Apparatus for manufacturing photoelectric conversion elements, and conveyor rolls

Abstract

To improve the efficiency of photoelectric conversion element manufacturing. [Solution] The photoelectric conversion element manufacturing apparatus includes a drying chamber for drying a substrate coated with a perovskite precursor compound, and a transport roll positioned within the drying chamber near the transport path of the substrate coated with the precursor compound, wherein the surface of the transport roll is a black plated layer. Preferably, the surface of the transport roll is a black anodized plated layer, and the apparatus further includes a heating device for heating the space within the drying chamber. Preferably, a plurality of transport rolls are arranged at equal intervals along the transport path of the substrate coated with the precursor compound.

Description

Technical Field

[0001] The present invention relates to a manufacturing apparatus for a photoelectric conversion element and a conveyance roll.

Background Art

[0002] For example, Patent Document 1 discloses a method for manufacturing a photoelectric conversion element including a photoelectric conversion layer having a perovskite structure, the method comprising: applying a coating solution containing a precursor compound of a perovskite structure and an organic solvent onto an electrode to form a coating film; and forming a part of the drying of the coating film in an atmosphere containing the organic solvent in a gas phase. A manufacturing apparatus for a photoelectric conversion element using this method is also disclosed.

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] An object of the present invention is to improve the efficiency of manufacturing a photoelectric conversion element having a perovskite structure.

Means for Solving the Problems

[0005] The manufacturing apparatus for a photoelectric conversion element according to the present invention includes a drying chamber for drying a substrate coated with a precursor compound of a perovskite structure, and a conveyance roll disposed near a conveyance path of the substrate coated with the precursor compound in the drying chamber, wherein a surface of the conveyance roll is a black plating layer.

[0006] Preferably, the conveyance roll has a black anodic oxidation plating layer formed on a surface of a metal roll, and further includes a heating device for heating a space in the drying chamber.

[0007] Preferably, the transport rolls are arranged at equal intervals along the transport path of the substrate coated with the precursor compound.

[0008] Furthermore, the conveying roll according to the present invention is a conveying roll for drying a perovskite precursor compound, and has a black or reddish-brown plating layer on its surface. [Effects of the Invention]

[0009] According to the present invention, the manufacturing of photoelectric conversion elements having a perovskite structure can be made more efficient. [Brief explanation of the drawing]

[0010] [Figure 1] This is a schematic diagram showing an example of the configuration of the photoelectric conversion element 10 manufactured according to the embodiment. [Figure 2] This diagram schematically illustrates a manufacturing apparatus that continuously produces a photoelectric conversion layer using a roll-to-roll method. [Modes for carrying out the invention]

[0011] Hereinafter, embodiments of the present invention will be described with reference to the drawings. Figure 1 is a schematic diagram showing an example of the configuration of a photoelectric conversion element 10 manufactured according to the embodiment. As illustrated in Figure 1, a first electrode 11, a first buffer layer 12, a photoelectric conversion layer 13, a second buffer layer 14, and a second electrode 15 are stacked on a substrate 16. The first electrode 11 and the second electrode 15 become the anode or cathode and electricity is extracted from them. The photoelectric conversion layer 13 is a material that is excited by light incident through the substrate 16, the first electrode 11 and the first buffer layer 12, or the second electrode 15 and the second buffer layer 14, and generates electrons or holes in the first electrode 11 and the second electrode 15. The first buffer layer 12 and the second buffer layer 14 are layers that exist between the photoelectric conversion element and the two electrodes, and in the embodiment, they are not necessarily essential constituent materials. In this embodiment, the photoelectric conversion element refers to a solar cell or sensor having a perovskite structure material in which the photoelectric conversion layer is formed by coating.

[0012] (Circuit board 16) The substrate 16 is for supporting other components. It is necessary that electrodes can be formed on the surface of the substrate 16. For this reason, it is preferable that the substrate 16 does not deteriorate due to the heat generated during electrode formation or due to contact with organic solvents. Examples of materials for the substrate 16 include inorganic materials such as alkali-free glass and quartz glass, organic materials such as polyethylene, polyethylene terephthalate (PET), polyethylene naphthalate (PEN), polyimide, polyamide, polyamide-imide, liquid crystal polymer, and cycloolefin polymer, and metallic materials such as stainless steel (SUS) and silicon.

[0013] The substrate 16 may be transparent or opaque, and is appropriately selected depending on the structure of the intended photoelectric conversion element. When light is incident from the surface of the substrate 16, a transparent substrate is used. When light is incident from the opposite side of the substrate 16, the electrode 5 can be made transparent or semi-transparent, and the substrate 16 can be opaque. The thickness of the substrate is not particularly limited, as long as it has sufficient strength to support the other components.

[0014] When the substrate 16 is positioned on the light incident surface side, an anti-reflective film, for example, a moth-eye structure, can be installed on the light incident surface. By using such a structure, it is possible to efficiently capture light and improve the energy conversion efficiency of the cell. The moth-eye structure has a regular arrangement of protrusions of about 100 nm on its surface, and because the refractive index in the thickness direction changes continuously due to this protrusion structure, the discontinuous change in refractive index is eliminated by mediating with an anti-reflective film, so light reflection is reduced and cell efficiency is improved.

[0015] (First electrode 11 and second electrode 15) The first electrode 11 and the second electrode 15 can be selected from any conventionally known conductive material. However, the material of the electrode on the light incident surface side should be selected from a transparent or translucent conductive material. Examples of transparent or translucent electrode materials include conductive metal oxide films and translucent metal thin films.

[0016] Specifically, films (such as NESA) made using conductive glass composed of indium oxide, zinc oxide, tin oxide, and their composites such as indium tin oxide (ITO), fluorine-doped tin oxide (FTO), and indium zinc oxide, as well as gold, platinum, silver, copper, etc., are used. ITO or FTO are particularly preferred as conductive oxides.

[0017] The electrode thickness is preferably 30 to 300 nm when the electrode material is ITO. If the electrode thickness is less than 30 nm, the conductivity tends to decrease and the resistance tends to increase. High resistance can cause a decrease in photoelectric conversion efficiency. On the other hand, if the electrode thickness is greater than 300 nm, the flexibility of the ITO film tends to decrease. As a result, if the film thickness is thick, it may crack when stress is applied. The sheet resistance of the electrode is preferably as low as possible, preferably 10 Ω / □ or less. The electrode may be a single-layer structure or a multi-layer structure in which layers composed of materials with different work functions are stacked.

[0018] When electrodes are formed adjacent to an electron transport layer, it is preferable to use a material with a low work function as the electrode material. Examples of materials with a low work function include alkali metals and alkaline earth metals. Specifically, these include Li, In, Al, Ca, Mg, Sm, Tb, Yb, Zr, Na, K, Rb, Cs, Ba, and their alloys. Alternatively, an alloy may be used of a metal selected from the aforementioned materials with a low work function and a metal with a relatively high work function selected from gold, silver, platinum, copper, manganese, titanium, cobalt, nickel, tungsten, tin, etc. Examples of alloys that can be used as electrode materials include lithium-aluminum alloy, lithium-magnesium alloy, lithium-indium alloy, magnesium-silver alloy, calcium-indium alloy, magnesium-aluminum alloy, indium-silver alloy, calcium-aluminum alloy, etc. When using such metallic materials, the electrode film thickness is preferably 1 nm to 500 nm, and more preferably 10 nm to 300 nm. If the film thickness is thinner than the range mentioned above, the resistance may become too high, preventing sufficient transfer of the generated charge to the external circuit. If the film thickness is too thick, the deposition of the electrode takes a long time, causing the material temperature to rise and potentially damaging other materials and degrading their performance. Furthermore, the large amount of material used increases the occupancy time of the deposition equipment, which can lead to increased costs.

[0019] Organic materials can also be used as electrode materials. For example, polythiophene polymers such as polyethylenedioxythiophene (hereinafter sometimes referred to as PEDOT) are preferred. Such polythiophene polymers are commercially available, and examples include Clevios PH 500, Clevios PH, Clevios P ​​VP Al 4083, and Clevios HIL 1,1 (all trade names, manufactured by Starck). The work function of PEDOT is 4.4 eV, but the work function of the electrode can be adjusted by combining it with other materials. For example, by mixing PEDOT with polystyrene sulfonate (hereinafter sometimes referred to as PSS), the work function can be adjusted to a range of 5.0 to 5.8 eV.

[0020] (Photoelectric conversion layer) The photoelectric conversion layer 13 formed according to the embodiment has a perovskite structure. This perovskite structure is one of the crystal structures and refers to the same crystal structure as perovskite. Typically, the perovskite structure consists of ions A, B, and X, and may take on a perovskite structure when ion B is smaller than ion A.

[0021] This crystal structure has a cubic unit cell, with A at each vertex of the cube, B at the body center, and X at each face center of the cube centered on this. In this crystal structure, the octahedron consisting of one B and six X included in the unit cell is easily distorted by the interaction with A and undergoes a phase transition to a symmetric crystal. It is presumed that this phase transition dramatically changes the physical properties of the crystal, electrons or holes are emitted outside the crystal, and power generation occurs.

[0022] When the film thickness of the photoelectric conversion layer is increased, the light absorption amount increases and the short - circuit current density (Jsc) increases. However, as the carrier transport distance increases, the loss due to deactivation tends to increase. Therefore, there is an optimal film thickness to obtain the maximum efficiency, and the film thickness is preferably 30 nm to 1000 nm, and more preferably 60 to 600 nm.

[0023] For example, if the thickness of the photoelectric conversion layer is adjusted individually, it is possible to adjust the device according to the embodiment and other general devices so that they have the same conversion efficiency under sunlight irradiation conditions. However, under low - illuminance conditions such as 200 lux, due to the different film qualities, the device according to the embodiment can achieve a higher conversion efficiency than general devices. [[ID=***]]

[0024] (First buffer layer 12 and second buffer layer 14) The first buffer layer 12 and the second buffer layer 14 are sandwiched between the photoelectric conversion element and the first or second electrode. If present, one of these layers functions as a hole transport layer and the other as an electron transport layer. While it is preferable for the photoelectric conversion element to have these layers in order to achieve better conversion efficiency, they are not necessarily required in the embodiment, and either or both of them may not be present.

[0025] An electron transport layer has the function of efficiently transporting electrons. When a buffer layer functions as an electron transport layer, it is preferable that this layer contains either a halogen compound or a metal oxide. Suitable examples of halogen compounds include LiF, LiCl, LiBr, LiI, NaF, NaCl, NaBr, NaI, KF, KCl, KBr, KI, or CsF. Of these, LiF is particularly preferred.

[0026] Suitable examples of metal oxides include titanium oxide, molybdenum oxide, vanadium oxide, zinc oxide, nickel oxide, lithium oxide, calcium oxide, cesium oxide, and aluminum oxide. Of these, titanium oxide is preferred. As titanium oxide, amorphous titanium oxide obtained by hydrolysis of titanium alkoxide by the sol-gel method is preferred. Inorganic materials such as metallic calcium can also be used for the electron transport layer.

[0027] When an electron transport layer is provided in the photoelectric conversion element according to the embodiment, the thickness of the electron transport layer is preferably 20 nm or less. This is because it lowers the film resistance of the electron transport layer and increases the conversion efficiency. On the other hand, the thickness of the electron transport layer can be 5 nm or more. By providing an electron transport layer and setting it to a certain thickness or more, the hole blocking effect can be fully exerted, preventing the generated excitons from being deactivated before they emit electrons and holes. As a result, current can be extracted efficiently.

[0028] A hole transport layer is a layer that efficiently transports holes. When a buffer layer functions as a hole transport layer, this layer may contain p-type or n-type organic semiconductor materials. A p-type organic semiconductor can be used as the material for the hole transport layer. Preferably, the p-type organic semiconductor includes a copolymer consisting of a donor unit and an acceptor unit. Examples of donor units include fluorene and thiophene. Examples of acceptor units include benzothiadiazole. Specifically, polythiophene and its derivatives, polypyrrole and its derivatives, pyrazoline derivatives, arylamine derivatives, stilbene derivatives, triphenyldiamine derivatives, oligothiophene and its derivatives, polyvinylcarbazole and its derivatives, polysilane and its derivatives, polysiloxane derivatives having aromatic amines in the side chain or main chain, polyaniline and its derivatives, phthalocyanine derivatives, porphyrin and its derivatives, polyphenylene vinylene and its derivatives, polythienylene vinylene and its derivatives, benzodithiophene derivatives, thieno[3,2-b]thiophene derivatives, etc. These materials may be used in combination for the hole transport layer, or a copolymer consisting of the copolymers constituting these materials may be used. Of these, polythiophene and its derivatives are preferred because they possess excellent stereoregularity and relatively high solubility in solvents.

[0029] In addition, derivatives such as poly[N-9'-heptadecanyl-2,7-carbazole-alto-5,5-(4',7'-di-2-thienyl-2',1',3'-benzothiadiazole)] (hereinafter sometimes referred to as PCDTBT) which is a copolymer containing carbazole, benzothiadiazole, and thiophene, may be used as the material for the hole transport layer. Furthermore, copolymers of benzodithiophene (BDT) derivatives and thieno[3,2-b]thiophene derivatives are also preferred. For example, poly[[4,8-bis[(2-ethylhexyl)oxy]benzo[1,2-b:4,5-b']dithiophene-2,6-diyl][3-fluoro-2-[(2-ethylhexyl)carbony [L]thieno[3,4-b]thiophenediyl]] (hereinafter sometimes referred to as PTB7), and PTB7-Th (sometimes called PCE10 or PBDTTT-EFT), which has a thienyl group that is less electron-donating than the alkoxy group of PTB7, are also preferred. Furthermore, metal oxides can be used as the material for the hole transport layer. Suitable examples of metal oxides include titanium oxide, molybdenum oxide, vanadium oxide, zinc oxide, nickel oxide, lithium oxide, calcium oxide, cesium oxide, and aluminum oxide. These materials have the advantage of being inexpensive. Furthermore, thiocyanates such as copper thiocyanate may be used as the material for the hole transport layer.

[0030] Furthermore, transport materials such as spiro-OMeTAD can be used as dopants for these semiconductor materials. Suitable dopants include oxygen, 4-tert-butylpyridine, lithium-bis(trifluoromethanesulfonyl)imide (Li-TFSI), acetonitrile, tris[2-(1H-pyrazole-1-yl)pyridine]cobalt(III)tris(hexafluorophosphate) salt (commercially available under the trade name "FK102"), tris[2-(1H-pyrazole-1-yl)pyrimidine]cobalt(III)tris[bis(trisfluoromethylsulfonyl)imide](MY11), etc.

[0031] (Method of manufacturing a photoelectric conversion element) The manufacturing method of the photoelectric conversion element 10 according to this embodiment is characterized by the manufacturing of the photoelectric conversion layer 13, while other parts can be manufactured using the same methods as conventional photoelectric conversion elements. The manufacturing method of the photoelectric conversion element according to this embodiment will be described below.

[0032] First, a first electrode 1 is formed on the substrate 16. The method for manufacturing the electrode is appropriately selected depending on the material used and the intended application of the photoelectric conversion element. However, generally, the first electrode can be formed by a method selected from methods such as vacuum deposition, sputtering, ion plating, plating, and coating. For example, when forming a transparent electrode made of ITO or FTO, the electrode is generally formed by the coating method. When forming an opaque electrode, vacuum deposition or sputtering is often used.

[0033] After the electrode 11 is formed, a first buffer layer 12 is formed as needed. The buffer layer 12 is generally formed by a coating method such as spin coating. A coating solution is prepared by dissolving or dispersing the materials constituting the buffer layer, and after filtering as needed, the buffer layer is formed by a coating method under conditions that result in the desired thickness. After coating, it is preferable to dry the layer by heating at a temperature of, for example, 50 to 100°C for 1 to 10 minutes. At this time, it is also preferable to induce a hydrolysis reaction depending on the type of material.

[0034] For example, a thin film of titanium dioxide can be formed as a buffer layer. In this case, a titanium diisopropoxide bis(acetylacetonate) solution is applied as the coating solution by spin coating, and then the hydrolysis reaction is promoted by firing at, for example, 400°C, to form a buffer layer made of titanium dioxide.

[0035] Next, a photoelectric conversion layer 13 is formed. The photoelectric conversion layer is formed either directly on the first electrode 11 or indirectly via the buffer layer 12. The photoelectric conversion layer is formed from a solution containing a perovskite structure precursor compound. Here, the perovskite structure precursor is not particularly limited as long as it can form a perovskite structure by coating and drying, and can be selected from any conventionally known compounds. An example of such a precursor is a perovskite-type compound that can be represented by the general formula (1). As a precursor, a combination of compounds that can form the structure of general formula (1) can be used, for example, a combination of AX and BX2. In this case, the mixing ratio of BX2 to AX is preferably 1:0.5 to 1:4 in molar ratio. Preferably, 1:3 is more preferable. AX is generally a monoalkylammonium halide, for example, methylammonium iodide, methylammonium bromide, methylammonium chloride, ethylammonium iodide, etc. BX2 is generally a lead or tin halide, for example, lead iodide, tin iodide, lead bromide, tin bromide, lead chloride, and tin chloride. In the embodiment, a combination of methylammonium iodide and lead chloride is preferred.

[0036] These precursors are dissolved in an organic solvent capable of dissolving them to form a coating solution. The organic solvent is not particularly limited as long as it can dissolve the precursors, but it can be arbitrarily selected from viewpoints such as ease of drying, cost, and handling. Specifically, N,N-dimethylformamide (hereinafter sometimes referred to as DMF) and γ-butyrolactone (hereinafter sometimes referred to as GBL) can be cited as preferred.

[0037] The concentration of the coating solution is appropriately adjusted according to the coating method, the desired film thickness, and other factors. It is preferable to filter the coating solution using a filter or similar device prior to application. The coating method can be arbitrarily selected from conventionally known methods. Specifically, it can be selected from spin coating, dip coating, casting, bar coating, roll coating, wire bar coating, spray coating, dispenser coating, nozzle coating, capillary coating, etc. Alternatively, the photoelectric conversion layer can be formed using a printing method. Specifically, it can be selected from screen printing, gravure printing, flexographic printing, offset printing, gravure-offset printing, inkjet printing, etc.

[0038] The coating film formed by the application process is subsequently dried. In this embodiment, the drying of the coating film is carried out in a drying chamber 41 as illustrated in Figure 2. The drying chamber 41 is equipped with a transport roll 42 for transporting the substrate 31 on which the coating film has been formed, and a hot air fan 43 for heating the space inside the drying chamber 41. A black plating layer is formed on the surface of the transport roll 42. The plating layer of the transport roll 42 is, for example, a black hard chrome plating layer, a nickel plating layer, or an anodized aluminum plating layer. The black plating layer improves durability and increases the infrared radiation intensity. In particular, by arranging multiple transport rolls 42 at equal intervals near the transport path of the substrate 31, improvements in the uniformity and efficiency of the drying process can be expected. The hot air blower 43 blows hot air into the drying chamber 41.

[0039] (A method for continuously applying and drying a coating film) When mass-producing photoelectric conversion elements according to this embodiment, it is preferable to continuously coat a long substrate with the material and then continuously dry it. In this case, the coated and dried substrate is often subsequently wound into a roll. This method is referred to as the roll-to-roll method in this embodiment.

[0040] In the roll-to-roll method, as shown in Figure 2, the photoelectric conversion layer formation method according to the embodiment can be carried out by passing a continuous substrate 31 after coating through the drying chamber 41. At this time, multiple transport rolls 42 are arranged at equal intervals near the transport path in the drying chamber 41. Since the surface of these transport rolls 42 is a black plated layer, they radiate heat from the hot air blown from the hot air heater 43. This enables efficient drying with minimal unevenness.

[0041] The drying method according to this embodiment is shown in the schematic diagram of Figure 2. A perovskite precursor solution is applied to the substrate 31, which has been pulled out from the roll-shaped substrate 31, by a coating mechanism 32. The coated substrate 31 passes through a drying chamber 41 and is wound onto a roll 44. The conveyor roll 42 is a cylindrical metal roll with a black anodized coating on its surface. In addition to improving durability, this black anodized coating has a high infrared radiation intensity around 6 micrometers, which is expected to efficiently dry the precursor solution. [Explanation of Symbols]

[0042] 41...Drying room 42... Conveyor Roll 43... Hot air heater

Claims

1. A drying chamber for drying a substrate coated with a perovskite precursor compound, In the drying chamber, a transport roll is positioned near the transport path of the substrate coated with the precursor compound. It has, The surface of the conveying roll is a black plated layer. A manufacturing device for photoelectric conversion elements.

2. The aforementioned conveying roll has a black anodized coating formed on the surface of a metal roll. A heating device for heating the space inside the drying chamber. The manufacturing apparatus of claim 1, further comprising the present invention.

3. Multiple transport rolls are arranged at equal intervals along the transport path of the substrate coated with the precursor compound. The manufacturing apparatus according to claim 2.

4. A conveying roll for drying perovskite precursor compounds, A conveyor roll with a black plated layer on its surface.

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