Patent Application
20200402725
Embodiments relate to a photoelectric conversion device and a method of manufacturing the photoelectric conversion device.
Perovskite compounds are expected to be applied to photoelectric conversion devices such as a photovoltaic, a light emitting element, and a photosensor. Using the perovskite compounds as, for example, forming materials of active layers of photoelectric conversion devices such as a photovoltaic makes it possible to employ an inexpensive coating method for forming the active layers and the like, and thus enables a great reduction in a formation cost of the active layers and the like. Because of this, a perovskite photovoltaics as a next-generation photovoltaics that cost low and are harmless.
Cells forming a photovoltaic module each have a structure in which an active layer is sandwiched by a substrate electrode and a counter electrode. As the substrate electrode, a conductive oxide not having sufficient conductivity is typically used, and accordingly, as the area of the cell increases, efficiency for extracting generated electric charges to the outside deteriorates more. To solve this, a plurality of strip-shaped cells are formed side by side and the plural cells are connected in series. A series photovoltaic module having the plural cells is formed by the following method, for instance. The substrate electrodes of the respective cells are formed on a transparent substrate. An active layer is formed on the whole surface of the plural substrate electrodes by coating. Parts of the active layer are scribed, whereby grooves from which the substrate electrodes are exposed are formed. Counter electrodes are formed on the active layer having the scribe grooves so as to correspond to the respective cells. At this time, in the scribe groove, the counter electrode of the adjacent cell is filled, so that the counter electrode of the adjacent cell is electrically connected with the substrate electrode exposed to the inside of the scribe groove.
The scribing of the active layer is executed by mechanical scribing using a cutting tool or laser scribing using laser light, for instance. The hard conductive metal oxide layer exists under the soft, viscous, and low-brittleness active layer such as a perovskite compound layer, and thus at the time of scribing the active layer, the active layer is likely to remain in the scribe grooves and on the conductive metal oxide. The active layer, if remaining, increases electrical resistance between the counter electrode of the adjacent cell and the substrate electrode, resulting in deterioration of power conversion efficiency. Increasing a scribing pressure or output power of laser in order to prevent the active layer from remaining is likely to cause a crack or the like in the conductive metal oxide layer. In a case where the substrate as the base of the conductive metal oxide layer is a soft substrate such as a resin substrate, the increase in the pressure especially at the time of the mechanical scribing causes the soft substrate to deform by being pushed by a cutting tool, which is more likely to cause a crack in the conductive metal oxide layer.
In order to prevent the crack of the conductive metal oxide layer while reducing the remaining of the active layer at the time of the scribing, studies are being made on forming a conductive layer under part of the active layer that is to be scribed and scribing the active layer together with a thickness-direction part of the conductive layer. Since the thickness-direction part of the conductive layer which is easy to scribe is scribed together with the active layer, it is possible to reduce the remaining of the active layer. Further, since the easiness of scribe of the active layer is enhanced, it is possible to reduce, for example, a load of an excessive pressure to the conductive metal oxide layer. However, if part of the conductive layer is, for example, mechanically scribed, cutting chips of the conductive layer produced at the time of the scribing may become the residue in the periphery. Such cutting chips of a conductive substance cause a short circuit or the like between the cells. The above circumstances have given rise to a demand for an art to improve electrical connectivity between the adjacent cells (photoelectric conversion parts) by achieving both the reduction of the remaining of the active layer on the substrate electrodes and the prevention of breakage of the substrate electrodes and by inhibiting a short circuit or the like between the cells due to the cutting chips of the conductive substance, at the time of the scribing of the active layer.
In addition, the scribing of the active layer without the conductive layer under the active layer to be scribed can save a manufacturing cost of the conductive layer and a raw material cost thereof.
A photoelectric conversion device, includes a substrate; a first photoelectric conversion element including a first substrate electrode arranged on the substrate, a first active layer arranged on the first substrate electrode, and a first counter electrode arranged on the first active layer; a second photoelectric conversion element including a second substrate electrode arranged on the substrate and physically separated from the first substrate electrode, a second active layer arranged on the second substrate electrode, and a second counter electrode arranged on the second active layer; and a connection including a groove and a conductive portion, the groove penetrating through the second active layer from a surface of the second active layer to expose a surface of the second substrate electrode from the second active layer, the conductive portion including a part of the first counter electrode filled in the groove, and the connection electrically connecting the first counter electrode and the second substrate electrode via the conductive portion. The second active layer is represented by a composition formula: AαBXχ, where A denotes at least one cation selected from the group consisting of monovalent cations, B denotes at least one cation selected from the group consisting of bivalent cations, and X denotes at least one ion selected from the group consisting of monovalent halogen ions; and the second active layer has a first and a second compound layer, the first compound layer containing a first compound satisfying 0.95≤α, and 2.95≤χ, the second compound layer being arranged between the first compound layer and the second substrate electrode, and the second compound layer containing a second compound satisfying α<0.95, and χ<2.95.
Hereinafter, a photoelectric conversion device of an embodiment and a manufacturing method thereof will be described with reference to the drawings. in respective embodiments, substantially the same constituent portions are denoted by the same reference numerals, and explanation thereof is sometimes partially omitted. The drawings are schematic, and the relation of thickness and planer dimension, a thickness ratio of the respective parts, and so on are sometimes different from actual ones. The term indicating a direction such as an upper or lower direction in the explanation, indicates a relative direction when a forming surface of a photoelectric conversion element of a substrate to be described later is faced upward, unless otherwise specified, and is sometimes different from an actual direction based on a gravitational acceleration direction.
An example of the present embodiment includes that: the substrate 2 includes a substrate transparent to light; the substrate electrode 4 includes a substrate electrode transparent to light and formed on the substrate 2; and the transparent substrate and the transparent substrate electrode enables to receive and emit light through the substrate 2. However, another example of the embodiment can include another configurations different from the above configurations. The other example of the embodiment includes: the photoelectric conversion layer 5 is formed on an opaque substrate as the substrate 2; and the substrate electrode 4 includes a transparent substrate electrode formed on the photoelectric conversion layer 5.
The substrate 2 is formed of a material having a light-transmitting property and insulation performance. As the constituent material of the substrate 2, an inorganic material such as non-alkali glass, quartz glass, or sapphire, or an organic material such as polyethylene (PE), polyethylene terephthalate (PET), polyethylene naphthalate (PEN), polyimide, polyamide, polyamide-imide, or a liquid crystal polymer is used. For example, the transparent substrate 2 may be a rigid substrate formed of an inorganic material or an organic material, or may be a flexible substrate formed of an organic material or a very thin inorganic material.
In a case where the photoelectric conversion device 1 of the embodiment is a photovoltaic, the photoelectric conversion layer 5 is irradiated with light through the substrate 2 and the substrate electrode 4. In a case where the photoelectric conversion device 1 is a light emitting element, light generated in the photoelectric conversion layer 5 is emitted through the substrate 2 and the substrate electrode 4. To take the case where the photoelectric conversion device 1 is a photovoltaic, charge separation is caused by the light irradiating the photoelectric conversion layer 5, so that electrons and holes are generated. Out of the electrons and the holes generated in the photoelectric conversion layer 5, for example, the electrons are collected in the substrate electrode 4, and the holes are collected in the counter electrode 6. The functions of the substrate electrode 4 and the counter electrode 6 may be reversed. Hereinafter, these parts will be described.
The substrate electrode 4 is formed of a material having a light-transmitting property and conductivity. As the constituent material of the substrate electrode 4, a conductive metal oxide such as indium oxide, zinc oxide, tin oxide, indium tin oxide (ITO), fluorine-doped tin oxide (FTO), gallium-doped zinc oxide (GZO), aluminum-doped zinc oxide (AZO), indium-zinc oxide (TZO), or indium-gallium-zinc oxide (IGZO) is used. The substrate electrode 4 may be a film stack of a layer formed of any of the aforesaid materials and a metal layer formed of metal such as gold, platinum, silver, copper, cobalt, nickel, indium, or aluminum, or an alloy containing any of these metals, within a range capable of maintaining the light-transmitting property. The substrate electrode 4 is formed by, for example, a vacuum deposition method, a sputtering method, an ion plating method, a CVD method, a sol-gel method, a plating method, a coating method, or the like.
The thickness of the substrate electrode 4 is not particularly limited, but is preferably not less than 10 nm nor more than 1 μm, and more preferably not less than 30 nm nor more than 300 nm. When the substrate electrode 4 is too thin, sheet resistance becomes high. When the film thickness of the substrate electrode 4 is too thick, light transmittance decreases, and further flexibility decreases, so that a crack or the like is likely to occur due to a stress. It is preferable to select the film thickness of the substrate electrode 4 so that high light transmittance and low sheet resistance are both obtained. The sheet resistance of the substrate electrode 4 is not particularly limited, but is typically 1000Ω/□ or less, preferably 500Ω/□ or less, and more preferably 200Ω/□ or less.
Each layer of the photoelectric conversion layer 5 is determined in accordance with the type of a module which to the device 1 is applied, the module being selected from a photovoltaics, a light emitting element, or a photosensor.
The counter electrode 6 is formed of a material having conductivity, and in some case, having a light-transmitting property. As the constituent material of the counter electrode 6, metal such as platinum, gold, silver, copper, nickel, cobalt, iron, manganese, tungsten, titanium, zirconium, tin, zinc, aluminum, indium, chromium, lithium, sodium, potassium, rubidium, cesium, calcium, magnesium, barium, samarium, or terbium, an alloy containing any of these, a conductive metal oxide such as an indium-zinc oxide (IZO), or a carbon material such as graphene or carbon nanotube is used, for example.
The counter electrode 6 is formed by, for example, a vacuum deposition method, a sputtering method, an ion plating method, a sol-gel method, a plating method, a coating method, or the like. The thickness of the counter electrode 6 is not particularly limited, but preferably is not less than 1 nm nor more than 1 μm. When the film thickness of the counter electrode 6 is too thin, resistance becomes too high, which may make it impossible to sufficiently transmit the generated electric charges to an external circuit. When the thickness of the counter electrode 6 is too thick, its film formation takes a long time and accordingly a material temperature increases, which may damage the active layer 51. Sheet resistance of the counter electrode 6 is not particularly limited, but is preferably 500Ω/□ or less, and more preferably 200Ω/□ or less.
A thickness of the active layer 51 is not limited, but is preferably 10 nm or more and 1000 nm or less. The intermediate layer 52 and the intermediate layer 53 can be arranged as needed, and both or one of them can be omitted in some case.
In the case where the electrons generated in the photoelectric conversion layer 5 are collected in the substrate electrode 4, the intermediate layer 52 is formed of a material capable of selectively and efficiently transporting the electrons. As the constituent material of the intermediate layer 52 functioning as an electron transport layer, an inorganic material such as zinc oxide, titanium oxide, or gallium oxide, an organic material such as polyethyleneimine or its derivative, or a carbon material such as the aforesaid fullerene derivative is used, and the constituent material is not particularly limited.
In the case where the holes are collected in the substrate electrode 4, the intermediate layer 52 is formed of a material capable of selectively and efficiently transporting the holes. As the constituent material of the intermediate layer 52 functioning as a hole transport layer, an inorganic material such as nickel oxide, copper oxide, vanadium oxide, tantalum oxide, or molybdenum oxide, or an organic material such as polythiophene, polypyrrole, polyacetylene, triphenylenediaminepolypyrrol, polyaniline, or a derivative of any of these is used, and the constituent material is not particularly limited.
In the case where the holes generated in the photoelectric conversion layer 5 are collected in the counter electrode 6, the intermediate layer 53, that is, the intermediate layer 531 and the intermediate layer 532 are formed of a material capable of selectively and efficiently transporting the holes. The constituent material of the intermediate layer 53 functioning as the hole transport layer is the same as the constituent material of the intermediate layer 52. In the case where the electrons are collected in the counter electrode 6, the intermediate layer 531 and the intermediate layer 532 are formed of a material capable of selectively and efficiently transporting the electrons. The constituent material of the intermediate layer 53 functioning as the electron transport layer is the same as the constituent material of the intermediate layer 52.
The intermediate layers 531, 532 are formed by, for example, a vacuum deposition method, a sputtering method, an ion plating method, a CVD method, a sol-gel method, a plating method, a coating method, or the like. The intermediate layers 531, 532 each preferably have a thickness of not less than 1 nm nor more than 20 nm.
The active layer 51 is represented by a composition formula: AαBXχ. In the composition formula: AαBXχ, A denotes at least one cation selected from the group consisting of monovalent cations, B denotes at least one cation selected from the group consisting of bivalent cations, and X denotes at least one ion selected from the group consisting of monovalent halogen ions. Examples of A include an organic amine compound such as CH3NH4, cesium (Cs), and rubidium (Rb). Examples of B include lead (Pb) and tin (Sn). Examples of X include halogens such as iodine (I), bromine (B), and chlorine (Cl). The material of each of A, B, and X sites can include not only one material but also a plurality of materials. A material example of X include the combination of iodine and bromine. Further, the combination of the elements is to set the total thereof to satisfy the composition formula: AαBXχ. If the material of X include a combination of iodine and bromine, the active layer 51 is represented by a composition formula: ABIIBrII. When χ is set to 3, the formula is to satisfy I+II=3. An example of the composition formula is described below so that the composition formula is set to ABX3, in which each of A, B, and X sites includes a combination of the materials.
(CH3NH3)0.5Cs0.5Pb0.5Sn0.5I1.5Br1.5 Composition formula:
As illustrated in
At least a part of the unreacted compound layer 512 or at least a part of the partially reacted compound layer 513 is provided between the perovskite compound layer 511 and the substrate electrode 4. The active layer 51 can also have a crystal grain boundary 510 between crystals of compounds. A conductive portion including a part of the counter electrode 6 can penetrate the unreacted compound layer 512 or the partially reacted compound layer 513 to be electrically connected to the substrate electrode 4. The structure of the active layer 51 is not limited to the structures illustrated in
The perovskite compound layer 511 contains a perovskite compound. Examples of the perovskite compound include a compound represented by a composition formula: ABX3. This compound can have a composition represented by a composition formula: AαBXχ and satisfying 0.95≤α, and 2.95≤χ.
The perovskite compound preferably include a three-dimensional perovskite crystal. It is empirical knowledge that a three-dimensional perovskite crystal is obtained and high power conversion efficiency is obtained in a case where a tolerance factor t expressed by the following expression is within a range of not less than 0.75 nor more than 1.1. In the following expression, a Shannon ionic radius is used, though there are several kinds of ionic radii.
t=(A site ionic radius+X site ionic radius)/{21/2×(B site ionic radius+X site ionic radius)}
The unreacted compound layer 512 contains an unreacted compound. Examples of the unreacted compounds include a compound having a composition represented by the composition formula: AαBXχ and satisfying α≈0 and χ≈2. This composition corresponds to a composition represented by a composition formula: BX2.
The partially reacted compound layer 513 contains a partially reacted compound. Examples of the partially reacted compound include a compound having a composition represented by the composition formula: AαBXχ and satisfying 0<α<0.95 and 2<χ<2.95. The composition preferably satisfies 0.2<α<0.4 and 2.2<χ<2.4.
Method examples of forming the active layer 51 include evaporating a perovskite compound or its precursor in a vacuum, applying a solution containing a perovskite compound or its precursor dissolved in a solvent and then heating and drying it. Examples of the precursor include a mixture of methylammonium halide and lead halide or a mixture of methylammonium halide and tin halide.
As the active layer 51, a stacked structure including the layer 511 and at least one selected from the group consisting of the layers 512 and 513 is preferably formed by a so-called two-step method. The two-step method includes a first step of forming a BX2 compound layer and a second step of supplying an AX compound onto the BX2 compound layer to react with each other and thus form an ABX3 layer (perovskite compound layer). The method examples of forming the active layer 51 also include vacuum evaporation, or applying a solution and then heating and drying.
The use of such methods can adjust a supply amount of the AX compound, and a reaction time and a reaction rate between the BX2 compound layer and the AX compound to simply form the stacked structure. For example, when a less AX compound is subjected to vacuum evaporation on the BX2 compound layer, a part thereof is reacted to form the perovskite compound layer 511, and the remainder thereof forms the unreacted compound layer 512 or the partially reacted compound layer 513. An another method example includes dissolving the AX compound into a solution ant then contact the AX compound onto the BX2 compound layer for a short period of time, to reduce a reaction time, resulting in reacting a part thereof to form the perovskite compound layer 511, and the remainder thereof forms the unreacted compound layer 512 or the partially reacted compound layer 513.
As another method example of forming the active layer 51, there can be cited a method in which the perovskite compound layer 511 is once formed, and then heat treatment is performed thereon to selectively volatilize the A site material and the X site material, to form a stacked structure including the perovskite compound layer 511 and at least one of the unreacted compound layer 512 and the partially reacted compound layer 513.
To apply the two-step method using the solution containing the precursor dissolved therein, method examples of coating the solution include a coating method using a meniscus coating apparatus as illustrated in
The coating apparatus 100 illustrated in
A thickness of a solution film of the coating solution 103 can be adjusted in response to parameters such as a gap (Coating Gap) between the coating object 10 and the coating head 102, and a relative speed between the transfer stage 101 and the coating head 102 (Coating Speed).
The following description is about an example of the two-step method using the meniscus coating method. This method example includes: coating a solution containing the dissolved or dispersed BX2 compound and drying it to form the BX2 compound layer; and then coating a solution containing the dissolved or dispersed AX compound onto the BX2 compound layer and drying it. This process causes a reaction between the BX2 compound and the AX compound to partially or completely form of the perovskite compound (ABX3). The partial reaction has a possibility of heating the compound layer to further react the BX2 compound and the AX compound, and alternatively has a possibility of selectively volatilizing the A site and the X site material to cause a reverse reaction (decomposition) of the perovskite compound (ABX3) to reproduce the BX2 compound.
The adjustment of a treatment condition such as a heating condition can form a single structure consisting of the perovskite compound layer 511, a stacked structure including the perovskite compound layer 511 and the unreacted compound layer 512, a stacked structure including the perovskite compound layer 511 and the partially reacted compound layer 513, or a stacked structure including the perovskite compound layer 511, the unreacted compound layer 512, and the partially reacted compound layer 513.
An another method of forming each structure includes adjusting a supply amount of the AX compound to be supplied onto the BX2 compound layer. Method examples of adjusting the supply amount of the AX compound, include adjusting a solid content concentration of the solution containing the dissolved AX compound or the dispersion containing the dispersed AX compound, and adjusting a thickness of the coating solution/dispersion film of the solution/dispersion containing the dissolved/dispersion AX compound.
The following description is about a method of distinguishing the perovskite compound layer 511, the unreacted compound layer 512, or the partially reacted compound layer 513 from them. As described above, when the active layer 51 is represented by the composition formula AαBXχ, the perovskite compound layer 511 has a compound having a composition satisfying 0.95≤α, and 2.95≤χ. The unreacted compound layer 512 has a compound having a composition satisfying α≈0, and χ≈2. The partially reacted compound layer 513 has a compound having a composition satisfying 0<α<0.95, and 2<χ<2.95.
The following description is about a method of calculating α and χ. This method first includes observing a cross section of the active layer 51 with a transmission electron microscope (TEM).
The observed active layer 51 includes a first region and a second region here, the first region being defined by a region arranged on the counter electrode 6 side and having a first contrast, and the second region being defined by a region arranged on the substrate electrode 4 side and having a second contrast brighter than the first contrast. An average signal intensity of the element X in the first region is denoted by X1, an average signal intensity of the element X in the second region is denoted by X2, an average signal intensity of the element B in the first region is denoted by B1, and an average signal intensity of the element B in the second region is denoted by B2. Further, the following value R1 is determined by X1/B1 and the following value R2 is determined by X2/B2. Each of the values X1, X2, B1 and B2 cannot be represented by specific units, namely, it is represented by arbitrary units (arb.units), so that each of the values R1, R2 is also represented by arbitrary units.
R1=X1/B1
R2=X2/B2
One method example of forming the active layer 51 using the two-step method includes forming the BX2 layer, and then coating the AX compound ink onto the layer. This activates a reaction between the BX2 and AX compounds in a surface side of the BX2 layer, namely, the first region side, and thus form a composition of an ABX3 compound, namely, the composition substantially satisfying B:X=1:3. Therefore, the value of R1=X1/B1 represented by arbitrary units can be substantially 3. Accordingly, this is represented by the following formulas.
R1:R2=3: χ
χ=3R2/R1
If the reaction between the BX2 and AX compounds has a reaction rate between A of the AX compound and the BX2 compound and a reaction rate between X of the AX compound and the BX2 compound, both reaction rates being substantially equal, the following formula is satisfied.
α:χ=1:3
Therefore, α and χ can be determined by the following formulas.
α=χ/3
χ=3X2/B2/(X1/B1)
The next description is about a method example of manufacturing a photovoltaic module for describing a method example of manufacturing a photoelectric conversion device of an embodiment. The method example of manufacturing the photovoltaic module includes a plurality of steps for patterning a photoelectric conversion layer 5.
As illustrated in
Next, as illustrated in
Next, as illustrated in
Next, as illustrated in
Next, as illustrated in
The next description is about a method example of manufacturing the photoelectric conversion device 1 for describing a method example of manufacturing a photoelectric conversion device of an embodiment. Although the method example of manufacturing the photoelectric conversion device of the embodiment can be preferably applied for all steps of patterning the photoelectric conversion layer 5 illustrated in
Next, as illustrated in
As illustrated in
An example of common manufacturing steps includes exposing surfaces of the substrate electrodes 4B, 4C in the dividing grooves 11A, 11B, to electrically connect the counter electrodes 6A, 6B of the photoelectric conversion elements 3A, 3B to the substrate electrodes 4B, 4C of the adjacent photoelectric conversion elements 3B, 3C. The dividing grooves 11A, 11B can be formed by mechanical scribing using a cutting tool or laser scribing. When mechanically scribing the photoelectric conversion layer 5X, the application of a pressure for surely exposing the surfaces of the substrate electrodes 4B, 4C, may crack the substrate electrodes 4B, 4C made of a hard and brittle conductive metal oxide. Especially a use of a soft substrate made of an organic material to the substrate 2, may deform the soft substrate pressed by the cutting tool, resulting in further cracking the substrate electrodes 4B, 4C. The use of the soft substrate further may be scribed.
On the other hand, The conventional manufacturing step can lower the pressure in mechanical scribing to prevent the substrate electrodes 4B, 4C from cracking, but this increase the remainder of parts of the photoelectric conversion layer 5X in the dividing grooves 11A, 11B. If the soft and viscous photoelectric conversion layer 5X such as the perovskite compound on the hard substrate electrodes 4B, 4C is tried to be mechanically scribed, parts of the photoelectric conversion layer 5X are likely to remain in the dividing grooves 11A, 11B. If the parts of the photoelectric conversion layer 5X remain in the dividing grooves 11A, 11B, electric resistance (series wiring resistance) between the counter electrodes 6A, 6B of the photoelectric conversion elements 3A, 3B and the substrate electrodes 4B, 4C of the adjacent photoelectric conversion elements 3B, 3C increases, resulting in reducing photoelectric conversion efficiency.
The series wiring resistance between the counter electrodes 6A, 6B of the photoelectric conversion elements 3A, 3B and the substrate electrodes 4B, 4C of the adjacent photoelectric conversion elements 3B, 3C is preferably 5Ω or less, and more preferably 2.5Ω or less. A photovoltaics is determined by irradiating light to obtain an I-V curve and then using the I-V curve to obtain characteristic values such as short-circuit current density Jsc, open circuit voltage Voc, fill factor FF, series resistance Rs, and parallel resistance Rsh. Photoelectric conversion efficiency has a higher value as the series resistance Rs is lower. Since the series resistance Rs includes the series wiring resistance, the series wiring resistance is preferably as low as possible. To obtain practical photoelectric conversion efficiency in a wide variety of applications, the series wiring resistance per unit area is preferably 30 Ω·cm2 or less, and more preferably 15 Ω·cm2 or less. Further, to obtain a generally practical power generation amount in a wide variety of applications, a power generation area needs to be 3 cm2 or more. The series resistance Rs calculated in view of these points is preferably 10Ω or less, and more preferably 5Ω or less. When a ratio occupied by the series wiring resistance in the series resistance Rs is aimed to be reduced to half or less, the series wiring resistance is preferably 5Ω or less, and more preferably 2.5Ω or less. The above series wiring resistance can be achieved by applying the following method of forming the scribe grooves of the embodiment and the scribe grooves based on the method.
The following structure and steps are applied for forming the dividing grooves 11A, 11B, and the connections 13A, 13B in the dividing grooves 11A, 11B, in the method of manufacturing the photoelectric conversion device 1 of the embodiment. The following description is about a step of connecting the photoelectric conversion elements 3 in the method of manufacturing the photoelectric conversion device 1 of the embodiment and the configuration of the connections with reference to
As illustrated in
When the intermediate layer 52 is formed under the active layer 51X, the dividing groove 11A can form three kinds of structures. As illustrated in
When the intermediate layer 53 is formed on the active layer 51X, the dividing groove 11A is formed by scribing a multilayer film of the active layer 51X and the intermediate layer 53.
In the photoelectric conversion device 1 and the manufacturing method thereof, the active layer 51X is formed to have a stacked structure including the perovskite compound layer 511 and at least one of the unreacted compound layer 512 and the partially reacted compound layer 513. The perovskite compound is soft and has high viscosity. In contrast, the unreacted compound and the partially reacted compound have relatively low viscosity. Therefore, a presence of the unreacted compound layer 512 or the partially reacted compound layer 513 between the perovskite compound layer 511 and the substrate electrode 4, enables to easy exposure of the surface of the substrate electrode 4 without any residue in the scribing step. Further, the unreacted compound and the partially reacted compound are mechanically slippery due to their low viscosity. This prevents the substrate electrode 4 and the substrate 2 from cracking and scrapping even hard setting a scribing blade on the unreacted compound layer 512 or the partially reacted compound layer 513 in the mechanical scribing step. The unreacted compound layer 512 or the partially reacted compound layer 513 is to be provided only to at least a scribe part, to achieve the above effect.
An average thickness of the unreacted compound layer 512 and the partially reacted compound layer 513 is preferably 10 nm or more and 500 nm or less, and more preferably 30 nm or more and 300 nm or less. If the setting surface to the scribing blade has a surface roughness of less than 30 nm, this may increase its forming cost. If the unreacted compound layer 512 or the partially reacted compound layer 513 has an average film thickness of less than 30 nm, this may cause a protrusion of the scribing blade to be directly in contact with the substrate electrode 4 to damage the substrate electrode 4. The unreacted compound layer 512 or the partially reacted compound layer 513 may have the light absorbing property, the charge generating property, and the charge selectivity, each being inferior to those of the perovskite compound layer 511. Therefore, if the average thickness of the unreacted compound layer 512 and the partially reacted compound layer 513 exceeds 300 nm, this cannot overlook the reduction in the photoelectric conversion property.
In the photoelectric conversion device 1 and the manufacturing method thereof, the use of the unreacted compound layer 512 or the partially reacted compound layer 513 having the low viscosity, weakens the adhesion force SP1 between the substrate electrode 4 and the unreacted compound layer 512 or between the substrate electrode 4 and the partially reacted compound layer 513. This can remove the unreacted compound layer 512 or the partially reacted compound layer 513 from an interface between the layer and the substrate electrode 4 weakened in the adhesion force SP1, and thus expose the surface of the substrate electrode 4 without any residue in mechanically scribing the active layer 51X with the scribing blade 20. Therefore, this enhances electrical connectivity between the counter electrode 6A of the photoelectric conversion element 3A and the substrate electrode 4B of the photoelectric conversion element 3B. Further, the weakness of the adhesion force SP1 between the substrate electrode 4 and the unreacted compound layer 512 or the partially reacted compound layer 513, improve the scribability of the laser scribing. This enhances electrical connectivity between the counter electrode 6A of the photoelectric conversion element 3A and the substrate electrode 4B of the photoelectric conversion element 3B.
Next, as illustrated in
The photoelectric conversion device 1 and the manufacturing method thereof, can prevent a part of the active layer 51 from remaining in the dividing groove 11 without cracking the substrate electrode in the scribing. Therefore, this can improve electrical connectivity between the adjacent photoelectric conversion elements 3. Concretely, This can reduce electrical resistance of the connection 13A connecting the counter electrode 6A of the photoelectric conversion element 3A and the substrate electrode 4B of the adjacent photoelectric conversion element 3B, namely, the series wiring resistance, down to 5Ω or less and further 2.5Ω or less, as described above. An increase in the series wiring resistance between the photoelectric conversion elements 3 causes a reduction in photoelectric conversion efficiency of the photoelectric conversion device 1. The photoelectric conversion device 1 and the manufacturing method thereof, can improve the photoelectric conversion efficiency. Even the number of the serially connected photoelectric conversion elements 3 is increased, the reduction of a probability of an increase in the connection resistance between the adjacent photoelectric conversion elements 3, can enhance the photoelectric conversion efficiency as the whole device.
When SP3 is the weakest in
A plurality of 150 nm-thick ITO films were formed as substrate electrodes, on a polyethylene naphthalate (PEN) substrate with a 125 μm thickness. The number of the ITO films formed was eight corresponding to the number of photoelectric conversion elements installed. That is, they were formed so as to correspond to an eight-series module. Next, poly(3,4-ethylenedioxythiophene)/poly(4-styrenesulfonate) (PEDOT/PSS) was formed as an intermediate layer on the substrate electrode side. The film formation of the PEDOT.PSS was performed by using Clevios AI4083 manufactured by Heraeus K.K., with the use of a meniscus coating apparatus.
Next, an active layer was formed by using the meniscus coating apparatus and the two-step method. As a coating solution or dispersion in the first step, one obtained by dissolving or dispersing PbI2 in a mixed solvent of dimethylformamide (DMF) and dimethyl sulfoxide (DMSO) in a 1:1 ratio was used. As a coating solution/dispersion in the second step, one obtained by dissolving/dispersing CH3NH3I (MAI) in isopropyl alcohol (IPA) was used. As a result of performing evaluation separately, a solid film thickness of PbI2 was about 250 nm. A solid content concentration of MAI was set to 0.3 M (molar). After finishing the two-step, heat treatment was performed at 120° C. for 5 minutes, to form the active layer.
Next, as a first intermediate layer on the counter electrode side, PC60BM ([6,6]-phenyl-C61-butyric acid methylester) was deposited. As a solvent of a PC60BM ink, monochlorobenzene was used. After the PC60BM ink was applied, it was naturally dried. Its film thickness was set to about 50 nm.
Next, mechanical scribing was performed. As a scribing tool, an 80 μm-wide cutting tool having a rectangular tip was used. In the mechanical scribing, the scribing tool was pressed by a suspension mechanism using a spring having a predetermined force and was scanned. When a pressure of the scribing tool was within a range of 0.002 to 0.2 mN/μm2, three layers of the PC60BM layer, the active layer, and the PEDOT.PSS layer were scraped with almost no residue, and it was possible to expose the ITO films. Further, the scribing did not go so far as to cause cracking of the ITO films and to scrape the ITO films and the PEN substrate. When the pressure was reduced to 0.001 mN/μm2, the residue was seen at some part. When the pressure was increased to 0.3 mN/μm2, the PEN substrate was also scraped.
Next, as a second intermediate layer on the counter electrode side, BCP (2,9-dimethyl-4,7-diphenyl-1,10-phenanthroline) with an about 20 nm thickness was deposited by vacuum evaporation. Next, as a counter electrode, an about 150 nm-thick film of Ag was formed by vacuum evaporation. By using a common deposition mask on the two layers, eight second intermediate layers and eight counter electrodes were formed corresponding to the number of the photoelectric conversion elements installed. Consequently, an eight-series module structure was formed. An area of one photoelectric conversion element is about 2.8 cm2.
Regarding the aforesaid eight-series photoelectric conversion device module, the resistance of series wiring parts passing through mechanical scribe parts (series wiring resistance) was measured. In the measurement of the series wiring resistance, anode wirings were connected to counter electrode-side contact pads, and cathode wirings were connected to the counter electrodes. When the polarity was reversed, substantially the same values were also obtained in all of the following measurement results of the series wiring resistance. When measuring the series wiring resistance, the wiring positions are preferably set at positions as close to the series wiring parts as possible, so as not to be influenced by a sheet resistance of the substrate electrode and the counter electrode as much as possible.
The series wiring resistance at eight places of the eight-series module was measured. In the photoelectric conversion device module of the example 1, the series wiring resistance was 0.3 Ω at all of eight places, when the pressure of the scribing tool was within a range of 0.002 to 0.2 mN/μm2. This value is a low and thus favorable value giving almost no adverse effect on photoelectric conversion efficiency in the operation as practical photovoltaics in a wide variety of applications as previously described. As described above, a favorable photoelectric conversion device module with a low series wiring resistance was obtained.
When a cross section of the produced module was observed by TEM, two kinds of compounds with different contracts existed in the active layer, as illustrated in
When an element analysis of the active layer was performed by using the aforementioned method, it was confirmed that, when a composition ratio of the compound layer on the counter electrode side of the active layer was regarded as A:B:X=1:1:3, a composition ratio of the compound layer on the substrate electrode side of the active layer was approximately A:B:X=0:1:2, and thus an unreacted compound layer was formed.
Photoelectric conversion efficiency of the produced photoelectric conversion device module was measured by using a solar simulator providing AM 1.5 G and 1000 W/m2, and the result was 9.6%.
A photoelectric conversion device module was produced in the same manner as in the example 1, except that the solid content concentration of MAI was increased to 0.4 M (molar) in the second step.
When an element analysis of the active layer was performed, it was confirmed that, when a composition ratio of the compound layer on the counter electrode side of the active layer was regarded as A:B:X=1:1:3, a composition ratio of the compound layer on the substrate electrode side of the active layer was approximately A:B:X=0.24:1:2.24, and thus a partially reacted compound layer, different from the unreacted compound layer in the example 1, was formed.
Evaluation results regarding the scribing properties and the series wiring resistance were similar to those of the example 1, and thus a favorable photoelectric conversion device module with a low series wiring resistance was obtained.
When photoelectric conversion efficiency was measured, the result was 12.7%, and thus the property better than that of the example 1 was obtained. Although the compound layer on the substrate electrode side was the unreacted compound layer (BX2) in the example 1, it was the partially reacted compound layer (A0.24BX2.24) in the example 2. The photoelectric conversion property of the photoelectric conversion device module can be considered to depend on the photoelectric conversion property and the series wiring property of a unit cell. Since the series wiring characteristics were similar between the example 1 and the example 2, it can be considered that a difference occurred in the photoelectric conversion property of the unit cell. Concretely, it can be considered that the reason thereof is because the partially reacted compound layer whose composition is closer to that of the perovskite compound layer (ABX3) has a better photoelectric conversion property. More concretely, it can be considered that the reason thereof is because the partially reacted compound layer is superior in terms of the light absorbing property, the charge generating property, and the charge transport selectivity.
A photoelectric conversion device module was produced in the same manner as in the examples 1 and 2, except that the solid content concentration of MAI was increased to 0.42 M (molar) in the second step.
When an element analysis of the active layer was performed, it was confirmed that, when a composition ratio of the compound layer on the counter electrode side of the active layer was regarded as A:B:X=1:1:3, a composition ratio of the compound layer on the substrate electrode side of the active layer was approximately A:B:X=0.35:1:2.35, and thus a partially reacted compound layer was formed.
Evaluation results regarding the scribing properties and the series wiring resistance were similar to those of the examples 1 and 2, and thus a favorable photoelectric conversion device module with a low series wiring resistance was obtained. When photoelectric conversion efficiency was measured, the result was 12.9%, which was approximately the same as that of the example 2.
A photoelectric conversion device module was produced in the same manner as in the examples 1 to 3, except that the solid content concentration of MAI was further increased to 0.5 M (molar) in the second step.
When an element analysis of the active layer was performed, it was confirmed that, when a composition ratio of the compound layer on the counter electrode side of the active layer was regarded as A:B:X=1:1:3, a composition ratio of the compound layer on the substrate electrode side of the active layer was approximately A:B:X=0.90:1:2.90, and thus a partially reacted compound layer was formed.
When the series wiring resistance of the series wiring parts at eight places was measured, at a place with the lowest series wiring resistance, the value was 0.3Ω, similarly to the examples 1 to 3, and thus a favorable series wiring was formed. However, there was also a place where the series wiring resistance was 18Ω, so that the scribing properties were somewhat lowered when compared to the examples 1 to 3.
When photoelectric conversion efficiency was measured, the result was 10.7%, and thus it was possible to obtain conversion efficiency at a practical level as a photovoltaics.
A photoelectric conversion device module was produced in the same manner as in the examples 1 to 4, except that the solid content concentration of MAI was further increased to 0.6 M (molar) in the second step.
When an element analysis of the active layer was performed, it was confirmed that, when a composition ratio of the compound layer on the counter electrode side of the active layer was regarded as A:B:X=1:1:3, a composition ratio of the compound layer on the substrate electrode side of the active layer was approximately A:B:X=0.96:1:2.96, and thus not the unreacted compound layer in the example 1 and the partially reacted compound layer in the examples 2 to 4, but a perovskite compound layer was formed.
Mechanical scribing was performed in the same manner as in the examples 1 to 4. Even when the pressure of the scribing tool was adjusted within a range of 0.001 to 0.2 mN/μm2, the residue was generated, and it was not possible to sufficiently expose the ITO film. Further, when the pressure was increased to 0.3 mN/μm2, the PEN substrate was also scraped.
A series wiring resistance of the photoelectric conversion device module produced through series wiring in a state where the residue was generated, was a high value of 770 to 850Ω, and it was a value apparently exerting an adverse effect when obtaining a favorable photoelectric conversion device module. When photoelectric conversion efficiency was measured, the result was 2.2%, and thus it was not possible to obtain conversion efficiency at a practical level.
A photoelectric conversion device module was produced in the same manner as in the examples 1 to 4 and the comparative example 1, except that the coating method of the perovskite compound layer was changed from the meniscus coating to spin coating and the solid content concentration of MAI was reduced to 0.05 M.
When a cross section of the produced module was observed by TEM, as illustrated in
The mechanical scribing was performed, in which even when the pressure of the scribing tool was adjusted within a range of 0.001 to 0.2 mN/μm2, the residue was generated, and it was not possible to sufficiently expose the ITO film. Further, when the pressure was increased to 0.3 mN/μm2, the PEN substrate was also scraped.
A series wiring resistance of the photoelectric conversion device module produced through series wiring in a state where the residue was generated, was a high value of 520Ω or more, and it was a value apparently exerting an adverse effect when obtaining a favorable photoelectric conversion device module.
When photoelectric conversion efficiency was measured, the result was 0.1%, and thus it was not possible to obtain conversion efficiency at a practical level. It can be estimated that this is because the series wiring resistance is high, and other than that, the solid content concentration of MAI is excessively low, so that the reaction with PbI2 does not occur almost at all and almost all of the active layer is not reacted up to when it is turned into the perovskite compound layer.
The reason why the scribing could not be performed favorably, can be explained by using the aforementioned
A photoelectric conversion device module was produced in the same manner as in the comparative example 2, except that the solid content concentration of MAI was increased to 0.2 M.
When a cross section of the produced module was observed by TEM, two kinds of compounds with different contrasts existed in the active layer, different from the comparative example 2.
When an element analysis of the active layer was performed, it was confirmed that, when a composition ratio of the compound layer on the counter electrode side of the active layer was regarded as A:B:X=1:1:3, a composition ratio of the compound layer on the substrate electrode side of the active layer was approximately A:B:X=0.92:1:2.92, and thus a partially reacted compound layer was formed.
When the series wiring resistance of the series wiring parts at eight places was measured, at a place with the lowest series wiring resistance, the value was 0.3Ω, and thus a favorable series wiring was formed. However, there was also a place where the series wiring resistance was 20Ω. When photoelectric conversion efficiency was measured, the result was 8.5%.
Three kinds of photoelectric conversion device modules were produced in the same manner as in the comparative example 2 and the example 5, except that the solid content concentration of MAI was changed to 0.3, 0.4, and 0.5 M.
When a cross section of each of the produced modules was observed by TEM, there was no difference in contrasts in the active layer. Although
The mechanical scribing was performed, in which even when the pressure of the scribing tool was adjusted within a range of 0.001 to 0.2 mN/μm2, the residue was generated, and it was not possible to sufficiently expose the ITO film. Further, when the pressure was increased to 0.3 mN/μm2, the PEN substrate was also scraped.
A series wiring resistance of the photoelectric conversion device module produced through series wiring in a state where the residue was generated, was a high value of 1200Ω at the lowest, and it was a value apparently exerting an adverse effect when obtaining a favorable photoelectric conversion device module. When photoelectric conversion efficiency was measured, the results was 1.5% at the maximum, and thus it was not possible to obtain conversion efficiency at a practical level.
Based on the results of the comparative examples 2, 3, and the example 5 in each of which the coating method was changed from the meniscus coating to the spin coating, it was found out that the solid content concentration of MAI for obtaining the practical conversion efficiency is approximately 0.05 to 0.2 M, which is a range narrower than a range of 0.3 to 0.5 M being an appropriate range in the case of the meniscus coating.
As described above, although the unreacted compound layer and the partially reacted compound layer can be formed also by the spin coating, in the case of the meniscus coating, the unreacted compound layer and the partially reacted compound layer are likely to be formed even if the solid content concentration of MAI varies in a wider range, which leads to improvement of the scribing properties, resulting in that it was possible to provide the photoelectric conversion device module with high conversion efficiency.
While certain embodiments of the present invention have been described, these embodiments have been presented by way of example only, and are not intended to limit the scope of the inventions. Indeed, the novel embodiments described herein may be embodied in a variety of other forms; furthermore, various omissions, substitutions and changes may be made without departing from the spirit of the inventions. The inventions described in the accompanying claims and their equivalents are intended to cover such forms or modifications as would fall within the scope and spirit of the inventions.
This application is a continuation of prior International Application No. PCT/JP2019/011479 filed on Mar. 19, 2019; the entire contents of all of which are incorporated herein by reference.
| Number | Date | Country | |
|---|---|---|---|
| Parent | PCT/JP2019/011479 | Mar 2019 | US |
| Child | 17013270 | US |
