrate, a second substrate for arranging the photoelectric conversion element between the first substrate and the second substrate, and a sealing portion formed to surround the photoelectric conversion element between the first substrate and the second substrate, wherein the photoelectric conversion element is the photoelectric conversion element described above, and the photoelectric conversion layer of the photoelectric conversion element is sealed within a space formed by the first substrate, the second substrate, and the sealing portion.

[0009] (3) Photoelectric conversion element manufacturing method The method for manufacturing a photoelectric conversion element disclosed herein is the method for manufacturing the photoelectric conversion element described above, and is characterized by including the steps of forming the first electrode and the porous layer of the photoelectric conversion layer on a first substrate, forming the convex portion on the first substrate so as to surround the periphery of the porous layer, and dropping a precursor solution of a perovskite compound into the internal region of the convex portion to allow the precursor solution to penetrate into the porous layer, and drying the penetrated precursor solution of the perovskite compound to form the perovskite compound. [Effects of the Invention]

[0010] In the photoelectric conversion element, photoelectric conversion module, and method for manufacturing a photoelectric conversion element disclosed herein, when the perovskite precursor solution is dripped to form the photoelectric conversion layer, the convex portions function as dikes around the photoelectric conversion layer, preventing the perovskite precursor solution from leaking out of the region of the photoelectric conversion layer. This allows the perovskite compound to thoroughly fill the voids in the porous layer, resulting in high conversion efficiency in the photoelectric conversion element. [Brief explanation of the drawings]

[0011] [Figure 1] 1 is a schematic cross-sectional view of a photoelectric conversion element according to a first embodiment of the present disclosure. [Figure 2] 2A to 2C are schematic cross-sectional views illustrating a manufacturing procedure for the photoelectric conversion element of the first embodiment. [Figure 3] 2A to 2C are schematic cross-sectional views illustrating a manufacturing procedure for the photoelectric conversion element of the first embodiment. [Figure 4] 2A to 2C are schematic cross-sectional views illustrating a manufacturing procedure for the photoelectric conversion element of the first embodiment. [Figure 5] 2A to 2C are schematic cross-sectional views illustrating a manufacturing procedure for the photoelectric conversion element of the first embodiment. [Figure 6] 2A to 2C are schematic cross-sectional views illustrating a manufacturing procedure for the photoelectric conversion element of the first embodiment. [Figure 7] 5A to 5C are schematic cross-sectional views illustrating a manufacturing procedure for the photoelectric conversion element according to the second embodiment. [Figure 8]5A to 5C are schematic cross-sectional views illustrating a manufacturing procedure for the photoelectric conversion element according to the second embodiment. [Figure 9] 5A to 5C are schematic cross-sectional views illustrating a manufacturing procedure for the photoelectric conversion element according to the second embodiment. [Figure 10] 5A to 5C are schematic cross-sectional views illustrating a manufacturing procedure for the photoelectric conversion element according to the second embodiment. [Figure 11] FIG. 2 is a plan view of a photoelectric conversion element having a single cell structure. [Figure 12] FIG. 2 is a plan view of a photoelectric conversion element having a multi-cell structure. [Figure 13] FIG. 1 is a cross-sectional view showing a schematic configuration of a photoelectric conversion module in which a photoelectric conversion element is sealed. [Figure 14] FIG. 10 is a cross-sectional view showing another example of a schematic configuration of a photoelectric conversion module in which a photoelectric conversion element is sealed. [Figure 15] FIG. 10 is a cross-sectional view showing another example of a schematic configuration of a photoelectric conversion module in which a photoelectric conversion element is sealed. [Figure 16] FIG. 10 is a cross-sectional view showing another example of a schematic configuration of a photoelectric conversion module in which a photoelectric conversion element is sealed. DETAILED DESCRIPTION OF THE INVENTION

[0012] [First embodiment] DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, embodiments of the present disclosure will be described in detail with reference to the accompanying drawings. Fig. 1 shows an embodiment of the present disclosure and is a schematic cross-sectional view of a photoelectric conversion element 10. As shown in Figs.

[0013] As shown in Figure 1, the photoelectric conversion element 10 is formed on a substrate 20 and has a first electrode 11, an electron transport layer 12, a photoelectric conversion layer 13, a second electrode 14, and a protrusion 15. The first electrode 11, electron transport layer 12, photoelectric conversion layer 13, and second electrode 14 are stacked in this order from the side closest to the substrate 20. In addition, the photoelectric conversion element 10 may omit the electron transport layer 12, or a hole transport layer may be provided instead of the electron transport layer 12. Furthermore, it is preferable to have a configuration that provides both the electron transport layer 12 and the hole transport layer. Alternatively, one of the electron transport layer 12 or the hole transport layer may be provided as the upper layer of the photoelectric conversion layer 13, and the other as the lower layer of the photoelectric conversion layer 13. That is, it may be the configuration shown in Figure 1, or it may be a photoelectric conversion element with an inverse structure in which the direction of current extraction is reversed from the configuration shown in Figure 1. However, when configuring an inverted structure, the material of the second electrode 14 may need to be limited to form the electron transport layer and the hole transport layer (for example, the second electrode 14 may be a transparent electrode such as ITO).

[0014] The protrusion 15 is positioned above the electron transport layer 12 (or above the first electrode 11 if the electron transport layer 12 is omitted), surrounding the photoelectric conversion layer 13 and in contact with the outer edge of the photoelectric conversion layer 13. In this embodiment, the protrusion 15 is exemplified as a glass layer. In the photoelectric conversion element 10, when the perovskite precursor solution for forming the photoelectric conversion layer 13 is dropped, the protrusion 15 functions as a dike around the photoelectric conversion layer 13, preventing the perovskite precursor solution from flowing out of the region of the photoelectric conversion layer 13. The protrusion 15 does not need to be glass; it is sufficient that the protrusion 15 can function as a dike around the photoelectric conversion layer 13. However, using glass is desirable because, as explained in the manufacturing procedure below, it does not undergo melting or deformation due to the thermal process in the manufacturing process of the photoelectric conversion element 10, and a perovskite compound can be formed in the appropriate region as designed, or approximately as designed, using a perovskite precursor solution of the desired design volume. Here, glass may include, for example, one or more selected from silicon oxide (SiO2), tin oxide (SnO), aluminum oxide (Al2O3), zinc oxide (ZnO), alkali metal oxide (RO, R2O; R is an alkali metal), magnesium oxide (MgO), lead oxide (PbO), boron oxide (B2O3), barium oxide (BaO), calcium oxide (CaO), titanium oxide (TiO2), tellurium oxide (TeO2), vanadium oxide (V2O5), bismuth oxide (Bi2O3), and phosphorus oxide (P2O5), or may have one or more selected as its main component. Note that the chemical formulas indicated in parentheses after the compound names are representative examples and are not limited to those compositions. Furthermore, while stoichiometry is desirable for the compositional ratios shown in the example chemical formulas, it is not necessarily required. Below, an example of the manufacturing procedure for the photoelectric conversion element 10 will be explained with reference to Figures 2 to 6.

[0015] 2 is a schematic cross-sectional view showing the steps up to forming the first electrode 11 and the electron transport layer 12 on the substrate 20. The substrate 20 is a light-transmitting substrate, and may be made of, for example, plastics such as PET (polyethylene terephthalate) and polyimide, or glass.

[0016] The first electrode 11 is formed on the substrate 20 as a transparent conductive film, and may be made of, for example, ITO, ZnO, FTO, SnO2, or the like. The first electrode 11 may be formed by a known method, such as sputtering, CVD, or vapor deposition. The first electrode 11 is cut (groove formation) for forming cells of the photoelectric conversion element 10 on the substrate 20 either before or after the electron transport layer 12 is formed. However, in FIG. 1, cut grooves and the like formed in the first electrode 11 are omitted for simplicity.

[0017] The electron transport layer 12 may be made of, for example, tin oxide, titanium oxide, zinc oxide, or the like. The thickness of the electron transport layer 12 may be, for example, 10 nm to 100 nm, but is not limited thereto. The electron transport layer 12 may be formed by a known method, for example, a sputtering method, a die coating method, a screen printing method, or the like. In this embodiment, the electron transport layer 12 is a dense layer, and is formed by using titanium oxide to form c (compact)-TiO2, applying a c-TiO2 precursor solution by spraying or spin coating, and baking at 450 to 500°C to form the electron transport layer 12.

[0018] In this disclosure, "dense" is also called "compact" or "compact," and means that, in cross-sectional observation, there are no light-absorbing regions (in this embodiment, a perovskite compound, and hereinafter described as a perovskite compound) on one side in the thickness direction of the dense material (for example, the lower side). In other words, even if there is a perovskite compound on the upper side of the dense material, it is possible to ensure that it does not penetrate through to the lower side of the dense material. Preferably, the dense material has extremely small voids. Preferably, the dense material has a maximum void width of less than 5 nm. Even more preferably, the dense material does not contain perovskite compounds in its voids, or does not have any regions where perovskite compounds exist continuously throughout the thickness of the dense material. That is, the dense material is sufficient if it can be seen by observation using SEM or EDX that there are no regions where perovskite compounds penetrate through the layer thickness. In this disclosure, unless otherwise specified, SEM observation is sufficient if it is observed and confirmed in a 400 nm wide cross-sectional SEM (or EDX) image. For example, if a single 400 nm wide cross-sectional SEM or EDX observation shows no areas where the perovskite compound penetrates the layer thickness, then that layer can be considered dense.

[0019] Figure 3 is a schematic cross-sectional view showing the process from the steps in Figure 2 to the formation of the pre-firing first porous layer 131' and the glass paste layer 15' on the electron transport layer 12. The pre-firing first porous layer 131' becomes the first porous layer 131, which is part of the photoelectric conversion layer 13, when fired. The glass paste layer 15' becomes the convex portion 15 when fired.

[0020] The pre-fired first porous layer 131' is formed by depositing a mixture of metal oxide microparticles 131a and a binder 131b such as resin using, for example, screen printing, die coating, gravure printing, etc. The glass paste layer 15' is formed by depositing a glass paste (powdered glass mixed with an organic binder and a solvent) using, for example, screen printing, die coating, gravure printing, etc. After depositing the pre-fired first porous layer 131' and the glass paste layer 15', the solvent is removed by temperature treatment at about 120°C.

[0021] The metal oxide particles 131a in the pre-baked first porous layer 131' may be, for example, titanium oxide, strontium titanate, etc. In this embodiment, titanium oxide is used as the metal oxide particles 131a, but the present invention is not limited thereto and the metal oxide particles 131a may contain at least one of titanium oxide and strontium titanate.

[0022] FIG. 4 is a schematic cross-sectional view showing the process up to the state where firing is performed after the process of FIG. 3. The firing here (first firing) is performed at a temperature of, for example, 500°C. This firing removes the binder 131b from the pre-fired first porous layer 131', and forms the first porous layer 131, which is an aggregate of metal oxide fine particles 131a. That is, the first porous layer 131 in this embodiment is formed as a layer of porous titanium oxide (m(mesoporous)-TiO2). The thickness of the first porous layer 131 may be, for example, 0.5 μm or more and 6 μm or less, but is not limited to this.

[0023] In this disclosure, "porous" is also called "porous" or "mesoporous," and can be the same as or include the same as these. Furthermore, "porous" means a material that can contain perovskite compounds in its voids. However, "porous" is not limited to a material that can contain perovskite compounds in its voids; it may also contain other materials with photoelectric conversion capabilities in its voids. Furthermore, in this disclosure, unless otherwise contradictory, "void or void in a member" means "a region in which a member is generally distributed dispersed or continuous, but where a member is absent." It is not limited to whether or not another member is formed in the void.

[0024] In addition, in the glass paste layer 15', the organic binder is removed by the first firing, and the powdered glass is baked and hardened, thereby forming the protrusions 15.

[0025] Figure 5 is a schematic cross-sectional view showing the process from the steps in Figure 4 to the formation of the pre-fired second porous layer 132' and the carbon paste layer 14' on the first porous layer 131. The pre-fired second porous layer 132' becomes the second porous layer 132, which is part of the photoelectric conversion layer 13, after firing. The carbon paste layer 14' is the pre-fired second electrode formed by depositing carbon paste, and becomes the second electrode 14 after firing.

[0026] The pre-firing second porous layer 132' is formed by depositing a mixture of metal oxide fine particles 132a and a binder 132b such as resin using, for example, a screen printing method, die coating method, or gravure printing method. After depositing the pre-firing second porous layer 132', the solvent is removed by heating at approximately 120°C (low-temperature firing). After solvent removal in the pre-firing second porous layer 132', the pre-firing carbon paste layer 14' is formed by depositing carbon paste (a mixture of powdered carbon, a binder such as resin, and a solvent) using, for example, a screen printing method, die coating method, or gravure printing method. After depositing the carbon paste layer 14', the solvent is removed by heating at approximately 120°C.

[0027] The metal oxide particles 132a in the pre-baked second porous layer 132' may be, for example, zirconium oxide, aluminum oxide, silicon oxide, etc. In this embodiment, zirconium oxide is used for the metal oxide particles 131a, but the present invention is not limited thereto and the metal oxide particles 131a may contain at least one of zirconium oxide, aluminum oxide, and silicon oxide.

[0028] FIG. 6 is a schematic cross-sectional view showing the process up to the state where firing is performed after the process of FIG. 5. The firing here (second firing) is performed at a temperature lower than the firing temperature in the first firing (the process of FIG. 4) (e.g., 400°C). More specifically, the firing temperature in the first firing is set to a temperature higher than the melting temperature of the powdered glass contained in the glass paste layer 15′, and the firing temperature in the second firing is set to a temperature lower than the melting temperature of the powdered glass. This firing removes the binder 132b from the pre-fired second porous layer 132′, and forms the second porous layer 132, which is an aggregate of metal oxide microparticles 132a. That is, the second porous layer 132 in this embodiment is formed as a layer of porous zirconium oxide (m (meso)-ZrO). The thickness of the second porous layer 132 is preferably 1.1 times or more the thickness of the first porous layer 131, more preferably 1.2 times or more, even more preferably 1.4 times or more, and even more preferably 2 times or more.

[0029] Furthermore, the binder is removed from the carbon paste layer 14' by the second firing, forming the second electrode 14, which is a carbon electrode. Since voids 141 are formed in the second electrode 14 where the binder was removed, the second electrode 14 becomes a porous carbon electrode. While the voids 141 in the second electrode 14 are depicted as discrete in FIG. 6 , in reality, the voids 141 in the second electrode 14 are continuously connected to each other in three dimensions, making the second electrode 14 a continuous porous body. Here, a continuous porous body refers to a body that can allow liquids to pass through in three dimensions. When observing the cross section of the second electrode 14, the voids 141 often appear discrete, but in some cases they may be continuously connected from top to bottom. The presence of discrete voids in the cross section can be considered to be the porous carbon electrode of this embodiment. Furthermore, the protrusions 15 are heat resistant to the firing temperature of the second firing. That is, the second firing does not generally cause any transformation of the protrusions 15.

[0030] In the final step, the perovskite precursor solution is dropped onto the internal region of the protrusion 15 from above the second electrode 14 and dried by heating at 50 to 60°C, thereby forming the perovskite compound 133 in the voids of the first porous layer 131 and the second porous layer 132. That is, in the final step, the dropped perovskite precursor solution is allowed to penetrate into the first porous layer 131 and the second porous layer 132 via the second electrode 14, and then the solvent is evaporated to form the perovskite compound 133. The photoelectric conversion element 10 in FIG. 1 is in a state after the final step has been completed.

[0031] 1, the photoelectric conversion layer 13 is composed of a first porous layer 131, a second porous layer 132, and a perovskite compound 133. The perovskite compound 133 in the photoelectric conversion layer 13 needs to be formed so as to be in reliable contact with the lower surface of the second electrode 14, and for this reason, the perovskite compound 133 may be formed even in part of the voids 141 of the second electrode 14.

[0032] When the perovskite precursor solution is dropped, the protrusions 15 function as a bank surrounding the periphery of the photoelectric conversion layer 13 and prevent the perovskite precursor solution from flowing out of the region of the photoelectric conversion layer 13 .

[0033] In this way, the protrusions 15 act as dikes for the perovskite precursor solution, so that in the photoelectric conversion element 10, the protrusions 15 come into contact with the outer periphery of the photoelectric conversion layer 13. In other words, the perovskite compound 133 in the photoelectric conversion layer 13 comes into contact with the protrusions 15. Therefore, in the photoelectric conversion element 10, the volume in which the perovskite precursor solution is formed is determined by the protrusions 15. Therefore, by dropping a predetermined amount of perovskite precursor solution, the perovskite compound 133 can be formed in the voids of the first porous layer 131 and the second porous layer 132 in a sufficient amount, without excess or deficiency. This allows the photoelectric conversion element 10 to achieve high conversion efficiency. Note that the protrusions 15 do not necessarily have to come into contact with the outer peripheries of the first porous layer 131 and the second porous layer 132 in the photoelectric conversion layer 13, or with the outer periphery of the second electrode 14.

[0034] Furthermore, the manufacturing procedure for the photoelectric conversion element 10 described with reference to Figures 2 to 6 and Figure 1 is merely an example, and the following modifications are also possible.

[0035] (Variation 1) The glass paste layer 15' may be formed before the electron transport layer 12 is formed (before the application of the c-TiO2 precursor solution and before firing). In this case, the glass paste layer 15' can be turned into the convex portions 15 by firing (firing at 450 to 500°C) to form the electron transport layer 12 (depending on the firing temperature of the glass paste layer 15'). Of course, the firing of the pre-firing first porous layer 131' can be referred to as the first firing, and the glass paste layer 15' can be turned into the convex portions 15. Furthermore, although the pre-firing second porous layer 132' is formed after the first firing in the above description, the pre-firing second porous layer 132' may be formed before the first firing.

[0036] (Variation 2) The glass paste layer 15' may be formed after the application of the c-TiO2 precursor solution (before the firing of c-TiO2) in forming the electron transport layer 12. In this case, the glass paste layer 15' can also be turned into the protrusions 15 by firing (firing at 450 to 500°C) to form the electron transport layer 12. The pre-firing second porous layer 132' may be formed before the first firing.

[0037] (Variation 3) The first firing may be performed after the pre-firing second porous layer 132' is formed. That is, the first firing may be performed after the pre-firing first porous layer 131', the pre-firing second porous layer 132', and the glass paste layer 15' are formed. If the firing temperature of the glass paste layer 15' is low, the first firing may be performed at a temperature of about 400 to 450°C. In this case, the pre-firing first porous layer 131' may be fired once at 500°C after it is formed.

[0038] That is, the manufacturing procedure for the photoelectric conversion element 10 basically includes the following steps 1 to 5. However, this procedure assumes that the first porous layer 131' is fired at 500°C and the carbon paste layer 14' is fired at 400°C. • First step: A step to form a glass paste layer 15'. • Second step: After the first step, the first firing is performed to make the glass paste layer 15' a convex portion 15. • Third step: A step in which a carbon paste layer 14' is formed after the second step. • Fourth step: A second firing is performed after the third step, and the carbon paste layer 14' is used as the second electrode 14. Fifth step: after the fourth step, a perovskite precursor solution is dropped to form a perovskite compound 133 in the voids of the first porous layer 131 and the second porous layer 132.

[0039] The first porous layer 131' and the second porous layer 132' before firing may undergo either the first firing or the second firing in order to become the first porous layer 131 and the second porous layer 132 (for binder removal). That is, the deposition of the first porous layer 131' before firing may be carried out in either the first or third step. The deposition of the second porous layer 132' before firing may be carried out in either the first or third step, as long as it is after the deposition of the first porous layer 131' before firing. Furthermore, when the deposition of the first porous layer 131' and the second porous layer 132' before firing is carried out in the first step, the deposition order of the glass paste layer 15' and the deposition of the first porous layer 131' and the second porous layer 132' before firing is not particularly limited.

[0040] Furthermore, the reason why the carbon paste layer 14' is fired at 400°C in the above procedure is that if the firing temperature is too high, there is a concern that the carbon will disappear. However, there is a possibility that the carbon will not disappear (or will only disappear slightly) even at 500°C, in which case it is considered possible to perform firing of the first porous layer 131' before firing, the second porous layer 132' before firing, the carbon paste layer 14' and the glass paste layer 15' in a single firing after the formation of the carbon paste layer 14', without separating the first and second firings. In other words, the manufacturing procedure in this case includes the following steps 1 to 4. • First step: A step to form a glass paste layer 15'. Second step: a step of depositing a carbon paste layer 14' after the first step. Third step: A step of firing after the second step to form the glass paste layer 15' into the protrusions 15 and the carbon paste layer 14' into the second electrode 14. • Step 4: After Step 3, a perovskite precursor solution is added dropwise to form a perovskite compound 133 in the voids of the first porous layer 131 and the second porous layer 132.

[0041] As a further modification, the second electrode 14 may be a transparent electrode such as ITO instead of the carbon electrode described above. However, in this case, the second electrode 14 also needs to be a porous layer to allow the perovskite precursor solution dropped in step 5 to pass through. After forming a film from a paste made by mixing an electrode material that will become the transparent electrode with a binder, firing (second firing) is required to remove the binder. Therefore, even when the second electrode 14 is a transparent electrode such as ITO, the manufacturing procedure for the photoelectric conversion element 10 is the same as when the second electrode 14 is a carbon electrode.

[0042] Other examples of materials for the second electrode 14 include metals such as Ni, Pt, and Pd. A porous layer can be formed using metal fine particles. The thickness of the second electrode 14 is preferably about 50 nm to 150 nm. The second electrode 14 can be made of conductive materials such as graphite, graphene, carbon nanowires, carbon nanofibers, carbon nanotubes, and carbon black. Basically, any material that is conductive is not excluded from application.

[0043] In the present disclosure, the protrusions 15 are described as being provided on the first electrode 11 and the electron transport layer 12, but they do not necessarily have to be provided on the first electrode 11 and the electron transport layer 12, and depending on the structure of the photoelectric conversion element, they may have the reverse structure (provided on the second electrode and the hole transport layer) or may be provided on the substrate 20. However, providing the protrusions 15 on the first electrode 11 and the electron transport layer 12 is more desirable in terms of the manufacturing process and the element configuration.

[0044] Second Embodiment In the first embodiment, the perovskite precursor solution is dropped after the second electrode 14 is formed. In the present embodiment, a photoelectric conversion element 10 is described that is manufactured by dropping the perovskite precursor solution before the second electrode 14 is formed. An example of a manufacturing procedure for the photoelectric conversion element 10 is described below with reference to FIGS. 7 to 10.

[0045] 7 is a schematic cross-sectional view showing the steps of forming the first electrode 11, the electron transport layer 12, the first porous layer 131, and the second porous layer 132 on the substrate 20. Each of these layers has the same configuration as in the first embodiment and can be formed by the same method. That is, the first porous layer 131 and the second porous layer 132 are formed by forming the pre-fired first porous layer 131′ and the pre-fired second porous layer 132′ and then firing them.

[0046] Figure 8 is a schematic cross-sectional view showing the process from the step in Figure 7 to the formation of the protrusions 15 on the electron transport layer 12. The protrusions 15 in this embodiment can be made of resin and are formed by film deposition using methods such as screen printing, die coating, or gravure printing.

[0047] 9 is a schematic cross-sectional view showing the process up to the formation of the perovskite compound 133 after the process of FIG. 8. In this process, a perovskite precursor solution is dropped onto the internal regions of the convex portions 15 from above the first porous layer 131 and the second porous layer 132, and dried by heating at 50 to 60°C, thereby forming the perovskite compound 133 in the voids of the first porous layer 131 and the second porous layer 132. In this way, a photoelectric conversion layer 13 consisting of the first porous layer 131, the second porous layer 132, and the perovskite compound 133 is formed.

[0048] FIG. 10 is a schematic cross-sectional view showing the process up to the formation of the second electrode 14 after the process of FIG. 9. The second electrode 14 of this embodiment does not need to be a porous layer because it does not need to pass a perovskite precursor solution through it. For this reason, the second electrode 14 is preferably formed of a transparent electrode film such as ITO. In this embodiment, since the second electrode 14 is not a porous layer, binder removal (to form voids in the second electrode 14) is not required, and firing for binder removal (second firing) is also not required. Therefore, the protrusions 15 do not need to be heat resistant to the second firing, and can be made of resin. The photoelectric conversion element 10 of this embodiment is completed by forming the second electrode 14.

[0049] In the photoelectric conversion element 10 of this embodiment, when the perovskite precursor solution is dropped, the protrusions 15 function as a barrier surrounding the photoelectric conversion layer 13, preventing the perovskite precursor solution from flowing out of the area of ​​the photoelectric conversion layer 13. Since the protrusions 15 are in contact with the perovskite compound 133 in the photoelectric conversion layer 13, dropping a predetermined amount of perovskite precursor solution allows for the complete and complete formation of the perovskite compound 133 in the voids of the first porous layer 131 and the second porous layer 132. As a result, high conversion efficiency can be obtained in the photoelectric conversion element 10.

[0050] Third Embodiment Fig. 11 is a plan view of a photoelectric conversion element 10 having a single cell structure, and Fig. 12 is a plan view of a photoelectric conversion element 10 having a multiple cell structure.

[0051] As shown in Figure 11, in the single-cell photoelectric conversion element 10, one cell S is formed on the substrate 20. The cell S represents the laminated structure portion of the first electrode 11, electron transport layer 12, photoelectric conversion layer 13, and second electrode 14. In the single-cell photoelectric conversion element 10, a protrusion 15 is formed so as to surround the entire outer circumference of one cell S.

[0052] On the other hand, as shown in Figure 12, in the photoelectric conversion element 10 with a multi-cell structure, a plurality of cells S are formed on the substrate 20. The plurality of cells S are formed along a predetermined arrangement direction and are connected in series within the element. In such a multi-cell structure, if the gap g between adjacent cells S is sufficiently small, the protrusion 15 may be formed so as to surround the plurality of cells S with a single protrusion 15. That is, the protrusion 15 may be formed so as to be in contact with each cell S only on the sides other than the side facing another cell S (the side that forms the gap g). Here, if the gap g is sufficiently small, for example, if the gap g corresponds to the gap separating the second electrode 14 (for example, the width of P3), then the gap g is approximately 0.5 mm or less and approximately 0.1 mm or more. Furthermore, if the gap g includes the gap separating the first electrode 11 (e.g., the width of P1), the gap separating the porous titanium oxide (i.e., the first porous layer 131) or porous zirconium oxide (i.e., the second porous layer 132) (e.g., the width of P2), and the width of P3, that is, if it corresponds to the maximum width from P1 to P3 in the portion where P1, P2, and P3 are continuously provided, then this refers to the case where the gap g is approximately 1 mm or less and approximately 0.2 mm or more.

[0053] In the multi-cell photoelectric conversion element 10, when the perovskite precursor solution is dropped, some of the perovskite precursor solution flows out into the gap g. However, the amount of outflow is small and does not flow outside the photoelectric conversion element 10, so there is no shortage in the formation of the perovskite compound 133. As a result, high conversion efficiency can be obtained in the photoelectric conversion element 10 by forming the convex portion 15 as shown in Figure 12.

[0054] In the embodiments of this disclosure, the projection 15 and the perovskite compound 133 are shown in a schematic cross-sectional view in an ideal manner, with all contact surfaces and contact extending to the same height. However, the illustration is a schematic diagram, and it is not necessarily required that all contact surfaces be in contact, nor that contact extend to the same height. The manner and height of formation of the perovskite compound 133 by the coating and firing processes of the perovskite precursor solution can be changed in various ways and are not limited thereto. That is, depending on the cross-section, the projection 15 and the perovskite compound 133 may be formed in a manner in which they are in contact only in part by the coating and drying processes. Generally, they are in contact along the entire height of the perovskite compound 133, but depending on how they are formed by the coating and drying processes, there may be parts that are not in contact. Therefore, if it can be confirmed in cross-sectional observation that at least a portion of the protrusion 15 and the perovskite compound 133 are in contact with the cross-section, then it can be said that this constitutes contact between the protrusion 15 and the perovskite compound 133 as described in this disclosure. Furthermore, it is desirable that, in cross-sectional observation, the protrusion 15 and the perovskite compound 133 are in contact with approximately the entire height of the perovskite compound 133. It is also desirable that the protrusion 15 and the perovskite compound 133 are in contact up to approximately the same height at two contact points in the cross-section.

[0055] [Fourth embodiment] Perovskite solar cells experience performance degradation when the photoelectric conversion layer is exposed to the outside air, moisture, etc. Therefore, it is necessary to encapsulate the photoelectric conversion layer. Figure 13 is a cross-sectional view showing a schematic configuration of an example of a photoelectric conversion module 100 in which the photoelectric conversion element 10 has been encapsulated.

[0056] The photoelectric conversion module 100 uses the above-described substrate 20 as the first substrate 20, and further adds a second substrate 21 and a sealing portion 22 to seal at least the portion of the photoelectric conversion element 10 sandwiched by the protrusions 15 (in this disclosure, unless otherwise specified, the description of the sealed photoelectric conversion element refers to at least the portion sandwiched by the protrusions 15). Specifically, the photoelectric conversion module 100 has a photoelectric conversion element 10 placed between the second substrate 21 and the first substrate 20, and a sealing portion 22 formed between the second substrate 21 and the first substrate 20 to surround the photoelectric conversion element 10. The sealing portion 22 is formed to be in close contact with the second substrate 21. A first electrode 11 and an electron transport layer 12 may be present between the sealing portion 22 and the first substrate 20, in which case the sealing portion 22 is formed to be in close contact with the electron transport layer 12. The sealing portion 22 is preferably made of a material with high sealing performance (that does not allow water vapor, etc. to pass through), and for example, UV-curing resin, thermosetting resin, polyisobutylene, etc. can be used.

[0057] In the photoelectric conversion module 100, the photoelectric conversion element 10 (at least the photoelectric conversion layer 13) is sealed within a sealed space formed by the second substrate 21, the first substrate 20, and the sealing portion 22. This prevents the photoelectric conversion module 100 from experiencing performance degradation due to exposure of the photoelectric conversion layer 13 of the photoelectric conversion element 10 to outside air, moisture, etc.

[0058] In the example shown in Figure 13, the sealing portion 22 is spaced apart from the photoelectric conversion element 10, but it is not necessarily required that they be spaced apart. The sealing portion 22 is optimally formed according to the sealing performance or the requirements of the manufacturing process.

[0059] Furthermore, the sealing structure in the photoelectric conversion module 100 is not limited to the example in Figure 13, but may also be as shown in Figures 14 to 16, for example.

[0060] In the example shown in Figure 14, the photoelectric conversion element 10 (at least the photoelectric conversion layer 13) is sealed with a sealing resin (sealing part) 23 instead of the sealing part 22. In this case, the sealing resin 23 is formed by potting resin on the first substrate 20 and is provided so as to be in close contact with the photoelectric conversion element 10. If sufficient sealing of the photoelectric conversion layer 13 can be obtained by such a sealing resin 23, the sealing part 22 in Figure 13 can be omitted.

[0061] The examples in Figures 15 and 16 show a structure in which a sealing portion 22 and a sealing resin 23 are used in combination to further enhance the sealing function of the photoelectric conversion layer 13. That is, the photoelectric conversion element 10 (at least the photoelectric conversion layer 13) is sealed with a sealing resin 23, and then a sealing portion 22 is provided on its outer circumference. In this case, the sealing resin 23 may be in close contact with the sealing portion 22 (Figure 15), or it may not be in close contact with the sealing portion 22 (Figure 16). As for the manufacturing method, it is preferable not to make the sealing resin 23 in close contact with the sealing portion 22, as shown in Figure 16.

[0062] Furthermore, the sealing portion 22 may be made of a resin material. Alternatively, the sealing portion 22 may be made of the same material as the protrusion portion 15. Also, the sealing portion 22 may be made of the same glass material as the protrusion portion 15.

[0063] In this disclosure, unless otherwise specified, the term "layer" or "film" does not necessarily mean that the thickness or width is constant, but also includes those with varying thicknesses, or those that are patterned or island-shaped. Preferably, the layer or film has a substantially constant thickness.

[0064] Furthermore, unless otherwise specified, in this disclosure, "approximately," "generally," or "to a certain extent" means a range of manufacturing tolerances, preferably indicating a tolerance of plus 15% and minus 15% of that value.

[0065] The perovskite compound is composed of a compound represented by the general formula: ABX3···(1). However, the composition ratio of each is preferably 1:1:3, but it is not necessarily 1:1:3, the content of each element may be raised or lowered as appropriate, and each constituent element does not need to be of only one type, and as long as the solar cell has a photoelectric conversion function, it has the degree of freedom of composition as described. In general formula (1), A is an organic molecule (including an organic group or an organic cation, as is the case in this disclosure) or an inorganic atom or molecule (including an inorganic group or an inorganic cation, as is the case in this disclosure) or a combination thereof, B is a metal atom or molecule (including a metal cation, as is the case in this disclosure), and X is a halogen atom or molecule or a chalcogen atom or molecule (including a halogen anion or a chalcogen anion, as is the case in this disclosure). In general formula (1), the three Xs may be the same or different from each other. Perovskite compounds, by being contained in a light-absorbing layer, can absorb light and convert it into electricity, and this should be taken into consideration. In other words, it is sufficient to know that a compound is a perovskite compound if it contains, for example, organic molecules, metal atoms, and halogen atoms. Furthermore, it is sufficient to know that a compound is a perovskite compound if elements corresponding to A, B, and X are detected, insofar as the solar cell has a photoelectric conversion function. For example, molecules containing carbon, nitrogen, and hydrogen are suitable as organic molecules, and therefore, it is sufficient to know that carbon, nitrogen, hydrogen, metal elements, and halogen elements or chalcogen elements are detected. Alternatively, it is sufficient to know that a compound is a perovskite compound if it contains A, B, and X, for example, if it contains inorganic atoms, metal atoms, and halogen atoms. Furthermore, it is sufficient to know that a compound is a perovskite compound if elements corresponding to A, B, and X are detected, insofar as the solar cell has a photoelectric conversion function. For example, cesium or rubidium are suitable as inorganic atoms, and therefore, it is sufficient to know that cesium or rubidium, metal elements, and halogens or chalcogens are detected. Furthermore, it is not necessary to confirm that a compound is a perovskite compound, since it is a natural consequence that a solar cell must have a crystalline structure in order to have a photoelectric conversion function.The light-absorbing layer may contain compounds other than perovskite compounds.

[0066] Furthermore, the light-absorbing layer may contain organic-inorganic hybrid compounds. An organic-inorganic hybrid compound means a compound that contains both inorganic and organic elements. Perovskite compounds are included in organic-inorganic hybrid compounds. Organic typically refers to materials composed of multiple carbon elements. However, carbon materials such as graphite, graphene, carbon nanowires, carbon nanofibers, carbon nanotubes, and carbon or carbon black that function as electrodes are not specifically considered organic. In other words, organic refers to materials that, excluding the aforementioned carbon materials such as graphite, have multiple carbon elements as one of their constituent elements. Inorganic means materials that are not organic.

[0067] A light-absorbing layer is a layer capable of absorbing light. In this disclosure, a perovskite compound is used as an example. This layer absorbs light incident on the photoelectric conversion layer and generates electrons and holes. These electrons move to the electron transport layer, and the holes move to the hole transport layer. The fact that a light-absorbing layer absorbs light and generates electrons and holes is self-evident as long as the solar cell functions as a solar cell and does not require verification. As long as the material containing the function of light absorption is included, it can be assumed that the light-absorbing layer absorbs light and generates electrons and holes.

[0068] A light-absorbing region can refer to any part of a material that absorbs light (for example, a perovsky compound). If there are other light-absorbing regions besides the indicated light-absorbing region, they can be collectively described as a light-absorbing layer. In other words, a light-absorbing region can mean any part of a light-absorbing layer. Furthermore, a light-absorbing layer can refer to a collection of light-absorbing regions that exist discretely or continuously in a region that is mainly in a certain direction and has a thickness (similar to the definition of a "layer," it does not need to be constant, for example).

[0069] The embodiments disclosed herein are illustrative in all respects and are not intended to be restrictive. Therefore, the technical scope of this disclosure is not to be interpreted solely by the embodiments described above, but is determined by the claims.

[0070] [Note]

[0071] (Aspect 1) A first electrode and a second electrode, a photoelectric conversion layer provided between the first electrode and the second electrode; a convex portion formed so as to surround the periphery of the photoelectric conversion layer, the photoelectric conversion layer includes a porous layer and a perovskite compound formed in pores of the porous layer, The photoelectric conversion element is characterized in that the convex portion is in contact with the perovskite compound.

[0072] (Aspect 2) The photoelectric conversion element according to aspect 1, the second electrode is formed of a continuous porous body, The photoelectric conversion element is characterized in that the convex portion is made of glass.

[0073] (Aspect 3) The photoelectric conversion element according to aspect 2, The photoelectric conversion element is characterized in that the second electrode is a porous carbon electrode.

[0074] (Aspect 4) The first substrate and a photoelectric conversion element formed on the first base material; a second base material for disposing the photoelectric conversion element between the first base material and the second base material; a sealing portion that seals the photoelectric conversion layer of the photoelectric conversion element between the first base material and the second base material, A photoelectric conversion module, wherein the photoelectric conversion element is the photoelectric conversion element according to any one of aspects 1 to 3.

[0075] (Aspect 5) A method for producing the photoelectric conversion element according to any one of Aspects 1 to 3, comprising: A step of forming the first electrode and the porous layer of the photoelectric conversion layer on the first substrate, A step of forming the protrusions on the first substrate so as to surround the porous layer, and dropping a precursor solution of a perovskite compound onto an internal region of the convex portion to allow it to penetrate into the porous layer, and drying the penetrated precursor solution of the perovskite compound to form the perovskite compound.

[0076] (Aspect 6) A method for manufacturing a photoelectric conversion element according to aspect 2 or 3, A first step involves forming a glass paste layer containing powdered glass and a binder on a first substrate on which the first electrode is formed, A second step is performed after the first step, in which a first firing is carried out to make the glass paste layer the protrusion, A third step is performed to form a pre-firing second electrode, which consists of a paste made by mixing electrode material and binder, after the second step described above. A fourth step is performed after the third step, in which a second firing is carried out, and the second electrode before firing is made into the second electrode, a fifth step, after the fourth step, of dropping a perovskite precursor solution into the internal regions of the convex portions to allow it to penetrate into the porous layer, and drying the perovskite compound precursor solution that has penetrated, thereby forming the perovskite compound.

[0077] (Aspect 7) A method for manufacturing a photoelectric conversion element according to aspect 2 or 3, A first step involves forming a glass paste layer containing powdered glass and a binder on a first substrate on which the first electrode is formed, A second step is performed after the first step, in which a second electrode, which is a paste made by mixing electrode material and binder, is formed before firing. A third step is performed in which firing is carried out after the second step, the glass paste layer becomes the protrusion, and the pre-firing second electrode becomes the second electrode, and a fourth step, after the third step, of dropping a perovskite precursor solution into the internal regions of the convex portions to allow it to penetrate into the porous layer, and drying the perovskite compound precursor solution that has penetrated, thereby forming the perovskite compound. [Explanation of symbols]

[0078] 10 Photoelectric conversion element 11 1st electrode 12 Electron transport layer 13 Photoelectric conversion layer 131 First porous layer 131' First porous layer before firing 131a Metal oxide fine particles 131b Binder 132 Second porous layer 132' Pre-fired second porous layer 132a Metal oxide fine particles 132b Binder 133 Perovskite Compounds 14 2nd electrode 14' Carbon paste layer (second electrode before firing) 141 void 15 Convex part 15' Glass paste layer 20 Base material (1st base material) 21 Second base material 22 Sealing part 23 Sealing resin (sealing part) 100 Photoelectric conversion module S Cell

Claims

1. a first electrode and a second electrode; a photoelectric conversion layer provided between the first electrode and the second electrode; a convex portion formed so as to surround the periphery of the photoelectric conversion layer, the photoelectric conversion layer includes a porous layer and a perovskite compound formed in pores of the porous layer, The photoelectric conversion element is characterized in that the convex portion is in contact with the perovskite compound.

2. The photoelectric conversion element according to claim 1, the second electrode is formed of a continuous porous body, The photoelectric conversion element is characterized in that the convex portion is made of glass.

3. The photoelectric conversion element according to claim 2, The photoelectric conversion element is characterized in that the second electrode is a porous carbon electrode.

4. A first substrate; a photoelectric conversion element formed on the first substrate; a second substrate for disposing the photoelectric conversion element between the first substrate and the second substrate; a sealing portion that seals the photoelectric conversion layer of the photoelectric conversion element between the first base material and the second base material, A photoelectric conversion module, wherein the photoelectric conversion element is the photoelectric conversion element according to claim 1 .

5. A method for manufacturing the photoelectric conversion element according to claim 1, forming the first electrode and the porous layer of the photoelectric conversion layer on a first substrate; forming the convex portion on the first substrate so as to surround the periphery of the porous layer; and dropping a precursor solution of a perovskite compound onto an internal region of the convex portion to allow it to penetrate into the porous layer, and drying the penetrated precursor solution of the perovskite compound to form the perovskite compound.

6. A method for manufacturing a photoelectric conversion element according to claim 2, a first step of forming a glass paste layer containing powdered glass and a binder on a first substrate on which the first electrode is formed; a second step of performing a first firing after the first step to form the glass paste layer into the convex portions; a third step of forming a pre-fired second electrode made of a paste obtained by mixing an electrode material and a binder after the second step; a fourth step of performing a second firing after the third step to convert the pre-fired second electrode into a second electrode; and a fifth step, after the fourth step, of dropping a perovskite precursor solution into an internal region of the convex portion to allow it to penetrate into the porous layer, and drying the penetrated precursor solution of the perovskite compound to form the perovskite compound.

7. A method for manufacturing a photoelectric conversion element according to claim 2, a first step of forming a glass paste layer containing powdered glass and a binder on a first substrate on which the first electrode is formed; a second step of forming a pre-fired second electrode made of a paste obtained by mixing an electrode material and a binder after the first step; a third step of firing the glass paste layer after the second step to form the convex portion and the pre-fired second electrode as a second electrode; and a fourth step, after the third step, of dropping a perovskite precursor solution into an internal region of the convex portion to allow it to penetrate into the porous layer, and drying the penetrated precursor solution of the perovskite compound to form the perovskite compound.

Images