JP6849673B2 - Solid-state junction type photoelectric conversion element and its manufacturing method - Google Patents

Description

The present invention relates to a solid-state junction type photoelectric conversion element and a method for manufacturing the same. The present application claims priority based on Japanese Patent Application No. 2016-098417 filed in Japan on May 17, 2016, the contents of which are incorporated herein by reference.

In recent years, it has been reported that a solid-bonded photoelectric conversion element provided with a power generation layer containing a perovskite compound exhibits high photoelectric conversion efficiency (Non-Patent Document 1), and is attracting attention as a new photoelectric conversion element. Starting with this report, further improvements in photoelectric conversion efficiency have been reported one after another (for example, Non-Patent Document 2).

“Efficient Hybrid Solar Cells Based on Meso-Superstructured Organometal Halide Perovskites” Science, 2012, 338, p643-647. “Solvent engineering for high-performance inorganic-organic hybrid perovskite solar cells” Nature Materials 2014, 13, p897-903.

When the present inventors examined the manufacturing yield from the viewpoint of putting the above-mentioned solid-state junction type photoelectric conversion element into practical use, they encountered a problem that a leakage current is likely to occur in the conventional manufacturing method and a large number of defective products are generated. ..

The present invention has been made in view of the above circumstances, and provides a solid-state junction type photoelectric conversion element having a structure in which a leak current is unlikely to occur, and a method for manufacturing the same.

When the present inventors investigated the cause of the above-mentioned leak current, it was found that pinholes and / or cracks were generated in the perovskite layer. Therefore, it is considered that the first conductive layer side and the second conductive layer side sandwiching the perovskite layer are short-circuited through pinholes and cracks, and a leak current is generated. As a mechanism for generating pinholes and cracks, in the manufacturing process of a solid-bonded photoelectric conversion element, a solution containing a perovskite compound is applied to a conductive support layer (adjacent layer described later), and a solvent contained in the coating film is applied. It was considered that pinholes and cracks were generated when the solvent was dried and crystallized.
Therefore, as a result of diligent studies on a manufacturing process that suppresses the occurrence of pinholes and cracks during drying, it was found that the purpose can be achieved by roughening the surface roughness of the support layer to which the solution of the perovskite compound is applied. The present invention has been completed. The present invention is as follows.

[1] A solid-bonded photoelectric conversion element having a first conductive layer, a perovskite layer, and a second conductive layer in this order, and at least one adjacent layer among two adjacent layers adjacent to both sides of the perovskite layer. The maximum height roughness (Rz) of the joint surface in contact with the perovskite layer is 1 nm or more, and the Rz is the maximum peak height (Rp) and valley depth within the reference length (L) of the joint surface. A solid-state junction type photoelectric conversion element which is the sum of the maximum values (Rv).
[2] Of the area S (= L × Rz) of a quadrangle having the reference length (L) as the horizontal side and the Rz as the vertical side in a cross-sectional view including the joint surface in the thickness direction, the said The solid-state junction type photoelectric conversion element according to [1], wherein the occupancy of the adjacent layer is 10 to 90%.
[3] The solid-state junction type photoelectric conversion element according to [1] or [2], wherein the first conductive layer is an adjacent layer having an Rz of 1 nm or more.
[4] The method according to [1] or [2], wherein an anchor layer containing fine particles is provided between the first conductive layer and the perovskite layer, and the anchor layer is an adjacent layer having an Rz of 1 nm or more. Solid-state junction type photoelectric conversion element.
[5] An N-type semiconductor layer is provided between the first conductive layer and the perovskite layer, and the N-type semiconductor layer is an adjacent layer having an Rz of 1 nm or more, according to [1] or [2]. The solid-state junction type photoelectric conversion element described.
[6] An N-type semiconductor layer and an anchor layer containing fine particles are provided in this order between the first conductive layer and the perovskite layer, and the anchor layer is an adjacent layer having an Rz of 1 nm or more. The solid-state junction type photoelectric conversion element according to 1] or [2].
[7] An N-type semiconductor layer is provided between the first conductive layer and the perovskite layer, the N-type semiconductor layer is an adjacent layer having an Rz of 1 nm or more, and the N-type semiconductor layer is combined with the first. The maximum height roughness (Rz') of the joint surface in which one conductive layer is adjacent and is in contact with the N-type semiconductor layer in the first conductive layer is 1 nm or more, and the Rz'is the said in the first conductive layer. The solid-state junction type photoelectric conversion element according to [1] or [2], which is the sum of the maximum peak height (Rp) and the maximum valley depth (Rv) within the reference length (L) on the junction surface.
[8] The P-type semiconductor layer is provided between the perovskite layer and the second conductive layer, and the P-type semiconductor layer is an adjacent layer having an Rz of 1 nm or more, according to [1] to [7]. The solid-state junction type photoelectric conversion element according to any one item.
[9] A base material in contact with the surface of the first conductive layer opposite to the perovskite layer is provided, and the maximum height roughness (Rz ") of the joint surface of the base material in contact with the first conductive layer is 1 nm. As described above, the Rz ”is the sum of the maximum peak height (Rp) and the maximum valley depth (Rv) within the reference length (L) at the joint surface of the base material, [1] to The solid-state junction type photoelectric conversion element according to any one of [8].
[10] The Rz (Rz-a) in the adjacent layer on the first conductive layer side and the Rz (Rz-b) in the adjacent layer on the second conductive layer side are 1 nm or more, and the above (Rz). -a) / The solid-state junction type photoelectric conversion element according to any one of [1] to [9], wherein the roughness ratio represented by (Rz-b) is 0.1 or more and 1000 or less.
[11] A method for manufacturing a solid-state bonding photoelectric conversion element including a perovskite layer and an adjacent layer having a bonding surface in contact with the perovskite layer, wherein the perovskite layer is formed on the bonding surface of the adjacent layer. It has a step of applying a solution containing the above to form a coating film and a step of forming the perovskite layer by drying the coating film, and the maximum height roughness (Rz) of the joint surface is 1 nm. As described above, the Rz is the sum of the maximum peak height (Rp) and the maximum valley depth (Rv) within the reference length (L) at the junction surface, and is a method for manufacturing a solid junction photoelectric conversion element. ..
[12] The method for producing a solid-bonded photoelectric conversion element according to [11], wherein the coating film is dried by blowing warm air at 40 to 60 ° C. to form the perovskite layer.
[13] Production of the solid-bonded photoelectric conversion element according to [11] or [12], wherein the coating film is dried after dropping a poor solvent for the compound onto the coating film to form the perovskite layer. Method.

In the solid-state bonding photoelectric conversion element of the present invention, the bonding area between the perovskite layer and the adjacent layer is increased because the bonding surface of the adjacent layer bonded to the perovskite layer has a specific roughness. With this structure, not only the generation of cracks that may occur during manufacturing but also the generation of cracks that may occur due to bending or strain during use can be suppressed, and the generation of leakage current can be reduced.
According to the method for manufacturing a solid-state junction type photoelectric conversion element of the present invention, it is possible to suppress the occurrence of pinholes and cracks in the perovskite layer formed on the adjacent layer, so that the solid-bonded photoelectric conversion element in which leakage current is unlikely to occur is unlikely to occur. The conversion element can be easily manufactured.

It is sectional drawing of the 1st Embodiment of the solid-state junction type photoelectric conversion element of this invention. It is sectional drawing of the 2nd Embodiment of the solid-state junction type photoelectric conversion element of this invention. It is sectional drawing of the 3rd Embodiment of the solid-state junction type photoelectric conversion element of this invention. It is sectional drawing of the 4th Embodiment of the solid-state junction type photoelectric conversion element of this invention. It is sectional drawing of the 5th Embodiment of the solid-state junction type photoelectric conversion element of this invention. It is sectional drawing of the sixth embodiment of the solid-state junction type photoelectric conversion element of this invention. It is sectional drawing of the 7th Embodiment of the solid-state junction type photoelectric conversion element of this invention. It is sectional drawing which shows the boundary between the perovskite layer and the adjacent layer in an example of the solid-state junction type photoelectric conversion element of this invention. It is sectional drawing which shows the boundary between the perovskite layer and the adjacent layer in an example of the solid-state junction type photoelectric conversion element of this invention. It is a graph which shows the relationship between Rz (Rz-a) of the solid-state junction type photoelectric conversion element produced in an Example, and the occurrence frequency of a leakage current. It is a graph which shows the relationship between the roughness ratio of Rz-a / Rz-b of the solid-state junction type photoelectric conversion element produced in an Example, and the photoelectric conversion efficiency.

Hereinafter, the present invention will be described with reference to the drawings based on the preferred embodiments, but the present invention is not limited to such embodiments.

In the present specification, "membrane" and "layer" are not distinguished unless otherwise specified. A solid-bonded photoelectric conversion element may be simply referred to as a "photoelectric conversion element", and an organic-inorganic perovskite compound may be simply referred to as a "perovskite compound".

<< Solid-state junction type photoelectric conversion element >>
The solid-state bonded photoelectric conversion element according to the first aspect of the present invention is a solid-bonded photoelectric conversion element including a first conductive layer, a perovskite layer, and a second conductive layer in this order.
Another layer such as an anchor layer containing fine particles or an N-type semiconductor layer may be provided between the first conductive layer and the perovskite layer. The adjacent layer (first adjacent layer) adjacent to the perovskite layer on the first conductive layer side may be the first conductive layer or the other layer. The first conductive layer can function as an anode (an electrode through which electrons flow out to an external circuit).
Another layer such as an anchor layer containing fine particles or a P-type semiconductor layer may be provided between the perovskite layer and the second conductive layer. The adjacent layer (second adjacent layer) adjacent to the perovskite layer on the second conductive layer side may be the second conductive layer or the other layer. The second conductive layer can function as a cathode (an electrode through which electrons flow from an external circuit).

The solid-state junction type photoelectric conversion element of the first aspect of the present invention includes at least a first conductive layer, a perovskite layer, and a second conductive layer in this order, and further, an N-type between the first conductive layer and the perovskite layer. At least one of a semiconductor layer and an anchor layer is optionally provided, and a P-type semiconductor layer is optionally provided between the second conductive layer and the perovskite layer. The first conductive layer, the N-type semiconductor layer, or the anchor layer is directly laminated on the first surface of the perovskite layer, and the second conductive layer or the P is on the second surface of the perovskite layer. The type semiconductor layer is directly laminated. Directly laminated on the first adjacent layer (the first conductive layer, the N-type semiconductor layer or the anchor layer) directly laminated on the first surface of the perovskite layer and the second surface of the perovskite layer. The maximum height roughness (Rz) of the bonding surface in contact with the perovskite layer in at least one of the second adjacent layers (the second conductive layer or the P-type semiconductor layer) is 1 nm or more. Here, Rz is the sum of Rp and Rv, as will be described later.

The perovskite layer is a layer formed by crystallizing or solidifying a perovskite compound, and is preferably a layer mainly made of a perovskite compound except for trace substances that can be doped.

FIG. 8 illustrates a partial cross-sectional view of the photoelectric conversion element according to the present invention in the thickness direction. In this cross section, the boundary line between the perovskite layer and the arbitrary adjacent layer is a line that traces the fracture surface of the joint surface K between the perovskite layer and the arbitrary adjacent layer.

In the photoelectric conversion element according to the present invention, as illustrated in FIG. 8, the perovskite in at least one of the two adjacent layers (first adjacent layer and second adjacent layer) adjacent to both sides of the perovskite layer. The maximum height roughness (Rz) of the joint surface K in contact with the layer is 1 nm or more.
Here, Rz is the sum of the maximum mountain height (Rp) and the maximum valley depth (Rv) within the reference length (L) at the joint surface K. This Rz is synonymous with the maximum height roughness (Rz) specified in JIS B0601-2001 (ISO 4287: 1997), and is measured as follows in accordance with the standard. The reference length (L) is arbitrarily set in the range of, for example, 1 μm or more and 10 μm or less, but when a large crack is generated in the perovskite layer, the reference length is measured so as to measure the region excluding the crack. Set (L). Further, the reference length (L) may be appropriately set according to the crystal size of the perovskite compound, as long as the Rz at a plurality of locations can be measured (for example, 5 locations).
As a specific measurement method of Rz, the cross section cut in the thickness direction of the solid-state junction type photoelectric conversion element to be measured is observed with a scanning electron microscope, the junction surface K is specified by image processing, and the above Rz is measured. The lengthening method is preferred. It is preferable to measure Rz at a plurality of points (for example, 5 points) for the same measurement target and set the arithmetic mean as Rz.

When the Rz of the joint surface K is 1 nm or more, it is possible to prevent the residual stress contained in the perovskite layer from being released when the photoelectric conversion element is used and causing pinholes and cracks.
As this mechanism, by making the adjacent layers bite into the perovskite layer at a plurality of places, the residual stress inside the perovskite layer prevents slipping in the direction away from each other (direction along the joint surface K). Conceivable. Further, it is considered that the portion where the residual stress is concentrated, which leads to the slippage, is reduced, or the residual stress inside the perovskite layer is dispersed.
It is conceivable that the above-mentioned residual stress may occur when a solution containing a perovskite compound is applied and dried at the time of manufacturing the photoelectric conversion element to form a coating film, or after the coating film is formed.

When the Rz of the joint surface K is 1 nm or more, the joint area (surface area of the adjacent layer) between the perovskite layer and the adjacent layer increases as compared with the case where the Rz is less than 1 nm. As a result, the efficiency of electron transport between the perovskite layer and the adjacent layer is increased, and the photoelectric conversion efficiency can be improved.

From the viewpoint of preventing the occurrence of the above-mentioned pinholes and cracks and improving the photoelectric conversion efficiency, Rz is preferably 1 nm to 1000 nm, more preferably 1 nm to 500 nm, and even more preferably 5 nm to 200 nm.
If it is at least the above lower limit value, the above effect is further enhanced, and if it is at least the above upper limit value, the mechanical strength of the perovskite layer and / or the adjacent layer is weakened, or the unevenness of the joint surface K itself causes leakage. Can be prevented.
Rz may be larger than the thickness of the adjacent layer, but is preferably smaller than the thickness of the adjacent layer from the viewpoint of reducing the leakage frequency and improving the photoelectric conversion efficiency.

FIG. 9 is a cross-sectional view of the photoelectric conversion element cut in the thickness direction, including the boundary between the perovskite layer and the adjacent layer.
In the photoelectric conversion element according to the present invention, the reference length (L) is set as a horizontal side and the Rz (= Rp + Rv) is set in a cross-sectional view (see FIG. 9) including the joint surface K in the thickness direction of the perovskite layer. Of the area S (= L × Rz) of the quadrangle taken on the vertical side, the occupancy rate of the adjacent layer is preferably 10 to 90%. Here, the occupancy rate of the perovskite layer is 100% − (occupancy rate of the adjacent layer).

In FIG. 9, the area surrounded by the quadrangle is represented by S, the occupied area of the perovskite layer is represented by s1, and the occupied area of the adjacent layer is represented by s2. Here, the area S of the quadrangle = (area s1 of the occupied area of the perovskite layer) + (area s2 of the occupied area of the adjacent layer).

The occupancy of the adjacent layer is preferably 10 to 90%, more preferably 10 to 70%, and even more preferably 30 to 70%.
When it is at least the above lower limit value, the effect of preventing the occurrence of pinholes and cracks and improving the photoelectric conversion efficiency is further enhanced, and when it is at least the above upper limit value, the mechanical strength of the adjacent layer can be sufficiently maintained. it can.
As a method for measuring the occupancy of the adjacent layer, a cross section cut in the thickness direction of the solid-state junction type photoelectric conversion element to be measured is observed with a scanning electron microscope, and the junction surface K is specified by image processing. The method of obtaining the area s1 and the area s2 of the above is preferable. It is preferable to measure the area s1 and the area s2 at a plurality of locations (for example, 5 locations) for the same measurement target, and set the arithmetic mean thereof to the area s1 and the area s2, respectively.

Hereinafter, specific embodiments of the photoelectric conversion element will be illustrated with reference to the drawings.
[First Embodiment]
FIG. 1 is a cross-sectional view of the photoelectric conversion element 10A cut in the thickness direction.
In the photoelectric conversion element 10A shown in FIG. 1, the base material 4, the first conductive layer 1, the perovskite layer 3, and the second conductive layer 2 are laminated in this order.
The Rz (Rz—a) of the joint surface K (Ka) in contact with the perovskite layer 3 in the first conductive layer 1 which is the first adjacent layer is 1 nm or more. The joint surface K (Ka) is formed with a concavo-convex shape having an Rz (Rz-a) of 1 nm or more.
The Rz (Rz-b) of the joint surface K (K-b) in contact with the perovskite layer 3 in the second conductive layer 2 which is the second adjacent layer is preferably 1 nm or more. The uneven shape on the joint surface Kb in the figure is not drawn.

[Second Embodiment]
FIG. 2 is a cross-sectional view of the photoelectric conversion element 10B cut in the thickness direction.
In the photoelectric conversion element 10B shown in FIG. 2, a base material 4, a first conductive layer 1, an anchor layer 5 containing fine particles, a perovskite layer 3, and a second conductive layer 2 are laminated in this order.
The Rz (Rz-a) of the joint surface K (K-a) in contact with the perovskite layer 3 in the anchor layer 5 which is the first adjacent layer is 1 nm or more. The joint surface K (Ka) is formed with a concavo-convex shape having Rz (Rz-a) of 1 nm or more.
The anchor layer 5 may be a dense film or a porous film. In the case of a porous film, a part of the perovskite layer 3 may be contained inside the pores. When a part of the perovskite layer 3 is contained inside the porous anchor layer 5, and the part of the perovskite layer 3 ensures continuity between the perovskite layer 3 and the first conductive layer 1, the fine particles constituting the anchor layer 5 are insulated. It may be fine particles.
The Rz (Rz-b) of the joint surface K (K-b) in contact with the perovskite layer 3 in the second conductive layer 2 which is the second adjacent layer is preferably 1 nm or more. The uneven shape on the joint surface Kb in the figure is not drawn.

[Third Embodiment]
FIG. 3 is a cross-sectional view of the photoelectric conversion element 10C cut in the thickness direction.
In the photoelectric conversion element 10C shown in FIG. 3, the base material 4, the first conductive layer 1, the perovskite layer 3, and the second conductive layer 2 are laminated in this order.
The Rz (Rz—a) of the joint surface K (Ka) in contact with the perovskite layer 3 in the first conductive layer 1 which is the first adjacent layer is 1 nm or more. The joint surface K (Ka) is formed with a concavo-convex shape having Rz (Rz-a) of 1 nm or more.
The Rz (Rz-b) of the joint surface K (K-b) in contact with the perovskite layer 3 in the second conductive layer 2 which is the second adjacent layer is preferably 1 nm or more. The uneven shape on the joint surface Kb in the figure is not drawn.
The joint surface J1 in contact with the first conductive layer 1 of the base material 4 has a concave-convex shape similar to that of the joint surface K (Ka), and the joint surface of the base material 4 in contact with the first conductive layer 1. The maximum height roughness (Rz ") is set to 1 nm or more. As a result, the adhesion between the first conductive layer 1 and the base material 4 is improved.
Here, Rz "is the sum of the maximum peak height (Rp) and the maximum valley depth (Rv) within the reference length (L) at the joint surface J1 of the base material 4. This Rz" is JIS. It is synonymous with the maximum height roughness (Rz) defined in B0601-2001, and is measured by the method described above in accordance with the same standard.

[Fourth Embodiment]
FIG. 4 is a cross-sectional view of the photoelectric conversion element 10D cut in the thickness direction.
In the photoelectric conversion element 10D shown in FIG. 4, the base material 4, the first conductive layer 1, the N-type semiconductor layer 6, the perovskite layer 3, the P-type semiconductor layer 7, and the second conductive layer 2 are laminated in this order.
The Rz (Rz-a) of the joint surface K (K-a) in contact with the perovskite layer 3 in the N-type semiconductor layer 6 which is the first adjacent layer is 1 nm or more. The joint surface K (Ka) is formed with a concavo-convex shape having Rz (Rz-a) of 1 nm or more.
The N-type semiconductor layer 6 is made of a material different from that of the first conductive layer 1 and is formed of an N-type semiconductor. By providing the N-type semiconductor layer 6, it is possible to promote the photoelectrons generated in the perovskite layer 3 from flowing into the N-type semiconductor layer 6 and flowing toward the first conductive layer 1.
The P-type semiconductor layer 7 is made of a material different from that of the second conductive layer 2, and is formed of a P-type semiconductor. Since the P-type semiconductor layer 7 is provided, the holes generated in the perovskite layer 3 can be promoted to flow into the P-type semiconductor layer 7 and flow to the second conductive layer 2 side.
The Rz (Rz-b) of the bonding surface K (K-b) in contact with the perovskite layer 3 in the P-type semiconductor layer 7 which is the second adjacent layer is preferably 1 nm or more. The uneven shape on the joint surface Kb in the figure is not drawn.

[Fifth Embodiment]
FIG. 5 is a cross-sectional view of the photoelectric conversion element 10E cut in the thickness direction.
In the photoelectric conversion element 10E shown in FIG. 5, the base material 4, the first conductive layer 1, the N-type semiconductor layer 6, the anchor layer 5 containing fine particles, the perovskite layer 3, the P-type semiconductor layer 7 and the second conductive layer 2 are included. It is laminated in order.
The Rz (Rz-a) of the joint surface K (K-a) in contact with the perovskite layer 3 in the anchor layer 5 which is the first adjacent layer is 1 nm or more. The joint surface K (Ka) is formed with a concavo-convex shape having Rz (Rz-a) of 1 nm or more.
The anchor layer 5 may be a dense film or a porous film. In the case of a porous film, a part of the perovskite layer 3 may be contained inside the pores. When a part of the perovskite layer 3 is contained inside the porous anchor layer 5, and the part of the perovskite layer 3 ensures continuity between the perovskite layer 3 and the N-type semiconductor layer 6, the fine particles constituting the anchor layer 5 are insulated. It may be fine particles.
The N-type semiconductor layer 6 is made of a material different from that of the first conductive layer 1, the P-type semiconductor layer 7 is made of a material different from that of the second conductive layer 2, and the role of each semiconductor layer is the same as that of the fourth embodiment.
The Rz (Rz-b) of the bonding surface K (K-b) in contact with the perovskite layer 3 in the P-type semiconductor layer 7 which is the second adjacent layer is preferably 1 nm or more. The uneven shape on the joint surface Kb in the figure is not drawn.

[Sixth Embodiment]
FIG. 6 is a cross-sectional view of the photoelectric conversion element 10F cut in the thickness direction.
In the photoelectric conversion element 10F shown in FIG. 6, the base material 4, the first conductive layer 1, the N-type semiconductor layer 6, the perovskite layer 3, the P-type semiconductor layer 7, and the second conductive layer 2 are laminated in this order.
The Rz (Rz-a) of the joint surface K (K-a) in contact with the perovskite layer 3 in the N-type semiconductor layer 6 which is the first adjacent layer is 1 nm or more. The joint surface K (Ka) is formed with a concavo-convex shape having Rz (Rz-a) of 1 nm or more.
The N-type semiconductor layer 6 is made of a material different from that of the first conductive layer 1, the P-type semiconductor layer 7 is made of a material different from that of the second conductive layer 2, and the role of each semiconductor layer is the same as that of the fourth embodiment.
The Rz (Rz-b) of the bonding surface K (K-b) in contact with the perovskite layer 3 in the P-type semiconductor layer 7 which is the second adjacent layer is preferably 1 nm or more. The uneven shape on the joint surface Kb in the figure is not drawn.

The joint surface J1 in contact with the N-type semiconductor layer 6 in the first conductive layer 1 has a concave-convex shape similar to that of the joint surface K, and is the maximum of the joint surface in contact with the N-type semiconductor layer 6 in the first conductive layer 1. The height roughness (Rz') is 1 nm or more. As a result, the adhesion between the N-type semiconductor layer 6 and the first conductive layer 1 is improved, and the bonding area is further increased, so that the photoelectric conversion efficiency can be improved.
Here, Rz'is the sum of the maximum peak height (Rp) and the maximum valley depth (Rv) within the reference length (L) at the joint surface J1 of the first conductive layer 1. This Rz'is synonymous with the maximum height roughness (Rz) defined by JIS B0601-2001, and is measured by the method described above in accordance with the same standard.

[Seventh Embodiment]
FIG. 7 is a cross-sectional view of the photoelectric conversion element 10G cut in the thickness direction.
In the photoelectric conversion element 10G shown in FIG. 7, the base material 4, the first conductive layer 1, the N-type semiconductor layer 6, the perovskite layer 3, the P-type semiconductor layer 7, and the second conductive layer 2 are laminated in this order.
The Rz (Rz-a) of the joint surface K (K-a) in contact with the perovskite layer 3 in the N-type semiconductor layer 6 which is the first adjacent layer is 1 nm or more. The joint surface K (Ka) is formed with a concavo-convex shape having Rz (Rz-a) of 1 nm or more.
The N-type semiconductor layer 6 is made of a material different from that of the first conductive layer 1, the P-type semiconductor layer 7 is made of a material different from that of the second conductive layer 2, and the role of each semiconductor layer is the same as that of the fourth embodiment.
The Rz (Rz-b) of the bonding surface K (K-b) in contact with the perovskite layer 3 in the P-type semiconductor layer 7 which is the second adjacent layer is preferably 1 nm or more. The uneven shape on the joint surface Kb in the figure is not drawn.

The joint surface J1 in contact with the N-type semiconductor layer 6 in the first conductive layer 1 has a concave-convex shape similar to that of the joint surface K, and the Rz of the joint surface in contact with the N-type semiconductor layer 6 in the first conductive layer 1 'Is 1 nm or more. As a result, the adhesion between the N-type semiconductor layer 6 and the first conductive layer 1 is improved, and the bonding area is further increased, so that the photoelectric conversion efficiency can be improved.

The joint surface J2 in contact with the first conductive layer 1 of the base material 4 has a concave-convex shape similar to that of the joint surface J1, and the Rz "of the joint surface in contact with the first conductive layer 1 in the base material 4 is 1 nm or more. As a result, the adhesion between the first conductive layer 1 and the base material 4 is improved.
The above description of Rz'and Rz'is the same as the above description of Rz'and Rz', and will be omitted.

The photoelectric conversion elements of the first to seventh embodiments exemplified above all include the base material 4, but the layers other than the base material 4, for example, the first conductive layer 1, are sufficiently thick and self-supporting. If it is provided, the base material 4 may be omitted.

From the viewpoint of improving the production yield and photoelectric conversion efficiency of the photoelectric conversion element of the present invention, the roughness ratio represented by (Rz-a) / (Rz-b) is preferably 0.1 or more and 1000 or less, and 0. 2 or more and 100 or less are more preferable, 0.3 or more and 80 or less are further preferable, 0.5 or more and 50 or less are further preferable, 0.8 or more and 40 or less are further preferable, and 1.0 or more and 30 or less are particularly preferable. , 2.0 or more and 20 or less is most preferable. The Rz (Rz-a) of the bonding surface K (Ka) in which the adjacent layer (for example, the first adjacent layer) formed earlier in the manufacture of the photoelectric conversion element is in contact with the perovskite layer 3 is formed later in the manufacture. It is preferable that the adjacent layer (for example, the second adjacent layer) is larger than the Rz (Rz-b) of the joint surface K (K-b) in contact with the perovskite layer 3.

In the photoelectric conversion element according to the present invention, the total roughness obtained by adding (Rz-a) + (Rz-b) is preferably a value smaller than the thickness of the perovskite layer, and the thickness of the perovskite layer. It is more preferably 80% or less, and further preferably 60% or less of the thickness of the perovskite layer.

Hereinafter, the material and thickness of each layer will be described.
The following method is preferable as a method for measuring the thickness of each layer. The cross section cut in the thickness direction of the solid-state junction type photoelectric conversion element to be measured was observed with a scanning electron microscope, the boundary between each layer was identified by image processing, and 10 randomly selected points of each layer were selected for each layer. The thickness is measured and the arithmetic mean is taken as the thickness of each layer.

(First conductive layer 1)
The material of the first conductive layer 1 is not particularly limited as long as it is a conductive layer, and a material capable of forming a transparent layer is preferable. For example, tin-doped tin oxide (ITO), fluorine-doped tin oxide (FTO), and antimony are preferable. Metal oxides such as dope tin oxide (ATO), tin dioxide (SnO ₂ ), and zinc oxide (ZnO) are suitable. Further, any one or more metals selected from the group consisting of gold, silver, copper, aluminum, tungsten, nickel and chromium, carbon materials, conductive polymer materials, semiconductor materials which can be formed by the sol-gel method and the like can be used. Applicable.
The type of the material constituting the first conductive layer 1 may be one type or two or more types.
The thickness of the first conductive layer 1 is not particularly limited, and is preferably 100 nm to 500 nm, for example.
When the first conductive layer 1 forms a joint surface K having Rz (Rz-a) of 1 nm or more or Rz'1 nm or more, the thickness thereof is preferably 10 nm or more.

(Second conductive layer 2)
The description of the material and thickness of the second conductive layer 2 is the same as the description of the material and thickness of the first conductive layer 1, and thus is omitted.
From the viewpoint of irradiating the perovskite layer 3, which is the power generation layer of the photoelectric conversion element, with light, it is preferable that at least one of the first conductive layer 1 and the second conductive layer 2 is transparent.

(Perovskite layer 3)
The perovskite layer 3 is a layer containing a perovskite compound, and may be formed only from the perovskite compound or may contain other substances.
The type of perovskite compound is not particularly limited, and a known perovskite compound used in a solar cell can be applied, has a crystal structure, and exhibits light absorption by bandgap excitation like a typical compound semiconductor. Is preferable. _{For example, CH 3} NH ₃ PbI ₃ , a known perovskite compound, is ^{known to have an extinction coefficient (cm -1} ) per unit thickness that is an order of magnitude higher than that of the sensitizing dye of a dye-sensitized solar cell. There is.

The thickness of the perovskite layer 3 is, for example, preferably 10 nm to 10 μm, more preferably 50 nm to 1 μm, further preferably 100 nm to 500 nm, and particularly preferably 300 nm to 500 nm.
When it is at least the lower limit of the above range, the light absorption efficiency in the perovskite layer 3 is increased, and more excellent photoelectric conversion efficiency can be obtained.
When it is not more than the upper limit of the above range, the efficiency of the photoelectrons generated in the perovskite layer 3 reaching the first conductive layer 1 is increased, and more excellent photoelectric conversion efficiency can be obtained.

(Base material 4)
The type of the base material 4 is not particularly limited, and examples thereof include a transparent base material used for a photoelectrode of a conventional solar cell. Examples of the transparent substrate include a substrate made of glass or a synthetic resin, a flexible film made of a synthetic resin, and the like.

When the material of the transparent base material is a synthetic resin, examples of the synthetic resin include polyacrylic resin, polycarbonate resin, polyester resin, polyimide resin, polystyrene resin, polyvinyl chloride resin, and polyamide resin. Among these, polyester resins, particularly polyethylene naphthalate (PEN) and polyethylene terephthalate (PET), are preferable from the viewpoint of producing a thin, light and flexible photoelectric conversion element.

The combination of the thickness of the base material 4 and the material is not particularly limited, and examples thereof include a glass substrate having a thickness of 1 mm to 10 mm, a resin film having a thickness of 0.01 mm to 3 mm, and the like.

(Anchor layer 5)
The anchor layer 5 is a layer formed by bonding or binding a large number of fine particles to each other, and may be a dense film or a porous film.

The material of the fine particles is not particularly limited, and a material having conductivity is preferable. For example, metal oxides such as tin-doped tin oxide (ITO), fluorine-doped tin oxide (FTO), antimony-doped tin oxide (ATO); selected from the group consisting of gold, silver, copper, aluminum, tungsten, nickel and chromium. Any one or more metals; carbon materials; conductive polymer materials and the like can be mentioned.

Further, an N-type semiconductor can also be used as the material for the fine particles. Examples thereof include N-type oxide semiconductors having excellent electron conductivity such as titanium oxide (TiO ₂ ), zinc oxide (ZnO), tin oxide (SnO, SnO ₂ ), IGZO, and strontium titanate (SrTiO _3). ..

When the anchor layer 5 is a porous film, an insulator can be applied as a material for the fine particles, and an oxide constituting the insulating layer of a conventional semiconductor device can be mentioned. Specifically, zirconium dioxide, silicon dioxide, aluminum oxide _{(AlO, Al 2 O 3)} , magnesium oxide (MgO), and nickel oxide (NiO) can be mentioned. Of these, aluminum oxide (III) (Al ₂ O ₃ ) is particularly preferable from the viewpoint of forming a suitable Rz.

The average particle size of the fine particles constituting the anchor layer 5 is not particularly limited, and for example, 1 to 500 nm is preferable, 5 to 300 nm is more preferable, and 10 to 500 nm is further preferable. Within these suitable ranges, a concave-convex shape having an Rz (Rz-a) of 1 nm or more can be easily formed.
Here, the average particle size is the "arithmetic average value of the particle size" defined in JIS Z 8901: 2006 "Test powder and test particles", and the "Annex (regulation)" of the same standard. Method for measuring the average particle size of test particles 1 ”3. It is a value obtained based on the transmission electron microscopy.

The type of fine particles constituting the anchor layer 5 may be one type or two or more types.
The thickness of the anchor layer 5 is not particularly limited, and is preferably 10 nm to 300 nm, for example. When the anchor layer 5 forms a joint surface K having an Rz (Rz-a) of 1 nm or more, the thickness thereof is preferably 10 nm or more.

(N-type semiconductor layer 6)
The N-type semiconductor layer 6 may be a dense film or a porous film, but considering that the role of the N-type semiconductor layer 6 is to prevent backflow of electrons (generation of reverse current), it is dense. It is preferably a membrane.
When the N-type semiconductor layer 6 is a porous film, it is allowed that a part of the perovskite layer 3 is contained in the pores thereof. If this is allowed, there is a concern that the perovskite layer 3 and the first conductive layer 1 are directly conductive, and the above-mentioned role of the N-type semiconductor layer 6 cannot be fulfilled. If the N-type semiconductor layer 6 is a dense film, this concern does not occur.

The material of the N-type semiconductor layer 6 is not particularly limited, and for example, _{electron conduction of titanium oxide (TiO 2} ), zinc oxide (ZnO), tin oxide (SnO, SnO ₂ ), IGZO, strontium titanate (SrTiO ₃ ) and the like. An N-type oxide semiconductor having excellent properties can be exemplified.
The type of the N-type semiconductor constituting the N-type semiconductor layer 6 may be one type or two or more types.
It is preferable that the material of the N-type semiconductor layer 6 and the material of the first conductive layer 1 are different from each other.
It is preferable that the material of the N-type semiconductor layer 6 and the material of the anchor layer 5 are different from each other.

The thickness of the N-type semiconductor layer 6 is not particularly limited, and examples thereof include about 1 nm to 1 μm. When it is 1 nm or more, the above role is sufficiently fulfilled, and when it is 1 μm or less, the internal resistance can be suppressed low. When the N-type semiconductor layer 6 forms a bonding surface K (Ka) having an Rz (Rz-a) of 1 nm or more, the thickness of the N-type semiconductor layer 6 is preferably 10 nm or more, more preferably 100 nm or more. The thickness of the N-type semiconductor layer 6 is preferably larger than the Rz-a value, and more preferably twice or more the Rz-a value.

(P-type semiconductor layer 7)
The type of the P-type semiconductor that is the material of the P-type semiconductor layer 7 is not particularly limited, and may be an organic material or an inorganic material.
For example, a known P-type semiconductor of a hole transport layer of a solar cell can be applied. Examples of the organic material include 2,2', 7,7'-tetrakis (N, N-di-p-methoxyphenilamine) -9,9'-spirobifluorene (abbreviation: spiro-OMeTAD), Poly (3-hexylthiophene). (Abbreviation: P3HT), polytriarylamine (abbreviation: PTAA), etc. can be mentioned.
Examples of the inorganic materials, for example, CuI, CuSCN, CuO, and nickel compounds such as copper compounds and NiO of Cu ₂ O and the like.
The type of the P-type semiconductor constituting the P-type semiconductor layer 7 may be one type or two or more types.
It is preferable that the material of the P-type semiconductor layer 7 and the material of the second conductive layer 2 are different from each other.

The thickness of the P-type semiconductor layer 7 is not particularly limited, and is preferably 1 nm to 1000 nm, more preferably 5 nm to 500 nm, further preferably 30 nm to 500 nm, and particularly preferably 50 nm to 200 nm.
When it is equal to or more than the lower limit of the above range, a high electromotive force can be obtained.
When it is not more than the upper limit value in the above range, the internal resistance can be further reduced.
When the P-type semiconductor layer 7 forms a bonding surface K (K-b) having an Rz (Rz-b) of 1 nm or more, the thickness of the P-type semiconductor layer 7 is preferably 10 nm or more, more preferably 50 nm or more, and 100 nm or more. More preferred. The thickness of the P-type semiconductor layer 7 is preferably larger than the Rz-b value, and more preferably twice or more the Rz-b value.

<< Power generation of solid-state junction type photoelectric conversion element >>
When the perovskite layer 3 absorbs light, photoelectrons and holes are generated in the layer. When the anchor layer 5 and the N-type semiconductor layer 6 are provided, the photoelectrons move to the working electrode (positive electrode) formed by the first conductive layer 1 via these. On the other hand, when the P-type semiconductor layer 7 is provided, the holes move to the counter electrode (negative electrode) formed by the second conductive layer 2.
The current generated by the photoelectric conversion element is taken out to an external circuit via each of the extraction electrodes connected to the first conductive layer 1 and the second conductive layer 2.

<< Manufacturing method of solid-state junction type photoelectric conversion element >>
A second aspect of the present invention is a method for manufacturing a solid-state junction type photoelectric conversion element including a perovskite layer and an adjacent layer having a junction surface in contact with the perovskite layer. This production method involves applying a solution containing a compound for forming the perovskite layer to the joint surface of the adjacent layer to form a coating film (coating film forming step), and drying the coating film. It has a step of forming the perovskite layer (curing step).
The maximum height roughness (Rz) of the joint surface is 1 nm or more, and the Rz is the maximum mountain height (Rp) and the maximum valley depth (Rv) within the reference length (L) of the joint surface. Is the sum of. This Rz is synonymous with the maximum height roughness (Rz) defined by JIS B0601-2001, and is measured by the method described above in accordance with the same standard.

In the curing step, a solution containing a perovskite compound is applied and dried, and the coating film gradually shrinks to form a cured or crystallized perovskite layer. At this time, stress is generated inside the perovskite layer, which is gradually formed while the coating film shrinks, in a direction away from each other (direction along the joint surface).
For example, when manufacturing the photoelectric conversion element 10A of FIG. 1, consider a situation in which the perovskite layer 3 is formed while the coating film gradually shrinks on the joint surface K of the first conductive layer 1. In this situation, in the cross-sectional view of FIG. 1, the left half region and the right half region of the coating film (perovskite layer 3) are aggregated independently of each other, a crack (or pinhole) is generated in the center, and the left A stress is generated that forms the perovskite layer 3 separated into the half and the right half. This stress is naturally generated with drying due to physical properties such as surface tension of the solution constituting the coating film.

However, even if the above stress is generated, in the manufacturing method according to the present invention, a concave-convex shape is formed on the joint surface K, and the Rz of the joint surface K is 1 nm or more. It is possible to form the perovskite layer 3 in which holes) are not generated and leakage current is unlikely to be generated.
As this mechanism, since the uneven shape formed on the joint surface functions as a physical resistance to the above stress, it is considered that the fluidization or fragmentation of the coating film due to the stress is prevented.

In the curing step, drying the coating film means volatilizing the solvent contained in the coating film and removing the solvent to the extent that a cured perovskite layer 3 is obtained.
The smaller the amount of solvent remaining in the perovskite layer 3, the more preferable, and the content of the residual solvent with respect to the total mass (100%) of the perovskite layer 3 is preferably 0.1% or less, more preferably 0.01% or less.

Hereinafter, a method for forming each layer of the solid-state junction type photoelectric conversion element according to the present invention and a roughening method (method for forming an uneven shape) having an Rz of 1 nm or more will be described.
<Preparation of base material 4>
The base material 4 can be produced by a conventional method, and a commercially available product may be used.
Examples of the method for roughening the base material 4 include a known nanoimprint method.
Examples of the uneven shape to be formed include a line pattern, a dot pattern, a hole pattern, and the like.

<Formation of the first conductive layer 1>
The method of forming the first conductive layer 1 on the surface of the base material 4 is not particularly limited, and for example, a known film forming method such as a sputtering method or a vapor deposition method can be applied. A known sol-gel method in which a dispersion liquid containing a semiconductor precursor is applied to the surface of the base material 4 to form a conductive layer made of a semiconductor can also be applied.

As a method of roughening the first conductive layer 1, for example, a method of mechanically polishing the surface of the first conductive layer 1 with a grinder, sandpaper, buff, etc .; Examples thereof include a method of chemically forming irregularities by contacting them; a method of physically forming irregularities by irradiating the surface of the first conductive layer 1 with a laser; and the like.
When the uneven shape is formed in advance on the surface of the base material 4, the first conductive layer 1 is formed on the surface of the base material 4, so that the first conductive layer 1 having the uneven shape following the uneven shape of the base material 4 is formed. can do.

<Formation of N-type semiconductor layer 6>
The method for forming the N-type semiconductor layer 6 on the first conductive layer 1 is not particularly limited, and for example, a sputtering method, a vapor deposition method, or a dispersion liquid containing a precursor of the N-type semiconductor is applied to the surface of the first conductive layer 1. Examples thereof include a sol-gel method for coating.

Examples of the precursor of the N-type semiconductor include titanium tetrachloride (TiCl ₄ ), peroxotitanic acid (PTA), titanium alkoxide such as titanium ethoxyoxide and titanium isopropoxide (TTIP), zinc alkoxide, alkoxysilane, and zirconium. Examples thereof include metal alkoxides such as alkoxides.

Examples of the method for roughening the N-type semiconductor layer 6 include the same method as the above-mentioned method for roughening the first conductive layer 1.
When an uneven shape is formed in advance on the surface of the first conductive layer 1, an N-type semiconductor having an uneven shape that follows the uneven shape of the first conductive layer 1 by forming the N-type semiconductor layer 6 on the surface thereof. Layer 6 can be formed.

<Formation of anchor layer 5>
The method of forming the anchor layer 5 containing fine particles on the first conductive layer 1 or the N-type semiconductor layer 6 is not particularly limited, and for example, a semiconductor layer carrying a sensitizing dye of a conventional dye-sensitized solar cell can be used. The method of forming is applicable.
Specifically, for example, an anchor made of fine particles is obtained by applying a slurry containing fine particles made of a conductor or an N-type semiconductor to the surface of the first conductive layer 1 or the N-type semiconductor layer 6 by a spin coating method and drying the slurry. Layer 5 can be formed.
By spraying the fine particles onto the surface of the first conductive layer 1 or the N-type semiconductor layer 6, an anchor layer 5 of a porous film or a dense film (non-porous film) made of the fine particles can be formed.

As the method of spraying the fine particles, a known method can be applied, for example, an aerosol deposition method (AD method), an electrostatic fine particle coating method (electrostatic spray method) for accelerating fine particles by electrostatic force, a cold spray method, and the like. Can be mentioned.

Examples of the method of forming the uneven shape on the surface of the anchor layer 5 include the same method as the above-mentioned method of roughening the first conductive layer 1.
Examples thereof include a method in which the particle size distribution of the fine particles contained in the slurry is a bimodal distribution or a multimodal distribution, and the mixing ratio of the large diameter particles and the small diameter particles is appropriately adjusted.
In the spraying of the fine particles, a method of appropriately adjusting the sweeping speed of the spray nozzle, the spraying speed, the mixing ratio of the sprayed powder and the conveyed gas (spraying powder density), and the like can be mentioned.

<Formation of perovskite layer 3>
As a method of forming the perovskite layer 3 on the adjacent layer (for example, the first conductive layer 1, the anchor layer 5 or the N-type semiconductor layer 6), for example, a raw material solution in which a perovskite compound or a precursor of the perovskite compound is dissolved is used. Examples thereof include a method of forming a perovskite layer by applying it to the surface of the adjacent layer to form a coating film composed of a solution having a desired thickness, and drying the solvent contained in the coating film.

When the adjacent layer is a porous layer, the raw material solution permeates into the pores of the adjacent layer, and a part of the perovskite layer 3 is formed inside the adjacent layer.

The method of applying the raw material solution to the surface of the adjacent layer is not particularly limited, and for example, a known method such as a gravure coating method, a bar coating method, a printing method, a spray method, a spin coating method, a dip method, or a die coating method is applied. it can.

The concentration of the raw material in the raw material solution is not particularly limited, and it is preferable that the concentration is such that the raw material solution is sufficiently dissolved or dispersed and the raw material solution can be coated with a uniform thickness by the coating method.

The thickness of the coating film immediately after being formed by applying the raw material solution to the adjacent layer (before drying) is in a range thicker than the Rz value of the joint surface of the adjacent layer, for example, in the range of 10 nm to 10 μm. It is preferable to apply.

The method for drying the coating film is not particularly limited, and methods such as natural drying, vacuum drying, and warm air drying can be applied.
The drying temperature of the coating film may be a temperature at which crystallization of the perovskite compound (curing of the coating film) proceeds sufficiently, and examples thereof include a range of 40 to 150 ° C.
The degree of the drying treatment is preferably such that the content of the solvent with respect to the total mass (100%) of the cured perovskite layer is 0.1% or less, and it is dried until 0.01% or less. Is more preferable.
As a method for drying the coating film, a method of naturally drying at room temperature of 10 to 40 ° C. or a method of gently blowing warm air of about 35 to 70 ° C. on the coated surface of the raw material solution to dry the coating film is preferable. Thereby, it is possible to easily obtain the relationship that the Rz-a of the first adjacent layer formed earlier is larger than the Rz-b of the second adjacent layer formed later.

After applying the raw material solution to the adjacent layer, before the coated surface is completely dried, a poor solvent in which the perovskite compound is difficult to dissolve is dropped onto the coated surface, and the poor solvent is applied onto the coated surface. After diffusion, the perovskite layer is formed by a method of naturally drying at room temperature of 10 to 40 ° C. or a method of gently blowing warm air of about 40 to 70 ° C. on the coated surface of the raw material solution to dry. Is more preferable. Thereby, the relationship of Rz-a> Rz-b can be obtained more easily.

The solubility parameter (δ, SP value) of the poor solvent is preferably 8.5 or more, more preferably 9.0 or more, and further preferably 9.5 or more. As a guideline for the upper limit of the SP value, for example, 12.0 can be mentioned.

The perovskite compound is not particularly limited as long as it can generate an electromotive force by light absorption, and a known perovskite compound can be applied. Among them, the following composition formula (1): which can form perovskite-type crystals and has an organic component and an inorganic component in a single compound:
ABX ₃ ... (1)
The perovskite compound represented by is preferable.

In the composition formula (1), A represents an organic cation, B represents a metal cation, and X represents a halogen ion. In the perovskite crystal structure, the B site may be octahedrally coordinated with respect to the X site. It is considered that the metal cation of the B site and the atomic orbital of the halogen ion of the X site are mixed to form a valence band and a conduction band involved in photoelectric conversion.

The metal constituting the metal cation represented by B in the composition formula (1) is not particularly limited, and examples thereof include Cu, Ni, Mn, Fe, Co, Pd, Ge, Sn, Pb, and Eu. Of these, Pb and Sn, which can easily form a highly conductive band by hybridizing the halogen ion of the X site with the atomic orbital, are preferable.
The metal cations constituting the B site may be one kind or two or more kinds.

The halogen constituting the halogen ion represented by X in the composition formula (1) is not particularly limited, and examples thereof include F, Cl, Br, and I. Of these, Cl, Br and I, which can easily form a highly conductive band due to the hybrid orbital of the B site with the metal cation, are preferable.
The halogen ions constituting the X site may be one type or two or more types.

The organic group constituting the organic cation represented by A in the composition formula (1) is not particularly limited, and examples thereof include an alkylammonium derivative and a formamidinium derivative.
The organic cations constituting the A site may be one kind or two or more kinds.

Examples of the alkylammonium derivative include methylammonium, dimethylammonium, trimethylammonium, ethylammonium, propylammonium, isopropylammonium, tert-butylammonium, pentylammonium, hexylammonium, octylammonium, phenylammonium and the like, and have 1 to 6 carbon atoms. Primary or secondary ammonium having an alkyl group of. Of these, methylammonium is preferable because perovskite crystals can be easily obtained.

Examples of the formamidinium derivative include formamidinium, methylformamidinium, dimethylformamidinium, trimethylformamidinium, and tetramethylformamidinium. Of these, formamidinium, in which perovskite crystals can be easily obtained, is preferable.

Suitable perovskite compounds represented by the composition formula (1) include, for example, CH ₃ NH ₃ PbI ₃ , CH ₃ NH ₃ PbI _3-h Cl _h (h represents 0 to ₃ ), CH 3 NH ₃ PbI. The following composition formula (2): such as _3-j Br _{j (j represents 0 to 3):}
RNH ₃ PbX ₃ ... (2)
Examples thereof include alkylamino lead halides represented by. In the composition formula (2), R represents an alkyl group and X represents a halogen ion. Since the perovskite compound having this composition formula has a wide absorption wavelength range and can absorb a wide wavelength range of sunlight, excellent photoelectric conversion efficiency can be obtained.

The alkyl group represented by R in the composition formula (2) is preferably a linear, branched or cyclic saturated or unsaturated alkyl group having 1 to 6 carbon atoms, and is a direct group having 1 to 6 carbon atoms. It is more preferably a chain saturated alkyl group, and even more preferably a methyl group, an ethyl group or an n-propyl group. With these suitable alkyl groups, perovskite crystals can be easily obtained.

In the formation of the perovskite layer 3, the precursor contained in the raw material solution includes, for example, a halide (BX) containing a metal ion of B site and a halogen ion of X site described above, and an organic substance of A site described above. Halides (AX) containing halogen ions of cations and X-sites can be mentioned.
A single raw material solution containing a halide (AX) and a halide (BX) may be applied to the adjacent layer, or two raw material solutions containing each halide individually may be applied to the adjacent layer in order. May be applied to.

The solvent of the raw material solution is not particularly limited as long as it is a solvent that dissolves or disperses the raw material and does not damage the adjacent layer, and is, for example, ester, ketone, ether, alcohol, glycol ether, amide, nitrile, carbonate, or hydrocarbon. Examples thereof include compounds such as hydrocarbons, hydrocarbons, solvents, sulfoxides, and formamides.

As an example, the composition formula (2) is obtained by dissolving an alkylamine halide and lead halide in a mixed solvent of γ-butyrolactone (GBL) and dimethyl sulfoxide (DMSO), applying the solution to the adjacent layer, and drying the solution. ), A perovskite crystal composed of the perovskite compound represented by) can be obtained. Further, as described in Non-Patent Document 2, a solvent that does not dissolve the crystal but is miscible with GBL or DMSO, such as toluene or chloroform, is applied onto the perovskite crystal, and then annealing is performed at about 100 ° C. Processing may be added. This additional treatment may improve the stability of the crystal and increase the photoelectric conversion efficiency.

<Formation of P-type semiconductor layer 7>
The method for forming the P-type semiconductor layer 7 on the perovskite layer 3 is not particularly limited. For example, a solution in which the P-type semiconductor is dissolved or dispersed in a solvent in which the perovskite compound constituting the perovskite layer 3 is difficult to dissolve is prepared. A method of obtaining the P-type semiconductor layer 7 by applying this solution to the surface of the perovskite layer 3 and drying it can be mentioned.

<Formation of the second conductive layer 2>
The method of forming the second conductive layer 2 on the perovskite layer 3 or the P-type semiconductor layer 7 is not particularly limited, and for example, the above-mentioned method of forming the first conductive layer 1 can be applied.

By the above steps, a photoelectric conversion element in which a base material 4, a first conductive layer 1, an N-type semiconductor layer 6, an anchor layer 5, a perovskite layer 3, a P-type semiconductor layer 7, and a second conductive layer 2 are laminated in this order. Can be manufactured.

In the above, the method of sequentially laminating each layer from the first conductive layer 1 to the second conductive layer 2 has been described. The method for manufacturing a photoelectric conversion element according to the present invention is not limited to the above order, and a method of sequentially laminating each layer from the second conductive layer 2 to the first conductive layer 1 may be adopted.

[Example 1]
A transparent resin substrate (PEN substrate) having a transparent conductive layer (first conductive layer) made of ITO formed on the surface was prepared. The unnecessary part of the first conductive layer is etched with hydrochloric acid to eliminate the possibility that the unnecessary part of the first conductive layer unintentionally contacts other conductive members to cause a short circuit or a leak current. did.
Next, by rubbing a buff on the surface of ITO, the surface was roughened.
Subsequently, a DMF solution in which 1 M of CH ₃ NH ₃ I and Pb I ₂ was dissolved was spin-coated on the substrate and dried by heating at 100 ° C. for 60 minutes to form a perovskite layer (power generation layer) having a thickness of 300 nm. Further, a second conductive layer made of an Au film having a thickness of 100 nm was formed on the perovskite layer by a physical vapor deposition method to produce a solid-bonded photoelectric conversion element.

The cross section of this device is observed by SEM, the ITO layer and the perovskite layer are distinguished by contrast, and the maximum mountain height within the reference length (L) of 1 μm in the horizontal direction along the joint surface between the ITO layer and the perovskite layer. Rz-a, which is the sum of (Rp) and the maximum valley depth (Rv), was measured at a plurality of points (5 points). The Rz-a values were all 4 to 12 nm, and the average value of Rz-a was 8 nm.
The cross section is observed by SEM, the perovskite layer and the Au film are distinguished by contrast, and the maximum mountain height (Rp) within the reference length (L) of 1 μm in the horizontal direction along the joint surface between the perovskite layer and the Au film. ) And Rz-b, which is the sum of the maximum valley depth (Rv), was measured at a plurality of points (5 points). The average value of Rz-b was 268 nm.
From the above measurement, Rz-a mean value / Rz-b mean value = 0.03.

The frequency of leakage current generation (leakage frequency) of the 20 solid-state junction type photoelectric conversion elements manufactured by the above method was evaluated by the following method. As a result, 15 passed and 5 (25%) failed.

The leakage frequency of each photoelectric conversion element was evaluated by measuring the current-voltage characteristic in a dark state with a source meter and measuring the parallel resistance Rsh. Here, Rsh in the dark state is defined as | current gradient with respect to voltage | = | voltage displacement | / | current displacement | near 0V. In this definition, the smaller the absolute value of Rsh, the easier it is for leak current to flow. Therefore, the photoelectric conversion element having an absolute value of Rsh of 1000 or less was evaluated as a defective product in which a leak current was generated.

A power supply (manufactured by KEITHLEY, 236 models) is connected between the electrodes of the 20 solid-state junction type photoelectric conversion elements, and photoelectric conversion efficiency is achieved using a one-light source type solar simulator (manufactured by Yamashita Denso Co., Ltd.) ^{with an intensity of 100 mW / cm 2.} Was measured. The arithmetic mean of these measured values was determined as the average photoelectric conversion efficiency (average efficiency).
The above results are shown in Table 1.

[Example 2]
A dispersion liquid in which 20 wt% of ITO nanoparticles having a particle size of 20 nm is dispersed in ethanol is applied onto the etched ITO in the same manner as in Example 1 by a spin coating method to form an anchor layer having a thickness of 150 nm composed of ITO nanoparticles. did. Then, in the same manner as in Example 1, a perovskite layer and a second conductive layer were formed, and a solid-bonded photoelectric conversion element was produced and evaluated.

[Example 3]
On the ITO etched in the same manner as in Example 1, _{a dispersion liquid in which 20 wt% of TiO 2} nanoparticles having a particle size of 15 nm was dispersed in ethanol was applied by a spin coating method, and an anchor layer having a thickness of 150 nm composed of _{TiO 2 nanoparticles was applied.} Was formed. Then, in the same manner as in Example 1, a perovskite layer and a second conductive layer were formed, and a solid-bonded photoelectric conversion element was produced and evaluated.

[Example 4]
_{A TiO 2} film (N-type semiconductor layer) having a thickness of 50 nm was formed on the ITO etched in the same manner as in Example 1 by a sputtering method. Next, the surface was roughened by rubbing a buff on the surface of the _{TiO 2 film.}
Subsequently, after forming a perovskite layer in the same manner as in Example 1, a P-type semiconductor layer having a thickness of 100 nm was formed by spin-coating a chlorobenzene solution in which 65 mM spiro-OMeTAD was dissolved. A second conductive layer made of an Au film having a thickness of 100 nm was formed on the P-type semiconductor layer to produce a solid-state junction type photoelectric conversion element. This was evaluated in the same manner as in Example 1.

[Example 5]
_{A TiO 2} film (N-type semiconductor layer) having a thickness of 50 nm was formed on the ITO etched by the same method as in Example 1 by a sputtering method. _{Next, a dispersion in which 20 wt% of TiO 2} nanoparticles having a particle size of 15 nm was dispersed in ethanol was applied by a spin coating method to form an anchor layer having a thickness of 150 nm composed of _{TiO 2 nanoparticles.} Subsequently, a perovskite layer, a P-type semiconductor layer, and a second conductive layer were formed in the same manner as in Example 4, and a solid-bonded photoelectric conversion element was produced and evaluated.

[Example 6]
_{A TiO 2} film (N-type semiconductor layer) having a thickness of 50 nm was formed on the ITO etched by the same method as in Example 1 by a sputtering method. _{Next, a dispersion in which 20 wt% of Al 2} O ₃ nanoparticles having a particle size of 20 nm was dispersed in ethanol was applied by a spin coating method to form an anchor layer having a thickness of 150 nm composed of _{Al 2} O _{3 nanoparticles.} Subsequently, a perovskite layer, a P-type semiconductor layer, and a second conductive layer were formed in the same manner as in Example 4, and a solid-bonded photoelectric conversion element was produced and evaluated.

[Example 7]
The surface was roughened by rubbing a buff on the etched ITO surface in the same manner as in Example 1. _{Next, a TiO 2} film (N-type semiconductor film) having a thickness of 50 nm was formed by a sputtering method. The TiO ₂ film was formed with irregularities reflecting the irregularities of ITO. Subsequently, a perovskite layer, a P-type semiconductor layer, and a second conductive layer were formed in the same manner as in Example 4, and a solid-bonded photoelectric conversion element was produced and evaluated.

[Example 8]
In Example 4, a DMF solution for forming a perovskite layer was spin-coated, and warm air at 40 ° C. was gently blown onto the coating film surface to dry the perovskite layer, except that a perovskite layer having a thickness of 300 nm was formed. , A solid-state junction type photoelectric conversion element was produced in the same manner as in Example 4. This was evaluated in the same manner as in Example 4.

[Example 9]
In Example 2, a DMF solution for forming a perovskite layer was spin-coated, and warm air at 40 ° C. was gently blown onto the coating film surface to dry the perovskite layer, except that a perovskite layer having a thickness of 300 nm was formed. , A solid-state junction type photoelectric conversion element was produced in the same manner as in Example 2. This was evaluated in the same manner as in Example 2.

[Example 10]
In Example 5, a DMF solution for forming a perovskite layer was spin-coated, and warm air at 40 ° C. was gently blown onto the coating film surface to dry the perovskite layer, except that a perovskite layer having a thickness of 300 nm was formed. , A solid-bonded photoelectric conversion element was produced in the same manner as in Example 5. This was evaluated in the same manner as in Example 5.

[Example 11]
In Example 8, a DMF solution for forming a perovskite layer was spin-coated, an appropriate amount of toluene was dropped on the coating film surface to diffuse the toluene over the entire coating film surface, and then warm air at 40 ° C. was gently blown. A solid-bonded photoelectric conversion element was produced in the same manner as in Example 8 except that a perovskite layer having a thickness of 300 nm was formed by spraying and drying. This was evaluated in the same manner as in Example 8.

[Example 12]
In Example 9, a DMF solution for forming a perovskite layer was spin-coated, an appropriate amount of toluene was dropped on the coating film surface to diffuse the toluene over the entire coating film surface, and then warm air at 40 ° C. was gently blown. A solid-bonded photoelectric conversion element was produced in the same manner as in Example 9 except that a perovskite layer having a thickness of 300 nm was formed by spraying and drying. This was evaluated in the same manner as in Example 9.

[Example 13]
In Example 10, a DMF solution for forming a perovskite layer was spin-coated, an appropriate amount of toluene was dropped on the coating film surface to diffuse the toluene over the entire coating film surface, and then warm air at 40 ° C. was gently blown. A solid-bonded photoelectric conversion element was produced in the same manner as in Example 10 except that a perovskite layer having a thickness of 300 nm was formed by spraying and drying. This was evaluated in the same manner as in Example 10.

[Example 14]
In Example 12, a solid as in Example 12 except that a perovskite layer having a thickness of 300 nm was formed by diffusing toluene over the entire coating film surface and then gently blowing hot air at 100 ° C. to dry it. A junction type photoelectric conversion element was manufactured. This was evaluated in the same manner as in Example 9.

[Example 15]
In Example 13, a solid as in Example 13 except that a perovskite layer having a thickness of 300 nm was formed by diffusing toluene over the entire coating film surface and then gently blowing hot air at 100 ° C. to dry it. A junction type photoelectric conversion element was manufactured. This was evaluated in the same manner as in Example 13.

[Comparative Example 1]
A PEN substrate having an etched ITO surface was obtained in the same manner as in Example 1. The perovskite layer and the second conductive layer were formed by the same method as in Example 1 without roughening the ITO surface, and a solid-bonded photoelectric conversion element was produced and evaluated.
As a result, Rz was less than 1 nm, which is the measurement limit of the measurement method.

[Comparative Example 2]
_{A TiO 2} film was formed in the same manner as in Example 4, the surface was not roughened, and then a perovskite layer, a P-type semiconductor layer, and a second conductive layer were formed in the same manner as in Example 4. A solid-state junction type photoelectric conversion element was manufactured and evaluated.

Table 1 shows the configuration of the solid-state junction type photoelectric conversion element manufactured above and the evaluation results. Each symbol in Table 1 has the following meanings: S: base material, C1: first conductive layer, N: N-type semiconductor layer, A (ITO): ITO anchor layer, A (TiO ₂ ): TiO ₂ anchor layer, A (Al ₂ O ₃ ): _{Represents Al 2} O ₃ anchor layer, E: perovskite layer, P: P-type semiconductor layer, C2: second conductive layer.

FIG. 10 shows a graph plotting the relationship between the average value of Rz-a of each example and each comparative example and the leak occurrence frequency.
FIG. 11 is a graph plotting the relationship between the roughness ratio represented by (average value of Rz-a) / (average value of Rz-b) of each Example and each comparative example and the average value of photoelectric conversion efficiency. Is shown.

From Examples 8 to 13, it is clear that by gently blowing warm air during the formation of the perovskite layer, the Rz-b value is remarkably lowered, and the production yield and the photoelectric conversion efficiency are remarkably improved.
From Examples 11 to 13, when the perovskite layer was formed, a layer of a poor solvent was laminated on the perovskite layer, and then warm air was gently blown to further reduce the Rz-b value and the production yield. And it is understood that the photoelectric conversion efficiency is further improved.
From Examples 14 to 15, it is understood that the temperature of the warm air blown at the time of forming the perovskite layer is preferably less than 100 ° C, more preferably about 40 to 70 ° C.
From the above results, it is clear that the solid-state junction type photoelectric conversion element according to the present invention is less likely to generate a leak current and is manufactured with a good yield.
Examples 1 to 8, 11, 14 to 15 are comparative examples.

The configurations and combinations thereof in each of the embodiments described above are examples, and the configurations can be added, omitted, replaced, and other changes are possible without departing from the spirit of the present invention.

1 ... 1st conductive layer, 2 ... 2nd conductive layer, 3 ... Perobskite layer, 4 ... Base material, 5 ... Anchor layer, 6 ... N-type semiconductor layer, 7 ... P-type semiconductor layer, K ... Bonding surface, J1, J2 ... Bonding surface, 10A-10G ... Solid junction type photoelectric conversion element

Claims (12)

A solid-state junction type photoelectric conversion element having a first conductive layer, a perovskite layer, and a second conductive layer in this order.
In two adjacent layers adjacent to both sides of the perovskite layer, the maximum height roughness of the bonding surface in contact with the perovskite layer of the first adjacent layer (Rz-a), and, in contact with the perovskite layer of the second adjacent layer The maximum height roughness (Rz-b) of the joint surface is 1 nm or more,
The (Rz-a) is the sum of the maximum mountain height (Rp) and the maximum valley depth (Rv) within the reference length (L) at the joint surface of the first adjacent layer.
The (Rz-b) is the sum of the maximum mountain height (Rp) and the maximum valley depth (Rv) within the reference length (L) at the joint surface of the second adjacent layer.
A solid-state junction type photoelectric conversion element having a roughness ratio represented by (Rz-a) / (Rz-b) of 1.51 or more and 20 or less. Of the area S (= L × Rz) of a quadrangle with the reference length (L) as the horizontal side and the ( Rz—a) as the vertical side in a cross-sectional view including the joint surface in the thickness direction. The solid-state junction type photoelectric conversion element according to claim 1, wherein the occupancy of the adjacent layer is 10 to 90%. The solid-state junction type photoelectric conversion element according to claim 1 or 2, wherein the first conductive layer is the first adjacent layer. An anchor layer containing fine particles is provided between the first conductive layer and the perovskite layer.
The solid-state junction type photoelectric conversion element according to claim 1 or 2 , wherein the anchor layer is the first adjacent layer. An N-type semiconductor layer is provided between the first conductive layer and the perovskite layer.
The solid-state junction type photoelectric conversion element according to claim 1 or 2, wherein the N-type semiconductor layer is the first adjacent layer. An N-type semiconductor layer and an anchor layer containing fine particles are provided between the first conductive layer and the perovskite layer in this order.
The solid-state junction type photoelectric conversion element according to claim 1 or 2 , wherein the anchor layer is the first adjacent layer. An N-type semiconductor layer is provided between the first conductive layer and the perovskite layer.
The N-type semiconductor layer is the first adjacent layer.
The first conductive layer is adjacent to the N-type semiconductor layer, and the maximum height roughness (Rz') of the joint surface of the first conductive layer in contact with the N-type semiconductor layer is 1 nm or more.
The Rz'is the sum of the maximum peak height (Rp) and the maximum valley depth (Rv) within the reference length (L) of the first conductive layer at the joint surface, according to claim 1 or 2. The solid-state junction type photoelectric conversion element described. A P-type semiconductor layer is provided between the perovskite layer and the second conductive layer.
The solid-state junction type photoelectric conversion element according to any one of claims 1 to 7 , wherein the P-type semiconductor layer is the second adjacent layer. A base material in contact with the surface of the first conductive layer opposite to the perovskite layer is provided.
The maximum height roughness (Rz ") of the joint surface of the base material in contact with the first conductive layer is 1 nm or more.
The Rz ”is any one of claims 1 to 8, which is the sum of the maximum peak height (Rp) and the maximum valley depth (Rv) within the reference length (L) at the joint surface of the base material. The solid-state junction type photoelectric conversion element according to claim 1. A solid-bonded photoelectric having a perovskite layer, a first adjacent layer having a bonding surface in contact with the perovskite layer, and a second adjacent layer having a bonding surface in contact with the first adjacent layer of the perovskite layer on the opposite side. It is a method of manufacturing a conversion element.
A step of applying a solution containing a compound for forming the perovskite layer to the joint surface of the first adjacent layer to form a coating film, and a step of forming the perovskite layer by drying the coating film.
A step of forming the second adjacent layer on the joint surface of the second adjacent layer of the perovskite layer.
The maximum height roughness (Rz-a) of the joint surface of the first adjacent layer is 1 nm or more.
The maximum height roughness (Rz-b) of the joint surface of the second adjacent layer is 1 nm or more.
The roughness ratio represented by (Rz-a) / (Rz-b) is 1.51 or more and 20 or less.
The (Rz-a) is the sum of the maximum mountain height (Rp) and the maximum valley depth (Rv) within the reference length (L) at the joint surface of the first adjacent layer.
The (Rz-b) is a solid junction type which is the sum of the maximum peak height (Rp) and the maximum valley depth (Rv) within the reference length (L) at the junction surface of the second adjacent layer. A method for manufacturing a photoelectric conversion element. The method for producing a solid-bonded photoelectric conversion element according to claim 10, wherein the coating film is dried by blowing warm air at 40 to 60 ° C. to form the perovskite layer. The method for producing a solid-bonded photoelectric conversion element according to claim 10 or 11, wherein the coating film is dried after dropping a poor solvent for the compound onto the coating film to form the perovskite layer.

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