JP2014192373A - Method for manufacturing organic thin-film solar cell - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a method for manufacturing an organic thin-film solar cell capable of preventing short-circuit of an element due to generation of a burr without needing any additional step.SOLUTION: A method for manufacturing an organic thin-film solar cell includes the steps of: patterning a lower electrode forming layer 32 laminated on a substrate 31; forming a first intermediate layer forming layer 33 on the patterned lower electrode forming layer 32; forming an organic active layer forming layer 38 on the first intermediate layer forming layer 33; and forming a second intermediate layer forming layer 35 on the organic active layer forming layer 38. The total film thickness of the first intermediate layer forming layer 33, the organic active layer forming layer 38, and the second intermediate layer forming layer 35 is not less than 600 nm and not more than 2500 nm.

Description

  The present invention relates to a method for producing an organic thin film solar cell.

  In recent years, organic thin film solar cells have been studied, and it is known that an organic thin film solar cell uses a patterning process in order to form unit cells in the manufacturing process. For example, Patent Documents 1 to 3 describe a process of forming a lower electrode by patterning using laser scribing or the like. However, according to the study by the present inventors, when the lower electrode is patterned using laser scribing or the like, a burr including a lower electrode ranging from several hundred nm to several μm is formed at the processed end of the lower electrode by laser processing. As a result, the lower electrode and the upper electrode are in contact with each other, which causes a short circuit defect in the solar cell element. For such a problem, Patent Document 1 proposes to reduce the thickness of the back metal electrode in order to suppress the generation of burrs that occur after laser scribing in a solar cell using amorphous silicon as a photoelectric conversion layer. ing. In Patent Document 2, it is proposed to increase the speed of laser processing so as not to generate burrs in a thin film solar cell. Further, Patent Document 3 proposes that it is preferable to select a processing condition that suppresses generation of burrs of the metal film after processing of the counter electrode during patterning.

JP-A-2005-116930 JP 2007-005345 A JP 2010-205892 A

  Proposals as described in Patent Documents 1 to 3 in order to prevent a short circuit due to the occurrence of irregularities (burrs) at the pattern edge caused by patterning for forming the lower electrode in the manufacture of the thin film solar cell element However, both methods take some measures at the time of processing. Moreover, since the organic active layer used as a photoelectric converting layer is soft compared with inorganic materials, such as a silicon | silicone, an organic thin film solar cell is easy to receive the influence of the short circuit by a burr | flash. The present invention provides a method for producing an organic thin film solar cell, which can prevent a short circuit of an element due to the generation of burrs without requiring an additional step in the production of the organic thin film solar cell.

The inventors of the present invention have made extensive studies to solve the above problems, and found that the problems can be solved by adjusting the film thickness of each layer when forming each layer constituting the organic thin film solar cell. That is, the gist of the present invention is as follows.
[1] A step of patterning a lower electrode formation layer laminated on a substrate, a step of forming a first intermediate layer formation layer on the patterned lower electrode formation layer, and formation of the first intermediate layer A method for producing an organic thin-film solar cell, comprising: forming an organic active layer forming layer on a layer; and forming a second intermediate layer forming layer on the organic active layer forming layer. The manufacturing method of the organic thin-film solar cell whose sum total of the film thickness of a 1st intermediate | middle layer formation layer, the said organic active layer formation layer, and a said 2nd intermediate | middle layer formation layer is 600 nm or more and 2500 nm or less.
[2] The ratio of the film thickness of the organic active layer formation layer to the sum of the film thicknesses of the first intermediate layer formation layer and the second intermediate layer formation layer is 0.4 or more and 4.0 or less [ 1] The manufacturing method of the organic thin-film solar cell as described in 1].
[3] The method for producing an organic thin-film solar cell according to [1] or [2], wherein the patterning is performed by a laser scribing method.

  According to the present invention, it is possible to provide a method for manufacturing an organic thin-film solar cell in which a short circuit of an element does not occur even if burrs are generated in a patterning process of a lower electrode formation layer.

It is sectional drawing showing the manufacturing method of the organic thin film solar cell (cell) which has a monolithic structure. It is sectional drawing showing the layer structure of an organic thin-film solar cell element. It is sectional drawing showing the laminated constitution of the solar cell using an organic thin film solar cell element.

Hereinafter, although the manufacturing method of the organic thin film photovoltaic cell concerning this invention is demonstrated in detail, showing a specific aspect, it cannot be overemphasized that this invention is not limited to the specific aspect illustrated.
<1. Manufacturing process of organic thin-film solar cells>
The organic thin-film solar cell manufacturing method according to the present invention includes at least a step of patterning a lower electrode forming layer laminated on a substrate, and a first intermediate layer forming layer on the patterned lower electrode forming layer. A step of forming a film, a step of forming an organic active layer forming layer on the first intermediate layer forming layer, and a step of forming a second intermediate layer forming layer on the organic active layer forming layer. .
FIG. 1 shows a manufacturing process of an organic thin-film solar cell having a monolithic structure as one embodiment according to the present invention. The organic thin film solar cell having a monolithic structure is an organic thin film including a lower electrode 32, a first intermediate layer 37, an organic active layer 38, a second intermediate layer 39, and an upper electrode 40 on a substrate 31. A structure in which solar cells (hereinafter sometimes simply referred to as solar cells, solar cell elements, or elements) are connected in series.

  In the present invention, the organic thin-film solar battery cell may be manufactured in a single-wafer type or in a roll-to-roll method. In order to improve productivity, a roll-to-roll It is preferable to manufacture by a system. Hereinafter, with reference to FIG. 1, the manufacturing method of the organic thin-film solar cell which has the monolithic structure which concerns on one embodiment of this invention is demonstrated.

  In the process of FIG. 1A, by patterning a lower electrode formation layer (not shown) laminated on the substrate 31, the open groove 41 can be formed and the lower electrode 32 can be formed. In the present invention, the lower electrode formation layer means a layer before patterning for forming the lower electrode 32.

  The width of the open groove 41 is usually 5 μm or more, preferably 10 μm or more, more preferably 30 μm or more, and usually 1000 μm or less, preferably 500 μm or less, more preferably 300 μm or less, and even more preferably 100 μm or less. Although there is no special restriction | limiting in the patterning method for forming the open groove 41, The photolithographic method or the laser scribing method is mentioned. In the photolithography method, a lower electrode formation layer is formed on a substrate 31 by a vacuum method such as sputtering or vapor deposition, and a multilayer thin film formed by forming a resist layer thereon is passed through a photomask having a predetermined pattern. The resist layer is exposed to light. This is developed and post-baked to transfer the photomask pattern to the resist layer, and the portion of the lower electrode formation layer not covered with the resist is removed by an etching method, and finally the residual resist layer is removed. In this way, a desired pattern is obtained.

  On the other hand, since the laser scribing method can be finely processed as compared with the photolithography method, it is easy to manufacture an organic thin film solar cell with a higher aperture ratio. However, when the laser scribing method is used, droplets of the lower electrode 32 adhere to the periphery of the processed portion, and the generated burrs tend to be larger than in the photolithography method. When this burr is positioned in the vertical direction with respect to the substrate 31, the first intermediate layer 37, the organic active layer 38, and the second intermediate layer 39, which will be described later, break through and come into contact with the upper electrode 40. May be short-circuited. Furthermore, in order to prevent the droplets of the lower electrode 32 from reattaching to the surface of the substrate 31, a method of removing dust from the substrate 31 or reprocessing can be considered, but there is a problem in terms of throughput. However, in the present invention, even if a large burr occurs, the first intermediate layer 37, the organic active layer 38, and the second intermediate layer 39, which will be described later, are formed with specific film thicknesses. Further, it is possible to prevent a short circuit of the element without requiring a detailed laser scribe condition change or an additional process. Therefore, in the present invention, it is preferable to pattern the lower electrode formation layer by a laser scribing method from the viewpoint that an organic thin-film solar cell having a high aperture ratio can be provided while preventing a short circuit of the element. Hereinafter, the laser scribing method will be described.

The laser light source used in the laser scribing method is not particularly limited, and is a CO ₂ laser (wavelength 9.3 to 10.6 μm), a YAG laser (fundamental wavelength 1064 nm, second harmonic wavelength 532 nm, third harmonic wave). 355 nm, fourth harmonic wavelength 266 nm), YLF, YAP, YVO 4 laser, and excimer laser (XeCl wavelength 308 nm, KrF wavelength 248 nm, ArF wavelength 193 nm), and the like. These lasers can be wavelength-converted as necessary and used in the wavelength range of the present invention. Among these, YAG laser, YVO4 laser, YLF laser, excimer laser and the like are preferable. Of these, a YAG laser or a YVO4 laser is more preferable. The reason is that various types of oscillators are distributed for industrial use, and cost performance is good (the oscillators are relatively cheap and easy to handle).

The energy density of the laser used for the laser scribing is usually 0.1 J / cm ² or more, preferably 0.4 J / cm ² or more. The upper limit is usually 2 J / cm ² or less, preferably 1 J / cm ² or less. When the energy density is equal to or higher than the lower limit, workability is improved, and when the energy density is equal to or lower than the upper limit, damage can be suppressed. The depth of focus of the laser used for laser scribing is usually 50 μm or more, preferably 100 μm or more. On the other hand, the upper limit is usually 1000 μm or less, preferably 800 μm or less. The depth of focus refers to a range in which spot diameters formed when laser light is condensed are considered to be the same optical diameter. If the focal range is within the above range, the layer to be processed can be processed more selectively, and damage to other layers can be avoided. Although the depth of focus is determined by the optical system, it is possible to avoid the complexity of fixing the work material when the value of the depth of focus is above the lower limit, and the optical system becomes complicated when it is below the upper limit. Can be avoided.

  The laser shot overlap rate of the laser used for laser scribing is usually 75% or less, preferably 60% or less, and more preferably 50% or less. The lower limit is not particularly limited, but is usually 5% or more, preferably 3% or more, and more preferably 0% or more. The overlap ratio of the laser shot means a ratio of overlapping the next spot on the spot irradiated immediately before when processing into a line shape using a laser. When a line segment parallel to the processing direction in the laser spot and passing through the center of the laser spot overlaps the spot irradiated immediately before, the ratio of the length of the overlapped line segment is shown. In the case of a rectangular laser spot, the ratio is a ratio when the laser processing direction and one side of the rectangle are parallel to each other. The smaller the overlap rate, the more efficient processing can be performed with a smaller number of irradiations. It is preferable because the processing speed can be secured by the overlap rate being equal to or less than the upper limit. Generation | occurrence | production of a non-processed part can be suppressed because an overlap rate is more than a minimum.

  The pulse width of the laser used for laser scribing is usually 0.1 nanoseconds or more, preferably 1 nanoseconds or more, and the upper limit is usually 500 nanoseconds or less, preferably 50 nanoseconds or less. The repetition frequency is usually 1 kHz or more, preferably 5 kHz or more, and the upper limit is usually 1000 kHz or less, preferably 200 kHz or less. These ranges are the ranges that are usually implemented, but the repetition frequency can be implemented outside the above ranges depending on the required processing energy and the required processing speed.

  The beam shape of the laser used in the present invention is not particularly limited, and examples thereof include a circle, an ellipse, and a rectangle, but a rectangle is preferable. The beam shape means a beam shape on a plane orthogonal to the laser irradiation axis. By making the beam shape rectangular, it is possible to reduce the overlapping rate when the lasers are overlapped and irradiate, and to perform processing efficiently. The rectangle includes a rectangle and a square, and also includes a substantially rectangle with rounded corners. The rectangle includes those that can be equated with the rectangle from the viewpoint of the effect. As a method of making the beam shape rectangular, a known method can be used. The beam shape can be made rectangular using a rectangular core fiber, an aspheric lens, a multi-lens array, a waveguide, a hologram, or the like. As the size of the rectangular beam shape, the length of one side is usually 5 μm or more, preferably 20 μm or more, and the upper limit is usually 500 μm or less, preferably 200 μm or less.

  Further, the energy distribution of the laser used in the present invention is not particularly limited, and examples thereof include a Gaussian distribution, a flat (also referred to as a top hat or a top flat), and the middle thereof, but a flat is preferable. The energy distribution means an intensity distribution in a beam spot formed in the irradiation surface. The flat energy distribution means that the energy intensity difference between the central portion and the outer edge portion is 0% or more and 15% or less, preferably 10% or less. As a method for flattening the energy distribution, a known method can be used. For example, the beam may be rearranged and homogenized using an aspheric lens or the like, or the beam may be overlapped and homogenized using a multi-lens array, a waveguide, a hologram, or the like. Further, a rectangular core fiber or the like may be used. By using a laser with a flat energy distribution, damage to layers other than the processing target layer can be reduced.

  In the patterning by laser scribing used in the present invention, the laser line width is not particularly limited, but is usually 10 μm or more, preferably 30 μm or more, and is usually 1 mm or less, preferably 200 μm or less. When the patterning line width is 30 μm or more, there is a burr (height of several μm) generated in the vertical direction during patterning in order to maintain a sufficient insulating portion distance between the transparent conductive layers insulated by patterning. Even if lying in the horizontal direction, it is preferable because the possibility of contact and conduction can be kept low. The patterning line width of 200 μm or less is preferable in order to supply an organic thin-film solar cell with a higher aperture ratio that can reduce the amount of splash generated by laser patterning.

  As described above, the lower electrode 32 can be formed by patterning the lower electrode formation layer stacked on the substrate 31.

  Next, as shown in FIGS. 1B and 1C, the first intermediate layer forming layer 33, the organic active layer forming layer 34, and the second intermediate layer forming layer 35 are formed on the lower electrode 32. Films are sequentially formed. In the present invention, the first intermediate layer forming layer 33, the organic active layer forming layer 34, and the second intermediate layer forming layer 35 are a first intermediate layer 37, an organic active layer 38, It means a layer before patterning when the second intermediate layer 39 is formed.

As shown in FIG. 1B, when the first intermediate layer forming layer 33 is formed on the entire surface of the lower electrode 32, the open groove 41 is filled with the material of the first intermediate layer forming layer 33. However, the first intermediate layer 37 may be patterned on the lower electrode 32 using a mask or the like without filling the open groove 41 with the material of the first intermediate layer forming layer 33. The total thickness of the first intermediate layer forming layer 33, the organic active layer forming layer 34, and the second intermediate layer forming layer 35 is not less than 600 nm and not more than 2500 nm. According to the study by the present inventors, when a lower electrode layer forming layer having a film thickness of several hundred nm is patterned, burrs having a size of 500 nm to 2000 nm are generated, but the first intermediate layer forming layer 33, the organic activity By setting the total film thickness of the layer forming layer 34 and the second intermediate layer forming layer 35 within the above range, the generated burrs can be sufficiently coated, and the lower electrode 32 contacts the upper electrode 40 described later. There is nothing to do. Therefore, it can prevent that the organic thin-film solar cell manufactured is short-circuited. In addition, in order to suppress the short circuit of an organic thin film photovoltaic cell more, the sum total of the film thickness of the 1st intermediate | middle layer formation layer 33, the organic active layer formation layer 34, and the 2nd intermediate | middle layer formation layer 35 is 650 nm or more. Preferably, the thickness is 700 nm or more. On the other hand, when an organic thin-film solar battery cell is used, it is 2000 nm or less in order to allow the charge obtained in the organic active layer to reach the electrode efficiently. Preferably, it is 1500 nm or less.

  Further, if the ratio of the total thickness of the first intermediate layer forming layer 33, the organic active layer forming layer 34, and the second intermediate layer forming layer 35 to the height of the generated burrs is too small, the burrs are sufficiently reduced. Since the film cannot be coated, the ratio of the total thickness of the first intermediate layer forming layer 33, the organic active layer forming layer 34, and the second intermediate layer forming layer 35 to the size of the generated burr is 1 0.5 or more, more preferably 1.8 or more, and preferably 2.0 or more, usually 100 or less, 90 or less, and 80 or less. In addition, the height of a burr | flash is the height in the cross-sectional direction (cross section shown in FIG. 1) of a photovoltaic cell.

  In addition, if the ratio of the film thickness of the organic active layer forming layer 34 to the sum of the film thicknesses of the first intermediate layer forming layer 33 and the second intermediate layer forming layer 35 is too small, the burr film generated by the patterning is not good. This may be sufficient, and there may be a large variation in performance when uneven coating occurs when the organic active layer forming layer 34 is formed. Further, in a large area coating method typified by a roll-to-roll method, there is a high possibility that film thickness control will be difficult. On the other hand, when the ratio of the film thickness is too large, efficient light collection in the organic active layer of the organic thin-film solar battery to be manufactured becomes difficult, and the efficiency is likely to decrease. Therefore, the ratio of the film thickness of the organic active layer forming layer 34 to the sum of the film thicknesses of the first intermediate layer forming layer 33 and the second intermediate layer forming layer 35 is preferably 0.4 or more. More preferably, it is more preferably 0.6 or more. On the other hand, it is preferably 4.0 or less, more preferably 3.5 or less, and 3.0 or less. Is particularly preferred.

  Further, if the total thickness of the first intermediate layer forming layer 33, the organic active layer forming layer 34, and the second intermediate layer forming layer 35 is 600 nm or more and 2500 nm or less, the first intermediate layer forming layer 33 The film thickness is not particularly limited, but is usually 20 nm or more, preferably 50 nm or more, particularly preferably 100 nm or more, and is usually 1000 nm or less, preferably 500 nm or less, particularly preferably 300 nm or less. In particular, the film thickness of the first intermediate layer forming layer 33 being 100 nm or more means uneven coating during the formation of the first intermediate layer forming layer 33 or the film formation of the first intermediate layer forming layer 33. It is preferable because the surface defect due to aggregation or the like is less likely to be a device defect, and the thickness of the first intermediate layer forming layer 33 is preferably 300 nm or less because a resistance component during electron transport is suppressed. . Further, it is preferable that light is incident from the lower electrode 32 positioned below the first intermediate layer forming layer 33 because transmitted light increases, film formation costs are reduced, and weight is not increased.

In addition, if the sum of the film thicknesses of the first intermediate layer forming layer 33, the organic active layer forming layer 34, and the second intermediate layer forming layer 35 is within the above range, there is a particular limitation on the film thickness of the organic active layer 38. However, it is usually at least 200 nm, preferably at least 300 nm, particularly preferably at least 400 nm, while it is usually at most 2000 nm, preferably at most 1500 nm, particularly preferably at most 1000 nm. In particular, the film thickness of the organic active layer forming layer 34 being 400 nm or more is due to coating unevenness when the first intermediate layer forming layer 33 is formed, aggregation or the like when the first intermediate layer forming layer 33 is formed. Even if there are surface irregularities, it is difficult to cause element defects, burrs generated by patterning for forming the lower electrode 32, uneven coating of the first intermediate layer forming layer 33, or the first intermediate layer forming layer 33. Even when there are surface irregularities due to agglomeration or the like during film formation, it is preferable because these can be sufficiently coated. Furthermore, in the manufactured organic thin film photovoltaic cell, the donor component and the acceptor component contained in the organic active layer are preferable because they absorb all incident light and generate a sufficient charge. In addition, it is preferable that the thickness of the organic active layer forming layer 34 is 1000 nm or less because the charges generated by the light absorption of the organic active layer 38 sufficiently reach both electrodes, and the material cost can be suppressed. .

  If the sum of the thicknesses of the first intermediate layer forming layer 33, the organic active layer forming layer 34, and the second intermediate layer forming layer 35 is within the above range, the thickness of the second intermediate layer forming layer 35 is Although there is no restriction | limiting, Usually, it is 100 nm or more, Preferably it is 150 nm or more, Most preferably, it is 200 nm, On the other hand, it is 2000 nm or less normally, Preferably it is 1500 nm or less, Most preferably, it is 800 nm or less. In particular, the film thickness of the second intermediate layer forming layer 35 is 200 nm or more, the coating unevenness at the time of forming the first intermediate layer forming layer 33 or the organic active layer forming layer 34, Even when there are surface irregularities due to agglomeration or the like during film formation, it is preferable to prevent element defects and to sufficiently coat patterning burrs generated on the lower electrode 32. Moreover, it is preferable because the peel test strength, the adhesion test strength, and the bending test strength of the organic thin film solar cell are improved. Further, if the thickness of the second intermediate layer forming layer 35 is 800 nm or less, it is preferable to prevent the charge (here, holes) from being a resistance component when moving in the layer, and the material cost can be reduced. And is preferable because the weight does not increase.

The electrical conductivity of the first intermediate layer forming layer 33 is not particularly limited, but is usually 100 S / cm or less, preferably 10 S / cm or less, particularly preferably 1 S / cm or less, while usually 10 ⁻⁸ S. / Cm or more, preferably 10 ⁻⁷ S / cm or more, particularly preferably 10 ⁻⁶ S / cm or more. In particular, the electrical conductivity of the first intermediate layer forming layer 33 being 1 S / cm or less means that leakage current (leakage) or conduction between adjacent first intermediate layers 37 obtained in a process described later is generated. This is preferable because it hardly occurs. Moreover, the electrical conductivity of the first intermediate layer forming layer 33 is 10 ⁻⁶ S / cm or more, which means that the organic thin film solar produced when the second intermediate layer forming layer 35 has the above-described film thickness. In a battery cell, it is preferable in order to prevent it from becoming a resistance component when electric charges (electrons) move in the first intermediate layer.

The carrier mobility of each of the p-type semiconductor and the n-type semiconductor contained in the organic active layer forming layer 34 is not particularly limited, but is usually 10 ⁻⁶ cm / Vs or higher, preferably 10 ⁻⁵ cm / Vs or higher, particularly preferably. 10 ⁻⁴ cm / Vs or more. In particular, the carrier mobility of 10 ⁻⁴ cm / Vs or more means that in the manufactured organic thin film solar cell, holes and electrons obtained by charge separation of excitons generated in the organic active layer are It is preferable because the possibility of reaching the intermediate layer or the second intermediate layer 39 is increased.

The conductivity of the second intermediate layer forming layer 35 is not particularly limited, but is usually 100 S / cm or less, preferably 10 S / cm or less, particularly preferably 1 S / cm or less, while usually 10 ⁻⁸ S / cm. Above, preferably 10 ⁻⁷ S / cm or more, particularly preferably 10 ⁻⁶ S / cm or more. In particular, the electrical conductivity of the second intermediate layer forming layer 35 being 1 S / cm or less means that leakage current is generated between the adjacent second intermediate layers 39 in the manufactured organic thin film solar cell. (Leakage) or conduction is less likely to occur. The electrical conductivity of the second intermediate layer forming layer 35 is 10 ⁻⁶ S / cm or more, which means that the organic thin-film solar cell manufactured when the second intermediate layer forming layer 35 has the above-described film thickness. In FIG. 5, it is possible to prevent the charge (hole) from becoming a resistance component when moving in the second intermediate layer 39.

  Next, as shown in FIG. 1 (d), several numbers are formed in the vicinity of the first intermediate layer forming layer 33, the organic active layer forming layer 34, and the second intermediate layer forming layer 35 so as not to overlap the groove 41. Patterning is performed at a distance of about 10 μm to 1 mm, and an open groove 42 reaching the lower electrode 32 is formed. There is no particular limitation on the patterning method for forming the open groove 42, and a photolithography method and a laser scribing method can be used as in the patterning of the lower electrode formation layer. The width of the groove is usually 5 μm or more, preferably 10 μm or more, more preferably 25 μm or more, further preferably 50 μm or more, and usually 1000 μm or less, preferably 500 μm or less, more preferably 200 μm or less, and even more preferably 100 μm or less. It is. The wavelength of the laser forming the second open groove 42 is usually 200 nm or more, preferably 250 nm or more, and the upper limit is usually 1200 nm or less, preferably 900 nm, more preferably 600 nm or less. Thereby, the 1st intermediate | middle layer 37, the organic active layer 38, and the 2nd intermediate | middle layer 39 can be formed.

  Next, as shown in FIG. 1E, an upper electrode formation layer 36 is formed. The upper electrode layer 36 means a layer before patterning for forming the upper electrode 40. At this time, the open groove 42 is filled with the material of the upper electrode formation layer 36. The open groove 42 is for connecting an upper electrode 40 (to be described later) of the unit cell to the lower electricity 32 of the adjacent unit cell, so that it does not reach a depth reaching the lower electrode 32 of the adjacent unit cell. Don't be. Note that the lower electrode 32 may not exist in the open groove 42.

Thereafter, as shown in FIG. 1 (f), an open groove 43 is formed in the upper electrode formation layer 36, the first intermediate layer 37, the organic active layer 38, and the second intermediate layer 39, and divided into unit cells. The upper electrode 40 can be formed. In addition, the formation method of the open groove 43 is not specifically limited, Methods, such as a photolithographic method and a laser scribing, can be used. Since the open groove 43 divides the upper electrode forming layer 36 of the adjacent unit cell, it may stop in the middle of the organic active layer 38 without penetrating through the organic active layer 38. The lower electrode 32 may be penetrated through the intermediate layer 37. Since the upper electrode 40 of each unit cell is electrically connected to the lower electrode 32 of the adjacent unit cell by the material of the upper electrode 40 filling the inside of the open groove 42, the organic thin film solar cell in which the unit cells are connected in series Is obtained.
Hereinafter, each layer which comprises the said organic thin film photovoltaic cell is demonstrated in detail.

<1-1. Substrate 31>
The substrate 31 serves as a base material for an element configuration formed thereon. The material of the board | substrate 31 is not specifically limited unless the effect of this invention is impaired remarkably. Suitable examples of the material of the substrate 31 include inorganic materials such as quartz, glass, sapphire, and titania; polyethylene terephthalate, polyethylene naphthalate, polyethersulfone, polyimide, nylon, polystyrene, polyvinyl alcohol, ethylene vinyl alcohol copolymer, Fluoropolymer film, polyolefin such as vinyl chloride or polyethylene; organic material such as cellulose, polyvinylidene chloride, aramid, polyphenylene sulfide, polyurethane, polycarbonate, polyarylate, polynorbornene or epoxy resin; paper material such as paper or synthetic paper; stainless steel Examples thereof include composite materials such as those obtained by coating or laminating a surface of a metal such as titanium or aluminum to impart insulation.

Examples of the glass include soda glass, blue plate glass, and non-alkali glass. Among these, alkali-free glass is preferable in that there are few eluted ions from the glass. There is no restriction | limiting in the shape of the board | substrate 31, For example, things, such as plate shape, a film form, or a sheet form, can be used. Moreover, although there is no restriction | limiting in the film thickness of a board | substrate, it is 5 micrometers or more normally, Preferably it is 20 micrometers or more, on the other hand, it is 20 mm or less normally, Preferably it is 10 mm or less. It is preferable that the thickness of the substrate is 5 μm or more because the possibility that the strength of the organic thin film solar cell element is insufficient is reduced. It is preferable that the thickness of the substrate is 20 mm or less because the cost is suppressed and the weight does not increase. When the material of the substrate is glass, the film thickness is usually 0.01 mm or more, preferably 0.1 mm or more, and is usually 1 cm or less, preferably 0.5 cm or less. It is preferable that the thickness of the substrate is 0.01 mm or more because the mechanical strength increases and it is difficult to break. Moreover, it is preferable that the film thickness of the substrate is 0.5 cm or less because the weight does not increase.

<1-2. Lower electrode 32, upper electrode 40>
As described above, the organic thin-film solar battery has a pair of electrodes of a lower electrode 32 and an upper electrode 40 described later. In the present invention, the lower electrode 32 means an electrode arranged at a position close to the substrate 31, and the upper electrode 40 means an electrode arranged at a position farther from the substrate 31 than the lower electrode 32. As shown in FIG. 1, the lower electrode 32 can be formed by patterning the lower electrode forming layer, and the upper electrode 40 can be formed by patterning the upper electrode forming layer 36.

  Usually, one of the pair of electrodes is an anode, and the other electrode is a cathode. In the present invention, when the lower electrode 32 is a cathode, the upper electrode 40 is an anode, and when the lower electrode 32 is an anode, the upper electrode 40 is a cathode. As for the lower electrode 32 and the upper electrode 40, at least one electrode should just have translucency, but both may have translucency. In the present invention, having translucency means that the average light transmittance of sunlight is 40% or more, but in order to make light sufficiently reach the organic active layer 38 described later, The average light transmittance is preferably 70% or more. The average light transmittance can be measured with a normal spectrophotometer.

  The lower electrode 32 and the upper electrode 40 can be formed by the materials and methods described below, specifically, the materials and the like that can be used differ depending on whether they are the anode or the cathode. 32 is a metal oxide, a metal, or an alloy thereof, whether it is a cathode or an anode.

  The anode is an electrode generally made of a conductive material having a work function higher than that of the cathode and having a function of smoothly extracting holes generated in the organic active layer 38.

  Examples of the anode material include metal oxides such as nickel oxide, tin oxide, indium oxide, indium tin oxide (ITO), indium-zirconium oxide (IZO), titanium oxide, indium oxide, and zinc oxide; gold, Examples thereof include metals such as platinum, silver, chromium and cobalt or alloys thereof. These substances are preferable because they have a high work function, and further, a conductive polymer material represented by PEDOT: PSS in which a polythiophene derivative is doped with polystyrene sulfonic acid can be stacked. When laminating such a conductive polymer, the work function of this conductive polymer material is high, so even if it is not a material with a high work function as described above, it is suitable for cathodes such as Al and Mg. Metals can also be widely used. PEDOT: PSS in which a polythiophene derivative is doped with polystyrene sulfonic acid, or a conductive polymer material in which polypyrrole, polyaniline, or the like is doped with iodine or the like can also be used as an anode material. When the anode is a transparent electrode, it is preferable to use a light-transmitting conductive metal oxide such as ITO, zinc oxide or tin oxide, and ITO is particularly preferable.

The film thickness of the anode is not particularly limited, but is usually 10 nm or more, preferably 20 nm or more, and more preferably 50 nm or more. On the other hand, it is usually 10 μm or less, preferably 1 μm or less, more preferably 500 nm or less. When the thickness of the anode is 10 nm or more, the sheet resistance is suppressed, and when the thickness of the anode is 10 μm or less, light can be efficiently converted into electricity without decreasing the light transmittance. When the anode is a transparent electrode, it is necessary to select a film thickness that can achieve both light transmittance and sheet resistance.

The sheet resistance of the anode is not particularly limited, but is usually 1Ω / □ or more, on the other hand, 1000Ω / □ or less, preferably 500Ω / □ or less, more preferably 100Ω / □ or less.
Examples of the anode forming method include a vacuum film forming method such as a vapor deposition method or a sputtering method, or a wet coating method in which an ink containing nanoparticles or a precursor is applied to form a film.

  The cathode is generally composed of a conductive material having a low work function, and is an electrode having a function of smoothly extracting electrons generated in the organic active layer 38. For example, platinum, gold, Metals such as silver, copper, iron, tin, zinc, aluminum, indium, chromium, lithium, sodium, potassium, cesium, calcium or magnesium and their alloys; inorganic salts such as lithium fluoride and cesium fluoride; nickel oxide, oxide Examples thereof include metal oxides such as aluminum, lithium oxide, or cesium oxide. These materials are preferable because they are materials having a low work function. Similarly to the anode, a material having a high work function can be used for the cathode by using an n-type semiconductor such as titania having conductivity as the electron extraction layer. From the viewpoint of electrode protection, the cathode material is preferably a metal such as platinum, gold, silver, copper, iron, tin, aluminum, calcium or indium, or an alloy using these metals such as indium tin oxide.

  The film thickness of the cathode is not particularly limited, but is usually 10 nm or more, preferably 20 nm or more, more preferably 50 nm or more. On the other hand, it is usually 10 μm or less, preferably 1 μm or less, more preferably 500 nm or less. When the film thickness of the cathode is 10 nm or more, the sheet resistance is suppressed, and when the film thickness of the cathode is 10 μm or less, light can be efficiently converted into electricity without decreasing the light transmittance. When the cathode is a transparent electrode, it is necessary to select a film thickness that achieves both light transmittance and sheet resistance.

  The sheet resistance of the cathode is not particularly limited, but is usually 1000Ω / □ or less, preferably 500Ω / □ or less, and more preferably 100Ω / □ or less. Although there is no restriction on the lower limit, it is usually 1Ω / □ or more. As a method for forming the cathode, there are a vacuum film formation method such as a vapor deposition method or a sputtering method, or a wet coating method in which an ink containing nanoparticles or a precursor is applied to form a film.

  Furthermore, the anode and the cathode may have a laminated structure of two or more layers. In addition, characteristics (electric characteristics, wetting characteristics, etc.) may be improved by performing surface treatment on the anode and the cathode.

  After laminating the anode and cathode, the organic thin-film solar cell element is heated in a temperature range of usually 50 ° C. or higher, preferably 80 ° C. or higher, usually 300 ° C. or lower, preferably 280 ° C. or lower, more preferably 250 ° C. or lower. It is preferable to do this (this step may be referred to as an annealing treatment step). By performing the annealing treatment step at a temperature of 50 ° C. or higher, an effect of improving the adhesion between the layers of the organic thin film solar cell element, for example, the adhesion between the electron extraction layer and the cathode and / or the electron extraction layer and the active layer is obtained. Therefore, it is preferable. By improving the adhesion between the layers, the thermal stability and durability of the organic thin film solar cell element can be improved. It is preferable to set the temperature of the annealing treatment step to 300 ° C. or lower because the possibility that the organic compound in the active layer is thermally decomposed is reduced. In the annealing treatment step, stepwise heating may be performed within the above temperature range.

  The heating time is usually 1 minute or longer, preferably 3 minutes or longer, and usually 3 hours or shorter, preferably 1 hour or shorter. The annealing treatment step is preferably terminated when the open-circuit voltage, the short-circuit current, and the fill factor, which are parameters of the solar cell performance, reach a constant value. Further, the annealing treatment step is preferably performed under normal pressure and in an inert gas atmosphere. As a heating method, the organic thin film solar cell element may be placed on a heat source such as a hot plate, or the organic thin film solar cell element may be placed in a heating atmosphere such as an oven. The heating may be performed batchwise or continuously.

<1-3. First intermediate layer 37, second intermediate layer 39>
The first intermediate layer 37 is formed on the lower electrode 32. Usually, when the lower electrode 32 is an anode, the first intermediate layer 37 is a hole extraction layer, and when the lower electrode 32 is a cathode, One intermediate layer 37 is an electron extraction layer. The second intermediate layer 39 means a hole extraction layer or an electron extraction layer formed on the organic active layer 38. When the upper electrode 40 is an anode, the second intermediate layer 39 is a hole. When the upper electrode 40 is a cathode, the second intermediate layer 39 is an electron extraction layer. As shown in FIG. 1, the first intermediate layer 37 can be formed by patterning the first intermediate layer forming layer 33, and the second intermediate layer 39 can be formed by the second intermediate layer. The formation layer 35 can be formed by patterning.

  The electron extraction layer has a function of improving the efficiency of extracting electrons from the organic active layer 38 to the cathode. As long as it has such a function, a material that can be used for the electron extraction layer is not particularly limited, and examples thereof include inorganic compounds and organic compounds.

  Examples of inorganic compound materials include alkali metal salts such as Li, Na, K or Cs; titanium oxide (TiOx), zinc oxide (ZnO), tin oxide (SnOx), niobium oxide (NbOx), or these. Examples thereof include n-type semiconductor metal oxides such as mixed (doped) mixed metal oxides. Among them, the alkali metal salt is preferably a fluoride salt such as LiF, NaF, KF or CsF, and the n-type semiconductor metal oxide is preferably titanium oxide (TiOx) or zinc oxide (ZnO). Although the operation mechanism of such a material is unknown, it is conceivable to reduce the work function of the cathode when combined with a cathode made of Al or the like and increase the voltage applied to the solar cell element.

  Examples of organic compound materials include, for example, phosphine compounds having a double bond between a phosphorus atom and a group 16 element such as triarylphosphine oxide compounds; bathocuproin (BCP) or bathophenanthrene (Bphen), A phenanthrene compound which may have a substituent and may be substituted at the 1-position and the 10-position with a heteroatom; a boron compound such as triarylboron; and (8-hydroxyquinolinato) aluminum (Alq3) Organometallic oxide; Compound having 1 or 2 ring structure which may have a substituent such as oxadiazole compound or benzimidazole compound; Naphthalenetetracarboxylic anhydride (NTCDA) or perylenetetracarboxylic acid Of dicarboxylic anhydrides, such as anhydrides (PTCDA) Aromatic compounds having Unachijimigo dicarboxylic acid structure.

  The LUMO energy level of the material of the electron extraction layer is not particularly limited, but is usually −4.0 eV or more, preferably −3.9 eV or more. On the other hand, it is usually −1.9 eV or less, preferably −2.0 eV or less. It is preferable that the LUMO energy level of the material for the electron extraction layer is −1.9 eV or less because charge transfer can be promoted. It is preferable that the LUMO energy level of the material for the electron extraction layer is −4.0 eV or more in terms of preventing reverse electron transfer to the n-type semiconductor material.

  The HOMO energy level of the material for the electron extraction layer is not particularly limited, but is usually −9.0 eV or more, preferably −8.0 eV or more. On the other hand, it is usually −5.0 eV or less, preferably −5.5 eV or less. The HOMO energy level of the material for the electron extraction layer is preferably −5.0 eV or less from the viewpoint of preventing movement of holes. As a method for calculating the LUMO energy level and the HOMO energy level of the material of the electron extraction layer, a cyclic voltammogram measurement method may be mentioned. For example, it can implement with reference to the method as described in well-known literature (International Publication 2011/016430).

  When the material of the electron extraction layer is an organic compound, the glass transition temperature (hereinafter sometimes referred to as Tg) of this compound as measured by the DSC method is not particularly limited, but is not observed, or It is preferable that it is 55 degreeC or more. That the glass transition temperature is not observed by the DSC method means that there is no glass transition temperature. Specifically, the determination is made based on the presence or absence of a glass transition temperature of 400 ° C. or lower. A material in which the glass transition temperature by the DSC method is not observed is preferable in that it has high thermal stability.

  Among the compounds having a glass transition temperature of 55 ° C. or higher as measured by the DSC method, the glass transition temperature is preferably 65 ° C. or higher, more preferably 80 ° C. or higher, more preferably 110 ° C. or higher, particularly preferably. Compounds that are 120 ° C. or higher are desirable. On the other hand, the upper limit of the glass transition temperature is not particularly limited, but is usually 400 ° C. or lower, preferably 350 ° C. or lower, more preferably 300 ° C. or lower.

  The glass transition temperature in the present specification is defined as a point at which specific heat changes in an amorphous solid, which is a temperature at which local molecular motion is started by thermal energy. When the temperature rises further than Tg, the solid structure changes and crystallization occurs (the temperature at this time is defined as the crystallization temperature (Tc)). When the temperature rises further, it generally melts at the melting point (Tm) and changes to a liquid state. However, these phase transitions may not be observed due to molecular decomposition or sublimation at high temperatures.

  The DSC method is a thermophysical property measurement method (differential scanning calorimetry method) defined in JIS K-0129 “General Rules for Thermal Analysis”. In order to determine the glass transition temperature more clearly, it is desirable to measure after rapidly cooling a sample once heated to a temperature higher than the glass transition temperature. For example, the measurement can be carried out by a method described in a known document (International Publication No. 2011/016430).

  When the glass transition temperature of the compound used for the electron extraction layer is 55 ° C. or higher, the structure of this compound is difficult to change against external stress such as applied electric field, flowing current, stress due to bending or temperature change. It is preferable in terms of durability. Furthermore, since there is a tendency that the crystallization of the thin film of the compound does not proceed easily, the stability of the electron extraction layer is improved by making it difficult for the compound to change between the amorphous state and the crystalline state in the operating temperature range. Therefore, it is preferable in terms of durability. This effect becomes more prominent as the glass transition temperature of the material is higher.

There is no restriction | limiting in the formation method of an electronic taking-out layer. For example, when a material having sublimation property is used, it can be formed by a vacuum deposition method or the like. Further, for example, when a material soluble in a solvent is used, it can be formed by a wet coating method such as spin coating or inkjet. When the electron extraction layer is formed by a coating method, a surfactant may be further contained in the coating solution. By using the surfactant, the occurrence of dents due to adhesion of fine bubbles or foreign matters and / or uneven coating in the drying process is suppressed. Known surfactants (cationic surfactants, anionic surfactants, nonionic surfactants) can be used as the surfactant. Of these, silicon-based surfactants, acetylenic diol-based surfactants, and fluorine-based surfactants are preferable. In addition, as surfactant, only 1 type may be used and 2 or more types may be used together by arbitrary combinations and a ratio.

  Specifically, for example, when an alkali metal salt is used as a material for the electron extraction layer, the electron extraction layer can be formed by using a vacuum film formation method such as vacuum deposition or sputtering. Especially, it is desirable to form an electron taking-out layer by vacuum vapor deposition by resistance heating. By using vacuum deposition, damage to other layers such as an active layer can be reduced. On the other hand, for metal oxides of n-type semiconductors, for example, when zinc oxide ZnO is used as the material for the electron extraction layer, a vacuum film formation method such as sputtering can be used. It is desirable to form the extraction layer. For example, Sol-Gel Science, C.I. J. et al. Brinker, G.M. W. According to the sol-gel method described by Scherer, Academic Press (1990), an electron extraction layer composed of zinc oxide can be formed.

  The hole extraction layer has a function of improving the efficiency of extracting holes from the active layer to the anode. The material that can be used for the hole extraction layer is not particularly limited as long as it has such a function. Specifically, polythiophene, polypyrrole, polyacetylene, triphenylenediamine, polyaniline, and the like, sulfonic acid and / or Conductive polymer doped with iodine, polythiophene derivative having sulfonyl group as a substituent, conductive organic compound such as arylamine, metal oxide such as copper oxide, nickel oxide, manganese oxide, molybdenum oxide, vanadium oxide or tungsten oxide Products, Nafion, p-type semiconductors described later, and the like. Among them, a conductive polymer doped with sulfonic acid is preferable, and (3,4-ethylenedioxythiophene) poly (styrenesulfonic acid) (PEDOT: PSS) in which a polythiophene derivative is doped with polystyrene sulfonic acid is more preferable. It is. A thin film of metal such as gold, indium, silver or palladium can also be used. A thin film of metal or the like may be formed alone or in combination with the above organic material.

  There is no restriction | limiting in the formation method of a positive hole taking-out layer. For example, when a material having sublimation property is used, it can be formed by a vacuum deposition method or the like. For example, when a material soluble in a solvent is used, it can be formed by a wet coating method such as a spin coating method or an ink jet method. When a semiconductor material is used for the hole extraction layer, the precursor may be converted into a semiconductor compound after forming the layer using the precursor, similarly to the low-molecular organic semiconductor compound of the organic active layer described later.

Especially, when using PEDOT: PSS as a material of a hole taking-out layer, it is preferable to form a hole taking-out layer by the method of apply | coating a dispersion liquid. PEDOT: The dispersion of PSS, and CLEVIOS ^TM series of Heraeus, Inc., include Agfa Corp. of ORGACON ^TM series and the like. When the hole extraction layer is formed by a coating method, a surfactant may be further contained in the coating solution. By using the surfactant, the occurrence of dents due to adhesion of fine bubbles or foreign matters and / or uneven coating in the drying process is suppressed. Known surfactants (cationic surfactants, anionic surfactants, nonionic surfactants) can be used as the surfactant. Of these, silicon-based surfactants, acetylenic diol-based surfactants, and fluorine-based surfactants are preferable. In addition, as surfactant, only 1 type may be used and 2 or more types may be used together by arbitrary combinations and a ratio.

<1-4. Organic active layer 38>
The organic active layer 38 refers to a layer in which photoelectric conversion is performed, and usually includes a p-type semiconductor compound and an n-type semiconductor compound. The p-type semiconductor compound is a compound that works as a p-type semiconductor material, and the n-type semiconductor compound is a compound that works as an n-type semiconductor material. Specifically, when the solar cell element receives light, the light is absorbed by the organic active layer 38, electricity is generated at the interface between the p-type semiconductor compound and the n-type semiconductor compound, and the generated electricity is taken out from the electrode. It functions as a solar cell element. The organic active layer 38 is obtained by patterning the organic active layer forming layer 34 as described above.

  In the present invention, the organic active layer 38 is a layer containing an organic compound. The layer configuration of the organic active layer 38 is not limited, but a thin film stack type in which a p-type semiconductor compound layer and an n-type semiconductor compound layer are stacked, and a layer in which a p-type semiconductor compound and an n-type semiconductor compound are mixed. Examples include a structure having a bulk heterojunction type, a layer in which a p-type semiconductor compound and an n-type semiconductor compound are mixed (i layer) as an intermediate layer of a thin film stack type. Among these, a bulk heterojunction active layer having a layer in which a p-type semiconductor compound and an n-type semiconductor compound are mixed is preferable.

  The film forming method for forming the organic active layer 38 is not particularly limited, and for example, a wet film forming method or a vacuum film forming method can be used. Especially, it is preferable to use the wet film-forming method which forms a layer by apply | coating the coating liquid containing a semiconductor compound. More specifically, the p-type semiconductor compound layer can be formed by applying a coating solution containing a p-type semiconductor compound, and the n-type semiconductor compound layer is applied with a coating solution containing an n-type semiconductor compound. The layer in which the p-type semiconductor compound and the n-type semiconductor compound are mixed can be formed by applying a coating solution containing the p-type semiconductor compound and the n-type semiconductor compound.

  Moreover, after apply | coating the coating liquid containing a p-type semiconductor compound precursor, you may convert a p-type semiconductor compound precursor into a p-type semiconductor compound, or after apply | coating the coating liquid containing an n-type semiconductor compound precursor. The n-type semiconductor compound precursor may be converted into an n-type semiconductor compound. Here, the semiconductor compound precursor refers to a compound that is converted into a semiconductor compound by applying an external stimulus such as heat or light.

  The specific wet film forming method is arbitrary, for example, spin coating method, reverse roll coating method, gravure coating method, kiss coating method, roll brush method, spray coating method, air knife coating method, wire barber coating method, pipe Examples include a doctor method, an impregnation / coating method, and a curtain coating method. As the p-type semiconductor compound and the n-type semiconductor compound, one type of compound may be used, or two or more types of compounds may be used in combination at an arbitrary ratio.

[5.1 p-type semiconductor compound]
The p-type semiconductor compound contained in the organic active layer 38 is not particularly limited, and examples thereof include a low molecular organic semiconductor compound and a high molecular organic semiconductor compound.

[1-4.1.1 Low molecular organic semiconductor compound]
The molecular weight of the low-molecular organic semiconductor compound is not particularly limited both at the upper limit and the lower limit, but is usually 5000 or less, preferably 2000 or less, and is usually 100 or more, preferably 200 or more. Further, the low molecular organic semiconductor compound preferably has crystallinity. The p-type semiconductor compound having crystallinity has a strong intermolecular interaction, and efficiently transports holes generated at the interface between the p-type semiconductor compound and the n-type semiconductor compound in the organic active layer 38 to the anode. This is because it is expected to be possible.

In the present specification, crystallinity refers to the property of a compound that takes a three-dimensional periodic array with uniform orientation due to intermolecular interaction or the like. Examples of the method for measuring crystallinity include X-ray diffraction (XRD) or field effect mobility measurement. In particular, in the field effect mobility measurement, a crystalline compound having a hole mobility of 1.0 × 10 ⁻⁵ cm ² / Vs or more is preferable, and a crystalline compound having 1.0 × 10 ⁻⁴ cm ² / Vs or more is preferable. Is more preferable. On the other hand, the hole mobility is usually 1.0 × 1
A crystalline compound of 0 ⁴ cm ² / Vs or less is preferred, a crystalline compound of 1.0 × 10 ³ cm ² / Vs or less is more preferred, and a crystallinity of 1.0 × 10 ² cm ² / Vs or less More preferred are compounds.

  The low-molecular organic semiconductor compound is not particularly limited as long as it satisfies the above-mentioned performance. Specifically, the condensed low-molecular organic hydrocarbon such as naphthacene, pentacene or pyrene; and four thiophene rings such as α-sexithiophene. Oligothiophenes containing above: those containing at least one of thiophene ring, benzene ring, fluorene ring, naphthalene ring, anthracene ring, thiazole ring, thiadiazole ring and benzothiazole ring, and a total of four or more linked; phthalocyanine compound And a metal complex thereof, or a porphyrin compound such as tetrabenzoporphyrin and a macrocycle compound thereof such as a metal complex thereof. Preferably, they are a phthalocyanine compound and its metal complex, or a porphyrin compound and its metal complex.

Examples of the porphyrin compound and its metal complex (Z ¹ in the following formula is CH), the phthalocyanine compound and its metal complex (Z ¹ in the following formula is N) used as the p-type semiconductor compound include the following structures: The compound of this is mentioned.

Here, M represents a metal or two hydrogen atoms. As the metal, in addition to a divalent metal such as Cu, Zn, Pb, Mg, Co or Ni, a trivalent or higher metal having an axial ligand. For example, TiO, VO, SnCl ₂ , AlCl, InCl, Si (OH) _2, or the like can be given.
R ^{11 to} R ¹⁴ are each independently a hydrogen atom or an alkyl group having 1 to 24 carbon atoms. The alkyl group having 1 to 24 carbon atoms is a saturated or unsaturated chain hydrocarbon group having 1 to 24 carbon atoms or a saturated or unsaturated cyclic hydrocarbon having 3 to 24 carbon atoms. . Among these, a saturated or unsaturated chain hydrocarbon group having 1 to 12 carbon atoms or a saturated or unsaturated cyclic hydrocarbon group having 3 to 12 carbon atoms is preferable.

  Among the phthalocyanine compounds and metal complexes thereof, 29H, 31H-phthalocyanine, copper phthalocyanine complex, zinc phthalocyanine complex, titanium phthalocyanine oxide complex, magnesium phthalocyanine complex, lead phthalocyanine complex or copper 4,4 ′, 4 ″, 4 '' '-Tetraaza-29H, 31H-phthalocyanine complex, more preferably 29H, 31H-phthalocyanine or copper phthalocyanine complex.

  Among the porphyrin compounds and metal complexes thereof, 5,10,15,20-tetraphenyl-21H, 23H-porphine, 5,10,15,20-tetraphenyl-21H, 23H-porphine cobalt (II), 5,10,15,20-tetraphenyl-21H, 23H-porphine copper (II), 5,10,15,20-tetraphenyl-21H, 23H-porphine zinc (II), 5,10,15,20- Tetraphenyl-21H, 23H-porphine nickel (II), 5,10,15,20-tetraphenyl-21H, 23H-porphine vanadium (IV) oxide, 5,10,15,20-tetra (4-pyridyl)- 21H, 23H-porphine, 29H, 31H-tetrabenzo [b, g, l, q] porphine, 2 H, 31H-tetrabenzo [b, g, l, q] porphine cobalt (II), 29H, 31H-tetrabenzo [b, g, l, q] porphine copper (II), 29H, 31H-tetrabenzo [b, g, l, q] porphine zinc (II), 29H, 31H-tetrabenzo [b, g, l, q] porphine nickel (II) or 29H, 31H-tetrabenzo [b, g, l, q] porphine vanadium (IV) oxide And preferably 5,10,15,20-tetraphenyl-21H, 23H-porphine or 29H, 31H-tetrabenzo [b, g, l, q] porphine.

  As described above, the layer containing a low molecular weight semiconductor compound is preferably formed by a wet film formation method. In particular, it is possible to form a layer containing a low molecular weight semiconductor compound by applying a coating liquid containing a low molecular weight semiconductor compound precursor and then converting the low molecular weight semiconductor compound precursor into a low molecular weight semiconductor compound. It is preferable in that the film is easy. Although there is no restriction | limiting in particular as a specific method, The method as described in Unexamined-Japanese-Patent No. 2007-324587 and Unexamined-Japanese-Patent No. 2011-119648 is mentioned.

[1-4.1.2 Polymer organic semiconductor compound]
The polymer organic semiconductor compound is not particularly limited, and is a conjugated polymer semiconductor such as polythiophene, polyfluorene, polyphenylene vinylene, polythienylene vinylene, polyacetylene, or polyaniline; a polymer such as oligothiophene substituted with an alkyl group or other substituent Semiconductor; and the like. Moreover, the semiconductor polymer which copolymerized 2 or more types of monomer units is also mentioned. The conjugated polymers, ^{e.g., Handbook of Conducting Polymers, 3 rd} Ed. (2 volumes), 2007, Materials Science and Engineering, 2001, 32, 1-40, Pure Appl. Chem. 2002, 74, 2031-3044, Handbook of THIOPHENE-BASED MATERIALS (2 volumes), 2009, etc. it can.

  Polymer monomer backbone and monomer substituents are selected to control solubility, crystallinity, film-formability, HOMO (highest occupied molecular orbital) energy level, LUMO (lowest unoccupied molecular orbital) energy level, etc. can do. In addition, it is preferable that the polymer organic semiconductor compound is soluble in an organic solvent in that a layer containing the polymer organic semiconductor compound can be formed by a wet film forming method. Specific examples of the polymer organic semiconductor compound include the following, but are not limited to the following.

  Among them, the p-type semiconductor compound is preferably a low molecular organic semiconductor compound such as condensed aromatic hydrocarbons such as naphthacene, pentacene, and pyrene, phthalocyanine compounds and metal complexes thereof, or porphyrin compounds such as tetrabenzoporphyrin (BP) and The metal complex and the polymer organic semiconductor compound is a conjugated polymer semiconductor such as polythiophene.

  The low-molecular organic semiconductor compound and / or the high-molecular organic semiconductor compound may have some self-organized structure in a film-formed state, or may be in an amorphous state.

  The HOMO energy level of the p-type semiconductor compound is not particularly limited, but can be selected depending on the type of the n-type semiconductor compound described later. In particular, when the fullerene compound is used as the n-type semiconductor compound, The HOMO energy level is usually −5.7 eV or more, more preferably −5.5 eV or more, and usually −4.6 eV or less, more preferably −4.8 eV or less. When the HOMO energy level of the p-type semiconductor compound is −5.7 eV or more, the characteristics as the p-type semiconductor are improved, and when the HOMO energy level of the p-type semiconductor is −4.6 eV or less, the p-type semiconductor is improved. The stability of the compound is improved, and the open circuit voltage (Voc) can be improved.

The LUMO energy level of the p-type semiconductor compound is not particularly limited, but can be selected according to the type of the n-type semiconductor compound described later. In particular, when a fullerene compound is used as an n-type semiconductor compound, the LUMO energy level of the p-type semiconductor compound is usually −3.7 eV or more, preferably −3.6 eV or more, while usually −2.5 eV or less, preferably Is −2.7 eV or less. When the LUMO energy level of the p-type semiconductor compound is −2.5 eV or less, the band gap can be adjusted to effectively absorb long-wavelength light energy, and the short-circuit current density (Jsc) can be improved. . When the LUMO energy level of the p-type semiconductor compound is −3.7 eV or more, electron transfer to the n-type semiconductor compound is likely to occur, and the short-circuit current density (Jsc) can be improved.

  As a calculation method of the HOMO energy level and the LUMO energy level, there are a theoretically calculated method and a method of actually measuring. Theoretically calculated methods include semi-empirical molecular orbital methods and non-empirical molecular orbital methods. Examples of the actual measurement method include ultraviolet-visible absorption spectrum measurement method and cyclic voltammogram measurement method. Among them, the cyclic voltammogram measurement method is preferable. In this specification, the HOMO energy level and the LUMO energy level refer to values with respect to a vacuum level calculated by a cyclic voltammogram measurement method.

[1-4.2 n-type semiconductor compound]
The n-type semiconductor compound is not particularly limited. Specifically, the fullerene compound; a quinolinol derivative metal complex represented by 8-hydroxyquinoline aluminum; a condensed ring such as naphthalenetetracarboxylic acid diimide or perylenetetracarboxylic acid diimide Tetracarboxylic acid diimides; perylene diimide derivatives, terpyridine metal complexes, tropolone metal complexes, flavonol metal complexes, perinone derivatives, benzimidazole derivatives, benzoxazole derivatives, thiazole derivatives, benzthiazole derivatives, benzothiadiazole derivatives, oxadiazole derivatives, thiadiazoles Derivatives, triazole derivatives, aldazine derivatives, bisstyryl derivatives, pyrazine derivatives, phenanthroline derivatives, quinoxaline derivatives, benzoquinoline derivatives Bipyridine derivatives, borane derivatives, anthracene, pyrene, total fluoride condensed polycyclic aromatic hydrocarbons such as naphthacene or pentacene; single-walled carbon nanotubes, and the like.

  Among them, fullerene compounds, borane derivatives, thiazole derivatives, benzothiazole derivatives, benzothiadiazole derivatives, N-alkyl-substituted naphthalenetetracarboxylic acid diimides or N-alkyl-substituted perylene diimide derivatives are preferable, fullerene compounds, N-alkyl More preferred are substituted perylene diimide derivatives or N-alkyl substituted naphthalene tetracarboxylic acid diimides.

  Examples of the n-type semiconductor compound include an n-type polymer semiconductor compound. Specifically, although there is no particular limitation, condensed ring tetracarboxylic acid diimides such as naphthalene tetracarboxylic acid diimide or perylene tetracarboxylic acid diimide, perylene diimide derivatives, benzimidazole derivatives, benzoxazole derivatives, thiazole derivatives, benzothiazoles Derivatives, benzothiadiazole derivatives, oxadiazole derivatives, thiadiazole derivatives, triazole derivatives, pyrazine derivatives, phenanthroline derivatives, quinoxaline derivatives, bipyridine derivatives, and borane derivatives include n-type polymer semiconductor compounds. . Among them, polymers having at least one of borane derivatives, thiazole derivatives, benzthiazole derivatives, benzothiadiazole derivatives, N-alkyl-substituted naphthalenetetracarboxylic acid diimides and N-alkyl-substituted perylene diimide derivatives as constituent units Preferably, an n-type polymer semiconductor compound comprising at least one of the n-type polymer semiconductor compound comprising N-alkyl-substituted perylene diimide derivative and N-alkyl-substituted naphthalenetetracarboxylic acid diimide as a constituent unit Is more preferable.

The LUMO energy level of the n-type semiconductor compound is not particularly limited, but is usually −3.85 eV or more, preferably −3.80 eV or more. In order to efficiently move electrons from a p-type semiconductor to an n-type semiconductor, the relative relationship of LUMO energy levels between the p-type semiconductor compound and the n-type semiconductor compound is important. Specifically, the LUMO energy level of the p-type semiconductor compound is higher than the LUMO energy level of the n-type semiconductor compound by a predetermined energy, in other words, the electron affinity of the n-type semiconductor compound is p-type semiconductor compound. It is preferable that a predetermined energy is larger than the electron affinity. Since the open-circuit voltage (Voc) depends on the difference between the HOMO energy level of the p-type semiconductor compound and the LUMO energy level of the n-type semiconductor compound, increasing the LUMO energy level of the n-type semiconductor compound increases the open-circuit voltage (Voc). ) Tends to be high.

On the other hand, the LUMO energy level of the n-type semiconductor compound is usually −1.0 eV or less, preferably −2.0 eV or less, more preferably −3.0 eV or less, and further preferably −3.3 eV or less. By lowering the LUMO energy level of the n-type semiconductor compound, electron transfer tends to occur and the short circuit current (Jsc) tends to increase.
The HOMO energy level of the n-type semiconductor compound is not particularly limited, but is usually −5.0 eV or less, preferably −5.5 eV or less. On the other hand, it is usually −7.0 eV or more, preferably −6.6 eV or more. It is preferable that the HOMO energy level of the n-type semiconductor compound is −7.0 eV or more because light absorption by the n-type semiconductor compound can also be used for power generation. It is preferable that the HOMO energy level of the n-type semiconductor compound is −5.0 eV or less from the viewpoint of preventing reverse movement of holes.

The electron mobility of the n-type semiconductor compound is not particularly limited, but is usually 1.0 × 10 ⁻⁶ cm ² / Vs or more, preferably 1.0 × 10 ⁻⁵ cm ² / Vs or more. 0 × 10 ⁻⁵ cm ² / Vs or more is more preferable, and 1.0 × 10 ⁻⁴ cm ² / Vs or more is more preferable. On the other hand, it is usually 1.0 × 10 ⁴ cm ² / Vs or less, preferably 1.0 × 10 ³ cm ² / Vs or less, and more preferably 1.0 × 10 ² cm ² / Vs or less. When the electron mobility of the n-type semiconductor compound is 1.0 × 10 ⁻⁶ cm ² / Vs or more, effects such as improvement of the electron diffusion rate, improvement of short circuit current, improvement of conversion efficiency of the photoelectric conversion element tend to increase. Because there is a certain tendency, it is preferable.

As a method for measuring electron mobility, field effect transistor (FET) measurement can be mentioned, and specifically, it can be carried out by a method described in known literature (Japanese Patent Application Laid-Open No. 2010-045186).
The solubility of the n-type semiconductor compound in toluene at 25 ° C. is usually 0.5% by weight or more, preferably 0.6% by weight or more, and more preferably 0.7% by weight or more. On the other hand, it is usually preferably 90% by weight or less, more preferably 80% by weight or less, and further preferably 70% by weight or less. When the solubility of the n-type semiconductor compound is 0.5% by weight or more, the dispersion stability of the n-type semiconductor material is improved in a solution containing the n-type semiconductor compound, and aggregation, sedimentation, separation, and the like are less likely to occur. Therefore, it is preferable in that film formation by a wet film formation method is easy.
Hereinafter, these preferable n-type semiconductor compounds will be further described.

[1-4.2.1 Fullerene Compound]
As a fullerene compound, what has the partial structure represented by general formula (n1), (n2), (n3) and (n4) is preferable.

In formulas (n1) to (n4), FLN represents fullerene which is a carbon cluster having a closed shell structure. The carbon number of fullerene is not particularly limited as long as it is usually an even number of 60 to 130. Examples of fullerenes include C ₆₀ , C ₇₀ , C ₇₆ , C ₇₈ , C ₈₂ , C ₈₄ , C ₉₀ , C ₉₄ , C ₉₆ and higher carbon clusters having more carbon than these. . Among these, _C60 or _C70 is preferable. As fullerenes, carbon-carbon bonds on some fullerene rings may be broken. Some carbon atoms may be replaced with other atoms. Furthermore, a metal atom, a non-metal atom, or an atomic group composed of these may be included in the fullerene cage.

a, b, c and d are integers, and the sum of a, b, c and d is usually 1 or more, and usually 5 or less, preferably 3 or less. The partial structures represented by (n1), (n2), (n3) and (n4) are added to the same 5-membered ring or 6-membered ring in the fullerene skeleton. In the general formula (n1), —R ²¹ and — (CH ₂ ) _L are added to two adjacent carbon atoms on the same 5-membered ring or 6-membered ring in the fullerene skeleton. In the general formula (n2), -C (R ²⁵ ) (R ²⁶ ) -N (R ²⁷ ) -C with respect to two adjacent carbon atoms on the same 5-membered ring or 6-membered ring in the fullerene skeleton. (R ²⁸ ) (R ²⁹ ) — are added to form a 5-membered ring. In the general formula (n3), —C (R ³⁰ ) (R ³¹ ) —C—C—C (R) with respect to two adjacent carbon atoms on the same 5-membered ring or 6-membered ring in the fullerene skeleton. ³² ) (R ³³ ) — are added to form a 6-membered ring. In the general formula (n4), —C (R ³⁴ ) (R ³⁵ ) — is added to two adjacent carbon atoms on the same 5-membered ring or 6-membered ring in the fullerene skeleton to form a 3-membered ring. Forming. L is an integer of 1 to 8. L is preferably an integer of 1 to 4, more preferably an integer of 1 to 2.

In the general formula (n1), R ²¹ is an alkyl group having 1 to 14 carbon atoms which may have a substituent, an alkoxy group having 1 to 14 carbon atoms which may have a substituent, or a substituent. An aromatic group which may have a group.
As the alkyl group, those having 1 to 10 carbon atoms are preferred, methyl group, ethyl group,
An n-propyl group, an isopropyl group, an n-butyl group or an isobutyl group is more preferable, and a methyl group or an ethyl group is more preferable.

As an alkoxy group, a C1-C10 thing is preferable, a C1-C6 thing is more preferable, and a methoxy group or an ethoxy group is especially preferable.
The aromatic group is preferably an aromatic hydrocarbon group having 6 to 20 carbon atoms or an aromatic heterocyclic group having 2 to 20 carbon atoms, more preferably a phenyl group, a thienyl group, a furyl group, or a pyridyl group. A group or a thienyl group is more preferred.

  As the substituent that the alkyl group, alkoxy group and aromatic group may have, a halogen atom or a silyl group is preferable. As the halogen atom, a fluorine atom is preferable. The silyl group is preferably a diarylalkylsilyl group, a dialkylarylsilyl group, a triarylsilyl group or a trialkylsilyl group, more preferably a dialkylarylsilyl group, and even more preferably a dimethylarylsilyl group.

In the general formula (n1), R ^{22 to} R ²⁴ each independently represent a substituent, which has a hydrogen atom, an alkyl group having 1 to 14 carbon atoms which may have a substituent, or a substituent. An aromatic group that may be used.
As an alkyl group, a C1-C10 thing is preferable and a methyl group, an ethyl group, n-propyl group, isopropyl group, n-butyl group, isobutyl group, t-butyl group, or n-hexyl group is preferable. The substituent that the alkyl group may have is preferably a halogen atom. As the halogen atom, a fluorine atom is preferable. The alkyl group substituted with a fluorine atom is preferably a perfluorooctyl group, a perfluorohexyl group or a perfluorobutyl group.

  The aromatic group is preferably an aromatic hydrocarbon group having 6 to 20 carbon atoms or an aromatic heterocyclic group having 2 to 20 carbon atoms, more preferably a phenyl group, a thienyl group, a furyl group, or a pyridyl group. A group or a thienyl group is more preferred. Examples of the substituent that the aromatic group may have include a fluorine atom, an alkyl group having 1 to 14 carbon atoms, a fluorinated alkyl group having 1 to 14 carbon atoms, an alkoxy group having 1 to 14 carbon atoms, or An aromatic group having 2 to 10 carbon atoms is preferred, a fluorine atom or an alkoxy group having 1 to 14 carbon atoms is more preferred, and a methoxy group, n-butoxy group or 2-ethylhexyloxy group is further preferred. When the aromatic group has a substituent, the number is not limited, but is preferably 1 or more and 3 or less, and more preferably 1. When the aromatic group has a plurality of substituents, the types of the substituents may be different, but are preferably the same.

In the general formula (n2), R ^{25 to} R ²⁹ are each independently a hydrogen atom, an alkyl group having 1 to 14 carbon atoms which may have a substituent, or an aromatic group optionally having a substituent. It is a group.
The alkyl group is preferably a methyl group, ethyl group, n-propyl group, isopropyl group, n-butyl group, isobutyl group, n-hexyl group or octyl group, and more preferably a methyl group. The substituent that the alkyl group may have is preferably a halogen atom. As the halogen atom, a fluorine atom is preferable. The alkyl group substituted with a fluorine atom is preferably a perfluorooctyl group, a perfluorohexyl group or a perfluorobutyl group.

As the aromatic group, an aromatic hydrocarbon group having 6 to 20 carbon atoms or an aromatic heterocyclic group having 2 to 20 carbon atoms is preferable, a phenyl group or a pyridyl group is more preferable, and a phenyl group is further preferable. The substituent that the aromatic group may have is not particularly limited, but is preferably a fluorine atom, an alkyl group having 1 to 14 carbon atoms, or an alkoxy group having 1 to 14 carbon atoms. The alkyl group may be substituted with a fluorine atom. More preferably, it is an alkoxy group having 1 to 14 carbon atoms, and more preferably a methoxy group. When it has a substituent, there is no limitation in the number, However, Preferably it is 1-3, More preferably, it is 1. The types of substituents may be different, but are preferably the same.

In the general formula (n3), Ar ¹ is an optionally substituted aromatic hydrocarbon group having 6 to 20 carbon atoms or an aromatic heterocyclic group having 2 to 20 carbon atoms, preferably A phenyl group, a naphthyl group, a biphenyl group, a thienyl group, a furyl group, a pyridyl group, a pyrimidyl group, a quinolyl group or a quinoxalyl group, more preferably a phenyl group, a thienyl group or a furyl group.

  Although there is no limitation in particular as a substituent which you may have, a fluorine atom, a chlorine atom, a hydroxyl group, a cyano group, a silyl group, a boryl group, the amino group which may be substituted by the alkyl group, C1-C14 or less An alkyl group having 1 to 14 carbon atoms, an alkylcarbonyl group having 1 to 14 carbon atoms, an alkylthio group having 1 to 14 carbon atoms, an alkenyl group having 2 to 14 carbon atoms, and 2 to 14 carbon atoms. The following alkynyl groups, ester groups having 2 to 14 carbon atoms, arylcarbonyl groups having 3 to 20 carbon atoms, arylthio groups having 2 to 20 carbon atoms, aryloxy groups having 2 to 20 carbon atoms, 6 carbon atoms An aromatic hydrocarbon group having 20 to 20 carbon atoms or a heterocyclic group having 2 to 20 carbon atoms is preferable, a fluorine atom, an alkyl group having 1 to 14 carbon atoms, and 1 carbon atom. Above 14 an alkoxy group, having 2 to 14 ester groups carbons, an alkyl group or having 3 to 20 arylcarbonyl group carbons of 2 to 14 carbon atoms and more preferable. The alkyl group having 1 to 14 carbon atoms may be substituted with one or more fluorine atoms. When it has a substituent, although there is no limitation in the number, 1-4 are preferable and 1-3 are more preferable. When there are a plurality of substituents, the types may be different, but are preferably the same.

  The alkyl group having 1 to 14 carbon atoms is preferably a methyl group, an ethyl group or a propyl group. The alkoxy group having 1 to 14 carbon atoms is preferably a methoxy group, an ethoxy group, or a propoxyl group. The alkylcarbonyl group having 1 to 14 carbon atoms is preferably an acetyl group. The ester group having 2 to 14 carbon atoms is preferably a methyl ester group or an n-butyl ester group. The arylcarbonyl group having 3 to 20 carbon atoms is preferably a benzoyl group.

In General Formula (n3), R ^{30 to} R ³³ each independently have a hydrogen atom, an alkyl group that may have a substituent, an amino group that may have a substituent, or a substituent. It is an optionally substituted alkoxy group or an optionally substituted alkylthio group. R ³⁰ or R ³¹ may be bonded to R ³² or R ³³ to form a ring. As an example of the case where R ³⁰ or R ³¹ is bonded to R ³² or R ³³ to form a ring, a structure of the general formula (n5) which is a bicyclo structure in which an aromatic group is condensed can be given.

F In the general formula (n5) is the same integer and c, Z ² represents an oxygen atom, a sulfur atom, an amino group, an alkylene group or an arylene group.
As an alkylene group, a C1-C2 thing is preferable, and a methylene group or an ethylene unit is mentioned. As the arylene group, those having 5 to 12 carbon atoms are preferable, and examples thereof include a phenylene group. The amino group may be substituted with an alkyl group having 1 to 6 carbon atoms such as a methyl group or an ethyl group. The alkylene group is an alkoxy group having 1 to 6 carbon atoms such as a methoxy group, an aliphatic hydrocarbon group having 1 to 5 carbon atoms, an aromatic hydrocarbon group having 6 to 20 carbon atoms, or 2 to 20 carbon atoms. The aromatic heterocyclic group may be substituted. The arylene group is an alkoxy group having 1 to 6 carbon atoms such as a methoxy group, an aliphatic hydrocarbon group having 1 to 5 carbon atoms, an aromatic hydrocarbon group having 6 to 20 carbon atoms, or 2 to 20 carbon atoms. The aromatic heterocyclic group may be substituted.
The structure represented by the formula (n5) is particularly preferably a structure represented by the following formula (n6) or the formula (n7).

In General Formula (n4), R ^{34 to} R ³⁵ each independently have a hydrogen atom, an alkoxycarbonyl group, an alkyl group having 1 to 14 carbon atoms that may have a substituent, or a substituent. An aromatic group that may be used. When it has a substituent, the number is not limited, but it is preferably 1 or more and 3 or less, more preferably 1. The types of substituents may be different or the same, preferably the same.

The alkoxy group constituting the alkoxycarbonyl group is preferably an alkoxy group having 1 to 12 carbon atoms or a fluorinated alkoxy group having 1 to 12 carbon atoms, more preferably an alkoxy group having 1 to 12 carbon atoms, and a methoxy group. Ethoxy group, n-propoxy group, isopropoxy group, n-butoxy group, isobutoxy group, n-hexoxy group, octoxy group, 2-propylpentoxy group, 2-ethylhexoxy group, cyclohexylmethoxy group or benzyloxy group A methoxy group, an ethoxy group, an isopropoxy group, an n-butoxy group, an isobutoxy group or an n-hexoxy group is particularly preferable.

  As the alkyl group, a linear alkyl group having 1 to 8 carbon atoms is preferable, and an n-propyl group is more preferable. The substituent that the alkyl group may have is not particularly limited, but is preferably an alkoxycarbonyl group. The alkoxy group constituting the alkoxycarbonyl group is preferably an alkoxy group having 1 to 14 carbon atoms or a fluorinated alkoxy group, more preferably an alkoxy group having 1 to 14 carbon atoms, a methoxy group, an ethoxy group, or n-propoxy. Group, isopropoxy group, n-butoxy group, isobutoxy group, n-hexoxy group, octoxy group, 2-propylpentoxy group, 2-ethylhexoxy group, cyclohexylmethoxy group or benzyloxy group, more preferably methoxy group or n- A butoxy group is particularly preferred.

  As the aromatic group, an aromatic hydrocarbon group having 6 to 20 carbon atoms or an aromatic heterocyclic group having 2 to 20 carbon atoms is preferable, and a phenyl group, a biphenyl group, a thienyl group, a furyl group, or a pyridyl group is preferable. More preferred are a phenyl group and a thienyl group. The substituent that the aromatic group may have is preferably an alkyl group having 1 to 14 carbon atoms, a fluorinated alkyl group having 1 to 14 carbon atoms, or an alkoxy group having 1 to 14 carbon atoms. An alkoxy group having a number of 1 or more and 14 or less is more preferable, and a methoxy group or 2-ethylhexyloxy group is particularly preferable.

Preferred examples of the structure represented by formula (n4) include those in which R ³⁴ and R ³⁵ are both alkoxycarbonyl groups, those in which R ³⁴ and R ³⁵ are both aromatic groups, and R ³⁴ is an aromatic group. And R ³⁵ is a 3- (alkoxycarbonyl) propyl group.
In order to form a layer containing a fullerene compound using a wet film formation method, the fullerene compound itself can be applied in a liquid state, or the fullerene compound can be applied as a solution with high solubility in some solvent. It is preferable. The solubility of the fullerene compound used in toluene at 25 ° C. is usually 0.1% by weight or more, preferably 0.4% by weight or more, more preferably 0.7% by weight or more. When the solubility of the fullerene compound is 0.1% by weight or more, the dispersion stability of the fullerene compound in the solution containing the fullerene compound is increased, and aggregation, sedimentation, separation, and the like are less likely to occur. It is preferable in that the film formation by is easy.

  In the case of forming a layer containing a fullerene compound using a wet film forming method, the solvent of the solution containing the fullerene compound is not particularly limited as long as it is a nonpolar organic solvent, but a non-halogen solvent is preferable. Although it is possible to use a halogen-based solvent such as dichlorobenzene, an alternative is demanded from the viewpoint of environmental load. Examples of non-halogen solvents include non-halogen aromatic hydrocarbons. Of these, toluene, xylene, cyclohexylbenzene, and the like are preferable.

(Method for producing fullerene compound)
Although there is no restriction | limiting in particular as a manufacturing method of a fullerene compound, For example, the synthesis | combination of fullerene which has a partial structure (n1) is international publication 2008/059771 or J.H. Am. Chem. Soc. , 2008, 130 (46), 15429-15436.

The synthesis of fullerene having a partial structure (n2) is described in J. Org. Am. Chem. Soc. 1993, 115, 9798-9799, Chem. Mater. 2007, 19, 5363-5372 or Chem. Mater. It can be carried out according to the description of known documents such as 2007, 19, 5194-5199.
Synthesis of fullerene having a partial structure (n3) is described in Angew. Chem. Int. Ed. Engl. 1993, 32, 78-80, Tetrahedron Lett. It can be carried out according to the description of known documents such as 1997, 38, 285-288, WO 2008/018931 or WO 2009/086212.

  The synthesis of fullerene having a partial structure (n4) is described in J. Org. Chem. Soc. Perkin Trans. 1, 1997, 1595, Thin Solid Films 489 (2005) 251-256, Adv. Funct. Mater. 2005, 15, 1979-1987 or J. Org. Org. Chem. It can be carried out according to the description of known documents such as 1995, 60, 532-538.

[1-4.2.2 N-alkyl-substituted perylene diimide derivatives]
N-alkyl-substituted perylene diimide derivatives are not particularly limited, and specifically, International Publication No. 2008/063609, International Publication No. 2009/115553, International Publication No. 2009/098250, International Publication No. Examples thereof include compounds described in 2009/000756 and International Publication No. 2009/091670. These compounds are preferable because they have high electron mobility and absorb light in the visible region, and thus can contribute to both charge transport and power generation.

[1-4.2.3 Naphthalenetetracarboxylic acid diimide]
The naphthalenetetracarboxylic acid diimide is not particularly limited, and specific examples thereof include compounds described in International Publication No. 2008/063609, International Publication No. 2007/146250 and International Publication No. 2009/000756. It is done. These compounds are preferable because they have high electron mobility, high solubility, and excellent coating properties.

[1-4.2.4 n-type polymer semiconductor compound]
The n-type polymer semiconductor compound is not particularly limited, but condensed ring tetracarboxylic acid diimides such as naphthalene tetracarboxylic acid diimide or perylene tetracarboxylic acid diimide, perylene diimide derivatives, benzimidazole derivatives, benzoxazole derivatives, thiazoles N-type polymer semiconductor comprising at least one of a derivative, a benzothiazole derivative, a benzothiadiazole derivative, an oxadiazole derivative, a thiadiazole derivative, a triazole derivative, a pyrazine derivative, a phenanthroline derivative, a quinoxaline derivative, a bipyridine derivative and a borane derivative Compounds and the like.

  Among them, at least one of a borane derivative, a thiazole derivative, a benzothiazole derivative, a benzothiadiazole derivative, an N-alkyl-substituted naphthalenetetracarboxylic acid diimide derivative, and an N-alkyl-substituted perylenetetracarboxylic acid diimide derivative is a constituent unit. Preferred is an n-type polymer semiconductor compound having at least one of N-alkyl-substituted perylenetetracarboxylic acid diimide derivative and N-alkyl-substituted naphthalenetetracarboxylic acid diimide derivative as a constituent unit. .

Specific examples of the n-type polymer semiconductor compound include compounds described in International Publication No. 2009/098253, International Publication No. 2009/098250, International Publication No. 2010/012710, and International Publication No. 2009/098250. Can be mentioned. These compounds are
This is preferable from the viewpoint of absorbing light in the visible region and contributing to power generation, and having high viscosity and excellent coating properties.

<2. Solar cell>
Although the organic thin film solar cell according to the present invention can be manufactured by the method described above, the organic thin film solar cell may include constituent members other than those described above.
FIG. 2 is a cross-sectional view schematically showing the configuration of the organic thin-film solar cell 14 as one embodiment of the present invention. As shown in FIG. 2, the thin film solar cell 14 of this embodiment includes a weather-resistant protective film 1, an ultraviolet cut film 2, a gas barrier film 3, a getter material film 4, a sealing material 5, and a solar cell element. 6, a sealing material 7, a getter material film 8, a gas barrier film 9, and a back sheet 10 are provided in this order. And light is irradiated from the side (downward in the figure) where the weather-resistant protective film 1 is formed, and the solar cell element 6 generates power. In addition, when using a highly waterproof sheet such as a sheet obtained by bonding a fluororesin film on both surfaces of an aluminum foil as the back sheet 10 described later, the getter material film 8 and / or the gas barrier film 9 may not be used depending on the application. Good. The materials, shapes, performances, and lamination methods of these encapsulant 5, backsheet 10 and various films are all as described in International Publication No. 2011/016430 or Japanese Patent Application Laid-Open No. 2012-191194. .

<3. Application>
There is no restriction | limiting in the use of the organic thin film solar cell 14 mentioned above, It is arbitrary. For example, as schematically shown in FIG. 3, a thin film solar cell 14 may be provided on some base material 12 and used at a place of use. As a specific example, when a building material plate is used as the base material 12, a thin-film solar cell 14 is produced on the surface of the plate material, and this solar cell panel is used on the outer wall of a building. That's fine.

  The substrate 12 is a support member that supports the solar cell element 6. Examples of the material for forming the substrate 12 include inorganic materials such as glass, sapphire, and titania; polyethylene terephthalate, polyethylene naphthalate, polyethersulfone, polyimide, nylon, polystyrene, polyvinyl alcohol, ethylene vinyl alcohol copolymer, fluorine. Organic materials such as resin film, vinyl chloride, polyethylene, cellulose, polyvinylidene chloride, aramid, polyphenylene sulfide, polyurethane, polycarbonate, polyarylate, polynorbornene; paper materials such as paper or synthetic paper; metals such as stainless steel, titanium or aluminum For example, a composite material such as a material whose surface is coated or laminated in order to impart insulating properties can be used. In addition, 1 type may be used for the material of a base material, and 2 or more types may be used together by arbitrary combinations and a ratio. Moreover, carbon fiber may be included in these organic materials or paper materials to reinforce the mechanical strength.

  When the example of the field | area which applies the thin film solar cell of this invention is given, as it exists in international publication 2011/016430 or Unexamined-Japanese-Patent No. 2012-191194, for example, it is a solar cell for building materials, a solar cell for motor vehicles, and interior use. It is suitable for use in solar cells, railroad solar cells, marine solar cells, airplane solar cells, spacecraft solar cells, home appliance solar cells, mobile phone solar cells, toy solar cells, and the like.

Examples of the present invention will be described below. In addition, this invention is not limited to a following example, A design can be changed suitably in the range which does not deviate from the meaning of this invention.
(Synthesis Example 1: Synthesis of Copolymer A)

  As a monomer, 1,3-dibromo-5-octyl-4H-thieno [3,4-c obtained by referring to a method described in known literature (J. Am. Chem. Soc. 2011, 133, 10062) ] Pyrrole-4,6- (5H) -dione (Compound E1, 86 mg, 0.204 mmol), obtained by referring to the method described in known literature (J. Am. Chem. Soc. 2011, 133, 10062). 4,4-bis (2-ethylhexyl) -2,6-bis (trimethyltin) -dithieno [3,2-b: 2 ′, 3′-d] silole (compound E2, 80 mg, 0.108 mmol), And 4,4-di-n-octyl-2,6-bis (tri-methyl ether) obtained by referring to the methods described in known literature (Chem. Commun., 2011, 47, 4920-4922). Tiltin) -dithieno [3,2-b: 2 ′, 3′-d] silole (compound E3, 80 mg, 0.108 mmol) was used to make known literature (J. Am. Chem. Soc. 2011, 133, 10062). The copolymer A was synthesized with reference to the method described in 1).

In addition, when the weight average molecular weight Mw and molecular weight distribution PDI of the obtained copolymer A were measured on condition of the following, they were 3.69 * 10 < ⁵ > and 9.4, respectively.
(Measurement method of weight average molecular weight and number average molecular weight)
The weight average molecular weight (Mw) and number average molecular weight (Mn) in terms of polystyrene were determined by gel permeation chromatography (GPC). Molecular weight distribution (PDI) represents Mw / Mn.

Gel permeation chromatography (GPC) measurement was performed under the following conditions.
Column: Polymer Laboratories GPC column (PLgel MIXED-B 10 μm, inner diameter 7.5 mm, length 30 cm) connected in series Pump: LC-10AT (manufactured by Shimadzu Corporation)
Oven: CTO-10A (manufactured by Shimadzu Corporation)
Detector: differential refractive index detector (manufactured by Shimadzu Corporation, RID-10A) and UV-vis detector (manufactured by Shimadzu Corporation, SPD-10A)
Sample: 1 μL of 1 mg sample dissolved in chloroform (200 mg)
Mobile phase: Chloroform Flow rate: 1.0 mL / min
Analysis: LC-Solution (manufactured by Shimadzu Corporation)

(Preparation of active layer ink 1)
The copolymer A obtained in Synthesis Example 1 as a p-type semiconductor compound and the fullerene mixture (NS-E124 manufactured by Frontier Carbon Co., Ltd.) as an n-type semiconductor compound are mixed so that the weight ratio is 1: 2.5. Was dissolved in a mixed solvent of orthoxylene and tetralin (weight ratio 9: 1) in a nitrogen atmosphere so as to have a concentration of 4.55% by weight. This solution was stirred and mixed on a hot stirrer at a temperature of 80 ° C. for 1 hour. The solution after stirring and mixing was filtered through a polytetrafluoroethylene (PTFE) filter having a pore size of 5 μm to obtain ink 1 as an active layer coating solution.

Example 1
(Preparation of photoelectric conversion element 1)
PEN-lower electrode laminate in which indium tin oxide (ITO) and silver (Ag) are laminated as a lower electrode on a PEN substrate with a thickness of 125 μm (ITO-Ag-ITO) (sheet resistance with a transmittance of 80% or more) 15Ω / □ or less) was patterned using a Keyence laser marker (MDV9920A). The patterned PEN-lower electrode laminate was lightly wiped with an alpha wiper soaked in water and dried with nitrogen blow. The height of pattern edge unevenness (burrs) on the substrate was 400 nm on average. The substrate size was further cut as necessary.

Next, in the PEN-lower electrode laminate after cleaning, a solution containing zinc oxide (ZnO) nanoparticles (BYK, BYK3841) was diluted eight times by weight with IPA in an air atmosphere, and 100 nm by spin coating. A ZnO layer (first intermediate layer forming layer) having a thickness of 5 mm was formed. After film formation, the substrate was heated at 120 ° C. for 2 minutes and dried.
The substrate on which the first intermediate layer forming layer was formed was subjected to nitrogen blowing treatment, and the organic active layer forming layer having a thickness of 400 nm was formed by spin coating the ink 1 produced as described above in the atmosphere, This was heat-treated at 120 ° C. for 2 minutes in a dryer under a nitrogen atmosphere.

  Furthermore, a second intermediate layer forming layer having a thickness of 200 nm was formed on the organic active layer forming layer by spin coating a PEDOT: PSS solution in the air. In addition, it was 10E-4S / cm when the PEDOT: PSS layer of the same film thickness was separately formed, and the electrical conductivity was measured. After forming the second intermediate layer forming layer, if necessary, wipe around the element and the portion corresponding to the contact electrode with an alpha wiper containing EtOH, and then successively resistance-heat a silver film with a thickness of 100 nm as the upper electrode. A film was formed by a mold vacuum deposition method to produce a 7 mm square photoelectric conversion element. Eight elements were manufactured under the same conditions.

  (Example 2) A device was fabricated in the same manner as in Example 1 except that the film thickness of the second intermediate layer forming layer was changed to 300 nm. The results are shown in Table 1.

  Example 3 A device was fabricated in the same manner as in Example 1 except that the thickness of the organic active layer forming layer was changed to 300 nm. The results are shown in Table 1.

  Example 4 A device was fabricated in the same manner as in Example 1 except that the thickness of the first intermediate layer formation layer was changed to 200 nm and the thickness of the second intermediate layer formation layer was changed to 500 nm. Produced. The results are shown in Table 1.

(Comparative Example 1)
A device was produced in the same manner as in Example 1 except that the thickness of the organic active layer forming layer was changed to 100 nm. The results are shown in Table 1.

(Comparative Example 2)
A device was fabricated in the same manner as in Example 1 except that the thickness of the second intermediate layer forming layer was changed to 50 nm. The results are shown in Table 1.

(Evaluation of photoelectric conversion element)
In Examples 1 to 4 and Comparative Examples 1 and 2, the produced photoelectric conversion elements were evaluated for short-circuiting of the elements. The evaluation method was described as “defective” when 5 or more of 8 elements were short-circuited, and “good” when no short-circuited element was generated.

From the result of Table 1, it was shown that the photoelectric conversion element produced in Examples 1-4 functioned as a photoelectric conversion element, without short-circuiting all. On the other hand, many of the photoelectric conversion elements produced in Comparative Examples 1 and 2 were short-circuited, and did not function as photoelectric conversion elements.
As described above, in the patterning process of the lower electrode formation layer, the first intermediate layer formation layer, the organic active layer formation layer, and the second intermediate layer formation layer are formed with a specific thickness as in the present invention. Even if burrs occur, an organic thin-film solar cell that does not cause a short circuit without requiring a special additional process can be provided.

DESCRIPTION OF SYMBOLS 1 Weatherproof protective film 2 Ultraviolet cut film 3,9 Gas barrier film 4,8 Getter material film 5,7 Sealing material 6 Organic thin film photovoltaic cell 10 Back sheet 12 Base material 14 Solar cell 31 Substrate 32 Lower electrode 33 1st Intermediate layer forming layer 34 Organic active layer forming layer 35 Second intermediate layer forming layer 36 Upper electrode forming layer 37 First intermediate layer 38 Organic active layer 39 Second intermediate layer 40 Upper electrodes 41, 42, 43 Grooves

Claims (3)

Patterning the lower electrode formation layer laminated on the substrate;
Forming a first intermediate layer forming layer on the patterned lower electrode forming layer;
Forming an organic active layer forming layer on the first intermediate layer forming layer;
Forming a second intermediate layer forming layer on the organic active layer forming layer, comprising:
The manufacturing method of the organic thin film photovoltaic cell whose sum total of the film thickness of a said 1st intermediate | middle layer formation layer, the said organic active layer formation layer, and a said 2nd intermediate | middle layer formation layer is 600 nm or more and 2500 nm or less.   The ratio of the film thickness of the organic active layer forming layer to the total film thickness of the first intermediate layer forming layer and the second intermediate layer forming layer is 0.4 or more and 4.0 or less. The manufacturing method of the organic thin film photovoltaic cell of description.   The method for producing an organic thin-film solar cell according to claim 1, 2 or 3, wherein the patterning is performed by a laser scribing method.